Optimization of different process parameters for the removal efficiency of fluoride from aqueous medium by a novel bio-composite using Box-Behnken design

Abstract

The present research work approaches the removal of fluoride from contaminated water using mucilage-based bio-composite in a batch mode method. The Box-Behnken design (BBD) is applied successfully for the optimization of the model for the feasibility of the adsorption process. The combined consequences of different investigational variables like pH, bio-composite dosage, and experimental time at constant fluoride concentration and room temperature are studied systematically to know the optimum condition. Adsorption results of fluoride are best fitted to a linearly transformed Langmuir isotherm model with R2 (correlation coefficient) > 0.999. The pseudo-second-order model description of the kinetics of fluoride is effectively applied to forecast the rate constant of the removal process. The maximum adsorption efficiency of bio-composite for fluoride was considered to be 98.62 % at pH 6.5, at optimum conditions of the experimental time of 70 min, the bio-composite dosage of 6 g/L, initial fluoride concentration 10 mg/L, and at room temperature, respectively. The column studies were also investigated to know the breakthrough point and saturation times at different bed heights with an initial concentration of 10 mg/L. The Box-Behnken design is working accurately for the statistical significance of the model (ANOVA test). The study gives more than 95 % adsorption efficiency with respect to the predicted value obtained using the model. To know the adhesion of fluoride on the treated bio-composite materials was distinguished by different instrumental analyses which are thermogravimetric and differential thermal analysis, scanning electron microscopy-energy dispersive X-ray spectroscopy, Fourier transforms infrared spectroscopy and X-ray diffraction.