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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #318534
Title: Removing gaseous NH3 using biochar as an adsorbent

Author
item Ro, Kyoung
item Lima, Isabel
item REDDY, GUIDQOPURAM - North Carolina Agricultural And Technical State University
item Jackson, Michael - Mike
item GAO, BIN - University Of Florida

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2015
Publication Date: 9/30/2015
Citation: Ro, K.S., Lima, I.M., Reddy, G.B., Jackson, M.A., Gao, B. 2015. Removing gaseous NH3 using biochar as an adsorbent. Agriculture. 5:991-1002. doi: 10.3390/agriculture5040991.

Interpretive Summary: Ammonia is a major fugitive gas emitted from livestock operations and fertilization production. Biochar is a carbonaceous byproduct produced from pyrolyzing biomass. This study tested the potential of various biochars in removing gaseous ammonia via adsorption processes. Gaseous ammonia adsorption capacities of various biochars made from wood shaving and chicken litter, different thermal conditions, and activation techniques were determined using laboratory adsorption column tests. The surface area of biochar dramatically increased after activation. Ammonia adsorption capacities of non-activated biochars were comparable to that of other commercial activated carbon and natural zeolite. There were no significant differences in ammonia adsorption capacities of steam activated and non-activated biochars even if the surface areas of the steam activated biochars were about two orders of magnitude greater than that of non-activated biochars. In contrast, phosphoric acid activation greatly increased the biochar ammonia adsorption capacity. The results of this study suggest that non-activated biochars can successfully replace commercial activated carbon in removing gaseous ammonia and the removal efficiency will greatly increase if the biochars are activated with phosphoric acid.

Technical Abstract: Ammonia is a major fugitive gas emitted from livestock operations and fertilization production. This study tested the potential of various biochars in removing gaseous ammonia via adsorption processes. Gaseous ammonia adsorption capacities of various biochars made from two different feedstocks (wood shaving and chicken litter), thermal conditions (250, 480, and 500 degree Celsius), and activation techniques (steam versus acid activation) along with natural zeolite were determined using laboratory adsorption column tests. The surface area of biochar dramatically increased after activation. Ammonia adsorption capacities of non-activated biochars ranged from 0.15 to 5.09 milligram nitrogen per gram biochar (mg-N/g). These adsorption capacities were comparable to that of other commercial activated carbon and natural zeolite. There were no significant differences in ammonia adsorption capacities of steam activated and non-activated biochars even if the surface areas of the steam activated biochars were about two orders of magnitude greater than that of non-activated biochars. In contrast, phosphoric acid activation greatly increased the biochar ammonia adsorption capacity. This suggests that the surface area of biochar did not readily control gaseous ammonia adsorption. Ammonia adsorption capacities were more or less linearly increased with acidic oxygen surface groups of non-activated and steam-activated biochars. Phosphoric acid bound to the acid activated biochars is suspected to contribute to the exceptionally high ammonia adsorption capacity. The results of this study suggest that non-activated biochars can successfully replace commercial activated carbon in removing gaseous ammonia and the removal efficiency will greatly increase if the biochars are activated with phosphoric acid.