Research On Treatment Of Two Kinds Of Chlorinated Organic Phosphate Simulated Wastewater By UV/H₂O₂

Organophosphate esters (OPES) mainly added and mixed into the poymer rather than formed a chemical bound with the polymer, so it increases the probability of OPEs into the surrounding environment. Some of OPEs are considered to be toxic to organisms, such as TCEP has carcinogenicity, nerve toxicity and teratogenicity, TDCP and TCPP also display certain carcinogenicity, and we can’t ignore the possible toxity of OPEs. As a class of emerging pollutants, conventional sewage treatment technology was hardly useful to chlorinated OPEs, so it’s important to find a new way to treat this kind of wastewater.In this research, two commonly used chlorinated OPEs has been chosen for model wastewater, Tris (2-chloroethyl) phosphate (TCEP) and Tris (1,3-dichloro-2-propy) phosphate (TDCP), which were treated by UV/H2O2. This thesis included three parts as follows:(1) The Optimal Conditions of reactive TCEP by UV/H2O2Different influence factors in the process of UV/H2O2which influence the degradative effect of reactive TCEP solution were studied. The results indicated that the removal of total organic carbon (TOC) and mineralization rate were obviously higher than they acted respectively. For143mg/L of TCEP, in ambient temperature, on the best reaction condition of that the initial concentration of H2O2was5mmol/L, light intensity of ultraviolet lamp was94.5x100|xW/cm2, pH value was7.0, and reaction time was60min, the removal of TOC, and the yield rates of Cl’and PO43" reached up to86%,94%and97%, respectively.(2) The Optimal Conditions of reactive TDCP by UV/H2O2The resulet indicated that for10mg/L of TDCP model solution, the optimized experimental conditions were as follows:the initial concentration of H2O2was5mmol/L, light intensity of ultraviolet lamp was94.5x100μW/cm2, pH value of model solution was7.0, and reaction time was60min. The total organic carbon (TOC) removal rates and the yield rates of Cl-and PO43-reached up to93.69%99.25%and99.21%, respectively. The removal rates of TOCand mineralization by UV/H2O2were significantly superior to those obtained from UV or H2O2alone employed. The light intensity of ultraviolet lamp was the most important parameter in degration of TDCP.(3) The mechanism of UV/H2O2was investigated in the experiments.The degradation efficiency of TCEP decreased when t-butanol was added into UV/H2O2system. Theses results showed that hydroxyl radicals played an important role and was supposed to be reactive species in the present UV/H2O2system. The produced hydroxyl radicals attacked TCEP, TCEP was degraded into monochloroacetic acid, monochloroacealdehyde, formic acid, acetic acid and some small molecular organics, PO43-ions were released at this time. The degradation process of TCEP obeyed the pseudofirst order kinetic reaction. Under the optimized parameters,143mg/L of TCEP spiked into the real wastewater was treated. The results showed that the total organic carbon removal rates and the yield rates of Cl-and PO43-reached up to79%,72%, and71%, respectively, within60min reaction. The treatment efficiency decreased compared with that from distilled water. This discrepancy may be ascribed to the following possibilities. The effect of some radical scavengers in the real wastewater decreased the concentration of hydroxyl radicals; it was also possible that some of TCEP may combine with dissolved organic matter, which could result in the less concentration of freely dissolved TCEP, exhibiting with lower degradation rate.