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     

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.     

An international inter-laboratory trial of the proposed ISO 105-C08 test procedure: a single wash test protocol using a detergent incorporating a lowtemperature bleach activator

A new single wash test procedure, ISO 105-C08, has been developed using a reference detergent, perborate and TAED (a low-temperature bleach activator) in order to better reflect domestic practice. Following an international trial, the procedure has been shown to be fully acceptable for the purpose of inter-laboratory comparisons.     

棉织物漂染废水的污染预测

为明确棉织物漂染废水中污染物的组分,采用m(BOD5)/m(CODCr)法测试了常用染料和助剂的可生化性,按实际漂染工艺和配方对棉织物进行前处理、染色和柔软处理,收集各阶段试验废水并进行分析。研究结果表明,棉织物漂染废水的CODCr主要由各种难降解的助剂和棉织物上的有机物所组成,其中各种难降解助剂的CODCr占废水总CODCr的63.3%,残余染料造成的色度高达800倍,柔软剂的CODCr在漂染废水总CODCr中所占的比例最大,约为57.5%。     

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.     

Process of dyeability modification and bleaching of cotton in a single bath

Graft polymerisation of the cationic monomer, methacryloylaminopropyltrimethylammonium chloride (MAPTAC), onto scoured cellulose was carried out in the bleaching process, aiming at modifying the fibre using a single bath. The extent of MAPTAC fixation on cellulose was measured. The bleaching performance of hydrogen peroxide in the presence of the modifying agent was found to be slightly reduced. The modified bleached cotton fabric was then dyed with a commercial reactive dye in the absence of salt. The dye uptake and colour strength of the modified fabric was markedly increased with an increase in the concentration of MAPTAC. This was attributed to the presence of the cationic groups of the MAPTAC which played a crucial role in attracting the anionic dyes from the dyebath. The results suggest that the dyeing properties of the modified fabric are closely dependent on the efficiency of MAPTAC fixation on cellulose during concurrent modifying and bleaching of cotton.     

二氧化氯在精制棉漂白上的应用

国产精制棉采用二氧化氯漂白工艺,粘度可超过１０００ｍＰａ·ｓ,白度可达特级水平,创出国内一流的优质精制棉。二氧化氯应用于精制棉的漂白,国内尚属首次。     

Salt-free dyeing of cotton cellulose with a model cationic reactive dye

A model cationic reactive dye based on an anthraquinone chromophore was prepared. The synthesis of this dye was achieved by the modification of the a free amino group of an anthraquinone-based dye, reacting first with cyanuric chloride and then with N -(2-aminoethyl)pyridinium chloride. TLC analysis was employed to follow the chemical reactions. The application of the prepared dye to cotton fabric was carried out using the exhaustion method without the addition of electrolytes. The results showed that, despite no electrolytes being present in the dye bath, a high percentage of dye exhaustion could be obtained. The high percentage of dye exhaustion was attributed to the attractive force between positive charges on the dye molecule and the negatively charged fibre surface. A high degree of dye fixation with excellent wash fastness was also achievable. Advantageously, it was found that this cationic reactive dye showed promising fastness to light when compared with that of analogous conventional basic dye on cotton. It is believed that the pyridinium cationic moiety, which attached separately to the chromophore via aliphatic spacer groups, was later eliminated during the washing-off process, hence causing an insignificant effect on the photofading of the dyed fabric.     

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.     

Novel bleach activator compounds derived from the reaction of isocyanic acid with selected nucleophiles

Laundry detergents commonly contain bleach activators that react with the perhydroxy anion produced from perborate or percarbonate anions to form activated peroxy compounds; these enhance bleaching and stain removal capacity especially at lower temperatures, hydrogen peroxide being an inefficient bleach below 60°C. The most commonly used activators are N, N, N′, N′-tetraacetylethylenediamine (TAED) and sodium nonanoyloxybenzenesulphonate (SNOBS) the former being used across Europe whereas the latter is used widely in the United States and Japan. This research studies the preparation of novel activator compounds which are carbamylated derivatives of selected nucleophiles using either solid or aqueous reactions of nucleophilic carboxylate anions with the highly reactive isocyanic acid entity derived from the acidification of sodium cyanate. The novel activator compounds were then assessed as bleach activators by testing against tea and bilberry-stained cotton reference fabrics at 40°C in the presence of hydrogen peroxide at pH values ranging from 4 to 10; bleaching efficiency was assessed visually and colorimetrically. Results showed that all of the synthesised compounds were more effective bleach activators across the pH range tested than the standard TAED system.     

Surface modification to improve dyeing of cotton fabric with a cationic dye

Sodium styrene sulphonate, a polymerisable anionic surfactant, was polymerised on cotton to impart a negative charge on the fibre surface. This enabled the fibre to be dyed with a cationic dye with no addition of salt. The treated cotton was dyed with a cationic dye to determine the amount and uniformity of the coating. The resulting dyed treated fabric shows good washing fastness at 30 °C and excellent dry rub fastness.     

季铵型阳离子聚丙烯酰胺的无盐染色行为

以季铵型阳离子聚丙烯酰胺作为一种新的阳离子助剂对棉纤维进行处理,应用于活性染料无盐染色,对染色过程中染料与处理后棉纤维之间的吸附类型、吸附热力学及吸附动力学进行了研究。结果表明,无盐染色过程符合Langmuir吸附模型;吸附过程是放热自发进行的,低温有利于染料的吸附;吸附动力学符合二级动力学模型,属于化学吸附过程。与传统有盐染色结果相比,染色后的阳离子化棉纤维色深增加,染料利用率提高。     

Enhanced cationic photocuring of epoxides with styrene oxide as a reactive diluent

Styrene oxide [StO] has been investigated as a reactive diluent for cationic photocurable formulations to provide key requirements such as low viscosity and negligible odor, in addition to high photoreactivity. The formulations were composed of commercial cyclic ethers including epoxides and oxetanes in StO using diaryliodonium salt as a photoinitiator, and they gave enhanced photocuring by analyzing with differential photocalorimetry. In particular, the cationic formulations composed of StO, bisphenol A diglycidyl ether, (3-glycidoxypropyl)trimethoxysilane and others rendered improved mechanical and thermal properties when their photocured coatings were examined. The gel content and pencil hardness values of photocured films were determined to evaluate the formulations. For the mechanistic explanation of the enhanced photoreactivity, the polymer-bound benzyl cations formed by a chain process in the polymer chains comprising StO moieties were postulated to serve as additional sites for the initiation of cationic photopolymerization of StO and cyclic ether monomers.     

Enhanced water flux through graphitic carbon nitride nanosheets membrane by incorporating polyacrylic acid

Membranes assembled from two‐dimensional (2‐D) layered materials have shown potential use in water purification. Recently, a 2‐D graphitic carbon nitride (g‐C₃N₄) nanosheets membrane exhibits considerable separation performance in water purification. In this study, to further improve this water separation performance, polyacrylic acid (PAA) was introduced to tune the nanochannels formed between the g‐C₃N₄ nanosheets. The fabricated g‐C₃N₄‐PAA hybrid membranes possessed higher water flux without sacrificing much rejection rate compared with that of the g‐C₃N₄ membrane; however, noticeable fouling was observed upon addition of the PAA into the membrane composite structure. In addition, the effect of PAA on the morphology, surface hydrophilicity, separation performance, and antifouling properties of the g‐C₃N₄ membrane were examined in detail. Overall, incorporating PAA into the g‐C₃N₄ nanosheets membrane was an effective and convenient method to improve the water separation performance, which could promote the application of the 2‐D g‐C₃N₄ nanosheets membrane in practical ultrafiltration processes. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2181–2188, 2018     

Enhanced CO2 separation performance of mixed matrix membrane by incorporating amine-functionalized silica filler

Mixed matrix membranes (MMMs) owing to the tunable characteristics and functionalization ability can effectively substitute the highly intensive conventional membranes for industrial-scale CO₂ separation. Further, to strengthen the interfacial polymer-filler interaction, an interfacial design strategy incorporating active functional groups in the filler surface can be demonstrated. In this study, as-synthesized silica nanoparticles (SNPs) was surface functionalized by (3-aminopropyl) trimethoxysilane silica modifier (AFSNP). The CO₂ separation of poly (vinyl alcohol)/polyethylene glycol based MMM infused with surface-functionalized SNP (AFSNP) was conducted. The comparative study highlighted in-depth analysis of intrinsic physicochemical properties of as-synthesized membranes and nanoparticles. Detailed characterization such as advanced microscopic analysis, X-ray photoelectron spectroscopy (XPS) analysis and ninhydrin assay validated the successful grafting of amino groups onto the silica surface. The morphological inspection corroborated the consistent dispersion ability of the nanoparticles in the membrane matrix. The effect of the operating conditions on the membrane selectivity and CO₂ permeance were statistically analyzed by ANOVA. The CO₂ permeation result (CO₂ permeance and CO₂/N₂ selectivity) exhibited many fold increment with surface functionalization of SNPs compared to undoped silica MMM. The defect-free, performance-oriented CO₂-selective membrane thus opened up the possibility of this combination as a prospective contender for large-scale carbon capture studies.     

Enhanced ethanol pervaporative selectivity of polydimethylsiloxane membranes by incorporating with graphene oxide@silica core-shell structure

A graphene oxide@silica core-shell structure (GO@silica) was prepared and embedded into the polydimethylsiloxane (PDMS) to fabricate mixed matrix membranes (MMMs). Meanwhile, (3,3,3-trifluoropropyl)triethoxysilane (TFTS) was employed to improve the compatibility between PDMS and GO@silica and create a hydrophobic membrane surface for improving the ethanol pervaporative performance. The scanning electron microscope (SEM) result showed that the resultant PDMS/GO@silica MMMs were smooth and defect-free. Meanwhile, the increase in hydrophobicity, swelling degree, and PV performance was achieved because of the incorporation of the modified GO@silica. The maximal separation factor of 11.43 coupled with a high permeation flux of 223 g·m⁻²·h⁻¹ was observed when separating a 10 wt. % ethanol/water mixture at 30°C. Moreover, the MMMs displayed a stable PV performance during a 168-h continuous operation.     

Bentonites modified with anionic and cationic surfactants for bleaching of crude palm oil

Bentonite Pacitan was modified with cetyl trimethylammonium bromide (CTAB) and LAS for bleaching crude palm oil. The organo-bentonites were prepared by normal heating and microwave irradiation. The advantage of using microwave irradiation is time efficiency. The bentonites were characterized by FTIR and XRD analysis. LAS modified bentonite was more effective as bleaching agent than CTA-bentonite.     

Enhanced oil recovery from high‐salinity reservoirs by cationic gemini surfactants

In order to enhance oil recovery from high‐salinity reservoirs, a series of cationic gemini surfactants with different hydrophobic tails were synthesized. The surfactants were characterized by elemental analysis, infrared spectroscopy, mass spectrometry, and ¹H‐NMR. According to the requirements of surfactants used in enhanced oil recovery technology, physicochemical properties including surface tension, critical micelle concentration (CMC), contact angle, oil/water interfacial tension, and compatibility with formation water were fully studied. All cationic gemini surfactants have significant impact on the wettability of the oil‐wet surface, and the contact angle decreased remarkably from 98° to 33° after adding the gemini surfactant BA‐14. Under the condition of solution salinity of 65,430 mg/L, the cationic gemini surfactant BA‐14 reduces the interfacial tension to 10^?3 mN/m. Other related tests, including salt tolerance, adsorption, and flooding experiments, have been done. The concentration of 0.1% BA‐14 remains transparent with 120 g/L salinity at 50 °C. The adsorption capacity of BA‐14 is 6.3–11.5 mg/g. The gemini surfactant BA‐14 can improve the oil displacement efficiency by 11.09%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46086.     

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.