H3PO4-modified biochar derived from jacaranda fruits for phenol removal: Preparation, adsorption kinetics, isotherms, and thermodynamics

Abstract

Phenolic compounds are hazardous pollutants that threaten aquatic ecosystems and human health, necessitating effective removal from industrial effluents. This study evaluates phenol adsorption using raw Jacaranda biomass (BJ) and phosphoric acid-activated biochar (H-BJ). Activation at 600 °C produced a highly porous adsorbent with a Brunauer–Emmett–Teller (BET) surface area of 791 m2/g and enriched surface functionalities, as confirmed by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, X-ray diffraction analysis, pH point of zero charge (pHpzc), and BET analyses. FTIR indicated the formation of additional hydroxyl groups that enhanced phenol interaction. Adsorption behavior followed Langmuir and Freundlich isotherms and pseudo-second-order kinetics, indicating uniform and predominantly physical adsorption. Maximum capacities reached 40.127 mg/g for BJ and 61.732 mg/g for H-BJ at 600 °C. Thermodynamic parameters confirmed a spontaneous, exothermic process with increased entropy. Application of H-BJ600 (2% dosage) to olive mill wastewater achieved 74% phenolic removal with a qe of 45.42 g/g. These findings demonstrate the potential of Jacaranda-derived activated biochar as an efficient adsorbent for phenol remediation and wastewater treatment.