Removal of ciprofloxacin from aqueous solutions by pumpkin peel biochar prepared using phosphoric acid

Abstract

In this study, novel biochar was fabricated from pumpkin peels with phosphoric acid activation (PPBPA) and characterized by ultimate and proximate analysis, BET surface area determination, SEM, FT-IR spectroscopy and pH(PZC) assay. The PPBPA demonstrated quite a high surface area, microporous structure and low ash content with values of 689.9 m(2)/g, 6.0 angstrom, and 6.4%, respectively. The PPBPA was examined for the batch removal of ciprofloxacin from aqueous solutions by investigating parameters such as pH, contact time, PPBPA dosage and initial ciprofloxacin (CPX) concentration. The removal of CPX was maximum at a pH of 8.0 and reached equilibrium at 24 h. The CPX adsorption onto PPBPA showed high agreement with the pseudo-second-order kinetic model. The percent removal of CPX decreased with the increasing initial concentration of CPX. The CPX adsorption equilibrium data onto PPBPA were found to be compatible with both Freundlich and Langmuir isotherm models. The maximum CPX adsorption capacity of PPBPA was calculated to be 153.9 mg/g from the Langmuir equation. CPX adsorption increased with increasing temperature, indicating that the adsorption was endothermic. Adsorption/desorption experiment results showed that CPX desorption efficiency was higher within 0.1 M NaOH than 0.1 M HCl. As a result, this study revealed that PPBPA is an underutilized bioresource with the potential to provide an excellent, low-cost, easy-to-prepare adsorbent for CPX removal in wastewater treatment.