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magnetic separation water treatment

magnetic separation - an overview | sciencedirect topics

magnetic separation - an overview | sciencedirect topics

Magnetic separations take advantages of natural magnetic properties between minerals in feed. The separation is between economic ore constituents, noneconomic contaminants and gangue. Magnetite and ilmenite can be separated from its nonmagnetic RFM of host rock as valuable product or as contaminants. The technique is widely used in beneficiation of beach sand. All minerals will have one of the three magnetic properties. It is ferromagnetic (magnetite, pyrrhotite etc.), paramagnetic (monazite, ilmenite, rutile, chromite, wolframite, hematite, etc.) or diamagnetic (plagioclase, calcite, zircon and apatite etc.). Commercial magnetic separation units follow continuous separation process on a moving stream of dry or wet particles passing through low or high magnetic field. The various magnetic separators are drum, cross-belt, roll, high-gradient magnetic separation (HGMS), high-intensity magnetic separation (HIMS) and low-intensity magnetic separation (LIMS) types.

Drum separator consists of a nonmagnetic drum fitted with three to six permanent magnets. It is composed of ceramic or rare earth magnetic alloys in the inner periphery (Fig. 12.34). The drum rotates at uniform motion over a moving stream of preferably wet feed. The ferromagnetic and paramagnetic minerals are picked up by the rotating magnets and pinned to the outer surface of the drum. As the drum moves up the concentrate is compressed, dewatered and discharged leaving the gangue in the tailing compartment. The drum rotation can be clockwise or counterclockwise and the collection of concentrate is designed accordingly. Drum separator produces extremely clean magnetic concentrate.

Cross-belt separator consists of a magnet fixed over the moving belt carrying magnetic feed (Fig. 12.35). The magnet lifts the magnetic minerals and puts across the field leaving the gangue to tailing. The system is widely used in mineral beach sand industry for separation of ilmenite and rutile. However, it is replaced by rare earth role magnetic and rare earth drum magnetic separators.

Carrier magnetic separation has been proposed for more effective separation of water and solids from acid mine water to generate very pure water (Feng et al., 2000). As discussed in Chapter 10, dissolved heavy metals like zinc and copper can be recovered from acid mine drainage (AMD) by selective precipitation controlling the pH for the precipitation of specific metals. Following this recovery step, the remaining solution is treated with lime to a pH ~12 to precipitate the residual metal ions. The water thus produced is satisfactory for recycling in mineral processing, but not of the quality for domestic use as it still contains some heavy metal ions. That is because, some of the metal hydroxides are amphoteric and their hydroxides re-dissolve at very high pH. For example, the concentration of lead ion increases from nearly zero at pH 9 to 0,12mg/L at pH 12 as the precipitated lead hydroxide dissolves producing plumbate:

Magnetic filtration has been applied in place of lime treatment by Feng and coworkers (2000). Ultrafine magnetic particles are used as magnetic seeds. At a dosage of 0.5 g/L magnetite, all fine precipitate flocs can be rendered strongly magnetic. The mine water is treated with hydrogen peroxide (to oxidize ferrous iron and manganese), followed by the addition of lime and magnetite to raise the pH to 5, Sodium sulfide and more lime are then added to raise the pH to 8. The heavy metal sulfide precipitates are filtered magnetically using a high gradient magnetic separator with a permanent magnetic assembly. This produces an effluent with heavy metal ion (Cu, Zn, Pb, Cd, Cr, Mn, Ti,) well below the discharge limits. The effluent thus freed from heavy metals is then passed to an ion exchange step, where the calcium ion is removed by a cationic resin and sulfate ions by an anion exchange resin. In the elution step, the cation resin is treated with sulfuric acid and the anion resin is treated with sodium hydroxide and lime. High quality gypsum (calcium sulfate) is produced by both elutions. This is a useful byproduct, which helps to offset the cost of the process for the effective removal of toxic metal ions.

A similar process to separate various metal ions in acid mine water by magnetic seeds has been described by Choung and coworkers (2000). In their laboratory study the metal ions are precipitated as hydroxides and magnetite is added as a magnetic seed. The metal hydroxide precipitates are thought to be locked by the magnetic seed, which is then separated by a hand magnet.

The technique has so far been demonstrated only on a laboratory scale. While it may have considerable potential in removing toxic metals from relatively dilute streams of acid mine water, it has not been applied on a pilot plant scale. Economic factors, in particular, the quantity of magnetite required for large scale treatment is an important factor to be considered.

Lyman and Palmer (1993b) studied the roasting(magnetic separation or selective leaching process). The roasting here aimed at oxidizing neodymium while leaving iron as metallic form at a controlled H2water vapor mixture on the basis of the thermodynamic consideration showing a common stability region of Nd2O3 and Fe. Although selective roasting was successful, the subsequent process such as magnetic separation and acid leaching were not because of the extremely fine grain size of the oxidized scrap. Thus, they discontinued the study in this direction and changed the strategy to total dissolution process as has been described previously.

When large quantities of ferrous scrap are to be separated from other materials magnetic separation is the obvious choice. The two types of magnets are permanent magnets and electromagnets. The latter can be turned on and off to pick-up and drop items. Magnetic separators can be of the belt type or drum type. In the drum a permanent magnet is often located inside a rotating shell. Material passes under the drum on a belt. A belt separator is similar except that the magnet is located between pulleys around which a continuous belt travels. Magnetic separation has some limitations. It cannot separate iron and steel from nickel and magnetic stainless steels. Also, composite parts containing iron will be collected which could contaminate the melt. Hand sorting may be used in conjunction with magnetic separation to avoid these occurrences. (See Chapter 3 for discussion of magnetic separation techniques).

Nickel is mainly extracted from its sulfide ores which are concentrated by magnetic separation and a froth flotation process. After concentration by these processes the concentrated ore is mixed with silica and subjected to a number of roasting and smelting operations. During these operations the iron and sulfide contents are reduced by their conversion first into oxide and then to silicate, which is then removed as slag. The resulting matte of Ni3S2 and Cu2S is allowed to cool for few days, when Ni3S2, Cu2S, and nickel/copper metal form distinct phases which can be separated mechanically. The metal is obtained from the matte electrolytically by casting it directly as an anode with a pure nickel sheet as a cathode and aqueous NiCl2, NiSO4 as an electrolyte. At a temperature of around 50C and at atmospheric pressure, the obtained nickel, which is impure, is then reacted with the residual carbon monoxide to produce the volatile nickel tetra carbonyl which gives back the pure metal and carbon monoxide at 230C.

Adsorption using magnetic adsorbents has emerged as an exigent water remediation technology particularly for wastewater treatment while eliminating filtration shortcomings of nonmagnetic adsorbents. Magnetic separation not only simplifies isolation but also opens the ground for easy washing followed by redispersion. Moreover, mechanisms controlling the adsorption process are also enhanced. Pyrolysis, coprecipitation, and calcination are the methods frequently used for preparation of good-quality and high yield of magnetic biochar (Thines et al., 2017).

Conventional heating and microwave-assisted heating have been used in laboratory scale to generate magnetic biochar adsorbents. Conventional pyrolysis has been successfully integrated in industrial production of magnetic biochars using modified furnace. Cottonwood, pinewood, date pits, pine needles, hydrochar waste, orange peels, and pine bark underwent conventional pyrolysis after being treated with magnetic precursors like FeCl36H2O, Co(NO3)26H2O, natural hematite, Fe(NO3)39H2O, etc., to create magnetic biochars (Yang et al., 2016; Zhu et al., 2014; Zahoor and Ali Khan, 2014; Harikishore Kumar Reddy and Lee, 2014; Wang et al., 2015c; Zhang et al., 2013a,d; Theydan and Ahmed, 2012; Chen et al., 2011a; Liu et al., 2010). All these magnetic biochars used for adsorption of phosphate, arsenate, methylene blue, aflatoxin B1, triclosan, Cd2+, Pb2+, and metallic Hg showed improved performance in magnetic response and adsorptive removal from aqueous phase due to incorporation of the more active sites required for adsorption and enhanced physical properties. This can be attributed to uniform and dispersive reinforcement of -Fe2O3, Fe3O4, and CoFe2O4 forming strong mechanical bonds with biochar matrix. The oxide particles embedded showed particle size within 20nm to 1m with variable shapes such as cubic or octahedral. However, reduction in surface area (Wang et al., 2015c; Zahoor and Ali Khan, 2014; Chen et al., 2011a) and lowered adsorption capacity upon reinforcement of magnetic oxide (Khan et al., 2015) did not appear significant indicating minimum hindrance in adsorptive removal of pollutants by these composites.

Microwave-assisted pyrolysis has also found its way in the production of magnetic biochars from bamboo and empty fruit branch used for the remediation of Cr(VI), Cd2+, methylene blue, and Pb2+ from aqueous phase (Ruthiraan et al., 2015; Mubarak et al., 2014; Zhang et al., 2013d; Wang et al., 2013, 2012, 2011). These magnetic biochars containing hydrous Fe2O3, cobalt oxide, binary CoFe oxide, and metallic Ni crystals adsorbed these contaminants through electrostatic attraction, ion exchange, inner sphere surface complexation, and physisorption. Superparamagnetic cotton fabric biochars were obtained following both conventional pyrolysis and microwave-assisted pyrolysis by ZHu et al. (2014) in order to compare their properties. The authors found that microwave-heated biochar showed no apparent agglomeration and was characterized by more controlled size and dispersion of oxide particles. Modification of magnetic biochar to further improve its functionality has also been reported. For example, chitosan modification of magnetic biochar obtained from invasive species Eichhornia crassipes provided more oxygenated functional groups for greater electrostatic interaction and therefore enhanced Cr(VI) remediation (Zhang et al., 2015a).

Coprecipitation is another process by which magnetic biochar can be fabricated. Yu et al. (2013) employed sugarcane bagasse as the raw material for the production of magnetic-modified sugarcane bagasse through the chemical precipitation of Fe2+ and Fe3+ over the sugarcane bagasse particles in an ammonia solution under ultrasound irradiation at 60C. A large amount of carboxyl groups found on the surface of biochar, which made the surface more negatively charged. Thats why better adsorption was found for the removal of Pb2+ and Cd+ due to the ion-exchange mechanism (Yu et al., 2013). A comparison of two synthesis methods including chemical coprecipitation of iron oxides onto biochar after pyrolysis and chemical coprecipitation of iron oxides onto biomass before pyrolysis for preparing magnetic biochars was studied by Baig et al. (2014). The results suggested that the chemical coprecipitation of iron oxides before pyrolysis led to greater Fe3O4 loading, higher saturation magnetization, improved thermal stability, and superior As(III, V) adsorption efficiency of the biochars (Baig et al., 2014).

Magnetization in biochar can also be introduced via calcination in which biochar is subjected to heat treatment to remove water and drive off CO2, SO2, and other volatile constituents. The simplicity of this process was the main reason behind the wide application of this process in the production of magnetic biochar composites. For instance, calcination of rice hull and ferric acetylacetonate in tube furnace generates magnetic biochar consisting of good dispersion of Fe3O4 particles on the surface. The biochar showed improved lead removal performance through hydroxide precipitation followed by suitable magnetic separation.

Magnetic mineral separation techniques are invariably selective, and not fully representative of the grain size and composition of magnetic minerals present in the sample; however, magnetic separation may be necessary for SEM/TEM, X-ray, Mossbauer, or chemical analyses. The importance of fine SD grains as remanence carriers emphasizes the necessity of making the separation technique as sensitive as possible to the fine grains. As grain shape has become an important criterion for distinguishing detrital and biogenic magnetite, separation procedures to prepare representative extracts for SEM and TEM observation have become more important. A recommended procedure which has been successful for extracting magnetite (including the SD fraction) is as follows: (i) Crush the sample (if necessary) in a jaw crusher with ceramic jaws, (ii) Use a mortar and pestle to produce a powder. (iii) Dissolve carbonate with 1N acetic acid buffered with sodium acetate to a pH of 5, changing the reagent every day until reaction ceases (several weeks), (iv) Rinse the residue with distilled water, (v) Agitate the residue ultrasonically in a 4% solution of sodium hexametaphosphate to disperse the clays. (vi) Extract the magnetic fraction using a high-gradient magnetic separation technique (Schulze and Dixon, 1979), or alternatively, pass the solution (several times, if necessary) slowly past a small rare earth magnet.

Seed receipt and preparation: Following receipt, the seeds are sent for mechanical preparation. This consists of mechanical screening and magnetic separation to remove any impurities which may be present. Following separation are the processes of crushing, flaking, and cooking.

Oil Extraction: The prepared seeds are mixed with hexane in a continuous counter current system to produce a hexane-oil mixture (miscella) and seed cake. The seed cake is separated from the miscella, dried cooled, pressed, and used to produce animal feed. The hexane is recovered from the miscella under vacuum (using direct and indirect steam) and reused in the system. The remaining crude oil is then cooled and sent for refining.

Oil refining packaging: Crude oil and ghee are processed using the following steps:Degumming (for sunflower seeds or soybean) and neutralization gums are removed in a batch process, using phosphoric acid. Neutralization is done by adding caustic soda to remove free fatty acids from crude oil to produce semi-refined oil.Bleaching color is removed from the oil using fuller's earth followed by filtration.Deodorization unpleasant odours are removed from oil by high temperature vacuum distillation.Packaging the reined, bleached, and deodorized (RBD) oil is bottled in automatic filling lines.

Degumming (for sunflower seeds or soybean) and neutralization gums are removed in a batch process, using phosphoric acid. Neutralization is done by adding caustic soda to remove free fatty acids from crude oil to produce semi-refined oil.

Soap and glycerin production: Fats are saponified in a batch process, by mixing with caustic soda and heating with direct and indirect steam. After saponification, soap is separated from the lye solution to be dried, blended with additives, homogenized, cut, and pecked. Glycerin is separated from the lye solution and distilled.

The two main sources of energy are mazot and electricity. Mazot and solar are used in the boilers to generate steam. Average annual consumption 15,000 tons of mazot and 600 tons of solar. Annual electricity consumption is around 10.5 million kWh.

The factory consumes an average of 16,800 m3/day of water of which 1,800 m3/ day is process water, and 1,500 m3/day cooling and vacuum water. This water is taken entirely from group water boreholes within factory premises. Approximately 35 m3 of drinking water is taken from the public network every day.

The factory generates about 16,000 m3/day of industrial wastewater from different factory steams, including process effluents, boiler blow down, cooling water, vacuum water, and steam condensate. The wastewater is discharged to Akhnawy drain near the factory.

Iron-containing residues generated in steel plants contain several toxic elements and require further processing In an integrated process described by Eetu-Pekka and coworkers (2005) the residues go through a magnetic separation step. In the second stage they are agglomerated, before the reduction of iron oxides. The element, which is most problematic is sulfur. Some of it is transferred in to the gas phase during reduction as hydrogen sulfide and carbonyl sulfide (COS). There would still be a large amount of sulfur in the residue after the reduction phase. One way to decrease the amount of sulfur is to separate the residues with high sulfur content before the processing and leave them outside of recycling. Other possible methods suggested are to enhance the transfer of sulfur into the slag phase by controlling the slag composition or by ensuring the carbon saturation of iron. The slag composition can be controlled to enhance the transfer of sulfur by addition of lime to the residue material. Excessive lime should be avoided to prevent precipitation of solid phases like dicalcium silicate. Sulfur content of iron can be lowered by increasing the carbon and silicon content in metal, by adding carbon into the residue material. Optimum quantity depends upon the original composition of the residue material. The process is schematically shown in Figure 8.25

MWI-bottom ash is the solid residue from combustion of municipal waste or in a Municipal Waste Incineration Furnace. Often MWI-bottom ashes have been subjected to a post treatment consisting of magnetic separation of iron and sieving and comminution of particles > 40 mm. Fly ashes from Municipal Waste Incineration are kept separate from the MWI-bottom ash. In the Dutch situation it is forbidden to prepare mixed ashes from fly ash and bottom ashes. In 1996 800,000 tons of MWI-bottom ash were produced in the Netherlands. The last years MWI-bottom ash is utilized for 100%, primarily in granular form as embankment material up to a hight of 10 m or more or as a road base material.

MWI-bottom ashes are supplied to the market with a certificate for its technical and environmental behaviour. The environmental part of this certificate is based on old legislation. MWI-bottom ashes up to now always comply with the demands for environmental certification.

The Building Materials Decree enforces more severe demands than the present regulations. Because of that a large part of the MWI-bottom ashes does not comply with the demands from the Building Materials Decree. To safeguard its outlet to the market the Dutch Ministry of the Environment has developed a Special Category for MWI-bottom ashes. In this category MWI-bottom ashes can be utilized under a set of isolation measures. With the Municipal Waste Incineration sector the appointment has been made to pursue steady quality improvement of its byproducts so that MWI-bottom ashes can be utilized as Category 2 Building Materials in future.

study on magnetic materials for removal of water pollutants | intechopen

study on magnetic materials for removal of water pollutants | intechopen

Open Access is an initiative that aims to make scientific research freely available to all. To date our community has made over 100 million downloads. Its based on principles of collaboration, unobstructed discovery, and, most importantly, scientific progression. As PhD students, we found it difficult to access the research we needed, so we decided to create a new Open Access publisher that levels the playing field for scientists across the world. How? By making research easy to access, and puts the academic needs of the researchers before the business interests of publishers.

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Water is a primary element for all living things, and we need water for each and every day-to-day activity related to agricultural, industrial, and domestic cares and, thus, its quality influences all aspects of human life including energy, food, health, and economy. Safe drinking water is our primary need to protect our life and thus developing efficient and affordable techniques for water treatment to access potable water to the humanity. Water pollution is one of the severe environmental and health problems worldwide. Pollutants in water can be of organic, inorganic, heavy metals, microbial, and radioactive species, which may be in different forms viz. suspended, dissolved, or dispersed materials. The water quality is mainly affected by industrial discharges, agricultural activities, mismanagement of hazardous materials, etc. Nowadays, nanotechnology offers the possibility of an efficient removal of water pollutants including metals, organic dyes, bacteria, parasites, etc. Magnetic nanomaterials like iron oxide (Fe3O4) are very promising materials used in water decontamination particularly for heavy metals and dyestuffs because of their ease of separation through external magnet, high surface area, unique morphology as well as their high stability. These materials can be used as adsorbent, photocatalyst, and coagulating agents for water remediation based on their composite materials or surface functionalities.

Water, i.e., 2 mol of hydrogen and 1 mol of oxygen or simply called H2O plays a vital role in our everyday life. Without water no one can think of life on earth. About 71% of earth is covered with water. Of that 71% water about 97% resides in oceans and only 3% of water is fresh water (Figure 1a) and of that 3% about 68.7% of freshwater is locked up in icecaps and glaciers (Figure 1b), and it is quite a surprising fact that almost all the remaining fresh water is below the ground. Of all the freshwater on the surface of earth only 0.3% is contained in fresh lakes, and rivers [1].

As the population is increasing day by day the water availability per capita is decreasing. So the challenge of limited amount of freshwater and its decreasing per capita availability is an issue of concern but another major challenge is water pollution that has not only environmental impact but also have a major effect on human health. As per the statistics 783 million people do not have access to clean and safe water worldwide [2]. Around 319 million people in Sub-Saharan Africa are without the access to improved reliable drinking water sources. One in nine people worldwide do not have access to safe and clean drinking water. 443 million school days are lost each year due to water-related diseases [3]. In developing countries, as much as 80% of illnesses are linked to poor water and sanitation conditions [4]. 2.6 billion people in the world lack adequate sanitation and which contributes to about 10% of the global disease burden [5]. Half of the worlds hospitals beds are filled with people suffering from a water-related disease [6].

As we have seen that the contaminated water has a very bad impact on human health even some heavy metals that if taken for long time it can cause cancer such as arsenic is considered as one the carcinogenic contaminant in water. After understanding the health issues related to contaminant water there is need to understand the source of contamination and major contaminants that pollute the water.

In recent years, magnetic materials have been potentially used for removal of water pollutants, particularly organic contaminates (dyes, chlorinated hydrocarbons, aromatics), pesticides, as well as heavy metals [10]. There are a large number of techniques available for water treatment for safe drinking water including adsorption, precipitation, solvent extraction, ion exchange, reverse osmosis, membrane separation, evaporation, and photocatalysis. The development of nanoscience and nanotechnology shows their potentiality in removing toxic elements from water bodies with better water treatment process. The design and development of nanomaterials which belong to the size range of 1100nm exhibiting unique properties as compared to the bulk materials leads to the enormous improvements in many sectors including, health, manufacturing, electronics, environmental remediation as well. The magnetic nanomaterials (paramagnetic or ferromagnetic or superparamagnetic) with tailored surface chemistry have already expanded their scope of application in water treatment. In this chapter, various processes of drinking water treatment and waste water treatment using advanced magnetic materials in removing toxic metal ions, organic and inorganic solutes, bacteria and viruses has been discussed.

There are many sources of drinking water and the main sources are ground water, lakes, canals, reservoirs, rain water, fog water and sea water. These sources are contaminated in different ways and broadly the source of contamination can be divided in to two categories:Direct sources or point sourcesIndirect sources or non-point sources

Direct sources basically include effluent from industries, treatment plants, refineries, factories, etc. However, indirect sources or non-point sources include the water contamination entering to the water body through a number of processes, e.g., while putting the fertilizers and pesticides to the agricultural field, the elements presents in the chemical percolates down to the groundwater and ultimately pollute the water.

Organic contaminants present in drinking water create severe problem on human health. Pollution by organic chemicals in water bodies occurs by various mechanisms. Industrial waste containing various organic chemical contaminants pollutes the water bodies. Volatile organic compounds (VOCs), pesticides, phenolic compounds, phthalates, and nitrogen-containing compounds, are often detected in polluted water [11]. Many of these compounds have been found to be carcinogenic, even in very low concentrations. WHO Guidelines for drinking water quality, levels are set for 28 organic constituents (i.e., microcystin-LR, chlorinated alkanes, chlorinated benzenes and miscellaneous), 33 pesticides, and 9 disinfectant by-products, due to their health effects on humans [12]. It is noteworthy to mention that, occurrence of pharmaceutical and personal care products and perfluoroalkyl acids in aquatic environment has been recognized as emerging issue in environmental chemistry [13].

Inorganic contaminants include metals, salts and other compounds that do not contain carbon. Many of them are naturally occurring and should be considered as an integral part of those waters, e.g., calcium carbonate and bicarbonate in hard water. The metal ions such as Hg(II), Pb(II), Cr(III), Cr(VI), Ni(II), Co(II), Cu(II), Cd(II), Ag(I), As(V) and As(III) are toxic from eco toxicological point of view. Besides, the pollution by the radioactive elements is of major concern looking into their long-term hazardous impacts.

Pathogens such as bacteria, viruses and parasites may be present in very low concentration in drinking water; but cause many infectious diseases and are considered as one of the major risk factors with drinking water safety [14]. The pathogenic microorganisms enter in to water body through sewage discharge as a major source or through the wastewater from industries like slaughterhouses. Water-borne pathogens have been the causes of many disease outbreaks such as diarrhea, cholera, gastro-intestinal illness [15]. The recurrence of water-borne pathogens is due to a number of reasons like heavy water contamination, population explosion, change in potable water treatment methods, globalization of commerce and travel. It has been made possible to detect pathogen based water contamination to a large extent owing to the improved methods for detection and source tracking [16, 17]. The most serious health risk is related with ingestion of water which is contaminated with fecal matter and the discharge of wastewater into various ambient water bodies is what contributes to the multiplication of numbers of such pathogens (bacteria, viruses, protozoa and helminthes) [18].

Water treatment is defined as the removal of the above contaminants using some specific process. In most of the water treatment processes, conventional adsorption process with activated carbon is adopted and the adsorption capacity is substantially decreased in presence of high concentration of organic matters in water where the active sites are mostly occupied by these materials. In recent times, there are various technologies have been employed for the removal of water contaminants such as filtration (ceramic, bio sand, membrane, and activated carbon based filtration), heat and UV radiation, chemical treatment (coagulation-flocculation, chemical disinfection), and desalination (reverse osmosis, distillation). The various techniques in water treatment can categorized into following six classes [19]:AdsorptionBiotechnologyCatalytic processesMembrane processesIonizing radiation processesMagnetically assisted processes.

There are specific advantages and disadvantages for a particular process. The nanotech based processes are promising option in current water treatment processes because of their target specificity, ease of separation, high adsorption per unit area, as well as less maintenance.

There has been increased interest in using magnetic materials in water treatment which are basically composed of magnetic core of iron oxides organic compounds, carbon materials, etc. Recently, nanomaterials in different shapes, morphologies, forms, e.g., metal-containing nanoparticles, carbonaceous nanomaterials, zeolites, dendrimers, carbon nanotubes, nanofibers have been used for water purification [20]. However, the difficulty arises in using these materials is the separation of solid materials from liquid and which is more difficult as the particle size decreases in nanoscale. On the other hand, the using of magnetic, particularly the magnetic nanoparticles (MNPs) materials have the advantage of magnetic filtration in separation of solid from liquid and are more efficient [21].

However solid/liquid (S/L) separation is more difficult as the particle size decreases. On the other side, in case of magnetic sorbents based on Fe oxides, the magnetic filtration may be applied for S/L separation. Furthermore, the removal of particles from solution with the use of magnetic fields is more selective and efficient (and often much faster) than centrifugation or filtration (Yauvuz et al.) [21]. Here are the advantages of using MNPs adsorbent for water treatment processes:Small size and thus high surface to volume ratioSolid/liquid separation through magnetic filtration is selective, faster than centrifugation and filtration techniquesReusabilityGreater biocompatibilityMagnetic separation

Different types of magnetic materials have been synthesized and designed for development of advanced materials and applied effectively in widespread uses such as biomedicine, magnetic resonance imaging (MRI), catalysis, spintronics, robotics, engineering, environmental remediation, etc. [22] There are different synthesizing methods viz. co-precipitation, solvothermal, hydrothermal, microemulsion, sonochemical, etc. which determine their particle size, distribution, morphology, surface functionality, and magnetic properties and in turn of their various application [22]. Magnetic materials are made from mixtures of metals of iron, cobalt, nickel, and alloys and their oxides (of the type MFe2O4, where M is a metal). Out of these materials, iron (zero valent iron) and its oxides, i.e., usually -Fe2O3 (maghemite) and Fe3O4 (magnetite) nanoparticles have attained significant interest in recent years and have been used for water treatment processes. The various composite magnetic materials such as [email protected] [23, 24], [email protected] [25], [email protected] [26], [email protected] (poly(propylene oxide)), PEO (poly(ethylene oxide) [27], [email protected] (polydopamine) [28], [email protected] (poly(N-isopropylacrylamide)) [29], [email protected] (molecularly imprinted polymer-encapsulated particles) [30], [email protected] (multi-walled carbon nanotubes) [31], [email protected] (carbon spheres) [32], Fe/iron oxide-oxyhydroxide/rGO (grapheme) [33], etc. have been used for environmental applications. Singh and his co-workers synthesized a series of magnetic nanocomposites such as CoFe2O4ZnS [34], [email protected] (green tea polyphenols) [35], Fe3O4Cr2O3 [36], CoFe2O4-Cr2O3-SiO2 [37] and applied for wastewater treatment.

In addition to their suitable magnetic properties, i.e., ferrimagnetic, ferromagnetic and superparamagnetic (nanoparticle size less than 10nm), their synthesis procedure is simple and cost-effective and they can be easily functionalized as desired for many applications. The size and shape and magnetism of these magnetic materials can be easily controlled based on their application and thus they can be easily dispersed in liquid medium and their stability can be retained for multiple uses. Moreover, these materials are non-toxic or less toxic, chemically inert, thermally stable as well as biocompatible.

Appearance of water pollution as a global threat demands the development of low-cost and reliable materials for effective waste water remediation. The magnetic materials have been used for clean water technology for both in laboratory as well as field scale [38, 39]. In recent years, iron oxide nanomaterials have been used as adsorbent or immobilizing agent and photocatalyst or the both depending on nature of contaminants in water [40].

Heavy metal contamination in water such as cadmium, zinc, lead, chromium, nickel, copper, vanadium, platinum, silver and titanium due to industrial activities is significantly increasing which is detrimental to human beings and animals. Magnetic nanomaterial adsorbents have been potentially used for removal of metallic ions such as Cr(VI), Cu(II), Co(II),Cd(II), As(V), As(III) and Hg(II) in water [41, 42] which are more effective as compared to micron size particles. The magnetic chelating resin based materials have been used for effective removal of Cu(II), Co(II), and Ni(II) ions [43]. The magnetic hydrogels based on 2-acrylamine-2-methyl-1-propansulfonic acid can be used for removal of many heavy metal ions such Cd(II), Co(II), Fe(II), Pb(II), Ni(II), Cu(II) and Cr(III) from water in repeated cycles [44]. The Cu(II) can also be effectively removed by functionalized mesostructured silica containing magnetite [45]. The acrylate-based polymer composites with magnetite can be used in selective removal of heavy metals from water (selectivity: Cu>Cr>Zn>Ni) [46]. Layered double hydroxide (LDH) prepared from Fe3+ and Ni2+ shows good adsorption of As and subsequent magnetic separation [47]. The magnetic zeolite composites are used for decontamination of heavy metals from water [48]. The composite materials of mesoporous magnetic MCM-41 with aminopropyls are used for selective removal of As(V), and Cr(VI) in presence of Cu(II) [49].

Magnetic nanoparticles are used as an adsorbent for the removal of various dyes and dyes stuff from aqueous solution. Removal of dyes from waste water has become a serious issue of concern because of its harmful impact on human. Dyes basically can be classified in to two categories, i.e., anionic dyes and cationic dyes.

Long et al. [50] synthesized [email protected]/polyethylenimine (PEI) nanoparticles and tested for adsorption of three different kind of anionic dyes, i.e., methyl blue, orange G and amaranth and found the maximum adsorption capacities of 344.8, 192.3 and 146.2mg/g, respectively. Saksornchai et al. [51] synthesized magnetite (Fe3O4) coated with cetyltrimethylammonium bromide (CTAB) and tested for the adsorption of anionic dye Congo red (CR) removal. They found maximum adsorption capacity for CR dye to be 93.46mg/g. Faraji et al. [52] synthesized triazine-based nitrogen-rich network-modified magnetic nanoparticles were synthesized for the adsorption of methyl orange. Sahraei et al. [53] reported the synthesis of magnetic bio-sorbent hydrogel beads based on modified gum tragacanth/graphene oxide for the removal of heavy metals and dyes from water. They found the adsorption capacity of 101.7mg/g for Congo red dye. Ge et al. [54] fabricated [email protected] magnetic nanocomposites for the removal of heavy metal ions and dye from water. They found that the synthesized nanocomposite showed excellent adsorption capacity of 6947.9mg/g for methylene orange. Wu et al. [55] fabricated multi-functional magnetic nanoparticle core covered with polyethylenimine (PEI) derived quaternary ammonium compounds (QAC) corona through electrostatic attraction for the removal of dyes and metal ion adsorption. The adsorption results corresponding to synthesized nanoparticle showed the maximum adsorption capacity of 653mg/g for AF as a representative of dyes. Konicki et al. [56] synthesized [email protected] core shell nanocomposite for the removal of anionic dyes from aqueous solution. The synthesized nanoparticles were tested for the adsorption of two anionic dyes namely acid red 88 (AR88) and direct orange 26 (DO26) and the maximum adsorption capacity was found to be 63.7mg/g and 42.7 for AR88 and DO26, respectively. Zhang et al. [57] synthesized the Fe3O4 nanoparticle modified with 3-glycidoxypropyltrimethoxysilane (GPTMS) and poly-lysine (P-Lys). They found that the synthesized MNPs could effectively remove anionic dyes including methyl blue (MB), orange I (OR-I), amaranth (AM) and acid red 18 (AR-18) from water solution.

Cationic dyes are most toxic because they can easily interact with negatively charged cell membrane surfaces, and also they can enter in to the cells and can concentrate in cytoplasm (Bayramoglu et al.) [58]. Ge et al. [59] have studied the adsorption of cationic dyes such as crystal violet, methylene blue and alkali blue 6B from aqueous solutions by use of polymer-modified magnetic nanoparticles. The cationic dyes could be quickly removed from water solution with high efficiency at pH512. More significantly, the MNP showed high efficiency as a reusable adsorbent for fast and convenient removal of cationic dyes from water solution. Yan et al. [60] have synthesized full biodegradable magnetic adsorbent based on glutamic acid modified chitosan and silica coated Fe3O4 nanoparticles for removal of three different kinds of cationic dyes, methylene blue, crystal violet and cationic light yellow 7GL, from aqueous solutions. Chen et al. [61] have prepared magnetic adsorbent by fabrication of chitosan/polyacrylic acid multilayer onto magnetic Fe3O4 microspheres for removal of adsorption of two cationic dyes, methylene blue and crystal violet from aqueous solution. Amiri et al. [62] synthesized cobalt ferrite silica magnetic nanocomposite for the adsorption of Malachite green dye and found the adsorption capacity of 75.5mg/g for that dye. Li et al. [63] synthesized wettable magnetic hypercrosslinked microporous nanoparticle for the water treatment. The synthesized nanoparticle consists of microporous organic polymer which combine sodium acrylate functionalized hypercrosslinked polymer with magnetic Fe3O4 nanoparticle to form a hybrid. They tested the synthesized hybrid for the adsorption of Rhodamine B dye and found the maximum adsorption capacity of 216mg/g. Singh et al. [64] had synthesized the superparamagnetic nanoparticles coated with green tea polyphenol by wet chemical method. They found that the particles have a very high adsorption capacity of (7.25mg/g) for removal of methylene blue (MB) dye in wastewater treatment. Li et al. [65] synthesized magnetic peach gum bead bio-sorbent for the adsorption of MB dye and found the maximum adsorption capacity of 231.5mg/g.

The presence of pharmaceuticals such as antibiotics, anticonvulsants, antipyretics drugs, hormones in surface and ground water possesses a major environmental challenge. Their contamination even at trace amount is a serious concern to the aquatic organisms as well.

Attia et al. [66] synthesized magnetic nanoparticles coated zeolite for the adsorption of pharmaceutical compounds from aqueous solution. They found that the synthesized magnetic nanoparticles can remove more that 95% of PPCPs in 10min. Reddy et al. [67] reviewed spinal ferrite nanoparticles and found that SF and its derivatives can be used for remediation of various pollutants. Nadim et al. [68] Synthesized gallic acid coated magnetic nanoparticles (GA-MNP) and used as a photocatalyst for degradation of meloxicam; a commonly prescribed nonsteroidal anti-inflammatory drug.

Recently, M. Hayasi and his coworker described the use of magnetic poly (styrene-2-acrylamido-2-methyl propanesulfonic acid) (St-AMPS) as adsorbent for removal of the pharmaceuticals viz. ceftriaxone sodium, diclofenac sodium, and atenolol from water [69].

Xu et al. [82] demonstrated that poly-allylamine-hydrochloride (PAAH) stabilized magnetic nanoparticles are powerful tools to remove pathogenic bacteria from drinking water with high efficiency and no significant toxicity was observed in the MNPs treated water. Over 99.5% of the pathogens (four main pathogens viz. Escherichia, Acinetobacter, Pseudomonasand Bacillus) can be removed when the bacterial count was less than 105CFU/mL.

Zhang et al. [83] synthesized magnetic nanoparticle coated with Cu doped MgO through a hydrophilic carbon layer ([email protected]@MgO-Cu). They found its potential application as disinfectant in water purification by examining the antibacterial activity of the [email protected]@MgO-Cu composite toward Gram-negative Escherichia coliand Gram-positive Staphylococcus aureus.

Zhang et al. [84] synthesized magnetic poly-N,N-[(4,5-dihydroxy-1,2-phenylene)bis(methylene)]bisacrylamide) (POHABA)-based core-shell nanostructure on the Fe3O4 core surface ([email protected]). The magnetic nanocomposite, [email protected] can be used in domestic water treatment against bacterial pathogens.

Rana et al. [85] synthesized ferromagnetic Ni-doped ZnO nanoparticles and applied as an antibacterial agent to control the growth of bacterial pathogens. They found the as synthesized material to be very effective against water related bacteria such as E. coliand V. cholera.

Shukla et al. [86] synthesized the iron oxide nanoparticles coated with chitosan oligosaccharide and used for the removal of pathogenic protozoan cysts, entamoeba cyst (which causes amebiasis) from water. They found that E. histolyticacan be efficiently captured using the magnetic nanoparticles from contaminated water.

Zhan et al. [88] synthesized the amine-functionalized magnetic nanoparticle (Fe3O4-SiO2-NH2) and used for rapid removal of pathogenic bacteria and viruses. The magnetic materials can be effectively used to capture a wide range of pathogens including various bacteria such as S. aureus, E. coliO157:H7, P. aeuginosa, Salmonella, and B. subtilis.

Park et al. [89] developed a novel magnetic hybrid colloid (MHC) decorated with varying sized Ag nanoparticles. The MHC was prepared as a cluster of superparamagnetic Fe3O4 coated with silica shell. The MHC decorated with the Ag nanoparticle of 30nm size ([email protected]) exhibited the highest antimicrobial efficacy toward E. coliCN13 (6-log reduction) and the bacteriophage MS2 (23 log reduction).

Magnetic water treatment (MWT) is a new technique which is promising in environmental remediation in addition to its increased application in the area of medicine, agriculture and industrial process. The water molecules acquire unique physicochemical characteristics under the influence of the magnetic fields (MFs). It is a non-chemical method and the water molecules undergo change from their cluster of many loosely bound water molecules into very small, uniform and hexagonally organized clusters of molecules under the magnetic treatment [90]. These features of the magnetized water prevent the polluting agents to enter in to its cluster and also make their easy passage through the cells of plant as well as of animals. Moreover, the MFs have antimicrobial activity on water. Therefore, the magnetized water molecules depict as bio-friendly and eco-friendly compounds to environmental management as well as to plant and animal cells.

While taking sustainability in to consideration there are various factors over which it depends. Important factors include environmental impact on use of MNPs, toxicity associated with the MNPs, reusability, reactivity, adsorption capacity, biocompatibility, stability, etc. For example, uncoated nanoparticles are associated with some toxicity while coating can help them to make non-toxic. Similarly, their regeneration and reusability are the main factors for making them technically more viable and economically sustainable materials for commercial uses.

In this chapter the removal of water pollutants by using magnetic materials of zero valent iron, magnetite (Fe3O4), maghemite (-Fe2O3) as adsorbent, photocatalyst and coagulants have been described. The MNPs have been used in removal of water pollutants through their various surface functionalities (e.g., coating with polyphenols, amino acids, sugars, alkaloids, terpenoids, proteins, carbonyl, carboxyl, carbon, polysaccharides, and semiconductors) with desired size and shapes, and magnetic behavior. Looking in to the fast development of magnetic materials in different technological and scientific fields, magnetic nanomaterials appear to be extremely promising for water and wastewater treatment. The waste water treatment methods using these materials are fast, non-toxic, and eco-friendly as compared to the available physic-chemical treatments which make it attractive for materializing commercially. Their magnetic nature makes them attractive for waste water treatment because of their easy separation from aqueous medium after purification and can be reused in repeated treatment cycles. However, research for bulk production, controlling morphology, optimizing surface functionality and their stability, and biocompatibility should be essentially considered prior to commercial application from laboratory scale. Moreover, further studies needs to be addressed to detail mechanism of magnetic nanomaterials in water treatment. The magnetic nanoparticles and their composites with their high surface to volume ratio offer more surfaces for chemical as well as physical adsorption and thus show high reactivity which gives the prospects of using these materials in large scale removal of emerging water pollutants.

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what is magnetic separation? (with pictures)

what is magnetic separation? (with pictures)

Magnetic separation is an industrial process where ferromagnetic contaminants are recovered from materials on the production line. Manufacturers use this to extract useful metal, separate recycling, purify materials, and perform a wide variety of other tasks. Manufacturers of magnetic separation equipment may have a range of products available for sale for different applications, including an assortment of sizes with strong and weak magnetic fields to attract different kinds of magnetic material.

The magnetic separator consists of a large rotating drum that creates a magnetic field. Materials enter the separator and fall out through mesh at the base if they are not magnetic. Sensitive particles respond to the magnetism and cling to the sides of the container. The drums can be used in continuous processing of materials as they move along the assembly line, or in batch jobs, where a single batch is run through all at once.

One common use for magnetic separation is to remove unwanted metal from a shipment of goods. Magnetic separation can help companies keep materials pure, as well as remove things like nails and staples that may have crept into a shipment. The equipment can also purify ores, separate components for recycling, and perform a variety of other tasks where metals need to be separated or isolated. Equipment can range in size from a desktop unit for a lab that needs to process small amounts of material to huge drums used in scrap metal recycling centers.

Manufacturers of magnetic separation equipment typically provide specifications for their products for the benefit of prospective customers. Consumers may need equipment that targets a specific range of metals, or could require large size or high speed capacity. It may be possible to rent or lease equipment for some applications, or if a factory wants to try a device before committing to a purchase. Used equipment is also available.

A gentler form of magnetic separation can be used for delicate tasks like removing magnetic materials from cremated remains or finds at an archaeological site. In these situations, a technician carefully moves a magnet over the material to pull out materials like staples and jewelry. At a crematorium, this is necessary before ashes are ground, as metal objects can damage the equipment. For archaeologists, it can provide a mechanism for carefully separating materials at a find and documenting the position and location of various objects as the archaeologist uncovers them on site or in a lab.

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a InfoBloom researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a InfoBloom researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

@allenJo - I do believe they use these systems in water treatment systems. I dont know the mechanisms used but it is used from what Ive heard. Water should give up its magnetic particles quite easily, I would think, since the metals are just floating about like flotsam and jetsam in the ocean.

@Charred - Those are two very good points, and I am sure that they are accounted for. The uses described in the article suggest scenarios where the metals are rather loosely fitting, so I think the cleanup job would be thorough. What I wonder about is if this process can be adapted to water treatment? Since magnetic separation systems can be used to sift through fluids, could they purify water as well? That seems to be an obvious application. Where I live the tap water has a lot of metals and so we generally dont drink it. I already have three metal fillings; I dont need more metal in my body.

What I wonder about is if this process can be adapted to water treatment? Since magnetic separation systems can be used to sift through fluids, could they purify water as well? That seems to be an obvious application. Where I live the tap water has a lot of metals and so we generally dont drink it. I already have three metal fillings; I dont need more metal in my body.

What I wonder about is if this process can be adapted to water treatment? Since magnetic separation systems can be used to sift through fluids, could they purify water as well? That seems to be an obvious application. Where I live the tap water has a lot of metals and so we generally dont drink it. I already have three metal fillings; I dont need more metal in my body.

That seems to be an obvious application. Where I live the tap water has a lot of metals and so we generally dont drink it. I already have three metal fillings; I dont need more metal in my body.

I see two things here that are necessary for magnetic separation to work well. First, the metals must be easily dislodged from whatever material or goop they happen to be sitting in. Otherwise, theyll just remain stuck, and the separation will be less than effective in pulling out all the metals. Second, the magnetic drum separator itself must be sufficiently strong. I think thats obvious, and the second point is related to the first. If the separating device is not strong it wont dislodge the metals; but there may be situations where the device is strong, but the metals are just stuck and wont budge.

Second, the magnetic drum separator itself must be sufficiently strong. I think thats obvious, and the second point is related to the first. If the separating device is not strong it wont dislodge the metals; but there may be situations where the device is strong, but the metals are just stuck and wont budge.

Second, the magnetic drum separator itself must be sufficiently strong. I think thats obvious, and the second point is related to the first. If the separating device is not strong it wont dislodge the metals; but there may be situations where the device is strong, but the metals are just stuck and wont budge.

amine functionalized magnetic nanoparticles for removal of oil droplets from produced water and accelerated magnetic separation | springerlink

amine functionalized magnetic nanoparticles for removal of oil droplets from produced water and accelerated magnetic separation | springerlink

Magnetic nanoparticles (MNPs) with surface coatings designed for water treatment, in particular for targeted removal of contaminants from produced water in oil fields, have drawn considerable attention due to their environmental merit. The goal of this study was to develop an efficient method of removing very stable, micron-scale oil droplets dispersed in oilfield produced water. We synthesized MNPs in the laboratory with a prescribed surface coating. The MNPs were superparamagnetic magnetite, and the hydrodynamic size of amine functionalized MNPs ranges from 21 to 255nm with an average size of 66nm. The initial oil content of 0.25wt.% was reduced by as much as 99.9% in separated water. The electrostatic attraction between negatively charged oil-in-water emulsions and positively charged MNPs controls, the attachment of MNPs to the droplet surface, and the subsequent aggregation of the electrically neutral oil droplets with attached MNPs (MNPs-oils) play a critical role in accelerated and efficient magnetic separation. The total magnetic separation time was dramatically reduced to as short as 1s after MNPs, and oil droplets were mixed, in contrast with the case of free, individual MNPs with which separation took about 3672h, depending on the MNP concentrations. Model calculations of magnetic separation velocity, accounting for the MNP magnetization and viscous drag, show that the total magnetic separation time will be approximately 5min or less, when the size of the MNPs-oils is greater than 360nm, which can be used as an optimum operating condition.

Amanullah M, Ramasamy J (2014) Nanotechnology can overcome the critical issues of extremely challenging drilling and production environments (SPE 171693). Paper presented at the Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, UAE, 1013 November

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This study was funded by the Maersk Oil in Doha, Qatar, and the Nanoparticles for Subsurface Engineering Industrial Affiliates Program at the University of Texas at Austin (member companies: Baker-Hughes, Nissan Chemical, and Foundation CMG).

Ko, S., Kim, E.S., Park, S. et al. Amine functionalized magnetic nanoparticles for removal of oil droplets from produced water and accelerated magnetic separation. J Nanopart Res 19, 132 (2017). https://doi.org/10.1007/s11051-017-3826-6

water purification using magnetic assistance: a review - sciencedirect

water purification using magnetic assistance: a review - sciencedirect

Water is a major source for survival on this planet. Its conservation is therefore a priority. With the increase in demand, the supply needs to meet specific standards. Several purification techniques have been adopted to meet the standards. Magnetic separation is one purification technique that has been adapted from ore mining industries to anti-scale treatment of pipe lines to seeding magnetic flocculent. No reviews have come up in recent years on the water purification technique using magnetic assistance. The present article brings out a series of information on this water purification technique and explains different aspects of magnetism and magnetic materials for water purification.

magnetic water treatment

magnetic water treatment

Strong neodymium magnets are often used in Magnetic Water Treatment to prevent or reduce scale formation with hard water. Does this really work? Is it fact or myth? K&J reviews the available information and experiments a bit on this controversial subject.

Hard water has a high mineral content, usually consisting of mostly calcium and magnesium. In fact, the measure of water hardness is expressed in various units that express how much calcium carbonate is in a given volume of water. Units include ppm (parts per million), gpg (grains per gallon), or mg/L (milligrams per liter).

Hard water isnt necessarily bad for you, but it can pose problems with the plumbing in your home. It can form hard deposits of calcium called scale, affecting faucets, shower-heads, dishwashers, and heating elements of water heaters. This can reduce water flow, heating efficiency, and leave spots on dishes. It can also require more soap to get good suds.

Conventional water softeners work with an ion-exchange process, where the calcium and magnesium in the water are replaced by sodium. This technology is proven, works consistently and does make water softer. It does reduce scale in your plumbing. You can find water softeners at your local hardware or home improvement store.

This is one of those topics where a quick search on the Internet provides wildly varying results. There isn't much clear information about magnetic water treatment, and some sites say it doesn't work. There is a great deal of mis-information that seems to either make false claims or appear to be scientifically bogus, further complicating the search.

Magnetic Water Treatment directs water to pass through a strong magnetic field. By placing two strong neodymium magnets on either side of the incoming pipe, all the water passes through a strong, uniform magnetic field.

Magnetic water treatment does not remove any calcium from the water. Technically, it is still just as hard as before it passed through the magnets. It claims to change the structure of the deposits that form, making them tend to be less apt to stick to surfaces.

Perhaps the biggest reason is that the results are hard to measure. With conventional, salt-based water softening, its easy to measure the amount of calcium dissolved in the water. Simply measure the calcium content before and after the treatment. If youve got less calcium in there after treatment, you know its working!

We have read heard a lot of anecdotal evidence about how well magnetic water treatment works. Still, no amount of stories equate to scientific evidence. Some of us here at K&J Magnetics use magnets on our water source at home, some dont. Are there any scientific publications that can help?

If you search for magnetic water treatment, you will quickly find references to work by Klaus Kronenberg, and claims made in Experimental evidence for the effects of magnetic fields on moving water, published in IEEE Transactions on Magnetics in September 1985. Claims include:

Unfortunately, many who refer to his work also make some pretty wild claims, putting the reliability of these results into question. We haven't read his paper, but references online just list his opinion on the matter. Is there a more reputable source on the subject?

The Wikipedia article on Magnetic Water Treatment points to a paper by J.M.D. Coey and Stephen Cass. Magnetic water treatment appeared in the Journal of Magnetism and Magnetic Materials #209 back in 2000.

Professor J. M. D Coey edited an early, important text on rare-earth magnets, Rare-Earth Iron Permanent Magnets. More recently he authored Magnetism and Magnetic Materials, a graduate level textbook about magnetism. Thats a large percentage of the magnet textbooks we own!

They tested MWT by passing water through a magnetic field of 1000 Gauss (0.1 T). The samples were then heated in open beakers, forming scale when the water evaporated. The scale was inspected by X-ray diffraction (which can reveal what its made of) and an electron microscope (to view the structure).

The results confirm earlier claims that there are two different types of calcium deposits made: calcite and aragonite. They are both made of the same stuff (calcium), but form in different structures. The small beads of calcite tend to make hard scale that clings well to surfaces. Aragonite forms in longer shapes which are less prone to form hard scale, and keep moving along with the water. The electron microscope shots are pretty clear!

Did the magnetically treated water form less scale in this test? No, not really. We saw about the same amount of scale. Of course, we were heating open containers, allowing the water to evaporate. This isnt really comparable to whats going on inside a water heater. The interesting result is that the scale in the two samples did seem different in how well it stuck to the aluminum heater.

We ran our finger across the evaporated deposits and didnt get any calcium on our finger with the untreated water. One rub across the magnetically treated water yielded a bunch of white calcium stuck to our finger. Some of the deposited calcium did not stick to the heater quite as well as the untreated water deposits. Does this mean that some of the calcium was less sticky? Sure. Could this be indicative of a higher aragonite percentage? Maybe.

We would like to see a test rig that might simulate a water heater. Run two systems, one with and one without magnetic water treatment. Its a long-term test, but the results would surely be interesting.

The test setup we used had a field strength of just over 3,000 gauss in the water pipe. The paper we referred to said that only a 1,000 gauss field was used. What strength is required? Were not sure, but here is a list of a few suggested sizes arranged by the size of common US pipes.

In each case, a pair of magnets is arranged on either side of the incoming water pipe. They are oriented so that they are attracting towards each other, which makes a strong, uniform field within the pipe. Some means of fastening the magnets is required to hold them in position, preventing them from falling off the pipe or slamming together.

mitsubishi heavy industries, ltd. global website | coagulation and magnetic-separation solution, hitachi ballast water purification system

mitsubishi heavy industries, ltd. global website | coagulation and magnetic-separation solution, hitachi ballast water purification system

Tokyo, Japan, March 12, 2010 --- Hitachi Plant Technologies, Ltd. (HQ: Tokyo; President & CEO: Masaharu Sumikawa) and Mitsubishi Heavy Industries, Ltd. (HQ: Tokyo; President: Hideaki Omiya), were granted on March 5, 2010, the first formal approval by the Japanese government for their jointly-developed Hitachi Ballast Water Purification System (ClearBallast).*1 Formal approval was based on the Procedure for Approval of Ballast Water Management Systems (G8), which is in accordance with the International Convention for the Control and Management of Ships' Ballast Water and Sediments adopted by the IMO*2 in February 2004. This became the first formal approval issued by the Japanese government.

To gain this formal approval, the companies performed land-based testing near Tokyo Bay using an actual-scale device and on-board testing using a test device installed on an LPG tanker (capacity: 78,500 m3, built at the Nagasaki Mitsubishi Heavy Industries shipyard) owned by Yuyo Steamship Co., Ltd. (HQ: Kanagawa; President & CEO: Masashi Yoshizawa). These tests were carried out in parallel and both met the IMO Performance Standard.*3 Additionally, on July 17, 2009, ClearBallast received final IMO approval in accordance with the Procedure for Approval of Ballast Water Management Systems that Make Use of Active Substances (G9). The company plans to aggressively market the system and has set orders for100 units as a sales target for fiscal 2012. Notes: *1. ClearBallast: Registered trademark of Hitachi,Ltd.used by Hitachi Plant Technologies under license. *2. IMO: International Maritime Organization *3. Ballast water discharge standards:

Overview of Hitachi Ballast Water Purification System (ClearBallast) Used as ballast for stabilizing hull balance, ballast water usually contains plankton, bacteria, mud, and sand specific to the port from which it was drawn. Most ballast water is discharged in ports of nations different from where it was loaded. Consequently, foreign organisms are discharged along with the seawater, and the resulting impact on marine ecosystems has become an international issue. To combat this problem, in February 2004, the IMO Council adopted the International Convention for the Control and Management of Ships' Ballast Water and Sediments (Ballast Management Convention). The Convention requires that the IMO Performance Standards be applied in a stepwise manner to ships undertaking international voyages in line with the year of building and the ballast tank capacity, with all ships required to adopt the standard by 2017. In line with these requirements, there is now a need for ships to be fitted with ballast-water treatment systems. ClearBallast purifies ballast water by combining magnetic separation technology developed for high-speed water treatment during rainy periods and coagulation technology used to remove plankton and bacteria at many water treatment plants. In contrast to sterilization-type approaches, the coagulation method does not use chlorine, ozone, ultraviolet light, or other disinfectants, and therefore, the risk of residual chemicals causing secondary contamination is removed. ClearBallast also has a smaller footprint and offers high-speed treatment through the use of bacteria flocculation (aggregation of small particles), which enables the use of coarse filters compared with ordinary filtration machines. ClearBallast had to be optimized in line with advanced ship-design techniques to ensure that such a purification device could be installed on ships and could then operate as part of a fully integrated system. Focusing their collective expertise and experience, Hitachi Plant Technologies and Mitsubishi Heavy Industries conducted joint research in order to develop and commercialize ClearBallast, and were ultimately successful in realizing a device suitable for on-board use.

Features: (1) Enhanced biological, environmental, and maritime safety 1. Even organisms growing in an environment consisting only of water treated by this system show no signs of inhibited growth or deformities.(Confirmed through organism toxicity testing.*4 2. Requiring no use of disinfectants, the system poses no threat of secondary contamination from residual chemicals. 3. The system has no adverse effect on paint or other coatings within the ballast tank. (Confirmed through corrosion assessment testing.) The above benefits demonstrate how the new system can help to enhance biological, environmental, and maritime safety.Note: 4. Biological toxicity testing: Biological toxicity testing compliant with guidelines set by the OECD (Organization for Economic Co-operation and Development). Culture tests were conducted for marine species skeletonema (algae), apohyale barbicornis (invertebrate), and javanica (type of fish) using treated water.

(2) Reduced mud buildup inside ballast tanks Capable not only of eliminating plankton, bacteria and the like from sea water, the system can also remove sand, mud, and other suspended solids originating from the sea bed before they accumulate in the tank. In addition, it can prevent the buildup of mud consisting of dead organisms within the ballast tanks.

(3) Suppression of the breeding of bacteria and algae inside ballast tanks ClearBallast not only inhibits the propagation of bacteria within mud, but because it also removes the bio-essential element phosphorous that is suspended in seawater, the system is able to greatly suppress the proliferation of algae generated in large amounts by red tide or other causes is by chance mixed into the ballast tank.

(4) Full line-up including explosion-proof specifications Also being studied are special versions of the system with specifications to prevent explosion, making them highly suitable for use in oil tankers, liquefied gas tankers, container ships carrying hazardous cargo, chemical tankers, and the like. Hereafter plans are being made to apply for additional Japanese government approval for such a version.

(5) Efficient power usage At 21 kW for 200 m3/h or 112 kW for 1,600 m3/h of ballast water, the system's power consumption is relatively low, and as extra power-generation capacity may not necessarily be needed, the effect on the ship's electrical system can be minimized.

Operation Sequence (1) Treatment is done when the water is taken on. First, magnetic power and flocculation agents are added to seawater in a high/low-speed roiling tank, and the water is roiled to form magnetized floc measuring around 1mm consisting of plankton, bacteria, mud, and other material.(2) When then passed through a magnetic separator, the floc adheres to magnetic disks and is removed. Finally, the treated water is filtered in a filter separator, before being pumped into the ballast tanks.(3) The system is safe because the plankton and bacteria contained in the recovered floc are killedthrough heat treatment.

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