Cu/TiO2 adsorbents modified by air plasma for adsorption-oxidation of H2S.

In this study, non-thermal plasma (NTP) was employed to modify the Cu/TiO2 adsorbent to efficiently purify H2S in low-temperature and micro-oxygen environments. The effects of Cu loading amounts and atmospheres of NTP treatment on the adsorption-oxidation performance of the adsorbents were investigated. The NTP modification successfully boosted the H2S removal capacity to varying degrees, and the optimized adsorbent treated by air plasma (Cu/TiO2-Air) attained the best H2S breakthrough capacity of 113.29 mg H2S/gadsorbent, which was almost 5 times higher than that of the adsorbent without NTP modification. Further studies demonstrated that the superior performance of Cu/TiO2-Air was attributed to increased mesoporous volume, more exposure of active sites (CuO) and functional groups (amino groups and hydroxyl groups), enhanced Ti-O-Cu interaction, and the favorable ratio of active oxygen species. Additionally, the X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results indicated the main reason for the deactivation was the consumption of the active components (CuO) and the agglomeration of reaction products (CuS and SO42-) occupying the active sites on the surface and the inner pores of the adsorbents.

Cu/ACF adsorbent modified by non-thermal plasma for simultaneous adsorption-oxidation of H2S and PH3.

Non-thermal plasma (NTP) surface modification technology is a new method to control the surface properties of materials, which has been widely used in the field of environmental protection because of its short action time, simple process and no pollution. In this study, Cu/ACF (activated carbon fiber loaded with copper) adsorbent was modified with NTP to remove H2S and PH3 simultaneously under low temperature and micro-oxygen condition. Meanwhile, the effects of different modified atmosphere (air, N2 and NH3), specific energy input (0-13 J/mL) and modification time (0-30 min) on the removal of H2S and PH3 were investigated. Performance test results indicated that under the same reaction conditions, the adsorbent modified by NH3 plasma with 5 J/mL for 10 min had the best removal effect on H2S and PH3. CO2 temperature-programmed desorption and X-ray photoelectron spectroscopy (XPS) analyzes showed that NH3 plasma modification could introduce amino functional groups on the surface of the adsorbent, and increase the types and number of alkaline sites on the surface. Brunauer-Emmett-Teller and scanning electron microscopy showed that NH3 plasma modification did not significantly change the pore size structure of the adsorbent, but more active components were evenly exposed to the surface, thus improving the adsorption performance. In addition, X-ray diffraction and XPS analysis indicated that the consumption of active components (Cu and Cu2O) and the accumulation of sulfate and phosphate on the surface and inner pores of the adsorbent are the main reasons for the deactivation of the adsorbent.