Jinmei Du

The TAED/H2O2/NaHCO3 system as an approach to low-temperature and near-neutral pH bleaching of cotton.

A low-temperature and near-neutral pH bleaching system was conceived for cotton by incorporating TAED, H2O2 and NaHCO3. The TAED/H2O2/NaHCO3 system was investigated and optimized for bleaching of cotton using a central composite design (CCD) combined with response surface methodology (RSM). CCD experimental data were fitted to create a response surface quadratic model (RSQM) describing the degree of whiteness of bleached cotton fabric. Analysis of variance for the RSQM revealed that temperature was the most significant variable, followed by [TAED] and time, while [NaHCO3] was insignificant. An effective system was conducted by adding 5.75 g L(-1) TAED together with H2O2 and NaHCO3 at a molar ratio of 1:2.4:2.8 and applied to bleaching of cotton at 70 °C for 40 min. Compared to a commercial bleaching method, the TAED/H2O2/NaHCO3 system provided cotton with comparable degree of whiteness, slightly inferior water absorbency and acceptable dyeability, but had competitive advantage in protecting cotton from severe chemical damage in bleaching.

Analysis of factors affecting the performance of activated peroxide systems on bleaching of cotton fabric

Abstract A screening experiment was designed to investigate the possible factors affecting the performance of activated peroxide systems (APSs) on bleaching of cotton fabric. The design of experiment comprised thirteen factors such as type of bleach activator (BA), concentration of bleach activator ([BA]), molar ratio of hydrogen peroxide to bleach activator ([H2O2]:[BA]), type of peroxide stabilizer (PS), concentration of peroxide stabilizer ([PS]), type of wetting agent (WA), concentration of wetting agent ([WA]), pH value of bleach bath (pH), bleaching temperature (T), bleaching time (t), liquor-to-goods ratio, cotton substrate (C), and water quality (W). The bleaching performance of APSs was accessed by measuring the degree of whiteness of bleached cotton fabric which was defined as the response factor for statistical analysis. The screening analysis revealed that C was the most significant factor affecting the performance of APSs on bleaching of cotton fabric, followed by T, BA, [BA], pH, PS, and [H2O2]:[BA]. Additionally, two-factor interactions were found as well between C and T, T and pH, C and BA, C and [BA], T and [BA], W and [PS], C and PS, and pH and [H2O2]:[BA]. These significant main effects and two-factor interactions were interpreted in details for a better understanding of the performance of APSs on bleaching of cotton fabric. The findings of this study are valuable for further establishment and optimization of APSs for low-temperature bleaching of cotton fabric.

Performance modelling of the TBCC-activated peroxide system for low-temperature bleaching of cotton using response surface methodology

Abstract In this study, an activated peroxide system was established for low-temperature bleaching of cotton by incorporating N-[4-(triethylammoniomethyl)benzoyl]caprolactam chloride (TBCC), hydrogen peroxide (H2O2) and sodium bicarbonate (NaHCO3) into an aqueous solution. The bleaching performance was modelled by response surface methodology based on a central composite rotatable design of experiment, in which concentration of TBCC ([TBCC]), concentration of NaHCO3 ([NaHCO3]), temperature (T) and time (t) were four independent variables, and the degree of whiteness (DoW) of bleached cotton was measured as the response variable. For each individual bleaching experiment, TBCC and H2O2 were used in a molar ratio of 1:1.1 and NaHCO3 in a molar amount greater than that of H2O2 for the purpose of driving reactions to completion. A reduced quadratic model (RQM) was constructed using regression analysis with backward elimination, which was used to conduct a practical low-temperature bleaching process for cotton. In comparison to the typical conventional peroxide system, the TBCC-activated peroxide system based on the RQM predication provided cotton with an equivalent DoW and slightly inferior water absorbency, resulted in no apparent damage to cotton fibers, but worked under much milder conditions. This study provides useful insights into scaling up the TBCC-activated peroxide system for low-temperature bleaching of cotton.

X-ray photoelectron spectroscopy analysis of cotton treated with the TBCC/H2O2/NaHCO3 system

N-[4-(triethylammoniomethyl)benzoyl]caprolactam chloride (TBCC) was used as a bleach activator for activation of hydrogen peroxide (H2O2) in aqueous solution with the addition of sodium carbonate (NaHCO3). The TBCC/H2O2/NaHCO3 system was applied for treatment of cotton greige fabric at 60℃ in comparison with the conventional H2O2/NaOH system for treatment of cotton greige fabric at 95℃. Experimental results showed that the TBCC/H2O2/NaHCO3 system was effective for improving the degree of whiteness, reducing the fiber damage, and improving the water absorbency of cotton fabric. For understanding the treatment performance of the TBCC/H2O2/NaHCO3 system, X-ray photoelectron spectroscopy (XPS) was applied to analyze the surface elemental composition of cotton greige fabric before and after treatment. C 1s XPS spectra and quantitative analysis revealed that the TBCC/H2O2/NaHCO3 system improved the water absorbency of cotton fabric by removing hydrophobic matters as well as by oxidizing coloring matters and cellulose. The hexane extractions and scanning electron microscopy images indicated that the TBCC/H2O2/NaHCO3 system most likely removed the hydrophobic matters from cotton fabric in a “layer-by-layer” mode, which limited the cellulose backbones exposed for XPS analysis but allowed water to penetrate into cotton fibers.

Emulsion polymerization of N-halamine polymer for antibacterial polypropylene

N-halamines are highly efficient antibacterial agents. They can inhibit or inactivate bacteria by transformation of the N-Cl bond to an N-H bond, and be regenerated by chlorination. In this study, regenerable biocidal poly(VAc-co-MAM) was synthesized by emulsion polymerization with vinyl acetate (VAc) and methacrylamide (MAM). Polymerization was optimally carried out at 100℃ for 7 hours using a 10:1 molar ratio of VAc to MAM in the presence of 1% initiator in mass to the total of VAc and MAM. The synthesized polymer emulsion was used for antibacterial treatment of polypropylene (PP) nonwoven fabric. The treated fabric was found to have an active chlorine value of 0.21%, which exhibited excellent antibacterial activity. The active group N-Cl in PP fabric treated with poly(VAc-co-MAM) was unstable under ultraviolet irradiation, but could be recovered through chlorination. Poly(VAc-co-MAM) can be used as an antibacterial agent for many other fibers, not limited to PP, since it has a hydrocarbon chain that provides a good compatibility with other synthesized fibers through the Coulomb force and hydrophobic bond.

A nonlinear isotherm model for sorption of anionic dyes on cellulose fibers: a case study.

The sorption data of an anionic dye on cellulose fiber are often correlated with a log-linear model to determine the internal accessible volume of the fiber to the anionic dye (V, L/kg) and as such the standard affinity of the anionic dye to the fiber (-Δμ°, J/mol), but without taking into account the influence of ionized carboxyl groups due to cellulose oxidation ([COO(-)]f, mol/kg). In this study, a nonlinear isotherm model was derived by incorporating [COO(-)]f, V and -Δμ° as three model parameters. A set of classical sorption data of C. I. Direct Blue 1 on bleached cotton was correlated with the nonlinear isotherm model. The nonlinear curve fitting analysis showed that the nonlinear isotherm model was in excellent agreement with the sorption data and robust to determine the values of [COO(-)]f, V and -Δμ° for describing the sorption behaviors of anionic dyes on cellulose fibers.