Evaluation and Optimization of Azithromycin Removal by Raw and Alkali‐Modified Peanut Shells Using Taguchi‐Based Experimental Design Approach

ABSTRACT Advanced treatment methods for removing antibiotics are cost‐intensive. Subsequently, the goal of environmental and economic sustainability has switched attention towards bio‐adsorbents. This study evaluated the effectiveness of raw and alkali‐modified peanut shell powder as a cost‐effective, novel adsorbent for removing azithromycin, one of the most widely used drugs worldwide. Prepared adsorbents were characterized by FTIR and SEM equipped with EDX. Experiments designed using a Taguchi‐based approach were performed with a synthetic azithromycin solution to optimize initial concentrations, adsorbent dose, pH, and time. The results showed 63% removal with raw adsorbent at pH 11, an initial concentration of 20 mg/L, a time of 45 min, and an adsorbent dose of 0.4 g/L. With the modified adsorbent, an attractive 85% (maximum) removal was achieved at pH 11, an initial concentration of 30 mg/L, a time of 60 min, and an adsorbent dose of 0.4 g/L. Based on analysis of variance (ANOVA), pH and initial concentration are identified as the most influential factors for azithromycin removal. The improved adsorption performance of modified peanut shells (q max = 192.1 mg/g compared to 159.2 mg/g for raw PS) was due to increased surface heterogeneity, enhanced electrostatic interactions, and greater accessibility of oxygen‐containing functional groups, as confirmed by kinetic, isotherm, and surface analysis.