Biochar as a potential material for removal of arsenic from water

Biochar is considered to be a low-cost, eco-friendly and sustainable material for various environmental implications, including water treatment. Here, we evaluated arsenic (As) removal efficiency of various biochars produced at 300, 500, and 700°C in aqueous solutions and drinking water. Both arsenite (As(III)) and arsenate (As(V)) species were successfully removed from aqueous solutions, with slightly higher sorption affinity, Q_L, for As(V) than As(III). The As removal spanned 81% to 99% for different biochars, with the maximum sorption obtained for perilla leaf biochar at pH 7 and 6. Surface functional moieties contributed to As sequestration by the biochars examined here. Arsenic K-edge XANES spectroscopy demonstrated oxidation of As(III) to As(V) which could be an additional benefit of biochar in sorption process and As purification. The study highlights some important aspects of As-biochar interactions before its application in treatment of and As-contaminated drinking well water.