Specific resistance and adsorption performance of acid-modified fly ash for escaped ammonia in flue gas

Escaped ammonia emission following Selective Catalytic Reduction denitrification significantly influences subse-quent flue gas treatment processes. This study investigates the adsorption capabilities of acid-modified fly ash concerning escaped ammonia (NH3) and its consequential impact on specific resistance. Furthermore, the adsorption mechanism of acid-modified fly ash on NH3 was explained. Acid activation facilitated the dissolution of a portion of Fe and Al constituents within the fly ash, the contents of Fe and Al in SFA decrease by 4.91% and 5.64%, respectively. In addition, the specific surface area and porosity of fly ash are obviously improved. The specific surface areas of HFA and SFA increased from 1.83 (OFA) to 4.69 and 7.71 m2/g, respectively. Adsorption kinetics adhered to the pseudo-first-order model. SFA showed the best adsorption performance, with NH3 adsorption up to 10.65 mg/g, which was 4.27 times higher than OFA. The creation of a surface liquid film during NH3 adsorption led to decreased specific resistance values across all fly ash samples after-adsorption. The highest specific resistance values recorded for original fly ash (OFA), hydrochloric acid-modified fly ash (HFA) and sulfuric acid-modified fly ash (SFA) were 6.21 x 1012, 3.37 x 1011 and 5.02 x 1010 omega & sdot;cm, respectively. Sulfuric acid activation makes fly ash have stronger adsorption capacity for escaping ammonia, and SFA maintains good specific resistance character-istics, which has good application prospects in electrostatic precipitation and air pollution control.

Automated summary

This study investigated the adsorption capabilities of acid-modified fly ash for escaped ammonia (NH3) and its impact on specific resistance. The results showed that acid activation improved the specific surface area and porosity of fly ash, leading to enhanced NH3 adsorption performance. Sulfuric acid-modified fly ash exhibited the highest adsorption capacity and maintained good specific resistance characteristics, indicating its potential application in flue gas treatment processes.