Optimization of defluoridation using Ficus benghalensis leaf biosorbent through Taguchi's method.

Abstract

Present research focuses on optimization of process parameters for defluoridation on novel Ficus benghalensis leaf biosorbent using Taguchi design tool. The maximum fluoride removal is obtained at pH 7, initial concentration 5mg/L, contact time 120min, adsorbent dose 10g/L, and temperature 30°C, and its percentage contribution is found using ANOVA in the following order: pH 50.76%>initial concentration of adsorbate 44.76%>contact time 2.54%>adsorbent dose 1.17%>temperature 0.76%. It follows Langmuir isotherm with constants "a" and "b" obtained as 2.183mg/g and 0.667L/mg and fitting well with pseudo-second-order kinetic model. The thermodynamic study indicated the spontaneous and endothermic nature (ΔH=15,530.55J/mol). Advanced Analyses, viz., BET, FESEM-EDS, and FTIR are done to know the characteristics of Ficus benghalensis leaf biosorbent. Experiment on defluoridation of contaminated groundwater indicated over 90% removal efficacy, and the concentration of treated water satisfies drinking water standards for fluoride. PRACTITIONER POINTS: A fundamental research leading towards development of a novel biosorbent from Ficus benghalensis leaves waste for defluoridation. Necessary adsorption equilibrium, kinetic and thermodynamic studies to arrive at optimum operating parameters using Taguchi method and constants useful for designing defluoridation unit and advanced analysis mainly BET, FESM-EDS and FTIR to have better insight. Validation on real field samples to prove its technical feasibility of defluoridation using the novel biosorbent developed.