Abstract
BackgroundA new Bentonite-loaded Pumice adsorbent (P-BNT3) was successfully synthesized as an efficient adsorbent for CIP removal from aqueous solutions. MethodsIn the present study, P-BNT3 composite synthesized by hydrothermal technique (24 h @160 °C) was loaded with Bentonite (BNT) using ultrasonication (20 min @25 °C) to remove CIP antibiotic. P-BNT3 composite was characterized by FTIR, XRD, BET, TGA, SEM, and TEM analyses. XRD, SEM, and TEM analyses indicate effective coupling of Pumice/ BNT strong layers with highly porous heterogeneous structure. Adsorption of CIP is studied as a function of pH, dosage, contact time, initial CIP concentration, and temperature in a batch reactor to obtain the maximum adsorption capacity (qm). Significant FindingsA MFSO kinetic model (R2= 0.983) and Langmuir and Dubinin–Radushkevich isotherm model (R2= 0.989 and 0.986) provide good fits to the experimental. The highest amount of CIP adsorbed is 54 mg/g at pH=2.0, which is 5 folds higher than pristine Pumice. The adsorption equilibrium was attained in 240 min with P-BNT3 for a CIP concentration of 30 mg/L. The characterization of spent composites after CIP adsorption suggested that CIP adsorption onto P-BNT3 composite is governed by π-π interaction, chemical complexation, and surface interactions. Based on thermodynamic investigation over the temperature range of 298 ̶ 318 K, CIP adsorption on P-BNT3 was a spontaneous (-ΔG°) and endothermic (ΔH°=+5.313) phenomenon. Furthermore, the adsorption-desorption procedure demonstrated that the composite could be efficiently reused up to 5 times. However, expensive desorption costs and the inevitable secondary effluent are a challenge in the practical implementation. Based on the findings, the P-BNT3 composite has great potential for the removal of other pharmaceutical compounds.
Published Version
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