Arsine adsorption in copper-exchanged zeolite under low temperature and micro-oxygen conditions

Abstract

Arsenic pollution is a worldwide issue. Nearly all arsenic is converted to arsine (AsH₃) under the reducing atmosphere required for the gasification process. Growing industrialization has increased AsH₃ emissions, for example, the ore smelting process leads to AsH₃ emissions. The conditions used in the ore smelting process are low temperature and micro-oxygen. A series of Hβ zeolites loaded on different metal oxides has been prepared using an impregnation method and tested for adsorption of arsine (AsH₃) under low temperature and micro-oxygen conditions. Based on the results obtained from the adsorbent optimization experiments, Hβ zeolite modified with Cu(NO₃)₂ (denoted as Cu/Hβ) was found to possess a significantly enhanced adsorption removal ability towards arsine. The effects of the impregnation concentration, calcination temperature, reaction temperature, and oxygen content on the AsH₃ removal process were investigated. The results indicate that adsorbents with 0.2 mol L⁻¹ Cu(NO₃)₂ after calcination at 400 °C have superior activity for AsH₃ removal. In addition, a breakthrough capacity of 43.7 mg AsH₃/g adsorbent at 60 °C as well as 1.0% oxygen was observed with Cu/Hβ for the AsH₃ adsorption process. The structure and surface properties of the Hβ zeolite samples were characterized by N₂-BET (N₂ adsorption/desorption), XRD (X-ray powder diffraction), XPS (X-ray photoelectron spectroscopy), and FTIR (Fourier transform infrared) spectroscopy. It is feasible that the exhausted Cu/Hβ can be regenerated by thermal desorption, and the adsorbents can be recycled at least two times with little capacity loss.