A novel acid modified alumina adsorbent with enhanced defluoridation property: Kinetics, isotherm study and applicability on industrial wastewater

Abstract

Excessive fluoride contamination in ground and surface water is hazardous to human health. Adsorptive removal is a better option for defluoridation due to its simplicity and efficient working property. In the current research, an attempt was made for the removal of fluoride ions from wastewater by a novel adsorbent synthesized with alumina and H2SO4 acid by acidic activation. The adsorbent was characterized for physio-chemical properties by several analytical methods (SEM, EDX, FTIR, XRF, TGA, XRD, HI and pHZPC). The specific surface area of acid activated alumina (AAA) adsorbent was found to be 87.44 m2/g. The batch scale experiments were conducted to study the effect of initial pH, adsorbent dose, stirring rate, and contact time on the defluoridation efficiency of AAA adsorbent. The experimental data of isotherm study was found to follow the Freundlich isotherm model. The maximum adsorption capacity of fluoride on AAA was 69.52 mg/g at 318 K. The nature of adsorption was found to be endothermic and spontaneous. The adsorption kinetic data followed the pseudo-second-order model. The fluoride removal efficiency of alumina with and without acid activation resulted in 96.72% and 63.58%, respectively. The regeneration capability, reusability, applicability on industrial effluent and economic value were investigated.