Removal of vanadium and chromium from vanadium wastewaters with amino-functionalized γ-AlOOH

Chitosan-modified boehmite (AF-gamma-AlOOH) was synthesized, characterized and used as adsorbent for removing vanadium and chromium from vanadium industrial wastewaters. Batch V(V) adsorption data showed that AF gamma-AlOOH possessed a V(V) adsorption capacity of 217 mg/g. The adsorption behavior followed the Langmuir isotherm model and pseudo second-order kinetics. The adsorption process was spontaneous and endothermic. Continuous fixed-bed column adsorption measurements showed that V(V) and Cr(VI) could be simultaneously decreased to less than the national emission standards (0.5 mg/L). The adsorbed AF-gamma-AlOOH could be recycled by separating V(V) and Cr(VI). The XPS results indicated that the V(V) and Cr(VI) first interacted with functional groups such as -OH and -NH2 of AF-gamma-AlOOH, and then was partially reduced to V(IV) and Cr(III), respectively. A whole process was proposed to realize separation and recovery of V(V) and Cr(VI) from the vanadium industrial wastewaters.