Crude oil contaminated lands are recognised to have significant contributions to airborne volatile organic compounds (VOCs) with adverse effects on human health and tropospheric ozone. Soil capping systems for controlling harmful emissions are critical engineering solutions where advanced soil remediation techniques are neither available nor feasible. Studies on the adsorption of single VOC species in biochar have shown promising results as a potential capping material; however, current understanding of mixed gas system and multi-component adsorption of VOCs on biochar which would represent more realistic in situ conditions is very limited. We present, for the first time, the results of a study on competitive adsorption of mixed VOCs, including aromatic and non-aromatic VOCs commonly emitted from crude oil contaminated sites on two types of biochar pyrolysed at 500$°C$ from wheat straw and bagasse as feedstock. The kinetics of sorption of multicomponent VOCs including acetone, hexane, toluene and p-xylene in biochar are studied based on the results of an extensive experimental investigation using a bespoke laboratory setup. Both biochar types used in this study presented a high sorption capacity for VOC compounds when tested individually (51–110 mg/g). For the multicomponent mixture, the competition for occupying sorption sites on biochar surface resulted in a lower absolute sorption capacity for each species, however, the overall sorption capacity of biochar remained more or less similar to that observed in the single gas experiments (50–109 mg/g). The chemical interactions via hydrogen bonds, electrostatic attraction, and pore-filling were found to be the main mechanisms of adsorption of VOC in the biochar studied. The efficiency of biochar regeneration was assessed through five cycles of adsorption-desorption tests and was found to be between 88% and 96%. The incomplete desorption observed confirm the formation of likely permanent bonds and heel build-ups during the sorption process.

被原油污染的土地被认为对空气中的挥发性有机化合物 (VOC) 有重大贡献，对人类健康和对流层臭氧产生不利影响。在先进的土壤修复技术既不可用也不可行的情况下，用于控制有害排放的土壤覆盖系统是关键的工程解决方案。对生物炭中单一 VOC 种类的吸附研究显示出作为潜在封盖材料的有希望的结果；然而，目前对混合气体系统和 VOCs 在生物炭上的多组分吸附的理解非常有限，这将代表更现实的原位条件。我们首次展示了混合 VOC 的竞争吸附研究结果，$℃$以麦秆和甘蔗渣为原料。包括丙酮、己烷、甲苯和对二甲苯在内的多组分 VOC 在生物炭中的吸附动力学基于使用定制实验室设置的广泛实验研究的结果进行研究。本研究中使用的两种生物炭在单独测试时都表现出对 VOC 化合物的高吸附能力 (51–110 mg/g)。对于多组分混合物，占据生物炭表面吸附位点的竞争导致每个物种的绝对吸附能力较低，然而，生物炭的整体吸附能力与在单一气体实验中观察到的大致相似（50-109毫克/克）。通过氢键、静电吸引、研究发现，在所研究的生物炭中吸附 VOC 的主要机制是孔隙填充和孔隙填充。通过五个循环的吸附-解吸测试评估了生物炭再生的效率，发现在 88% 到 96% 之间。观察到的不完全解吸证实了在吸附过程中可能形成的永久键和脚跟堆积。