One-step phosphoric acid activation of pomegranate peel powder for effective tetracycline removal from aqueous solution

Pristine biochar (PBC) and phosphoric acid-activated biochar (PAC) derived from pomegranate peel powder were produced and evaluated for the adsorption of tetracycline (TC) from aqueous solution. Physicochemical characterization using BET, FESEM and FTIR complements the development of microporous network alongside mesoporous architecture in PAC and the presence of functional groups for TC interaction. PAC exhibited high specific surface area of 1882 m 2 /g compared to PBC with specific surface area of 195 m 2 /g. Batch adsorption experiments were performed at pH 4, initial TC solution concentration of 10–150 mg/L, adsorbent dosage of 5–15 mg, contact time of 300 min and temperature range between 298 and 318 K. The adsorption kinetics was found to follow pseudo second-order model, while the Langmuir model provided the best correlation with maximum adsorption capacities of 436 mg/g and 596 mg/g at 25 °C and 45 °C, respectively. Regeneration studies shows that PAC biohar mainitained TC removal efficiency > 89% over five cycles of adsorption-desorption test. The results demonstrate the efficacy of phosphoric acid-activated pomegranate peel carbon as a sustainable adsorbent for removing pharmaceutical contaminants from water.