Guar Gum Hydrogel Beads for Defluoridation from Aqueous Solution: Kinetic and Thermodynamic Study

In the present research work, batch adsorption study was carried out to optimize the fluoride removal capacity of guar gum hydrogel beads from aqueous solution. The adsorption capacity was found to be 71.2 mg/g. The FTIR spectrum revealed the presence of functional groups that might be involved in fluoride adsorption. Adsorption of fluoride onto bio-sorbent was investigated as a function of pH, adsorbent dosage and time. The experimental equilibrium sorption data well fitted to the Langmuir mo del and the sorption kinetics for the bio-sorbent was found to follow second order rate expression. The negative values of ΔG° suggest that the sorption of fluoride onto the bio-sorbent was spontaneous and exothermic due to the negative value of ΔH°. The negative ΔS° value for the guar gum was found to be decreasing in randomness at the solid-liquid intersection.