摘要
Chromium compounds are widely used in electroplating, metal finishing, magnetic tapes, pigments, leather tanning, wood protection and electronic and electrical equipment. Hexavalent chromium is a highly toxic metal and produces health damages. The most soluble, mobile and toxic forms of hexavalent chromium in soils are chromate and dichromate and the chromium distribution is also controlled by redox processes, its adsorption decreases with increasing pH and when competing dissolved anions are present. Several techniques have been developed to remove Cr(VI) from wastewater but these techniques have disadvantages such as high cost, non-selective, pH dependence, etc. The use of low cost sorbents has been investigated as a replacement for current costly methods;natural materials with a high adsorption capacity for heavy metals can be obtained. Modification of the sorbents can improve adsorption capacity. This paper includes some techniques for remove Cr(VI) with clays, silica and zeolites from aqueous solutions, some of the treated adsorbents show good adsorption capacities.
Chromium compounds are widely used in electroplating, metal finishing, magnetic tapes, pigments, leather tanning, wood protection and electronic and electrical equipment. Hexavalent chromium is a highly toxic metal and produces health damages. The most soluble, mobile and toxic forms of hexavalent chromium in soils are chromate and dichromate and the chromium distribution is also controlled by redox processes, its adsorption decreases with increasing pH and when competing dissolved anions are present. Several techniques have been developed to remove Cr(VI) from wastewater but these techniques have disadvantages such as high cost, non-selective, pH dependence, etc. The use of low cost sorbents has been investigated as a replacement for current costly methods;natural materials with a high adsorption capacity for heavy metals can be obtained. Modification of the sorbents can improve adsorption capacity. This paper includes some techniques for remove Cr(VI) with clays, silica and zeolites from aqueous solutions, some of the treated adsorbents show good adsorption capacities.
