Research Of Synthesis And Application Of Azo Dyes Based On Waste Polyester

With the advancement and development of society, excellent physical and chemicalproperties of polyester, polyester has been widely used in various fields. With the extensiveapplication of the polyester, large number of waste polyester will be produced, if mishandledthe waste polyester, not only pollution of the environment but also causes the waste of energy.Chemical recycling of waste polyester can be recycled, the way of chemical recycling is morescientific, glycolysis can get the degradation product BHET which can be used in themanufacture of polyester, and has achieved continuous production, is considered to bepractical value recovery method. More than half of polyester products are used in the textileindustry which in the form of polyester fiber, textile, therefore, using the degradation productsBHET and TPA to synthetize the azo dyes.This subject adopted methods of glycolysis to get the degradation product BHET,discussed the influence of reaction time, the amount of catalyst, the amount of ethylene glycolon degradation rate. According to the characteristics of BHET, used sodium hydroxide tohydrolyze BHET, and then obtained the TPA. Used BHET to synthetize the diazonium salt bythe nitration, reduction and diazo reaction, used this diazonium salt react withN,N-dimethylaniline and3-Methyl-1-(4-sulfophenyl)-5-pyrazolone to form Azo dyeⅠandAzo dyeⅡrespectively. Then used TPA to synthetize the diazonium salt by the nitration,reduction and diazo reaction, used this diazonium salt react with N,N-dimethylaniline to formAzo dye Ⅲ.Azo dyeⅠ, Ⅱ, Ⅲ were used for dyeing nylon and polyester fibers, and to discuss theeffects of pH value of dye liquor on dyeing rate and L*, a*, b*value respectively, then canconclude that maximum dyeing of rate azo dyeⅠ, Ⅱ, Ⅲ that dyed nylon were71.4%,75.4%,84.7%, that maximum dyeing rate of azo dyeⅠ, Ⅱ, Ⅲ that dyed polyester fibers were86.1%,57.0%,39.8%, and ultimately found azo dye Ⅰ was suitable for dyeing polyester fiber, azodye Ⅲ was suitable for dyeing nylon in low pH value.At the same time, a preliminary discussion on the influence of reaction time, the amount ofcatalyst, the amount of ethylene glycol on degradation rate in the process of degradation ofwaste polyester to synthetize BHET; the influence of reaction time, reaction temperature,mass ratio of concentrated sulfuric acid nitric acid on the yield of nitration product in theprocess of nitration，preliminarily concluded that optimal technological condition for theglycolysis was that reaction time was1h, m(PET):m(EG) was1:3, the amount of catalyst was0.3%; optimal technological condition for the nitration was that reaction temperature was70℃, reaction time was8h, m(nitric acid):m(sulfuric acid) was1:7.In summary, the BHET and TPA which were made from waste polyester by the way ofglycolysis were used to synthetized three different azo dyes that used for dyeing nylon andpolyester fiber, the maximum dyeing rate can up to84.7%,86.1%. By using the method ofrecycling waste polyester can not only reduce the waste of resources, accord with therequirements of energy conservation, reduce environmental pollution, but also can be a goodrecycled well in the textile industry, can achieve industry recycling of textile industry, and the recycling of resources.