A mechanistic insight into defluoridation of simulated wastewater applying bio-inspired sodium alginate bead

Abstract

Abstract The experiment successfully investigated fluoride (F−) uptake capacity of bio-inspired sodium alginate bead (BISAB) using ZSM-5 as an adsorbent through a series of batch studies. The study conducted to observe impact of individual parameter on F− adsorption reveals pH and adsorbent dose to have dominant effect in BISAB uptake as compared to time and temperature. Adsorbent prepared from ZSM-5 with high surface area and micropore volume can adsorb 92% of fluoride at optimized condition. Langmuir, Freundlich, D–R and Tempkin isotherms have been studied for fluoride adsorption. Among all models, Langmuir isotherm fitted exceptionally well over other models; this can be concluded from the regression coefficient obtained for Langmuir model which was very close to 1. The kinetic study suggests F− adsorption onto prepared BISAB to follow pseudo-second-order kinetics of average rate constant 6.5475×10−4 g/fluoride per min. Thermodynamic parameters ΔH°, ΔS° and ΔG° were found to be 10.167 kJ/mol, 29.35 J/mol and − 4.71 to − 13.4444 kJ/mol, respectively. The fluoride adsorption onto BISAB was endothermic reaction.

Keywords

• Adsorption
• Defluoridation
• Modeling
• ZSM-5
• BISAB