聚乙烯醇/碳纳米管复合超滤膜的制备及应用研究

以聚乙烯醇(PVA)为基膜材料,以羧基化碳纳米管(c-CNT)为添加剂,采用浸没沉淀相转化法制备了一种新颖的PVA/c-CNT复合超滤膜.考察了c-CNT的用量对膜力学性能、水通量、截留率及耐污染性能的影响.结果表明,当c-CNT用量为2份时,复合超滤膜的拉伸性能、水通量、截留率均达到最佳,膜的抗污染能力得到提高.分别...     

Preparation of poly (acrylic acid) containing core‐shell type resin for removal of basic dyes

BACKGROUND: A core‐shell type carboxylic acid modified resin was prepared and dye sorption characteristics of the resin were investigated. The resulting grafted resin material has been shown to be an efficient sorbent for removal of basic dyes from water as a result of the carboxylic acid group's affinity towards basic dye molecules. RESULTS: The resin was characterized using Fourier transform infrared spectroscopy (FT‐IR) and titrimetric methods. The basic dyes (methylene blue and crystal violet) were removed by contacting the swollen resin with aqueous dye solutions at room temperature. The adsorption capacities of resin were determined by colorimetric analysis of the residual dye content in the adsorption medium, which gave capacities for methylene blue and crystal violet of 300 and 250 mg g^?1 resin, respectively. The prepared resin is also able to remove basic dyes completely from dilute aqueous dye solutions. Batch kinetic sorption experiments determined that a pseudo‐second‐order rate kinetic model was applicable. CONCLUSION: Flexibility of the polymer side chains is expected to provide pseudo‐homogeneous reaction conditions and easy accessibility of the functional groups involved. The adsorbents are expected to have the advantage of mobility of the grafted chains in the removal of basic dyes from aqueous mixtures. The resin has potential as an adsorbent for removal of basic dyes for use over a wide pH range. Copyright © 2011 Society of Chemical Industry     

Liposomes of phosphatidylcholine: a biological natural surfactant as a dispersing agent

Disperse dyes are very hydrophobic molecules that in their commercial form are usually milled in the presence of large amounts of dispersing agents (synthetic surfactants). Other dispersing agents are added as auxiliaries during the dyeing process. These synthetic surfactants were substituted for liposomes prepared with phosphatidylcholine, a well-known biological surfactant of natural origin which is environmentally friendly, and liposomes were studied as a dispersing agent in polyester dyeing.
The physicochemical behaviour of dye dispersion was analysed by two experimental measurements: the aggregation process of dye particles by filtration of dispersion and the determination of the turbidity ratio. The results obtained show the usefulness of liposomes as a dispersing auxiliary in a dyeing process, avoiding aggregation of dye molecules at high temperatures. Moreover, polyester dyeing shows similar final exhaustions, approximately 90%, at different kinetics, when liposomes are used.     

Developing chromic dyeable PET nanocomposites: The dye absorption and complex formation mechanisms

This research aimed to investigate the possibility of enhancement of polyethylene terephthalate (PET) dyeability using nanotechnology. Different kinds of disperse, acidic, and chromic dyes were used for dyeing of produced PET/silver nanocomposite fine multifilament yarns produced at the take up speeds of 3000 m min⁻¹ and their prepared fabrics. Dyeability improved by using acidic dyes. However, the more promotion effect was achieved by chromic dyes. No effect on absorption of disperse dyes revealed that no physical effect can be considered for dye absorption. The electrostatic interaction between silver and acidic dye molecules and forming the coordinative bonds with chromic dye molecules on nanocomposite yarns and fabrics were concluded and thoroughly discussed. Applying chromic dye with the more potential of creating coordinative bonds intensified the improvement of dyeability. Optimized silver ratio for the dyeability enhancement was affected by the mechanisms of dye absorptions discussed and proven by investigating dye concentrations in the effluent baths after the dyeing processes. It has been found that the steric hindrance is the key factor for absorption of chromic dyes; however, it is different in the case of acidic dyes, well discussed according to the dye absorptions mechanisms. The results can be also considered as evidence to prove forming the coordinative bonds with chromic dye molecules. This has also been confirmed by appearing a bathochromic shift in the absorption peaks by increasing dyeability using chromic dye. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

含羧甲磺酰基水溶性分散染料的研究

本文提出一类含有羧甲磺酰基（—SO_2CH_2COOH）的新的水溶性分散染料。利用应用时的高温,它转变为不溶性的分散染料。因此,在成品加工时不必进行砂磨,不需要扩散剂。它在弱酸、中性和碱性中都可使用,并适用于纯涤纶和涤/棉织物的印花和轧染。     

水溶性染料与有机颜料商品化技术的助剂应用(续)

水溶性染料中的活性染料和酸性染料提高冷水中的溶解度,有机颜料水性表面改性处理都涉及助剂的应用,是染料和颜料商品化技术的一部份。液状染料的生产和颜料喷墨印墨的制备,都与之有关联。本文以润湿、分散的基本原理为指导设计专用助剂的化学结构,并用于生产实际进行基础性研究。     

The surface acidity of acid oxidised multi-walled carbon nanotubes and the influence of in-situ generated fulvic acids on their stability in aqueous dispersions

The oxidation of multi-walled carbon nanotubes (MWCNTs) with nitric acid was studied. In addition to the formation of oxygen-containing surface functional groups, the oxidative digestion of graphene caps and layers generated polycyclic aromatic substances, classified as fulvic acids (FAs). The latter remained immobilised on the MWCNT surface in acidic and neutral solutions but were released in basic pH solutions, which were subsequently separated, purified and characterised by high-performance liquid chromatography and mass spectrometry. Using acid-base titrations, the number of surface acidic functional groups was determined, which was shown to significantly decrease after FAs were removed. Depending on the length of oxidation, FAs account for up to 43% of the surface acidity of MWCNTs. The protonated solubilised fulvic acids can be readsorbed on the surface of oxidised or unfunctionalised MWCNTs, which assists the stability of carbon nanotube suspensions in the aqueous phase.     

Probing speciation inside a conducting polymer matrix by in situ spectroelectrochemistry

The interactions between polypyrrole and an embedded bromophenol blue (BPB) dye at different oxidation levels and pHs were investigated. Cyclic Voltammetry, in situ UV–vis and Raman spectroelectrochemistry were used to detect electrochemical and optical changes in the BPB-doped ppy films. The acid–base equilibrium of the embedded dye was observed to be highly dependent on the applied potential and on the pH conditions. The intensities of the vibrational bands characteristic of the acidic and basic forms of the species inside the film clearly showed a potential dependent shift of the dissociation equilibrium of BPB, which is effectively controlled by the oxidation level of ppy. This type of information provides some insights into the effect of the environment on the chemical behavior of acid–base pairs embedded in polymeric matrixes.     

涤纶长丝染色不匀的原因及解决方法

涤纶长丝染色不匀一般由于其结构原因，缺少亲水基因。并且与其生产的其它因素有关。解决方法也根据这两方面原因来改善，严格控制聚酯切片质量、熔体质量、侧吹风条件及油剂的性能、丝条的含油率、上油方式都是根据其结构原因；与其他因素有关系的如：升温过快、保温时间太短、布的循环速度过缓、燃料吸附不均匀、布容量远远超过标准容量。其防治方法：合理确定升温时间和保温时间，重新调整喷嘴压力；重新选择喷嘴隙缝及圆锥管以增加布速；合理选择染化料，拼色中如选用上染速率相差较大的分散染料，则应适当地增加分散剂或染料；容布量适中。     

Removal of Acidic and Basic Dyes from Water using Crosslinked Polystyrene Based Quaternary Ethyl Piperazine Resin

In this study, a beaded polymer with quaternary amine functions was prepared in two steps, starting from poly (vinyl benzyl chloride-ethylene glycol dimethacrylate) (PVBC) based beads, according to the synthetic protocol; modification of ethyl piperazine with PVBC (EP-PS), and quaternization of ethylpiperazine modified beads with chloroacetic acid (QEP-PS). The QEP-PS resin was used for the removal of reactive red 120 as an acidic dye and malachite green chloride as a basic dye. Dye extraction experiments were carried out simply by contacting wetted sorbent samples with aqueous dye solutions at room temperature. Capacities were determined by colorimetric analysis of the residual dye contents. The resin showed that reasonable high dye sorption capacity (0.34-0.41 g per gram of dry resin) was achieved. The adsorption conditions (initial dye concentration and pH) were varied to evaluate the mechanism of adsorption of both basic dyes and acidic dyes on the prepared resin. This material is also able to remove both the anionic dye and cationic dyes completely even from highly diluted aqueous dye solutions.     

The effect of dispersants on the tensile properties of carbon nanotube/vinyl ester composites

The effects of eight different dispersants on the stability of multiwalled carbon nanotubes (MWCNTs) in vinyl ester (VE) resin systems have been systematically analyzed. Suspensions incorporating different amounts of dispersants relative to the concentration of MWCNTs in the VE have been prepared. The resistance to sedimentation of MWCNTs in the resin was investigated by using a centrifugation technique. One dispersing agent (B60H) was found to impart long‐term stability to suspensions of MWCNTs in VE. VE‐based composites reinforced with MWCNTs were prepared using different amounts of the dispersing agent. Tensile tests were performed to analyze the effect of different concentrations of MWCNTs and the use of the dispersing agent in the composites. Fracture surfaces of VE nanocomposites have been analyzed using scanning electron microscopy (SEM) to elucidate the reinforcing effect of the CNTs. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

The adsorption of malachite green (MG) as a cationic dye onto functionalized multi walled carbon nanotubes

Synthetic dyes are widely used by several industries to color their products. The discharge of colored wastewater into the hydrosphere causes serious environmental problems. We used functionalized multi wall carbon nanotubes as an adsorbent for the adsorption of cationic dye, malachite green, from aqueous solution. Based on information provided by the Iranian Research Institute of Petroleum Industry, carbon nanotubes are produced using a chemical vapor deposition (CVD) technique. These as-received MWCNTs were functionalized by acid treatment. The remaining dye concentration was read by UV-visible absorption spectroscopy at maximum adsorption wavelength. The effect of different operational parameters such as contact time, pH of solution, adsorbent dose and initial dye concentration were studied. The results showed that by increasing of contact time, pH and adsorbent dose the removal of dye increased, but by increasing initial dye concentration, the removal efficiency decreased. Adsorption isotherms and kinetics behavior of f-MWCNTs for removal of malachite green was analyzed, and fitted to various existing models. The experimental data were well correlated with the Langmuir isotherm with a maximum adsorption capacity (q _m ) and regression coefficient (R²) of 142.85 mg/g and 0.997, respectively. The results of this study indicate that functionalized multi wall carbon nanotubes can be used as an effective adsorbent for the removal of dyes.     

The Solubilization of Disperse Dyes by Dispersing Agents at 127°C

The solubilities in water at 127°C of eight disperse dyes of various structures have been determined, as well as the effect of eleven different dispersing agents on the solubilization of these dyes. A special cell was designed for these experiments. While the solubilities of six of the eight dyes are similar and those of the remaining two larger by approximately one order, solubilization by dispersing agents covers a wide range of values. No clear pattern of dye-dispersing agent interaction has emerged from the work, especially with regard to the effects of dye structure, and a more detailed investigation is therefore being undertaken.     

A Study of the Reactions of Reactive Dyes with Wool under Industrial Dyeing Conditions

The extent of reaction with wool of five representative reactive dyes (having different reactive groups) has been determined at two depths of dyeing (0.5% and 3%) under conditions of dyeing recommended by the manufacturers. The covalent bonding of the dye to the reactive groups of the fibre was determined by analytical techniques based on the use of fdnb (1-fluoro-2,4-dinitrobenzene). It has been shown that these and other similar techniques may introduce fundamental errors in the estimation of basic groups covalently bound. The results indicate that, under the acidic conditions recommended, the role of the basic group in keratin is less significant than previously reported. By application of correction factors, a stoichiometric relation has been obtained between the amount of dye molecules bound and the number of reactive groups in the fibre which are blocked.     

Dyeing of chemically modified cellulose. IV. Dyeing of oxidized celluloses with some reactive and direct dyes

Oxidation of cotton cellulose with potassium periodate, potassium dichromate-sulfuric acid, and potassium dichromate-oxalic acid results in creation of variable amounts of acidic and reducing groups along the cellulose molecule, being dependent upon the type of oxidizing agent used. Such groups were found to have a profound effect on the acceptability of cellulose for reactive and direct dyes. The rate and extent of dye uptake for the oxidized celluloses were significantly lower than those of the unoxidized cellulose. While presence of the acidic groups in cellulose molecules induces a negative environment thereby making approach of the dye anions to the cellulose difficult, presence of the reducing groups lowers the magnitude of cellulose reactivity as well as decreasing its adsorptive power. Further modification of the oxidized celluloses via either borohydride or chlorous acid treatment brought about modified celluloses the dyeability of which confirms the inhibiting effect of the acidic and reducing groups of those oxidized celluloses on the rate and extent of dyeing with reactive and direct dyes.     

Aqueous dispersion of surfactant-modified multiwalled carbon nanotubes and their application as an antibacterial agent

The dispersing power of different surfactant-modified multiwalled carbon nanotubes (MWCNTs) and their effect on the antibacterial activity were examined. Three surfactants, including hexadecyltrimethylammonium bromide (CTAB), triton X-100 (TX-100) and sodium dodecyl sulfate (SDS) were tested. UV–vis absorbance, transmission electron microscopy and Fourier transform infrared spectroscopy were used to characterize the dispersion of MWCNTs in the aqueous phase, showing that the surfactant molecules had been adsorbed onto the MWCNTs’ surface. Among the three surfactants, TX-100 and CTAB provided maximum and minimum dispersion, respectively. The surfactant-modified MWCNTs exhibited different antibacterial activities to Streptococcus mutans. The fluorescence images showed that the surfactant-modified MWCNTs were not only capable of capturing bacteria and forming cell aggregates, but also killing them. Under the same concentration and treatment time, the CTAB-modified MWCNTs exhibited the strongest antibacterial activity compared to the TX-100 and SDS-modified MWCNTs. The optical density growth curves and viable cell number determined by the plating method suggested that the antibacterial activity of all surfactant-modified MWCNTs was both concentration- and treatment time-dependent.     

Improved dispersibility of multi‐wall carbon nanotubes with reversible addition–fragmentation chain transfer polymer modification

A non‐covalent approach is used to modify multi‐wall carbon nanotubes (MWCNTs) via a block polymer that can be synthesized in aqueous solvent through reversible addition–fragmentation chain transfer polymerization. The block polymer consists of oligo(ethylene glycol) methyl ether acrylate and acrylic acid. The hydrophobic backbone is significantly adsorbed on hydrophobic MWCNT surfaces, which is verified using transmission electron microscopy, thermogravimetric analysis and X‐ray photoelectron spectroscopy. The coated block polymer can prevent the aggregation of MWCNTs and improve their dispersibility in water. The MWCNTs after modification are stable in water even after standing in a long‐term test. © 2015 Society of Chemical Industry     

Graphene oxide–TiO2 composite filtration membranes and their potential application for water purification

Graphene oxide-particle composite films with filtration function have been successfully synthesized by a two-step method. First, graphene oxide–TiO₂ composite sheets are prepared, which can form stable dispersion in water. Then, by assembling these composite sheets, graphene oxide–TiO₂ films are obtained. In these as-prepared films, dilated space and channels are desirably formed by introducing nanoparticles between these carbon sheets, making them promising separation membranes. We used these films as filtration membranes to remove dye molecules (methyl orange and rhodamine B) from water. The results show that apart from the adsorption capacities of these dyes, these graphene oxide–TiO₂ films can also capture additional amount of dye molecules, indicating their potential applications in water purification areas.     

Effect of Dispersed Multi-Walled Carbon Nanotubes on Mixed Matrix Membrane for O2/N2 Separation

Mixed matrix membranes (MMMs) consisting of multiwalled carbon nanotubes (MWCNTs) embedded within polyetherimide were prepared. Surfactants of different charges were utilized to disperse the nanotubes through a simple non-covalent approach. The characterization results suggest that proper selection of the dispersing agent contributed to better dispersion of nanotubes. The MMMs exhibited improved thermal stability and mechanical strength, which indicate the improvement of dispersion and compatibility within the polymer matrix. The resulting membrane exhibited permeance improvement of O₂ and N₂ as much as 87.7% and 120% respectively compared to that of neat polyetherimide. The results implied that Triton-X100 treated MWCNTs is a promising filler to enhance gas permeability.     

A novel nonchemical approach to the expansion of halloysite nanotubes and their uses in chitosan composite hydrogels for broad‐spectrum dye adsorption capacity

A novel method based on cryoscopic expansion of halloysite nanotubes via frozen water molecules entrapped in their lumens and subsequent lyophilization was described. Detailed analyses confirmed that the inner and outer diameters as well as the surface area of the nanotubes could be efficiently increased without disturbing the inherent tubular structure. The benefits of cryo‐expanded nanotubes for the enhancement of chitosan hydrogel performances were discussed. The composite hydrogels, depending on their compositions and morphologies, exhibited significantly enhanced swelling and mechanical properties compared with neat chitosan hydrogel. This effect was even more pronounced in the hydrogels containing cryo‐expanded halloysite nanotubes. Although neat chitosan is a selectively good adsorbent for anionic dyes, in the presence of a small amount of cryo‐expanded halloysite, the resultant composite hydrogel can establish a relatively high adsorption capacity for anionic and cationic dyes as a broad‐spectrum dye adsorbent. POLYM. COMPOS., 37:2770–2781, 2016. © 2015 Society of Plastics Engineers