Purification Of Arsine With Cuo_x/TiO₂ Sorbents From Sealed Carbide Furnace Exhaust Under Low Temperature Conditions

The mineral resources are abundant in the southwestern region of China,and the non-ferrous metal smelting industries distribute widely.However,the emission of closed-end calcium carbide furnace plant contains a lot of toxic and harmful gases,such as PH₃,H₂S,AsH₃,HCN,COS,CS₂ and so on.Direct emissions of those harmful gases will cause serious damage to the environment and human physical health.CO is one of the constituent of calcium carbide furnace exhaust,which has excellent utilization for its high calorific.However,the presence of various impurity gases severely limit its use,thus effective measures should be taken to deal with these impurity gases.Among these complex gases,arsine（AsH₃）has a relatively high degree of reduction,acute toxicity,bioaccumulation,and irreversibility to humans and environment.Due to the particularity of AsH₃,few studies of AsH₃ have been performed,so effective control technology needs to be developed.In this paper,the sol-gel method was used to prepare the sorbents to purify AsH₃at low temperatures.The active component,carrier,loading capacity,calcination temperature and pH of sol were screened in the preparation process,and the optimal preparation conditions are as follows:20 wt.%of Cu content,400?C of calcination temperature,10 of pH.Then the adsorption performance of AsH₃ under various experimental conditions（reaction temperature,oxygen content,etc.）were compared.The experimental results show that the optimum adsorption capacity was 534.3 mg/g at a reaction temperature of 120°C and an oxygen content of 2%.To explore the properties of various samples and the adsorption mechanism,specific surface area（N₂-BET）,X-ray diffraction（XRD）,fourier transform infrared（FT-IR）,carbon dioxide-programmed temperature desorption（CO₂-TPD）and X-ray photoelectron spectroscopy（XPS）were recorded on the target material before and after the reaction.According to characterization results,the TiO₂ crystal phase in CuO_x/TiO₂sorbent（pH=10）mainly existed in the form of anatase structure,which had a largest specific surface area,a more developed pore structure,more basic adsorption sites and the particle size was more uniform than other samples.These excellent structural characteristics and properties of the CuO_x/TiO₂ sorbent（pH=10）were responsible for the large adsorption capacity of AsH₃.In the reaction process,arsine was oxidized by the lattice oxygen from CuO_x/TiO₂ sorbent（pH=10）activated by O₂,and the main products were As₂O₃ and H₂O.TiO₂ might not participate in the reaction itself,but the interaction between CuO and TiO₂ could promote the adsorption of AsH₃.While increasing the temperature,the arsine breakthrough adsorption capacity and the product As₂O₅ were increased.As the reaction gone on,AsO_x agglomerated on the sorbents surface thus block the pore,resulting in a gradually weakness of adsorptive performance of AsH₃.In this paper,the N₂ heating purging method was conducted to study the regeneration performance of the sorbent,the number of regeneration and the adsorption capacity of the sorbent after regeneration were used to evaluate the regeneration performance of the adsorbent.The regeneration experiment results illustrated that the sorbent after regeneration could restore most of the adsorption performance,therefore it had en excellent regeneration effect.The sorbent efficiently converted gaseous AsH₃ into solid As₂O₃ and As₂O₅,which are less toxic and easier to handle.And these As₂O₃ and As₂O₅ could be collected in a catcher located downstream.The adsorption capacity reached 534.3 mg/g of CuO_x/TiO₂,and exhibited a excellent regeneration performance,which has a good prospect of industrial application.