Utilization of bagasse fly ash for the production of low-cost ammonia adsorbents in poultry farm

Mechanistic insights into oxychar' s role in mitigating ammonia volatilization from fertilised alkaline soils

Mitigating ammonia (NH3) volatilization from fertilised alkaline soils is crucial for promoting environmental sustainability and safeguarding public health. In this study, "oxychar" was prepared from an agricultural waste via a low-temperature partial-oxidation (LTPO) process under oxygen-sufficient environment. The optimum modification temperature was 220 °C for a duration of 3 h, yielding a maximum NH3 uptake of 76.4 mg/g by oxychar. The enhanced adsorption capacity and stability are attributed to the increased surface oxygen-containing functional groups (OCFGs) that act as adsorption sites, as well as the presence of ultra-micropores that facilitate effective trapping. When applying optimised oxychar to 21-day incubation studies, it is found that cumulative NH3 volatilization is reduced by 76.3 %-91.6 % with oxychar application rates of 1 %-3 %, compared to urea treatments. Soil property and microbial community analyses further indicate that oxychar promotes the hydrolysis of urea and the reduction of nitrate to ammonium by dissimilation (DNRA) processes while inhibiting nitrification by modulating microbial communities, resulting in higher ammonium and lower nitrate levels in soil compared to urea treatment. However, the enriched ammonium cannot volatilize freely due to the chemisorption of ammonium and NH3 by oxychar via ionic and covalent bonds, respectively. Introducing oxychar to soil could be a promising approach to mitigate NH3 volatilization from fertilised soil to ensure food security and environmental sustainability.

Production of bagasse fly ash-derived CO2 adsorbent by physical activation and by nitrogen-functionalization using hydrothermal treatment

The high cost of commercial CO2 capture material is one of the issues hindering the widespread adaptation of the technology. This study explored efficient ways of utilizing waste material in the form of bagasse fly ash (BFA) as CO2 adsorbent through thermochemical preparations of physical activation, and hydrothermal carbonization (HTC). The activation of BFA using flue gas was able to produce an adsorbent with good CO2 adsorption capacity, with similar results to the CO2 activation. The second approach using co-HTC of BFA with chicken manure (CM) optimized using Box-Behnken design of experiment was able to produce an adsorbent with CO2 adsorption capacity nearly on-par with commercial adsorbents. It was also found that the model was able to accurately predict the experiment outcome when verified with the additional experiments. Material characterizations showed that the increase of the CO2 adsorption capacity of the adsorbent might have been achieved through the formation of secondary amines deposited on the BFA. The results of this study showed that the utilization of waste in the form of BFA and CM could contribute to the advancement of circular and low-cost CO2 capture medium from waste materials, which could increase the adaptation and involvement of sugar industry and poultry farm.