生物炭改性土的甲烷吸附试验研究

Laboratory study on methane adsorption of biochar-modified soil

生物覆盖层是一种新型生活垃圾填埋场覆盖层,对比传统的压实黏土覆盖层其具有较高的甲烷氧化能力,减少垃圾填埋场甲烷的释放。生物炭作为生物覆盖介质,除了提高土壤甲烷氧化能力之外,其较大的比表面积还能增加甲烷吸附能力。为更好地理解生物炭对土壤的甲烷吸附特性的影响,通过批量吸附试验研究生物炭改性土在不同甲烷初始浓度与生物炭掺量下的甲烷吸附能力。试验结果表明添加生物炭能提高土壤甲烷吸附能力,相比较原土,炭掺量为20%的改性土最大甲烷吸附量提高了一个量级,甲烷吸附能力得到明显提高主要得益于生物炭的多孔结构。并且生物炭改性土的吸附特性均符合Lagergren准二级吸附动力模型和Langmuir等温吸附模型。

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.