Adsorption study of nonionic surfactants on polyester fibers

An adsorption study of a series of nonionic surfactants on polyester fiber was performed to determine the relative importance of sub-strate affinity in the detergency process. The fiber used in this study was a multifilament polyester yarn. Because of the relatively low surface area/g of the yarn, analytical methods for detecting the depletion of surfactant due to adsorption have to be extremely sensitive. One qualitative technique used was streaming potential measurements. The electrokinetic effect, which the streaming poten-tial measures, depends on the nature of the electrical double layer at the fiber/solution interface. The modification of the streaming potential indicates that the extent of surfactant adsorption onto the fiber surface is very similar for the nonionic surfactants studied. A very sensitive, quantitative analytical technique, which can only be used for surfactants with an appropriate chromophore, is ultraviolet (UV) spectroscopy. The UV study showed that the adsorption of the nonylphenol ethoxylate onto the polyester is Langmuirian with the adsorption plateau occurring at the critical micelle concentra-tion. For alcohol ethoxylates without a UV chromophore, con-venient quantification at the ppm level represents a difficult analyt-ical problem. In this work, total carbon analysis was developed as a sensitive analytical tool for surfactant determination. Agreement between the UV and total carbon data for the nonylphenol ethox-ylate was quite good. The relevance of the data to the detergency process is discussed.     

The role of porosity in polyethylenimine adsorption onto cellulosic fibers

The total adsorption of a given polyethylenimine on pulp fibers, the porosity of which was altered by different drying conditions, was determined and compared with the available internal surface of the fibers. Since polymer adsorption takes place in an aqueous environment, the pore volume and the internal surface of pores as a function of their size were determined from a first benzene desorption isotherm, measured on fibers in which water was replaced by benzene to preserve their swollen structure. The total adsorption of a given polyethylenimine was found to be in a direct relation to the internal surface available in pores larger than a certain size, regardless of the total porosity. Consequently, it is concluded that the adsorption capacity is determined by the accessible surface.     

水溶性改性纤维素对粘土水化的抑制作用

为探索水溶性改性纤维素聚合物作为钻井用页岩水化抑制剂的可能性，本文以工业棉纤维为基本原料，在会成条件相当的情况下制备了羧甲基纤维素钠（CMC－Na）、羧甲基纤维素钾（CMC－K）、阳离子化羧甲基纤维素钠（CCMC－Na）与阳离子化波甲基纤维素钾（CCMC－K）四种结构不同的水溶性改性纤维素聚合物；以X-射线衍射、膨胀性试验及造浆试验考察了它们对粘土水化的抑制作用和机理。研究表明，在本试验条件下，四种改性纤维素聚合物对粘土水化均有一定的抑制效果；而合成时引入钾离子或季接阳离子则可使产物的抑制能力明显增强．     

Fibrillation tendency of cellulosic fibers,part 6: Effects of treatments with additive polymers

The influences of the treatments with various polymers on fibrillation and abrasion resistances of lyocell materials were investigated with respect to the type of polymer, the polymer concentration, and the drying temperature. Fibril number, generated with agitation using ball‐bearings (FN_ball), was decreased with increasing the concentration of aminofunctional polysiloxane because of reduction in water retention capacity (WRV) in fibers. The never‐dried lyocell fiber showed smaller decrease in FN_ball because of its higher WRV when compared to dried fibers. The treatment with aminofunctional polysiloxane enhanced not only the fibrillation resistance but also abrasion resistance, which was indicated as rotation number of abrasive bar in the abrasion test (RN_abr). No fibrillation was obtained in the fiber treated with 10 g/L aminofunctional polysiloxane at 120°C for 20 min, while the fibers treated at 60 and 170°C for 15 min were fibrillated in the agitation and abrasion tests. The addition of secondary polyethylene derivative also reduced the fibrillation tendency of lyocell; however, the extent of the reduction was lesser when compared with aminofunctional polysiloxane. The treatments with polyacrylate, polyurethane, and polyisocyanate derivatives improved the fibrillation resistance in lyocell fabrics, while fiber abrasion resistance was not significantly improved by the treatment with those additives, except in polyisocyanate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4140–4147, 2006     

π-Stacking of rhodamine B onto water-soluble polymers containing aromatic groups

Evidences of the π-stacking of rhodamine B onto poly(sodium 4-styrenesulfonate) are given by ¹H NMR spectroscopy. As a consequence of these π-π interactions, changes on the diafiltration and UV-vis absorbance and fluorescence patterns are shown comparing water-soluble polymers containing aromatic rings as poly(sodium 4-styrenesulfonate) and poly(N-methacryloyl-5-aminosalicylic acid) with other polyanions that do not contain aromatic rings as poly(sodium vinylsulfonate) and poly(acrylic acid).     

含氮超交联聚合物对磺胺二甲基嘧啶的吸附

通过一步法制备了一种含氮超交联吸附剂,探究了对水中磺胺二甲基嘧啶的去除能力,通过扫描电镜和红外光谱对超交联聚合物的表面结构和化学性质进行表征。结果表明,该吸附剂的最大吸附容量能够高达336.45 mg/g;吸附动力学过程符合准二级模型。     

Disorder in cellulosic fibers

Ruland's concept of an isotropic disorder function is applied to estimate the disorder parameter and the degree of crystallinity in a few cellulosic fibers: two cottons, native ramie, and a high-tenacity rayon. The results indicate an increase in disorder without any change in crystallinity on mercerization of native celluloses. On hydrolysis, with or without a pretreatment of mercerization, the samples exhibit a higher crystallinity, disorder remaining the same as for native celluloses. A ball-milled sample of “amorphous” cellulose is still found to be fairly crystalline with the lowest disorder. On being wetted in water and oven-dried, a distorted form of cellulose II with higher crystallinity and disorder was obtained. The polynosic fiber, Tufcel, has low values for the degree of crystallinity, disorder parameter, as well as crystallite dimension. A strong dependence of the degree of crystallinity on the crystallite size, particularly the lateral, is observed.     

Properties of henequen cellulosic fibers

The physical properties, thermal stability, and interaction with liquids of cellulosic fibers isolated from henequen fibers (Agave fourcroydes) by an alkaline digestion process were determined. Physical dimensions, apparent length, and diameter of henequen cellulosic fibers were determined by optical microscopy in a random sample of 125 fibers. Other properties such as crystallinity, specific gravity, and cellulose type were also determined. The sorption of several liquids in these cellulosic fibers was measured and correlated to the polar and hydrogen bonding components of the solubility parameters of the liquids. The results show that, in general, henequen cellulosic fibers have properties that are in close agreement with those found in other cellulosic materials from natural sources. © 1995 John Wiley & Sons, Inc.     

Cerium-initiated grafting of acrylonitrile onto cellulosic materials

Grafting of acrylonitrile onto native cotton, swollen cotton, viscose, ramie, and hydrocellulose was studied with tetravalent cerium as initiator. The effect of temperature on the graft yields is examined. With ceric ammonium nitrate the grafting yields are found to be higher at 20 and 40 than at 60°C. Ceric ammonium sulfate, on the other hand, produces more grafting at 60 than at 20 and 40°C. The consumption of ceric ions is less, whereas the per cent graft yields are higher for the swollen cottons and viscose than for native cotton. Graft yields are shown to be related to substrate accessibility if the grafting reaction is carried out under conditions that suppress homopolymerization. Oxidation of these celluloses with Ce^IV has also been studied. It is found that more Ce^IV is consumed during grafting than during oxidation of cellulose under identical reaction conditions. Excess Ce^IV consumed in the grafting reaction has been shown to be directly related to extent of homopolymerization, which accompanies grafting. Some data on the storage stability of the free-radical activity produced by oxidation of cellulose with Ce^IV are also reported. It is observed that the cerium-oxidized samples can initiate graft poly merization even after 4–5 hr. if stored in nitrogen.     

Adsorption and desorption dynamics of associative polymers onto particulates of titanium dioxide,alumina and quartz

The authors have been investigating the adsorption and desorption dynamics of nonionic water soluble polymers on inorganic particles. The influence of the nature of polymers with and without associating hydrophobic end groups, the nature of adsorbents [TiO₂, Al₂O₃ (neutral, acid and basic), and SiO₂], polymer concentrations, linear velocity of fluids, and mutual diffusion of polymer molecules on the patterns of adsorption and desorption distribution of polymer concentrations are shown. The model polymer is a nonionic polyurethane polymer based on ethylene oxide. The polymer's structure is R-O-(DI-PEO)₆-DI-O-R (R is C₁₆H₃₃, DI is isophorone diisocyanate, and PEO is CARBOWAX^TM with a molecular weight of 8200). The phenomenological models of association and dissociation kinetics of associative polymers are suggested. The half-lives of clusters into adsorption and desorption layers are estimated. It is shown that heats of desorption of associative polymers are dependent essentially on heats of dissociation of clusters.     

Adsorption behavior of monomers and formation of conducting polymers on polyester fibers

In situ adsorption of monomers on fibers plays a key role in fabricating highly conductive polyaniline (PANI)‐based textiles by two‐stage oxidation polymerization. Experiments were conducted in aniline monomer and hydrochloric acid solution with the variables such as contact time, initial concentration, and temperature, which can enhance the equilibrium adsorption capacity to aniline of poly(ethylene terephthalate) (PET) fibers. Equilibrium data were fit well by a Henry partition‐type isotherm equation. It was found that the kinetics of the adsorption of aniline onto PET fibers at different operating conditions was best described by the pseudo‐second‐order model. The rate parameters of the intraparticle diffusion model for adsorption were also evaluated and compared to identify the adsorption mechanisms. The monomer exhaustion increased with increasing the temperature. The value of electrical surface resistance of conductive textiles about 3.2 kΩ was obtained when the padder squeeze step was introduced, and the molar ratio of 0.6 between the oxidant concentration and the exhausted concentration of monomers at the adsorption equilibrium was applied. Scanning electron micrographs of PANI/PET composite surfaces were observed, conforming that smooth films were produced by surface polymerization of aniline monomers adsorbed previously on fibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Adsorption of lactic acid onto three ionic liquid‐modified porous polymers

Three ionic liquid (IL)‐modified porous polymers were synthesized and used for the adsorption of lactic acid. The experimental adsorption kinetics and equilibrium data from the IL‐modified polymers were obtained. The kinetic study revealed a low temperature to be advantageous to the adsorption process. The dependence of the level of lactic acid adsorption on the amount of polymer, initial lactic acid concentration, and pH was examined at equilibrium. The maximum efficiency was obtained using the maximum adsorbent dose. A comparison of lactic acid adsorption at different pH revealed anion exchange to be the main interaction between the lactic acid and polymers, not molecular adsorption. The amounts adsorbed were fitted to the Langmuir, Freundlich, and Temkin equations. The equilibrium data for modified polymers (imidazole modified polymer, methylimidazole modified polymer, and ethylimidazole modified polymer) were best represented by the Langmuir and Freundlich isotherm with R² values of 0.99. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Adsorption of nitrate onto nitrogen-doped activated carbon fibers prepared by chemical vapor deposition

Nitrogen-doped activated carbon fibers (ACFs) were prepared by chemical vapor deposition using melamine powder and acetonitrile for introducing quaternary nitrogen on the commercial ACFs, subsequently heated at 950 °C and activated by steam. Adsorption experiments of nitrate in aqueous solution were also conducted to evaluate adsorption capacity of the prepared ACFs using ion chromatography. The amount of introduced nitrogen content and nitrogen species on activated carbon fibers was examined by CHN elemental analyzer and X-ray photoelectron spectroscopy, respectively. As a result, adsorption capacity of quaternary nitrogen-doped ACF (ST-ML-AN-ST) was 0.75 mmol/g, indicating ca. two-times higher than that of untreated ACF (0.38 mmol/g). According to the adsorption data, the Langmuir isotherm model was the best fit. The prepared samples were also regenerated using hydrochloric acid. After regeneration, the adsorption capacity of the nitrogen-doped ACF (ST-ML-AN-ST) showed ca. 80% on average, implying that a portion of nitrates was adsorbed on the prepared ACFs irreversibly.     

Ozone treatment of water-soluble polymers. IV. Ozone degradability of water-soluble polymers

The ozone degradability of water-soluble polymers, i.e., polyethylene glycol, poly(vinyl alcohol), poly(vinyl pyrrolidone), polyacrylamide, and sodium polyacrylate, was studied in the aspects of ozonization rate and degradation efficiency. The reactions of ozone with polymers were first order, respectively, with respect to ozone and polymer, except poly(vinyl alcohol) under basic condition (1/2 order with respect to ozone). The reaction rate of poly(vinyl pyrrolidone) was the largest, while those of polyacrylamide and sodium polyacrylate were almost zero. The absorption rate of ozone into the polymer solution was affected by the reaction rate, the foaming property of solution, and the self-decomposition of ozone. In terms of chain breakage and complete oxidation to CO₂, the degradation efficiency of polyethylene glycol was the best, and that of poly(vinyl pyrrolidone) was poor in spite of the high reaction rate. A little degradation was observed also in the case of polyacrylamide and sodium polyacrylate.     

Dyeing properties of novel regenerated cellulosic fibers

Two types of direct dyes (disazo and phthalocyanine) were applied to regular viscose rayon and a new regenerated cellulosic fiber (enVix), which was prepared from cellulose acetate fiber through the hydrolysis of acetyl groups, and their dyeing and fastness properties were compared. enVix exhibited better dyeability and fastness than regular viscose rayon. This was explained by the differences in the supramolecular structures of the two fibers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3481–3488, 2004     

Graft copolymerization of methyl methacrylate onto cellulosic biofibers

In this article, we have used the potassium persulfate to initiate the graft copolymerization of methyl methacrylate onto cellulosic biofibers in aqueous medium. Different reaction parameters, such as reaction time, initiator molar ratio, monomer concentration, amount of solvent, and reaction temperature, were optimized to get the maximum percentage of grafting (50.93%). The graft copolymers thus formed were characterized by Fourier transform infrared, scanning electron microscopy, X‐ray diffraction, and thermogravimetric, differential thermal analysis, and derivative thermogravimetric techniques. A mechanism is proposed to explain the generation of radicals and the initiation of graft copolymerization reactions. On grafting, percentage crystallinity decreases with reduction in its stiffness and hardness. The effect of grafting percentage on the physicochemical properties of raw as well as grafted fibers has also been investigated. The graft copolymers have been found to be more moisture resistant and also showed better chemical and thermal resistance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

UV-irradiated ozonation of water-soluble polymers

The effect of ultraviolet light on the ozonation of some water-soluble polymers such as polyethylene glycol, polyacrylamide, carboxymethyl cellulose, and poly(vinyl alcohol) was investigated. Ultraviolet light irradiation accelerated the ozonation. Acceleration was caused by the decomposition of ozone by ultraviolet light, which produced active species.     

Photo-Fenton removal of water-soluble polymers

This paper presents the results of experiments carried out in a laboratory-scale photochemical reactor on the photodegradation of different polymers in aqueous solutions by the photo-Fenton process. Solutions of three polymers, polyethyleneglicol (PEG), polyacrylamide (PAM), and polyvinylpyrrolidone (PVP), were tested under different conditions. The reaction progress was evaluated by sampling and analyzing the total organic carbon concentration in solution (TOC) along the reaction time. The behavior of the different polymers is discussed, based on the evolution of the TOC–time curves. Under specific reaction conditions, the formation and coalescence of solid particles was visually observed. Solids formation occurred simultaneously to a sharp decrease in the TOC of the liquid phase. This may be favorable for the treatment of industrial wastewater containing polymers, since the photodegradation process can be coupled with solid separation systems, which may reduce the treatment cost.