Abstract:Non-ferrous smelter flue gas is a major anthropogenic source of arsenic emissions in China. Because the composition of non-ferrous smelter flue gas is complicated, efficient removal of gaseous arsenic remains a significant challenge. Biomass charcoal usually contains abundant functional groups on its surface, which have a strong affinity for arsenic. Therefore, a modified biomass charcoal adsorbent was synthesized by hydrothermal method from Camellia oleifera shell. The analysis and characterization results of the adsorbents confirmed that the prepared biomass charcoal has a porous and spherical structure with a large specific surface area (532 m2/g) and a well-developed microporous structure (0.647 cm3/g). Infrared spectroscopy confirmed that the prepared biomass charcoal also contains a large number of oxygen-containing functional groups such as C—O and C=O. Gaseous arsenic adsorption experiments determined that the optimal adsorption temperature of biomass charcoal for arsenic is 400 ℃, and its maximum arsenic adsorption capacity reaches 16.14 mg/g, which is superior to that of traditional mineral adsorbents. The adsorption capacity of biomass charcoal adsorbent at the concentrations of 8 g/kg SO2, 10 g/kg HCl, and 16% CO2 maintained an adsorption capacity above 10 mg/g, demonstrating a strong resistance to acid gas poisoning. Furthermore, the presence of O2 in smelting flue gas enhances arsenic removal, whereas H2O has a slight inhibitory effect. The final arsenic adsorption product was characterized using X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma-high performance liquid chromatography (ICP-HPLC) techniques. The dominant arsenic species in the adsorption product is As5+, which accounts for 62.7% of total arsenic at 250 ℃ and under a pure N2 atmosphere. Upon increasing the adsorption temperature to 400 ℃ and O2 volume concentration to 6%, the proportion of As5+ increases to almost 100%, indicating that arsenic oxidation plays a crucial role in arsenic removal. The proposed arsenic removal mechanism involves the physical adsorption of gaseous arsenic trioxide on the biomass charcoal surface, followed by oxidation to stable diarsenic pentoxide by the oxygen-containing functional groups, ultimately leading to arsenic purification. The spent biochar can be regenerated through alkaline boiling. After 10 cycles, the arsenic removal of biomass charcoal decreased by only 30%, demonstrating that the biomass charcoal from Camellia oleifera shell exhibits good regeneration potential. The above results demonstrate the excellent industrial application potential of biomass charcoal for arsenic pollution control. Close-