Dyeing properties of madder pigment on bio-based polyamide 56
Objective Madder pigment is a natural dye of bright red color with stable performance.Bio-based polyamide 56(PA56)is an environment-friendly and excellent bio-based polyamide material.In this research,madder pigment was adopted to dye PA56 fabrics,the dyeing process was optimized,and the dyeing kinetic mechanism was studied.The research results provide a theoretical basis for the application of madder natural dyes to bio-based PA56 fabrics.Furthermore,applying natural dyes to bio-based materials would meet the requirements of circular economy and low-carbon sustainable development.Method In order to study the dyeing performance of madder on PA56 fabric,the parameters including pH,dyeing time,dyeing temperature and mass fraction of Peregal O were explored to find the optimal conditions.Through K/S value and color characteristics,the influences of mordants and mordant treatment processes were studied.The optimal conditions obtained were subsequently adopted to study the kinetic of madder pigment dyeing.Pseudo first-order and pseudo second-order kinetic models were adopted to examine the mechanism of the adsorption process.Kinetic parameters of madder pigment dyeing on PA56 fiber with different temperature,pH,auxiliaries and mordant were calculated.Results The results showed that the optimum process for dyeing bio-based PA56 fabrics with madder pigment was as follows:dyeing pH value is 4.2,dyeing temperature is 80℃,dyeing time is 40 min and the amount of Peregal O is 1 g/L.After mordant dyeing,the K/S values of the dyed fabrics were significantly increased,and the color characteristics of dyed fabric changes obviously.Compared with the direct dyed fabric,the color fastness of the mordant dyed fabric has been improved.The kinetics of adsorption for different dye temperatures were evaluated by the pseudo first-order and second-order models.A large equilibrium adsorption density difference between the experiment and calculation was observed for the pseudo first-order model,indicating a poor pseudo first-order fit to the experimental data.The experimental data fitted well to the pseudo second-order kinetic model with high correlation coefficient above 0.999.In addition,the C∞ agreed well with both experiment and calculation,suggesting that the second-order kinetic model well describes the adsorption of madder pigment onto PA56 fiber.The half-dyeing time decreased,and the diffusion coefficient increased with increasing temperature.The influences of dyeing pH,auxiliaries and mordant on the dyeing kinetic parameters were further analyzed.With the increase of pH value,the equilibrium adsorption amount decreased,the half-dyeing time was shortened,and the diffusion coefficient was increased.The addition of sodium sulfate and Peregal O reduced the equilibrium dyeing amount and the half-dyeing time of maddering dye.The rate constant(k2)and the diffusion coefficient were increased with the addition of sodium sulfate and Peregal O.After mordant dyeing,the equilibrium adsorption amount was decreased,the half-dyeing time increased and the diffusion coefficient decreased,but K/S values of the dyed fabrics were increased.Conclusion The optimal conditions and dyed fabric with darker color of bio-based PA56 dyed with madder pigment were obtained.The type and mode of mordant can enrich the color tone and improve the color fastness.Fitting calculations reveal that the dyeing process of madder pigment dyeing on bio-based PA56 fabrics conforms to the pseudo second order kinetic model.Madder has a fast adsorption rate on PA56 fabric.The adsorption capacity was dependent with pH value.The addition of sodium sulfate and Peregal O,as well as the pretreatment with mordant,the dyeing processes also conform to the quasi-second order kinetic model.
NETL
NSTL
万方数据
