Cationic Bleach Activator Research Articles

Facile synthesis of a novel, highly effective, more sustainable and cost-effective cationic bleach activator for cotton: N-[4-(N,N,N)-triethylammoniumchloride-butyryl] caprolactam

Compared to conventional peroxide bleaching, using a bleach activator in a peroxide bleaching bath is an effective and kinetically more potent oxidation generating highly reactive peracid in situ, providing low-temperature bleaching with shorter dwelling time. In the presence of an activator, bleaching can be achieved at lower temperatures and reduced time relative to the conventional peroxide bleaching, resulting in decrease in energy consumption and reduced fabric damage. Cationic bleach activators were investigated as the next generation bleach activators that exhibit inherent substantivity towards cellulosic fibers. In this study, facile synthesis of a more sustainable and cost-effective bleach activator, based on an aliphatic acyl chloride (4-chlorobutyryl chloride), was reported: Compared to aromatic-based bleach activator, it showed comparable bleaching results at lower temperature. Fourier transform infrared and high resolution mass spectrometry confirmed the molecular structure of the named activator: N-[4-(N,N,N)-triethylammoniumchloride-butyryl] caprolactam, TBUCC. Bleaching performance of TBUCC was evaluated in terms of whiteness index, water absorbency and fiber damage and compared with conventional peroxide system. Results revealed that our developed TBUCC-activated bleaching system provided comparable whiteness index, water absorbency with a higher degree of polymerization at significantly lower temperature (70 °C) as compared to conventional peroxide bleaching.

Synthesis, Characterization, and Toxicological Properties of New Cationic Bleach Activators

AbstractThree new bleach activators for cotton containing pyridinium (PBBC), nicotinamido (NABBC), and 3‐methylpyridinium (3‐PBBC) cationic groups were synthesized and characterized by 1H NMR and HPLC–mass spectrometry. They were then applied to cotton fabric in a bleaching process and evaluated for their performance against the prototype N‐[4‐(triethylammoniomethyl)benzoyl]butyrolactam chloride (TBBC) at a relatively low bleaching temperature (55 °C) and pH 8.5. Measurement of Commission internationale de l’éclairage (International Commission on Illumination) (CIE) whiteness index (WI) values showed that PBBC (WI = 64), NABBC (WI = 58), and 3‐PBBC (WI = 71) impart a significant increase in CIE whiteness compared to a control sample (WI = 40). Among the three new activators, 3‐PBBC exhibited the best performance. Its WI was comparable to that of fabric bleached using the prototype bleach activator TBBC. The acute toxicity of TBBC and the new bleach activators was evaluated using the microcrustacean Daphnia similis. The chronic toxicity of TBBC and 3‐PBBC was evaluated using the green alga Raphidocelis subcapitata, and mutagenicity was evaluated in the Salmonella/microsome assay using the strain TA100. 3‐PBBC was 86 times less toxic to D. similis, 18 times less toxic to R. subcapitata, and 10 times less mutagenic to TA100 in comparison with TBBC.

Synthesis of N‐[4‐(dimethylalkylammoniomethyl) benzoyl]caprolactam chlorides as cationic bleach activators for low‐temperature bleaching of cotton fabric under near‐neutral pH conditions

Low‐temperature bleaching of cotton fabric can be achieved by incorporating a so‐called bleach activator into an aqueous solution of hydrogen peroxide. In this study, a series of N‐[4‐(dimethylalkylammoniomethyl)benzoyl]caprolactam chlorides were synthesised for use as cationic bleach activators with various alkyl chain lengths. All these synthesised cationic bleach activators were confirmed by 1H and 13C nuclear magnetic resonance spectroscopy and mass spectroscopy. Bleaching experiments revealed that these synthesised bleach activators were effective for bleaching of cotton fabric at 50 °C under near‐neutral pH conditions, but the alkyl chain lengths had a great influence on their bleaching performance. Increasing the alkyl chain length from 2 to 6 carbon atoms could slightly enhance bleaching performance, while increasing the alkyl chain length from 8 to 16 carbon atoms markedly reduced bleaching performance.

Low Temperature Bleaching of Cotton with a Novel Cationic Activator

A new cationic bleach activator (CBA) N-[4-pyridmoniomethyl)benzoyl]caprolactam bromide (PBCB) was synthesized and evaluated in a hot peroxide bleaching process. The effects of time, temperature and the concentrations of hydrogen peroxide and activator on the bleaching of cotton fabric were investigated using an orthogonal experimental method. The optimal bleaching process of PBCB-activated peroxide system was 5g/L H2O2, 0.5g/L CBA, 40°Cand 45min dwell time under neutral pH, with which a whiteness equivalent to that of the conventional-bleaching system was achieved, but the PBCB system resulted in almost no fiber damage based on fabric strength.

Review of Bleach Activators for Environmentally Efficient Bleaching of Textiles

Textile wet processing is the most polluting aspect of textile manufacturing and contributes to the global textile industry’s substantial carbon footprint. Textile preparation of cotton typically includes scouring and bleaching at high temperature and high pH. Substantial amounts of wastewater are produced that must be treated prior to being released to receiving fresh water. Recent research in our laboratories has focused on the development and application of compounds that enhance the bleaching process. We have developed novel cationic bleach activators that can be used to bleach cellulosic fabrics and flber blends at reduced temperature, pH, and time. Results show that after optimization equivalent or improved performance in whiteness, absorbency and strength are possible relative to conventional bleaching methods. One of the most promising bleach activators to date is N-[4-(Triethylammoniomethyl) Benzoyl]-Butyrolactam Chloride (TBBC). TBBC was designed in our group to a) exhibit strong oxidation potential when activated; b) have reasonable hydrolytic stability; and c) be inherently substantive towards cellulosic and other flbers. In this paper, we review the development of bleach activators for textile bleaching, and discuss the opportunities and potential hurdles involved in commercialization of bleach activators for textile wet processing.

Bleaching cellulosic fibers via pre-sorption of N-[4-(triethylammoniomethyl)-benzoyl]-butyrolactam chloride

The sorption of a novel cationic bleach activator, N-[4-(Triethylammoniomethyl)benzoyl]-butyrolactam Chloride (TBBC), was measured on regenerated bamboo fiber. At 25 °C near neutral pH, the sorption rate of TBBC onto the fiber was initially rapid and equilibrium was reached within 20 min. Adsorption equilibria experiments followed a Freundlich isotherm. At the sorption equilibrium, bleaching was initiated by addition of sodium perborate to liberate hydrogen peroxide, which reacted with TBBC to generate a peracid that is a more kinetically active oxidant than peroxide. A sorption–activation model was developed that supports the enhanced bleaching of cellulosic fibers using cationic bleach activators under neutral to alkaline conditions.

Activated peroxide bleaching of regenerated bamboo fiber using a butyrolactam-based cationic bleach activator

Regenerated bamboo fibers are potentially a valuable source of renewable fibers for use in a wide variety of applications. As with almost all natural fibers, inherent yellowness must be reduced or eliminated in order for the fibers to be used effectively in processes such as dyeing. Oxidative bleaching in the form of hot alkaline hydrogen peroxide is the most common method for bleaching cellulosic fibers. However, significant fiber damage results, especially in the case of regenerated bamboo. Recently, more benign oxidative bleaching methods have been developed using so-called bleach activators. Reported is an effective bleaching method using a novel bleach activator, N-[4-(triethylammoniomethyl)benzoyl]butyrolactam chloride (TBBC). The ratio of TBBC to hydrogen peroxide and pH were found to be critical to achieving effective bleaching at low temperature. Using equimolar amounts of TBBC and hydrogen peroxide at pH 7 and 50 °C, comparable whiteness and less fiber damage compared with conventional peroxide bleaching was obtained. However, at pH 11.5, TBBC had no effect on whiteness.

Hydrolytic stability of a series of lactam-based cationic bleach activators and their impact on cellulose peroxide bleaching

A series of five cationic bleach activators containing lactam-based leaving groups of varying ring size was synthesized and characterized. The hydrolytic stability of each activator was determined via HPLC-based analysis of hydrolysis products, titration of available oxygen, and whiteness assessment of cellulosic fibers using a peroxide-activator bleaching system following solution storage for various times under controlled conditions. Aqueous alkaline solutions of each activator hydrolysed at different rates with the slowest rates observed with the ω-octalactam ring system, the largest ring size investigated, and the most rapid hydrolysis was found with a six-membered lactam ring based activator. The whiteness of cotton bleached with stored bleach activator solutions inversely correlated with the hydrolysis rate for each activator. The hydrolysis rate followed pseudo first order kinetics.

Enhanced PAA bleaching of cotton by incorporating a cationic bleach activator

Peracetic acid is a well‐known alternative to hydrogen peroxide as a bleaching agent for cotton. In this study, a novel cationic bleach activator, N‐[4‐(triethylammoniomethyl)benzoyl]butyrolactam chloride, was used in combination with peracetic acid to investigate the enhancement of cotton bleaching efficiency. The effects of temperature, pH and concentrations of activator and peracetic acid on the bleaching performance were studied using a statistical design of experiment. Adding activator to a peracetic acid bleaching bath improved the resultant whiteness of the substrate and at optimal conditions produced less fibre damage than when peracetic acid was used alone. In addition, the bleaching performance of both peracetic acid and hydrogen peroxide in the presence of activator was compared. In the absence of activator, the peracetic acid performance was considerably superior to a conventional hydrogen peroxide bleach system in which no bleach activator is present. However, addition of activator to the hydrogen peroxide bath increased the whiteness to a level comparable to peracetic acid.

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.

Stability of a novel cationic bleach activator in aqueous solution

The hydrolytic stability of a novel cationic bleach activator, N-[4-(triethylammoniomethyl)benzoyl]capro-lactam chloride, in aqueous solution has been investigated. After treatment with a bleach system, the whiteness of cotton fabric was measured. Assessment of the available oxygen was used to assess the stability of the bleach activator in solution with respect to time, using a method which minimised the effect of hydrogen peroxide on total available oxygen. Whereas the N-[4-(triethylammoniomethyl)benz-oyl]caprolactam chloride in solid form was found to be stable, in aqueous solution it was relatively easily hydrolysed. The effect of pH on its stability in solution was assessed. A good correlation was found between change in available oxygen on storage and bleaching performance.

Evaluating Hydrogen Peroxide Bleaching with Cationic Bleach Activators in a Cold Pad-Batch Process

Bleach activators generate peracids in the presence of hydrogen peroxide and alkali that are more potent oxidizing agents than hydrogen peroxide under comparable bleaching conditions. The effects of key bleaching parameters (activator concentration, hydrogen peroxide, chelant, and pH) on the performance of cold pad-batch bleaching on cotton are investigated. Optimized recipes are determined for two cationic activators, N-[4-(triethylammoniomethyl) benzyl]ca prolactam chloride and 6-( N,N,N-trimethylammonio) hexanoyl caprolactam p-toluenesulfo nate, using a central composite experimental design. The laboratory optimized conditions are used for pilot plant scale bleaching of cotton knit fabric. CIE whiteness index values are calculated from measured reflectance data of the pilot scale bleaching and are in close agreement with those predicted by the experiment. A high level of whiteness ( CIE WI > 70) is achieved for both activators with 8-hour batching, and measurements of the degree of polymerization of the bleached and greige fabrics show little fiber damage in each case.

Performance of a new cationic bleach activator on a hydrogen peroxide bleaching system

The performance of a cationic bleach activator, N‐[4‐(triethylammoniomethyl)benzoyl]caprolactam chloride, was evaluated in a hot peroxide bleaching process. The effect of time, temperature and the concentrations of hydrogen peroxide and activator on the bleaching of cotton fabric was investigated using a central composite experimental design. Temperature was found to be the most significant parameter. By adding the cationic activator it was possible to achieve a level of whiteness comparable to a typical commercial bleaching system but under relatively mild conditions of time and temperature. As a consequence, chemical damage to the fabric could be reduced. The effect of the cationic bleach activator was compared to that of an anionic activator, nonanoyloxybenzene sulphonate. The cationic activator was superior to the anionic activator in bleaching the fabric under the optimised conditions used in the study. Received: 13 January 2004, Accepted: 10 March 2004