Novel design and dynamic control of coal pyrolysis wastewater treatment process

Copper-based Ruddlesden-Popper perovskite oxides activated hydrogen peroxide for coal pyrolysis wastewater (CPW) degradation: Performance and mechanism

Coal pyrolysis wastewater (CPW) contained all kinds of toxic and harmful components, which would seriously threaten the natural environment and human health. However, the traditional advanced oxidation processes frequently failed to remove phenolic substances. An A₂BO₄-type perovskite (La₂CuO₄) was successfully synthesized through sol-gel process and first applied in the treatment of CPW. More than 90% of 3, 5-dimethylphenol (DMP) was removed within 200 min at neutral conditions. Moreover, La₂CuO₄ also displayed excellent catalytic activity and stability in the actual CPW treatment process. Results demonstrated that DMP was removed through the attack of ∙OH, ∙O₂^- and ¹O₂ in La₂CuO₄/H₂O₂ system. The La₂CuO₄ were more favorable for H₂O₂ activation and have a lower adsorption energy than LaFeO₃. XPS of fresh and spent La₂CuO₄ illustrated that the decomposition of hydrogen peroxide (H₂O₂) was mainly due to the redox cycle between surface copper and oxygen species. Moreover, the possible degradation pathway of DMP was deduced by identifying degradation products and analyzing density functional theory (DFT) calculations. This research provided a novel strategy for the development of perovskite-based catalytic materials on the treatment of practical CPW.

Optimal design of a multi-dimensional validated synergistic extraction process for the treatment of atmosphere-vacuum distillation wastewater

The wastewater discharged from atmosphere-vacuum distillation of oil refining process contains a high concentration of phenolic compounds, which are toxic and not eco-friendly. Direct discharge of the untreated wastewater will have an adverse impact on the surrounding environment. This paper proposes a multi-dimensional synergistic extraction solution to realize the effective disposal of atmosphere-vacuum distillation wastewater. Firstly, extraction experiments are conducted to select the optimal extractant. Secondly, the microscopic mechanism of separating phenolic compounds from wastewater with synergistic extractant of methyl isobutyl ketone and n-pentanol is investigated by molecular dynamics simulation. Finally, the synergistic extraction process is modeled and optimized based on above multi-dimensional analyses. The optimization is performed through sensitivity analysis from three aspects: operating parameters, synergistic extractant cycling, and waste heat recovery. A control scheme is then designed to maintain the smooth operation of synergistic extraction process. Feed disturbances are specifically added to test the anti-interference capability of the control scheme. With the novel treatment process proposed in this paper, the removal rate of phenolic compounds from atmosphere-vacuum distillation wastewater reaches 93.02%.

A Fault Identification Method in Distillation Process Based on Dynamic Mechanism Analysis and Signed Directed Graph

Due to the complexity of materials and energy cycles, the distillation system has numerous working conditions difficult to troubleshoot in time. To address the problem, a novel DMA-SDG fault identification method that combines dynamic mechanism analysis based on process simulation and signed directed graph is proposed for the distillation process. Firstly, dynamic simulation is employed to build a mechanism model to provide the potential relationships between variables. Secondly, sensitivity analysis and dynamic mechanism analysis in process simulation are introduced to the SDG model to improve the completeness of this model based on expert knowledge. Finally, a quantitative analysis based on complex network theory is used to select the most important nodes in SDG model for identifying the severe malfunctions. The application of DMA-SDG method in a benzene-toluene-xylene (BTX) hydrogenation prefractionation system shows sound fault identification performance.