Removal of Lead and Arsenic from Contaminated Water Using a Sugarcane Bagasse Biochar–Metal Organic Framework (BC-MOF) Adsorbent

The presence of highly toxic metals in aquatic environments is a major environmental concern, affecting both ecosystems and human health. Conventional removal methods are often limited by high costs, low efficiency, and the generation of secondary waste. Biochar produced by the pyrolysis of sugarcane bagasse under oxygen-limited conditions is a sustainable alternative owing to its porous structure, which can retain metal contaminants. In this study, a biochar obtained at 400 °C (BC400) was combined with cobalt ferrite (CoFe2O4) and terephthalic acid to produce a biochar–metal organic framework composite (BC-MOF). The composite was evaluated for the removal of lead (Pb) and arsenic (As) from aqueous solutions (nominal concentration of 2 mg L-1) at initial pH values of 4.5, 6.0, 7.0, and 8.5, using 0.25 g of adsorbent in 250 mL of solution (1 g L-1). Samples were collected at eight contact times between 15 min and 24 h and analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES). Pb was removed to concentrations reported as zero within 8 h at pH 4.5 and 8.5 and within 24 h at pH 6.0, and the residual concentration at pH 7.0 after 24 h was 0.034 mg L-1. As removal was gradual and incomplete within 24 h, with the best performance at pH 4.5 (residual concentration of 0.696 mg L-1). The composite also showed a marked buffering effect, raising the pH of acidic solutions to near neutrality. These results indicate that BC-MOF is a promising lowcost material for the remediation of water contaminated with Pb and As.