Study On Preparation Of PET@MgFe₂O₄ And Their Treatment Of Dyeing Wastewater

Water shortage is the problem in our country, at the same time we are also facing the problem of serious water pollution. A large number of industrial waste water cost much more for utilization of water resources and has been a great threat to the urban water and people’s health. Dyeing wastewater is one of the industrial wastewater whose emissions are large. It is one of the industrial wastewater difficult to deal with because of the complex composition, color depth, large variation of water quality and poor biochemical degradability. Study on non-polluted and efficient treatment methods of dyeing wastewaterhas positive significance on sustainable utilization of water resources.There are shortcomings on the traditional treatment processes of dyeing wastewater, such as physical adsorption cannot degraded the pollutants, chemical precipitation and biological degradation produce a large amount of sludge and cost much time. This research is based on the catalytic oxidation method which has attracted much attention in recent years, references tomany research results, prepares the catalyst magneticmagnesium ferrite materials (MgFe2O4) and the polyester immobilized material (PET@ MgFe2O4), combines with the Fenton theory, simulates wastewater with the Reactive Brilliant Red X-3B, and treats the model wastewater with catalyst and H2O2 under the microwave irradiation. This paper discussed the preparation condition, structure, decolorization performance and the reusability of the catalyst and its optimal conditions when treating the model wastewater with H2O2 under the microwave irradiation.The results we obtain from this study show as follows:(1) Magnetic MgFe2O4 is prepared with ferrous chloride (FeCl2 · 4H2O)and magnesium chloride(MgCl2 · 6H2O) by chemical coprecipitation and roasting. When the ration of the magnesium and iron is 1.5:1 and the roasting temperature is 400 ℃, the particle’s average size is of 144.2nm and MgFe2O4 is of good decolorization performance:Its adsorption decolorization rate after 180 minutes is 42.17% and its catalytic oxidation degradation decolorization rate is 88.6%, when the model wastewater (100mg/L100mL) was treated with 0.05g MgFe2O4.(2) PET@ MgFe2O4 is prepared with MgFe2O4 and the polyester which is modified on surface by alkali, the MgFe2O4 is loaded on the surface of the modified polyester layer-by-layer. The tensile strength of PET@MgFe2O4 is influenced by the surface treatment of polyester fiber and the layer number of loading and the loading temperature. The amount of load increases with the increase of the layer number of assembly and the decolorization performance of model wastewater treated with PET@ MgFe2O4 is good.(3) The main factors influencing the decolorization rate is the catalyst quality, H2O2 dosage, microwave power, initial pH value and reaction time. During treating the model wastewater, MgFe2O4 and PET@ MgFe2O4 reacted as adsorbents and catalyst. MgFe2O4 adsorbed the microwave and formed the high temperature active site on its surface, at the same time dye was adsorbed there and the H2O2 was catalytic to decomposition there,OH radicals which are the decomposition products can degrade the dye molecule quickly so that the model wastewater was decolorized fast and efficiently.(4) The optimal conditions of the wastewater treatment process were obtained by the response surface methodology. Treatment of model wastewater (100mg/L,100mL) with MgFe2O4and H2O2under the microwave irradiation:qualityof MgFe2O4is 0.45 g, H2O2 dosage is of 0.62 mL (six over ten thousand), microwave power is 281.58 W, the response time is 7.86 minutes, the decolorization rate can reach to 99.87%. Treatment of model wastewater (50mg/L,100mL) with PET@MgFe2O4 and H2O2 under the microwave irradiation:load later of PET@MgFe2O4 is 12.07(2*2cm), initial pH is 1.00, H2O2 dosage is 49.97 ‰, microwave power is 298.30 W, the response time is30 minutes, the decolorization rate can reach to 94.93%.For that MgFe2O4and PET@MgFe2O4can be prepared simply, their decolorization performances are excellent, they can be reused and the treatment process has no second pollutants, and tested by experiments we know that they can be used for decolorizing the wastewater which come from printing and dyeing factory, this method for treating dyeing wastewater with catalyst and H2O2 under the microwave irradiation is efficient and green.