Reaction Mechanism Study On The Refractory Organic Wastewater Treatment Via Supercritical Water Technology

In recent years,the problems in the field of environment and energy have been significantly focused.Along with the development of industries,the wastewater discharge is quite large.Wastewater from industries contains hazardous and persistent organic pollutants which are critically harmful to the environment and public health.Because the supercritical water technology can widely and effectively deal with various kinds of pollutants which are toxic and stable,many researchers worldwide have studied the supercritical water technology in the wastewater treatment.In this study,ReaxFF reactive dynamics simulations were performed to investigate the treatment of pharmaceutical wastewater and coking wastewater via supercritical water technology and PCN and BaP were chosen as model compounds.By tracing the evolution of PCN intermediates,migration routes of S and N during the SCWO process were obtained with H₂S and NO₂ produced as the end products.Simulation results showed that SCW and oxidant not only accelerated the degradation reaction by producing radicals and O₂ molecules,but also served as H source for H₂S as well as O source for CO₂ and NO₂.The combination of experiment and Reax FF MD simulations will contribute to optimize the experimental parameters and shed light on the design of SCWO reactorThe BaP molecules in supercritical water oxidation,supercritical water gasification and supercritical water partial oxidation systems have different degradation pathways.There are three routes for the generation of H₂ molecules,producing from H radical-rich is the main route and the maximum H₂ yield is obtained at oxygen ratio of 0.2.CO molecules are formed by the C-C bond breakage and C-O bond breakage in the reforming fragments.Due to the change of instantaneous concentration of H₂ and CO,there is a time delay between the generation reaction of fuel gas and the side reactions,which gives a possible way to increase fuel gas amount by designing applicable reactor and recovering the gas fuel in time.Finally,kinetic behaviors of coking wastewater have been analyzed.