Adsorption and Separation of Carbon Dioxide/Methane in Landfill Gas with Barium Ion–Modified Silica Gel

Abstract

Environmental issues caused by greenhouse gases are becoming more and more severe. The main components of landfill gas, carbon dioxide (CO2) and methane (CH4), are greenhouse gases, and the separation and recovery of them are a popular research topic. In order to improve the adsorption capacity of the silica gel adsorbent for landfill gas, a method such as modify silica gel with alkali metal ions is often used. It is to improve the selective adsorption capacity of CO2 by adjusting the polarizability and charge distribution of the silica gel surface while improving the separation effect of the mixed gas. In this study, the adsorption performance of a silica gel adsorbent modified or not with alkali metal ions was measured in terms of the adsorption and separation of a CO2/CH4 mixture (simulating landfill gas). The N2 adsorption and desorption curve of the silica gel adsorbent at 77 K was plotted by determining the specific surface area and pore-size distribution. The results indicated that the unmodified silica gel adsorbent had a large micropore volume and specific surface area and exhibited a high capacity to adsorb gas. After potassium chloride, calcium chloride, magnesium chloride, or barium chloride solution was used to modify the silica gel adsorbent, the adsorption performance of the modified silica gels was ranked as barium chloride > potassium chloride > calcium chloride > magnesium chloride. The best-performing concentration of barium chloride solution was 0.1 mol/L. The research results will provide certain reference for the fields of chemistry and environmental science.