In this study, hierarchical porous biochar was prepared from poplar sawdust by air oxidation coupling with NH₃ treatment for the removal of toluene. The results showed that the mesopore volume of the sample with air oxidation (PS-O₂) increased significantly to 0.263 cm³/g from the blank sample (PS, 0.053 cm³/g). This could be attributed to the selective removal of the lignin carbon by air oxidation to develop mesopores in biochar. Following further NH₃ treatment (PS-O₂-NH₃), the basic surface chemistry on biochar was improved due to increased basic N-containing groups and decreased acidic O-containing groups, together with the micropore volume also increased to 0.231 cm³/g from 0.186 cm³/g of PS-O₂. The formation mechanism of hierarchical porous structure of biochar was also discussed. The adsorption capacity of PS-O₂-NH₃ for toluene reached 218.4 mg/g at the initial concentration of 820 mg/m³, which was 383.2% higher than that of PS. The adsorption isotherm study indicated that the adsorption process of toluene was monolayered and the maximal adsorption capacity of PS-O₂-NH₃ for toluene could reach as high as 476.2 mg/g. The results demonstrated that air oxidation coupling NH₃ treatment is a highly effective method for the preparation of hierarchical porous biochar for enhancing toluene adsorption performance.

在这项研究中，通过空气氧化结合NH ₃处理从杨木锯末制备分级的多孔生物炭，以去除甲苯。结果表明，具有空气氧化作用的样品（PS-O ₂）的中孔体积比空白样品（PS，0.053 cm ³ / g）显着增加至0.263 cm ³ / g 。这可以归因于通过空气氧化选择性除去木质素碳以在生物炭中形成中孔。进一步处理NH ₃（PS-O ₂ -NH ₃），由于增加了碱性含氮基团和减少了酸性含O基团，生物炭的基本表面化学得到了改善，同时微孔体积也从0.186 cm ³ / g PS-O ₂增加到0.231 cm ³ / g 。讨论了生物炭分层多孔结构的形成机理。初始浓度为820 mg / m ^3时，PS-O ₂ -NH ₃对甲苯的吸附容量达到218.4 mg / g，比PS高383.2％。吸附等温线研究表明，甲苯的吸附过程是单层的，PS-O ₂ -NH ₃的最大吸附量甲苯的含量可能高达476.2 mg / g。结果表明，空气氧化偶联NH ₃处理是制备分级多孔生物炭以提高甲苯吸附性能的高效方法。