Ammonia adsorption capacity of biomass and animal-manure derived biochars

The objective of this research was to characterize and investigate ammonia and hydrogen sulfide gas adsorption capacities of low- and high-temperature biochars made from wood shavings and chicken litter. The biochar samples were activated with steam or phosphoric acid. The specific surface areas and pore volumes of the activated or non-activated biochar samples were evaluated according to the Brunauer, Emmett, and Teller (BET) isotherm model using N ₂ as an adsorbate. The biochar samples were also characterized with energy-disperse X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). Proximate and ultimate analyses were also performed. The biochar samples were placed in a column made of 13 mm × 120 mm PVC pipe. Calibrated ammonia gas with 20 to 100 ppm concentration was passed through the column at 3 LPM. Effluent gas concentration was monitored via a photoacoustic analyzer in order to establish breakthrough curves. The adsorption capacity of the biochar was calculated from integrating the breakthrough curves. To date, we found that ammonia adsorption capacities based on 50% breakthrough curves ranged from 0.25 to 0.75 mg/g for non-activated biochars and 0.1 to 36.2 for activated biochars. The adsorption experiments are still on going and the final results will be presented at the meeting.