Development and tailoring of amino-functionalized activated carbon based Cucumerupsi manni Naudin seed shells for the removal of nitrate ions from aqueous solution

Abstract

The removal of nitrate ions with ethylenediamine (EDA)-functionalized activated carbon (AC-NH2) was studied in this work. Activated carbon prepared from Cucumerupsi manni Naudin seed shells using ZnCl2 (ACZ) was functionalized with EDA via a nitric acid oxidation followed by acyl chlorination and amidation process. The effect of pH, contact time, initial concentration and co-existing ions on the adsorption of nitrate ions have been investigated. The FTIR and elemental analysis revealed that amino groups were successfully grafted onto the ACZ after functionalization. The surface area and average pore of ACZ were found to be 1008.99 m2/g and 2.02 nm respectively. However, it was noticed that, after functionalization (AC-NH2), its surface area decreases to 113.43 m2/g meanwhile, its pore diameter increases to 2.48 nm. The experimental results of adsorption showed that AC-NH2 exhibit excellent nitrate ions uptake performance compared to ACZ which is attributed to the presence of the grafted amino groups on the ACZ. Nitrate adsorption follows pseudo-first-order kinetic model while the equilibrium adsorption data was best fitted the Freundlich isotherm suggesting that the adsorption process was predominated by physisorption. This study demonstrates that the prepared AC-NH2 is a promising adsorbent for nitrate ions removal from aqueous media.