Influence of ionic and nonionic surfactants on analytical parameters of ion-selective electrodes based on chelating active substances

The effects of the cationic (tetrabutylammonium chloride, TBC), anionic (sodium dodecyl sulfate, SDS) and nonionic (TRITON X-100) surfactants on the potentiometric properties of zinc- and cadmium-selective electrodes (ISEs) were investigated. The studies were carried out with plasticized PVC membranes doped with several new acidic chelating ionophores. The electrode basic analytical parameters, such as measurement range, slope characteristics, detection limit, response time and selectivity coefficients in relation to some inorganic cations in the presence and absence of surfactants, were investigated. As follows from the studies, the presence of surfactants in the sample is responsible first of all for the increase in response time and in detection limit, and a decrease in the characteristic slope as well as reduction of electrode selectivity.     

Synthesis, Autoorganization and Reactivity of Amphiphilic Derivatives of 1-Aminoisoindole in Water and Formamide

In this work, we present the synthesis of cationic surfactants based on 1-aminoisoindole. The physico-chemical properties were studied by conductometry, tensiometry, dynamic light scattering and transmission electron microscopy in water and in formamide. The reactivity of these novel surfactants has been studied at concentrations below and above critical aggregation concentrations (CAC) and it was found that reactions can proceed in structured media without the addition of other catalysts.     

Synthesis and Properties of Dissymmetric Gemini Surfactants

A series of novel dissymmetric gemini cationics surfactants was synthesized by three-step reactions. The dissymmetric gemini surfactants contain a dodecanoic acid dimethylethylamine ester as the constant cationic part on one side of the hydroxypropyl center and a similar other cationic part, but with a different acid length (from octanoic to palmitic), on the other side. The critical micelle concentration (CMC) and the effectiveness of surface tension reduction (γ _CMC) were determined. The surface tension measurements of dissymmetric gemini surfactants showed good water solubility, and low CMC had great efficiency in lowering the surface tension and a strong adsorption at the air/water interface. The CMC was observed to increase initially with the increase of the ester bond alkyl group. They also showed good foaming properties and wetting capabilites.     

Flexible Semicrown Ether-Linked Symmetric Cationic Gemini Surfactants: Synthesis and Evaluation as Catalysts for Acceleration of Diastereoselective [3 + 2] Cycloaddition Reaction in Reversed Phase Micellar Media

Novel cationic gemini surfactants with a hydrophilic oligo-oxyethylene spacer group were synthesized and their physicochemical properties were identified. Computational studies for these compounds were also performed; molecular geometry, frontier molecular orbitals, and quantum chemical parameters were calculated using density functional theory (DFT). After exploration for catalytic activity, it was found that these surfactants can efficaciously accelerate the [3 + 2] cycloaddition reactions in reversed phase micellar media.     

Polymer‐Cationic Surfactant Interaction: 1. Surface and Physicochemical Properties of Polyvinyl Alcohol (PVA)‐S‐Alkyl Isothiouronium Bromide Surfactant Mixed Systems

Surface properties of polyvinyl alcohol (nonionic polymer) and three synthesized cationic surfactants, namely, S‐alkyl isothiouronium bromide at different mole fractions of 1:9, 3:7, 5:5, 7:3, and 9:1, were investigated. The values of the surface parameters were discussed according to the type of interaction between the cationic surfactant and type of polymer studied. The S‐alkyl isothiouronium bromide surfactant molecules are positively charged molecules, and the PVA chains contain hydroxyl groups that are partially negatively charged centers. The comparison between the surface properties of the individual cationic surfactants and their mixture with PVA polymer showed that the mixed systems have some advantages over the individual cationic surfactants.     

Effects of surfactants on the microstructures of electrospun polyacrylonitrile nanofibers and their carbonized analogs

In this study, the influence of surfactants on the processability of electrospun polyacrylonitrile (PAN) nanofibers and their carbonized analogs was investigated. The surfactants employed in this effort are Triton X‐100 (nonionic surfactant, SF‐N), sodium dodecyl sulfate (SDS) (anionic surfactant, SF‐A), and hexadecyltrimethylammonium bromide (HDTMAB) (cationic surfactant, SF‐C). Interactions between electrospun PAN and the surfactants, reflected in effects on as‐spun and carbonized nanofiber morphologies and microstructures, were explored. The results show that uniform nanofibers are obtained when cationic and anionic surfactants (surfactant free and nonionic surfactants) are utilized in the preparation of electrospun PAN. In contrast, a bead‐on‐a‐string morphology results when the aniconic and cationic surfactants are present, and defect structure is enhanced with cationic surfactant addition. Moreover, fiber breakage is observed when the nonionic surfactant Triton X‐100 is employed for electrospinning. After carbonizaition, the PAN polymers were observed to have less ordered structures with addition of any type of surfactant used for electrospinning and the disorder becomes more pronounced when the anionic surfactant is utilized. Owing to the fact that microstructure defects create midband gap states that enable more electrons to be emitted from the fiber, an enhancement of electron emission is observed for PAN electrospun in the presence of the anionic surfactant. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3726–3735, 2013     

Thermal condensation of fatty acids and amines with proteins

Useful, potentially low cost, polypeptide surfactants were prepared directly from the thermal condensation (ca. 240 C, ca. 1 hr) of proteins (wool, vegetable protein, gelatin, and chicken feather) with long chain fatty acids (undecylenic, lauric, and stearic) or fatty amines (dodecylamine and N-[γ-aminopropyl] dodecylamine). Dilute aqueous solutions of these surfactants, at appropriate pHs, exhibit good foaming characteristics and low surface tensions. The condensation reaction is envisioned as a transamidification in which terminal anionic groups (carboxylic acid from fatty acids) or cationic groups (primary amino from fatty amines) are produced according to the following reactions     

阳离子表面活性剂对4A沸石晶化过程的影响

研究了阳离子表面活性剂加入量对4A沸石晶化速度以及阳离子表面活性剂的碳氢链长对4A沸石晶化速度和粒度的影响。结果表明,添加少量的阳离子表面活性剂,即阳离子表面活性剂与氧化铝的摩尔比不大于0 1,4A沸石晶化速度随阳离子表面活性剂的加入量及碳氢链长的增加而增加,可使4A沸石晶化时间缩短20%,并使4A沸石的平均粒度减小,粒度分布变窄。     

Corrosion Inhibition by Some Cationic Surfactants in Oil Fields

Two cationic surfactants, namely, tetradecyl dimethyl benzyl ammonium chloride (TDBAC) and tributyl tetradecyl phosphonium chloride (TTPC) were supplied from the local market and characterized. The adsorption tendency of the two surfactants was estimated from the values of the depression of surface tension of the water at the critical micelle concentration. The studied surfactants were evaluated as antimicrobial agents against sulfate-reducing bacteria. These cationic surfactants showed good antimicrobial activities against the tested microorganisms. It was also found that these compounds are good corrosion inhibitors for carbon steel in 0.5?M HCl at doses of 25?C600?ppm.     

Aqueous Ozonation Of Surfactants: A Review

The aqueous ozonation reactions of surfactants have been reviewed, including the degree of reaction and ozonation byproduct identity. Compounds are classified into three groups: anionic, cationic and non-ionic surfactants. Experimental conditions for each study reviewed are summarized. Much work has been carried out under conditions unlikely to occur during drinking water treatment. Thus, most of the findings of the papers reviewed cannot be directly applied to potable water treatment. However this review can serve to indicate the likely reactivity of the individual surfactants towards ozone and the possible byproducts formed. This reactivity depends mainly upon the chemical structure of the surfactants. The removal of surfactants is pH dependent, with the best results being obtained in alkaline media. High ozone doses usually do not cause complete disruption of the surfactants, while smaller doses are sufficient to enhance their biodegradation.     

Ecological behavior of cationic surfactants from fabric softeners in the aquatic environment

The use of cationic surfactants in fabric softeners has reached considerable proportions in the Western industrialized nations during the last 10 years. In the Federal Republic of Germany alone, some 22,000 ton of cationic surfactants were marketed in 1981 for this specific purpose. The considerable share (12%) of total consumption which this class of surfactants accounts for is equivalent to a theoretical wastewater concentration of ca. 5 mg/L. Consequently, it raises questions concerning environmental behavior of this class of substances. The following factors are of substantial importance in this regard: acute and chronic toxicity in the aquatic environment; biodegradability under aerobic and anaerobic conditions; and the possibility of bioaccumulation in the aquatic organisms, particularly in fish. Basically, the ecological behavior of cationic surfactants, like that of distearyl dimethyl ammonium chloride (DSDMAC) and dialkyl imidazolinium salts (DAIC) which are mostly used, is determined markedly by their physicochemical properties, above all their strong adsorption on surfaces, e.g., on clay minerals or on activated sludge, thus leading to their elimination in water treatment plants and water courses. Of far-reaching consequence from the toxicological aspect is the fact that they form neutral salts with the anionic surfactants present in excess in domestic wastewater, thus leading to a considerable decrease in toxicity. Although adsorption and ion-exchange processes are primarily effective in climination of cationic surfactants of the DSDMAC and DAIC types in wastewater treatment, there are significant indications on the basis of experiments that these substances are subject to extensive aerobic biochemical degradation. However, it appears that anaerobic degradation does not take place. Tests conducted so far on the bioaccumulation behavior, particularly on a laboratory scale, indicate that these substances practically do not accumulate in the edible parts of fish and thus no risks are being discerned at present as regards the residue situation.     

Cholic Acid-Derived Facial Surfactants with Long Side-Chain Quaternary Ammonium: Synthesis and Antimicrobial Activity Study

Four cholic acid cationic surfactants containing a flexible long aliphatic chain were synthesized efficiently. A long aliphatic chain was introduced first on the side-chain carboxyl of cholic acid by one-pot condensation reaction of cholic acid and C12–C18 amines using DCC (Dicyclohexylcarbodiimide) and HOBt (N-hydroxybenzotrizole) as condensation agents for the formation of an amide framework. Then reduction of the amide and quaternization gave a cationic group for strengthening hydrophilicity. This strategy offered a very straightforward and efficient method for access to the designed surfactants in good overall yields. Preliminary results show that an increase both in the length of the hydrophobic tail and in the number of charged groups lowered the CMC of cholic acid-derived cationic surfactants. Cholic acid-based cationic surfactants containing a flexible longer aliphatic chain and a quaternary ammonium had the highest antimicrobial activity.     

Clay Swelling Inhibition Using Novel Cationic Gemini Surfactants with Different Spacers

Hydration of shale formation by water-based drilling fluids leads to several problems, such as the collapse of boreholes, tight holes, and stuck pipe, which may impede further drilling and time loss in rectifying the problems, leading to heavy economic losses. This study reports the development of new gemini cationic surfactants as shale-swelling inhibitors. These gemini surfactants are structurally similar but differ in terms of the spacer group. Saturated butyl group ( GS1 ) and unsaturated 2-butenyl ( GS2 ) and 2-butynyl ( GS3 ) were introduced as spacer groups of gemini surfactants. To assess the performance of new gemini cationic surfactants, two reliable clay sources were considered. The first clay is from an unconventional formation and the second clay is sodium bentonite. The inhibition characteristics of gemini surfactants were evaluated using dynamic swelling, hot rolling, rheology, and filtration experiments. Different formulations based on commercially available solutions for shale-swelling inhibitors were applied and compared with cationic shale inhibitors. It was observed that the new gemini cationic surfactants with different spacers (saturated and unsaturated) reduced the shale swelling by different percentages. The GS2 surfactant, containing an unsaturated double bond proved to be a good swelling inhibitor as compared to GS1 and GS3 . It also showed acceptable performance compared with the common shale inhibitor (KCl) used in the industry. The addition of surfactant has less impact on the rheological properties as compared to KCl. The filtration properties of the base mud were unchanged when surfactants were used. However, the commercial inhibitor, KCl, significantly increased the filtration volume that is associated with the disintegration of the clay. In summary, unlike commercial inhibitors, the synthesized surfactants reduced the clay swelling without affecting the other properties of the drilling fluids.     

Selective froth flotation of PVC from PVC/PET mixtures for the plastics recycling industry

It was found that strongly alkaline solutions of sodium hydroxide are able to destroy the hydrophobicity of polyethylene terephthalate (PET) whereas the hydrophobicity of polyvinyl chloride (PVC) remains only slightly affected by these solutions. On this basis, a technology involving treatment of PET and PVC particles with alkaline solutions followed by froth flotation of PVC with nonionic surfactants has been developed and tested at a laboratory scale. In both steps of this technology, appropriate experimental conditions, such as concentration of reagents, temperature and residence time, have been optimized through a detailed examination of all these variables on the efficiency and selectivity of PVC separation from PVC/PET mixtures of varying composition. It is demonstrated that using this technology 95–100% recovery of PET and PVC can be achieved in separate products from a variety of PVC/PET mixtures.     

Use of Surfactants to Enhance the Removal of PAHs from Soil

The efficiency of soil remediation is often limited by the low aqueous solubility of Polycyclic Aromatic Hydrocarbons, PAHs. Surfactants can then be used to enhance the removal of PAHs from soils. The dissolution of pure solid deposit of benzo(a)pyrene, B(a)P, has shown that cationic surfactants are the most efficient to increase the aqueous solubility of B(a)P, when compared to neutral or anionic surfactants. In this paper we compare by using soil suspension washings, the efficiency of two surfactants (i) a cationic surfactant, the benzyldimethyl dodecylammonium bromide, BDDA, and (ii) a neutral one, the t-octylphenoxypolyethoxy ethanol, triton X-100. The losses of surfactant, by adsorption on soil or precipitation, were measured together with the release of B(a)P, chosen as a model molecule, representative of all the PAHs. The efficiency of surfactants used in blend was then compared to the efficiency of surfactants alone.     

Chemical modification of PVC by different nucleophiles in solvent/non-solvent system at high temperature

Chemical modification of polyvinyl chloride by nucleophiles is a versatile method for preparation of new functional polymers. Modification of PVC was carried out using different nucleophiles (Nu) in ethylene glycol (EG)/N,N-dimethylformamide (DMF) (1:1 by volume) solution. OH^?, N₃^?, and SCN^? were examined as nucleophiles in this study. The FTIR spectrum confirmed substitution of Cl by nucleophiles and also the elimination of HCl in the modification reaction of PVC. The glass transition temperatures (T_gs) of modified-PVC samples were in the order N₃^? > SCN^? > OH^? and were equal to 87.6, 86.8 and 78.15 °C, respectively. The T_5% (the temperature at which weight loss is 5%) of PVC was 266 °C, while after 1 h modification by OH^? it reduced to 197 °C. After alkaline modification, the scanning electron microscopy (SEM) images not only showed an increase in surface roughness and porosity, but also revealed a relatively large drop in average particle size from 160 to 80 µm. Molecular weight and molecular weight distribution were determined by gel permeation chromatography (GPC). The GPC results showed that the number average molecular weight (M_n) and weight average molecular weight (M_w) were decreased from 79,950 and 176,360 g mol^?1 in crude PVC to 45,370 and 99,930 g mol^?1, respectively, after 1 h modification by OH^?. Alkaline treatment also decreased the mechanical strength of PVC.     

Quaternarized cationic poly[(vinyl chloride)-co-(vinyl chloroacetate)] binary copolymer as non-migration antibacterial additive in PVC matrix

Antibacterial polyvinyl chloride (PVC) materials have drawn considerable attention since their wide application in medical devices. The objective of this study is to develop a novel quaternary ammonium cationic vinyl chloride copolymer, which can be potentially used as antibacterial additive in PVC matrix. Initially, the low average-number molecular weight poly[(vinyl chloride)-co-(vinyl chloroacetate)] (PVC-co-PVCA) is synthesized by precipitation copolymerization. Subsequently, quaternary ammonium cationic moieties with different lengths of alkyl chains are introduced into the copolymers via quaternization reaction between alkyl-dimethyl tertiary amines with acyl chloride groups. The successful synthesis of PVC-co-PVCA and quaternarized copolymers are carefully confirmed by Fourier transform infrared spectroscopy, nuclear magnetic resonance (1H NMR), and x-ray photoelectron spectroscopy. The antibacterial behaviors of the quaternarized copolymers and its blends with PVC are investigated. The results reveal that all the PVC blends containing at least 5% by weight of quaternarized copolymer have superior bacteriostasis ratio (>99.6%) against both Escherichia coli (E.coli) and Staphylococcus aureus (S. aureus) due to the incorporation of quaternary ammonium groups. Meanwhile, the cationic copolymer exhibits excellent antifouling and much lower migration rate (<0.4%). These interesting consequences endow the quaternarized copolymers as alternative antibacterial agents possess a great deal of potential for use in PVC materials.     

Solubility of Two Disperse Dyes Derived from <Emphasis Type="Italic">N</Emphasis>-Alkyl and <Emphasis Type="Italic">N</Emphasis>-Carboxylic Acid Naphthalimides in the Presence of Gemini Cationic Surfactants

The solubility of naphthalimide-based monoazo dyes containing N-ethyl and N-ethanoic acid groups was investigated in the presence of a conventional monomeric counterpart (DTAB) and two cationic gemini surfactants (12-4-12 or 14-4-14) individually. The effective parameters on dye solubility such as temperature, time and concentration of surfactants were investigated by UV–Visible spectrophotometry. The results demonstrate that the solubility of both dyes was considerably increased at concentrations above the surfactant CMC. The wavelength for the maximum absorbance of dyes in the aqueous solution shifts toward longer wavelengths with changes in the concentration of the cationic surfactants. A kinetic study of solubilization of dyes in cationic surfactants solution showed that the rate of solubilization follows the pseudo-first-order reactions. Rates of solubilization were in the range of 0.5 × 10⁻³ to 6.8 × 10⁻³ min⁻¹ for both dyes. The disperse dye containing a carboxylic acid group (dye 2) has a higher solubility rate than the dye containing an alkyl group (dye 1). The type of surfactant has a very low effect on adsorption of dye 1 onto the polyester fibers, whereas changing the surfactant type from DTAB to 12-4-12 or 14-4-14 causes adsorption of dye 2 on polyester to decrease.     

Mixtures of anionic and cationic surfactants with single and twin head groups: Solubilization and adsolubilization of styrene and ethylcyclohexane

Mixtures of anionic and cationic surfactants with single and twin head groups were used to solubilized styrene and ethylcyclohexane into mixed micelles and adsolubilize them into mixed admicelles on silica and alumina surfaces. Two combinations of anionic and cationic surfactants were studied: (i) a single-head anionic surfactant, sodium dodecyl sulfate (SDS), with a twin-head cationic surfactant, pentamethyl-octadecyl-1,3-propane diammonium dichloride (PODD), and (ii) a twin-head anionic surfactant, sodium hexadecyl-diphenyloxide disulfonate (SHDPDS), with a single-head cationic surfactant, dodecylpyridinium chloride (DPCl). Mixtures of SDS/PODD showed solubilization synergism (increased oil solubilization capacity) when mixed at a molar ratio of 1∶3; however, the SHD-PDS/DPCl mixture at a ratio of 3∶1 did not show solubilization enhancement over SHDPDS alone. Adsolubilization studies of SDS/PODD (enriched in PODD) adsorbed on negatively charged silica and SHDPDS/DPCl adsorbed on positively charged alumina showed that while mixtures of anionic and cationic surfactants had little effect on the adsolubilization of styrene, the adsolubilization of ethylcyclohexane was greater in mixed SHPDS/DPCl systems than for SHDPDS alone. Finally, it was concluded that whereas mixing anionic and cationic surfactants with single and double head groups can improve the solubilization capacity of micelles or admicelles, the magnitude of the solubilization enhancement depends on the molecular structure of the surfactant and the ratio of anionic surfactant to cationic surfactant in the micelle or admicelle.     

Some new developments in surfactant analysis

Three new analytical methods for surfactants have been developed and evaluated, and the stoichiometry in cationic titration of a dianionic surfactant has been determined. The three methods include: (a) a rapid method for pyrolytic cleavage of hydrophobic groups from surfactants to hydrocarbons, which can be used for quantitative identification of the hydrophobic groups; (b) a molecular weight method for alkylphenoxy and alkoxy polyethoxylates based on sulfation followed by cationic titration; and (c) a microcationic titration method designed for low levels (1–10 microequivalents) of anionic surfactants, which possesses certain advantages over conventional methods. Previously stoichiometry in cationic titration has been reported only for monoanionic surfactants. In a study of a dianionic surfactant,n-octadecylbutane 1,4-disulfate, each sulfate group was found to react in a 1:1 equivalent ratio with a cationic titrant.