Acceleration Of Double Chain Small Molecular Cation To Reactive Dyeing Of Silk

Silk is a natural protein fiber, known as "fiber queen". For a long time, dyeing silk mainly used direct dyes, acid dyes and neutral dyes. Dye uptake of dyes on silk is high, but soaping and rubbing fastness of the dyeing silk fabric is low. Activated dye is known as reactive dye. The active group of reactive dye molecules can combine with silk fiber by covalent bond. Reactive dyeing of silk has high rubbing and soaping fastness. But the fixation rate of reactive dyes on silk is low, and the dyeing process requires a lot of neutral salt to accelerate. So reactive dyeing of silk would produce a large number of dyeing wastewater which contains high chroma and salinity. Load of wastewater treatment is tremendous.In order to improve the fixation rate of reactive dyeing of silk and reduce the dosage of neutral salt, double chain small molecular cation was design synthesis and used as accelerant for reactive dyeing of silk in this dissertation. This dissertation includes design synthesis of double chain small molecule cation, such as octyl butyl dimethyl ammonium bromide, octyl hexyl dimethyl ammonium bromide and dioctyl dimethyl ammonium bromide. H NMR was used to characterize the structure of the small molecular cation. The accelerating effect and dyeing fastness of six reactive dyes on dyeing silk was studied with double chain small molecular cation as accelerant. With small molecular cation as accelerant, the adsorption rate curve of reactive dyes on silk was analyzed. In order to analyze adsorption kinetics and thermodynamic, the quasi-first and quasi-second order adsorption kinetics simulation equations, Arrhenius formula and Eyring formula were used to fit experimental data in the process of reactive dyes on dyeing silk. We also studied the accelerating mechanism of small molecular cation on silk with reactive dyes. UV-vis spectropHotometer, nano particle sizer and micro electropHoresis apparatus were used to study the interaction between double chain small molecule cation and reactive dyes and the interaction between double chain small molecule cation and silk. The results showed that:(1) Double chain small molecular cation was design and synthesis. The structure of double chain small molecular cation was characterized by’H NMR. The result was in keeping with theoretical design.(2) With double chain small molecular cation as accelerant, the accelerating effect of reactive dyes on silk was related to the hydrocarbon chain length of double chain small molecular cation. When the carbon atom number of the longest hydrocarbon chain was eight, the accelerating effect of reactive dyes on silk increased with the increase of the carbon atom number of long hydrocarbon chain.(3) Compared with sodium sulfate, concentration of double chain small molecular cation at3-6g/L could reach the accelerating effect of concentration of sodium sulfate at60g/L. The dosage of accelerant decreased10-20times. When concentration of double chain small molecular cation was2-6g/L, dye uptake and fixation rate of most reactive dyes on dyeing silk could respectively reach95%-99%and90%-98%. Double chain small molecular cation was an effective accelerant.(4) With octyl butyl dimethyl ammonium bromide, octyl hexyl dimethyl ammonium bromide and dioctyl dimethyl ammonium bromide as accelerants, rubbing and soaping fastness of reactive dyeing silk were4or above4degree. The dyeing fastness of dyeing silk with double chain small molecular cation as accelerant was comparable to sodium sulfate as accelerant. All of them met EU requirement of4or above4degree.(5) With traditional sodium sulfate and double chain small molecular cation as accelerants, dye initial adsorption rate increased with the increase of temperature. At the same temperature, compared with sodium sulfate, dye initial adsorption rate of small molecular cation was higher. Small molecular cation as accelerant could achieve adsorption equilibrium faster, and obtain a higher dye adsorption equilibrium capacity. When double chain small molecular cation was added by several times, adsorption rate of dye on silk decreased. Silk was dyeing even.(6) With double chain small molecular cation and sodium sulfate as accelerants, the adsorption process of reactive dye on silk fitted quasi-second order kinetics equation. When concentration of sodium sulfate was60g/L, concentration of octyl butyl dimethyl ammonium bromide was1.8-2g/L, concentration of octyl hexyl dimethyl ammonium bromide was1.2-1.8g/L and concentration of dioctyl dimethyl ammonium bromide was 0.6-1.2g/L, the gibbs free energy of small molecular cation as accelerant was lower than that of sodium sulfate as accelerant in the adsorption process of reactive dyeing silk. The colourability of reactive dyes was improved.(7) The accelerating mechanism of double chain small molecular cation to reactive dyeing of silk was obtained as follows:double chain small molecular cation could neutralize part charge of dye molecules and make reactive dyes assembled in water solution, so the water solubility of reactive dyes was reduced and the colourability of reactive dyes was promoted; double chain small molecular cation could neutralize effectively carboxyl of silk fibroin macromolecules to improve zeta potential of silk surface, reducing the repulsion between silk and reactive dyes and promoting the colourability of reactive dyes; when the concentration of double chain small molecular cation was high, most negative charge of silk surface was neutralized, zeta potential of silk surface changed to positive charge for the amino cation of silk, so silk could adsorb reactive dye molecules effectively, realizing high-efficient acceleration of double chain small molecular cation.Acceleration of double chain small molecular cation to reactive dyeing of silk had a good application prospect, because the dosage of small molecular cation was low, fixation rate of reactive dye was high and double chain small molecular cation as accelerant could reduce the load of dye wastewater treatment greatly.