Heavy metal ion removal

Electrochemical wastewater treatment — may involve (a) -> electrolysis with the purpose of heavy metal ion removal, (b) electrochemical transformation of anions, e.g., perchlorate, nitrate, (c) oxidation of organic pollutants, (d) - electrodialysis, or (e) - capacitive deionization. 

RorrerG. L, 1999. Heavy-metal ions, removal from wastewater. In Meyers R. A. (Ed.), Encyclopedia of Environmental Pollution and Cleanup, John Wiley, NY, 771-779... 

Application in Heavy Metal Ion Removal from Aqueous Effluents... 

X. Liu, Q. Hu, Z. Fang, X. Zhang, and B. Zhang, Magnetic chitosan nanocomposites A useful recyclable tool for heavy metal ion removal, Langmuir, 25 (2009) 3-8. 

Cao, C.Y., Cui, Z.M., Chen, C.Q., Song, W.G., Cai, W., 2010. Ceria hollow nanospheres produced by a template-free microwave-assisted hydrothermal method for heavy metal ion removal and catalysis. J. Phys. Chem. C 114 (2010), 9865—9870. 

D. Hagars, Performance Evaluation for Heavy Metal Ion Removal Using Silica Polyamine Composites Made with Different Silica Gels and Polyamines, Masters thesis. University of Montana, 1999. 

Kampalanonwat P, Supaphol P (2010) Preparation and adsorption behavior of aminated electrospun polyacrylonitrile nanofiber mats for heavy metal Ion removal. Acs Appl Mater Inter 2 3619-3627... 

Jha et al. [21] have studied the process of zeolite formation from coal fly ash and heavy metal ion removal characteristics of zeolite X in multi-metal system. These authors have reported that the active carbon present in the fly ash can enhance the formation of zeolite Na-X. It has been opined that zeolite, Na-A can be initially crystallized by employing hydrothermal activation of fused coal fly ash (CFA), which can later get transformed to zeolite Na-X corresponding to the increase of NaOH concentration and/or reaction time. It has been confirmed that the synthe-... 

Most of the heavy-metal impurities present in 2inc salt solutions must be removed before the precipitation reaction, or these form insoluble colored sulfides that reduce the whiteness of the 2inc sulfide pigment. This end is usually achieved by the addition of 2inc metal which reduces most heavy-metal ions to their metallic form. The brightness of 2inc sulfide can be improved by the addition of a small amount of cobalt salts (ca 0.04% on a Co/Zn basis) (20). Barium sulfate [7727-43-7] formed in the first step is isolated and can be used as an extender. 

The chlorination of toluene in the absence of catalysts that promote nuclear substitution occurs preferentially in the side chain. The reaction is promoted by free-radical initiators such as ultraviolet light or peroxides. Chlorination takes place in a stepwise manner and can be controlled to give good yields of the intermediate chlorination products. Small amounts of sequestering agents are sometimes used to remove trace amounts of heavy-metal ions that cause ring chlorination. 

Calcium ion enters the system not ordy in the form of water hardness but also in the form of calcium salts contained in the sod. Other heavy-metal ions such as aluminum and ferric iron may also be present in the sod, and must be removed by an appropriate budder to achieve good sod removal. Effective budders for cotton washing are those for which the calcium dissociation constant, expressed as or —logif -, is >4 and preferably >7 (33). 

Polyelectrolytes such as the ion exchange plastics form an interesting group of materials because of their ability to interact with water solutions. They have been used in medical applications involving the removal of heavy metal ions from the human body. They can be used to interact with external electric fields and change their physical properties drastically as is illustrated by the fact that some electrically active liquid crystals are polyelectrolytes of low molecular weight. 

Sometimes we have to precipitate one ion of a sparingly soluble salt. For example, heavy metal ions such as lead and mercury can be removed from municipal waste-water by precipitating them as the hydroxides. However, because the ions are in dynamic equilibrium with the solid salt, some heavy metal ions remain in solution. How can we remove more of the ions ... 

Mehta SK, Gaur JP (2005) Use of algae for removing heavy metal ions from wastewater progress and prospects. Grit Rev Biotechnol 25 113... 

As illustrated in Example, wastewater resulting from metal processing often contains significant amounts of toxic heavy metal ions that must be removed before the water can be returned to the environment. One method uses sodium hydroxide solution to precipitate insoluble metal hydroxides. Suppose that... 

C18-0115. One way to remove heavy metal ions from water is by treatment with sodium carbonate. Calculate the mass of the precipitate that will form and the concentration of remaining in solution after 0.750... 

Chemical precipitation is used in porcelain enameling to precipitate dissolved metals and phosphates. Chemical precipitation can be utilized to permit removal of metal ions such as iron, lead, tin, copper, zinc, cadmium, aluminum, mercury, manganese, cobalt, antimony, arsenic, beryllium, molybdenum, and trivalent chromium. Removal efficiency can approach 100% for the reduction of heavy metal ions. Porcelain enameling plants commonly use lime, caustic, and carbonate for chemical precipitation and pH adjustment. Coagulants used in the industry include alum, ferric chloride, ferric sulfate, and polymers.10-12... 

Spirodela intermedia, L. minor, and P. stratiotes were able to remove Pb(II), Cd(II), Ni(II), Cu(II), and Zn(II), although the two former ions were removed more efficiently. Data fitted the Langmuir model only for Ni and Cd, but the Freundlich isotherm for all metals tested. The adsorption capacity values (K ) showed that Pb was the metal more efficiently removed from water solution (166.49 and 447.95 mg/g for S. intermedia and L. minor, respectively). The adsorption process for the three species studied followed first-order kinetics. The mechanism involved in biosorption resulted in an ion-exchange process between monovalent metals as counterions present in the macrophytes biomass and heavy metal ions and protons taken up from water.112... 

Ngah, W.S.W. and Hanafiah, M.A.K.M., Removal of heavy metal ions from wastewater by chemically modified plant wastes as adsorbents A review, Bioresource Technology, 99, 3935-3948, 2008. 

Metal salicylates are occasionally incorporated into mixtures of unknowns for qualitative inorganic analysis. During the conventional group separation, organic radicals are removed by evaporation with nitric acid. When salicylates are present, this can lead to formation of trinitrophenol through nitration and decarboxylation. This may react with any heavy metal ions present to form unstable or explosive picrates, if the evaporation is taken to dryness. The MAQA alternative scheme of analysis obviates this danger. 

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