CaCO3-ZnO loaded scrap rice-derived biochar for H2S removal at room-temperature: Characterization, performance and mechanism

Metal oxide loaded carbon-based materials have attracted extensive attention as promising desulfurizers to solve the problem of H2S emission at room temperature. However, low desulfurization capacity, difficult regeneration and high economic cost are the main problems of metal oxide loaded carbon-based desulfurizers, which limit their industrial application. Herein, a novel and low-cost CaCO3-ZnO loaded biochar (RCZ) was synthesized by one-step pyrolysis of scrap rice and metal salts for highly efficient H2S removal at room-temperature. The optimized RCZ-1-1-1-800 sample showed an excellent H2S removal ability of 834.48 mg/g at the reaction temperature of 25 °C, oxygen content of 10%, and relative humidity of 70% as compared to 29.31 mg/g achieved by the inactivated biochar (prepared without activator). Such an RCZ-1-1-1-800 desulfurizer also delivered a high H2S removal ability under different desulfurization conditions. The associated desulfurization mechanism of RCZ was the coupling of reactive adsorption and catalytic oxidation with sulfur being the main desulfurization product. Moreover, the as-fabricated RCZ also exhibited a high reusability, retaining about 95% of the initial H2S removal capacity after five adsorption/regeneration cycles. This work provides a promising idea for the preparation of low-cost and high-capacity metal oxide- and carbonate-loaded carbon-based desulfurizers.