Adsorption Of Anionic Surfactants Research Articles

Effects of ionizable groups on the adsorption of surfactants onto latex particle surfaces

Soap titration of polymeric latices can be used both for the determination of an average latex particle size and as a method for investigating the adsorption of surfactants onto hydrophobic surfaces. This investigation has studied the adsorption of anionic and nonionic surfactants onto polystyrene latex particles in order to develop an understanding of the relationship between surfactant structural characteristics (chain length and end-group) and the area occupied by an adsorbed molecule. As expected the area occupied by a surfactant molecule increased as the ethylene oxide chain length increased for a series of octaphenoxy ethoxylate nonionic surfactants. The results also indicated that in addition to structural factors the adsorption area of a surfactant molecule is also dependent upon the surface charges present on the particle surface. For the nonionic surfactants studied the adsorption area per molecule increased as the number of charges chemically attached to the particle surface increased (increasing surface polarity). For sodium dodecyl sulfate, however, just the opposite trend was observed. The increase in the amount of sodium dodecyl sulfate adsorbed with increasing surface charge may be due to a more extended configuration for the adsorbed surfactant molecules which gives rise to more surfactant—surfactant interactions. These surface charges, which arise from the initiator, may vary widely from one latex to another depending upon the polymerization method and recipe and may be responsible for some of the scatter in previous soap titration results.

Surfactant mixtures as collectors in flotation

The adsorption of mixtures from anionic and non-ionic surfactants on scheelite and calcite was tested with different physicochemical methods to determine the amounts adsorbed, the adsorption heats and the electrophoretic mobilities in dependence on surfactant concentration. The results show that in addition to the adsorption of anionic and non-ionic surfactants on the surface of the mineral, the formation of calcium surfactant salts in the mineral suspension should also be taken into account. The precipitation of calcium salts seems to be clearly reduced by the addition of non-ionic surfactants. As proved by flotation tests, the recovery and selectivity are thus increased with reduced collector dosage when the collector mixtures are used.

Adsorption Mechanism of a Cationic Surfactant on Textiles in Excess Anionic Surfactant Solution

Many studies have been carried out on the mechanism of the adsorption of anionic and cationic surfactants on textiles. The case of cationic and anionic surfactants used in combination has also been reported. In such a case, the cationic surfactant is treated as a dispersion and when used with excess anionic surfactant solution, it is not adsorbed on textiles. In the present research, it was found that if a cationic surfactant is used as a corpuscle (fine solid, over 10 μm) in the presence of excess anionics, adsorption on to various textiles becomes possible.For an understanding of this phenomenon, the work of adhesion (Wa) between an anionic/cationic surfactant complex and the surface of a textile was calculated, measuring the contact angle of 2 liquids with the complex by Wu's equation. Wa and the amount of adsorbed cationic surfactant on textiles were found to show a very close correlation.Thus, in an excess anionic surfactant solution, an anionic/cationic surfactant complex is apparently formed on the surface of a corpuscle of a cationic surfactant, and the work of adhession between this complex and each textile is related to the adsorption (or deposition) of a cationic surfactant on textiles.

Interfacial electrical properties of electrogenerated bubbles

Electrophoresis measurements on bubbles of electrogenerated hydrogen, oxygen and chlorine rising in a lateral electric field, are reported. In surfactant-free solutions, all bubbles displayed a point of zero charge of pH 2–3, i.e. they were negatively charged at pH > 3 and positively charged at pH < 2. The bubble diameter and electric field strength dependence of the electrophoretic mobilities, coupled with bubble rise rate measurements, indicated that the gas—aqueous solution interface was mobile, such that classical electrophoresis theory for solid particles could not be applied. Adsorption of anionic or cationic surfactants, in addition to modifying the apparent bubble charge, also tended to rigidify the bubble surface, so that at monolayer coverage the bubbles behaved as solid particles.

Effect of Al(III) as an Activator for Adsorbing Colloid Flotation

Abstract The effect of Al(III) on adsorbing colloid flotation using Fe(OH)3 as the coprecipitant and sodium lauryl sulfate as the collector was studied, and the results of foam separation were compared with the zeta potential of the floc before and after Al(III) being added to the solution. It was found that when Al(III) is used as an activator, the zeta potential of the floc is more positive, which presumbly gives the floc a stronger affinity for anionic surfactant adsorption, resulting in better separation efficiency. The working range of pH for an effective separation is extended and good separation efficiency can be achieved at pH values closer to neutral with the aid of Al(III). Furthermore, the separation efficiency is significantly improved for solutions containing interfering ions, such as sulfate, by using Al(III) as an activator.

Adsorption of Anionic Surfactants on Cotton

Le mecanisme d'adsorption d'agents anioniques (laurylbenzenesulfonate ou laurylsulfate de sodium ou leurs melanges) sur le coton a ete etudie plus particulierement en fonction de la temperature; l'adsorption depend manifestement du processus de formation des micelles et des modifications des fibres dues a l'integration d'eau et aux changements de temperature

Influence of the nature of inorganic salts and their concentration on the simultaneous adsorption of cationic and anionic surfactants. Mixtures of dodecyltrimethylammonium salts with sodium hexylsulfate in the solutions containing the inorganic salt of ions common with the surfactants

The influence of the nature of the inorganic ions (Cl −, Br −, and ClO 4 −) and of NaBr concentration on the process of simultaneous adsorption of the respective dodecyltrimethylammonium salts (chloride, bromide, and perchlorate) and sodium hexylsulfate at the free surface of solutions containing NaCl, NaBr, or NaClO 4, respectively, was studied. Inorganic anions and hexylsulfate anions were found to adsorb competitively at the surface of solutions containing dodecyltrimethylammonium cations, at sufficiently high concentrations of inorganic salts. A lyotropic series of the anions Cl −<Br −∠ClO 4 − was also found for the process of coadsorption. Specific interactions between ClO 4 − and dodecyltrimethylammonium cations resulted in relatively high values of the free enthalpy of dodecyltrimethylammonium perchlorate adsorption and in significant asymmetry of the surface of solutions containing dodecyltrimethylammonium perchlorate and sodium hexylsulfate. Observed effects were described using the Butler-type isotherm of adsorption. Parameters of the adsorption were within the range of the component concentrations studied. The components were practically independent of concentrations which makes the Butler-type isotherms of adsorption especially convenient for pragmatic reasons.

Flotability and electrokinetic potential of insoluble salt-type minerals in solutions of indifferent electrolytes

This study showed that at sufficiently long adsorption times the adsorption of anionic surfactant was not influenced by the change of ζ-potential at the insoluble salt-type mineral-water interface resulting from concentration changes of an indifferent electrolyte. Thus, this group of minerals differs in its behaviour from that where the adsorption of a surfactant is controlled by H+ or OH− as potential-determining ions. This finding further confirms conclusions of our previous studies on adsorption mechanism of anionic surfactants on the surface of insoluble salt-type minerals [10].

Adsorption of surfactants on kaolinite: NaCl versus CaCl 2 salt effects

The adsorption of anionic ethoxy surfactants on kaolinite at room temperature has been studied as a function of pH and added electrolyte concentration (NaCl or CaCl 2). Adsorption from NaCl follows previous observations, with adsorption increasing with decreasing pH and increasing NaCl concentration. Adsorption from CaCl 2 shows much different behavior, with adsorption being high at acidic and basic pH's, and going through a shallow minimum at approximately pH = 8. Furthermore, adsorption is not dependent on CaCl 2 concentration above a certain minimum concentration. The observed behavior is interpreted in terms of the ability of Ca +2 to form a calcium-surfactant complex which can adsorb on the clay. Point of zero charge and surface area measurements were also made and support the above interpretation.

Preparation of cationic polymer surfaces by grafting polymerization

A cationic polymer surface with extensive capacity for adsorption of anionic surfactants was prepared by graft polymerization of vinyl pyridine onto a plasma-treated polypropylene surface. The nitrogen was quaternized in order to obtain the cationic sites. The concentration dependence of adsorption from high eletrolyte solution of the anionic surfactant was similar to the one a solid surface from solutions with no added electrolyte. The hydrophobic contribution to the adsorption was experienced at surfactant concentrations far below its critical micellization.

Surfactant interactions in poly(vinyl acetate) and poly(vinyl acetate–butyl acrylate) latexes

AbstractSaturation adsorption and penetration adsorption of several anionic surfactants at model poly(vinyl acetate–;acrylate) latex/water interfaces are described. The effects of molecular weight and structure of anionic surfactants, latex composition, and the presence of adsorbed layers on latex particles on penetration type surfactant interactions leading to the formation of solubilized polymer–surfactant complex and latex thickening are considered. In the case of saturation‐type adsorption of nonionic surfactants, surfactant adsorption at a vinyl acrylic latex/water interface is correlated satisfactorily with the polarity of polymer surface, in agreement with earlier surfactant adsorption studies.

Etude de l'adsorption de surfactants ioniques et non ioniques sur de la matière végétale carbonisée

The aim of this investigation was to assess the possible use of sulfuric lignins for the purification of industrial liquid wastes. The adsorption of anionic (SDS), cationic (CPC), and non-ionic (NPPO) surfactants on charred plant material was carried out under various pH and temperature conditions. Ionic and hydrophobic interactions are involved in the adsorption process. The analysis of the adsorption kinetics in aqueous and alcoholic media allowed the mode of adsorption to be characterized. The plot of the surfactant uptake against the square root of time led to the determination of the mode of diffusion. The effect of the chain length of alkylsulfates on their adsorption corroborated the involvement of hydrophobic interactions and could be correlated with the values of their cmc.

Light scattering method for the study of close range structure in coagulating dispersions of equal sized spherical particles

A light scattering method is proposed for studies of close range structure in flocs. This involves an analysis of the changes in the light scattered from coagulating dilute dispersions of equal sized spherical particles. From studies of initial coagulation behaviour, the size of particles, strictly their hard core interaction diameter, and the radial distribution function relating to particle contact can be determined. An approximate insight can be gained into average cumulative co-ordination numbers of particles in growing flocs.Studies of the rapid flocculation of polystyrene particles, in the joint presence of nonionic dextran flocculant and simple electrolyte coagulant, indicate close packed structure at low ionic strength and “liquid” floc arrangements at higher electrolyte concentrations. This suggests a weakening of the hard core interaction on addition of electrolyte which is likely to be a consequence of shielding of the electrostatic repulsion between the particles. Prolonged storage of the latex particles at 60°C or adsorption of anionic surfactant can lead to a strengthening of hard core interactions.The method can be used to size spherical particles of non-uniform refractive index and has been exploited in measurements of the thickness of adsorbed polymer and surfactant layers. It has indicated that storage at 60°C can increase the size of polystyrene particles (of unswollen diameter 207 nm) by 4 ± 2 nm.

Static and Dynamic Adsorption of Anionic and Nonionic Surfactants

Abstract The adsorption of commercial polyoxyethylene nonyl phenols and alkyl benzene sulfonates was studied by measuring the surfactant breakthrough from Berea cores. A rate model that reduces to a Langmuir-type isotherm at equilibrium represented these dynamic results and predicted successfully the equilibrium isotherms determined by static experiments.The ratios of both adsorption and desorption were determined and were observed to increase with the number of ethylene oxide groups. Adsorption of the nonionic surfactant appeared to be by hydrogen bonding and the amount adsorbed per unit of area was the same on a number of metal oxide substrates.Negligible adsorption was observed for sulfonates with an alkyl chain length of 9 or less. Introduction Surfactant adsorption is one of the important features governing the economic viability of chemical flooding processes. However, the adsorption on mineral oxide surfaces is only one of several possible mechanisms leading to surfactant losses.Other mechanisms include precipitation of surfactant in the presence of divalent ions, diffusion of surfactant into dead-end pores, and surfactant partitioning into the oil phase. It is necessary partitioning into the oil phase. It is necessary to minimize the losses by all mechanisms. The work reported here addresses the problem of surfactant adsorption; other mechanisms are not considered.There are a number of approaches that have the potential for minimizing adsorption. The most potential for minimizing adsorption. The most desirable surfactant is one that does not adsorb at all; however, such surfactants may not be effective oil-recovery agents. Sacrificial agents that adsorb in place of the surfactant can be used in a preflush or as a competitive additive to the surfactant slug, but effective agents have not yet been identified.Two aspects of the adsorption process are of interest the rate and the amount adsorbed. Both are examined here. The measurements include the dynamic adsorption of both anionic and nonionic surfactants in Berea cores that are initially filled with brine. The breakthrough curves are represented successfully using a model that accounts for the surface coverage. The rate expression reduces to a Langmuir-type isotherm. The shape of this curve has been verified by conducting static experiments.The study included both nonionic and anionic surfactants. These were not pure surfactants but, in general, they are well characterized. The anionic surfactants were studied because their behavior should-be representative of more complex mixtures such as the petroleum sulfonates that have been regarded as prime candidates for oil-recovery agents. These sulfonates are sensitive to divalent ions and many chemical slugs include quantities of nonionic surfactants to alleviate this difficulty to some extent. Therefore, this study included a systematic study of a particular class of nonionic surfactants. This study is the first to report rates of adsorption and desorption. From this information, the nature of the adsorption can be better understood. THEORY Michaels and Morelos have established that the adsorption of polyanions on kaolin occurs by hydrogen bonding. The specific sites at which this adsorption takes place were not defined. For the adsorption of surfactants, this mechanism can be represented as follows: ....................... (1) SPEJ p. 337

Influence of Solvents on Adsorption of Ionic Surfactants on Highly Dispersed Silicas

The adsorption of cationic and anionic surfactants on three hydrophilic silicas and one hydrophobic (methylated) colloidal silica was studied in the presence of organic solvents. Cationic surfactants (alkylpyridinium chlorides and alkyltrimethylammonium chlorides) are strongly bound by hydrophilic silicas in a weak polar solvent (CHCl3). While pyridinium and ammonium as the head group have no marked influence upon adsorption, the hydrocarbon chain length (in the range C4-C10) determines the surface areas occupied by adsorbed surfactant molecules. Homologs with longer hydrocarbon chains (C12-C18) all occupy equal areas in the saturated adsorption layer. Polar organic solvents (alcohols) reduce the adsorption of cationic surfactants on hydrophilic silicas. In the presence of dimethyl sulfoxide, no adsorption is observed. Maximum adsorption of dioctyl sodium sulfosuccinate is attained in the presence of carbon tetrachloride. Solvents with hydrogen-bonding abilities (dimethyl sulfoxide and dioxane) prevent adsorption of anionic surfactants (dioctyl sodium sulfosuccinate and sodium alkyl sulfates). It is suggested that the silanol groups on the surface, which are capable of hydrogen bonding and electrostatic interactions, are the active adsorption sites of the silica. If their number is reduced, the adsorption is diminished to the same extent.

Adsorption of Surfactants on Montmorillonite

AbstractSome authors have stated that anionic surfactants are not adsorbed by montmorillonite while others indicate very minor adsorption. Attempts to quantitatively determine the degree of adsorption have shown that certain problems exist which, unless recognized, will completely mask results. Some of these difficulties have been overcome but exact data have not yet been obtained. However, enough information has been gathered to prove that adsorption of anionic surfactants on montmorillonite is real and substantial. Reliable adsorption data for cationic and nonionic surfactants and one having both nonionic and anionic character have been obtained. It is indicated that 550 mg of these surfactants are adsorbed by 1 g of montmorillonite. X-ray diffraction data for complexes of all surfactants investigated confirm positive adsorption. However, the thickness of the adsorbed surfactant layers cannot always be quantitatively related to the amount of adsorbed surfactant.

Effect of cotton substrate characteristics upon surfactant adsorption

AbstractIt is shown that the reported differences in anionic surfactant adsorption on cotton can be largely attributed to the presence of variable amounts of natural wax on the fiber surface. High adsorption values with peaks near critical micelle concentration (cmc) result from surfactant adsorption on the wax surface. Wax‐free surfaces fail either to show the same high maxima or the same relative magnitude of adsorption. At surfactant cmc the adsorption relationship for waxy cotton (millimoles/g. of cotton) cationic: nonionic: anionic was roughly 66 to 17 to 74. For dewaxed cotton, this became 40 to 10 to nil.Confirming the findings of others, no adsorption by cotton of sodium tripolyphosphate occurs either with waxy or wax‐free cotton. Also addition of tripolyphosphate decreased the adsorption of several anionic surfactants.At concentrations greater than cmc and at sufficiently‐high solution temperature, anionic surfactants can solubilize cotton wax, leaving a less waxy substrate upon which adsorption is then reduced.

Rates of Adsorption of Sulphuric Acid on Wool in Presence of Surface‐active Agents

The rate of adsorption of sulphuric acid on wool is affected by surfactants. The effect of cationic and non‐ionic surfactants is small, but some anionic surfactants considerably decrease the rate of adsorption of acid, the effect depending on the concentration and on the critical micelle concentration of the agent. All agents are themselves adsorbed to various extents, and for anionic surfactants a correlation appears to exist between acid and surfactant adsorption. This correlation is no longer found if sodium sulphate is added, since this reduces the rate of adsorption of anionic surfactant, but increases the rate of adsorption of acid.

Studies on liquid films

The adsorption of mixtures from anionic and non-ionic surfactants on scheelite and calcite was tested with different physicochemical methods to determine the amounts adsorbed, the adsorption heats and the electrophoretic mobilities in dependence on surfactant concentration. The results show that in addition to the adsorption of anionic and non-ionic surfactants on the surface of the mineral, the formation of calcium surfactant salts in the mineral suspension should also be taken into account. The precipitation of calcium salts seems to be clearly reduced by the addition of non-ionic surfactants. As proved by flotation tests, the recovery and selectivity are thus increased with reduced collector dosage when the collector mixtures are used.