Modification of activated carbon of rice husk using HDTMA-Br (SMAC) surfactant as nitrite ion (NO₂⁻) adsorbent

Surfactant modified activated carbon (SMAC) is a product resulting from the modification of activated carbon with surfactants to increase the adsorption ability of activated carbon against ions in water. Carbonization using pyrolysis at 300°C, 350°C, and 400°C. Activation of carbon was carried out in two ways, the first activation using H₃PO₄ activator, followed by heating at 410°C for 1 hour. Second, activation using H₃PO₄ followed by radiation with microwaves. The resulting activated carbon was modified with HDTMA-Br to form SMAC, then SMAC was applied for adsorption of nitrite (NO₂ ⁻) ions. This study aimed to determine the optimum conditions for carbonization temperature, radiation time, radiation power, adsorption time of HDTMA-Br. The adsorption capacity of SMAC on nitrite ions and the adsorption process of HDTMA-Br were studied (thermodynamic data). Characterization was carried out using FTIR, SEM, and GSA. The optimum carbonization temperature was 300°C; the optimum activation was 5 minutes and 400 watts, the optimum time for HDTMA-Br adsorption was 4 hours with the adsorption capacity was 7.304 mg/g. SMAC is effective in adsorbing nitrite ions where the adsorption capacity was 0.741 mg/g, and the adsorption efficiency is 98.833%. The adsorption of HDTMA-Br on activated carbon was physical adsorption, SMAC has an N-(CH₃)₃ group from HDTMA-Br with a SMAC surface area of 24.173 m²/g. (paper)