Plasma-assisted regenerable chitosan antimicrobial finishing for cotton

In this study, nitrogen-plasma treatment was used to enhance the coating of chitosan onto cotton fabric and chlorine was introduced into nitrogen-containing groups on the chitosan coated fabric in order to make it antimicrobial by chlorination with sodium hypochlorite. The antimicrobial property and its rechargeability were investigated. FTIR, UV and scanning electron microscope were used to evaluate the surface properties, including the existence of chitosan on cotton fabric, the content of chitosan on cotton fabric and the surface topography of cotton fabric after modification. The results showed that nitrogen-plasma introduces nitrogen-containing groups into cotton fabric, the coating of chitosan on fabric was improved with nitrogen plasma treatment and chlorine was introduced into the chitosan coated fabric successfully which inhibits bacteria effectively and it is rechargeable. Thus, the antimicrobial property of cotton fabric coated with chitosan with the aid of nitrogen-plasma treatment after chlorination achieved good effects.     

Salt-free dyeing of ramie fabric with an amino-terminated hyperbranched polymer

A new amino-terminated hyperbranched polymer (at-HBP) was synthesized, and its salt-free dyeing property on ramie fabric was studied. The structure and molecular weight of at-HBP were established by Fourier transform infrared spectrometer, H nuclear magnetic resonance and gel permeation chromatography. The untreated ramie fabric and modified ramie fabrics were characterized by an X-ray diffraction (XRD) and field emission scanning electron micrograph (FE-SEM). XRD results showed a transformation of the crystalline structure from ramie cellulose I to cellulose II allomorph during mercerization and epichlorohydrin modification, and the crystalline structure of cellulose II was maintained with an obvious crystallinity index increase after at-HBP modification. FE-SEM results confirmed that at-HBP was successfully grafted onto the fabric surface. Dyed with reactive dye C.I. reactive Blue 4, the color strength of the at-HBP-modified fabric was enhanced, even when dyeing was carried out without the electrolyte. The washing and rubbing fastness of the salt-free dyeing of fabrics was also good compared with those obtained by conventional dyeing. The adsorption isotherm of C.I. reactive Blue 4 on modified fabric was examined and found to follow a Langmuir-type adsorption model. The at-HBP modification mechanism of ramie fabric and dyeing mechanism with reactive dye were suggested.     

Synthesis,characterization, and properties of antibacterial dye based on chitosan

A new low-molecular-weight antibacterial dye was obtained by reaction of Reactive Blue 19 and chitosan previously hydrolyzed with H₂O₂. The compounds were characterized by Fourier-transform infrared spectroscopy, ¹³C solid-state nuclear magnetic resonance, X-ray photoelectron spectroscopy, X-ray diffraction analysis, and antibacterial, solubility, and dyeing performance tests including color difference and fastness. The results show that chitosan dyes were generated with covalent bonds between carbon and nitrogen atoms via reaction of alkene group of dye and primary amine group of chitosan. According to solubility tests, the solubility of the chitosan dye was controlled by the molecular weight of chitosan. In addition, compared with Reactive Blue 19, the antibacterial property of the chitosan dye was increased against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Besides, chitosan dye demonstrated better lightfastness and waterfastness than the original dye. Therefore, chitosan dye provides a new perspective for improving decorative and antimicrobial properties of wood products.     

An attempt of improving polyester inkjet printing performance by surface modification using β‐cyclodextrin

To improve the sharpness and the color yield of polyester fabrics with water‐based pigment inkjet printing, surface modification was proceeded using β‐cyclodextrin and citric acid. Fabrics were modified in the solution of β‐cyclodextrin with the concentration 100g/L and citric acid 100g/L. The line width and image area of printed patterns, which could evaluate the printing performances, on the modified polyester fabric were decreased by 77% and 62% in comparison with that of the control, respectively. The color yield characterized by the K/S value was enhanced by 47%. Scanning electron microscope and atomic force microscope images confirmed that the capillary effect was decreased and the surface roughness was increased after the surface modification. The microscope images of the printed patterns clearly showed that the sharpness and the color yield were improved. Thereby, β‐cyclodextrin modification offered a potential way to polyester pretreatment for pigment inkjet printing. Copyright © 2012 John Wiley & Sons, Ltd.     

Friction and wear properties of combined surface modified carbon fabric reinforced phenolic composites

Carbon fabric (CF) was surface treated with silane-coupling agent modification, HNO₃ oxidation, combined surface treatment, respectively. The friction and wear properties of the carbon fabric reinforced phenolic composites (CFP), sliding against GCr15 steel rings, were investigated on an M-2000 model ring-on-block test rig. Experimental results revealed that combined surface treatment largely reduced the friction and wear of the CFP composites. Scanning electron microscope (SEM) investigation of the worn surfaces of the CFP composites showed that combined surface modified CFP composite had the strongest interfacial adhesion and the smoothest worn surface under given load and sliding rate. SEM and X-ray photoelectron spectroscopy (XPS) study of carbon fiber surface showed that the fiber surface became rougher and the oxygen concentration increased greatly after combined surface treatment, which improved the adhesion between the fiber and the phenolic resin matrix and hence to improve the friction-reduction and anti-wear properties of the CFP composite.     

Study the effect of metal ion on wool fabric dyeing with tea as natural dye

Aqueous extract of natural dye, tea was dyed on the wool fabric with dark brown for 2% and 5% shade. The tea containing tannins as the main colorant species to produce different shade with different mordant salts. The mordant salts Alum, CuSO₄, FeSO₄, ZnSO₄, Na₂SO₄, and MgSO₄ were used to dye fabric using three different dyeing methods: pre-mordanting, meta-mordanting and post-mordanting. The color of the fabric was investigated on Data Color matching system in terms of K/S and CIE Lab-color difference values. The post-mordanting method gave the great depth of shade of natural dye tea with 2% and 5% shade, it also give good light fastness and wash fastness properties. Copper was found as a good mordant to achieve the best results with transition metal ions effect. Deep shades (K/S = 17.50) were obtained for original sample of 5% with color difference ΔE value is 0.17, as compare to 2% original sample of tea of light brown shades (K/S = 10.50) with color difference ΔE value is 0.50 under maintained temperature at 85 °C for 35 min of dyeing.     

An evaluation of the dyeing behavior of sol–gel silica doped with direct dyes

A new dyeing process of sol–gel silica doped with direct dyes is investigated for improving color strength (K/S value) and dyeing fastness. Cotton fabrics are dyed in this direct dye silica solution. The results indicate that the K/S value of C.I. Direct Blue 86 and C.I. Direct Red 23 are enhanced by 12.8% and 16.8%, respectively. For C.I. Direct Blue 86, the washing staining fastness is improved by half a grade, and the rubbing fastness and the washing change fastness are enhanced by one grade, respectively. Compared to the fabric fixed with fixing reagent MMF-1, the K/S value is improved by about 23.7% and the wet rubbing fastness and washing change fastness are enhanced by half a grade. The formation of uniform continuous layers on the fiber surface dyed with direct dye silica solution is revealed by video microscope, and the calculated sol–gel weight gain on the fabric is 4.6%.     

Regenerable Fe3O4-decorated chitosan/carboxymethyl cellulose hollow spheres for adsorption and catalytic degradation of dyes

Biopolymer hollow spheres have shown great promise for wastewater treatment due to their unique structure and properties. However, challenging issues like low efficiency and poor recyclability still exist for most hollow spheres. In this study, the modification of chitosan/carboxymethyl cellulose (CS/CMC) with Fe₃O₄ nanoparticles for the formation of bifunctional CS/CMC-Fe₃O₄ hybrid hollow spheres were prepared using a facile two stage mixing route, which exhibited excellent adsorption and catalytic degradation of dyes. The removal ability of the synthesized hollow spheres towards acid blue-113 (AB) and reactive orange C-3R (RO) using persulfate oxidation system was greatly improved compared with single adsorption or catalysis. The removal ratio of AB and RO could reach up to 96.2 and 97.5%, respectively. The kinetic process conformed to the quasi-second-order kinetics and the adsorption process was the controlling step of dye removal. In addition, the created hollow spheres showed excellent environmental adaptability and regenerative capability. This study provides a convenient and practical method for catalyst loading on biomass hollow spheres, which has perspective applications in wastewater purification.

     

Regioselective synthesis and biological activity of oxidized chitosan derivatives

Oxidized chitosan derivatives with various degrees of oxidation (DS, 0.1–1.0) were prepared by the treatment of chitosan with CrO₃/aq HClO₄ or by the oxidation of ­3‐O‐ and N‐protected chitosan with 30% aq H₂O₂/Na₂WO₄ followed by 3‐O‐ and N‐deprotection. The oxidized products were then N‐acetylated with Ac₂O in order to improve their water‐solubility. Although the oxidized chitosan derivative of DS 0.28 and the degree of N‐acetylation of chitosan (DA) 38% was insoluble in the pH 3–8 region, that of DS 0.26 and DA 76% was soluble in the neutral pH range. The newly‐prepared acetylated and oxidized chitosan derivatives were found to suppress the chemiluminescence response of inflammatory cells such as canine polymorphonuclear cells (PMNs). Analysis by the surface plasmon resonance method revealed that the bind and release behavior of PMNs to acetylated oxidized chitosan derivatives was similar to that against carboxymethylated chitosan derivatives. The amount of water‐soluble chitosan derivative bound to cytokine IL‐8 was found to be affected by the structural and electronic features of the chitosan substituents in the chitosan chain. Copyright © 2003 John Wiley & Sons, Ltd.     

Adsorption rate of Reactive Black 5 on chitosan based materials: geometry and swelling effects

The overall adsorption rate of Reactive Black 5 dye (RB5) on chitosan based materials was elucidated using diffusional models. Fundamental aspects, such as, geometry of the adsorbents and swelling effects were considered. Chitosan based materials (powder and film) were prepared from shrimp wastes and characterized regarding to the fundamental features for adsorption. Experimental decay curves were obtained under different conditions of stirring rate and initial dye concentration. The data were modeled according to the external mass transfer and diffusional models. The k_L (external mass transfer coefficient), D_ep (effective pore diffusion coefficient) and D_s (surface diffusion coefficient) values were estimated. For both adsorbents, it was found that the surface diffusion was the intraparticle diffusion mechanism governing the adsorption rate of RB5, since its contribution was higher than 92 % regardless the position and time. The D_s values ranged from 2.85 × 10^?11 to 5.78 × 10^?11 for chitosan powder and from 4.15 × 10^?11 to 12.12 × 10^?11 cm² s^?1 for chitosan films. The RB5 adsorption was faster when chitosan powder was used, mainly at higher stirring rates and initial dye concentrations. The swelling effect was most pronounced for the chitosan films, where, provided an increase of about 65 times in the D_s value.     

Preparation of the water-soluble chitosan-coated oxidized regenerated cellulose gauze

A water-soluble chitosan-coated oxidized regenerated cellulose (ORC) gauze was prepared by the oxidation of a viscose gauze with NO₂/CCl₄ and subsequent treatment with a solution of chitosan in aqueous acetic acid and finally neutralization with NaOH/C₂H₅OH solution. A series of C6 ORC samples with different –COOH content were prepared and coated by chitosans (CTS) with different molecular weight (Mw) of 2,000, 50,000, 100,000 (denoted as CTS1, CTS2, CTS3). FT-IR and TG suggested the formation of the amide bond between the carboxyl group of ORC and the amino group of CTS. Kjeldahl nitrogen analysis of ORC gauze treated with CTS (CTS-ORC) showed that the percentage of chitosan with the lowest Mw of 2,000 introduced on ORC surface was highest and increased with oxidation time, while chitosans with medium and high Mw showed that the maximum percentage of chitosan introduced on ORC surface occurred at the oxidation time of 8 h. The neutralized chitosan-coated ORC gauze could still maintain its original morphological form and was water-soluble, and could form a transparent gel quickly for 5 s in water. The prepared water-soluble gauze could be anticipated to possess the improved hemostatic and antibacterial properties.     

Effect of Surface Protonation on Device Performance and Dye Stability of Dye-sensitized TiO2 Solar Cell

A flat thin TiO₂ film was employed as the photo-electrode of a dye sensitized solar cell (DSSC), on which only a geometrical mono-layer of dye was attached. The effect of sur-face protonation by HCl chemical treatment on the performance of DSSCs was studied. The results showed that the short-circuit current Jsc increased significantly upon the HCl treatment, while the open-circuit voltage Voc decreased slightly. Compared to the untreated DSSC, the Jsc and energy conversion efficiency was increased by 31% and 25%, respectively, for the 1 mol/L HCl treated cell. TiO₂ surface protonation improved electronic coupling between the chemisorbed dye and the TiO₂ surface, resulting in an enhanced electron in-jection. The decreased open-circuit voltage after TiO₂ surface protonation was mainly due to the TiO₂ conduction band edge downshift and was partially caused by increased electron recombination with the electrolyte. In situ Raman degradation study showed that the dye stability was improved after the TiO₂ surface protonation. The increased dye stability was contributed by the increased electron injection and electron back reaction with the electrolyte under the open-circuit condition.     

Eco-friendly and protective natural dye from red prickly pear (Opuntia Lasiacantha Pfeiffer) plant

New natural dye extracted from red prickly pear was used for dyeing wool with different types of mordents. The effect of mordant concentration on the color strength was discussed; the results obtained indicated that the color strength decreases with the increase of mordant concentration. The effect of the dye bath pH, salt concentration, dyeing temperature and dyeing time was also studied. The color strength and the dye uptake have exhibited high values. Good fastness properties of the dyed fabric were achieved.Antimicrobial activity of wool fabric dyed with this dye was tested according to diffusion agent. Test organisms as Escherichia coli, Bacillus subitilus, Pseudomons aeruginosa and Staphylococcus aureus were used and the results indicated that the samples exhibited a high inhibition zone.According to the available literature, this is the first report concerning a natural dye for fabric from fruits of red prickly pear plants.     

Effects of TiO<Subscript>2</Subscript> on the hydrophilicity of сotton/polyester (50/50) blend fabric under UV irradiation

Alkaline TiO₂ nanoparticles treated cotton/polyester (50/50) blend fabric were prepared, and then exposed to UV irradiation. It was found that the addition of a small amount of TiO₂ nanoparticles to the coating solution improves the hydrophilicity and mechanical strength of the fabrics. The treated fabrics exhibited high water absorption as well as better hydrophilicity compared to the untreated sample. Compared to the surface of untreated blend fabric, scanning electron microscopy showed that the surface of the modified blend fabric becomes rough and covered by a layer of other materials. Furthermore, X-ray diffraction demonstrated the formation of crystalline material. In addition, thermograms showed that the modification process improved the thermostability of blend fabric.     

Cell outer membrane mimetic modification of a cross-linked chitosan surface to improve its hemocompatibility

A novel strategy has been developed to improve the hemocompatibility of chitosan surface by cell outer membrane mimetic structure able to reduce protein adsorption and cell adhesion. Phosphorylcholine dichloride was synthesized and grafted onto a glutaraldehyde-cross-linked chitosan (CS-GA) film surface to prepare phosphorylcholine-coated CS-GA film (CS-GA-PC) through a heterogeneous reaction process. The spectroscopic and contact angle characterization show that a cell outer membrane mimetic structure was formed on the cross-linked chitosan surface, and the significantly improved hemocompatibility of the modified surface was shown by a suppression of 94% on platelet adhesion, a suppression of 60–70% for bovine plasma fibrinogen and bovine serum albumin adsorptions. These results demonstrated that this cell outer membrane mimetic surface modification with phosphorylcholine dichloride is a promising strategy to improve the hemocompatibility of chitosan.     

过渡金属氧化物修饰石墨毡阴极及电催化氧化性能测试

采用H2O2化学预处理石墨毡,并将过渡金属氧化物Ce O2负载到石墨毡上,制备出复合石墨毡阴极材料。研究结果表明H2O2处理可增加石墨毡的含氧官能团,改善表面亲水性,进而提高Ce O2的负载量,XRD分析表明石墨毡表面负载的Ce O2为萤石结构。电化学阻抗谱(EIS)和循环伏安曲线(CV)分析表明修饰后的石墨毡电荷传输阻力变小,氧化还原电流强度显著增强,活性表面积增大8倍,线性扫描(LSV)实验表明改性石墨毡在氧还原过程中具有较大的电流密度,是未改性前的8.5倍。采用改性石墨毡作为阴极,进行电芬顿催化降解甲基橙测试,20 min脱色率达到96.8%,与未改性石墨毡相比,去除率提高133.2%,显著提高了其电催化氧化性能。     

过渡金属氧化物修饰石墨毡阴极及电催化氧化性能测试

采用H₂O₂化学预处理石墨毡,并将过渡金属氧化物CeO₂负载到石墨毡上,制备出复合石墨毡阴极材料。研究结果表明H₂O₂处理可增加石墨毡的含氧官能团,改善表面亲水性,进而提高CeO₂的负载量,XRD分析表明石墨毡表面负载的CeO₂为萤石结构。电化学阻抗谱(EIS)和循环伏安曲线(CV)分析表明修饰后的石墨毡电荷传输阻力变小,氧化还原电流强度显著增强,活性表面积增大8倍,线性扫描(LSV)实验表明改性石墨毡在氧还原过程中具有较大的电流密度,是未改性前的8.5倍。采用改性石墨毡作为阴极,进行电芬顿催化降解甲基橙测试,20 min脱色率达到96.8%,与未改性石墨毡相比,去除率提高133.2%,显著提高了其电催化氧化性能。     

Plasmonic osmium hydrosols: Preparation,characterization, and properties

A simple route for the synthesis of mesoporous and plasmonic chitosan supported osmium hydrosols (Os⁰) has been reported using osmium (III)-sodium borohydride redox reaction at room temperature. The composition and morphology of nanoparticles were determined with XRD, XPS, TEM, EDX, SEM, FTIR and N₂-adsorption desorption techniques. No SPR band of Os⁰ at 485 nm was observed for the same redox reaction with cetyltrimethylammonium bromide (CTAB) for ca. 120 min at room temperature. The surface oxidation of Os⁰ into OsO₂ was detected by XRD and XPS. XRD shows the presence of chitosan onto the surface of nanoparticles. The average pore size, and pore volume were found to be 7.23 nm, and 0.239 cc/g, respectively, for Os⁰. The persulfate activation catalytic activity was tested in situ chemical oxidation of basic red 2 (safranin) under activated and un-activated persulfate. Safranin was adsorbed onto the Os⁰ and complex was formed. The oxidation of dye follows pseudo-first order kinetics (k_app = 14.8 × 10^-3 min⁻¹ at [S₂O₈^2-] = 3.3 mM). The activated system showed a much higher dye oxidation rate compared to either S₂O₈^2- or Os⁰ alone. The activation energy (E_a = 105 kJ/mol) was calculated for the system by using Arrhenius equation. The reaction mechanism of Os⁰ activation of persulfate was elucidated and discussed.     

Silver‐Doped TiO2‐Coated Cotton Fabric as an Effective Photocatalytic System for Dye Decolorization in UV and Visible Light

In this study, titanium tetra‐isopropoxide was used as a precursor of TiO₂ for in situ coating on cotton fabric by sol–gel method. Subsequently, silver nitrate was used as doping agent to prepare silver‐doped TiO₂‐coated cotton fabric during hydrothermal treatment. The treated samples were characterized through field‐emission scanning electron microscopy, energy‐dispersive X‐ray analysis, inductively coupled plasma‐mass spectroscopy and UV–visible absorption spectroscopy to study morphology, composition of deposited elements and light absorption behavior of treated samples. X‐ray photoelectron spectroscopy was carried out to analyze the electronic state of silver in TiO₂‐coated fabric after hydrothermal treatment. Doping of silver on TiO₂‐coated fabric and subsequent hydrothermal treatment was found to enhance dye decolorization rate of rhodamine B dye solution in both UV and visible light radiations with respect to undoped TiO₂. The study shows that an optimal level of silver‐doped TiO₂‐coated fabric can be used repeatedly for dye decolorization without significant loss in its photocatalytic activity. The self‐cleaning properties of samples were also studied using methylene blue as a staining agent. It was observed that the presence of 1.8% silver on the weight of titanium in doped samples provides almost 82% of stain degradation.     

长链双烷基次膦酸作为共吸附剂修饰TiO_2光阳极

对TiO2/染料/电解质界面进行修饰是提高染料敏化太阳电池(DSC)性能的有效手段,其中引入共吸附剂有机小分子和染料共同吸附在TiO2表面是一种简单有效提高DSC性能的方法.本文合成了长链的双正十二烷基次膦酸(DDdPA)作为染料的共吸附剂应用于染料敏化太阳电池.通过红外光谱(FT-IR)表征DDdPA在TiO2表面的吸附;借助电化学阻抗谱(EIS)及强度调制光电流谱(IMPS)/强度调制光电压谱(IMVS)等技术表征了电子的传输与复合动力学过程.研究发现,DDdPA可以很好地与染料共同吸附在TiO2表面;与二(3,3-二甲基丁基)次膦酸(DINHOP)相比,DDdPA的引入可以更好地抑制TiO2/染料/电解质界面处的电子复合;在优化浓度配比下,DDdPA的引入有效提高了器件的电子寿命,使TiO2导带边负移约30 mV,最终使器件的开路电压提高了47 mV,光电转换效率提升约10%.