Application of ZnO Nanoparticles in Control of H2S Emission from Low-Temperature Gases and Swine Manure Gas

Abstract

Zinc oxide nanoparticles were evaluated for the removal of hydrogen sulfide from low-temperature gases, as well as swine manure gas using laboratory and semi-pilot scale systems. Effects of gas flow rate (200 and 450 mL min−1), H2S concentration (90–1500 ppmv), temperature (1–41 °C), and particle size (18, 80–200 nm) were investigated in the laboratory scale system using premixed gases (H2S-balanced N2). The breakthrough and equilibrium adsorption capacities increased with an increase of H2S concentration. Application of high gas flow rates saturated the adsorbent faster and decreased the adsorption capacities. Adsorption capacities of 18 nm particles were higher than those of 80–200 nm. Regardless of H2S concentration, the equilibrium adsorption capacity was not affected by temperature in the range 1 to 22 °C but increased when a higher temperature of 41 °C was applied. Among the evaluated isotherms, Langmuir-Freundlich described the equilibrium data obtained with 18 and 80–200 nm particles with a higher level of accuracy. Experiments in a semi-pilot scale adsorption system with 18 nm ZnO and gases emitted from the stored swine manure demonstrated the effectiveness of ZnO nanoparticles in removal of H2S from these representative gases. Specifically, treatment of manure gas in the semi-pilot scale adsorption system decreased the level of H2S from an average inlet value of 235.7 ± 85.2 ppmv to a negligible level.