Dynamic Adsorption of Nitric Oxide (NO) in a Fixed-bed Reactor Using Rubber Seed Shell-derived Biochar

Abstract

Control of nitric oxide emission (NO) as the main constituent of nitrogen oxides (NOx) from combustion sources is a global concern. In this context, this study investigates the adsorption of NO using some biomass-derived adsorbents. Rubber seed shell (RSS) was used as a lignocellulosic residue to develop biochar, modified by metal-doping and alkali activation. The prepared adsorbents, namely, pristine biochar, cerium-loaded biochar and KOH-activated biochar, were used to capture NO in a dynamic fixed-bed adsorption system. The effect of different initial NO feed concentrations (200 and 350 ppm), total gas flow rates (100, 150 and 200 ml/min), and adsorption temperatures (30, 70 and 110 oC) on the adsorption capacity of the adsorbents was investigated. The most suitable operating condition for NO adsorption was found to be the NO feed concentration of 200 ppm, inlet gas flow rate of 100 ml/min and the adsorption temperature of 30 oC at which the high NO adsorption capacity of 81.67, 142.53 and 470.50 mg/g was attained for pristine, Ce-loaded, and KOH-activated biochars, respectively. The adsorbents showed high sustainability in the regeneration process within 5 cycles of NO adsorption-desorption. These results highlight the high potential of RSS-derived biochar for the control of NOx emission from flue gases.