Development of a tea waste-based mixture for the removal of fluoride in water
A case study with selected concentrations of fluoride in water
Keywords:tea waste, laterite, fluoride, sorption
The main objective of this study is to investigate the sorption behavior of fluoride in tea waste under various fluoride concentrations in water in Sri Lanka to study the fluoride removal from drinking water. The physicochemical characteristics of tea waste were investigated using SEM, AAS, BET, and FTIR analysis. The results obtained by batch experiments showed that the maximum percentage removal efficiency of 42.58±0.97 was at pH 6, after 20 min of contact time, and with an adsorbent dose of 1.5 g. The adsorption equilibrium isotherms followed by the Langmuir model, and the reaction obeyed the pseudo-second-order model. Phosphate ions have shown maximum influence on fluoride removal by the tea waste-laterite mixture. A mixture containing 65% tea waste and 35% laterite showed the highest removal efficiency with a maximum adsorption capacity of 0.0216 mg/g. Finally, a fluoride removal setup was prepared and the filtering performance of the tea waste-based mixture was studied under selected influent fluoride concentrations of 1.5 ppm, 2.0 ppm, and 2.5 ppm, respectively. The results of this experiment showed that each filtering set-up with different influent concentrations had significant fluoride removal efficiency to the WHO drinking water quality standard limit of 1.5 ppm. The optimum fluoride removal happened at pH6 in both batch experiments and filtering set-up experiments. Therefore, the material can be applied for fluoride removal without changing the normal pH of potable groundwater.