Remediation of arsenic-contaminated paddy soil by iron-modified biochar

• Published in: Environmental science and pollution research international 2018-07, Vol.25 (21), p.20792-20801
• Main Authors: Wu, Chuan, Cui, MengQian, Xue, ShengGuo, Li, WaiChin, Huang, Liu, Jiang, XingXing, Qian, ZiYan
• Format: Article
• Language: English
• Subjects: Aquatic Pollution; Arsenic; Arsenic - chemistry; Atmospheric Protection/Air Quality Control/Air Pollution; Charcoal; Charcoal - chemistry; Earth and Environmental Science; Ecotoxicology; Electron microscopes; Environment; Environmental Chemistry; Environmental Health; Environmental Pollution - analysis; Environmental Restoration and Remediation - methods; Environmental science; Ferric chloride; Food contamination; Food security; Immobilization; Iron; Iron - chemistry; Iron chlorides; Organic Chemicals; Oxides - chemistry; pH effects; Remediation; Research Article; Scanning electron microscopy; Sodium bicarbonate; Soil - chemistry; Soil contamination; Soil investigations; Soil pH; Soil Pollutants - chemistry; Soil pollution; Soil remediation; Sulfates; Waste Water Technology; Water Management; Water Pollution Control; X-ray diffraction
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-018-2268-8

Arsenic contamination in paddy soils has aroused global concern due to its threats to food security and human health. Biochar modified with different iron materials was prepared for arsenic (As) immobilization in contaminated soils. Soil incubation experiments were carried to investigate the effects of biochar modified with Fe-oxyhydroxy sulfate (Biochar-FeOS), FeCl 3 (Biochar-FeCl 3 ), and zero-valent iron (Biochar-Fe) on the pH, NaHCO 3 -extractable As concentrations, and the As fractions in soils. The scanning electron microscope and X-ray diffraction analysis demonstrated that iron was successfully loaded onto the surface or embedded into the pores of the biochar. Addition of Biochar-FeOS, Biochar-FeCl 3 , and Biochar-Fe had no significant effects on the soil pH but significantly decreased the contents of NaHCO 3 -extractable As in soils by 13.95–30.35%, 10.97–28.39%, and 17.98–35.18%, respectively. Biochar-FeOS, Biochar-FeCl 3 , and Biochar-Fe treatments decreased the concentrations of non-specifically sorbed and specifically sorbed As fractions in soils, and increased the amorphous and poorly crystalline, hydrated Fe, Al oxide-bound, and residual As fractions. Compared with the other iron-modified biochars, Biochar-FeOS showed the most effective immobilization and has the potential for the remediation of As-contaminated paddy soils.