Removal of diclofenac, ciprofloxacin and sulfamethoxazole from wastewater using granular activated carbon from hazelnut shell: isotherm, kinetic and thermodynamic studies

The purpose of this study is to determine the effectiveness of phosphoric acid activated hazelnut shell carbon (HSAC) in removing diclofenac (DC), ciprofloxacin (CIP) and sulfamethoxazole (SMX) from aqueous solutions and wastewater. Scanning electron microscopy studies showed that HSAC surface contains numerous irregular pits of various sizes and shapes. The Brunauer-Emmett- Teller surface area of HSAC was found to be 1,173 m2 center dot g-1. The effect of several parameters includ-ing pH, contact time, initial concentration, dosage and temperature on the batch adsorption of DC, CIP and SMX were investigated. Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms were used to model the adsorption equilibrium of DC, CIP and SMX. The Langmuir isotherm was found to be compatible with the adsorption of DC, CIP and SMX onto HSAC, with maximum adsorption capacities of 125, 95.2 and 285.7 mg center dot g-1 for DC, CIP and SMX, respectively. The pseudo-second-order model was determined to be the most appropriate kinetic model for the adsorption of DC, CIP and SMX. Thermodynamic studies revealed that the adsorption of DC, CIP and SMX onto HSAC was spontaneous and endothermic. The results indicated that HSAC was an easily available, ecofriendly and effective adsorbent for the removal of DC, CIP and SMX from wastewater.