Cetyldimethylbenzylammonium Chloride Research Articles

Determination of residual bendiocarb in environmental samples using magnetic nanoparticles modified with cetyldimethylbenzylammonium chloride by UV-Vis spectrophotometry

ABSTRACT Bendiocarb (BEN), a highly toxic carbamate insecticide used in agriculture, is effective against various nuisance and disease vector insects. Utilizing Fe3O4 magnetic nanoparticles coated with cetyldimethylbenzylammonium chloride (CDMC), a simple and sensitive solid-phase microextraction technique has been devised for the preconcentration and determination of BEN at trace levels in environmental samples. Fe3O4@CDMC nanoparticles (NPs) were utilised as the magnetic solid-phase extraction agents. The azo-dye produced between BEN and the diazotised procaine benzylpenicillin (drug compound) adsorbed on the NPs was eluted using ethanol and quantified spectrophotometrically at wavelength 456 nm. Experimental factors impacting the extraction efficiency of the method were optimised: the amount of surfactant (1 mg) and the sorbent (30 mg), type and volume of base (sodium hydroxide, 2 mL), type and volume of eluent (ethanol, 1 mL), and extraction time (15 min). The relative standard deviation (RSD%) of the method was investigated and it ranged from 1.8–4.2% (n = 5). Upon optimisation, BEN could be concentrated from different samples 50-fold with an enrichment factor of 72. The linear range, correlation coefficient (R) and detection limit could reach 0.03–1.5 µg/mL, 0.9984 and 0.01 µg/mL, respectively. The technique has been effectively verified for detecting bendiocarb in various environmental samples.

Study on preparation and mechanism of organic montmorillonite with different functional groups

The influence of functional groups on the organic intercalation of montmorillonite (Mt) was discussed in this article by intercalating Mt with four organic compounds containing different cationic functional groups. The maximum intercalation amounts of hexadecyl trimethyl ammonium bromide (CTAB), benzylcetyldimethyl ammonium chloride (HDBAC), bromohexadecyl pyridine (HIB), and 1-hexadecyl-3-methylimidazolium chloride (HMC) were 0.96, 0.81, 0.73, and 0.61 mmol/g, respectively. Molecular simulations revealed that the functional groups influenced the arrangement status of organic cations in the Mt interlayers. It found out that the minimum distances between the nitrogen atom in CTAB, HDBAC, HIB, and HMC and the surface oxygen of Mt were 2.939 ± 0.05, 2.554 ± 0.11, 3.703 ± 0.07, and 3.360 ± 0.08 Å, respectively. Molecular size was also shown to influence intercalation since CTAB was more easily intercalated than the larger HDBAC. Moreover, the benzene ring in HDBAC weakened the interaction between its chains, which decreased its intercalation amount. The –N+ functional groups of HIB and HMC were located on the benzene ring, which weakened their cationic exchange ability. In summary, the functional groups affected the intercalation amount, intercalation rate, and their arrangement (parallel or vertical) in Mt. These results were used to explore the intercalation mechanism of Mt, which can be used to guide the production of novel organic Mt compounds.

Study on the Surface Properties and Aggregation Behavior of Quaternary Ammonium Surfactants with Amide Bonds.

A number of techniques, including conductivity, surface tension, dynamic light scattering, transmission electron microscopy, and 1H nuclear magnetic resonance (1H NMR), Fourier transform infrared (FT-IR), and 1H–1H 2D nuclear Overhauser effect spectroscopy (1H–1H 2D NOESY), have been used to investigate the effect of amide bonds on the interfacial and assembly properties of a cationic surfactant, N-anilinoformylmethyl-N-cetyl-N,N-dimethyl ammonium chloride (AMC-C16), in aqueous solutions. The adsorption of AMC-C16 has been found to be much better than that of the conventional cationic surfactant, benzyl cetyldimethylammonium chloride (BAC-16) at the air/water interface and in solution. The surface tension measurements show the presence of two critical aggregation concentrations (CAC1 and CAC2) for AMC-C16. The presence of a strong intermolecular hydrogen bond of AMC-C16 was confirmed by 1H NMR and FT-TR. The molecular interactions of AMC-C16 were detected by 1H–1H 2D NOESY. The results show that the rigid group (phenyl) of AMC-C16 was partially overlapped with its alkyl chain in aqueous solution, and the possible aggregation behavior for AMC-C16 was proposed. The effects of an inorganic salt (NaCl) and an organic salt (C6H5COONa) to the aggregates of AMC-C16 have been discussed.

A Seedless Method for Gold Nanoparticle Growth inside a Silica Matrix: Fabrication of Materials Capable of Third-Harmonic Generation in the Near-Infrared.

A composite in which gold nanoparticles (AuNPs) approximately 10 nm in size are embedded in amorphous transparent silica matrix has been produced. The synthetic protocol uses HAuCl4 as the Au ion source, tetraethoxysilane (TEOS) as the SiO2 precursor, and l-ascorbic acid (AA) as the reducing agent. AA is employed before the sol-gel process in an amount sufficient only for reduction of Au3+ ions to Au+ . By using a cationic surfactant, benzylcetyldimethylammonium chloride hydrate (BDAC) and/or cetyltrimethylammonium bromide (CTAB), the Au+ ions are encapsulated within metalomicelles, which prevents them from being reduced to Au0 and enables their homogeneous distribution in the gel. Reduction of Au+ to Au0 and the growth of the AuNPs occurs at room temperature during the gelation, and arises from the release of EtOH during the hydrolysis of TEOS. The composites contain 0.027 wt % of Au. They exhibit nonlinear optical behavior characterized by the third-order nonlinear refraction index, n2 , in the range 3.6-5.7×10-16 cm2 W-1 at λ=1.030 μm. The composites are capable of effective third-harmonic generation of ultrashort near-IR (210 fs, 1.030 μm) laser pulse through a direct third-order mechanism.

Influence of organic solvents and temperature on the micellization of conventional and gemini surfactants: a conductometric study

ABSTRACTThe micellar behaviour of similar hydrophobic chain length conventional (cetyltrimethyl ammonium bromide, CTAB; cetyl pyridinium chloride, CPC; cetyldimethylbenzyl ammonium chloride, C16BCl) and gemini surfactant (16-2-16) in water and polar non-aqueous solvents has been investigated in the temperature range 288.15–318.15 K with the help of conductivity measurements. The method proposed by Carpena et al. has been used to analyse the conductivity–concentration to determine the micellization parameters using critical micelle concentration (CMC) and degree of counter-ion dissociation (α) of the micelle. It shows much better performance than the conventional methods and the effect of experimental errors on the evaluation of the micellization parameters has been shown to be minimal by using this procedure. It was observed that the micellization tendency of the surfactant decreases in the presence of solvents. Thermodynamic parameters were also evaluated from the temperature dependence of the CMC values.

Feasibility of using a standardized Caenorhabditis elegans toxicity test to assess nanomaterial toxicity.

Increasing production and use of engineered nanomaterials (ENMs) has generated widespread interest in measuring their environmental and human health effects. However, the lack of standardized methods for these measurements has often led to contradictory results. Our goal in this study was to examine the feasibility of using a standardized Caenorhabditis elegans growth and reproduction based toxicity test designed for use with dissolved chemicals to assess ENM toxicity. Sensitivity testing of seven key experimental factors identified by cause-and-effect analysis revealed that bacterial feed density and plate shaking had significant effects on growth inhibition by a reference toxicant, benzylcetyldimethylammonium chloride (BAC-C16). Bacterial density was inversely proportional to experimental EC50 values, while shaking the plates during the assay caused a substantial decrease in nematode growth and reproduction in control nematodes. Other factors such as bacterial viability, organism maintenance, and media type showed minimal effect on the test method. Using this assay with positively charged polystyrene nanoparticles (PSNPs) revealed that the variability in the PSNP EC50 values was larger compared to those of BAC-C16. Additionally, while media type and bacterial viability did not impact BAC-C16 toxicity, PSNP toxicity differed substantially when these parameters were changed. PSNPs were more toxic in K+ medium and S-basal compared to M9 and feeding nematodes with UV killed E. coli decreased toxicity of PSNPs. Test validity with ENMs and modifications that can be made to adapt the standard C. elegans toxicity assay for use with ENMs are discussed.

Hollow mesoporous Ia3d silica nanospheres with singleunit-cell-thick shell: Spontaneous formation and drug delivery application

Mesoporous silica nanoparticles (MSNs) are promising for drug delivery and other biomedical applications owing to their excellent chemical stability and biocompatibility. For these applications, a hollow morphology with thin shell and open mesopores is preferred for MSNs in order to maximize the loading capacity of drugs. Herein we report a novel and direct synthesis of such an ideal drug delivery system in a dilute and alkaline solution of benzylcetyldimethylammonium chloride and diethylene glycol hexadecyl ether. The mixed surfactants can guide the formation of MSNs with cubic Ia3d mesostructure, and at a concentration of sodium hydroxide between 9.8 and 13.5 mM, hollow MSNs with uniform sizes of 90–120 nm and a single-unit-cell-thick shell are formed. A mechanism for the formation of the hollow Ia3d MSNs, designated as MMT-2, is proposed based on in situ small-angle X-ray scattering measurements and other analyses. MMT-2 exhibits much higher loading capacity of ibuprofen and degrades faster in simulated body fluid and phosphate buffered saline than non-hollow MSNs. The degradation of MMT-2 can be significantly retarded by modification with polyethylene glycol. More interestingly, the degradation of MMT-2 involves fragmentation instead of void formation, a phenomenon beneficial for their elimination. The results demonstrate the uniqueness of the hollow Ia3d MSNs and the great potential of the material for drug delivery and biomedical applications.

New Synthesis of MCM-48 Nanospheres and Facile Replication to Mesoporous Platinum Nanospheres as Highly Active Electrocatalysts for the Oxygen Reduction Reaction

Self-supported mesoporous Pt nanospheres are prepared by the templated method for the electrocatalytic oxygen reduction reaction (ORR). Single-crystal-like MCM-48 nanospheres, synthesized via a new and simple route in a dilute and alkaline solution of benzylcetyldimethylammonium chloride, are applied as the hard template. A facile process of molten salt impregnation followed by hydrogen reduction is developed to replicate both the mesostructure and morphology of the hard template and to form mesoporous Pt nanospheres. The high-surface-area mesoporous Pt nanospheres are thermally stable in air up to 300 °C without showing significant metal sintering. Electrocatalytic studies reveal that mesoporous Pt nanospheres have a large fraction of {110} facets and exhibit high activity for the ORR. The excellent electrocatalytic performance may be mainly attributed to the facet-dependent ORR activities as well as the presence of 3D interconnected mesopores to facilitate mass transport.

Polydiacetylenes Bearing Boronic Acid Groups as Colorimetric and Fluorescence Sensors for Cationic Surfactants

A new polydiacetylene oxyphenylboronic acid (PDA-OPBA-1) bearing group was synthesized and showed diverse colorimetric changes, such as yellow, orange, and red, upon the addition of cationic surfactants at pH 7.4. On the other hand, anionic surfactants and simple ammonium salts did not show any color change. Specifically, color changes to yellow for cetyl trimethylammonium chloride (CTAC), red for dodecyl trimethylammonium bromide (DTAB), orange for benzylcetyldimethylammonium chloride (BCDA), and dark orange for hexadecylpyridium bromide (HDPB) are observed, respectively. Different head groups and alkyl chain lengths of cationic surfactants can be intelligently distinguished via a unique penetration process.

Adsorption of cationic surfactants on covered hanging mercury drop electrode surface of variable area

Cetyldimethylbenzylammonium chloride (CDBACl) or cetyltrimethylammonium bromide (CTAB) is preadsorbed on mercury and used as substrate. The adsorptive stripping voltammetry with the two-step procedure is used. The mercury droplet with the preadsorbed surfactant is expanded in aqueous solutions of KCl, KBr, CTAB, CDBACl, or cetylethyldimethylammonium bromide (CEDAB). The surface area was increased from 0.0022cm2 up to 0.0571cm2. The surfactant molecules are maintained close to each other and in the vicinity of the electrode by the applied electric field. The expanding of the droplets resulted in a reorientation of the adsorbed molecules depending on the surfactant surface concentration. In some cases, condensed films were observed. Differences were noticed in the adsorption and desorption potential region. A linear increase in the capacitance current with the surface area was found in all cases up to a maximum increase in the surface area. Partly disorganized films were also observed. In some cases, defects were noticed during expansion. In one case, fractal structure was observed.

Interlaboratory comparison of a standardized toxicity test using the nematode Caenorhabditis elegans (ISO 10872)

A ring test was carried out within the standardization process of ISO 10872 to evaluate the precision of the toxicity test for the nematode Caenorhabditis elegans. Eight different laboratories tested aqueous solutions of the reference substance benzylcetyldimethylammonium chloride as well as native sediments and soils for toxic effects on the growth and reproduction of C. elegans. Validity criteria were met in all laboratories. Average median- and low-effect concentrations were determined to be 15.1 mg L(-1) (EC50) and 8.7 mg L(-1) (EC10) for growth and 7.5 mg L(-1) (EC50) and 3.8 mg L(-1) (EC10) for reproduction of C. elegans, with ECx values showing a high degree of reproducibility (CV(R) : <21% and <11% for EC10 and EC50, respectively) and repeatability (CV(r) : <20% and <7% for EC10 and EC50, respectively). The toxic effects of the sediments and soils revealed by the different laboratories were well related to each samples' degree of chemical contamination. Moreover, the effects showed an acceptable reproducibility (CV(R) : 5-33% and 0-28% for growth and reproduction, respectively) and repeatability (CV(r) : 3-13% and 0-12% for growth and reproduction, respectively). The present study confirms that the toxicity test with C. elegans according to ISO 10872 is a reliable and precise tool to assess the toxicity of aqueous media, freshwater sediments, and soils.

Mixed Micellization Behavior of m‐2‐m Gemini Surfactants with Some Conventional Surfactants at Different Temperatures

AbstractMixed micellization behavior of dimeric cationic surfactants ethanediyl‐1,2‐bis(dimethyl alkyl ammonium bromide) (m‐2‐m where m = 10, 12) with conventional single chain cationic surfactants like cetyltrimethyl ammonium bromide (CTAB), cetylpyridinium chloride (CPC), tetradecyl dimethyl benzyl ammonium chloride (C14BCl) and cetyl dimethyl benzyl ammonium chloride (C16BCl) were studied in aqueous and aqueous polyethylene glycol (PEG) solutions at 298.15, 308.15 and 318.15 K respectively using conductometric and viscometric methods. In aqueous solutions, all the combinations (except 12‐2‐12 + CTAB) were found to behave nonideally with mutual synergism which decreases with increase in temperature. Various thermodynamic parameters of micellization like , and were evaluated and discussed. Similarly in presence of PEG, the thermodynamic properties like , and associated with the transfer of surfactant monomers from the medium consisting of polymer‐free mixed micelles to polymer‐bound mixed micelles at various temperatures were also calculated. The negative values of show that aggregation process is more exothermic than micellization whereas the negative values of indicate that the presence of polymer bound mixed micelles decreases the degree of randomness of the system. Viscosity studies show that in aqueous solutions all the combinations of 10‐2‐10/12‐2‐12 display negative departure in the relative viscosity (ηr) from additivity rule which decreases with increase in temperature. Similarly in the presence of 5% PEG solutions the magnitude of the negative departure decreases for all the combinations and becomes positive in the case of C14BCl and CPC combinations with the studied gemini surfactants at higher temperatures.

Adsorption of cetyltrimethylammonium bromide and/or cetyldimethylbenzylammonium chloride on partly covered hanging mercury drop electrode

Adsorbed cetyldimethylbenzylammonium chloride (CDBACl) or cetyltrimethylammonium bromide (CTAB) on mercury is used as template for the adsorption of CTAB, CDBACl, or their equimolar mixture at 20°C. Adsorptive stripping voltammetry with the two step procedure is used. The results are compared with previously published results on the adsorption of CTAB and CDBACl on mercury and then transferred in base electrolyte. A surfactant is preadsorbed. The adsorption of the second does not remove away from the mercury the first one, as evidenced by the capacitance measurements and the repeated scans. The surfactants were maintained close to each other and in the vicinity of the electrode by the applied electric field. In all cases studied, there was a decrease in the capacitance in the potential range −0.8 to −1V to very low capacitance values forming condensed film. Mixed films and synergy effects were observed. The already adsorbed CTAB on mercury did not permit the desorption–reorientation peaks of CDBACl. Shifts of the capacitance peaks were observed to more positive potentials and were attributed to the occurrence of a slow change in the organization of the monolayer. The electrical state of the preadsorbed surfactant would be of critical importance in the formation of the various structures. The results suggested that the ordering and arrangement of molecules could be controlled by appropriate selection of templates.

Adsorption of cetyltrimethylammonium bromide and cetyldimethylbenzylammonium chloride on a hanging mercury electrode studied by adsorptive transfer stripping voltammetry

The adsorption of cetyltrimethylammonium bromide (CTAB) and cetyldimethylbenzylammonium chloride (CDBACl) on a hanging mercury electrode is studied using adsorptive transfer stripping voltammetry. The surfactants are adsorbed on mercury and are then transferred in KBr or KCl under various conditions, including temperatures from 1 to 40°C, open or closed circuits with different initial potentials, and repeated scans, etc. The results are compared with previously published results on the adsorption of CTAB or CDBACl on mercury, where condensed films were formed and are quite different than those obtained by adsorptive stripping voltammetry. In this case, an absence of condensed film is observed for CTAB. A condensed film with low capacitance value is formed in the case of CDBACl after transfer at low temperatures, or after repeated scans, resulting in reorientation of the molecules to more compact states. Capacity time curves at the potentials where the film is formed show in a few cases a nucleation and growth mechanism, with induction time and studied by the Avrami formulation, while an observed increase of the capacitance with time is attributed to the formation of hemimicelles. The results also indicate the importance of interactions between the hydrophobic chains.

Micellization Behavior of the 14‐2‐14 Gemini Surfactant with Some Conventional Surfactants at Different Temperatures

AbstractMixed micellization behavior of the dimeric cationic surfactant ethanediyl‐1,2‐bis(dimethyl tetradecyl ammonium bromide) with monomeric cationic surfactants cetyltrimethyl ammonium bromide (CTAB), cetylpyridinium chloride (CPC), tetradecyl dimethyl benzyl ammonium chloride (C14BCl) and cetyl dimethyl benzyl ammonium chloride (C16BCl) was studied in aqueous and aqueous polyethylene glycol (PEG) solutions at various temperatures (298.15, 308.15 and 318.15 K) using conductometric and viscometric methods. The behavior of these mixed systems was analyzed in light of Rubingh's regular solution theory. The conductivity study indicates that the above systems behave nonideally with mutual synergism at 298.15 and 308.15 K, whereas antagonistic behavior is exhibited at 318.15 K. In the presence of PEG solution, various thermodynamic parameters associated with transfer of surfactant monomers from the medium consisting of polymer‐free mixed micelles to polymer‐bound mixed micelles like ∆Gto, ∆Hto and ∆Sto at various temperatures were evaluated and discussed. The viscosity study shows that in aqueous solutions all these combinations exhibit significant negative departure in the relative viscosity (ηr) from the additivity rule at 298.15 and 308.15 K, whereas at 318.15 K these combinations (except in the case of C14BCl) follow the additivity rule. In presence of 5% PEG solution, all the combinations show positive departure from the additivity rule except the combination with C14BCl which shows negative departure at all the studied temperatures.

Ammonium detection by formation of colored zebra-bands in a detecting tube

Ammonium ion was colorized by means of a diazo coupling reaction with 2-phenylphenol, where the color development reaction was conducted within 3min by using boric acid as a catalyst. The resulting colored solution (0.5ml) was supplied by suction to a detecting tube consisting of a nonwoven fabric test strip (2mm wide, 1mm thick, 150mm long) impregnated with benzylcetyldimethylammonium chloride in a stripe pattern and enclosed in a heat-shrinkable tube. When the colored solution was supplied to the detecting tube, blue zebra-bands formed, and the ammonium concentration was determined by counting the number of zebra-bands. The detection range was 1-20mg-Nl(-1). Ammonium ion in actual domestic wastewater samples was successfully detected by means of this method.

Kinetics of Phase Transfer Agent-aided Free–Radical Polymerization of Acrylonitrile and Methyl Methacrylate Using Water-Soluble Initiator

This paper deals with the kinetics of radical polymerization of acrylonitrile (AN) and methyl methacrylate (MMA), using water-soluble potassium peroxydisulphate initiator in the presence of cetyldimethylbenzylammonium chloride (PTC), at 60°C under oxygen-free atmosphere. The role of concentrations of monomer, initiator, catalyst and temperature on the rate of polymerization were ascertained. Based on the results obtained, a suitable kinetic scheme has been proposed to account for the experimental observation.

Influence of surfactants on the fading of malachite green

Abstract The kinetics of the reaction between malachite green (MG) and sodium hydroxide (MG fading) was studied using a spectrophotometric method in the presence of two cationic surfactants, cetyl-benzyl-dimethyl-ammonium chloride (CBDAC) and hexadecyl-trimethylammonium bromide (HTAB) and one anionic surfactant, sodium dodecyl sulphate (SDS) at concentrations below and above critical micellar concentrations. The cationic surfactants have a catalytic effect, while the anionic surfactant has an inhibitory effect on the reaction. A kinetic model describing the influence of surfactant on reaction rate was developed. The results are discussed on the basis of electrostatic and hydrophobic interactions between the kinetic micelles and malachite green.

Effect of deaeration on the adsorption of a mixture of cetyltrimethylammonium bromide and cetyldimethylbenzylammonium chloride at the mercury/electrolyte solution interface

The effect of deaeration on the adsorption of a mixture of cetyltrimethylammonium bromide and cetyldimethylbenzylammonium chloride at the mercury/electrolyte interface solution is studied using capacitance measurements focusing mainly at very low temperatures. Isochronous capacitance vs potential curves reconstructed from capacitance time curves show that the deaeration depends on the type of inert gas used as well as the deaeration process. The deaeration changes mainly the kinetics of the change of the capacitance with time. In cases where a condensed film is formed, the equilibrium capacitance value does not change with deaeration, indicating that the organization of the surfactants at the interface is not connected with the deaeration. The effect is attributed to the removal of dissolved gases from water.

Modified hectorites and adsorption studies of a reactive dye

Hectorite has been modified by two different cationic surfactants namely cetyldimethyl benzylammonium chloride and cetylpyridinium chloride for the adsorption of an anionic dye, C.I. Reactive Orange 122. The modified hectorites were characterized by XRD, SEM and BET analyses. Batch experiments were carried out for the adsorption process in terms of effect of pH, adsorbent dosage, contact time, effect of salts and different dye concentrations. Experimental results show that acidic pH favours maximum colour removal. The data are well fitted by Langmuir isotherm and the adsorption capacity for cetyldimethyl benzylammonium hectorite (CDBA-hect) and cetylpyridinium hectorite (CP-hect) have been found to be 78 and 84 mg/g respectively. Kinetic studies were fitted with the pseudo-second-order kinetic model.