Lei Wu,Hongyan Wu,Qiusi Wen,Jun Zhou,Ahmed M. Aljuwayie,Poh Wai Chia,Gan Ye,Qiuli Zhang,Rock Keey Liew,Su Shiung Lam
Thermal desorption technology at low temperatures has been extensively researched. However, the challenge remains in maintaining soil ecological function while effectively removing PAHs from contaminated soil using this method. Based on the gas hammer fragmentation concept, this study presents the strategy of gas stripping (steam extraction) coupled with microwave remediation. A multifunctional bluecoke-based modifier (MnO 2 /KHCO 3 @BC) was prepared followed by an investigation on the removal effect, soil characteristics and remediation mechanism of MnO 2 /KHCO 3 @BC-assisted microwave remediation of pyrene (PAHs model) contaminated soil. The research findings indicate that MnO 2 /KHCO 3 @BC is more effective in generating oxygen vacancies, facilitating surface electron transfer , and enhancing the oxidation effect of ROS on pyrene compared to KHCO 3 @BC and MnO 2 @BC. Despite having slightly inferior electromagnetic properties to BC, MnO 2 /KHCO 3 @BC could achieve a microwave remediation temperature of approximately 300 °C under optimal experimental conditions. MnO 2 /KHCO 3 @BC demonstrated remarkable pyrene removal efficiency with a maximum removal rate of 98.34%, making it an ideal candidate for pyrene remediation. Moreover, the remediated soil exhibited a weakly acidic nature, with a significant decrease in particle size and a substantial increase in potassium content. The study also highlighted a novel synergistic mechanism of ''microwave heating - gas stripping - oxidation,'' which can efficiently remove most of the pyrene adsorbed inside and outside of soil particles and degrade it into low-toxic and small-molecule organic matter, CO 2 , and H 2 O. Overall, the findings of this study could hold potential significance for upcoming endeavours concerning polluted industrial areas.
Lei Wu,Zixuan Hu,Yuan Gao,Changsheng Yue,Changbo Liu,Rock Keey Liew,Tiantian Liu,Jun Zhou
Microwave (MW) remediation of organics-contaminated soil technology offers the advantages of high efficiency and minimal damage, representing a new approach of soil thermal remediation. However, soil, being a weak MW-absorbing medium, struggles to convert MW energy into thermal energy, thus failing to attain the necessary temperature for thermal remediation. This paper prepared two new bluecoke (BC)-based modifiers (KHCO 3 @BC and KHCO 3 /MnO 2 @BC) to address temperature problem of MW remediation, as well as enhance soil quality. Their composition, structure and electromagnetic properties were analyzed to investigate their role in assisting with the MW remediation of an artificially crude oil-contaminated soil were investigated. Additionally, the industrial feasibility of MW remediation was addressed for the first time. The results showed that the KHCO 3 and MnO 2 particles in the two modifiers were covered on the BC surface and exhibited local agglomeration. Their carbon crystalline grain size increased, and the electromagnetic properties were weaker than those of the BC. Following 10 min of MW remediation assisted by KBC or KMnBC, the remediation temperatures exceeded 300 °C, with the removal rates of PHs reaching 76.16% and 88.31%, respectively. The organic matter content, soil potassium and mechanical fraction of the remediated soil were improved, but soil acidification still needed to be further addressed. The industrial application analysis indicated that the technical process and techno-economics of MW remediation of crude oil-contaminated soil were feasible, suggesting significant potential for the large-scale industrial application.
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