Studi Kinetika Adsorpsi terhadap Ion Nitrat (No3-) oleh Biochar Termodifikasi Kalsium dari Cangkang Telur

Abstract

This study aims to enhance the nitrate adsorption ability of biochar by producing protonated calcium-modified biochar (cationic biochar) and evaluate its adsorption kinetics. Corn cob biomass was impregnated with eggshell-derived CaCl₂ then pyrolyzed using slow pyrolysis for 4 hours at 280–400°C to produce calcium-modified biochar (B-Ca). Furthermore, B-Ca was protonated with oxalic acid to form protonated calcium-modified biochar. The physicochemical properties were characterized using FTIR analysis, moisture content, ash content, pH, and pHₚzc. FTIR results indicated the formation of Ca-O bonds. Moisture content, ash content, pH, and pHPZC decreased with increasing Ca ratio. Surface area and porosity also increased with increasing Ca ratio. PB-Ca224 was the optimal variant, exhibiting the highest adsorption capacity of 7,582 mg/g at an optimal time of 30 minutes compared to unmodified biochar (CB) only 4,434 mg/g. Kinetic analysis indicates that adsorption follows a pseudo-second-order model with a Qe value of 7.622 mg/g and an R² of 0.9999, suggesting the involvement of electrostatic interactions or chemical interactions.