Study On The Preparation And Catalytic Performance Of Quinonyl Fiber Cloth

Azo dyes are widely used by printing and dyeing industries, because of their bright colour, high fixation rate and good color fastness. But with the increase of the applications of azo dyes, the produced wastewater containing azo dyes causes great threat on the ecological environment. Among the treatment methods for the dyes removed from wastewater, the one of the effective methods is the anaerobic-aerobic bio-treatment. The rate-limiting step of the method is an anaerobic treatment process. Recent studies showed that redox mediators could effectively accelerate the process. However, the continuous addition of redox mediators such as quinone compounds will increase the running cost and cause the secondary pollutions.The main purpose of this dissertation is to explore a novel method for quinone immobilization using the industrial polyester filter cloth as a carrier, which possess the advantages of great stability, excellent resistance against acids, weak base. The redox mediator anthraquinone-2-sulfonic acid sodium (AQS) was covalently immobilized on the polyester filter cloth (AQS-PET cloth) using chemical method, and the reaction conditions were optimized. Fourier transform infrared spectrometer (FTIR), scanning electron microscope (SEM) and elemental analyzer were used to characterize the surface texture of the quinonyl fiber cloth. Moreover, its catalytic performance on the bio-decolorization of azo dyes was investigated.The preparation of AQS-PET cloth includes two steps:amination and sulfonation reactions. Our results showed that the optimal amination time was9h using the diethylenetriamine (DETA) as an amination reagent, and the optimal sulfonation reaction time were1h using the anthraquinone-2-sulfonyl chloride (ASC) prepared from AQS as the sulphonation reagent. Under these conditions, the concentration of immobilized quinone was12.5μmol·g-1by the elemental analyzer. The FTIR spectra also demonstrated that quinone was successfully immobilized on the polyester filter cloth. SEM showed that there were different levels of local damage on the aminated polyester filter cloth and AQS-PET cloth. But the obtained AQS-PET cloth under the above conditions did not affect its practical application as a biological carrier.The catalytic performance of AQS-PET cloth on the decolorization of azo dyes by Shewanella alga was studied. The results showed that AQS-PET cloth could obviously accelerate the decolorization rates of azo dyes. For acid red3R, Reactive brilliant red X-3B, amaranth, acid red GR and Metanil yellow, their decolorization rates in the presence of AQS-PET cloth were increased by3.4,2.2,4.2,2.2, and5.4-fold, respectively, compared with those lacking AQS-PET cloth. In the biological decolorization system of acid red3R, with the increase of the immobilized quinone concentrations ranging from0.025mM to0.1mM, the first-order kinetic constants obviously increased from0.39h-1to1.14h-1. After8repeated usage, the immobilized AQS-mediated decolorization rate of acid red3R remained87.3%of their original value.The process of immobilized quinone-mediated decolorization of azo dyes by Shewanella alga was preliminary studied in this paper. Research results showed that the decolorization rate of azo dye and the immobilized quinone-mediated decolorization rate of azo dye were increased9.68-fold and3.39-fold by the addition of the supernatant from the immobilized quinone-mediated decolorization system, respectively. Preliminary analysis indicated that Shewanella alga could produce some kind of redox mediators during the immobilized quinone mediated decolorization process of azo dyes. Fluorescence spectrophotometer analysis of the supernatant showed that the redox mediators produced by Shewanella alga might be Riboflavin.