Low temperature adsorption of nitric oxide on cerium impregnated biomass-derived biochar

This study investigates the catalytic oxidation of NO to NO2 over biomass-derived biochar at ambient temperature. Rubber seed shell (RSS) was used as lignocellulosic waste to develop biochar for NO capture. The NO adsorption capacity of pristine biochar was low, about 17.61 mg/g at 30 degrees C. To enhance the NO uptake capacity of biochar, cerium (Ce) was introduced into the biochar surface through simple impregnation method. Upon this, the NO adsorption capacity of 3 wt% Ce-loaded biochar profoundly increased to 75.59 mg/g at the same adsorption condition. This was confidently due to the excellent oxygen storage capacity of ceria which could react with free active sites on the biochar surface to form oxidized cites C(O). Characterization results indicated that the adsorbed species was in the form of -O-N=O, suggesting that the adsorption of NO was followed by reaction with surface oxidized sites to form NO2. Studying the kinetics of the NO adsorption using pseudo-second order, Avrami and Elovich models showed that chemisorption was the chief mechanism that governed the adsorption process and the activation energy for NO adsorption was estimated to be around 45 kJ/mol.