Novel, low cost, environmentally benign and highly-efficient sorbents (Zr-Mg-Al) were studied in batch experiments and column studies for the defluorination of drinking water. The sorbent properties were determined by X-ray diffraction (XRD), N2 adsorption/desorption, and scanning electron microscopy (SEM) analysis. Compared with other sorbents, the fluoride removal of hyotalcites sorbents (Zr-Mg-Al) reached 98.7% in 120 min with the sorbent dose 8 g�L-1, pH=7 and temperature = 20 ?. It really show a potential industrial prospect. The preformed sorbent was obtained through extruding a powder mixture of Zr-Mg-Al. The cylindrical shape of the preformed sorbent is conducive to industrial applications. The adsorption capacity of preformed sorbent (Zr-Mg-Al) reached 47.6 mg�g-1 already in the fix-bed column studies and the effluent fluoride concentration was 0.93 mg�L-1 at a high volume space velocity. The process of adsorption by Zr-Mg-Al composite material followed Freundlich as well as Langmuir isotherms. Adsorption kinetic data of the Zr-Mg-Al sorbent were well described by pseudo-second-order kinetics, suggesting a chemisorption process involving ion exchange. The apparent activation energy was 28.6 kJ�mol-1, indicating a fast adsorption process. The increasing total freedom (?S = 142.1 J�mol-1�K-1) and endothermic nature (?H = 38.2 kJ�mol-1) of the system was confirmed through thermodynamic analysis, which was different from the common molecular adsorption systems. At higher concentrations of coexisting anions (1000 mg�L-1), the fluoride removal declined by about 68%.

Fluoride removal of drinking water on Zr-Mg-Al trimetal oxides

248th National Meeting (2014)

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