Removing Gaseous NH3 Using Biochar as an Adsorbent

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 wood shaving and chicken litter with different thermal conditions and activation techniques were determined using laboratory adsorption column tests. Ammonia adsorption capacities of non-activated biochars ranged from 0.15 to 5.09 mg·N/g, which 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 NH3 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 sorption capacities of virgin and water-washed biochar samples were OPEN ACCESSAgriculture 2015, 5 992 not different, suggesting the potential to regenerate spent biochar simply with water instead of energy-and capital-intensive steam. 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.

Hydrothermal Carbonization: Modeling, Final Properties Design and Applications: A Review

“…This resulted in three kinetic constants for the Arrhenius equation at constant T (E a 1 = 141 kJ mol −1 , A 1 = 1.89 × 10 14 h −1 ; E a 2 = 75.0 kJ mol −1 , A 2 = 1.15 × 10 7 (1.59) kg −0.52 h −1 ; and, E a 3 = 74.3 kJ mol −1 , A 3 = 1.89 × 10 7 h −1 ). In addition to modelling the HTC kinetics in terms of the three basic biomass components (i.e., hemicellulose, cellulose, and lignin), it will be useful, especially for combustion applications of HC, if the proximate components (i.e., volatile matter, fixed carbon, and ash contents) of the feedstock and HC can be predicted with simple kinetic models, as done by Ro et al [13] for pyrolyzing animal manures. The proximate components of combustion fuels are commonly used to characterize fuel sources by power industry.…”

“…13 C-NMR analysis of HC from glucose revealed that 60% of the carbon atoms are cross-linked furan-based structures directly via either sp 2 or sp 3 type carbon groups [92], in contrast to the higher degree of arene-like structures found in pyrolysis chars from the same substrate [93]. Further 13 C-NMR analyses of chars from livestock waste have shown that, while HCs have a larger degree of aromaticity than pyrochars made at the same temperature (~43-55% vs. 26-32%; 250 • C), the aromaticity of pyrochars increases with increasing production temperature, reaching over 90% (600 • C) [72].…”

“…The bed depth service time model can be used to estimate the adsorption capacity of the HC adsorbents [13]. Mathematical models describing transport and sorption kinetics of adsorbents can be used to examine the effects of various process variables, such as flow, bed depth, etc.…”

Pilot-Scale Testing of Non-Activated Biochar for Swine Manure Treatment and Mitigation of Ammonia, Hydrogen Sulfide, Odorous Volatile Organic Compounds (VOCs), and Greenhouse Gas Emissions

“…Ro et al [6] performed ammonia adsorption capacity experiments on various biochar samples, one of which was produced from wood shavings at a similar temperature (500 • C) to the biochar used in this study and was determined to have an ammonia adsorption capacity of 0.84 mg [NH 3 -N]·g biochar −1 . This reported ammonia adsorption capacity equates to the capacity of the biochar to adsorb only the amount of NH 3 emitted in~one day under the conditions studied for a biochar dose of 4.56·kg·m −2 , i.e., much shorter than observed to be effective in this research.…”

“…Biochar has a long history of being used as a soil amendment. Only recently has biochar been employed in wastewater and manure composting to absorb various compounds (Table 1) and it has been shown to adsorb NH 3 [5,6]. In these recent studies, biochar's ability to mitigate emissions from livestock has focused solely on the land application and composting of manures and on few target gases.…”