Removal of arsenic from water using calcined Fe-hydrotalcite (K-FeHT)

In this study, the development and characterization of the adsorbent with high surface area, which is effective for removal of arsenic from water, was targeted. For this purpose, the effect of synthesis methods and calcination conditions on the structure of FeHT, known as LDH was investigated. It was observed that the specific surface area of K-FeHT significantly affected by the adsorbent synthesis method, calcination temperature and time. Surface area was obtained 97 m2/g with the optimal synthesis conditions. The surface area was approximately doubled as 173 m2/g at optimum calcination conditions (90 minutes in 450ºC). In consequence of the characterization of the produced adsorbent, it was confirmed that it was compatible with the structure of LDH. As a result of the calcination, H2O, OH- ve CO22- contents between the layers were disappeared, and periclase structures was formed. In adsorption studies, the arsenic concentration of solutions containing 1000 µg/L As was reduced below the permissible value (10 µg/L) with 0.5 and 2 g/L K-FeHT for As(V) and As(III), respectively. The study brought out that the effect of initial pH were limited for the adsorption. The experimental study indicated that the adsorption of arsenic was rapidly occured in comparison with other studies and the pseudo second order kinetic model was more suitable. In isotherm studies, it was seen that the experimental data were compatible with Langmuir model. Arsenic adsorption was not significantly influenced by competitive ions such as SO42-, PO43- ve B(OH)42-. The desorption ratio of As(V) and As(III) were obtained as 72.7 and 20.7%, respectively.