Vali-e Asr Avenue, Tehran, Iran
In this study, powdered activated carbon was used as an absorbent to reduce Fe (II) ions concentration of groundwater. The adsorption behavior of Fe (II) ions was studied by varying parameters including the dosage of powdered activated carbon, pH of solution, initial concentration of Fe (II) and contact time. Equilibrium adsorption isotherms and kinetics were also investigated based on Fe (II) adsorption tests. The optimized adsorption conditions were used for reducing iron concentration of groundwater derived from deep wells in Marand Plain with agricultural purposes in April 2017. An increase in contact time and adsorbent dosage resulted in increase of adsorption rate. The optimum condition of Fe (II) removal process was found at pH=4, 0.45 g adsorbent dosage, 10 mg/l initial concentration of Fe (II) and contact time of 30 min. The removal percent was equal to 97.21 at optimal conditions. Langmuir and Freundlich's models were employed to analyze the experimental data. Langmuir model fitted well with the correlation coefficient (R2=0.995) with adsorption capacity of qmax=205.2 mg/g. According to results of analysis of the kinetic data by the pseudo-first-order and pseudo-second-order equations, we found that the adsorption of Fe (II) using PAC follows the pseudo-second-order kinetic model with correlation coefficients (R2) equals to 0.9995, 0.9996 and 0.9993 for 10, 20 and 30 mg/l Fe (II) concentrations, respectively. In addition, the reaction is spontaneous and endothermic. In optimal conditions, this adsorbent can be suitable for improving the quality of ground water containing high iron concentrations.