Tetradecyltrimethylammonium Chloride Research Articles

Simultaneous determination of 10 quaternary ammonium salt bactericides in oral care products by high performance liquid chromatography-evaporative light-scattering detection

Quaternary ammonium salt bactericides are broad-spectrum bactericides often used in oral care products because of their high antibacterial efficacy, strong penetration, and low toxicity. However, the excessive use of quaternary ammonium salt bactericides may cause contact dermatitis, scalding poisoning, and even death. Existing methods to determine quaternary ammonium salt bactericides are unable to meet current requirements owing to the lack of determination components. Therefore, establishing a simple and accurate method for the simultaneous detection of more quaternary ammonium salt bactericides is necessary. In this study, a method that couples sample pretreatment with high performance liquid chromatography-evaporative light-scattering detection (HPLC-ELSD) was developed for the simultaneous determination of quaternary ammonium salt bactericides in oral care products, including dodecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, benzethonium chloride, tetradecyl trimethyl ammonium chloride, tetradecyldimethylbenzylammonium chloride, N-hexadecyltrimethylammonium chloride, benzyldimethylhexadecylammonium chloride, trimethylstearylammonium chloride, stearyldimethylbenzylammonium chloride, and docosyltrimethylammonium chloride. Some of these bactericides do not absorb ultraviolet light, so a universal evaporative light-scattering detector was used owing to testing cost and stability concerns. The paste samples contained thickening agents, which are highly soluble in water but insoluble in organic solvents; these agents can seriously affect the results of sample pretreatment and damage the chromatographic column. Hence, sample dehydration was necessary. In this study, four dehydration methods were compared. Anhydrous sodium sulfate (Na2SO4) was selected, and the amount of Na2SO4 was optimized. Based on the solubility of the 10 target compounds and extraction efficiency, three extraction solvents were compared, and ethanol was selected. Ultrasonic extraction was the primary extraction process used in this study. The effects of different ultrasonication times, temperatures, and powers on the extraction recoveries were also investigated. Ultimately, the optimized conditions were as follows: extraction of the dehydrated paste and powder samples using ethanol at room temperature (25 ℃) for 20 min under 100 W ultrasound power, and dilution of the liquid sample with ethanol. After extraction, the samples were separated on an Acclaim Surfactant column (150 mm×4.6 mm, 5 μm) with 50 mmol/L ammonium acetate aqueous solution (pH=5.5) (A) and acetonitrile (B) as mobile phases. The gradient elution program were as follows: 0-5.0 min, 75%A-35%A, 5.0-15.0 min, 35%A-20%A, 15.0-20.0 min, 20%A, 20.0-21.0 min, 20%A-75%A, 21.0-25.0 min, 75%A. An external standard method was used for quantitative determination. The 10 compounds were analyzed within 25 min. Linear equations, correlation coefficients, and linear ranges were obtained by analyzing a series of mixed standard working solutions. The limits of detection (LODs, S/N=3) and quantification (LOQs, S/N=10) of the 10 components were determined. Stearyldimethylbenzylammonium chloride and docosyltrimethylammonium chloride showed good linear relationships in the range of 10-200 mg/L, while the other compounds demonstrated good linear relationships in the range of 5-100 mg/L. In all cases, correlation coefficients (R2) of no less than 0.9992 were obtained. The LODs and LOQs were in the range of 1.42-3.31 mg/L and 4.25-9.94 mg/L, respectively. Ten analytes were spiked in blank matrices, such as toothpaste (paste), mouthwash (liquid), and dentifrice powder (powder) at three levels, and the recoveries and precisions were calculated. The average recoveries were 87.9%-103.1%, and the corresponding relative standard deviations (RSDs) did not exceed 5.5% (n=6). The developed method was used to detect 109 oral care products. Benzyldimethylhexadecylammonium chloride and stearyldimethylbenzylammonium chloride revealed high detection rates. Moreover, the amount of stearyldimethylbenzylammonium chloride in one toothpaste sample exceeded regulatory requirements. Given its advantages of good precision and accuracy, the developed method is suitable for the quantitative analysis of the 10 aforementioned compounds in typical oral care products. The study findings can serve as a reference for the quality and safety monitoring of oral care products.

Synergistic effects of an amphiphilic drug(propranolol hydrochloride) with cationic surfactants in an aqueous medium: A physicochemical study

The interactions of amphiphilic drug(propranolol hydrochloride, PPL) with cationic surfactants, such as dodecyltrimethylammoniumbromide(DTAB), tetradecyltrimethylammonium bromide (TTAB), trimethyltetradecylammonium chloride(TTAC) and tetyltrimethylammonium bromide(CTAB), in an aqueous medium were evaluated. The surface tension measurement was used to examine the mixed micellization behavior and surface properties of drug-surfactant mixtures. The nonideal or synergistic behaviors of the mixed systems were explored by using several physical models, such as Clint, Rubingh, Rosen, and Motomura models, based on regular solution theory and pseudophase approximation. In addition, the synergism between PPL and cationic surfactants was also confirmed using ultraviolet–visible spectroscopy. The stoichiometric ratios, binding constants, and free energy changes of the drug–surfactant mixtures were computed using Benesi–Hildebrand (B–H) theory.

Reproductive Toxicities of Tetradecyltrimethylammonium Chloride and Tetradecyltrimethylammonium Bromide on Caenorhabditis elegans over Four Consecutive Generations

Reproductive Toxicities of Tetradecyltrimethylammonium Chloride and Tetradecyltrimethylammonium Bromide on Caenorhabditis elegans over Four Consecutive Generations

Enhanced Mn2+ solidification and NH4+-N removal from electrolytic manganese metal residue via surfactants

Electrolytic manganese metal residue (EMMR) harmless treatment has always lacked a low-cost and quick processing technology. In this study, surfactants, namely tetradecyl trimethylammonium chloride (TTC), sodium dodecyl benzene sulfonate (SDBS), sodium lignin sulfonate (SLS), and octadecyl trimethylammonium chloride (OTC), were used in the solidification of Mn 2+ and removal of NH 4 + -N from EMMR. The Mn 2+ and NH 4 + -N concentrations under different reaction conditions, Mn 2+ solidification and NH 4 + -N removal mechanisms, and leaching behavior were studied. The results revealed that the surfactants could enhance the Mn 2+ solidification and NH 4 + -N removal from EMMR, and the order of enhancement was as follows: TTC ＞ SDBS ＞ OTC ＞ SLS. The NH 4 + -N and Mn 2+ concentrations were 12.3 and 0.05 mg·L -1 with the use of 60.0 mg·kg -1 TTC under optimum conditions (solid–liquid ratio of 1.5:1, EMMR to BRM mass ratio of 100:8, temperature of 20 °C, and reaction duration of 12 h), which met the integrated wastewater discharge standard (GB8978-1996). Mn 2+ was mainly solidified as Mn(OH) 2 , MnOOH and MnSiO 3 , and NH 4 + -N in EMMR was mostly removed in the form of ammonia. The results of this study could provide a new idea for cost-effective EMMR harmless treatment.

Physical properties of deep eutectic solvents based on p-toluene sulfonic acid and employment as catalyst

This work studied the physical properties of three deep eutectic solvents (DESs) and their catalytic activity in the esterification of palmitic acid and ethanol. Three types of deep eutectic solvents (DESs) were successfully prepared using p-toluene sulfonic acid monohydrate (PTSA) as hydrogen bond donor (HBD) with dodecyl trimethyl ammonium chloride (DTAC), tetradecyl trimethyl ammonium chloride (TTAC) and octadecyl trimethyl ammonium chloride (OTAC) as hydrogen bond acceptor (HBA). The freezing points of DESs were measured in the range of 50%–80% HBD mole percentage, and the composition of DTAC-PTSA, TTAC-PTSA and OTAC-PTSA at the eutectic point (the lowest freezing points) was determined respectively (DES1, DES2 and DES3). The physical properties (density, refractive index, dynamic viscosity, conductivity and pH value) of DES1∼DES3 were studied respectively in the temperature range of 298.15 K to 343.15 K. The results showed that dynamic viscosity, conductivity, density and refractive index all change approximately regularly with the increase of temperature, while pH value remains almost constant when the temperature exceeds 325 K. The catalytic ability of the three DESs in the esterification reaction of palmitic acid and ethanol was investigated, and DES2 was selected as the catalyst for subsequent experiments. The effects of temperature, acid-ethanol molar ratio, catalyst dosage and reaction time on esterification reaction were further studied, and DES’ recyclability was also tested. The results obtained showed the great potential of DES in catalytic applications.

Optimization of the demulsification of crude oil-in-water emulsions using response surface methodology

Emulsions are undesirable in the petroleum industry, as these often lead to numerous problems such as the corrosion of equipment, high-pressure drop in the pipeline, high pumping cost, and poisoning of the catalyst in upstream facilities, thus, add to the overall production cost. These emulsions are mostly encountered during enhanced oil recovery (EOR) because of the chemicals used in the process. Petroleum emulsions are commonly treated using surface-active agents known as demulsifiers. Demulsifiers can disrupt the interface between the water and the oil and separate them into individual phases. This study aims at optimizing some existing parameter conditions to obtain maximum demulsification efficiency of oil-in-water emulsions using two cationic demulsifiers namely, Cetyl-trimethylammonium bromide (CTAB), and Trimethyl-tetradecyl ammonium chloride (TTAC). The bottle test technique was used to investigate the effect of demulsifier concentration, settling time, and oil to water ratio on the demulsification efficiency. Experiments were designed using the Central Composite Design (CCD). The analysis of variance (ANOVA) was used to evaluate the significance of the experimental factors, and the factors were then optimized using response surface methodology (RSM). The results showed that all the factors studied significantly impacted the response (demulsification efficiency) and presented a p-values < 0.0001. The maximum demulsification efficiency of 82.6% and 80% were achieved at the optimum conditions of 850 ppm demulsifiers concentration within 10 h of settling time for both CTAB and TTAC emulsifiers.

Thermodynamic studies of aggregation behaviour of cationic surfactants (octyltrimethylammonium chloride/tetradecyltrimethylammonium chloride) in aqueous solutions at different temperatures

Densities for aqueous solutions of cationic surfactants, namely, octyltrimethylammonium chloride (C8TAC) and tetradecyltrimethylammonium chloride (C14TAC) in the concentration range (0.0102–0.2599) mol⋅kg−1 have been measured at (293.15, 298.15 and 303.15) K. Further, experimental density data are utilized for the calculations of apparent molar volumes of solute (Vϕ) at studied temperatures. The coefficient of thermal expansion (α) and apparent molar expansivity (Eϕ) are also obtained at 298.15 K. Application of pseudo-phase model of micellization to the Vϕ data is made for obtaining critical micelle concentration (cmc) of the studied surfactants. The magnitudes of cmc values are in the order of C8TAC > C14TAC. The change in the apparent molar volume due to aggregation (ΔVϕ,m) is found to be dependent on temperature as well on the chain length of the alkyltrimethlyammoinium ions. ΔVϕ,m slightly increases with increase in temperature and in chain length of the alkyltrimethlyammoinium ions. The standard free energy change due to micellization (ΔGm0) have also been estimated. All the results are explained on the basis of micellization of the surfactant molecules, hydrophobicity due to alkyl chain length and nature of the counter-ion.

An innovative method to enhance manganese and ammonia nitrogen leaching from electrolytic manganese residue by surfactant and anode iron plate

Electrolytic manganese residue (EMR) contains a lot of manganese (Mn2+) and ammonia nitrogen (NH4+-N), which can cause environmental pollution. In this study, surfactant and anode iron plate were used to synergistically enhance NH4+-N and Mn2+ leaching from EMR. The Characteristics of EMR, Mn2+ and NH4+-N leaching mechanism, and the leaching test were systematically studied. The results showed that the leaching efficiencies of Mn2+ and NH4+-N were 89.4% and 65.9%, respectively, when the current density was 20 mA/cm2 and iron as the anode plate, the mass of H2SO4 was 13 wt%, solid-to-liquid ratio of 1:5 at 20 °C reacting for 120 min. In addition, when the surfactant concentration of tetradecyl trimethylammonium chloride (TTC) was 100 mg/L, the leaching efficiency of Mn2+ and NH4+-N in EMR respectively increased from 89.4% to 97.1% and from 65.9% to 98.4% by adding electric field. The leaching efficiencies of Mn2+ and NH4+-N were 28.5% and 93.7%, respectively, which was higher than that attained under the same condition without an electric field and TTC surfactant. Meanwhile, electric field changed the movement and charge distribution of charged particles on the surface of SiO2 and CaSO4·2H2O particles and released soluble compound salt containing Mn2+ and NH4+-N. TTC surfactant also improved the hydrophilic and hydrophobic properties of the EMR surface and promoted the wetting ability of the particles and the leaching of Mn2+ and NH4+-N. This study shows that TTC surfactant and anode iron plate can enhance NH4+-N and Mn2+leaching from EMR.

Adsorption behaviors and mechanisms of quaternary ammonium salt collectors on quartz samples with different particle sizes

In this study, the flotation behavior of quartz samples with different particle sizes was systematically studied by conducting a microflotation experiment wherein different quaternary ammonium salt (QAS) collectors were used. The mechanism of QAS adsorption on the surfaces of the quartz samples was revealed by adsorption experiments and micro-polarity characteristics at the quartz-water interface. The microflotation experiment showed that the carbon chain length of the QAS collectors and the particle sizes of the quartz samples had a significant effect on flotation recovery. Long carbon chain collectors, tetradecyltrimethylammonium chloride (TTAC) and cetyltrimethylammonium chloride (CTAC), exhibited a better collection capability than that exhibited by short carbon chain collectors, decyltrimethylammonium chloride (103C) and dodecyltrimethylammonium chloride (DTAC). The adsorption experiments showed the adsorption amount of CTAC and DTAC on the surfaces of the quartz increased with decrease in quartz particle size. The adsorption isotherms of QAS collectors on the quartz particles were consistent with the typical “double plateau model.” The shape of the adsorption isotherm was affected by the particle sizes of the quartz and the carbon chain length of the collector. A pyrene fluorescence test showed that the maximum value of I3:I1 (I3:I1max) of the long carbon chain CTAC was larger than that of the short carbon chain DTAC. When the I3:I1 max was reached, the required concentration of CTAC was less than that of DTAC. With the increase in the DTAC concentration, the fluorescence intensity of pyrene in the supernatant initially decreased, and then increased, thereby indicating that the DTAC adsorption on the surfaces of the quartz particles gradually saturated.

Comparative Studies of Quaternary Ammonium Salts on the Aggregation and Dispersion Behavior of Kaolinite and Quartz

Fine particles in the presence of flotation reagents exhibit different dispersion and aggregation behaviors in a mineral suspension, and affect the flotation separation processes. In this study, the effects of three quaternary ammonium salts (i.e., dodecyltrimethylammonium chloride (DTAC), tetradecyltrimethylammonium chloride (TTAC), and hexadecyltrimethylammonium chloride (CTAC)) on the dispersion and aggregation behaviors of kaolinite and quartz were studied. The mechanism was systematically investigated using sedimentation tests, reagent adsorption analysis, zeta potential measurements, and SEM analysis. In the absence of reagents, the kaolinite and quartz particles exhibited good aggregation behaviors at acid and neutral pHs compared with alkaline conditions. Except for CTAC, the presence of DTAC and TTAC improved the aggregation behavior of both minerals in neutral and alkaline conditions. More, the sedimentation yields of both minerals were increased significantly with increasing the concentration of DTAC and TTAC. However, the increasing concentration of CTAC resulted in an increase in the dispersion of kaolinite and quartz particles under the same conditions. At neutral and alkaline conditions, the zeta potentials and adsorbed amounts of all three salts on the mineral surfaces were increased significantly with increasing the concentrations of salts, and the adsorbed amount adopted the following sequence: CTAC &gt; TTAC &gt; DTAC. The zeta potential results showed that the stronger adsorption of quaternary ammonium salts on mineral surfaces at neutral and alkaline conditions was mainly because of electrostatic interactions.

Effect of the alkyl chain of quaternary ammonium cationic surfactants on corrosion inhibition in hydrochloric acid solution

In this study, the effect of the alkyl chain of quaternary ammonium cationic surfactants on corrosion inhibition in hydrochloric acid (HCl) solution was investigated by using dodecyl trimethyl ammonium chloride (DTAC), tetradecyl trimethyl ammonium chloride (TTAC), cetyl trimethyl ammonium chloride (CTAC), and octadecyl trimethyl ammonium chloride (OTAC) as corrosion inhibitors to uncover their structure–efficiency relationships. The effect of the alkyl chain of quaternary ammonium cationic surfactants on corrosion inhibition in HCl solution was studied under different conditions, such as corrosion inhibitor concentration, temperature, and acidity, and this was done using the weightlessness method. The results obtained show that these inhibitors have high corrosion inhibition effect on A 3 steel, and the corrosion inhibition efficiency is dependent on the length of the alkyl chain. At the same concentration, the longer the alkyl chain, the weaker the corrosion inhibition effect. When the temperature was 50 °C and the concentration of corrosion inhibitor was 70 mg/L, the corrosion inhibition efficiency order of the four cationic surfactants was DTAC > TTAC > CTAC > OTAC. Besides, the experimental results obtained show that the adsorption of the inhibitor on the A 3 steel surface conforms to the Langmuir type isotherm, and then the corresponding adsorption thermodynamic parameters were obtained according to these parameters. It was observed that Δ H , Δ S , and E a increased with increase in the length of the alkyl chain. The adsorption of the inhibitor on the steel surface is an exothermic, spontaneous, entropy process.

Effect of the nature of counterion on the micellar properties of cationic surfactants: a conductometric study

ABSTRACTInteraction of cationic surfactants, tetradecyltrimethylammium bromide (TTAB) and tetradecyltrimethylammonium chloride (TTAC) with anionic dye, tartrazine in aqueous solution has been investigated employing conductometric technique. The free energy of transfer of hydrophobic chain, , surface contribution, and their transfer values, and , free energy, , enthalpy, , and entropy, of micellisation have been calculated. A marked decrease in the critical micelle concentration for TTAB compared to TTAC indicates dramatic role of the smaller counterion Br− over the bigger counterion Cl−. Formation of dye–surfactant ion-pairs which behave as nonionic surfactant has been proposed. Higher negative and positive values for TTAB than TTAC are attributed to difference in the size and nature of the counterions Br− and Cl−. Negative and values clearly suggest that micellisation of TTAB and TTAC is thermodynamically spontaneous and exothermic in nature. As ), it suggests that the process of micellisation is entropy dominated for the two surfactants.

Mass scale calibration of TOF‐SIMS spectra with molecular ions of internal additives

The applicability of internal additives for mass scale calibration in time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) was studied. Relation between the ions selected for mass scale calibration and the relative mass accuracy of the target molecular ions was investigated. Didecyldimethylammonium bromide (dC10DMA+Br−), dioctadecyldimethylammonium chloride (dC18DMA+Cl−) and tetradecyltrimethylammonium chloride (C14TMA+Cl−) as target molecules and octadecyltrimethylammonium chloride (C18TMA+Cl−) as an internal additive were prepared for positive TOF‐SIMS spectra. Tinuvin 770 as a target molecule and sodium hexadecyl sulfate (C16OSO3−Na+) as an internal additive were used to evaluate negative TOF‐SIMS spectra. In the case of dC10DMA+Br−, dC18DMA+Cl− and Tinuvin 770, the relative mass accuracy of the target molecular ions tends to be improved by mass scale calibration using the molecular ion of the internal additive. The relative mass accuracy of the molecular ion of the target ensured by the mass scale calibration using internal additives was less than approximately ±46 ppm. In some cases, however, internal additives highly effect on samples and change the sample properties because of coverage of the sample, removing a target molecule or causing matrix effects. It is necessary to evaluate the influence of the internal additive addition before applying internal additives. The detection of target ion peak should be especially confirmed after the addition of the internal additive. When samples are not influenced by internal additive addition, the internal additive method is effective for accurate mass calibration. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Thermal decomposition behavior and de-intercalation kinetics of kaolinite/quaternary ammonium salt complexes

Kaolinite/quaternary ammonium salt complexes were prepared by intercalation and displacement of kaolinite–N-methylformamide (Kaol–NMF) with methanol (Me) and quaternary ammonium salt. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry and differential scanning calorimetry (TG–DSC) analysis. The d-values of the kaolinite/quaternary ammonium salts complexes increase with the alkyl chain length of the quaternary ammonium salts. Based on the results and the available evidence pointing toward the interlayer structure of kaolinite intercalation complexes, the most possible structural model for the kaolinite/quaternary ammonium salt intercalation complexes was proposed. For the kaolinite–dodecyl trimethyl ammonium chloride, kaolinite–trimethyl tetradecyl ammonium chloride and kaolinite–hexadecyltrimethylammonium chloride, the intercalation molecules are oriented perpendicular to the kaolinite surface in a single layer. However, for kaolinite–stearyl trimethyl ammonium chloride, the cationic head of intercalated stearyl trimethyl ammonium chloride molecules may be partially hydrated and arrayed aslant in the interlayer space of kaolinite with an inclination angle of 35°. Thermal analysis results revealed that the thermal decomposition of kaolinite/quaternary ammonium salt complexes occurs in two main steps. The function of the most probable mechanism, activation energy E and pre-exponential factor were obtained by mutual authentication using KAS and Ozawa methods, Satava integral method and Achar–Brindley–Sharp–Wendworth methods. The average activation energy E of four kaolinite/quaternary ammonium salt intercalation complexes is 108.147, 153.478, 125.723 and 88.008 kJ mol−1, respectively. The optimized mechanism function for de-intercalation process of quaternary ammonium salt is f(α) = 1 − α and G(α) = −ln(1 − α).

Stability of trianionic curcumin enhanced by gemini alkyl O-Glucosides and alkyl trimethyl ammonium halides mixed micelles

Improved capability to inhibit degradation of trianionic curcumin has been realized in this study. The interaction between trianionic curcumin (Cur3−) and gemini dodecyl or tetradecyl O-glucoside micelles, tetradecyltrimethylammonium chloride (TTAC) or hexadecyltrimethylammonium bromide (CTAB) micelles as well as gemini alkyl O-glucosides (AGs)/alkyl trimethyl ammonium halides mixed micelles have been characterized. It is demonstrated that Cur3− cannot be incorporated into gemini AGs micelles since the lack of electrostatic attraction and degraded as rapidly as in aqueous phase. Cur3− tend to reside at palisade layer − water interface of TTAC or CTAB micelles due to the strong electrostatic interaction while moderate electrostatic interaction allows Cur3− to locate more deeply in the palisade layer of mixed micelles. Additionally, mixed micelles tend to form a more compact and hydrophobic palisade layer than pure TTAC and CTAB ones. These factors bring about enhanced fluorescence intensity and blue − shift of emission maxima, improved fluorescence anisotropy and quantum yield, as well as reduced decay rate of Cur3− in mixed micelles than in pure TTAC and CTAB ones.

A capillary liquid chromatography method for benzalkonium chloride determination as a component or contaminant in mixtures of biocides

A method for quantifying benzalkonium chloride (BAK), an alkyl dimethyl benzyl ammonium compound, in several biocides formulations is proposed. A tertiary amine like N-(3-aminopropyl)-N-dodecyl-1,3-propanediamine (TA) and a straight-chain alkyl ammonium compound like trimethyl-tetradecyl ammonium chloride (TMTDAC), have been employed as trade surfactants besides BAK. Two capillary analytical columns with different polarities are tested: inertsil CN-3 capillary column (150mm×0.5mm i.d., 3μm particle diameter) and a non endcapped Zorbax C18 capillary column (35mm×0.5mm i.d., 5μm particle diameter). This latter column provided the best separation of the BAK homologues in less than 12min using acetonitrile:acetate buffer (50mM, pH 5) 85:15 at 20μLmin−1. The proposed method combines on-line in-tube solid-phase microextraction (IT-SPME) coupled to capillary liquid chromatography (CapLC) and UV diode array detection. Matrix effect was present when TA were in excess to BAK. If TMTDAC is the co-biocide, matrix effect is always present. A decreasing of analytical response mainly for C12-BAK homologue was found using both chromatographic columns. The charged amount of mixture in the system was the most important parameter for obtaining reliable results. 1mL was the on line processed sample volume optimum for concentrations lower than 35μgmL−1 of total surfactants. LODs were 0.03μgmL−1 and 0.006μgmL−1 for C12-BAK and C14-BAK, respectively. This method is also of use to evaluate the unwanted presence of BAK in biocide formulations due to industrial processes.

Hydrophobic aggregation of fine particles in high muddied coal slurry water.

The hydrophobic aggregation of fine particles in high muddied coal slurry water in the presence of four quaternary ammonium salts of 1231(dodecyl trimethyl ammonium chloride), 1431(tetradecyl trimethyl ammonium chloride), 1631(cetyl trimethyl ammonium chloride) and 1831(octadecyl trimethyl ammonium chloride) was investigated through the measurement of contact angles, zeta potentials, aggregation observation, adsorption and sedimentation. The results show that quaternary ammonium salts can enhance the hydrophobicity and reduce the electronegativity of particle surface, and thus induce a strong hydrophobic aggregation of slurry fine particles which promotes the settlement of coal slurry water. The adsorption of quaternary ammonium salts on slurry particles increases with the increase of alkyl chain length and reagent dosage, and will reach equilibrium when the dosage reaches a certain value. Weak alkaline conditions also can promote quaternary ammonium salts to be adsorbed on the coal slurry fine particles. In addition, reasonable energy input and a chemical environment of weak alkaline solution are conducive to hydrophobic aggregation settlement of high muddied coal slurry water with quaternary ammonium salts. The main mechanism of hydrophobic aggregation of coal slurry particles with quaternary ammonium salts is 'adsorption charge neutralization' and hydrophobic interaction.

Facile preparation of SiO2 hybrid nanoparticles via Cu2+-amine redox-initiated radical polymerization

The CuSO4-catalyzed surface-initiated conventional radical graft polymerization of electron-deficient monomers such as N,N-dimethylacryamide (DMAAm) was carried out from amino-functionalized SiO2 nanoparticles (SiO2–NH2) to directly prepare hybrid SiO2 nanoparticles (SiNPs) chemically grafted with functional poly(N,N-dimethylacryamide) (SiO2-g-PDMAAm) in aqueous media with trimethyltetradecylammonium chloride (TTAC) added as a surfactant. The optimum reaction conditions were as follows: weight feed ratio CuSO4·5H2O:DMAAm:H2O:SiO2–NH2:TTAC of 1:500:5,000:1,000:100 and reaction temperature at 80 °C. Spectroscopy and microscopy confirmed the successful graft polymerization and the formation of hybrid SiNPs with PDMAAm chains. Thermogravimetric analysis indicated the grafting yield could be up to 15.39 wt%. As the active radicals only formed on the SiNP surfaces, there was no free polymer in the reacting mixture. Because of the presence of PDMMAm chains, the hybrid SiO2-g-PDMAAm nanoparticles exhibited an enhanced dispersion stability in aqueous media over the pristine SiO2–NH2, and a thermoresponsive settlement behavior. The parallel experiments with other electron-deficient monomers suggest that the current strategy requires less post-treatment, mild conditions and affords universal applicability.

Mass‐scale calibration of TOF‐SIMS spectra using quaternary ammonium ions

A novel method with quaternary ammonium salts as internal additives has been applied to the mass‐scale calibration of time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS). Five kinds of quaternary ammonium salts, octyltrimethylammonium bromide (C8TMA), tetradecyltrimethylammonium chloride (C14TMA), octadecyltrimethylammonium chloride (C18TMA), cetylpyridinium chloride (CPC) and benzyldimethyltetradecylammonium chloride (Bzl) were diluted with NH3 aqueous solution and were mixed in equal quantities. The mixed solution was covered on a Si wafer and was measured by TOF‐SIMS. When molecular ions of C8TMA, C14TMA, and C18TMA were used for the mass‐scale calibration, the relative mass accuracy of low‐mass CXHY fragment ions indicated negative values and depended on the carbon chain length and the degree of unsaturation. This result means that the conventional mass‐scale calibration with frequently employed low‐mass CXHY fragment ions leads to degradation of the mass accuracy of high‐mass molecular ions. To improve the mass accuracy of molecular ions of CPC and Bzl, ions should be selected for the mass‐scale calibration in the following two ways: One way is for ions to consist only of molecular ions of C8TMA, C14TMA, and C18TMA, and the other way is for ions to include one of the molecular ions: C8TMA, C14TMA, and C18TMA, along with the CXHY fragment ions. This novel mass‐scale calibration method is promising for realizing the correct identification of unknown high‐mass molecular ions. Those quaternary ammonium salts are powerful candidates of internal additives. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Zeta potential of limestone in a large range of salinity

Experimental investigations have been conducted to elucidate the variation of the zeta potential (ζ) of limestone in a large range of salinity. The effects of the type and concentration of inorganic salts, the pH, and the adsorption of the oil polar fractions, naphthenic acid and cationic surfactant on the ζ have been investigated in the paper. The results show that the ζ rises toward the positive with the increase of the concentration of inorganic salt, but the increase rate gets very low in the high-concentration brine. The mineral composition of the limestone has also some influence on the ζ. The high pH value results in the large ζ, and the adsorption of oil polar fractions and naphthenic acid is beneficial to the increase of the ζ. However, increasing the salinity reduces the effect of the pH, oil polar fractions and naphthenic acid on the ζ, and the ζ is nearly not affected by the above influencing factor in the formation water (total salinity: 223,802.8mg/L). Among the three surfactants of dodecyl trimethyl ammonium chloride, tetradecyl trimethyl ammonium chloride and octadecyl trimethyl ammonium chloride, the adsorption of octadecyl trimethyl ammonium chloride onto the rock surface is more efficient to increase the ζ, and the more adsorption leads to the higher ζ in the surfactant solutions with the same salinity. The adsorption quantity of octadecyl trimethyl ammonium chloride onto the limestone is the largest when the surfactant concentration is the same, and the high salinity promotes the adsorption of the surfactant onto the limestone. Nevertheless, the ζ decreases rather than rising due to the simultaneous increase of the salinity and surfactant adsorption. The above results indicate that the salinity is the dominant influencing factor on the ζ of the limestone in various conditions, which can be used as theoretical guidance for improved oil recovery in the carbonate reservoir with different salt contents.