Synthesis and Characterize of Zeolite- Zero Valent Iron/ Silver Nanocomposite (Z-Fe0/Ag) for Removal Fluoride in Aqueous Solutions (Study of Isotherms, Kinetics and Thermodynamics)

Fluoride is a pollutant that entered to the environment through Glass, Fertilizer and Semiconductor Material industries and cause problems such as Alzheimer's and brain injuries. Adsorption with using inexpensive materials like zeolite is the best options to remove this pollutant. The main problem of absorption method is its low speed. So the aim of present study is investigated the effect of Fe0/Ag nanoparticles as catalyst in performance of zeolite for removal of fluoride. In this study were used reduction method for converting Fe2+ to Fe0 and co-precipitation method for coating of Fe0 on Zeolite. For depositing silver on nano zero valent iron the rapid mixing along with the high temperature were used. Absorbent characteristics were analyzed with using SEM, TEM and XRD techniques. Then effect of pH, contact time, stirring speed, temperature, amount of adsorbent and Fluoride concentration were evaluated and optimized. pH=3, 60 min contact time, 200 rpm stirring speed and adsorbent concentration equal to 10g/l were obtained as the optimum conditions for Fluoride removal. Investigating the isotherms and kinetics relationships showed that the experimental data correlate to the Langmuir adsorption isotherm model (R2>0.991) and pseudo-second order kinetics (R2>0.933). The reaction thermodynamic study also expressed that process is endothermic and non-spontaneous According on the obtained results can be stated This Absorbent has appropriate efficiency in fluoride removal, But the catalytic properties of zero valent iron and silver was rejected in relation to removal this contaminants.