Enhancing adsorption of nitrate using metal impregnated alumina

• Nitrate adsorption selectivity is increased through Ni impregnation.
• Nickel impregnation shows 13 times increase in capacity.
• The adsorbents were evaluated on water samples from nitrate polluted area.

The adsorption capacity and selectivity are vital for designing economically feasible treatment system for drinking water. This work is aimed at enhancing the selectivity of nitrate adsorption through metal impregnation. Impregnation of Mg, Fe, Co, Ni, Zn and Cu on alumina was investigated. Nickel impregnation was found to be the best, with an increase in 13 times the nitrate adsorption capacity compared to unmodified alumina. The optimal pH for nitrate adsorption using nickel-modified alumina was in a wide range from 3 to 7. The nitrate adsorption capacity was not influenced by the presence of fluorides and phosphates, whereas carbonates and sulphates were found to decrease the adsorption capacity by 50%. The adsorbents were also tested on drinking water samples from Madhya Pradesh, India. The nitrate adsorption capacity of nickel-impregnated alumina was still 10 times higher compared to the bare adsorbent.

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