Iron-Modified Biochar from Sugarcane Straw to Remove Arsenic and Lead from Contaminated Water

The presence of arsenic (As) and lead (Pb) in water above tolerable levels is a global concern, as both elements are extremely toxic and can compromise the health of millions of people. In this study, we evaluated biochars pyrolyzed at 350 (BC350) and 750 °C (BC750) and then modified with ferric chloride (FeCl3) to remove As and Pb from water samples contaminated by mining activity. The use of FeCl3-modified biochar was an efficient strategy to remove As and Pb from water. Sorption on biochars followed the pseudo-second-order kinetics, represented by two sorption speeds, being higher at the beginning of the reaction and falling over time. The modification with FeCl3 increased the specific surface area, removed the dissolved organic carbon, and increased the capacity of BC350 to sorb Pb. These physical and chemical alterations of the biochar played a significant role in the sorption capacity and speed of As and Pb.