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Of the variety of adsorbents available for the removal of heavy and toxic metals, activated carbon has been the most popular. A number of minerals, clays and waste materials have been regularly used for the removal of metallic pollutants from water and industrial effluents. Recently there has been emphasis on the application of nanoparticles and nanostructured materials as efficient and viable alternatives to activated carbon. Carbon nanotubes also have been proved effective alternatives for the removal of metallic pollutants from aqueous solutions. Because of their importance from an environmental viewpoint, special emphasis has been given to the removal of the metals Cr, Cd, Hg, Zn, As, and Cu. Separation of the used nanoparticles from aqueous solutions and the health aspects of the separated nanoparticles have also been discussed. A significant number of the latest articles have been critically scanned for the present review to give a vivid picture of these exotic materials for water remediation.

This paper presents the results of the electro-oxidation of pollutants in synthetic textile wastewater containing partially soluble disperse dyes. The experiments were performed in an electrochemical undivided cell reactor using seven different anode materials and 0.1 M NaCl as the supporting electrolyte. With the Ti/Pt-Ir anode, which showed the best performance among all the tested materials, additional experiments were also carried out using 0.05 M Na 2 SO 4 as the supporting electrolyte. Experimental results obtained in the electrochemical reactor, supported by the data obtained during cyclic voltammetry studies, showed that under the conditions of the present research the removal of pollutants was mediated by active chlorine generated by electro-oxidation of chloride ions or by other mediators generated in situ and not by a direct discharge of pollutants at the anode. Under the conditions of free pH evolution 39% removal of chemical oxygen demand was obtained after 40 min of electrolysis. The apparent pseudo-first-order rate constant for the removal of color was equal to 2.54 × 10 -4 s -1 and it increased to 8.23 × 10 -4 s -1 under pH control at the value of 4.5, resulting in 90% removal of color after the passage of 1.9 A h dm -3 . In comparative studies on the chemical oxidation of pollutants by hypochlorite far lower efficiency was obtained.

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