| In this dissertation,butyl methacrylate(BMA),butyl acrylate(BA)and hydroxyl ethyl methacrylate(HEMA)were used as monomers,benzoyl peroxide(BPO)was used as initiator,and N,N-dimethyl formamide(DMF)was used as solvent,the solution of the copolymer of BMA and HEMA(P(BMA-co-HEMA))and the solution of the copolymer of BA and HEMA(P(BA-co-HEMA))were synthesized via solution polymerization.A blend solution was prepared by mixing the solution of P(BMA-co-HEMA)with the solution of P(BA-co-HEMA),and their volume ratio was equal to 85:15.The hollow fiber was prepared by using the blend solution as spinning solution and distilled water as coagulation medium through wet spinning.Under the heating condition,the hollow fiber was immersed in potassium permanganate solution with different pH value to make manganese oxides with different morphologies loaded on its inner and outer surfaces.The morphology,crystallization behaviors and thermal properties were analyzed,along with the catalytic performance.When lOmL CB aqueous solution with the concentration of 20mg/L was used as original pollutant,and 0.5mL H2O2 was added into the original pollutant,the composite hollow fiber prepared in potassium permanganate solution with a pH of 14.4 had better catalytic activity for the decomposition of cationic blue.The removal efficiency of cationic blue at 90min was up to 94.4%.When it was used for the second or third time,the removal efficiency of cationic blue at 90min were 79.3%or 57.2%.The above composite hollow fiber showed relatively weak catalytic activity.A long time was needed to achieve an expected removal efficiency,and the composite hollow fiber exhibited very poor reusability.In order to make up for the above defects,the hollow fiber was deeply treated by using a two-step process:hydrolysis in sodium hydroxide solution and oxidation in neutral potassium permanganate solution in the dissertation.A novel composite hollow fiber with strong catalytic activity and good reusability was prepared via the above procedures.Its morphology,composition,chemical groups,crystallization behaviors and thermal properties were analyzed,along with the catalytic performance.The results showed that compared with manganese oxides and hollow fiber,it exhibited a higher catalytic activity due to the synergistic effect of manganese oxide and fiber matrix and the response of fiber matrix to water stimulus.When 0.024g composite hollow fiber was added in 10mL aqueous solution of cation blue with the concentration of 20mg/L,the complete removal of cation blue could be achieved within 14min in the presence of 0.5mL H2O2.When 0.072g composite hollow fiber was added in lOmL aqueous solution of cation blue with the concentration of 20mg/L,the composite hollow fiber could be repeatedly used up to 10 cycles without any significant loss in its catalytic activity in the presence of 0.05mL H2O2.For each cycle,the time that was needed for removing 90%of cation blue from its solution was less than 6min,and its removal efficiency at 10min was up to 95%.The identification results of oxidative species showed that the composite hollow fiber could accelerate the transformation of H2O2 into HO·,HOO·,O2·-and 1O2 in the presence of H2O.These oxidative species oxidized cation blue to cause its rapid removal... |
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