Calcium and zirconium modified acid activated alumina for adsorptive removal of fluoride: Performance evaluation, kinetics, isotherm, characterization and industrial wastewater treatment

Abstract The discarding of industrial wastewater containing fluoride is hazardous to the health of human and animals. In this research article, a novel adsorbent (CAZ) was prepared by loading calcium and zirconium oxides on acid activated alumina. The physiochemical properties of the adsorbent were characterized by various analytical methods. The SEM/EDX and BET results exhibited considerable changes as a result of loading the calcium and zirconium on acidically activated alumina. The FTIR and XRD analysis results demonstrated the successful adsorption of fluoride ions on CAZ. The maximum defluoridation efficiency (97%) of CAZ was achieved at optimized initial pH 6 and adsorbent dose of 6 g/L. The pHzpc of CAZ was found at 6.9. The fluoride adsorption on CAZ followed the Langmuir isotherm and pseudo-second-order kinetics model. The Qmax of CAZ (249 µmol/m2; 216 mg/g) was found to be significant higher than that of parent alumina (19 µmol/m2; 27 mg/g) at 323 K. The adsorption of fluoride on CAZ was found to be endothermic, and spontaneous. The CAZ adsorbent (92%) exhibited satisfactory defluoridation performance of industrial wastewater ( F - contamination − 12.4 mg/L) which was better than the parent alumina (74%). These results demonstrated that CAZ can be a promising adsorbent for effective defluoridation of wastewater.