Dyeing Of Cotton Fabrics With Reactive Dyes In Waste Cooking Oil-water Dual Phase Systems

Cotton fibres,which account for 30%of global fibres production,are one of the most important fibres.Traditional reactive dyeing has become a major source of pollution for the world's textile industry due to effluent containing large quantities of hydrolyzed dyes.Generation of excessive hydrolyzed dyes and salts from traditional reactive dyeing is almost inevitable due to the dyeing mechanism.To meet increasingly stringent emission standards,the textile industry has been forced to head toward cleaner dyeing technology.New reactive dyeing technologies developed for several decades are difficult to meet eco-friendly,cost-effective,and safe simultaneously,and their applications have been limited due to the decrease of hydrolyzed dyes in traditional dyeing technology or the release of toxic organic solvents.In this research,a dual-phase dyeing system with controllable stability is designed based on waste cooking oil?WCO?and water,including WCO-H₂O suspension system for high brand reactive dyes and WCO-H₂O emulsion system for medium brand reactive dyes.The diffusion,adsorption and fixation process in WCO-H₂O dual-phase system were studied,and the difference in dyeing mechanism of reactive dyes between the WCO-H₂O dual-phase system and traditional aqueous system was compared.The affinity among water molecules,oil molecules and cellulose under different conditions were molecularly explored.The key technology of removal waste cooking oil from cotton fabrics was established.A low-cost post-treatment method to remove waste cooking oil from dyed cotton fabrics was realized.The key problem of residue waste cooking oil in the cotton fabrics was solved in WCO-H₂O dual-phase dyeing system.The degradation reaction of waste cooking oil in the WCO-H₂O dual-phase dyeing process was studied.The degradation products from waste cooking oil in the dyeing system were separated with low cost and high efficiency.The cyclic dyeing method of cotton fabrics with high dyeing quality in WCO-H₂O system was developed.Because cotton fabrics were commonly dyed with various reactive dyes,the reactive dyeing in WCO-H₂O system with three-primary dyes was analyzed.The compatibility of three-primary colors in the WCO-H₂O system was equivalent to that in traditional aqueous system.At the same time,the biodegradability of dyeing effluents generated from WCO-H₂O dual-phase dyeing system was verified.The industrial feasibility of the dual-phase dyeing system was investigated.?1?A WCO-H₂O dual-phase suspension dyeing system with high chemical potential was developed.The high brand reactive dyes were dispersed in waste cooking oil by ball-milling to form the suspension system?external phase?.The cotton fabrics fully swelled in sodium carbonate solution?internal phase?were added into the suspension dyeing system.Due to the high chemical potential of the reactive dyes dispersed in waste cooking oil,they will spontaneously move into the internal phase from the external phase and complete the adsorption,diffusion and fixation in cotton fabrics.Fixation isotherm and dyeing kinetics of dyeing process in WCO-H₂O suspension system and traditional aqueous system were studied.The fixation behavior of reactive dyes in the two systems were consistent with the Langmuir model.Fixation rates of reactive dyes for the WCO-H₂O dual-phase suspension system and traditional aqueous system were fitted to the second order model.However,fixation rate of reactive dyes in the WCO-H₂O dual-phase suspension dyeing system was slightly smaller than that of the traditional aqueous system.The difference in fixation rate constant from the two systems could be decreased with the increase of fixation temperature.The removal efficiency of waste cooking oil from cotton fabrics was studied by high performance liquid chromatography.It was found that the higher liquor pick-up in cotton fabrics,the easier the waste cooking oil was removed from the cotton fabrics.After a combination of post-treatment,such as vacuum,squeeze and dip-and-squeeze,more than 99%of waste cooking oil could be recovered from the dyeing system.Waste cooking oil on cotton fabrics was below the detection limit of HPLC after the conventional washing process.The degradation of waste cooking oil in the dyeing process lead to continuous decline of dyeing quality when the waste cooking oil collected from dyeing system was reused for additional dyeing cycles.However,after alkali refining of waste cooking oil,the dyeing quality of cotton fabrics returned to the initial level.After degraded by activated sludge,the COD value of dyeing effluents containing waste cooking oil and degradation products generated from the WCO-H₂O system was lower than the allowable concentration.A pilot scale of cotton fabrics with the WCO-H₂O dual-phase suspension system in jet dyeing machine was performed,and the dyeing quality of dyed cotton fabrics was close to that from the traditional aqueous dyeing.Material and wastewater treatment costs of the WCO-H₂O dual-phase suspension system are significantly lower than that of the conventional aqueous system.The pilot-scale dyeing and lower costs showed that the WCO-H₂O suspension system had a good industrial feasibility.?2?A WCO-H₂O dual-phase emulsion dyeing system with high controllable stability was developed.The vinyl sulfone dyes were dissolved in water and the emulsion dyeing system was formed by blending the dye solution and waste cooking oil at a high speed.After adding the cotton fabrics fully swelled in sodium carbonate solution,dried and conditioned into the emulsion dyeing system,the dye droplets dispersed in waste cooking oil could move from oil to cotton fabrics and be fixed onto cotton fabrics.Fixation isotherm and dyeing kinetics of dyeing process in WCO-H₂O emulsion system and conventional aqueous system were studied.The fixation behavior of reactive dyes in the two systems were consistent with the Langmuir model.Fixation rates of reactive dyes for the WCO-H₂O emulsion system and conventional aqueous system were fitted to the second order model.However,fixation rate of reactive dyes in the WCO-H₂O emulsion dual-phase system was smaller than that of the traditional aqueous system.The slower fixation rate helped ensure sufficient time for reactive dyes to diffuse and migrate in fabrics until evenly distributed.It was found that the higher total water content in emulsion system,the easier the waste cooking oil was removed from dyed cotton fabrics.After a combination of post-treatment,such as vacuum,squeeze,dip-and-squeeze and conventional washing process,waste cooking oil left in cotton fabrics was decreased below the detection limit of HPLC.The degradation of waste cooking oil in dyeing cycles lead to substantial decline of dyeing quality after the oil collected from dyeing cycles was reused for successive dyeing cycles.After the degradation products were removed by effective alkali refining,dyeing quality of cotton fabrics became the same as that in the first dyeing cycle.After degraded in activated sludge,the dyeing effluents containing oil and its degradation products generated from the WCO-H₂O emulsion system was lower than the allowable concentration.In addition,a pilot scale of the WCO-H₂O emulsion system in jet dyeing machine and material costs of comparison between of the traditional aqueous system and emulsion system showed that the WCO-H₂O emulsion system had a good industrial prospect.?3?The effects and mechanism of degradation products on dyeing quality were investigated to ensure dyeing quality controllably stable in circulated dyebath of waste cooking oil.The hydrolysis rate of waste cooking oil increased proportionally?R²=0.9843?when the number of dyeing cycles increased.About 1%of waste cooking oil was hydrolyzed to glycerol and sodium fatty acid after each dyeing cycle,which decreased the dyeing quality of the WCO-H₂O dyeing system.The two major hydrolysates had different effects on the degradation of dyeing quality.Glycerol had much weaker capability in swelling cotton.Glycerol diffused into the internal phase,and dissolved alkali from water,causing decrease of p H of the internal phase.Glycerol could also compete with water molecules and hydroxyl groups on cellulose to attract dye molecules in the internal phase.The dissolution of sodium fatty acid in the internal phase did not obviously increase the overall p H value.When the concentration of sodium fatty acid in the internal phase of WCO-H₂O dyeing system exceeded500 g/L,reactive dye molecules would associate with each other to form more aggregates and fixation rate decreased by about 10%.The tensile strength of cotton fabrics dyed in WCO-H₂O dyeing system decreased by 10%compared with that before dyeing,which was almost the same as that in traditional aqueous system.Reactive dyeing in WCO-H₂O system did not affect the crystallinity of cotton fibers,and the degrees of crystallinity of undyed cotton,cotton dyed in WCO-H₂O system were 78.5%and 77.3%,respectively.?4?The feasibility of color matching with reactive dyes from WCO-H₂O dyeing system was verified.The difference in fixation rate of three primary dyes from WCO-H₂O dyeing system and traditional aqueous system was less than 5%.With the increase of amount of three primary dyes,the fixation behavior of three primary dyes in WCO-H₂O system had a good linear relationship?R²>0.98?.When the total amount of three primary dyes on cotton fabrics were almost equal,the color difference between the cotton fabrics dyed from the WCO-H₂O system and traditional aqueous system was within 0.6.After the oil collected from dyeing process was refined and reused for dyeing cycles,the color matching of three primary dyes became stable.The cotton fabrics dyed with three primary dyes from the WCO-H₂O system and traditional aqueous system showed comparable colorfastness to light,to crocking and to laundering,which proved the WCO-H₂O dyeing system have great potential to replace the traditional aqueous dyeing system.Dual-phase suspension and emulsion dyeing systems consisting of waste cooking oil and water with controllable stability were proposed for salt-free dyeing and low discharge.The pilot-scale jet dyeing with WCO-H₂O dual-phase system demonstrates industrial feasibility.Research of WCO-H₂O dual-phase system provided theoretical and technical support for reducing the negative impacts on environment from the traditional reactive dyeing.