Investigations of First Adsorption Step of Cationic Dimeric (Gemini) Surfactants onto Silica Surfaces by Analytical and Calorimetric Methods

doi:10.1006/jcis.2001.7943

Journal of Colloid and Interface Science

Volume 243, Issue 2, 15 November 2001, Pages 525-527

https://doi.org/10.1006/jcis.2001.7943 Get rights and content

Abstract

This paper reports new results on the adsorption of cationic dimeric surfactants (12–s–12 surfactants, where s is the carbon number of the polymethylene spacer) on adsorbents with different surface functions, namely raw and HCl-treated silica. These results were obtained by traditional methods (adsorption isotherms, electrophoretic mobility, and chemical analysis of the equilibrated supernatant) and microcalorimetry. The results showed that the stoichiometry of the first step of the adsorption (ion-exchange step) varies strongly with the spacer carbon number. The binding of one surfactant to the surface brings about the release of between 1 and 2 sodium ions as the spacer carbon number is increased from 2 to 10. Thus the surfactant binding to the surface involves one head group for the 12–2–12 surfactant (short spacer) and two head groups for the 12–10–12 surfactant (long spacer). These results suggest the use of dimeric surfactants as molecular rulers to study the distribution of charged sites on surfaces. The microcalorimetric experiments clearly showed the two adsorption steps. The ion-exchange step gives rise to an endothermal effect having an amplitude that depends strongly on the spacer carbon number. The second adsorption step associated with the formation of surfactant aggregates gives rise to an exothermal effect that also depends on s.

References (15)

L. Grosmaire et al.
J. Colloid Interface Sci.
(2001)
C. Chorro et al.
J. Colloid Interface Sci.
(1998)
M. Chorro et al.
J. Colloid Interface Sci.
(1999)
A. Fan et al.
Langmuir
(1997)
J. Zajac et al.
P. Somasundaran et al.
J. Phys. Chem.
(1966)
B.H. Birjsterbosch
J. Colloid Interface Sci.
(1974)

There are more references available in the full text version of this article.

Cited by (18)

Physicochemical and solution properties of quaternary-ammonium-salt-type amphiphilic gemini ionic liquids with spacers containing oxygen or nitrogen
2020, Colloids and Surfaces A: Physicochemical and Engineering Aspects
Citation Excerpt :
For example, Zana et al. reported the effects of the spacer chain length on the aggregation properties in an aqueous solution of quaternary-ammonium-salt-type cationic gemini surfactants C12-s-C12. The aggregates formed by C12-s-C12 changed from wormlike micelles to vesicles as the chain lengths of the spacers increased [19–21]. In addition, Bordes et al. reported that the CMC values of surfactants with spacers of the same hydrophobicity and possessing the same distance between hydrophilic groups were approximately the same [22].
Quaternary-ammonium-salt-type amphiphilic gemini compounds 2C_n(Spacer) NTf₂ were synthesized by the quaternization of a tertiary diamine and an n-alkyl bromide, followed by an ion-exchange reaction with potassium bis(trifluoromethanesulfonyl)imide [(Spacer) = (2-O-2), (2-O-2-O-2), (2-N-2), (2/2-N-2), (2/2)-OH, (5), (6), and n represents the alkyl chain lengths; n = 10, 12, 14 for the 2-O-2 spacer, and n = 12 for all others]. The compounds with melting points below 100 °C were treated as ionic liquids during the subsequent measurements. The melting points of the amphiphilic gemini compounds could be arranged in the following order, based on the spacer present: (2/2)-OH >> 2/2-N-2 > (2-N-2) > (2-O-2) > (5) > (6) > (2-O-2-O-2). The melting points for 2C_n(2-O-2) NTf₂ (n = 10, 12), 2C₁₂(2-O-2-O-2) NTf₂, and 2C₁₂(2-N-2) NTf₂ could be reduced to <0 °C. The amphiphilic gemini ionic liquids exhibited significantly lower conductivities and higher viscosities than the corresponding monomeric ionic liquids. This was attributed to a decrease in the mobility of the cationic molecules caused by the gemini structure, in which the two monomeric compounds are connected by a spacer. Furthermore, the amphiphilic gemini ionic liquids, particularly those containing oxygen in the spacer, exhibited efficient adsorption at the air/water interface.
Effect of the spacer length on the electrostatic interactions of cationic gemini surfactant micelles with trianionic curcumin
2013, Colloids and Surfaces A: Physicochemical and Engineering Aspects
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Like in the micelles of C12CsC12Br2 (s = 2–4), only two negative charges of Cur3− bind to the headgroups from two neighboring aggregated C12C12C12Br2 molecules by electrostatic attraction, except one side negative charge in the phenolic part of Cur3−. Meanwhile, compared to the surfactants of C12CsC12Br2 (s = 2–6), the much long spacer in C12C12C12Br2 makes the two ionic headgroups more separated and reduces the charge density of surfactant headgroups to a greater extent, as suggested by the reported data of micelle ionization degree and zeta potential of C12CsC12Br2 micelles [40,41]. Therefore, the electrostatic attraction of Cur3− with C12C12C12Br2 micelle is weaker than C12C6C12Br2 micelle.
The absorption and fluorescence measurements have been used to study the interactions between cationic gemini surfactant micelles of alkanediyl-α,ω-bis(dodecyldimethylammonium bromide) (C₁₂C_sC₁₂Br₂, where s = 2, 3, 4, 6, and 12, indicating the number of carbons in the spacer) with trianionic curcumin (Cur³⁻) at pH 13. With increasing spacer length of gemini surfactant, the maximum intensities of absorption and fluorescence peaks of Cur³⁻ give the highest values at s = 6, reflecting that the spacer length of gemini surfactant significantly regulates the electrostatic attractive interactions between C₁₂C_sC₁₂Br₂ micelles and Cur³⁻. The maximum fluorescence intensity of Cur³⁻ in C₁₂C₆C₁₂Br₂ micelle shows increasing tendency at 0–100 mM sodium bromide concentration (C_NaBr), but decreases above C_NaBr = 120 mM. This result is explained in terms of the enhanced electrostatic attraction of Cur³⁻ with C₁₂C₆C₁₂Br₂ micelle at low salt concentrations and the reduced electrostatic attraction at high salt amounts. The determined pK_a1 values of curcumin in C₁₂C_sC₁₂Br₂ micelles support the strongest electrostatic association between C₁₂C₆C₁₂Br₂ micelle and anionic Cur⁻. The interaction mechanisms of C₁₂C_sC₁₂Br₂ micelles with Cur³⁻ have been further proposed at s = 2–4, s = 6, and s = 12, which is related to the matching of the positive charges in C₁₂C_sC₁₂Br₂ micelles to the negative charges in Cur³⁻.
The interaction of gemini surfactants C<inf>12</inf>-s-C <inf>12</inf>·2Br with aqueous suspension of fumed silica
2012, Energy Procedia
The interaction of Gemini surfactant C₁₂-s-C₁₂2Br with aqueous suspension of fumed silica have been investigated by DLS, Zeta potential, conductivity, pH value and fluorescence. With the increase of surfactant concentration, four regions exist during the adsorption and aggregation process, which can be recognized as ion exchange adsorption, electrostatic repulsion, adsorption layer formation by hydrophobic interactions and free micelle formation. The Gemini surfactant C₁₂-s-C₁₂2Br shows strong adsorption ability on the fumed silica. Zeta potential was turned from negative to positive by the addition of small quantitates of C₁₂-s-C₁₂2Br. The “dispersion-flocculation-dispersion” phenomena was observed for the addition of s=2 during 0.1 to 4 mmol L-1. 5% fumed silica dispersion system can be gelled by s=2 of 1mmol L-1. These phenomena have never been observed for the systems containing s=4 and s=6.
Contribution of <sup>1</sup>H NMR to the investigation of the adsorption of cationic Gemini surfactants with oligooxyethylene spacer group onto silica
2009, Journal of Colloid and Interface Science
Citation Excerpt :
For these purposes, it is essential to shed light on the adsorption mechanism, which depends simultaneously on the nature of the adsorbing species, the properties of the solid surface and the composition of the aqueous solution. Previous study showed that the adsorption process of 12-s-12 gemini surfactants on the raw and modified silica surface (SiNa, SiH) were closely related to the spacer length [24]. The adsorbed amount at the surface saturation plateau decreased as the size of the spacer group was lengthened.
The present study aims to investigate the behavior of a series of cationic Gemini surfactants with a hydrophilic spacer at liquid–gas and solid–liquid interfaces, with particular emphasis on the effect of spacer length. Gemini surfactants containing two quaternary ammonium groups bound by an ethylene oxide spacer chain, referred to as 12-EO_x-12 with $x = 1, 3, 7$ and 12 were synthesized. Surface tension measurements were used to show that the hydrophilic spacer with oxyethylene moieties was not fully extended at the air–water interface. With increasing the spacer group size, it became sufficiently flexible to adopt a particular conformation with a loop at the water side of the interface. A combined study by adsorption isotherm measurements and ¹H NMR spectroscopy allowed a detailed description of the adsorption mechanism of these investigated 12-EO_x-12 surfactants, with NMR providing more precise information on the conformation of hydrophilic spacer at the solid–liquid interface. Binding to the silica surface involved one cationic headgroup for the surfactants with a short spacer and the two headgroups for the ones with a long spacer. The number of charged surface sites was estimated by considering the dimeric surfactant as a “molecular ruler.” The small density of adsorption sites gave rise to the formation of pinned surface micelles.
Synergistic adsorption of mixtures of cationic gemini and nonionic sugar-based surfactant on silica
2009, Journal of Colloid and Interface Science
Citation Excerpt :
Since the early 1990's, when the unique properties of gemini surfactants were first reported, there has been considerable interest in them both in the academic and industrial circles [1–5]. Some of the major research work was focused on the characterization of individual gemini surfactants, especially on the effects of structural variations within the gemini surfactants on their solution and adsorption properties, including micellization/aggregation, micellar size, surfactant conformation, and adsorption on various solids [6–21]. As conventional surfactants, geminis can be used in many consumer products such as cleansing, cosmetic, personal care and pharmaceutical products and as micellar catalysts with superior efficacy.
Adsorption behavior of cationic $C_{12} - C_{4} - C_{12}$ gemini surfactant on silica has been investigated, along with that of nonionic surfactant n-dodecyl-β-d-maltoside (DM). While DM alone shows meager adsorption on silica, because of the lack of any electrostatic adsorption, cationic gemini adsorbs significantly on the oppositely charged silica surface. Due to the electrostatic nature of cationic gemini adsorption on silica, solution pH affects adsorption of $C_{12} - C_{4} - C_{12}$ gemini dramatically. Meanwhile, $C_{12} - C_{4} - C_{12}$ gemini hemimicelle size at silica/water interface does not seem to change with solution pH. For the mixtures of DM and cationic $C_{12} - C_{4} - C_{12}$ gemini, there is a sharp increase of DM adsorption at silica/water interface, up to 100 times more than DM alone. After mixing with DM, saturation adsorption of cationic $C_{12} - C_{4} - C_{12}$ gemini decreases, due to competition for adsorption sites from DM. At the same time, in its mixture with DM, there is an increased adsorption of $C_{12} - C_{4} - C_{12}$ gemini in the rising part of the adsorption isotherm. Hydrophobic chain–chain interactions, especially with two hydrophobic chains in one $C_{12} - C_{4} - C_{12}$ gemini molecule, and adsorbed $C_{12} - C_{4} - C_{12}$ gemini molecule acting as an anchor or nucleation sites for forming mixed aggregates with DM on silica surface, are attributed to the marked adsorption synergy between DM and cationic $C_{12} - C_{4} - C_{12}$ gemini. The adsorption of surfactants and their mixtures has a marked effect on silica surface charge and silica's wettability.
Surfactant-enhanced remediation of organic contaminated soil and water
2008, Advances in Colloid and Interface Science
Surfactant based remediation technologies for organic contaminated soil and water (groundwater or surface water) is of increasing importance recently. Surfactants are used to dramatically expedite the process, which in turn, may reduce the treatment time of a site compared to use of water alone. In fact, among the various available remediation technologies for organic contaminated sites, surfactant based process is one of the most innovative technologies. To enhance the application of surfactant based technologies for remediation of organic contaminated sites, it is very important to have a better understanding of the mechanisms involved in this process. This paper will provide an overview of the recent developments in the area of surfactant enhanced soil and groundwater remediation processes, focusing on (i) surfactant adsorption on soil, (ii) micellar solubilization of organic hydrocarbons, (iii) supersolubilization, (iv) density modified displacement, (v) degradation of organic hydrocarbon in presence surfactants, (vi) partitioning of surfactants onto soil and liquid organic phase, (vii) partitioning of contaminants onto soil, and (viii) removal of organics from soil in presence of surfactants.
Surfactant adsorption on soil and/or sediment is an important step in this process as it results in surfactant loss reduced the availability of the surfactants for solubilization. At the same time, adsorbed surfactants will retained in the soil matrix, and may create other environmental problem. The biosurfactants are become promising in this application due to their environmentally friendly nature, nontoxic, low adsorption on to soil, and good solubilization efficiency. Effects of different parameters like the effect of electrolyte, pH, soil mineral and organic content, soil composition etc. on surfactant adsorption are discussed here.
Micellar solubilization is also an important step for removal of organic contaminants from the soil matrix, especially for low aqueous solubility organic contaminants. Influences of different parameters such as single and mixed surfactant system, hydrophilic and hydrophobic chain length, HLB value, temperature, electrolyte, surfactant type that are very important in micellar solubilization are reviewed here. Microemulsion systems show higher capacity of organic hydrocarbons solubilization than the normal micellar system. In the case of biodegradation of organic hydrocarbons, the rate is very slow due to low water solubility and dissolution rate but the presence of surfactants may increase the bioavailability of hydrophobic compounds by solubilization and hence increases the degradation rate. In some cases the presence of it also reduces the rate. In addition to fundamental studies, some laboratory and field studies on removal of organics from contaminated soil are also reviewed to show the applicability of this technology.

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Journal of Colloid and Interface Science

Letter to the editorInvestigations of First Adsorption Step of Cationic Dimeric (Gemini) Surfactants onto Silica Surfaces by Analytical and Calorimetric Methods

Abstract

J. Colloid Interface Sci.

J. Colloid Interface Sci.

J. Colloid Interface Sci.

Langmuir

J. Phys. Chem.

J. Colloid Interface Sci.

Physicochemical and solution properties of quaternary-ammonium-salt-type amphiphilic gemini ionic liquids with spacers containing oxygen or nitrogen

Effect of the spacer length on the electrostatic interactions of cationic gemini surfactant micelles with trianionic curcumin

The interaction of gemini surfactants C<inf>12</inf>-s-C <inf>12</inf>·2Br with aqueous suspension of fumed silica

Contribution of <sup>1</sup>H NMR to the investigation of the adsorption of cationic Gemini surfactants with oligooxyethylene spacer group onto silica

Synergistic adsorption of mixtures of cationic gemini and nonionic sugar-based surfactant on silica

Surfactant-enhanced remediation of organic contaminated soil and water

Letter to the editor
Investigations of First Adsorption Step of Cationic Dimeric (Gemini) Surfactants onto Silica Surfaces by Analytical and Calorimetric Methods