Preparation Of Organic Polymer/metal Oxide Composite Fiber And Study On Its Decolorizing Dye Performance

Poly(butyl methacrylate-co-hydroxyethyl methacrylate)and poly(butyl acrylate-co-hydroxyethyl methacrylate)were firstly synthesized via solution polymerization,and their blend solution prepared at a volume ratio of 85:15 was then used as spinning dope to prepare hollow fiber through wet spinning.At a certain temperature,hollow fiber was firstly hydrolyzed in the aqueous solution of sulphuric acid,and the hydrolyzed fiber was then reacted with the aqueous solution of potassium permanganate to immobilize manganese oxide generated in-situ onto hollow fiber through complexation.At last,a composite hollow fiber of poly(meth)acrylate and manganese oxide,which could be used to decolorize the aqueous solution of cation blue(CB),was prepared.The research results showed that the composite hollow fiber exhibited excellent capability to decolorize CB,and the time that was needed to decolorize 95%of CB from lOmL of its solution with the concentration of 20mg/L was less than 30min.O2·-that was produced during decolorization could provide manganese oxide with the function to keep Mn valence unchanged,as a result,the composite hollow fiber could be used up to 5 cycles without any loss in CB decolorization efficiency,showing good reusability.The composite hollow fiber could oxidatively destroy the double bond of C and N in CB molecule;thus the conjugated structure of CB molecule was destroyed;consequently,the color of CB solution faded.In order to reduce the influence of post-treatment on the overall structure of hollow fiber and to improve the mechanical properties of hollow fiber,the process of internal coating was adopted to immobilize in-situ generated manganese oxide onto the inside of hollow fiber through complexation.The immobilization of manganese oxide could remarkably enhance the capability of poly(meth)acrylate hollow fiber to decolorize water containing methylene blue(MB)when the water flowed into hollow fiber.The effect of blend solution composition,hydrolysis time and oxidation time on MB decolorization was studied,and some relatively good internal coating parameters were confirmed.The volume ratio of two polymer solutions was 85:15;acid hydrolysis time was lh,and potassium permanganate oxidation time was 2h.Under these parameters,the hollow fiber with a internal coating of manganese oxide was prepared,and then used to fade the color of MB aqueous solution.The results showed that the decolorization efficiency of MB caused by the hollow fiber without the coating of manganese oxide was only 10%;however,when the aqueous solution of MB flowed into the hollow fiber with the coating of manganese oxide MB decolorization efficiency increased to 78.7%,and even though the hollow fiber was used for several times MB decolorization efficiency was still higher than 10%.The process of internal coating can load manganese oxide onto the inner surface of the hollow fiber and even its inside.However,it is very difficult to spin poly(meth)acrylate into hollow fiber with a lot of connected holes,as a result,the obtained hollow fiber can only use its inner surface to decolorize dye wastewater,but can not use its side wall.In order to transform hollow fiber into hollow fiber membrane,polyacrylonitrile was used to replace poly(meth)acrylate to prepare hollow fiber in which a lot of connected holes were formed during wet spinning,and the process of internal coating was also used to decorate the porogen-free polyacrylonitrile hollow fiber membrane with in-situ generated well-distributed Fe/Mn oxide,and the prepared composite hollow fiber membrane was used to decolorize MB aqueous solution.The results showed that MB decolorization efficiency could reach 97.4%when MB aqueous solution containing H2O2 passed through the side wall of hollow fiber membrane,and MB decolorization efficiency still reached 92.5%after it was repeatedly used for 15 times.On the contrary,when PAN hollow fiber membrane that did not have Fe/Mn oxide was adopted,MB decolorization efficiency greatly decreased from 94.9%to 7.9%with repeated time.Finally,the mechanism by which the composite hollow fiber membrane of PAN and Fe/Mn oxide could cause the decolorization of MB aqeuous solution was proposed by analyzing MB decolorization induced by modified and unmodified hollow fiber membranes,the change of total organic carbon and the spectra of UV-Vis.The composite hollow fiber membrane of PAN and Fe/Mn oxide could be used as heterogeneous Fenton catalytic reactor to catalyze H2O2 to decompose into reactive oxygen species,which could oxidize MB into small molecules,CO2 and H2O;thus the color of MB aqueous solution disappeared.