Concentration Of Quaternary Ammonium Salts Research Articles

The Role of Cation Hydrophobicity on Ion Transport Selectivity in Nanopore Membranes

Quaternary ammonium salts (QAS) are cationic surfactants widely used in domestic and industrial products like detergents, disinfectants, personal care products, and more. Due to their substantial use, QAS are accidentally or intentionally released into the environment and have been detected in surface waters, wastewaters, and soil sediments. The concentration of QAS in groundwaters has greatly increased, and this poses serious health threats. Therefore, various methods to purify wastewaters and remove the containment QAS have been proposed. Membrane-based technologies have been used extensively, and wastewater treatment facilities often use polymeric membrane-based systems for purification. Quaternary ammonium salts are known to accumulate on the polymeric membrane surfaces and within the membrane pores. This leads to membrane fouling, which is a major obstacle for efficient operation of these membrane systems. Direct evidence is presented here for the adsorption of aqueous QAS adsorbed on a polycarbonate membrane studied. Potentiometric experiments, in accordance with surface contact angle and infrared spectroscopy measurements, illustrate the extent of adsorption on the membrane surface and within the membrane nanopores. Using a homologous quaternary ammonium series, we focus on how the hydrophobicity of the adsorbing cationic surfactant directly affects membrane separation performance, specifically cation transport and membrane permselectivity. It was found that the strength of the interaction between the QAS and the polycarbonate membrane was directly proportional to QAS hydrophobicity (i.e. carbon number). Excessive adsorption to the membrane surface and pore walls deteriorated membrane separation performance and required extra rinsing using an aqueous KCl solution to remove the QAS foulant.

Определение четвертичных аммониевых солей и полигексаметиленбигуанид гидрохлорида при совместном присутствии в дезинфицирующих средствах

Titrimetric methods for determining the concentration of quaternary ammonium salts and polyhexame­thylenebiguanide hydrochloride in the presence of a disinfectant are described. In addition, as auxiliary components, the agent contains a nonionic surfactant and an alkyl polyglucoside and a disodium salt of ethylenediaminetetraacetic acid as a complexing agent. The main differences between the methods proposed by us for the determination of quaternary ammonium salts and polyhexamethylenebiguanide hydrochloride is the use of not sodium dodecyl sulfate as a titrant, but a solution of the disinfectant itself, which greatly facilitated the visual fixation of the equivalence point. In addition, the volume of the indicator (methylene blue and bromophenol blue) was selected in such a way that the exposure between the portions of the added titrant was not prolonged, because this would increase the overall duration of the analysis. When titrating with polyhexamethylenebiguanide hydrochloride, the vo­lume of the indicator is selected in such a way as to minimize the interfering effect of HR, which are also part of disinfectants. The reproducibility of the developed methods has been confirmed in accredited laboratories of the relevant state institutions of the Republic of Belarus. Metrological characteristics of the developed methods: accuracy index±3.7 %, reproducibility index 4.0 %, n = 17, P = 0.95 – to determine the QAS; accuracy index±4.2 %, reproducibility index 5.5 %, n = 17, P = 0.95 – for the determination of PHMBG.

ЭПОКСИДНЫЕ АНТИФРИКЦИОННЫЕ ПОКРЫТИЯ, НАПОЛНЕННЫЕ ОБРАБОТАННОЙ ПОВЕРХНОСТНО-АКТИВНЫМИ ВЕЩЕСТВАМИ ЗОЛОЙ РИСОВОЙ ШЕЛУХИ

The use of epoxy antifriction coatings can significantly reduce thermal stress in the friction zone and expand the coating working temperature interval while keeping high wear resistance. The paper considers the effect of non-activated and activated by surfactants silicate filler – rice husk ash on the physicochemical and mechanical properties of epoxy materials applied as antifriction coatings. All studied samples of rice husk ash, both initial and activated with surfactants, have an alkaline surface nature. The study identified that all cationic quaternary ammonium salts (QAS) reduce the pH of rice husk ash. At the same time, nonionic OXIPAV increases this indicator. Activation of the rice husk ash surface, both by the quaternary ammonium salts and aminosilanes, significantly reduces the porosity of this silicate. In this case, the average pore diameter does not change significantly, and their specific surface area decreases significantly, to a lesser extent, when activated by nonionic quaternary ammonium salts. The application of quaternary ammonium salts and aminosilanes in the amount of 33 % for activation of the surface of the investigated silicate filler reduces its modifying effect in epoxy compositions, regardless of the chemical structure of the surfactants used, which is not a typical effect. Therefore, the authors assumed that the suboptimal concentration of quaternary ammonium salts and aminosilanes was used. The study identified that the optimal concentration of 50 % alcohol solution of KATAPAV is 14.7–21 %. In this range of the QAS content, there is a significant increase in hardness (about 40 %), a slight decrease in wear (about 10 %), and a significant decrease in the coefficient of static friction (up to 2 times). At the same time, the authors observed an increase in adhesion to metal up to 3 times and bending strength up to 25 %. Thus, rice husk ash activated with an optimal amount of quaternary ammonium salts is an effective modifier of epoxy coatings, which improves their antifriction properties and increases wear resistance, hardness, strength, and adhesion characteristics.

Preparation of antimicrobial wound dressings via thiol–ene photopolymerization reaction

Preparation of poly (urethane-acrylate) based wound dressings with the ability to boost self-healing of skin tissue through physical protection and maintaining hygiene and moist environment over wounded area is described in the present work. The dressings were prepared via a visible-light induced thiol–ene photopolymerization reaction of a mixture consisting methacrylate urethane prepolymers with hydrophilic and hydrophobic backbones, a quaternary ammonium salt containing methacrylate monomer as an antimicrobial agent, hydroxyethyl methacrylate as reactive diluent and a tetra-functional thiol molecule as a transfer agent. The prepared dressings were characterized and their performance as wound dressings were evaluated through measuring their equilibrium water absorption (EWA), water vapor transmission rate (WVTR), mechanical, and biological properties. Based on recorded data, the optimized dressing formulation had suitable tensile strength even at fully hydrated state and it could preserve the appropriate moist environment by balanced EWA and WVTR ratio. MTT assay confirmed proper cytocompatibility of those dressings containing optimized concentration of quaternary ammonium salt containing monomer (20 wt% or less). Examination of antibacterial activity against different Gram positive, Gram negative bacteria and a fungal strain revealed a complete killing ability for those dressings containing at least 20 wt% of quaternary ammonium salt containing monomer.

Relationship between surface concentration of amphiphilic quaternary ammonium biocides in electrospun polymer fibers and biocidal activity

Electrospinning was utilized to generate antimicrobial Nylon and polycarbonate fibers for potential applications including self-decontaminating fabrics, wound dressings, and filtration media. The effects of quaternary ammonium salt concentration on fiber morphology, diameter, and antimicrobial activity of the resulting fiber mats were investigated. Fibers were characterized utilizing scanning electron microscopy and X-ray photoelectron spectroscopy, while antimicrobial activity was evaluated against Staphylococcus aureus. The co-electrospinning of soluble quaternary ammonium biocides within polymeric solutions generated uniform fibers with diameters ranging from 91 to 278nm for Nylon and 0.55–2.34μm for polycarbonate. Fiber morphology and diameter of the resulting fibers were shown to be dependent on polymer type and biocide concentration. A positive correlation between surface concentration of quaternary ammonium salts and antimicrobial activity was observed as fibers loaded with biocides exhibited up to a 7 log reduction of viable bacteria.

Inorganic−Organic Hybrid Coatings on Stainless Steel by Layer-by-Layer Deposition and Surface-Initiated Atom-Transfer-Radical Polymerization for Combating Biocorrosion

To improve the biocorrosion resistance of stainless steel (SS) and to confer the bactericidal function on its surface for inhibiting bacterial adhesion and biofilm formation, well-defined inorganic-organic hybrid coatings, consisting of the inner compact titanium oxide multilayers and outer dense poly(vinyl-N-hexylpyridinium) brushes, were successfully developed. Nanostructured titanium oxide multilayer coatings were first built up on the SS substrates via the layer-by-layer sol-gel deposition process. The trichlorosilane coupling agent, containing the alkyl halide atom-transfer-radical polymerization (ATRP) initiator, was subsequently immobilized on the titanium oxide coatings for surface-initiated ATRP of 4-vinylpyridine (4VP). The pyridium nitrogen moieties of the covalently immobilized 4VP polymer, or P(4VP), brushes were quaternized with hexyl bromide to produce a high concentration of quaternary ammonium salt on the SS surfaces. The excellent antibacterial efficiency of the grafted polycations, poly(vinyl-N-pyridinium bromide), was revealed by viable cell counts and atomic force microscopy images of the surface. The effectiveness of the hybrid coatings in corrosion protection was verified by the Tafel plot and electrochemical impedance spectroscopy measurements.

Poly(vinylidene fluoride)‐graft‐Poly(N‐vinyl‐2‐pyrrolidone) Copolymers Prepared via a RAFT‐Mediated Process and their Use in Antifouling and Antibacterial Membranes

PNVP-g-PVDF copolymers were synthesized and used to produce microfiltration membranes. The pore size and distribution varied with the grafting concentration and the density of graft points. A significant decrease of the amounts of adsorbed BSA indicated improved antifouling properties of PVDF. The MF membranes were further functionalized via surface-initiated block copolymerization with DMAEMA to obtain (PVDF-g-PNVP)-b-PDMAEMA MF membranes. Quaternization of the tertiary amine groups of the PDMAEMA brushes gave rise to a high concentration of quaternary ammonium salt on the membrane surfaces. The bactericidal effect of the QAS-functionalized membranes on E. coli was also demonstrated and discussed.

Non-hydrothermal synthesis of mesoporous materials using sodium silicate from coal fly ash

Siliceous mesoporous materials with pores of ordered 2-D hexagonal structure were successfully prepared without hydrothermal treatment from condensation–polymerization of various concentration of quaternary ammonium salt as structure directing agents and silica precursor from the supernatant of coal fly ash (CFA) in the presence of catalyst. The synthesized materials had high surface area of ca. 740 m 2 g −1 and pore volume of ca. 0.42 mL g −1. The synthesized material exhibited a narrow size pore distribution and the mean pore diameter as measured by Dollimore–Heal method was about 2.3 nm. The formation of ammonium salt that act as precipitant during the synthesis enable the hydrolysis and co-condensation of the sodium silicate at room temperature.

POLYMER MICROSPHERES WITH PERMANENT ANTIBACTERIAL SURFACE FROM SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION OF 4-VINYLPYRIDINE AND QUATERNIZATION

Crosslinked poly(4-vinylbenzyl chloride) (PVBC) microspheres of about 550 μm in diameter were first synthesized by suspension copolymerization of 4-vinylbenzyl chloride (VBC) in the presence of a crosslinking agent, ethylene glycol dimethacrylate (EGDMA). Subsequent surface-initiated atom transfer radical polymerization (ATRP) of 4-vinylpyridine (4VP), using the VBC units of PVBC on the microsphere surface as the macroinitiators, produced well-defined (nearly monodisperse) and covalently tethered poly(4-vinylpyridine) (P4VP) brushes. Quaternization of the tertiary amine groups of the P4VP brushes with hexyl bromide gave rise to a high concentration of quaternary ammonium salt (QAS) on the microsphere surfaces. The chemical composition of the microsphere surfaces at various stages of surface modification was characterized by X-ray photoelectron spectroscopy (XPS). The bactericidal effect of the QAS-functionalized microspheres on Escherichia coli (E. coli) was demonstrated. No significant loss in the surface bactericidal activity of the microsphere was observed during repeated applications.

Electroanalysis at ultramicroelectrodes of oils and fats: Application to the determination of Vitamin E

Differential pulse voltammetry at ultramicroelectrode (UME) has been applied to the determination of Vitamin E concentration in vegetable oils and fats mixed with solvent at 60°C. The use of UME permits a low proportion of solvent in solution. The solvent was N-methyl-pyrrolidone in which the concentration of quaternary ammonium salt used as supporting electrolyte must be less than 0.01 M in order to prevent the formation of two non-miscible phases. Only one oxidation peak was observed by differential pulse voltammetry. This peak was attributed to the oxidation of all the tocols which constitute Vitamin E and which are not separately analysed by this method. α-Tocopherol was used as added standard in the determination of the global concentration of Vitamin E. Several commercial vegetable oils and pork lards were electroanalysed. This analytical method gives a good estimation of the total amount of Vitamin E compared with chromatographic results. In pork lards, the quantities measured are in the range 5×10 −5 to 1×10 −4 M. Lards arising from pork which had received α-tocopherol supplement diet can be detected.

Influence of concentration and structure of quaternary ammonium salts on their antifouling efficiency tested against a community of marine bacteria

With the view of incorporating quaternary ammonium salts (QAs) in marine paints, nineteen of these were tested against a community of marine bacteria, at a temperature and salinity close to those of seawater. The concentration of QAs and the length of the main substituting chain are the main parameters affecting the growth and adhesion of bacteria, but the nature of (i) the other chains, (ii) the counter‐ion and (iii) the rings when inserted in the QA molecule also influenced the bacteria. Increasing the concentration of the QAs decreased the growth rate of the bacteria, the maximum cell density at the plateau and the rate of adhesion. The effect of increasing the length of the main chain depended on the range of carbon numbers. Below 7 carbon atoms, the growth rate was not significantly modified, but the numbers of cells at the plateau increased in contrast with the adhesion rate which decreased rapidly. Increasing the length of the chain to between 7 and 16 carbon atoms resulted in a decrease in the growth rate, a decrease and then a stabilisation in the numbers of cells at the plateau and no further change in the adhesion rate. Possibly an increase in growth rate, adhesion rate and in the numbers of cells at the plateau may occur above 16 carbon atoms. In contrast, the length of the other chains influenced positively the cell concentration at the plateau, and more generally the efficiency of QAs decreased substantially when these chains had the same numbers of carbon atoms. QAs with iodide as counter‐ion were more effective than those with chloride or bromide and phenyl was more effective than benzyl as rings inserted in QAs. The minimum inhibitory concentrations (MIC) were often very high if compared to standard methods with laboratory strains, and this can be tentatively explained by the dominance of Gram— bacteria in the community assayed, the development of resistant strains in the cultures used with time and the presence of organic matter in the culture medium.

Capillary zone electrophoresis of neutral organic molecules in organic – aqueous solution

AbstractVery good separations of non‐ionic organic compounds have been achieved by capillary zone electrophoresis (CZE) using a tetrahep‐tylammonium salt as an additive in aqueous acetonitrile as solvent. A systematic study was undertaken to determine the effect of experimental parameters on electroosmotic mobility and electro‐phoretic mobility. It was found that pH, acetonitrile concentration, and the type and concentration of quaternary ammonium salt are important experimental variables. Under appropriate conditions, the separation window was enlarged and a broad range of electrically neutral organics, including very hydrophobic compounds (e. g. poly‐cyclic aromatic hydrocarbons) and fairly hydrophilic compounds were separated in a relatively short time. By adjusting the separation conditions, high resolution CZE of a specific group of neutral organic compounds could be achieved. A method for calculation of capacity factor was proposed and capacity factors for a variety of non‐lonic organic compounds were calculated.

Biocidal polymers active by contact. II. Biological evaluation of polyurethane coatings with pendant quaternary ammonium salts

AbstractFilms of polyurethane were prepared by reaction of hydroxytelechelic polybutadienes carrying covalently bound quaternary ammonium salts with an aliphatic triisocyanate. These coatings exhibited high biocidal activity against Gram‐positive and Gram‐negative bacteria, yeasts, and moulds. It was found that many parameters controlled the bioactivity such as the time of contact between films and bacteria, the [NCO]/[OH] ratio used to prepare the cured polyurethane, the concentration of quaternary ammonium salts in the coating, and the length of the alkyl chain from C8 to C16 linked to the quaternary nitrogen atom. A secondary phenomenon of diffusion only observed with the shorter alkyl chains (C8 and C10) was shown to be due to synthesis residues. After these water‐soluble impurities are eliminated, the biocidal activity remains excellent: then it is due only to a contact polymer bacteria. © 1993 John Wiley & Sons, Inc.