Removal of hexavalent chromium from groundwater by granular activated carbon

Journal Article · Tue Feb 01 04:00:00 EST 2000 · Water Environment Research

DOI:https://doi.org/10.2175/106143000X137086· OSTI ID:20014585

Han, I; Schlautman, M A; Batchelor, B

Removal of hexavalent chromium, Cr(VI), from an artificial groundwater by two commercially available granular activated carbons (GACs) was investigated in batch and continuous-flow column studies. Experimental parameters examined included solution pH, presence of dissolved oxygen (DO), and GAC pretreatment with reducing agents. As solution pH increased from 4 to 7.5, the amount of Cr(VI) removed by both GACs decreased significantly. Removal of DO from experimental systems enhanced GAC performance, but pretreatment of the GACs with reductants (ferrous iron or dithionite) did not improve Cr(VI) removal. Equilibration with 0.01 M dibasic potassium phosphate [to extract adsorbed Cr(VI)] followed by a wash with 0.02 N sulfuric acid [to remove precipitated-sorbed Cr(III)] proved to be a viable method to regenerate carbons whose Cr(VI) removal capacities were exhausted. Performance of regenerated carbons exceeded that of virgin carbons, primarily because of the favorable adsorption of Cr(VI) at low pH values and the reduction of Cr(VI) to Cr(III) on acidic GAC surfaces. 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. Granular activated carbon performance during five complete cycles was consistently high, which suggests that such a system will be able to function over many operation cycles without deleterious effects.

• Research Organization: Texas A and M Univ., College Station, TX (US)
• Sponsoring Organization: US Department of Energy
• DOE Contract Number: FC04-95AL85832
• OSTI ID: 20014585
• Journal Information: Water Environment Research, Journal Name: Water Environment Research Journal Issue: 1 Vol. 72; ISSN 1061-4303; ISSN WAERED
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ACTIVATED CARBON
CHROMIUM
GROUND WATER
PERFORMANCE
PH VALUE
REMEDIAL ACTION