Preparation of sulfonated coal@ZVI@chitosan-acrylic acid composite and study of its removal of groundwater Cr(VI)

Abstract The effects of Cr(VI) pollution in groundwater run wide and deep. Without effective remediation, Cr(VI) harms the environment and human health. With in situ treatment methods in which permeable reactive walls serve as the main body, chitosan-acrylic acid sols (CS-AA) were used to stabilize zero-valent iron (ZVI), and acid-modified sulfonated coal (SC) was used as the carrier to prepare SC@ZVI@CS-AA. The interaction between SC@ZVI@CS-AA and Cr(VI) conformed to a pseudo second-order kinetic model suggesting chemisorption. The Langmuir model provided a good fit to the data for adsorption of Cr(VI) by SC@ZVI@CS-AA. SC@ZVI@CS-AA was characterized using XRD, FTIR, SEM and TG − DSC analyses. The effects of contact time, initial Cr(VI) concentration, temperature, material ratios, pH, dosage of SC@ZVI@CS-AA and interfering ions on the adsorption of Cr(VI) were investigated. Under the optimal conditions, the efficiency for removal of Cr(VI) reached 98.5%. The adsorption of Cr(VI) was significantly inhibited by SO42-. In addition, the capacity for adsorption of Cr(VI) by SC@ZVI@CS-AA remained above 70% after three use cycles. Overall, SC@ZVI@CS-AA proved to be a promising and environmentally friendly medium for removal of Cr(VI) from groundwater.