Laboratory study on methane adsorption of biochar-modified soil

Bio-cover is a novel MSW landfill cover. Compared to the conventional compacted clay cover, it exhibits a higher methane oxidization capacity to mitigate methane emissions from landfill. Use of biochar in the bio-cover can enhance methane oxidization and adsorption capacity because of its high specific surface area. To better understand the effects of biochar on the methane adsorption capacity, a series of batch adsorption tests on a biochar-modified soil are conducted under different initial methane concentrations and biochar contents. The test results show that the methane absorption capacity increases with the increasing biochar content. Compared to the untreated soil, an addition of 20% biochar (weight of dry soil) can increase around 10 times the maximum amount of methane adsorption. It is postulated that the highly porous structure of biochar is the principal factor that enhances the methane adsorption capacity. Furthermore, the pseudo-second order kinetics and the Langmuir isotherm models can be used to evaluate the adsorption process of the biochar-modified soil.