Bentonite for ciprofloxacin removal from aqueous solution

Ciprofloxacin hydrochloride (CIP) is the second generation of fluoroquinolone antibiotics whose residues are found in wastewater and surface water. CIP has high aqueous solubility under different pH conditions and high stability in the soil system. In this study, bentonite was used as a potential sorbent for the removal of CIP from aqueous solutions using batch experiments. The effects of various parameters such as contact time, pH, adsorbent dosage, agitation speed, ionic strength and initial concentration of CIP in aqueous solution on the adsorption capacity were investigated. The optimum contact time, pH, agitation speed and adsorbent dosage were found to be 30 min, 4.5 pH, 150 rpm and 2.5 g L-1, respectively. When the ionic strength was increased from 5 to 50 mM, the adsorption of CIP decreased from 97.8 to 93.4%. The isotherm adsorption data fitted well with the Langmuir model, K-l and q(e) were found to be 0.27 L mg(-1) and 147.06 mg g(-1), and the data fitted well with the pseudo-second order kinetics, whereby k was found to be 2.19 g mg(-1) h(-1)