Abstract
Biochar-amended soil cover (BSC) in landfills can improve the oxidation of methane. However, adding biochar can cause a larger amount of rainwater to enter the soil cover and landfill because it increases the permeability of the soil cover, which increases leachate production. Improving the hydrophobicity and waterproof ability of BSC is expected to reduce rainwater that goes into landfills. Silane coupling agent KH-570 is used to modify biochar to improve its hydrophobicity and waterproof ability after being added to the soil cover. The waterproofness of hydrophobic biochar-amended soil cover (HBSC) was studied by conducting a precipitation simulation test. Results showed that the optimum hydrophobicity of the surface-modified biochar was obtained when the mass fraction of KH-570 was 7%, the biochar dosage was 7 g, and the modification temperature was 60 °C. In these conditions, the contact angle was 143.99° and the moisture absorption rate was 0.10%. The analysis results of thermogravimetric, X-ray diffractometer and scanning electron microscopy before and after the biochar modification showed that KH-570 formed a hydrophobic organic coating layer on the biochar surface, indicating that the surface hydrophobic modification of biochar was successfully carried out by silane coupling agent. The waterproof ability of HBSC was significantly better than that of BSC in the simulated precipitation test.
Highlights
Landfill soil cover has been used to oxidize methane to reduce methane emission [1,2].The CH4 emission reduction of landfill depends on the choice of soil cover material
In this study, silane coupling agent KH-570 was selected as the modifier to conduct an experiment on hydrophobic modification of biochar, thereby improving its hydrophobicity and reducing rainwater that enters the soil cover and landfill
Properties of various mass fractions of KH-570 on the surface hydrophobicity of biochar were in
Summary
Landfill soil cover has been used to oxidize methane to reduce methane emission [1,2]. In contrast to traditional soil cover, the biocover in landfill have been extensively studied to increase the aerobic oxidation of methane [3]. The increase of permeability coefficient leads to the increase of rainwater into the methane oxide layer and landfill. Water content has been found to be an important environmental factor that controls methane oxidation and adsorption capacity of landfill cover soil [17,18]. In this study, silane coupling agent KH-570 was selected as the modifier to conduct an experiment on hydrophobic modification of biochar, thereby improving its hydrophobicity and reducing rainwater that enters the soil cover and landfill. The hydrophobic modification of biochar was conducted to develop materials to improve the hydrophobic permeability of the landfill cover layer, providing technical support for methane emission reduction in landfills
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