Abstract:Cr(Ⅵ) was adsorbed by quaternary ammonium lignin prepared from straw. The mechanism of adsorption was revealed by FTIR and XPS analysis of quaternary ammonium lignin before and after adsorption. Effects of initial concentration of Cr(Ⅵ), temperature, time and initial pH value on adsorption were investigated. The results show that Cr(Ⅵ) is adsorbed mainly by quaternary ammonium and amino in the form of HCrO4-. Part of adsorbed HCrO4- is reduced to Cr(Ⅲ) by alkyl groups and phenolic hydroxyl groups on the benzene ring and absorbed latter by carboxyl groups. A small amount of Cr(Ⅵ) is directly reduced to Cr(Ⅲ) by electron donating functional groups. When initial concentration of Cr(Ⅵ) is 50 mg/L, initial pH value is 1.08, adsorption time is 120 min and temperature is 25 ℃, the removal rate of Cr(Ⅵ) is 99.76%. The adsorption follows the quasi-second-order kinetics and Langmuir models, which indicates that the adsorption is monolayer homogeneous chemisorptions. The research on mechanism and behavior of Cr(Ⅵ) adsorption by quaternary ammonium lignin can provide theoretical basis for resource utilization of rice and removal of chromium.