Chitosan-modified iron fillings materials for remediation of arsenic-contaminated soil

Arsenic (As) contamination of soils adversely affects human health and ecosystems and is an environmental issue of serious concern worldwide. Efficient and economical remediation methods are urgently needed. In this research, a chitosan-modified scrap iron filings (CFF) composite was prepared by using industrial scrap iron filings and chitosan to stabilize As-contaminated soil. The optimal modification conditions were explored, and CFF was applied to As-contaminated soil to investigate its remediation effect and stabilization mechanism. The results showed that the optimal preparation conditions of CFF were chitosan concentration of 3.75 % (w/w), chitosan to scrap iron filings ratio of 1:1, optimal modification temperature of 40 degrees C, iron filings particle size of 35 - 80 mesh, and 10 % glutaraldehyde crosslinking for 6 h, and the stabilization efficiency of As was 73.98 %. The adsorption behavior of CFF was consistent with the pseudo -second -order kinetic model and the Langmuir isotherm model, and the best adsorption effect was achieved at pH = 5 - 6. The possible mechanisms of As stabilization by CFF were surface complexation, hydrogen bonding synergy, precipitation, electrostatic attraction, and van der Waals forces.