입상활성탄을 이용한 인공 조제 지하수내의 Cr(Ⅵ) 제거와 그 활성탄의 재생 = Cr(VI)Removal from Artificial Groundwater by Granular Activated Carbon and Regeneration of the Spent Carbon

다국어 초록 (Multilingual Abstract)

Removal of hexavalent chromium from artificial groundwater (AGW) by grnaular activated carbon (GAC) was investigated in batch and continuous flow column studies. Experimental parameters that were examined included solution pH, presence of dissolved oxygen (DO). and GAC pretreatment with Fe(Ⅱ). As the solution pH increased from 4 to 7.5, the amount of Cr(VI) removed by both GACs decreased significantly. Exclusion of DO from the experimental systems resulted in greater removal of Cr(VI) from solution, possibly as a result of reduction to Cr(Ⅲ). However, pretreatment of the GAC with a reductant Fe(Ⅱ) did not improve Cr(VI) removal. Equilibration with 0.01M K_2HPO_4 [to extract adsorbed Cr(VI)] followed by a wash with 0.02N H_2SO_4 [to remove precipitated/sorbed Cr(Ⅲ)] proved to be a viable approach for the regeneration of carbons whose Cr(VI) removal capacities had been exhausted. The performance of the regenerated carbons exceeded that of the virgin carbons. primarily because of the favorable adsorption of Cr(VI) at lower pH values and the reduction of Cr(VI) to Cr(Ⅲ). The presence of Cr(Ⅲ) in acid wash solutions provides direct evidence that Cr(VI) is reduced to Cr(Ⅲ) in GAC systems under relatively acidic conditions. GAC performance over five complete cycles was consistently high, which suggests that such a system will be able to function over many operation cycles without deleterious effects.