Shuo Zhang,Shihao Zhang,Shuran Li,Rongwei Ma,Anyu Wang,Zhen Liu,Keping Yan
In this study, the planetary ball milling with CaO addition was used to remediate lindane-contaminated soil. Based on Hertzian theory, a mathematical model was proposed to simulate the trajectory of grinding ball and the local energy transfer during a planetary operation at the disk rotation velocities of 150–250 rpm. Besides, the influence of different parameters on lindane removal in soil was investigated, whose results showed that disk rotation velocity and reagent-to-soil ratio had a positive effect, while soil moisture, initial concentration of lindane , and mass of polluted soil demonstrated a negative influence. The mechanochemical method exhibited a higher degradation performance at 3 wt% CaO addition, and a disk rotation velocity of 250 rpm. Active species generated by ball collisions in the presence of CaO, especially superoxide (·O 2 − ) demonstrated a significant role in participating in the lindane conversion. In combination with GCMS and XPS analysis , the proposed model provides insight into mechanochemical remediation process from physical and chemical perspectives, which mainly includes four main steps: mixing, inducing, chemical reaction, and structure destruction.
Many works have focused on the reactivity and valence transition of Fe-based oxygen carriers in chemical looping partial oxidation reforming process. However, the reforming performance and impacts of operating factors are unclear with the co-feeding of CaO being CO 2 carrier to realize simultaneous CO 2 capture and utilization. In this work, thermodynamic equilibrium calculation, reactivity test and material characterization are carried out to optimize the process characteristics. The impacts of feeding conditions (Fe/Al weight ratio, methane amount, Ca/Fe mole ratio and packing manner) on the reforming reactivity are obtained to reveal the interaction between CaO and Fe 2 O 3 . The gas product distribution indicates that the carbon deposition and oxidation degree is closely related to CH 4 amount. The spatial configuration between CaCO 3 and Fe 2 O 3 reforming is essential to obtain the desirable reforming products. The difference of FeO existence on the theoretical and experimental phase components illustrates that reaction degree is affected by the reduction agent amount. By comparing the methane temperature-programmed reaction of CaCO 3 , Fe 2 O 3 and their mixture, it is suggested that the existence of CaCO 3 is beneficial for accelerating iron-based methane reforming. This study provides a way to improve reaction degree and optimize process characteristic for chemical looping reforming process.
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