This paper presents the synthesis of iron(III)-aluminum(III) mixed oxide with some of its physicochemical characteristics and fluoride adsorption behavior thereon. Results showed that the optimum initial pH for fluoride adsorption is 4.0-10.0, and the equilibrium time required is 1.5 h. The isotherm data follow the order Redlich-Peterson g Langmuir > Freundlich > Temkin. The Langmuir monolayer adsorption capacity of the adsorbent is determined to be 17.73 mg/g, which is higher than that of either of the pure oxides. The enthalpy change (∆H°) and entropy change (∆S°) for the adsorption reaction are +29.31 kJ/mol and +116.75 J mol -1 K -1 , respectively. The adsorption is endothermic in nature. The kinetics follows a pseudo-second-order rate equation, and the reaction rate is a multistage-controlled diffusion process. The activation energy for this adsorption reaction is 6.35 kJ/mol.
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