Role played by the head size of some non‐ionic surfactants on their adsorption onto montmorillonite clay

Sorption behavior of polyoxethylene(n)monooleate series [Ol(EO)_n] onto montmorillonite clay was studied at 25°C to investigate the influence of the surfactant's head size on the sorption process. All the tested surfactants exhibited L‐shaped isotherms that means a strong interaction between the adsorbent and the adsorbate. Also, all the obtained isotherms ended with a drastic increase in the isotherm slope at nearly constant equilibrium concentration. This abrupt increase reflected the fairly high affinity of the tested surfactants to the clay surface at high bulk concentration region. The maximum amount adsorbed at the plateau region, Γ_max, was calculated according to the Langmuir adsorption theory and followed the order: Ol(EO)₁₄ > Ol(EO)₂₀ < Ol(EO)₄₀ < Ol(EO)₈₀. In case of short ethylene oxide (EO) chain, Γ_max decreased with the increase in the chain length; but a reverse result was obtained in case of surfactants with longer EO chain length (20 to 80 units). The free energy of adsorption, ΔG°_ad, had negative values indicating the spontaneous adsorption of surfactant molecules onto clay. The values of ΔG°_ad increased with increasing EO units from 14 to 20 units and decreased with further elongation in the EO chain from 20 to 80 units. Copyright © 2004 John Wiley & Sons, Ltd.     

Adsorption of Some Surfactants onto Polyvinyl Alcohol as Hydrophobic Polymer Surface

The adsorption of different types of nonionic and anionic surfactants from aqueous solutions onto polyvinyl alcohol has been studied at different temperatures using surface tension measurements. The nonionic surfactants show Langmuirian L-shape isotherms whereas the adsorption isotherms of the anionic surfactants exhibit segmoidal shape. The experimental adsorption isotherms could be fitted to the Langmuir equation and the values of Γ_max and A_min have been calculated. The effect of temperature on the adsorption process as well as on both efficiency and effectiveness of adsorption has been studied.     

Adsorption Behavior and Mechanisms of Surfactants by Farmland Soils in Northeast China

The adsorption of two nonionic surfactants polyethylene glycol tert-octylphenyl ether Triton X-100 (TX-100), polyoxyethylene lauryl ether(Brij35) and an anionic surfactant sodium dodecyl benzene sulfonate(SDBS) by two soils(S1, S2) of different natures and their respective organic-matter-extracted samples(S3, S4) were investigated. These adsorption isotherms show different adsorption stages of different types of surfactants by soils. The data fitted Langmuir equation very well. The adsorption maximum capaci...     

Adsorption of Copper (II) Ions onto Surfactant-Modified Oil Palm Leaf Powder

Il palm leaf powder (OPLP), an agricultural solid waste was used as adsorbent for the removal of copper (II) ions after modification with an anionic surfactant, sodium dodecyl benzene sulfonate (SDBS), CH₃(CH₂)₁₁C₆H₄SO₃Na. The copper (II) ions adsorption is highly dependent on pH and maximum removal was observed at pH 6, above which copper (II) started to precipitate. The equilibrium adsorption data were fitted into the Langmuir and Freundlich isotherms. The Freundlich isotherm model fitted well to data with 0.989 regression coefficient (R²). The kinetics of the adsorption of copper (II) ions onto the surfactant-modified OPLP was best described by a pseudo-second-order model. Comparison of this SDBS-modified-OPLP to previously investigated adsorbents showed comparably good result, offering this material as a promising adsorbent for the treatment of waste waters containing lower concentrations of copper (II) ions.     

Interfacial and Thermodynamic Properties of Anionic‐Nonionic Mixed Surfactant System: Influence of Hydrophobic Chain Length of the Nonionic Surfactant

The influence of hydrophobic chain length in nonionic surfactants on interfacial and thermodynamics properties of a binary anionic‐nonionic mixed surfactant was investigated. In this study, nonionic surfactants lauric‐monoethanolamide (C₁₂ MEA) and myrisitic‐monoethanolamide (C₁₄ MEA) were mixed with an anionic surfactant, α‐olefin sulfonate (AOS). The critical micelle concentration (cmc), maximum surface excess (Γ_max), and minimum area per molecule (A_min) were obtained from surface tension isotherms at various temperatures. The thermodynamic parameters of micellization and adsorption were also computed. Micellar aggregation number (N_agg), micropolarity, and binding constant (K_sv) of pure and mixed surfactant system was calculated by fluorescence measurements. Rubingh's method was applied to calculate interaction parameters for the mixed surfactant systems.     

表面活性剂和聚乙烯吡咯烷酮在ZrO2上的吸附对其悬浮体稳定性的影响

研究了水溶液中十二烷基苯磺酸钠（ＳＤＢＳ）、溴代十四烷基吡啶（ＴＰＢ）和聚乙烯吡咯烷酮（ＰＶＰ）在ＺｒＯ２上的吸附及对ＺｒＯ２水悬浮体稳定性的影响。结果表明：ｐＨ＝２．４时ＳＤＢＳ在ＺｒＯ２上的吸附等湿线为ＬＳ型，ｐＨ＝７．０时ＴＰＢ的吸附等温线为Ｓ型，吸附等温线与ＺｒＯ２粒子ζ电势变化同线有大体一致的关系。在最大吸附量时ＺｒＯ２粒子ζ电势较大，且吸附的表面活性剂离子形成大部分亲水基朝向水相的表面     

Effect of Organic Solvents on the Electrodeposition of Copper from Acidified CuSO4

Using Guerbet tetradecyl alcohol C₁₄GA (synthesized by Guerbet reaction using 1-heptanol as raw material) as intermediate, sodium Guerbet tetradecyl polyoxyethylene ether sulfates [C₁₄GA(EO)_nS, n = 1, 2, 4] were obtained through following steps: synthesizing Guerbet tetradecyl polyoxyethylene ether alcohols [C₁₄GA(EO)_nH, n = 1, 2, 4] by Williamson reaction, then esterifying with chlorosulfonic acid so as to form Guerbet tetradecyl polyoxyethylene ether alcohol sulfates [C₁₄GA(EO)_nSO₃H, n = 1, 2, 4], and finally neutralizing with sodium hydroxide; while sodium Guerbet tetradecyl sulfate(C₁₄GAS) was synthesized only through esterifying and neutralizing reactions. The structures of these anionic surfactants were determined by infrared, nuclear magnetic resonance, and element analysis. The surface activity of these surfactants was studied by means of surface tension. The results have shown that these surfactants possess higher surface activity than the common surfactant C₁₂H₂₅OSO₃Na. Branched-tail structure coming from Guerbet alcohol makes the anionic surfactant (C₁₄GAS) have higher critical micelle concentration (CMC) and better effectiveness in lowering the interface tension between air and water than their linear counterpart (C₁₄H₂₉OSO₃Na). Introducing oxyethyene group into the place between head group and tail group of the surfactant molecule with branched tail can lower the CMC, γ_cmc, and Krafft point. And the effectiveness for reducing the CMC, γ_cmc, Γ_max, and Krafft point of surfactant increased with the increase of oxyethylene group number (n = 1, 2, 4). The relationship between the molecular structure and surface activity of surfactant is discussed.     

Polychlorinated Biphenyls-contaminated Soil Washing with Mixed Surfactants Enhanced by Electrokinetics

On the basis of comparing the adsorption loss of different surfactants[single nonionic surfactant sorbitanmonooleatepolyoxyethylene ether(Tween 80), anionic surfactant sodium dodecyl benzene sulfonate(SDBS), and mixed surfactants Tween 80/SDBS(3:2), Tween 80/SDBS(4:1)] and their performance in the enhancement of polychlorinated biphenyls(PCBs) desorption from soil, the impact of electric field intensity on the desorption of PCBs and the transport of surfactants in washing resulted solution were investigated in this study. With regard to the remediation cost, 1000 mg/L mixed Tween 80/SDBS(3:2) was recognized as an optimum concentration in the remediation of PCBs-contaminated soil, because Tween 80/SDBS(3:2) had the highest washing capacity and relatively low adsorption loss onto soil. Electrokinetics can enhance the washing efficiency of PCBs-contaminated soil by Tween 80/SDBS(3:2) effectively and safely at an electric field intensity of 1.5 V/cm for 10 d, for the desorption of PCBs was 1.57 times more than that without electrokinetics, and the most of organic residue in washing resulted solution was removed in an electrical field to avoid the possible secondary contamination risk.     

Effect of Polymer on Dynamic Interfacial Tensions of Anionic–nonionic Surfactant Solutions

The dynamic interfacial tensions (IFTs) of enhanced oil recovery (EOR) surfactant/polymer systems against n-decane have been investigated using a spinning drop interfacial tensiometer in this paper. Two anionic–nonionic surfactants with different hydrophilic groups, C₈PO₆EO₃S (6-3) and C₈PO₆EO₆S (6-6), were selected as model surfactants. Partially hydrolyzed polyacrylamide (HPAM) and hydrophobically modified polyacrylamide (HMPAM) were employed. The influences of surfactant concentration, temperature, polymer concentration, and oleic acid in the oil on IFTs have been studied. The experimental results show that anionic–nonionic surfactants can form compact adsorption films and reach ultralow IFT (10^?3 mN/m) under optimum conditions. The addition of polymer has great influence on dynamic IFTs between surfactant solutions and n-decane mainly by the formation of looser mixed films resulting from the penetration of polymer chains into the interface. The compact surfactant film will also be weakened by the competitive adsorption of oleic acid, which results in the increase of IFT. Moreover, the penetration of polymer chains will be further destroyed surfactant/polymer mixed layer and lead to the obvious increase of IFT. On the other hand, polymers show little effect on the IFTs of 6-6 systems than those of 6-3 because of the hindrance of longer EO chain of 6-6 at the interface.     

Salt Effect,Surface, and Aggregation Properties of Binary Surfactant Mixtures of a Nonionic Gemini Surfactant (HBA(EO)80) with Anionic Surfactants

Nonionic gemini surfactants HBA(EO)₈₀ were synthesized and characterized by means of surface tension measurements. CMCs of two mixed system, nonionic gemini mixed with anionic gemini (HBA(EO)₈₀/C11pPHCNa) and nonionic gemini mixed with anionic monomeric (HBA(EO)₈₀/SL) and the effect of salt on the two mixed system were investigated. Freeze-fracture transmission electron microscopy and scanning electron microscopy were used to investigate the mixed aggregates' morphologies. The results show that large spherical aggregates were formed in the mixed solution, which trend to transfer into micelles with the increases of the salt concentration.     

Equilibrium surface adsorption behavior in complex anionic/nonionic surfactant mixtures

Neutron reflectivity (NR) and small angle neutron scattering (SANS) have been used to investigate the equilibrium surface adsorption behavior and the solution microstructure of mixtures of the anionic surfactant sodium 6-dodecyl benzene-4 sulfonate (SDBS) with the nonionic surfactants monododecyl octaethylene glycol (C12EO8) and monododecyl triiscosaethylene glycol (C12EO23). In the SDBS/C12EO8 and SDBS/C12EO23 solutions, small globular mixed micelles are formed. However, the addition of Ca2+ ions to SDBS/C12EO8 results in a transition to a vesicle phase or a mixed vesicle/micellar phase for SDBS rich compositions. In contrast, this transition hardly exists for the SDBS/C12EO23 mixture, and occurs only in a narrow composition region which is rich in SDBS. The adsorption of the SDBS/C12EO8 mixture at the air-solution interface is in the form of a mixed monolayer, with a composition variation that is not consistent with ideal mixing. In water and in the presence of NaCl, the nonideality can be broadly accounted for by regular solution theory (RST). At solution compositions rich in SDBS, the addition of Ca2+ ions results in the formation of multilayer structures at the interface. The composition range over which multilayer formation exists depends upon the Ca2+ concentration added. In comparison, the addition of a simple monovalent electrolyte, NaCl, at the same ionic strength does not have the same impact upon the adsorption, and the surface structure remains as a monolayer. Correspondingly, in solution, the mixed surfactant aggregates remain as relatively small globular micelles. In the presence of Ca2+ counterions, the variation in surface composition with solution composition is not well described by RST over the entire composition range. Furthermore, the mixing behavior is not strongly correlated with variations in the solution microstructure, as observed in other related systems.     

Adsorption of Pure Nonionic Alkylethoxylated Surfactants down to Low Concentrations at a Silica/Water Interface as Determined Using a HPLC Technique

The adsorption of pure nonionic alkylethoxylated surfactants of the C₁₂E_nseries at silica/water interface has been determined using a very precise HPLC technique. The number of ethoxylated groups was varied from 2 to 9. The adsorption isotherms were constructed with special attention to the very low surface coverage domain. It is shown that at very low concentration, the adsorption amounts are higher as the number of ethoxylated groups increases but the reverse trend is found at higher surfactant concentration and above the critical micelle concentration. It is shown that this behavior is the consequence of the interplay of the primary and secondary adsorption mechanisms depending upon the length of the ethoxylated chain. The maximum adsorption quantities is not a linear function of the number of ethoxylated groups. This and other observations confirm the viewpoint that the behavior of nonionic surfactant aggregates adsorbed at a hydrophilic surface carries many similarities with the properties of this class of nonionic surfactant aggregates in bulk aqueous solutions.     

ADSORPTION OF NONIONIC AND ANIONIC POLYMERS ON γ-ALUMINA AND NA-MONTMORILLONITE AND THEIR MIXTURES

Adsorption isotherms of nonionic polyvinylpyrrolidone (PVP) and anionic ionized polyacrylic acid (PAA) polymers on single Na-montmorillonite clay and γ-alumina adsorbents in 0.01M NaCl and pH 5.6 are reported and compared to results obtained with aqueous adsorbent mixtures. Microeiectrophoretic behaviours of adsorbents are also observed.

It can be shown that antagonistic effects due to interactions between oppositely charged adsorbent surfaces largely limit the nonionic PVP adsorption.     

Hexaconazole-Micelle Nanodelivery System Prepared Using Different Surfactants for Ganoderma Antifungal Application

Reports on fungicide-based agronanochemicals in combating disastrous basal stem rot disease in the oil palm industry are scant. Herein, we describe the potential of fungicide nanodelivery agents based on hexaconazole-micelle systems produced using three different surfactants; sodium dodecylbenze sulfonate (SDBS), sodium dodecyl sulfate (SDS) and Tween 80 (T80). The resulting nanodelivery systems were characterized and the results supported the encapsulation of the fungicide into the micelles of the surfactants. We have investigated in detail the size-dependent effects of the as-synthesized micelles towards the inhibition growth of Ganoderma Boninense fungi. All the nanodelivery systems indicate that their size decreased as the surfactant concentration was increased, and it directly affects the fungal inhibition. It was also found that Tween 80, a non-ionic surfactant gave the lowest effective concentration, the EC₅₀ value of 2, on the pathogenic fungus Ganoderma boninense compared to the other anionic surfactants; SDBS and SDS. This study opens up a new generation of agronanofungicide of better efficacy for Ganoderma disease treatment.     

Surfactant fouling of nanofiltration membranes: measurements and mechanisms.

Fouling of nanofiltration membranes is studied during filtration of aqueous surfactant solutions under different conditions. To this purpose, four typical nanofiltration membranes (Desal51HL, NF270, NTR7450 and NFPES10) and three typical surfactants (nonionic neodol, anionic SDBS and cationic cetrimide) are selected. Fouling is studied as a function of the surfactant concentration, with and without addition of an electrolyte (NaCl), at different pH and when filtering a mixture of surfactants. Adsorption experiments and hydrophobicity measurements (to study the orientation of the surfactants on the membrane surface) are also performed under the different conditions. The least membrane fouling is found for the anionic surfactant SDBS, while for the cationic surfactant cetrimide very low relative fluxes are observed. Neodol shows an intermediate degree of fouling. Both hydrophobic and electrostatic interactions (in the case of ionic surfactants) between the membrane surface and the surfactant explain the degree of adsorption and hence fouling, as membrane fouling is correlated with the amount of adsorbed surfactant. The difference between cetrimide and SDBS becomes especially visible when changing the pH: increasing the pH leads not only to an opposite orientation of the adsorbed surfactants, but also to an opposite trend in adsorbed amount and membrane fouling. This study permits selection of an optimal nanofiltration membrane to recycle wastewater containing surfactants in the carwash industry. The optimal choice would be a hydrophilic membrane with a low molecular weight cut-off and a small negative surface charge at neutral pH. Cationic surfactants in the wastewater should also be avoided as much as possible.     

ADSORPTION ISOTHERMS OF SOME COMMERCIAL SURFACTANTS ONTO CLAY. COMPARISONS WITH SYNTHESIS SURFACTANT

Abstract

The adsorption of polyoxyethylene mono soya bean fatty acid [Soy (EO)_20,40 and ₈₀] and polyoxyethylene (80) monolinoleate [Li(EO)₈₀] onto Na-montmorillonite has been determined at 30°C. The adsorption isotherms of all the tested surfactants exhibit an L-shaped following the Langmuirian model. The experimental adsorption data are fitted to Langmuir adsorption equation, the maximum amount adsorbed, Γ_max, and the minimum area occupied per molecule, A_max at the pseudo-plateau have been calculated. Γ_max value increases with the increase in the number of ethylene oxide units following the order, Soy (EO)₂₀ < Soy (EO)₄₀ Soy (EO) ? Li (EO)₈₀. Both Soy (EO)₈₀ and Li (EO)₈₀ nearly show the same adsorption behavior.     

Potentiometric Surfactant Sensor Based on 1,3-Dihexadecyl-1H-benzo[d]imidazol-3-ium for Anionic Surfactants in Detergents and Household Care Products

A 1,3-dihexadecyl-1H-benzo[d]imidazol-3-ium-tetraphenylborate (DHBI-TPB) ion-pair implemented in DHBI-TPB surfactant sensor was used for the potentiometric quantification of anionic surfactants in detergents and commercial household care products. The DHBI-TPB ion-pair was characterized by FTIR spectroscopy and computational analysis which revealed a crucial contribution of the C–H∙∙∙π contacts for the optimal complex formation. The DHBI-TPB sensor potentiometric response showed excellent analytical properties and Nernstian slope for SDS (60.1 mV/decade) with LOD 3.2 × 10⁻⁷ M; and DBS (58.4 mV/decade) with LOD 6.1 × 10⁻⁷ M was obtained. The sensor possesses exceptional resistance to different organic and inorganic interferences in broad pH (2–10) range. DMIC used as a titrant demonstrated superior analytical performances for potentiometric titrations of SDS, compared to other tested cationic surfactants (DMIC > CTAB > CPC > Hyamine 1622). The combination of DHBI-TPB sensor and DMIC was successfully employed to perform titrations of the highly soluble alkane sulfonate homologues. Nonionic surfactants (increased concentration and number of EO groups) had a negative impact on anionic surfactant titration curves and a signal change. The DHBI-TPB sensor was effectively employed for the determination of technical grade anionic surfactants presenting the recoveries from 99.5 to 101.3%. The sensor was applied on twelve powered samples as well as liquid-gel and handwashing home care detergents containing anionic surfactants. The obtained results showed good agreement compared to the outcomes measured by ISE surfactant sensor and a two-phase titration method. The developed DHBI-TPB surfactant sensor could be used for quality control in industry and has great potential in environmental monitoring.     

Synergistic interactions between zwitterionic surfactants derived from olive oil and an anionic surfactant

Abstract

The surface properties of the mixtures of zwitterionic surfactants derived from olive oil (carboxylbetaine-OCB and sulfobetaine-OSB) and anionic surfactant-sodium dodecylbenzene sulfonate (SDBS) at different mole fractions were investigated by surface tension measurement. The influences of the addition of inorganic salts (NaCl, MgCl₂) on the surface activities in OCB/SDBS and OSB/SDBS systems were also studied. The result shows that the two mixed systems possess lower CMC values and higher surface activities over all mole fractions studied than their individual components. Meanwhile, the noticeable synergistic interactions of OCB/SDBS and OSB/SDBS were determined by the micelle interaction parameter (β^m) according to regular solution theory. It is observed that the mixed OCB/SDBS system at α_OCB?=?0.6 and the mixed OSB/SDBS system at α_OSB?=?0.6 exhibit the strongest synergism. In addition, the binary surfactant mixtures performed better surface activities upon addition of inorganic salts and the different valence state of mental ions of the inorganic salts had different surface ability effect on the mixed system: Mg²⁺?>?Na⁺.     

Effect of self‐assemblies of various surfactants in their single and mixed states on the BZ oscillatory reaction

Micelles of different surfactants are well known to affect chemical equilibria and reactivities by selectively sequestering the reagent substrates through electrostatic and hydrophobic interactions. In this article, the effects of micelles of various surfactants on different parameters of the Ce(IV)‐catalyzed Belousov–Zhabotinsky (BZ) oscillatory reaction at 35°C in nonstirred closed conditions are studied by employing spectrophotometry and tensiometry. Surfactants used in this study are the cationics hexadecyltrimethylammonium bromide (CTAB) and pentamethylene‐1,5‐bis(N‐hexadecyl‐N,N‐dimethylammonium)bromide gemini (Gemini), anionic sodium dodecylbenzene sulfonate (SDBS), and nonionic Brij58, whereas the binary surfactant systems used are cationic–nonionic CTAB+Brij58 and anionic–nonionic SDBS+Brij58. The results revealed that the induction period shows a definite variation with increasing concentration of different surfactants above their critical micelle concentration (cmc). The amplitudes of oscillation and absorbance maxima and minima are enhanced in the presence of micelles of CTAB and Gemini surfactants, whereas micelles of SDBS and Brij58 have almost no effect on the nature of the oscillations. However, mixed micelles of CTAB+Brij58 and SDBS+Brij58 binary mixtures show a quite different effect on the overall behavior of the oscillations. The enhanced effect of CTAB and Gemini surfactants on the overall nature of oscillations has been attributed to the positive charge on the surface of their micelles and to some extent on the presence of nitrogen in their head group. The effect of mixed binary micelles may be attributed to their synergistic nature. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 659–668, 2010     

Spontaneous Formation of Biocompatible Vesicles in Aqueous Mixtures of Amino Acid‐Based Cationic Surfactants and SDS/SDBS

The spontaneous formation of vesicles by six amino acid‐based cationic surfactants and two anionic surfactants (sodium dodecylbenzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS)) is reported. The head‐group structure of the cationic surfactants is minutely altered to understand their effect on vesicle formation. To establish the regulatory role of the aromatic group in self‐aggregation, both aliphatic and aromatic side‐chain‐substituted amino acid‐based cationic surfactants are used. The presence of aromaticity in any one of the constituents favors the formation of vesicles by cationic/anionic surfactant mixtures. The formation of vesicles is primarily dependent on the balance between the hydrophobicity and hydrophilicity of both cationic and anionic surfactants. Vesicle formation is characterized by surface tension, fluorescence anisotropy, transmission electron microscopy, dynamic light scattering, and phase diagrams. These vesicles are thermally stable up to 65 °C, determined by temperature‐dependent fluorescence anisotropy. According to the MTT assay, these catanionic vesicles are nontoxic to NIH3T3 cells, thus indicating their wider applicability as delivery vehicles to cells. Among the six cationic surfactants examined, tryptophan‐ and tyrosine‐based surfactants have the ability to reduce HAuCl₄ to gold nanoparticles (GNPs), which is utilized to obtain in‐situ‐synthesized GNPs entrapped in vesicles without the need for any external reducing agent.