Development of porous lamellar chitosan‐alginate membranes: Effect of different surfactants on biomaterial properties

In this work, porous lamellar chitosan‐alginate membranes were developed without the use of freeze‐drying methods or other vacuum‐based approaches. The effects of two different surfactants, Tween 80 and Pluronic F68, on the properties of the membranes were evaluated, aiming at the production of stable consistent foams with improved polysaccharide dispersion. The membranes prepared with Tween 80 had a tensile strength around 1.5 MPa, elongation at break of 2.1% and liquid uptake from 590 to 1370% in distinct solutions, increasing their thickness in up to 3.9 times when immersed in water. The membranes obtained with Pluronic F68 had a tensile strength of 1.0 MPa, elongation at break of 2.0% and liquid uptake from 774 to 1380%, showing an increase in thickness around 3.2 times after exposure to water. The antimicrobial properties of both membranes were also evaluated, showing that despite being porous, the membranes can provide some protection against bacterial permeation. Therefore, membranes produced with Tween 80 and Pluronic F68 were considered to have high potential for use in the production of wound dressings and scaffolds for tissue engineering. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

聚合表面活性剂的合成及其应用

综述了近二十年来聚合表面活性剂的合成及主要应用,详细阐述了国内外对低聚表面活性剂在合成、界面吸附和溶液聚集行为方面的研究进展.已有的研究结果表明,中低分子质量的线性聚合表面活性剂不但具有很高的界面活性,可以使原油/水的界面张力达到超低,而且兼具一定的黏度,在三次采油上将具有很大的应用前景.     

Adsorption of ethoxylated alkylphenol–formaldehyde polymeric surfactants at the aqueous solution–air interface

The adsorption behaviour of some ethoxylated alkylphenol–formaldehyde polymeric non-ionic surfactants, at the aqueous solution–air interface, was investigated by measuring the surface tension (γ) as a function of concentration (C) at four temperatures. By applying the Gibbs adsorption equation to the γ versus C data, the adsorption isotherms of these polymeric surfactants were obtained. Surface concentration (Λ) of the investigated polymeric non-ionics was found to increase with decreasing temperature and decreasing hydrophobic group (R) chain length, while varying the length of polyoxyethylene chain (%EO) appeared to have an insigificant effect. Effects of temperature, %EO and chain length R on the surface pressure (π) of the surfactant solutions were also investigated.     

Durable antibacterial finish on cotton fabric by using chitosan‐based polymeric core‐shell particles

Cotton fabric with excellent antibacterial durability was obtained when treated with chitosan‐containing core‐shell particles without any chemical binders. These amphiphilic nanosized particles with antibacterial chitosan shells covalently grafted onto polymer cores were prepared via a surfactant‐free emulsion copolymerization in aqueous chitosan. Herein, two core‐shell particles, one with poly(n‐butyl acrylate) soft core and another with crosslinked poly(N‐isopropylamide) hard core, were synthesized and applied to cotton fabric by a conventional pad‐dry‐cure process. Antimicrobial activity was evaluated quantitatively using a Shake Flask Method in which the reduction of the number of Staphylococcus aureus cells was counted. The results showed that treated fabric had an excellent antibacterial property with bacterial reduction higher than 99%. The antibacterial activity maintained at over 90% reduction level even after 50 times of home laundering. The fabric surface morphology as well as the effect of latex particles with different core flexibilities on fabric hand, air permeability, break tensile strength, and elongation was investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1787–1793, 2006     

Adsorption of dyes and humic acid from water using chitosan‐encapsulated activated carbon

The adsorption isotherms and rates of two dyes and humic acid from aqueous solutions onto chitosan‐encapsulated activated carbon (CEAC) beads were measured at 30 °C. Such beads were prepared by mixing different weight percents of cuttlefish‐based chitosan (100%, 80%, 67%, and 55%) and rice‐based activated carbons. It was shown that the isotherms of dyes and humic acid were well fitted by the Freundlich equation. The adsorption capacity and rate could be enhanced when activated carbon was encapsulated with chitosan. Four simplified kinetic models including the pseudo‐first‐order equation, pseudo‐second‐order equation, intraparticle diffusion model, and the Elovich equation were tested to follow the adsorption processes. The adsorption of dyes was best described by the Elovich equation, but that of humic acid was best described by the intraparticle diffusion model. The kinetic parameters of each best‐fit model were calculated and are discussed in this paper. © 2002 Society of Chemical Industry     

Water‐based non‐ionic polymeric surfactants as oil spill dispersants

In this paper, polyisobutylene succinic anhydride adduct (PIB‐SA) was modified by esterification with polyethylene glycol (PEG 600, 1000 and 2000) to obtain mono‐ and diterminal polyoxyalkynated PIB‐SA. The monoterminal products were reacted with pentamethylene‐hexamine (PMHA). The structures were confirmed by FT–IR and ¹H NMR analysis. The surface properties, interfacial tension and the effectiveness in oil dispersion of the synthesized polymeric surfactants are reported. The maximum efficiency of oil spill dispersants was reached when the surfactant molecule had two moities (polyoxyalkylene and polyamine units). © 1999 Society of Chemical Industry     

Effectiveness test of alginate‐derived polymeric surfactants

A series of alginate‐derived polymeric surfactants (APSs) with a linear alkyl group (C8, C12, C16) was synthesized by oxidation followed by reductive amination of 2,3‐dialdehydic alginate. The products were characterized by measuring IR spectra, NMR spectra, surface tension and critical micelle concentration (cmc). They were also tested for the solubilization of azobenzene and adsorption of heavy metal. In the case of 40% CHO‐C8 APSs, the lowest interfacial tension value (31.5 m Nm^?1) was obtained at the cmc value of 1.35 g dm^?3. The dissolving capacity of 40% CHO‐C8 APS towards azobenzene was 27 times greater than that of alginate. The overall cobalt (Co²⁺) removal efficiency by adsorption using APSs was high compared with that of sodium alginate at pH 3, 5 and 7. Equilibrium aspects of cobalt adsorption onto 10% CHO‐APSs were studied, and the results show that APSs had high equilibrium capacities for cobalt uptake, 115.5 mgg^?1. © 2002 Society of Chemical Industry     

Polymeric surfactants for enhanced oil recovery. IV—Thermodynamic properties of ethoxylated alkylphenol formaldehyde polymeric surfactants

The thermodynamic properties of some low molecular weight ethoxylated alkylphenol formaldehyde polymeric surfactants have been investigated. Surface tension as a function of concentration of the surfactants in aqueous solutions was measured at 28, 38, 48 and 58°C, using the spinning drop technique. From these measurements, the minimum area per molecule at the aqueous solution/air interface (A_min) was determined. The thermodynamic parameters of micellization (ΔG_mic, ΔH_mic, ΔS_mic) and of adsorption (ΔG_ad, ΔH_ad, ΔS_ad) for these polymeric nonionics were calculated. Micellization is more sensitive to ethylene oxide chain length while adsorption is more dependent on the length of the alkyl chain.     

磺化腐植酸处理模拟电镀废水中的六价铬

以0.1 g磺化腐植酸为吸附剂,在30℃恒温振荡下对水中Cr(VI)进行吸附,用可见分光光度法测定吸附前后水中Cr(VI)的含量.结果表明,Freundlich模型能够很好地用于描述磺化腐植酸对Cr(VI)的吸附,且当溶液pH在1.8左右,吸附时间为150 min时,磺化腐植酸对Cr(VI)的吸附率可达99%以上.     

Adsorption mechanism of surfactants on nonwoven fabrics

For improved surface properties, nonwoven fabrics of polypropylene and poly(ethylene terephthalate) were treated with several kinds of surfactants, including anionic, cationic, and nonionic types. The adsorption isotherms of the anionic, cationic, and nonionic surfactants on the nonwoven fabrics were different. The adsorption isotherm of the cationic surfactant (dodecyl dimethylbenzyl/ammonium chloride) exhibited a maximum. The adsorption isotherm of the anionic surfactant (sodium dodecylbenzene sulfonate) was in the shape of the fifth Brunauer adsorption isotherm, and that of the nonionic surfactant (alkylphenol/ethylene oxide condensate) was similar to the fourth Brunauer adsorption isotherm. The time of the adsorption equilibrium was constant for the same types of adsorbate and adsorbent, and it was not related to the initial concentration. The specific surface resistance of the nonwoven fabrics decreased substantially after the adsorption of ionic surfactants. The nonwoven fabrics with the surfactants were characterized with scanning electron microscopy and X‐ray photoelectron spectroscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3210–3215, 2003     

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.     

Evaluation of the potential of polymeric carriers based on chitosan‐grafted‐polyacrylonitrile in the formulation of drug delivery systems

Graft copolymerization of chitosan with acrylonitrile (AN) was carried out by free radical polymerization using KMnO₄ and oxalic acid as a combined redox initiator system. Graft copolymerization was confirmed by Fourier transform infrared spectra (FTIR), proton nuclear magnetic resonance spectra (¹H‐NMR), thermal gravimetric analysis (TGA) measurements, and wide angle X‐ray diffraction (WAXD). In addition, further modification of the cyano groups of the grafted copolymers was performed by partial hydrolysis into carboxylic function groups with various extents. The extent of hydrolysis was monitored using FTIR spectroscopy. The potential of the hydrolyzed and unhydrolyzed grafted copolymers as polymeric carriers for drug delivery systems was extensively studied by preparation of tablets incorporated with methyl orange (MO) as a drug model. In vitro drug release was carried out in simulated gastric and intestinal conditions. The effects of grafting percentage (GP) and the extent of hydrolysis on the release kinetics were evaluated. Release continued up to 24 h for both hydrolyzed and unhydrolysed chitosan‐g‐PAN copolymers. The nature of drug transport through the polymer matrices was studied by comparing with power law or Kormeyer‐Peppas equation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of chitosan‐based dispersions

Complexation of chitosan in aqueous solutions by low molecular weight electrolytes is one of the simplest methods for the preparation of aqueous chitosan dispersions. In this work, the influence of storage time, sulfate concentration, method of preparation and surfactant content on some properties of the resultant chitosan dispersions (turbidity, viscosity and zeta potential) was analyzed. Turbidimetry was adequate to monitor the formation of particles, while viscometry was suitable to monitor changes in the dispersing phase. An analysis of the properties of these systems, mainly in terms of particle–particle and macromolecule–macromolecule interactions was carried out. Copyright © 2004 Society of Chemical Industry     

Adsorption of lanthanum by magnetic alginate‐chitosan gel beads

BACKGROUND: The risk of environmental pollution is aggravated by the increasing application of considerable amounts of rare earth elements in advanced materials. This paper reports the preparation of novel magnetic alginate–chitosan gel beads and their application for adsorption of lanthanum ions from aqueous solution. RESULTS: Stable magnetic alginate–chitosan gel beads with average diameter 0.85 ± 0.05 mm were prepared by loading iron oxide nanoparticles onto a combined alginate and chitosan absorbent. The performance of the prepared beads for the adsorption of lanthanum ions from aqueous solution was tested. It was found that various parameters, such as aqueous pH, contact time, metal ion concentration, ion strength and temperature, have an effect on the adsorption. Adsorption equilibrium was reached in 10 h and the maximum uptake capacity was 97.1 mg g^?1. From the analysis of pH, FTIR and XPS data, it is proposed that lanthanum adsorption proceeds through mechanisms of cation exchange, electrostatic interaction and surface complexation, with the oxygen atoms the main binding sites. In addition, lanthanum ions could be selectively separated from coexisting base metal ions such as Pb (II), Cd (II), Co (II), Ni (II) and Cu (II) in the aqueous solution. CONCLUSION: The prepared magnetic alginate–chitosan gel beads exhibit high uptake capacity and selectivity for lanthanum sorption, and thus can be used for adsorptive recovery of lanthanum from aqueous solutions. Copyright © 2010 Society of Chemical Industry     

Adsorption of hexavalent chromium on cationic starches with different degree of crosslinking

The influence of the degree of crosslinking in the association with the degree of cationization on the adsorption of Cr(VI) by crosslinked cationic starches (CCS) was examined. The amount of adsorbed Cr(VI) depends on the preparation of CCS before adsorption experiments (dry or preswollen CCS) and has a higher value when dry CCS are used. The amount of crosslinks in CCS needed to reach the maximum effectiveness of the cationic groups of CCS in the binding of Cr(VI) depends also on the form in which CCS are used. The adsorption capacity for Cr(VI) decreases both with dry and preswollen CCS when the adsorption temperature increases. The thermodynamic parameters are calculated. The negative values of ΔG° and ΔH° indicated that the adsorption process in both cases was spontaneous and exothermic. If preswollen CCS is used, the entropy change has a positive value and indicates that the randomness of the system increases, whereas the negative value of entropy change when Cr(VI) species are adsorbed by dry CCS shows that in this case the order of the system increases like in the classical adsorption process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

锌铝复合氧化物吸附去除水中阴离子表面活性剂

用液相共沉淀法制备锌铝类水滑石颗粒.在500℃下焙烧类水滑石转化为锌铝复合氧化物,并用XRD、TG/DTA和FT-IR等对类水滑石和锌铝复合氧化物进行表征分析.用锌铝复合氧化物吸附水中的阴离子表面活性剂,对实验条件和主要影响因素进行研究,并对其吸附机理进行了探讨,实验结果表明,锌铝复合氧化物对阴离子表面活性剂去除效果明显.     

Towards a new strategy of a chitosan‐based molecularly imprinted membrane for removal of 4‐nitrophenol in real water samples

The issue of water contaminants, which affects human and environmental health, is not trivial. It is thus paramount to find new cheap and user friendly ways to detect and remove them from the environment. Here, the synthesis of a green chitosan (CS ) based molecularly imprinted membrane for the detection and quantification of 4‐nitrophenol (4‐NO₂Ph ) in aqueous media is proposed. The concentration of 4‐NO₂Ph in a water solution was measured by HPLC analysis. CS as a functional polymer, 4‐NO₂Ph as template, 4‐[(4‐hydroxy)phenylazo]benzenesulfonic acid as ligand, and glutaraldehyde as crosslinker in the presence of polyethylene glycol as porogen were used. The membrane was characterized by SEM and Fourier transform IR analyses, which confirmed the CS and polyethylene glycol backbone of the membrane. Kinetic studies of the detection system were performed by using pseudo‐first‐order and pseudo‐second‐order models. Then, the binding efficiency between 195.33 µmol L^?1 and 9235.55 µmol L^?1 of 4‐NO₂Ph was evaluated, finding a maximum adsorption of 723.25 µmol 4‐NO₂Ph per gram of membrane consistent with the Q _max calculated from the Langmuir isotherm. The selectivity of the membrane versus three phenolic competitor molecules, sharing very similar molecular structure to 4‐NO₂Ph , was demonstrated. Finally, the applicability of the membrane to real‐world samples was evaluated, by using drinking water spiked with 7.19 µmol L^?1 of 4‐NO₂Ph , obtaining a removal efficiency of 70.6%. © 2017 Society of Chemical Industry     

Cadmium adsorption on modified chitosan‐coated bentonite: batch experimental studies

BACKGROUND: Several researchers have investigated the use of chitosan as an adsorbent for removal of heavy metals from aqueous streams. Chitosan flake or powder swells and crumbles making it unsuitable for use in an adsorption column. Chitosan also has a tendency to agglomerate or form a gel in aqueous media. The adsorption capacity can be enhanced by spreading chitosan on physical supports that can increase the accessibility of the metal binding sites. Although several attempts have been made to enhance the adsorption capacity of chitosan, using various chemicals, the sorption capacity for metal ions decreased after cross‐linking of chitosan. RESULTS: Bentonite was coated with chitosan (Chi) and its derivative, 3,4‐dimethoxy‐benzaldehyde (Chi/DMB). The product was then used as adsorbent for the removal of Cd²⁺ from aqueous solutions. The presence of imine groups resulting from chemical modification was confirmed using IR, DRS and SEM. The adsorption followed the Langmuir isotherm and could be described by pseudo‐second order kinetics. CONCLUSION: Chi/DMB coated on bentonite increased the accessibility of metal binding sites. The Chi/DMB/bentonite showed no significant pH dependence in the pH range 2–9, but bentonite coated with chitosan revealed very intensive pH dependence, which had a considerable effect on cadmium removal. As expected adsorption of Cd²⁺ by Chi/bentonite and Chi/DMB/bentonite is dependent on contact time and adsorbent dose. In addition, an EDTA solution is suitable for desorption of cadmium ions, and the reusability of Chi/DMB/bentonite is quite good. © 2012 Society of Chemical Industry     

Efficacy of La3+ entrapped chitosan bio‐polymeric matrix for the recovery of oil from oil‐in‐water emulsion

On the basis of the present study, the details of the recovery of cutting oil from oil‐in‐water emulsion using the modified forms of biopolymer chitosan viz., chitosan beads (CB), carboxylated chitosan beads (CCB), and lanthanum incorporated carboxylated chitosan beads (La‐CCB). Various oil sorption experiments were conducted using an extractive gravimetric method by optimizing various parameters such as contact time, pH, sorbent dosage, and initial oil concentration for maximum sorption. It was found that the oil removal percentage was comparatively less in the case of CB and CCB when compared with La‐CCB, which showed 85% of oil removal at acidic condition. The obtained adsorption equilibrium data was explained with Freundlich, Langmuir, D–R, and Tempkin isotherms to find the best fit for the sorption process. Thermodynamic parameters such as ΔG⁰, ΔH⁰, and ΔS⁰ were calculated in order to understand the nature of sorption process. The surface morphology and sorption of oil on the beads were confirmed by FTIR, SEM with EDAX, XRD, TGA, and DSC analysis. This work provides a potential platform for the expansion of oil removal technology. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43218.     

Synthesis and adsorption properties for metal ions of mesocyclic diamine‐grafted chitosan‐crown ether

A new type of grafted chitosan‐crown ether was synthesized using mesocyclic diamine crown ether as the grafting agent. The C2 amino group in chitosan was protected from the reaction between benzaldehyde and chitosan to form N‐benzylidene chitosan (CTB). After reaction with mesocyclic diamine crown ether of the epoxy propane group to give mesocyclic diamine‐N‐benzalidene chitosan (CTBA), the Schiff base was removed in a dilute ethanol hydrochloride solution to obtain chitosan‐crown ether (CTDA). Its structure was confirmed by FTIR spectra analysis and X‐ray diffraction analysis. Its static adsorption properties for Pb(II), Cu(II), Cd(II), and Cr(III) were studied. The experimental results showed that the grafted chitosan‐crown ether has high selectivity for the adsorption of Cu(II) in the presence of Pb(II), Cu(II), and Cd(II) and its adsorption selectivity is better than that of chitosan. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1255–1260, 2000