Abstract Untreated low methane (CH4) content (less than 10%) landfill gas within the post-methanogenic stage is currently vented into the atmosphere, constituting an important source of anthropogenic greenhouse gas (GHG).… Click to show full abstract
Abstract Untreated low methane (CH4) content (less than 10%) landfill gas within the post-methanogenic stage is currently vented into the atmosphere, constituting an important source of anthropogenic greenhouse gas (GHG). Development of a proper mitigation process for low CH4 gas is therefore necessary for landfills. In this study a special photocatalyst, Y2O3:Er3+-TiO2-0.05% graphene (GR), was synthesized by sol-gel method and then characterized; it showed a good response to visible-near-infrared (Vis–NIR) sunlight. The corresponding absorption edge was 354 nm, and upconversion fluorescence peaks of ultraviolet (364 nm) and violet (408 nm) emissions were acquired under 980 nm excitation. Y2O3:Er3+-TiO2-GR was developed and tested for removal of low CH4 landfill gas under Vis–NIR light irradiation, and a maximum photodegradation rate of 45.1% for CH4 was obtained using the photocatalyst Y2O3:Er3+-TiO2-0.05% GR with a light intensity of 2050 mW m−2. The corresponding CH4 content decreased from 10% to 5.5%, mitigating almost half of GHG during the post-methanogenic stage. The intermediate products of CH4 degradation were CO, OH, O−, CO2 and H2O traced by in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). This research proposes a new approach for reducing the GHG effect of low CH4 content landfill gas.
               
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