Calcium impregnated activated charcoal: Optimization and efficiency for the treatment of fluoride containing solution in batch and fixed bed reactor

The study of de-fluoridation was investigated using calcium impregnated activated charcoal (AC). The sorption efficiency of the modified charcoal was experimented through batch and fixed bed column reactor. Langmuir and Freundlich adsorption isotherm were utilized to study the mechanism of adsorption. The mechanism of adsorption process was illustrated by calculating Gibbs free energy, enthalpy and entropy from thermodynamic studies.The two-level, three-factor (23) Central Composite Design (CCD) expert Software was employed to find the optimum condition of batch process variables for maximizing the fluoride removal capacity of calcium activated hybrid activated charcoal. The optimum removal efficiency was obtained as 99.68%. Furthermore to confirm the practical applicability of this novel adsorbent, fixed-bed column reactor studies were done. The Thomas and BDST models were applied for the column study and it was observed that both model fitted satisfactorily with the experimental results. It can be concluded that calcium impregnated activated charcoal has potential to be a cost effective, environmentally safe adsorbent suitable for fluoride removal from water.