Cetylpyridinium Chloride Concentration Research Articles

Hexavalent chromium ion removal through micellar enhanced ultrafiltration

Abstract Micellar enhanced ultrafiltration (MEUF) experiments were carried out in an unstirred batch cell using cetyl pyridinium chloride (CPC) as the surfactant to analyze the adsorption of chromate ions on the surfaces of the surfactant micelles. The influence of independent variables was studied on the retention of the surfactant and chromate ions as well as on permeating flux. The flux, for a particular pressure, remained constant against constant bulk concentration of CPC, suggesting negligible concentration polarization in the range of feed surfactant concentrations considered herein. There was distinct evidence of adsorption of Cr(VI) ions during MEUF. The Langmuir adsorption equilibrium constant ( K ads ) for chromate ions was found out with the help of MEUF results. It was observed that at high feed concentration, the percent retention of chromate ions increases. However, the flux declined over a varying range of feed concentration (CPC and chromate ions). Further, at a much higher surfactant concentration (60 mM), the retention of chromate ions slightly decreased. The exclusive experimental runs with chromium ion solution showed an initial rapid decline of retention from 10 to 2.3% with increase in pressure.

Micellar Enhanced Ultrafiltration for Arsenic(V) Removal: Effect of Main Operating Conditions and Dynamic Modelling

In this work arsenic removal by micellar enhanced ultrafiltration (MEUF) was investigated using cetylpyridinium chloride (CPC) in ceramic membrane apparatus. Permeability tests and discontinuous diafiltration tests were performed in different operating conditions to evaluate the effect of membrane pore size (20 and 50 nm), transmembrane pressure, pH, surfactant concentration (1-3 mM), and arsenic concentration (10-40 mg/L) on permeate flux decline, arsenic, and CPC rejections. These preliminary experimental results showed that a ceramic membrane with large pore size allows treament of high fluxes of concentrated arsenic-bearing solutions even by using low surfactant concentrations. Arsenic concentration in the permeate was at the 1 ppm level, with feed As concentrations (10 ppm) that are larger than those generally used in MEUF studies and with CPC amounts that are lower than the usual ones. In addition, operating conditions adopted in these tests obtained CPC concentrations in the permeate always lower than its critical micellar concentration (0.9 mM). Dynamic simulations of discontinuous two-step diafiltration tests allowed a simple and adequate representation of the performance of the process especially for 1 mM CPC, while discrepancies for 2.5 mM CPC level denoted complex interactions between CPC and As.

Antimicrobial properties of an orthodontic adhesive combined with cetylpyridinium chloride

Patients undergoing fixed appliance treatment are at greater risk for increases in salivary and plaque levels of Streptococcus mutans and an elevated risk of dental caries. Cetylpyridinium chloride (CPC) is known to be an effective antiplaque agent. The purpose of this study was to investigate whether incorporating CPC into a commercially available orthodontic adhesive would impart antimicrobial properties without altering the diametral tensile strength of the material. CPC was added to a commercially available, filled, photo-activated bracket adhesive (Transbond XT, Unitek 3M, Monrovia, Calif) in varying amounts, to obtain specimens with CPC concentrations of 0% (control), 2.5%, 5.0%, and 10.0% by weight. Adhesive discs 2 mm thick and 4 mm in diameter were incubated with Streptococcus mutans for 48 hours. The diameters of the zones of bacterial inhibition were measured in an agar disc diffusion assay; specimens of each concentration were tested every other week for 196 days. Other discs were soaked in distilled water for 180 days. The amount of CPC released into the water from the modified discs was measured and recorded on days 7, 15, 30, 60, and 180 by using a spectrophotometer at 254 nm. Diametral tensile strength of the modified adhesive discs was measured with a universal testing machine, and the effect of water aging was also evaluated. The measured zone of bacterial inhibition increased as CPC content increased. All CPC-adhesive specimens maintained antimicrobial activity up to 196 days. No zone of bacterial inhibition was measured around the control specimens. CPC release was observed through the end of 180-day period, but the greatest release was recorded in the first week. There was no significant difference (P < .05) in diametral tensile strength between the 2.5% CPC-adhesive group and the control; there were significant differences among the 5.0% and 10.0% CPC-adhesive groups and the control. Water aging had no significant effect on diametral tensile strength other than decreasing it for the test group containing 10.0% CPC. The incorporation of 2.5% CPC in adhesive material imparted antimicrobial activity without altering diametral tensile strength.

Exploiting micellar environment for simultaneous electrochemical determination of ascorbic acid and dopamine

A simple and reliable method for simultaneous electrochemical determination of ascorbic acid (AA) and dopamine (DA) is presented in this work. It was based on the use of the cationic surfactant cetylpyridinium chloride (CPC) that enables the separation of the oxidation peaks potential of AA and DA. Cyclic voltammetry (CV) as well as pulse differential voltammetry (PDV) were used in order to verify the voltammetric behaviour in micellar media. In the cationic surfactant CPC, a remarkable electrostatic interaction is established with negatively charged AA, as a consequence, the oxidation peak potential shifted toward less positive potential and the peak current increased. On the other hand, the positively charged DA is repelled from the electrode surface and the oxidation peak potential shifts toward more positive potential in comparison to the bare electrode. Therefore, the common overlapped oxidation peaks of AA and DA can be circumventing by using CPC. Parameter that affects the E pa and I pa such as CPC concentration and pH were studied. Under optimised conditions, the method presented a linear response to AA and DA in the concentration range from 5 to 75 μmol L −1 and 10 to 100 μmol L −1, respectively. The proposed method was successfully applied to the simultaneous determination of AA and DA in dopamine hydrochloride injection (DHI) samples spiked with AA.

Cetylpyridinium Chloride as a Regulator in Paper Separation of 2,4-Dichlorophenol and 2,4,6-Trichlorophenol in Water

2,4-Dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) by the use of cetylpyridinium chloride (CPC1) as a regulator was studied for their separation by the paper capillary permeation adsorption (PCPA) separation technique. The effect of pH, the type of PCPA treatment, the concentration of cetylpyridinium chloride, and various inorganic salts on the separatability has been investigated. A nearly 100% separatability was obtained at pH values 5-11 and 5-11, respectively, for 2,4-dichlorophenol and 2,4,6-trichlorophenol when cetylpyridinium chloride was present. It was confirmed that 2,4-dichlorophenol and 2,4,6-trichlorophenol are separated by adsorption on the fiber surface as ion pairs at the pH. Addition of inorganic salts decreases the separatability.

Effect of salt on the micelles of cetyl pyridinium chloride

Surface tension, conductance, viscosity, dynamic light scattering (DLS) and small angle neutron scattering (SANS) measurements were carried out in order to investigate the effect of added salt NaCl and NaBr on micellization and structure of cetylpyridinium chloride (CPyCl) micelles. Critical micelle concentration (CMC) of CPyCl decreases with increase in salts concentration, while CMC and counter ion dissociation ( β) increases with increase in temperature. At a given CPyCl concentration, the micelle size increases with increasing salt concentration above a threshold value. Micellar growth in presence of salts is clearly reflected by an increase in viscosity, hydrodynamic diameter ( d) from DLS and aggregation number from SANS measurements. The effect of NaBr on CPyCl micelles was more pronounced in comparison to NaCl. The difference in solution properties of Br − and Cl − is that Cl − counter ions being more hydrated are less effective to neutralize the charge on the micellar surface.

Antimicrobial finishing of acrilan fabrics with cetylpyridinium chloride

AbstractDurable antimicrobial properties could be achieved on acrilan fabrics by chemically incorporating biocidal quaternary ammonium salts such as cetylpyridinium chloride (CPC) into the fibers. The chemical interactions between CPC and acrilan fibers were investigated through adsorption isotherm and exhaustion rates of CPC on the fabrics under various conditions. The equilibrium adsorption of CPC on the acrilan fabrics was in good agreement with the Langmuir adsorption isotherm. The study found that CPC concentration, pH value, and finishing temperature and time affected the adsorption process and antimicrobial properties of the acrilan fabrics. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 243–247, 2004

Inactivation kinetics of mushroom tyrosinase by cetylpyridinium chloride.

Cetylpyridinium chloride (CPC) was found to inactivate tyrosinase from mushroom (Agaricus bisporus). CPC can bind to the enzyme molecule and induce the enzyme conformation changes. The fluorescence intensity (at 338.4 nm) of the enzyme decreased distinctly with increasing CPC concentrations, and a new little fluorescence emission peak appeared near 372 nm. The inactivation of the enzyme by CPC had first been studied by using the kinetic method of the substrate reaction described by Tsou. The results showed that the enzyme was inactivated by a complex mechanism that had not been previously identified. The enzyme first quickly binds with CPC reversibly and then undergoes a slow irreversible inactivation. The inactivation reaction is a single molecule reaction and the apparent inactivation rate constant is a saturated trend being independent of CPC concentration if the concentration is sufficiently high. The micro rate constants of inactivation and the association constant were determined.

Influence of Surfactants on the Rate of Decomposition of Apatites by Mineral Acids

The dependence of the true rate of decomposition of fluorapatite and hydroxylapatite in nitric, sulfuric, and orthophosphoric acids on the concentration of a surfactant (cetylpyridinium chloride and sodium dodecyl sulfate) was experimentally studied. The electrokinetic potential in the slip plane of the double electric layer at the interface between apatite and an aqueous solution of a surfactant was measured by the electroosmotic method. The concentrations of cetylpyridinium chloride (5.5 × 10–6 mol/l) for fluorapatite and sodium dodecyl sulfate (1 × 10–4 mol/l) for hydroxylapatite were found, which correspond to the isoelectric state of the surface of the solid phase. It was established that the true rate of decomposition of apatites is maximal when the electrokinetic potential is zero.

A novel pharmacological probe links the amiloride-insensitive NaCl, KCl, and NH(4)Cl chorda tympani taste responses.

Chorda tympani taste nerve responses to NaCl can be dissected pharmacologically into amiloride-sensitive and -insensitive components. It is now established that the amiloride-sensitive, epithelial sodium channel acts as a sodium-specific ion detector in taste receptor cells (TRCs). Much less is known regarding the cellular origin of the amiloride-insensitive component, but its anion dependence indicates an important role for paracellular shunts in the determination of its magnitude. However, this has not precluded the possibility that undetected apical membrane ion pathways in TRCs may also contribute to its origin. Progress toward making such a determination has suffered from lack of a pharmacological probe for an apical amiloride-insensitive taste pathway. We present data here showing that, depending on the concentration used, cetylpyridinium chloride (CPC) can either enhance or inhibit the amiloride-insensitive response to NaCl. The CPC concentration giving maximal enhancement was 250 microM. At 2 mM, CPC inhibited the entire amiloride-insensitive part of the NaCl response. The NaCl response is, therefore, composed entirely of amiloride- and CPC-sensitive components. The magnitude of the maximally enhanced CPC-sensitive component varied with the NaCl concentration and was half-maximal at [NaCl] = 62 +/- 11 (SE) mM. This was significantly less than the corresponding parameter for the amiloride-sensitive component (268 +/- 71 mM). CPC had similar effects on KCl and NH(4)Cl responses except that in these cases, after inhibition with 2 mM CPC, a significant CPC-insensitive response remained. CPC (2 mM) inhibited intracellular acidification of TRCs due to apically presented NH(4)Cl, suggesting that CPC acts on an apical membrane nonselective cation pathway.

Flux and retention analysis during micellar enhanced ultrafiltration for the removal of phenol and aniline

Studies were done for the removal of organic solutes under aqueous medium through micellar enhanced ultrafiltration (MEUF). The organic solutes selected for experiments consisted of an ionic compound (phenol) and a non-ionic compound (aniline); whereas cetyl pyridinium chloride (CPC), a counter-ionic surfactant was used for the formation of micelles under aqueous medium. UF was carried out under both stirred and unstirred conditions using batch cells. The effect of important operating parameters (applied pressure, solutes and surfactant bulk concentrations) on the extent of separation of the organic solutes were observed and studied. Solubilization of these solutes in CPC micelles were also experimentally ascertained. A mathematical model developed in this study was used to describe the separation of organic solutes by MEUF and predict permeate solute concentrations under varying operating conditions. The effect of pressure and feed CPC concentration on the behaviour of permeate flux was explained as a consequence of the formation of concentration polarized layer of CPC, upstream of the membrane surface. The removal of organic solutes (phenol and aniline) were observed to increase with increase in feed CPC concentration; however, upto about 150 mM, beyond which it was more or less constant. Solubilization equilibrium constant of phenol in CPC micelles was estimated to be around four times that of aniline.

Micellization of Cetylpyridinium Chloride Using Conductometric Technique

Conductometric technique has been used to investigate the equilibrium properties of cetylpyridinium chloride (CPC) in the presence of a series of aliphatic alcohols. The dependence of conductivity of surfactant solution in the presence of particular amount of alcohol has been studied. According to the experimental results, ethanol cause to decrease the dielectric constant and conductivity of micellar solution. Alcohols with longer chain may change the conductivity of solution depend on concentration of surfactant. At low concentration of CPC near critical micelle concentration (cmc) region, the minimum value of conductivity can be observed. This minimum value can be controiled by decreasing of free monomer concentration and also increasing degree of dissociation of micelle because of penetration of alcohols in micellar core. Using Conductometric technique cmc and α (degree of dissociation of counterion) of CPC were evaluated. The micelle formation of CPC has been considered in ethylene glycol (E.G)/ water and glycerol/water mixtures. It has been shown, the logarithm of cmc is directly depended on the ratio of E.G/water or glycerol/water.

Spectrophotometric study of interaction in the system sodium dodecyl sulfate-cetylpyridinium chloride-methylene blue

Complexation of a cationic dye (Methylene Blue) with anionic and cationic surfactants (sodium dodecyl sulfate and cetylpyridinium chloride) was studied spectrophotometrically. The formation constants of complexes formed in the system were estimated. Dispersion of the investigated system was studied as a function of time and cetylpyridinium chloride concentration.

Interaction of Polystyrene-block-poly(ethylene oxide) Micelles with Cationic Surfactant in Aqueous Solutions. Metal Colloid Formation in Hybrid Systems

The interaction of the amphiphilic block copolymer, polystyrene-block-poly(ethylene oxide) (PS-b-PEO), with cationic surfactant, cetylpyridinium chloride (CPC), in aqueous media was studied by static light scattering and analytical ultracentrifugation. Three well-defined populations of hybrid structures corresponding to micelles, micellar clusters, and supermicellar aggregates were found to exist in the PS-b-PEO/CPC aqueous solutions at a block copolymer concentration of 10 g/L. The relative ratio of each type of structure and their parameters strongly depend on the CPC concentration, mobility of the polystyrene micellar core, and chemical composition of the dispersing media. Ion exchange of the surfactant counterions in the hybrid PS-b-PEO/CPC system by PtCl62- and PdCl42- ions resulted in saturation of the micellar structures with noble metal ions. The subsequent reduction of the metal-containing PS-b-PEO/CPC/MXn species with NaBH4 and molecular hydrogen resulted in the formation of metal nanoparticles ...

Spectroscopic Investigations in Molecularly Organized Solvent Media. Part 4. Effect of Cosurfactant On the Ability of the Cetylpyridinium Cation to Selectively Quench Fluorescence Emission of Alternant Versus Nonalternant Polycyclic Aromatic Hydrocarbons

Fluorescence behavior is reported for 12 alternant and 15 nonalternant polycyclic aromatic hydrocarbons (PAHs) dissolved in aqueous micellar cetyltrimethylammonium bromide (CTAB) + cetylpyridinium chloride (CPC), Brij-35 + CPC and sodium dodecyl-sulfate (SDS) + CPC mixed surfactant solvent media. the three cosurfactants studied contain a cationic, nonionic and anionic headgroup, respectively. Experimental measurements indicate that the cetylpyridinium cation selectively quenches fluorescence emission of alternant PAHs. Emission intensities of nonalternant PAHs, with a few noted exceptions, remain essentially constant, irrespective of both CPC concentration and cosurfactant headgroup charge.

High-performance liquid chromatography determination of residue levels on chicken carcasses treated with cetylpyridinium chloride

Cetylpyridinium chloride (CPC) has been found to be effective in reducing contamination of chicken carcasses from a variety of microorganisms, including Escherichia coli O157:H7, Salmonella typhimurium, Campylobacter jejuni, Aeromonas hydrophila, Listeria monocytogenes, and Staphylococcus aureus. A procedure has been developed to determine residue levels on chicken carcasses after CPC treatment. For the analysis, chicken carcasses were extracted with 95% ethanol. The CPC concentration in the extract was measured by high-performance liquid chromatography (HPLC) with ultraviolet detection using dodecylpyridinium chloride (DPC) as an internal standard. The method was validated in the concentration range of 3–200 μg/ml CPC in ethanolic extract. This assay is rapid, precise, and accurate.

Theory and experiment of reversing-pulse electric birefringence: The case of bentonite suspensions in the absence and presence of cetylpyridinium chloride

Reversing-pulse electric birefringence (RPEB) of a fractionated bentonite sample (0.005–0.029 g/l) was measured at 20°C and at a wavelength of 633 nm in aqueous media in the absence and in the presence of cetylpyridinium chloride (CPC), a surfactant, at various concentrations (0.001–1.3 mM). RPEB signals at weak electric fields showed either a hump each, or contrarily a dip each, in the build-up and reverse portions, depending on the concentrations of bentonite and CPC in suspension. The profile change of RPEB signals was interpreted as being due to the shift of the orientation axis from the symmetry axis to the plane of the disk-like particle. Observed RPEB signals were analyzed with the Y–S–K theory, which is based on an ion-fluctuation model and considers the contribution of three electric dipole moments to field orientation, and both electric and hydrodynamic parameters characteristic of RPEB profiles were evaluated by curve fitting with theoretical equations. The results are as follows: (1) the bentonite particle in the absence or in the presence of CPC possesses no permanent dipole moment; (2) it is oriented by applied field with the root-mean-square dipole moment due to ion-atmosphere fluctuation and the covalent dipole moment due to the polarizability anisotropy intrinsic to the particle; (3) the ratios of these two dipole moments either remain nearly constant or vary in a complex manner, depending on bentonite concentration, amount of added CPC, and field strength; and (4) the ratios of the relaxation time due to ion-fluctuation to the relaxation time due to overall particle rotation remain nearly constant for the bentonite suspension in the absence of CPC with increasing field strengths, though the system is polydisperse.

Recovery and purification of thuringiensin from the fermentation broth of Bacillus thuringiensis

Thuringiensin is a heat stable β-exotoxin from Bacillus thuringiensis with a great potential for replacing the traditional chemical pesticides. A process using micellar-enhanced ultrafitration method to recover thuringiensin was significantly improved by the use of a spiral-wound membrane, which could be operated at a low transmembrane pressure drop. This method was performed by adding a surfactant cetylpyridinium chloride (CPC) into the fermentation broth. After the surfactant-thuringiensin conjugates were formed, the broth then passed through the ultrafiltration membrane and the retentate was collected. The results indicated the optimal concentration of CPC for producing a maximal recovery up to 99.3% is 4%. For purification, the centrifuged broth was further filtered by a membrane filter. The filtered solution then was mixed with 50% of activated carbon. The supernatant then was injected into a preparative HPLC. The eluate was collected during thuringiensin peak formation. This eluate was then concentrated by vacuum evaporation and dialysis using an electrodialyzer to remove the excess salts. The dialyzed solution was then crystallized by lyophilization. The purity of the thuringiensin crystal was identified by HPLC, capillary electrophoresis, and mass spectrometry.

Surface Electric Properties of the Na-Bentonite/Cetylpyridinium Chloride System as Studied by Reversing-Pulse Electric Birefringence

The adsorption of a cationic surfactant, cetylpyridinium chloride (CPC), on disklike Na-bentonite particles has been studied in very dilute suspensions by reversing-pulse electric birefringence (RPEB). The electric parameters of the particle/surfactant system were evaluated from signals taken at extremely low degrees of orientation by using the ion-fluctuation RPEB theory. The electric field orientation of the particles was found to result from the simultaneous action of the polarizability anisotropy Δα′ and the ion-atmosphere polarizability α3caused by ion fluctuation. Two different CPC concentration ([CPC]) ranges could be distinguished according to the magnitude of the induced dipole moment of the particles. When [CPC] was lower than 0.01 mM, the orientation of the particles was mainly due to the covalent polarizability anisotropy Δα′. When [CPC] was higher than 0.01 mM, the ionic polarizability α3was predominant over Δα′, the particles being oriented with the symmetric axis parallel to the direction of the electric field. Values of the electric parameters of the particles changed upon reversal of the sign of the applied reversing-pulse electric field. The change was probably due to the reordering and/or redistribution of the multilayer structure of adsorbed CPC molecules. Such effects were negligible below the critical [CPC] of 0.01 mM, where the adsorbed molecules may form a loose monolayer on the bentonite surface.

Elimination of Salmonella Contamination from Poultry Tissues by Cetylpyridinium Chloride Solutions

The effects of cetylpyridinium chloride (CPC) on the inhibition and reduction of viable Salmonella typhimurium cells were studied. In these experiments skin excised from chicken drumsticks was treated with solutions of CPC. At the CPC concentrations used, the ability of this compound to reduce bacterial contamination was clearly demonstrated. This effect was both CPC concentration- and exposure-time-dependent. A 4.87-log reduction of viable S. typhimurium cells was achieved at a CPC concentration of 4 mg/ml at the treatment time of 3 min. Moreover, CPC was effective in preventing bacterial contamination, as shown by a 4.9-log inhibition of S. typhimurium cell attachment at a CPC concentration of 8 mg/ml and a treatment time of 10 min.