Motivation for this study is to combine adsorption active sites of iron(hydr)oxide with high specific surface area and better mechanical resistance of activated carbon, so that the composite can be used efficiently as a filter media for arsenic removal from drinking water. The main objective is to evaluate the arsenic removal efficiency from water using iron(hydr)oxide impregnated activated carbon (AC-Fe) as a filter media. The adsorption behavior of arsenic was evaluated by conducting equilibrium adsorption experiments and kinetic tests. Effects of pH and ionic strength (IS) on arsenic removal efficiency by AC-Fe composite were assessed. Several composites were prepared by varying iron (Fe+3) concentrations from 0.09 M to 3.0 M. Iron content of the AC-Fe composites increases with increasing proportion of iron concentrations that were used during synthesis. Arsenate [As (V)] and arsenite [AS (III)] removed efficiency by different composites were in the range of 92-98% and 42-65%, respectively. The iron impregnated activated carbon containing lowest iron (iron content 1.54%), showed the highest and most consistent arsenate adsorption capacity. This is attributed to the fact that the pore blocking in that composite is negligible with homogeneous iron distribution within the activated carbon pores. Equilibrium adsorption experimental data fitted to the Langmuir model, suggests maximum adsorption capacities for As (V) and As (III) are 1.92 mg and 1.52 mg per gram of AC-Fe, respectively. Arsenic adsorption kinetics is explained well by pseudo-first-order kinetic model within a short time period. Arsenate removal efficiency decreases, whereas arsenite removal efficiency increases with increasing solution pH. Effect of background IS on arsenate removal is negligible and arsenite removal increases with increase in IS beyond 50 mM NaCl. Overall, a small amount of iron, embedded in activated carbon, exhibit promising performance for removal of arsenic from water.

Arsenic removal efficiency by iron impregnated activated carbon for drinking water quality control

247th National Meeting (2014)

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