Synthesis,Surface and Antimicrobial Activities of Novel Cationic Gemini Surfactants

A series of novel cationic gemini surfactants [C_nH_2n+1–O–CH₂–CH(OH)–CH₂–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? [ 3a (n = 12), 3b (n = 14) and 3c (n = 16)] having a 2‐hydroxy‐1,3‐oxypropylene group [?CH₂–CH(OH)–CH₂–O–] in the hydrophobic chain have been synthesized and characterized. Their water solubility, surface activity, foaming properties, and antibacterial activity have been examined. The critical micelle concentration (CMC) values of the novel cationic gemini surfactants are one to two orders of magnitude smaller than those of the corresponding monomeric surfactants. Furthermore, the novel cationic gemini surfactants have better water solubility and surface activity than the comparable [C_nH_2n+1–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? (n‐4‐n) geminis. The novel cationic gemini surfactants 3a and 3b also exhibit good foaming properties and show good antibacterial and antifungal activities.     

Foam inhibition in an aqueous sodium dodecylbenzene sulfonate solution by poly(dimethylaminoethyl methacrylate)

The mechanism of foam inhibition in an aqueous sodium dodecylbenzene sulfonate (DBSNa) solution by temperature-sensitive, water-soluble poly(dimethylaminoethyl methacrylate) (PDM) was investigated. The solution's foam collapsing rate, % transmittance, surface tension, pH, temperature, and degree of hydrophobicity of PDM showed that aging a PDM–DBS solution 125 to 280 hr produced a turbid solution and effectively inhibited foaming. Likewise, controlling the pH at 4 ≤ pH ≤ 7 and increasing the hydrophobicity of PDM enhanced the foam-inhibiting action of the polymer. The reaction between DBSNa and PDM was temperature dependent and the temperature effect was almost reversible. When compared with other available commercial antifoaming agents, PDM was found most effective in suppressing foam formation in aqueous DBSNa solution.     

Synthesis,Physico-Chemical Properties and Enhanced Oil Recovery Flooding Evaluation of Novel Zwitterionic Gemini Surfactants

In this work, a novel series of zwitterionic gemini surfactants with different hydrophobic tails were synthesized and characterized. The physico‐chemical properties of these products (such as surface tension, oil/water interfacial tension, foaming ability, and the wetting ability of paraffin‐coated sandstone) were fully studied. The CMC of the synthesized surfactants ranged from 2.17 × 10^?4 mol L^?1 to 5.36 × 10^?4 mol L^?1 and corresponding surface tension (γ_CMC) ranged from 26.49 mN m^?1 to 29.06 mN m^?1, which showed excellent efficiency among the comparison surfactants. All the products can reduce the interfacial tension to a relatively low level of about 0.1–1.0 mN m^?1. Additionally, results from applying different hydrocarbons suggested that the synergy will be clearer and oil/water interfacial tension will be lower if the oil components are similar to the surfactants. Contact angle and foaming measurements indicated that the surfactants exhibited good wetting and foaming abilities. The results of oil flooding experiments using an authentic sandstone microscopic model showed that C‐12 and CA‐12 could effectively improve the displacement efficiency by 21–29 %.     

Solution Properties of Alkyl β-D-Maltosides

Alkyl β-D-maltosides are an important class of sugar-based nonionic surfactants and have been widely studied. Nevertheless, it is still necessary to investigate further their amphiphilic structure-surface property relationships. In this article, we reported a series of properties of synthetic alkyl β-D-maltosides ( 6a – 6i , n = 6–18) including their hydrophilic–lipophilic balance (HLB) number, water solubility, hygroscopicity, moisture-retention capacity, foaming ability, surface tension, thermotropic phase behavior, and skin irritation. Their HLB number and water solubility decreased with increasing alkyl chain length. Hexyl β-D-maltoside exhibited the strongest hygroscopicity and moisture-retention capacity. Decyl β-D-maltoside and dodecyl β-D-maltoside possessed excellent foaming power and foaming stability. Furthermore, the critical micelle concentration (CMC) of alkyl β-D-maltoside ( 6a – 6g , n = 6–14) and their surface tension at CMC decreased with increasing alkyl chain length. At last, alkyl β-D-maltosides ( 6a – 6g ) should be considered as safe surfactants by the skin irritation assessment.     

Foam separation of colloidal particulates

The foam-separation process may be utilised for the separation of hydrophobic (and hydrophilic) colloidal particulates of a flocculent nature from aqueous suspension by the addition of a surfactant with opposite charge and by gas dispersion through the suspension. Process operation and the significant independent and dependent variables are discussed. A model is presented that divides the process into a basic separation step in which the oleophilic particles are adsorbed at the gas/suspension interfaces of the bubbles and an entrainment step in which bulk solution is physically carried into the foam. The model is used to interpret experimental results for the ferric oxide-dodecyl sodium sulphate system, from consideration of residual ferric oxide concentrations, foam volumes, and removal ratios. A parameter, relative fractionation, is used to compare quantities of surfactant and particulates in the foam and in the bulk solution. Results are used to contrast the effects of surfactants on the foam separation of various particulates of opposite charge, including Escherichia coli, stannic oxide and kaolin clay, with particular emphasis on effects on foaming ability.     

Study of Foaming Properties and Effect of the Isomeric Distribution of Some Anionic Surfactants

Using different reaction conditions of photosulfochlorination of n-dodecane, two samples of anionic surfactants of sulfonate type are obtained. Their micellar behavior has been already reported and the relationship between their isomeric distribution and their chemical structures and micellar behaviors have been more thoroughly explored. In this investigation, we screened the foaming properties (foaming power and foam stability) by a standardized method very similar to the Ross–Miles foaming tests to identify which surfactants are suitable for applications requiring high foaming, or, alternatively, low foaming. The results obtained for the synthesized surfactants are compared to those obtained for an industrial sample of secondary alkanesulfonate (Hostapur 60) and to those of a commercial sample of sodium dodecylsulfate used as reference for anionic surfactants. The foam formation and foam stability of aqueous solutions of the two samples of dodecanesulfonate are compared as a function of their isomeric distribution. These compounds show good foaming power characterized in most cases by metastable or dry foams. The highest foaming power is obtained for the sample rich in primary isomers which also produces foam with a relatively high stability. For the sample rich in secondary isomers we observe under fixed conditions a comparable initial foam height but the foam stability turns out to be low. This property is interesting for applications requiring low foaming properties such as dishwashing liquid for machines. The best results are observed near and above the critical micellar concentrations and at 25 °C for both the samples.

Preparation and properties of water‐soluble polyester surfactants. I. Preparation and surface activity of poly(ethylene glycol)‐dimethyl 5‐sulfo‐isophthalate sodium salt polyester surfactants

The reaction of poly(ethylene glycol) (PEG, number‐average molecular weight M_n = 400‐2000) and dimethyl 5‐sulfoisophthalate sodium salt (SIPM) synthesized a series of anionic polymeric surfactants having a range of molecular weights. ¹H‐NMR, FTIR, and elemental analysis were employed to characterize the structures of these compounds. Also, the influences of the PEG segment lengths of PEG/SIPM copolymers on the surface tension, foaming properties, wetting power, and dispersant properties were investigated. The experimental results indicated that the solution that contained the PEG/SIPM copolymer surfactants exhibited excellent surface‐active properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2727–2731, 2002     

Synthesis and Properties of pH-Dependent Gemini Surfactants Containing Multiple Carboxyl Groups

A series of Gemini surfactants N,N″-dialkyl-N,N′,N″-tripropionate diethylenetriamine (referred as DTPDT-n, where n is the length of the hydrocarbon chain, n = 10, 12, 14) were synthesized, which have three carboxylic head-groups and two hydrophobic alkane chains. The products were characterized by means of nuclear magnetic resonance and mass spectrometry. The physicochemical properties of DTPDT-n surfactants with different hydrocarbon chain lengths were studied such as isoelectric point, surface activities, emulsifying properties, and foam properties. It is showed that these compounds exhibit pH-dependent protonation-deprotonation behavior. The isoelectric points of DTPDT-n surfactants are between 3.40 and 10.90. The critical micellar concentration (cmc) of all three surfactants are lower than the corresponding monomeric surfactants (single head group, single-chain), especially DTPDT-14, whose cmc can reach 2.29 × 10⁻⁵ mol/L. With an increase in the length of the alkyl chain, the solubility of the surfactants decreases and the surface tension of the three surfactants at cmc increases. In consideration of pH, all of three surfactants appear better emulsifying capacity and foaming property under weak alkaline conditions. DTPDT-14 has the best performance of emulsifying capacity among the three surfactants. DTPDT-10 has excellent foaming ability and foam stability.     

Synthesis and Properties of Two Amino Carboxylic Acid Gemini Surfactants

The number of hydrophilic and hydrophobic groups of a surfactant has a great influence on its property. Two Gemini surfactants, N,N″‘-didodecyl-N,N',N″,N″‘-tetrapropionate triethylenetetramine and N,N'-didodecyl-N,N'-dipropionate ethylenediamine (referred as DTPTT and DDPED), were prepared by Michael addition reaction of the didodecyl secondary amines with methyl acrylate. The didodecyl secondary amines were synthesized by nucleophilic substitution reaction of triethylenetetramine or ethylenediamine with bromododecane. The DTPTT and DDPED surfactants were characterized by mass spectrometry and proton nuclear magnetic resonance spectrometry. The surface activities of the DTPTT and DDPED aqueous solutions were studied by surface tension measurements. The surface tension and critical micelle concentration (cmc) of DDPED is smaller than that of DTPTT. The DDPED can reduce the surface tension of water to approximate 34 mN m⁻¹ at concentration levels of 10⁻⁵ mol L⁻¹. The aggregation behavior of the DTPTT and DDPED aqueous solution were studied by dynamic light scattering and transmission electron microscopy. Both surfactants can form spherical vesicles at a solution of about 3–5 times cmc of the Gemini surfactants. The foam property was determined by nitrogen blowing method. The DTPTT has relatively good foaming ability and DDPED has excellent foam stability. The foam volume of DDPED barely change within 1000s. The emulsion stability of the Gemini surfactants was determined by separation time of water from the emulsion. The emulsion stability of DDPED is equivalent to Tween 80. The DDPED Gemini surfactant with two hydrophilic carboxylic groups has better surface activity, foam stability, and can be used as an O/W emulsifier.     

Synthesis and Properties of Quaternary Ammonium Gemini Surfactants with Hydroxyethyl at Head Groups

A series of cationic gemini surfactants C_mH_{2m + 1}N⁺(CH₂CH₂OH)₂ (CH₂)_s N⁺(CH₂CH₂OH)₂C_mH_{2m + 1} 2Br⁻, referred to as m-s-m (OH) (m = 8,10,12, s = 3,4), were prepared by quaternization of dihydroxyethyl tertiary amines with dibromoalkane. The dihydroxyethyl tertiary amines were synthesized by nucleophilic substitution of diethanolamine with bromoalkane. The characterization of the m-s-m (OH) surfactants was performed using ¹H NMR and MS. The surface activities and aggregation behavior in aqueous solution of the m-s-m (OH) surfactants were studied using surface tension measurements, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The surface tension and critical micellar concentration of these surfactants in aqueous solution decreased dramatically due to the introduction of hydroxyethyl at the head group. The micelles and/or vesicles formed in the aqueous solution of m-s-m (OH) surfactants were strongly dependent upon the lengths of spacer chains and carbon chains. The number of vesicles increases and that of micelles decreases when the lengths of spacer chains and carbon chains increase.     

Foaming Properties of Commercial Lauramide Amide Oxide in High‐Salinity Water

The original purpose of our work was finding commercial foaming agents for high‐salinity reservoirs. During the study, the commercial lauramide amide oxide solution displayed different foaming properties in high‐salinity water (salinity 220,000 mg/L) at different aging times and relatively low temperature (25 °C). Foam volume decreases drastically first with the increase of aging time. Then, with further aging, foam volume increases. However, in low‐salinity water or at high temperature, no obvious foam volume variation was observed. Lauric acid in the commercial surfactant plays a key role. Under proper temperature and pH conditions, lauric acid will react with Ca²⁺. Calcium laurate generated from lauric acid in the commercial form and Ca²⁺ from water influences the foaming property significantly. At the beginning of calcium laurate generation, surfactants adsorb on calcium laurate and decelerate the diffusion velocity of lauramide amide oxide from the bulk phase to the air–water interface. With the increase of aging time, calcium laurate gathers, thus adsorption of lauramide amide oxide by calcium laurate decreases. Hence, the foaming volume increases.     

Synthesis and Properties of Alkoxyethyl β‐d‐Xylopyranoside

In order to improve the water solubility of sugar‐based surfactants, alkyl β‐d‐ xylopyranosides, novel sugar‐based surfactants, 1,2‐trans alkoxyethyl β‐d‐ xylopyranosides, with alkyl chain length n = 6–12 were stereoselectively prepared by the trichloroacetimidate method. Their properties including hydrophilic–lipophilic balance (HLB) number, water solubility, surface tension, emulsification, foamability, thermotropic liquid crystal, and hygroscopicity were investigated. The results indicated that their HLB number decreased with increase of alkyl chain, the water solubility improved since the hydrophilic oxyethene (─OCH₂CH₂─) fragment was introduced. The dissolution process was entropy driven at 25–45 °C for alkyl chain length n = 6–10. Octyloxyethyl β‐d‐ xylopyranoside had the best foaming ability. Nonyloxyethyl β‐d‐ xylopyranoside had the best foam stability and the emulsifying ability was better in toluene/water system than in rapeseed oil/water system. The surface tension of in aqueous solution dropped to 27.8 mN m^?1 at the critical micelle concentration, and it also showed the most distinct thermotropic liquid phases with cross pattern texture upon heating and the fan schlieren texture on cooling. Hexyloxyethyl β‐d‐ xylopyranoside possessed the strongest hygroscopicity. Based on the effective improvement of water solubility, the prepared alkoxyethyl β‐d‐ xylopyranosides showed excellent surface activity and are expected to develop their practical application as a class of novel sugar‐based surfactants.     

The Effect of Surfactant Concentration on the Flotation of Hydrocarbons from Their Emulsions. I. Removal of Mesitylene

Abstract

The removal of mesitylene from its aqueous emulsions by the foaming method was investigated. As frothing agents, sodium dodecylbenzenesulfonate (NaDBS) and cetyltrimethylammonium bromide (CTMABr) were used. The influence of the concentration of those compounds on the removal effect of mesitylene is presented. It was found that the effective index of the surfactants is best when their concentration in the foamed mixture is the lowest possible one. Taking into account the foam stability, these concentrations equal 1.0 × 10^?4 mol/dm³ for CTMABr and 1.7 × 10^?4 mol/dm³ for NaDBS. The effect of the initial mesitylene concentration in the emulsion on its removal was also determined.     

A study of foaming problems in a CO2 removal system

Carbon dioxide (CO₂) is removed by absorption in hot potassium carbonate (HPC) solution in ammonia plant. Under actual field conditions, HPC solution can be easily contaminated by system impurities in the circulating solution. These impurities enhance foaming in the CO₂ removal system, which has significant effects in reducing equipment capacity and increasing processing time. In this study, it is assumed that the main cause of foaming is the presence of potassium soap in the HPC solution. The effects on foaming problems of adding calcium oxide have been investigated. The role of a charcoal bed and filtration have also been examined. The results showed that a significant reduction in foam height in an actual field solution can be obtained by using calcium oxide. Values of up to 97% reduction in foam height have been achieved.     

Synergism and Interfacial Property Study of Sodium Lauryl Ether Sulfate and Polysorbate 80 at the Air–Water Interface

Adsorption and micellization behavior of sodium lauryl ether sulfate (SLES) and Polysorbate 80 (PS80) was investigated using equilibrium and dynamic surface tension and foaming measurements. Critical micelle concentration (CMC) was determined using surface tension and dye (Sudan red III) solubilization method with the help of the Wilhelmy plate method and ultraviolet–visible spectroscopic method, respectively. The strength of the interaction for micellization and adsorption between the mixtures are calculated using the β interaction parameter. The SLES-PS80 mixture shows synergistic interaction with β = −8.0. The dynamic and foaming behavior at constant bulk concentration showed a higher t ^* value with lowest foaming at 50% mole fraction of SLES. The emulsification index (EI) of pure SLES, pure PS 80, and 1:1 SLES-PS 80 composition was studied using neem, karanja, and sunflower oils. Karanja and sunflower oils show a higher EI for mixture than the pure surfactants, whereas neem shows a lower EI for mixture than pure surfactants.     

Physicochemical Properties and Phase Behavior of Didecyldimethylammonium Chloride/Alkyl Polyglycoside Surfactant Mixtures

Mixed surfactant systems, used in many formulations, have aroused great attention and interest from researchers and industry due to the possibility of synergism. Alkyl polyglycoside (APG) and didecyldimethylammonium chloride (DDAC) mixtures combine the excellent properties of pure surfactants and play an important role in the development of multi‐functional washing products. To study the synergism between APG and DDAC, the physicochemical properties of different mixed systems have been investigated. The critical micelle concentration (CMC) is about 180 mg·L^?1 and the surface tension at the CMC is about 26.0 mN·m^?1 at a mass fraction of 40 % DDAC (ω_DDAC40 %). The values are significantly lower than pure surfactants. The foaming property shows the best performance at ω_DDAC20 %. When the mass fraction of DDAC is 80 %, the mixture exhibits better wetting and emulsifying properties. Synergism was observed in surface tension, foaming and emulsifying properties, while the wetting ability and detergency exhibited no such effects. Phase behavior of the APG/DDAC/water ternary system has also been carried out by polarized optical microscope. The phase diagram is characterized by a micellar phase, a region where lamellar and micellar phases coexist and a lamellar phase.     

Preparation and properties of water‐soluble polyester surfactants. III. Preparation and wetting properties of polyethylene glycol–polydimethylsiloxane polyester surfactants

A novel series of water‐soluble polyethylene glycol–polydimethylsiloxane (PEG–Silicone) polyesters was prepared by reacting organopolysiloxane with hydroxyl‐terminated polyester. The polyesters are obtained by the polymerization of maleic anhydride (MA) and PEGs (number‐average molecular weights M _n = 2000–10,000). FTIR, ¹H‐NMR, and elemental analysis were employed to characterized the structures of these compounds. These compounds exhibit good surface activities such as surface tension and low foaming. The influence of the PEG–Silicone polyester surfactants introduced at various concentrations (0.1–2 wt %) was examined by the contact angle method. The measurements performed with various solid substrates indicated that, at comparable concentrations, the PEG–Silicone polyester surfactants were shown to be more efficient for wetting PET and glass. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1236–1241, 2003     

Incorporation of fluorinated surfactants into polysulfone films and asymmetric gas separation membranes

This study investigated the effect of incorporating strong surfactants into hollow fiber membranes and solution cast films made from polysulfone (PSF). During membrane formation, various (mostly fluorinated) surfactants were added to the spinning solution, quench medium, and bore fluid. Both the gas transport properties and the membrane structure were affected. Some membranes showed a modest increase in selectivity or in permeation rate. At low concentrations the addition of perfluoro ammonium octanoate (PAO) increased the O₂ permeation rate by 44% with only a small loss of selectivity. Surfactants were also incorporated into dense PSF films by solution casting. Only pure PSF films and those with low concentrations of short‐tailed fluorinated surfactants were clear and transparent; higher concentrations and other surfactants yielded cloudy or defective films. The presence of surfactants decreased the glass transition temperature of PSF to varying extents. Increased total and polar surface free energy correlated with changes in the gas transport properties. It is proposed that the surfactants interact with the polymer both during membrane and film formation, and also affect chain packing after the solvent has been removed. SEM images confirmed that membranes with surfactants have larger voids in the porous matrix of the membrane. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 163–175, 1999     

Relationship of structure to properties of surfactants. 16. Linear decyldiphenylether sulfonates

The properties of some well-characterized sodium linear decyldiphenylether (C₁₀DPE)sulfonates have been studied. Among the properties investigated are dynamic and equilibrium surface tension, critical micelle concentration (CMC), area per molecule at the aqueous solution/air interface, wetting time by the Draves technique, foaming by the Ross-Miles method, solubilization, and hydrotropy. The decyldiphenylether moiety appears to be equivalent to a terminally substituted straight alkyl chain of 16 carbon atoms. The trialkyl- and dialkyl-mono-sulfonates have solubilities of < 0.01 g/dm³ in water, but are readily soluble in hexane. The didecyldiphenyl ether disulfonate (DADS) has a very low CMC value (1.0 × 10⁻⁵ mol dm⁻³) in aqueous 0.1 N Na⁺ solution (NaCl), characteristic of surfactants with two hydrophilic and two hydrophobic groups. It also has a much larger area per molecule at the aqueous solution/air interface than the monodecyldiphenyl-ether monosulfonate (MAMS) and a much higher surface tension at the CMC. MAMS has a much lower surface tension at a surface age of 1 second (γ_1s) than either DADS or the monodecyldiphenylether disulfonate (MADS). In agreement with γ_1s and γ_eq values, wetting times increase in the order: MAMS < DADS < MADS and initial foam heights decrease in the order: MAMS > DADS > MADS. Solubilization for three water-insoluble surfactants decreases in the order: DADS > MAMS > MADS, while hydrotropy is most pronounced with the disulfonates.     

Batch foaming of SAN/clay nanocomposites with scCO2: A very tunable way of controlling the cellular morphology

This paper aims at elucidating some important parameters affecting the cellular morphology of poly(styrene-co-acrylonitrile) (SAN)/clay nanocomposite foams prepared with the supercritical CO₂ technology. Prior to foaming experiments, the SAN/CO₂ system has first been studied. The effect of nanoclay on CO₂ sorption/desorption rate into/from SAN is assessed with a gravimetric method. Ideal saturation conditions are then deduced in view of the foaming process. Nanocomposites foaming has first been performed with the one-step foaming process, also called depressurization foaming. Foams with different cellular morphology have been obtained depending on nanoclay dispersion level and foaming conditions. While foaming at low temperature (40 °C) leads to foams with the highest cell density (∼10¹²-10¹⁴ cells/cm³), the foam expansion is restricted (d∼0.7-0.8 g/cm³). This drawback has been overcome with the use of the two-step foaming process, also called solid-state foaming, where foam expansion occurs during sample dipping in a hot oil bath (d∼0.1-0.5 g/cm³). Different foaming parameters have been varied, and some schemes have been drawn to summarize the characteristics of the foams prepared - cell size, cell density, foam density - depending on both the foaming conditions and nanoclay addition. This result thus illustrates the huge flexibility of the supercritical CO₂ batch foaming process for tuning the foam cellular morphology.