Analysis of preservative ability of chitosan on CO adsorption of CuCl-alumina-based composites

Abstract

A common problem encountered in the utilization of CuCl-based CO adsorbents was the oxidation tendency of CuCl under atmospheric conditions, with a rapid decrease in an initial CO adsorption uptake over the storage period. In this work, chitosan-modified CuCl-alumina-based composites were prepared by a wet-impregnation method followed by N2 calcination. With the chitosan to alumina weight ratio of 0.15, the resultant fresh composite named 30Cu-0.15chi-Al (30 wt% Cu+/chitosan impregnated alumina) gave the highest initial CO adsorption uptake (19 cm3/g) among the analyzed samples. Interestingly, this composite also preserved its initial CO adsorption uptake throughout the 30-day air-exposed storage owing to the antioxidant effect of the stable Cu-CN constituted organometallic complexes which had been developed on the composite surface during the calcination step. These Cu complex clusters constructed the oxygen-resistant shield for the doped CuCl which was well dispersed inside the porous structure, as confirmed through the analysis of SEM, EDS and XPS. Besides, this sample achieved a higher CO selectivity factor (5.2) over CO2 because of the CO affinity of Cu1+ions by π complexation reaction. This study pointed out a stably efficient CO adsorbent modified with chitosan, which has a great potential to be industrial remediation of CO pollution.