An evaluation of the effectiveness of applying a gelatin–copper complex in the low-temperature bleaching of cotton with hydrogen peroxide

A gelatin–copper complex was prepared and then added as catalyst to a hydrogen peroxide bleaching bath. Cotton fabric was bleached with the new system at low temperature (70 °C). The effects of the gelatin–copper complex on the whiteness, capillary effect, damage, and bleaching rate of the bleached fabric and on the decomposition ratio of hydrogen peroxide were evaluated. These effects were compared with the effectiveness of traditional high-temperature bleaching and low-temperature bleaching without the gelatin–copper complex. The results showed that the gelatin–copper complex enhances the bleaching effectiveness of hydrogen peroxide. The whiteness of cotton fabric bleached with the catalytic complex is comparable with the whiteness achieved with a conventional peroxide system. The catalytic bleaching technology not only realises low-temperature and low-alkali bleaching of cotton with hydrogen peroxide but also reduces fabric strength loss, which meets the requirements of industry for continued development of the wet processing of textiles.     

Single stage process for desizing,scouring, and bleaching of cotton fabric

The efficiency of a treating bath formulation consisting of H₂O₂, sodium hydroxide, chelating agents, wetting agent, metal ions, and MgSO₄ · 7H₂O in effecting combined desizing, scouring, and bleaching of cotton fabric using a winch beck system was investigated under different conditions. Presence of MgSO₄ · 7H₂O at a concentration of up to 3 g/l was essential for stabilization of the strongly alkaline H₂O₂ solutions (containing 10 g/l NaOH) at 95°C for 90 min to achieve complete starch removal and to bring about fabric with satisfactory whiteness and absorbency without seriously degrading the fibre substance. Chelating agents, namely EDTA and gluconic acid (2 g/l, each) assisted in stabilization of H₂O₂ even in presence of Fe³⁺, Cu²⁺ or both ions and resulted in improved whiteness and lower fibre degradation but had no effect on residual starch or on wettability of the fabric. The wetting agent used had no significant effect on stabilization of H₂O₂ and fibre degradation, but it helped starch removal and improved the wettability of the fabric. The decomposition of H₂O₂ increased by increasing its own concentration from 2 to 12 ml/l as well as the concentration of sodium hydroxide from 5 to 17.5 g/l. The same hold true for temperature (60 to 98°C) and duration (30 to 150 minutes). Combined desizing, scouring, and bleaching of loomstate cotton fabric could successfully be effected by using a treating bath consisting of sodium hydroxide (10 g/l), H₂O₂ (4 ml/l), MgSO₄ · 7H₂O (3 g/l), EDTA (2 g/l), gluconic acid (2 g/l), anionic/nonionic wetting agent (1.5 g/l) at 95°C for 90 min, and a material : liquor ratio of 1 : 25.     

One‐step process for desizing and bleaching of cotton fabrics using the combination of amylase and glucose oxidase enzymes

Bacterial α amylases, widely used in the desizing of the gray cotton fabrics, convert the starch present in the warp yarns into glucose, a reducing sugar. An attempt has been made to convert the glucose released by amylases in the desizing process into hydrogen peroxide using glucose oxidase enzymes and use the hydrogen peroxide for bleaching of cotton fabrics, in a single step. Conversion of glucose, into hydrogen peroxide, is influenced by aeration of the reaction bath and concentration of the glucose oxidase. Significant improvement in the whiteness and absorbency, reduction in the extractable impurities and clear surface morphology were also observed in the samples obtained from the one‐step process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

表面活性剂的混合乳化性质在退浆中的应用

将表面活性剂的混合乳化性质应用到棉线退浆中,讨论了表面活性剂复配比例、温度、pH值及处理时间等因素对退浆的影响。结果表明,表面活性剂退浆法最佳工艺条件为:十二烷基硫酸钠(SDS)30 g/L,AEO-9 5 g/L,十六烷基三甲基溴化铵(CTAB)30 g/L,OP乳化剂10 g/L,pH6.5~7.5,温度70~80℃,处理时间60 min,在此条件下,棉线失重率为14.2%,白度为80.6。     

Bioscouring of cellulosic textiles

A study on bioscouring of cotton yarn with the pectinase enzyme was carried out and the results compared with the usual alkali scoured material. The results indicate that the bioscoured yarn has lower percentage of non‐cellulosic constituents (impurities), higher tenacity, higher absorbency and the same whiteness after hydrogen peroxide bleaching as compared with the Solomatic bleached yarn. A similar study on cotton fabric indicates that a combined desizing and bioscouring is not feasible at least at ambient temperature. More work, however, is required to compare bioscouring followed by bleaching with the Solomatic or two step scouring and bleaching methods. One interesting finding is that the efficiency of washing of the desized fabric improves on adding ethylene diamine tetraacetic acid sequestrating agent in the wash liquor. Additional advantages of bioscouring are lower energy cost and more easily biodegradable effluent in comparison to alkali scouring.     

Low‐temperature bleaching of cotton fabric with a binuclear manganese complex of 1,4,7‐trimethyl‐1,4,7‐triazacyclononane as catalyst for hydrogen peroxide

Bleaching of cellulose fabric with hydrogen peroxide is traditionally conducted under alkaline conditions at high temperature, which leads to greater energy consumption and fibre damage. In this study, a binuclear manganese complex of the ligand 1,4,7‐trimethyl‐1,4,7‐triazacyclononane as the catalyst for hydrogen peroxide bleaching was synthesised via a simplified method. Low‐temperature bleaching of cotton fabric with the manganese complex and the effect of key bleaching variables on the bleaching performance were investigated. Hydrogen peroxide could be catalysed to bleach cotton knitted fabric at a temperature as low as 60 °C by incorporating the complex in the bleaching solution. The whiteness index of the fabric bleached at low temperature was lower than that of fabric bleached at high temperature, but the bursting strength retention is much better for the fabric bleached at low temperature. The low temperature is energy‐saving and has environment‐friendly advantages over the traditional high‐temperature method.     

Application of urea/H2O2 activation‐oxidation system in degradation of PVA and desizing of polyester/cotton fabric

The viscosity and the UV–vis spectrum of PVA degradation aqueous solutions, the FTIR, and DSC spectrums of degradation products were measured to investigate and compare the effect of Fenton's reagent and urea/H₂O₂ activate oxidation systems on the degradation of PVA. The results showed that the viscosity of PVA aqueous solution decreased and the degradation rate of PVA increased with the concentration of hydrogen peroxide in both activate oxidation systems. The FTIR and DSC spectrum of degradation products showed that the degradation products contained aldehyde, ketone groups. The aldehyde compounds and carbon dioxide produced in the degradation systems were validated by Fehling reagents and clarifying limewater. When the urea/H₂O₂ system was applied in the one‐bath and one‐step desizing and scouring process of polyester/cotton 65/35 fabric, the results of 94.7% degradation rate of PVA, the 99.0% desizing rate of PVA, the whiteness, and wicking height of the fabric were obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Development of a one-stage process for pretreatment and cationisation of cotton fabric

A one-stage process for cationisation and pretreatment of cotton fabric was developed. Cationisation of cotton cellulose was carried out with 3-chloro-2-hydroxypropyltrimethylammonium chloride, whereas pretreatment comprised enzymatic and oxidative desizing, scouring, bleaching with hydrogen peroxide, combined desizing and scouring as well as combined desizing, scouring and bleaching. Each of these pretreatment operations or their combination with and without cationisation was carried out using three techniques, namely, cold pad–batch, pad–steam and exhaustion. It was found that the cationisation chemicals were compatible with the scouring ingredients and, to a lesser extent, with the formulation of enzymatic desizing. On the other hand, cationisation chemicals were not compatible with oxidative desizing or peroxide bleaching ingredients. Efficiency of the one-step process for scouring and cationisation was maximised through detailed investigation of the process parameters. The treated fabric can be dyed without electrolyte and the fabrics show a high levelness of colour shade, residual wax content and nitrogen content.     

Cold pad–batch bleaching of cotton fabrics with a TAED/H2O2 activating system

The cold pad–batch bleaching of cotton fabrics using a tetra acetyl ethylene diamine/hydrogen peroxide (TAED/H₂O₂) activating system is investigated in this study. The effects of key bleaching parameters (hydrogen peroxide dosage, sodium hydroxide dosage, TAED/H₂O₂ mol ratio and batch time) on the bleaching efficiency were investigated by single‐factor analysis and orthogonal experiment analysis. The performance of the activator TAED in the cold pad–batch process was examined and the activating mechanism is discussed. The optimised bleaching recipe and processing conditions are reported, and the optimal activated bleaching process is also compared with a conventional cold pad–batch bleaching process. The results show that the optimised TAED/H₂O₂ activated bleaching system could achieve high quality cotton bleaching with comparable fabric whiteness to the conventional system at much shorter batch times, and with significantly reduced fabric strength loss and decreased alkali consumption, which would be beneficial to sustained development of the textile wet‐processing industry.     

Feasibility of a one–step process for desizing,scouring, bleaching and mercerisating cotton fabrics

In this study the desizing, scouring, bleaching and slack mercerising of cotton fabric by a one–step process at different sodium hydroxide concentrations, impregnation temperatures and curing times were examined. The results indicate that when the fabrics are mercerised at lower temperature, the strength retention and colour strength are enhanced. When the sodium hydroxide concentration is increased, these properties also increase. When cotton fabrics are mercerised for 3 min at 40C and cured for 30 s at 120C, their physical properties are similar to those obtained using a conventional two–step approach.     

Use of standing bath technique in peroxide bleaching of cotton

The use of a standing bath technique in hydrogen peroxide bleaching of cotton fabric was investigated. Two non-silicate stabilisers, a laboratory-formulated inorganic stabiliser and a commercial organic stabiliser, were used. The bleaching recipe was optimised for maximum whiteness and then used for the standing bath technique by replenishing the bath with the equivalent peroxide concentration and maintaining the pH. The level of replenishment of the stabiliser was varied up to 70% of the initial amount of stabiliser. The results, as assessed by CIE whiteness index, indicate that it is only possible to achieve similar whiteness levels to bleaching without a standing bath by replenishing the stabiliser with a large proportion of the original amount.     

Flame‐retardant finishing of cotton fabrics using polyamino carboxylic acids and sodium hypophosphite

The purpose of this research was to use polyamino carboxylic acids (PACAs) and their combination with sodium hypophosphite (NaH₂PO₂) as a flame‐retardant finishing system for cotton fabrics. Flammability of cotton fabric was evaluated by 45° flammability test, differential scanning calorimetry and measuring the char yield. The combination of polyamino carboxylic acids and sodium hypophosphite as a phosphorus‐containing catalyst reduces the flammability of cotton. The pyrolysis properties and the results of char yield of the finished cotton show that with increasing amount of catalyst, the flame retardancy increases. Fastness against multiple laundering, whiteness and tensile strength of the cotton finished with PACAs/NaH₂PO₂ to multiple standard laundering have been studied, too. The flame retardancy effect has an acceptable washing fastness. Whiteness and tensile strength of the finished cotton do not change significantly. Copyright © 2012 John Wiley & Sons, Ltd.     

The Effects of Ozone Treatment on Soybean Fibers

A set of knitted fabrics comprising soybean fibers was ozonated at room temperature for periods ranging from 2.5 to 300 minutes to identify any accompanying effects on either physical properties (specifically whiteness and burst-strength), fiber surface integrity or microstructure. A hydrogen peroxide treatment was applied to some of the fabric in order to provide a comparison. Ozonation was found to produce a promising increase in whiteness which, after the maximum exposure time, was significantly higher than was achieved using hydrogen peroxide.     

棉织物前处理洗涤废水的臭氧化处理及回用

采用自制的臭氧处理装置对棉针织物退、煮、漂-浴处理中产生的棉织物前处理洗涤废水进行了连续在线处理,并回用到洗涤工序中,以代替原来的工业用水。从织物的白度和毛效方面研究了洗涤废水的回用效果,臭氧化处理后的废水经5次回用,白度的下降幅度在5个白度值以内。随着回用次数的增加,织物吸水性有所提高。各试样布在后续染色加工中产生的色差在0.25以内。试验结果表明,废水回用所产生的影响不大。     

Bleaching of cotton fabric with peracetic acid in the presence of different activators

Peracetic acid is an efficient oxidant and a good alternative to conventional chemicals for bleaching cotton. In order to establish optimal conditions for its use, giving a high degree of whiteness and good water absorption without damage to the fabric, the chemistry of its consumption and the efficiency of the bleaching process have been examined. The effect of temperature and initial pH was assessed, and in particular the influence of the alkali used to control the pH. The highest and most rapid consumption of peracetic acid was seen with magnesium carbonate, the slowest with sodium hydroxide. The bleaching effect was greatest with sodium carbonate and least with sodium hydroxide, although the differences were not large. In all cases damage to the fabric was minimal. The best conditions for bleaching with peracetic acid were found to be 60 °C and an initial pH 7, in the presence of either sodium carbonate or magnesium carbonate.     

Bleaching of cotton with activated peroxide systems

The bleaching performance of a novel cationic bleach activator, N -[4-(triethylammoniomethyl)benzoyl]-caprolactam chloride, was compared to that of nonanoyloxybenzene sulphonate, a commercially available anionic bleach activator. The whiteness of bleached cotton fabric was used as a measure of the performance. Comparison of bleach performance and the effect of key variables were evaluated using a central composite experimental design. The performances of both activators increased with temperature and sodium hydroxide concentration. Also, the performance of the cationic bleach activator increased with activator concentration, while an increase in the concentration of nonanoyloxybenzene sulphonate gave an adverse effect on the performance. It was found that the cationic bleach activator was superior to the anionic activator in the hot bleaching of cotton under the conditions studied.     

Laccases to Improve the Whiteness in a Conventional Bleaching of Cotton

This study reports for the first time on the enhancement of the bleaching effect achieved on cotton using laccase enzyme. Laccases applied in short‐time batchwise or pad‐dry processes prior to conventional peroxide bleaching, improved the end fabric whiteness. The whiteness level reached in the combined enzymatic/peroxide process was comparable to the whiteness in two consecutive peroxide bleaches.

Effect of 10 min laccase pre‐treatment at 60 °C, pH 5 on fabrics whiteness before and after a conventional hydrogen peroxide bleaching.     

Optimization of the hot alkali treatment of polyester/cotton fabric with sodium hydrosulfite

The treatment of cotton or polyester fabric in alkali media is a common modification process for producing a fabric with desirable qualities. Alkali treatment of polyester/cotton fabric could produce a fabric with better performance. In this research, polyester/cotton fabric was treated with NaOH at different temperatures and times. The results show that alkali treatment at the optimum temperature and time with NaOH could hydrolyze the polyester fiber surface and remove some of the impurities from the cotton fiber at the same time and may also improve some of the fabric properties, such as fabric regain, water drop absorbency, and fabric pilling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:5049–5055, 2006     

Dyeing properties of cotton fibres treated with liquid ammonia

Both scoured and sodium hydroxide mercerised cotton fibres have been treated with liquid ammonia atndash33.4°C using commercial operating equipment and then the ammonia removed at 130°C in a hot drum. The moisture regain and water absorbency of the fibres treated with liquid ammonia were increased compared with values on untreated fibres, whereas both these parameters on mercerised cotton fibres were decreased by subsequent liquid ammonia treatment. The fibres were dyed with CI Direct Red 2 and CI Direct Blue 1. Liquid ammonia treatment of the scoured cotton fibres increased the rate of dyeing, equilibrium dye adsorption, standard affinity, heat of dyeing and change of entropy, while the dyeing properties of mercerised cotton were adversely affected by subsequent liquid ammonia treatment.     

Bleaching with sodium hypochlorite: Interactions of temperature,time, pH and concentration with stain removal and fabric strength

In response to recent concern for energy conservation while launder-ing at lowered temperatures, this study investigated stain removal and fabric degradation effects of sodium hypochlorite bleach on stained cotton fabrics. Blue and green reflectance readings were used to calculate both whiteness values and percentage of stain removal values, while tensile strength measurements were used to determine fabric degradation. An “acceptable bleach treatment” category was established, having a minimum of 75% whiteness and 90% of origi-nal breaking strength. Temperature, bleach concentration, time and pH were investigated, with each factor except pH being significant. Low bleach concentration was more satisfactory than high concen-tration, while cold and warm temperatures were more acceptable than very cold and hot temperatures. An overnight bleach soak treatment of up to 16 hr was not damaging if a cold temperature of 25 C was chosen. Selecting cold (room) temperatures for chlorine bleaching could provide energy savings for the consumer, textile mill or commercial laundry, while providing acceptable whiteness and fabric strength retention.