Application of iron impregnated activated carbon for removal of arsenic from water

The presence of arsenic in drinking water is one of the greatest threats to public health. The aim of this experimental investigation was to study the removal efficiency of As [v] from water by application of iron-impregnated activated carbon [Fe-AC]. Coating of activated carbon with iron salt was carried out by impregnation method and thermo-chemical reactions with using of 100 mM FeCl3 solution. The Fe-AC was pulverized using ASTM standard sieves with the range of 16-20 mesh. The solid structure and surface characteristics of Fe-AC were determined using conventional techniques. Batch adsorption experiments were carried out with 300 and 600 micro Lig/L arsenate. Langmuir, Freundlich and Dubinin-Radushkevich models were used to describe the isotherm and energy of adsorption. The results of this study showed that 2.5 h contact time was enough to achieve the equilibrium. The adsorption of As [v] had a good compliance with Langmuir model [R[2]= 0.995] and the maximum adsorption capacity was obtained as 0.024 mg/g. The results of kinetic studies showed that As[v] adsorption on Fe-AC may be limited by film diffusion step [m=0.26]. The mean free energy of adsorption [E] calculated from Dubinin-Radushkevich isotherm was found to be 1.52 kj/mol which implies that the adsorption of As[v] on Fe-AC is a physical adsorption. The results indicated that Fe-AC is one of the suitable adsorbents which can be used for the treatment of arsenic contaminated waters

[Heavy metal removal from aqueous solution by adsorption on modified banana shell]

Heavy Metals in Water resources is one of the most important environmental problems of countries. Up to now various methods of removing of these metals is considered, which is including using of low prices materials. In this study the potential of banana shells was assessed for adsorption of heavy metal ions such as Pb and Cd from aqueous solution. Banana shells were pretreated separately with 0.4 mol/L NaOH, 0.4 mol/L HNO and distilled water and their adsorption ability were compared. Batch adsorption experiments were carried out as a function of the initial ion concentration, pH and adsorbent dosage. Adsorption isotherms of metal ions on adsorbents were determined and correlated with common isotherm equations such as Lungmuir, Freundlich and BET models. The maximum adsorption capacities were achieved by alkali modified banana shells [36 mg/g] for Pb and by acidic modified banana shells [16 mg/g] for Cd. Experimental results showed that the best pH for adsorption was 6 and the adsorption values decreased with lowering pH. Isotherm models indicated best fit for Freundlich model for modified banana shells. In comparing the parameters of models, it was observed that the capacity of banana shells for adsorption of lead is higher than for adsorption of cadmium, but the adsorption of cadmium is stronger than the adsorption of lead