SYNTHESIS OF SAGO-BARK BASED ACTIVATED CARBON VIA MICROWAVE ACTIVATION FOR AMOXICILLIN REMOVAL: OPTIMIZATION VIA RESPONSE SURFACE METHODOLOGY

Abstract

Antibiotics such as amoxicillin (AMOX), when introduced into water bodies due to inadequate wastewater treatment, can pose serious environmental risks, affecting aquatic life. This concern led to the present study aimed at synthesizing sago bark-based activated carbon (SBAC) for the adsorption of AMOX from water. SBAC was prepared using a combined physicochemical activation process, which involved chemical activation with potassium hydroxide (KOH) and subsequent microwave-assisted physical activation using carbon dioxide (CO₂) gas. The optimization of SBAC synthesis was realized harnessing response surface methodology (RSM) with a central composite design (CCD). The optimal conditions identified were 556.41 watts for radiation power, 6.06 minutes for activation time, and a KOH impregnation ratio (IR) of 1.76 g/g. Under these conditions, AMOX uptake and SBAC yield were optimized at 75.65 mg/g and 31.54 %, respectively. The models accurately predicted actual values of 77.59 mg/g for AMOX uptake and 32.56 % for SBAC yield, with low errors of 2.50 % and 3.13 %, confirming the models' reliability. The uptake of AMOX was primarily swayed by radiation power, followed by IR, while the yield of SBAC was mostly governed by radiation power, succeeded by activation time. Scanning electron microscopy (SEM) analysis revealed that the raw sago bark had a non-porous structure, whereas the activation process created a highly porous SBAC surface, demonstrating the effectiveness of the activation methods. Isotherm analysis indicated that AMOX adsorption onto SBAC followed the Freundlich model, achieved an adsorption capacity (Q_m) of 110.52 mg/g, suggesting multilayer adsorption on a heterogeneous surface. Overall, the findings highlight that SBAC is an efficient, low-cost, and sustainable adsorbent for mitigating antibiotic pollution in aquatic environments.