Research, The Processing Of Polyethylene Glycol

With a widespread industrial and domestic use of PEGs, concern has been expressed regarding the fate of wastewater containing these polymers. The treatment of PEG model wastewater with chemical reagent and membrane separation was studied in this thesis.Experiments were carried out with the cross design to optimize the oxidation conditions of PEG-2000. Among the factors affecting the CODcr removal ratio, H2O2 dosage was the most important one, then came the initial pH, the influences of temperature and time were weaker. Next, the effects of the way of adding H2O2, H202 dosage and the initial concentration of PEG on the decomposition were investigated, the results showed that the decomposition was mainly controlled by the amount of H2O2, but not the initial concentration of H2O2. And the COD removal increased with the initial concentration of PEG.Based on the former experiments, nanofiltration was added in the process. A combined nanofiltration and Fenton's reagent process for the treatment of PEG model wastewater has been demonstrated. The results suggested that it got not only permeate discharged directly (the water recovery is40%), but also the concentrate which enhanced the efficiency of Fenton's reagent. While the combination of Fenton's reagent and nanofiltration could increase the partial oxidation effeciency of the process, simplify the design of reator, minish the reator's volume and ehance the reaction rate. And the caculation models of nanofiltration were proposed in the thesis as well, by which the relationship of perpeation volume and COD of feed water could be analyzed. At last, the decomposition mechanism of PEG-6000 under different oxidation conditions was studied, the results showed that the relationship of COD removal and the amounts of Fenton's reagent was linear, and the mass ratio of substance (molecular weight under 200) almost kept constant. The decomposition of PEG molecular weights from 200 to 10000 showed that a maximum in the reactivity was observed, while the reactivity of PEG-200 and PEG-300 was low.