Ethylhexadecyldimethyl Ammonium Research Articles

Removal of Cd(II) and Hg(II) from effluents by ionic solid impregnated chitosan

Ethylhexadecyldimethyl ammonium bromide impregnated chitosan (EHDAIC) was prepared to remove cadmium and mercury from synthetic effluent. The adsorbent was characterized by FTIR, XRD, SEM, EDX and TGA-DTA. Adsorption studies were carried out under different conditions of pH, adsorbent dose, temperature, and contact time. The results showed that the adsorption capacity of EHDAIC is a function of the solution pH and the optimum pH for these metal ions was found to be 3.0. The equilibrium data has been described using Langmuir and Freundlich isotherm models. The maximum adsorption capacity of 341.30mg/g was observed for Cd(II) and 43.43mg/g for Hg(II) in accordance with Langmuir adsorption isotherm in the form of their chloro complexes. The kinetic data fitted well with pseudo-second-order model, and equilibrium data was found to follow Freundlich isotherm model. The calculated thermodynamic parameters showed that the adsorption process was feasible, exothermic and spontaneous. Effect of common excipient ions was studied. Also the material was tested for large sample volumes using column extraction process. The adsorbent material could be regenerated for repetitive applications.

Investigation on interaction of DNA and several cationic surfactants with different head groups by spectroscopy, gel electrophoresis and viscosity technologies

In this study, the interaction between DNA and several cationic surfactants with different head groups such as ethyl hexadecyl dimethyl ammonium bromide (EHDAB), hexadecyl dimethyl benzyl ammonium chloride (HDBAC), and cetyl pyridinium bromide (CPB) were investigated by UV–vis absorption, fluorescence and circular dichroism (CD) spectroscopy, gel electrophoresis, and viscosity technologies. The results show that these cationic surfactants can interact with DNA and major binding modes are electrostatic and hydrophobic. Also, CPB and HDBAC molecules interact with DNA by partial intercalation, and CPB has slightly stronger intercalation than HDBAC, while EHDAB interacts with DNA by non-intercalation. The different head groups of the surfactant molecules can influence the interaction strength. CPB has the stronger interaction with DNA than the others. Moreover, surfactant concentration, the ratio of DNA and fluorescence probe, ionic strength can influence the interaction. The surfactants may interact with DNA by the competition reactions with BR for DNA-BR. The increase of ionic strength may favor the surface binding between DNA and surfactants to some extent. This work provides deep mechanistic insight on the toxicity of cationic surfactants with different head groups to DNA molecules.

Application of micellar enhanced ultrafiltration for the removal of sunset yellow dye from aqueous media

ABSTRACTIn this article, we report the removal of a reactive dye, viz. sunset yellow, from the aqueous solution using micellar media of two cationic surfactants, viz. cetyltrimethylammonium bromide and ethyl hexadecyldimethyl ammonium bromide (. The values of rejection coefficient (R%) and permeate flux (J) have been calculated using membranes with different pore sizes, viz. 10,000 (10k) molecular weight cutoff (MWCO) and 30,000 (30k) MWCO at 1.5 bar transmembrane pressure. The membrane of 30k MWCO was found to be more suitable in order to retain the dye molecules incorporated in the micelles.

Physicochemical investigation of sulfonamide-derived compounds interacting with conventional cationic surfactants in aqueous media

ABSTRACTThe sulfonamide core in compounds is effective synthons, which offer exciting perspectives in chemotherapeutic and pharmacological research. In this study, we investigated the molecular interaction of potent sulfonamide derivatives (SDs), 2-benzenesulfonamido-3-methylbutyric acid (BSB) and tetraaquabis{3-methyl-2-[(phenylsulfonyl)amino]butanoate}copper(II) (Cu-BSB), with cationic surfactants, cetyltrimethyl ammonium bromide (CTAB) and ethylhexadecyl dimethyl ammonium bromide (EHDAB), using UV-visible spectroscopy and steady-state fluorescence measurements. Various mathematical models were applied to quantify the effect of cationic surfactants on physicochemical characteristics of BSB and Cu-BSB. These interactions were confirmed by estimating the partition coefficient (Kx), binding capacities (Kb), Stern-Volmer quenching constant (Ksv), and related Gibbs free energies (ΔGb). The in-depth mechanism revealed that the binding mode in SD–surfactants combinational system is spontaneous and quenching exists in static mode initiated by ground-state complex formation. We believe that the true knowledge of host–guest interaction mechanisms concerning model membrane with entrapped moiety can help in better understanding of molecular recognition in related phospholipid membrane models.

Experimental study of nanoparticle-surfactant-stabilized CO2 foam: Stability and mobility control

CO2 injection has proved to be the most common and efficient enhanced oil recovery techniques which leads to more residual oil recovery. Unfavorable sweep efficiency which results in fingering propagation and causes early gas breakthrough is the most challenging issue of gas flooding process. The aim of this work is to study foam stability and analyze the mobility of CO2 foam stabilized by mixture of raw silica nanoparticles and ethyl hexadecyl dimethyl ammonium bromide (cationic surfactant). The result is obtained through both dynamic and static techniques using a new adsorption index.NPS-stabilized foams are generated using Ross-Miles method. A novel index for the adsorption of surfactant molecules on the nanoparticles is proposed using electrical conductivity measurement. Analyzing the foam decay behavior based on this adsorption index, it is found that the foam life can be divided into two general regions. First, low adsorption region that the foam stability is initially dominated by surfactant concentration and after a while it is controlled by nanoparticles. Second, high adsorption region, that the foam stability, is mostly affected by both nanoparticles and surfactant concentrations as well.The pressure behavior and morphology of the foam are investigated using dynamic characterization apparatus. By using a capillary viscometer in this apparatus, foam apparent viscosity is measured for different phase ratios, and nanoparticle and surfactant concentrations. It is observed that NPS solutions produce uniformly smaller foams with higher apparent viscosity compared to those with surfactant solutions. The results reveal that in different surfactant concentrations, the apparent viscosity of NPS-stabilized foam experiences a maximum value of 6.03cp which is about 9 times larger than that of CO2/water dispersion flood. This maximum is coincided with the maximum adsorption index and the maximum hydrophobicity.

Removal of malachite green dye from aqueous solutions using organically modified hydroxyapatite

The removal of malachite green dye (MG) from aqueous solution was studied using organically modified hydroxyapatite. Hydroxyapatite (HAP) was organically modified with different concentrations of the organic surfactant ethylhexadecyldimethyl ammonium bromide (EHDAB). The modified apatite was characterized using FTIR, XRD and SEM. The modified apatite was studied for removal of MG from aqueous solution and the experimental parameters were studied. The effect of contact time, adsorbent dose, dye concentration and temperature was studied. The equilibrium uptake was increased with increasing the initial dye concentration in solution. The experimental isotherm data were analyzed using Langmuir adsorption isotherm model. The adsorbed amount of MG onto the modified apatite was found to increase with increasing the adsorbent concentration. The maximum monolayer adsorption capacity was found to be 188.18mg/g at 30°C.

Application of Micellar-Enhanced Ultrafiltration for the Removal of Reactive Blue 19 from Aqueous Media

The present study reports the surfactant-based separation of a reactive dye (reactive blue 19 (RB-19), from aqueous solution containing two cationic surfactants (cetyltrimethylammonium bromide (CTAB) and ethyl hexadecyldimethyl ammonium bromide (EHAB)). Three membranes of different pore size (5000, 10,000, and 30,000 molecular weight cutoff (MWCO)) were used for the determination of rejection coefficient and permeate flux of the solution at 1.5 bar transmembrane pressure (TMP). The membrane of 10,000 MWCO was found to be the most suitable in regard to retaining the dye molecules incorporated in the micelles.

Characterisation of montmorillonites simultaneously modified with an organic dye and an ammonium salt at different dye/salt ratios. Properties of these modified montmorillonites EVA nanocomposites

In this work, a sodium montmorillonite (Na+-Mt) was modified with two molecules simultaneously, an organic dye, methylene blue (MB), and ethyl hexadecyl dimethyl ammonium (EHDDMA). The synthesised organo-montmorillonites (OMt) combining different proportions of the two molecules were thoroughly characterised and mixed with ethylene vinyl acetate copolymer (EVA) in order to check the ability of these OMt as pigments and reinforcing additives. The synthesised OMt combining both surfactants, MB and EHDDMA, present higher interlayer distances than those with only MB, which were employed in previous works as nanopigments. When these OMt were incorporated in the EVA matrix, the obtained clay polymer nanocomposites (CPN) showed a high exfoliation degree of the OMt in the polymer, in such a way that at 80% of the cationic exchange capacity (CEC) of the Mt exchanged with EHDDMA, most of the OMt was exfoliated. Moreover, all the obtained CPN showed an increase in the Young's Moduli compared to the EVA reference, and especially those containing higher amounts of MB. The thermal stability of the CPN also increases with the MB content, compared to other CPN including conventional surfactants. The hiding power and colouring power achieved in the CPN are higher even with a much lower load of MB when EHDDMA is exchanged in the Mt.

Effect of molecular structures of Gemini and polymerizable emulsifiers on cationic emulsion copolymerization of styrene and butyl acrylate

In order to understand the effect of molecular structures of emulsifiers on the cationic emulsion copolymerization of styrene (St) and butyl acrylate (BA) in details, hexadecyl trimethyl ammonium bromide (CTAB), methacryloxy ethyl hexadecyl dimethyl ammonium bromide (DMHB), ethanediyl bis(hexadecyl dimethyl ammonium bromide) (G16-2-16), and maleic acid diethyl bis(hexadecyl dimethyl ammonium bromide) (P16-8-16) were used as emulsifiers. TEM photos, instantaneous conversions, and colloidal features, such as the particle size, surface charge density, and glass transition temperature (Tg), were measured. Compared with polymerizable emulsifiers (DMHB and P16-8-16), non-polymerizable emulsifiers (CTAB and G16-2-16) produced more uniform nanospheres. In the reactions with polymerizable emulsifiers, higher reaction rates, lower surface charge densities, and lower Tg were observed. Compared with the single-chain emulsifiers, the double-chain emulsifiers resulted in lower reaction rates, bigger particle sizes, better monodispersities, and higher surface charge densities.

The influence of surfactant loading level in a montmorillonite on the thermal, mechanical and rheological properties of EVA nanocomposites

In this work, montmorillonite (Mt) has been organically modified with ethyl hexadecyl dimethyl ammonium (EHDDMA) in 20, 50, 80 and 100% of the nominal exchange capacity (CEC) of the Mt. A full characterization of the organo-montmorillonite (OMt) obtained has been made, including thermal analysis, X-Ray Diffraction, elemental analysis CHN and nitrogen adsorption. According to the results, 12% in mass of the surfactant added is strongly retained by the Mt. When the mass percentage of EHDDMA exchanged in the OMt is increased up to this level, the interactions OMt–EHDDMA are steeply reduced depending on the EHDDMA content.Clay polymer nanocomposites (CPN) were prepared by melt mixing of EVA and different loads of OMt. The CPN were compress molded to obtain 1mm thick sheets, which have been characterized according to their mechanical, thermal and rheological behaviors. The major changes in the structure of the OMt are obtained for low contents of EHDDMA. Nevertheless, the CPN containing OMt exchanged at 20 and 50% of the CEC show relatively low effect of the EHDDMA while the mechanical response and rheological behavior of CPN with OMt modified at 80 and 100% of the CEC are much more pronounced.

Ordered gold nanoparticle arrays as surface-enhanced Raman spectroscopy substrates for label-free detection of nitroexplosives

Nitroexplosives, such as 2,4,6-trinitrotoluene (TNT) which is a leading example of nitroaromatic explosives, are causing wide concern. Motivated by the urgent demand for trace analysis of explosives, novel surface-enhanced Raman spectroscopy substrates based upon highly ordered Au nanoparticles have been fabricated by a simple droplet evaporation method. It is noteworthy that an ethylhexadecyldimethyl ammonium bromide bilayer surrounding each individual nanoparticle not only is responsible for these periodic gap structures, but also tends to promote the adsorption of TNT on the composite NPs, thus resulting in a considerable increase of Raman signal. These desirable features endow the resulting SERS substrates with excellent enhancement ability and allow for a label-free detection of common plastic explosive materials even with a concentration as low as 10 −9 M.

Study on Associative Polymerizable Inverse Microemulsion

In an effort to determine the suitable polymerizable inverse microemulsion region in pseudoternary phase diagram (PPD), the pseudoternary system of Span80‐Tween80/isopar M/aqueous solution of acrylamide and 2‐(methacryloyloxyl) ethyl hexadecyl dimethyl ammonium bromide (DM16) was investigated at 40°C. The PPD was obtained by a combination method of turbidimetry and conductivity (CMTC). The reliability of the PPD line was checked by investigating the state of selected experimental points near the boundary line using the Pulsed Near Infrared Light Scattering (PNILS) and centrifugation. Based on the achieved PPD, a series of hydrophobically associating polyacrylamide (HAPAM) microlatex were successfully prepared by choosing the right formulation. It shows that CMTC could be used as a good method in ascertaining a polymerizable inverse microemulsion region, from which optimized HAPAM can be prepared. The factors governing the area of the polymerizable inverse microemulsion region were also discussed.

Anionic sorption onto modified natural zeolites using chemical activation

The sorption of arsenate on modified-natural zeolites was investigated at varying chemical pretreatment. Zeolites were used extensively for water softening, however, a few arsenic studies have been conducted with zeolites. Arsenic pollution of the environment has received renewed attention due to toxicological evidence of its potential health hazards to humans. The ability of modified natural zeolites (stilbite and laumontite) to remove inorganic anion was investigated. The zeolites used in this work are stilbite-laumontite from Zeolitic Zone of the Corda Formation. Experiments were conducted to evaluate the relationships of the arsenate in the modified natural zeolites. Laboratory experiments were conducted examining the effect of the sorption of cationic surfactants and coagulant on stilbite-laumontite mixtures and on the subsequent sorption of arsenate by modified zeolites. Removal of arsenate using hexadecyltrimethylammonium (HDTMA)-modified zeolites was satisfactory whereas ethylhexadecyldimethylammonium (EHDDMA) and ALUM-modified zeolites were not removed with the same efficiency.

Thermal properties and adhesiveness of soy protein modified with cationic detergent

AbstractThis research studied the effects of cationic detergents on the adhesiveness and thermal properties of soy protein isolate (SPI). Three cationic detergents, hexadecyltrimethyl ammonium bromide, ethylhexadecyldimethyl ammonium bromide (EDAB), and benzyldimethylhexadecyl ammonium chloride, each at concentrations of 1.3, 2.6, 5.2, and 7.8 mM, were used to modify SPI. The effect of pH at selected EDAB concentrations was also studied. Results showed that both detergent concentration and pH had significant effects on the adhesiveness of modified SPI. SPI modified with detergent at a concentration of 2.6 mM yielded the greatest dry tensile strength and water resistance, which indicated that a moderate protein denaturation might be favorable to the adhesion of SPI. Both modified and unmodified SPI showed greater adhesive strength at their optimal pH values. Modified SPI showed greatest adhesive strength at pH 7, whereas unmodified SPI showed greatest adhesive strength at pH 4.5; the tensile strength of modified SPI was greater than that of unmodified SPI. The protein‐denaturation temperature and the enthalpy of modified SPI adhesives were also analyzed by using DSC. Denaturation of the native structure of SPI increased as detergent concentration increased.

Organic cation effects on the sorption of metals and neutral organic compounds on aquifer material

Abstract Sorption of ethylhexadecyldimethyl ammonium (EHDDMA+), a large organic cation, and three neutral organic compounds (NOC's) on two low organic carbon aquifer materials was studied using a soil batch equilibration technique. EHDDMA+ competed effectively with metals for exchange sites and EHDDMA+ sorption was accompanied by an equimolar charge desorption of metals. NOC's sorption on the aquifer materials was low (K ≤ 0.22) which was consistent with the sorbent's low organic carbon content. However, EHDDMA+ sorption increased toluene sorption by two orders of magnitude. The enhanced toluene sorption was. due to the hydrophobic surface provided by the hydrocarbon moiety of sorbed EHDDMA+.

Prediction of Equilibria and Mass Transfer Rates in Continuous Foam Fractionation of Phosphate

Abstract An experimental investigation of the effect of the operating variables on the removal of phosphate in continuous foam fractionation using ethylhexadecyl dimethylammonium bromide as surfactant was performed. The removal of phosphate is described in terms of surface concentration of phosphage, and the operating variables are bubble residence time, concentration of phosphate, and pH of the bulk solution. Experimental equilibrium residence times agree well with those calculated from the Poisson equation of surface potential. The preferential adsorption ratio of divalent to monovalent phosphate is derived from the Gibbs equation, and is found to be six, based on a statistical correlation using the Langmuir adsorption isotherm.

Batch and continuous ion‐flotation of hexavalent chromium

AbstractAn experimental investigation is presented of the flotation of dichromate ion using a cationic surfactant, ethylhexadecyldimethylammonium (EHDA) bromide. Dichromate ion forms a colloidal complex with EHDA ion in a molar ratio of 1 : 2, which may be efficiently floated from solution and concentrated in a stable foam produced by excess surfactant. Batch experiments with feed solutions containing 5–100 mg/l of dichromate ion produced residual dichromate concentrations ranging from 0.004 to 0.198 of that of the feed, depending upon the concentration of surfactant in the feed. The effects of pH and of possible interfering anions were determined. Continuous experiments indicated the reduction of dichromate from 50 to 15 mg/l, producing a foam stream containing 450 mg/l of dichromate. The influence of retention time is discussed.