Modifikasi Magnetik Fe3O4 pada Biochar dari Tongkol Jagung dan Studi Adsorpsinya terhadap Fosfat

Abstract

Biochar has the potential to be used as an adsorbent to reduce phosphate levels in water. However, based on the functional groups on its surface, biochar still has a lot of negative charges, making it less effective in adsorbing anions. Therefore, modification is needed to increase phosphate adsorption. This study aims to increase the adsorption capacity for phosphate through modification by using magnetic material, Fe₃O₄. Biochar was produced through pyrolysis at a temperature of 200–450°C for 4 hours, resulting in biochar with a yield of 33.728% and a water content of 3.922%. After pyrolysis, the biochar was oxidized using a 15% H₂O₂ solution to increase the polar functional groups on its surface. The oxidized biochar was then modified with varying masses of Fe₃O₄ (1:0.5; 1:0.75; and 1:1). Characterization was performed through FTIR analysis, moisture content, ash content, and iodine number. FTIR results showed that modification with the addition of Fe₃O₄ to biochar introduced a new functional group, namely Fe-O at ~538–546 cm⁻¹. Modification with Fe₃O₄ increased the adsorption capacity, with a maximum capacity of 18.077 mg/g at a ratio of 1:1 and an efficiency of 72% at a phosphate concentration of 50 ppm. The adsorption isotherm model followed the Freundlich model, with the highest coefficient of determination (R²) value of 0.9871, indicating that the adsorption process occurred in a multilayer manner