In the present study, raw radish biomass (RB) and chemically modified biomass (CMB) were used as biochar to remove fluoride from the solution of fluoride prepared in tap water. The CMB was prepared by treating RB with magnesium chloride to enhance the efficiency of the process by imparting more functional group to the biochar. Both the biochar was characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, pHZPC, particle size analysis and X-ray diffraction for crucial surface morphology and chemical composition. The process of adsorption was optimized by conducting a batch adsorption study. Reliability of the biosorption was validated with the help of isotherms (Langmuir, Freundlich and Temkin) and chemical kinetics. The CMB was found to be more efficient in fluoride removal as compared to RB. The maximum removal of fluoride was observed to be 45% and 90.5%, at pH 4 by RB and CMB, respectively, at atmospheric temperature. Pseudo-second-order kinetics was best fitted to the experimental data of fluoride adsorption by both the biochar. Probable adsorption mechanism comprised of hydrogen bonding, electrostatic attraction and fluoride complexation.
