Research And Application Of New Dyeing Technology Of Polyacrylonitrile Fiber For Deep Water-saving And Pollution-reduction

Repeated washing processes are needed for the dyeing polyacrylonitrile fiber with cationic dyes to guarantee the color and color fastness of the dyed samples.That leads to not only the water consumption but also the wastewater emission are large.Meanwhile,it’s hard to degrade for the dyes and auxiliaries with cationic group,and the municipal sewage treatment is high in the cost.In order to solve the problems above,a new dyeing technique of polyacrylonitrile fiber,Polyacrylonitrile Fiber In-situ Mineralization Dyeing,is developed.The in-situ mineralization coupling reagents for polyacrylonitrile fiber are directly added into the bath after the dyeing of polyacrylonitrile fiber with cationic dyes.In result,the residual dyes and auxiliaries are mineralized and decomposed in its original producing position.On the basis of a good quality of the dyeing fiber without washing,it can be achieved that water-using and emission are reduced.At the first,the dyeing dynamics and thermodynamics behaviours of the polyacrylonitrile fiber with cationic dyes were studied,and the dyeing in-situ was discussed.The results show that the dyeing process of polyacrylonitrile fiber with cationic dyes followed the pseudo second-order kinetic model,and the adsorption isotherm type is the Langmuir-type.At higher temperature,there are advantages of initial adsorption rate and rapid exhaustion rate and.The equilibrium adsorption capacity and dyeing saturation value are large.It’s the brevity of half-dyeing time and the dye diffusion is full enough.The high utilization of dye can reduce the burden of mineralization and have positive significance to the effect of dyeing and mineralization.Secondly,the optimum process of the in-situ mineralization of polyacrylonitrile fiber is determined with the single factor test.When the amount of cationic dye is X%（owf）,the amount of XBQ is 0.2X%（owf）and the amount of XYQ is 1.5X%（owf）;the system was treated at 70℃for 30min.By contrast,the color accuracy and the color fastness of the samples dyed in-situ mineralization are the same with those dyed by conventional process,and the strength is better than the samples dyed by conventional process;in addition,the water saving radio was up to 80%in new technology,effluent chrom and COD_Crr of the effluent are respectively reduced by more than 98%and 65%.The in-situ mineralization technology achieved the significant effect on water-saving and pollution-reduction.Finally,the results of the chroma,COD_Cr,UV-VIS of the effluents and the SEM,XRD,IR of the dyed polyacrylonitrile fibers show that the in-situ mineralization coupling reagents can destroy the chromogenic group and conjugated structure of the dyes,and the dyes and auxiliaries can be degraded.The chemical composition of the samples dyed in-situ mineralization is unchanged,the apparent morphology and the quasi-crystallinity of the samples are slightly better than those dyed by conventional process.