Reaction Mechanism Study On The Non-biodegradable Wastewater Treatment Via Supercritical Water Baesd On ReaxFF

With the economic and industrial development going on, the wastewater discharge has been getting more and more, especially for the non-biodegradable wastewater which has brought much negative influences. As an innovative reaction media, supercritical water(SCW) has drawn people's attention, and many scientists start to do research about the non-biodegradable wastewater treatment using SCW method. So it is quite important to clarify the processes and mechanisms about the wastewater treatment in SCW. The present work has introduced ReaxFF to take some simulations about the SCW reactions on wastewater treatment using the model of DO25 and TNT.The results show that the aromatic ring opening contains three pathways based on the attacking group in supercritical water oxidation(SCWO), including the attack of OH radical, O2 and OH radical together with O2. After that, the structure will form a three-membered ring and then be degraded into small molecules such as H2 O, CO2, and N2. At low temperatures, the third pathway is common and at high temperatures the first two pathways are common. Furthermore, extending reaction time and DO25 molecule number can also improve N elements convert into N2 rather than carbonitride.The conclusions made by the simulations of TNT degradation in SCW systems are as follows. Four pathways are obtained in SCWO including(1) NO2?ONO,(2) R-NO2 bond breaking,(3) R-NO2 turning into R-NOOH(4) O2 interacting with TNT to embed into the aromatic ring, the first three pathways of which are also found in supercritical water gasification(SCWG). NOH is an important intermediate that connects the former and latter reactions. In SCWO the main product is N2 and in SCWG is NH3. Supercritical water partial oxidation(SCWPO) can combine the advantages of SCWO and SCWG.