Concentration and recovery of halide complexes of aluminum subgroup metals by ionic flotation

The adsorption of chloride, bromide, and iodide complexes of aluminum, gallium, and indium on the liquid/gas interface activated by cetylpyridinium chloride, a cationic surfactant, was studied. The thermodynamic constants of the exchange of halide complexes with the chloride ion and the changes of thermodynamic functions for the ion-exchange adsorption on a floating air bubble surface activated by a cationic surfactant were calculated. The selectivity of exchange adsorption was found to grow with a decrease in the energy of the hydration of anionic complexes. The possibility of the selective flotation recovery of gallium and indium halide complexes from diluted solutions was shown.     

Rate of Bitumen Film Transfer from a Quartz Surface to an Air Bubble as Observed by Optical Microscopy

The rate of bitumen transfer from a bitumen‐coated quartz plate to a gas bubble surface in aqueous alkaline solutions was recorded photographically. During bitumen spreading, a bulk layer followed the formation of thin bitumen films (precursor films). The bulk layer spread at the bubble surface with a velocity of about one order of magnitude less than the velocity of the precursor film. The energy of activation for spreading of the bulk layer varied from about 66 to 123 kJ/mol depending on the stage of bitumen spreading but remained constant at about 105 kJ/mol for the precursor film. Results are discussed with respect to fundamental issues associated with flotation recovery of heavy oils.     

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.     

Solubilisation of dyes by surfactant micelles. Part 3; A spectroscopic study of azo dyes in surfactant solutions†

A spectroscopic study (UV–vis and adsorption) has been made of the interactions of select model azo dyes with a range of surfactant types or their mixtures both above and below their respective critical micelle concentrations. All surfactants inhibit adsorption of the dyes to cotton above their critical micelle concentrations due to incorporation in micelles. However, formation of 1;1 complexes between dyes and cationic or zwitterionic surfactants in sub‐micellar regions results in enhanced deposition on cotton. It is shown that attractive or repulsive electrostatic interactions play a key role in dye binding to micelles. Unusually, spectra of complexes formed between the dye and cationic surfactant are typical of those of the azo tautomeric form as opposed to the hydrazone form that is prevalent in aqueous media. Addition of anionic surfactant to micellar solutions of nonionic or zwitterionic surfactants results in successive displacement of dye from the respective micelles, i.e. binding is competitive.     

Adhesion of an Air Bubble to Quartz Surface in Aqueous Solution of Aliphatic Amine Hydrochloride

Measurements of the force of air bubble detachment from a quartz surface in aqueous solutions of decylamine hydrochloride (DAC1), dodecylamine hydrochloride (DDAC1) and tetradecylamine hydrochloride (TDAC1) were made in the concentration range from 0 to 200mg/dm³. At the same time, the instantaneous contact angle for the system quartz-air bubble-aqueous solution of aliphatic amine hydrochloride was photographed at the moment of detachment. Wetting contact angles for the system quartz-air bubble-aqueous solution of DDAC1 were also measured. On the basis of the measured values of the instantaneous angle and surface tension of the solutions studied, the changes of polar components of surface free energy of quartz/monolayer water film under the influence of adsorption of molecules of aliphatic amine hydrochloride (RAC1) from aqueous solution were calculated and compared with the literature data. Using these data, the force of air bubble detachment from the quartz surface in the presence of RAC1 was also calculated and compared with the measured force, obtaining a good agreement. From the studies and calculations it appears that a little addition of RAC1 to water considerably changes the stability of the system quartz-air bubble-solution, and that this change is first of all caused by reduction of a polar component of the surface free energy of quartz/monolayer water film as a result of adsorption of RAC1 molecules in the negative places of such a surface. As a result of RAC1 adsorption this surface becomes similar to that of paraffin.     

Adhesion of an Air Bubble to Quartz Surface in Aqueous Solution of Aliphatic Amine Hydrochloride

Measurements of the force of air bubble detachment from a quartz surface in aqueous solutions of decylamine hydrochloride (DAC1), dodecylamine hydrochloride (DDAC1) and tetradecylamine hydrochloride (TDAC1) were made in the concentration range from 0 to 200mg/dm³. At the same time, the instantaneous contact angle for the system quartz-air bubble-aqueous solution of aliphatic amine hydrochloride was photographed at the moment of detachment. Wetting contact angles for the system quartz-air bubble-aqueous solution of DDAC1 were also measured. On the basis of the measured values of the instantaneous angle and surface tension of the solutions studied, the changes of polar components of surface free energy of quartz/monolayer water film under the influence of adsorption of molecules of aliphatic amine hydrochloride (RAC1) from aqueous solution were calculated and compared with the literature data. Using these data, the force of air bubble detachment from the quartz surface in the presence of RAC1 was also calculated and compared with the measured force, obtaining a good agreement. From the studies and calculations it appears that a little addition of RAC1 to water considerably changes the stability of the system quartz-air bubble-solution, and that this change is first of all caused by reduction of a polar component of the surface free energy of quartz/monolayer water film as a result of adsorption of RAC1 molecules in the negative places of such a surface. As a result of RAC1 adsorption this surface becomes similar to that of paraffin.     

Surfactant-Induced Wettability Alteration of Oil-Wet Sandstone Surface: Mechanisms and Its Effect on Oil Recovery

Different analytical methods were utilized to investigate the mechanisms for wettability alteration of oil-wet sandstone surfaces induced by different surfactants and the effect of reservoir wettability on oil recovery. The cationic surfactant cetyltrimethylammonium bromide (CTAB) is more effective than the nonionic surfactant octylphenol ethoxylate (TX-100) and the anionic surfactant sodium laureth sulfate (POE(1)) in altering the wettability of oil-wet sandstone surfaces. The cationic surfactant CTAB was able to desorb negatively charged carboxylates of crude oil from the solid surface in an irreversible way by the formation of ion pairs. For the nonionic surfactant TX-100 and the anionic surfactant POE(1), the wettability of oil-wet sandstone surfaces is changed by the adsorption of surfactants on the solid surface. The different surfactants were added into water to vary the core surface wettability, while maintaining a constant interfacial tension. The more water-wet core showed a higher oil recovery by spontaneous imbibition. The neutral wetting micromodel showed the highest oil recovery by waterflooding and the oil-wet model showed the maximum residual oil saturation among all the models.     

Effect of Cationic Surfactant on the Adsorption of Arsenites onto Akaganeite Nanocrystals

Abstract

The current research focuses on removal of arsenite ions from aqueous solutions by a new adsorbent, surfactant modified akaganeite (Ak_m), prepared after the adsorption of the cationic surfactant, hexadecyl trimethyl ammonium bromide (N‐Cetyl‐N,N,N‐Trimethylammonium Bromide) onto akaganeite. The new adsorbent was investigated with Fourier transform infrared spectra and X‐ray photoelectron spectroscopy methods for a better understanding of the effects of surface properties on arsenite adsorption. Surfactant modified akaganeite was found to be an effective adsorbent for the removal of arsenite ions from aqueous systems. It presented a significantly higher arsenite adsorption capacity than the pure nanocrystalline akaganeite. Kinetics of adsorption obeys a second‐order rate equation. The maximum adsorption capacity was found to 328.3 mg g^?1 over a wide pH range significantly higher than those of other adsorbents reported.     

Wettability alteration and reducing water blockage in tight gas sandstone reservoirs using mixed cationic Gemini/nonionic fluorosurfactant mixtures

The unrecovered hydraulic fracturing fluid will invade the matrix and induce water blockage, creating formation damage and hindering the oil or gas production rate. First, the synergistic effect of cationic Gemini surfactant (MQAS) and nonionic fluorosurfactant (N-2821) mixtures on reducing the surface tension and wettability alteration was investigated in this paper. The critical micelle concentration (CMC) of the surfactant mixture is one or two orders of magnitude lower than that of N-2821 and MQAS, indicating that the MQAS/N-2821 mixtures exhibit an apparent synergistic effect in reducing surface tension. Moreover, the maximal contact angle of MQAS/N-2821 mixtures reached 83.55° at α_N-2821 = 0.5, and the total surfactant concentration of 1 × 10⁻⁴ mol/L due to the adsorption of surfactant. The adsorption mechanism of surfactants on the surface of quartz sand was then examined. The adsorption kinetics is consistent with the pseudo-second-order model at different surfactant concentrations, while the Freundlich model is suitable for describing the adsorption behavior of surfactants on the sandstone surface. This finding indicates that surfactant adsorption is multilayered. The MQAS/N-2821 surfactant mixtures have excellent surfactant activity due to the relationship of the capillary pressure to the surface tension, pore radius, and contact angle; thus, the addition of surfactant mixtures can reduce the liquid saturation effectively. Furthermore, the sequential imbibition experiments indicate that MQAS/N-2821 mixtures alter the wettability of the core plug, which results from the adsorption of surfactants. Compared with brine water, the MQAS/N-2821 mixtures decreased the liquid saturation and increased the permeability recovery ratios of the core plug.     

INFLUENCE OF MOLECULAR PROCESSES AT LIQUID INTERFACES ON DYNAMIC SURFACE TENSIONS AND WETTING KINETICS

The application of theories on the wetting kinetics of surfactant solutions requires accurate knowledge of the adsorption kinetics of the surfactant molecules at the involved interfaces. Studies on dynamic surface tensions give access to a quantitative understanding of the mechanisms governing this part of the complex wetting process. It is shown that besides the surface activity and the bulk concentration of a surfactant, the adsorption mechanism and the peculiarities of the interfacial dynamics play a significant role at the liquid-air interface. Due to interfacial processes, such as change in orientation or aggregation of molecules in the surface layer, differences in the adsorption time of more than one order of magnitude are observed.     

Synthesis and Surface Properties of a Novel Sodium 3‐(3‐Alkyloxy‐3‐oxopropoxy)‐3‐oxopropane‐1‐sulfonate at the Air–Water Interface

The present paper describes the synthesis and evaluation of surface properties of a novel series of anionic surfactant, namely sodium 3‐(3‐alkyloxy‐3‐oxopropoxy)‐3‐oxopropane‐1‐sulfonate with varying alkyl chain length (C8–C16). Synthesis involves initial formation of the 3‐alkyloxy‐3‐oxopropyl acrylate along with fatty acrylate during the direct esterification of fatty alcohol with acrylic acid in the presence of 0.5 % NaHSO₄ at 110 °C followed by sulfonation of the terminal double bond of the 3‐alkyloxy‐3‐oxopropyl acrylate. Synthesized compounds were evaluated for surface and thermodynamic properties such as critical micelle concentration (CMC), surface tension at CMC (γ_cmc), efficiency of surface adsorption (pC₂₀), surface excess (Γ_max), minimum area per molecule at the air–water interface (A_min), free energy of adsorption (?G°_ads), free energy of micellization (?G°_mic), wetting time, emulsifying properties, foaming power and calcium tolerance. Effect of chain length on CMC follows the classic trend, i.e. decrease in CMC with the increase in alkyl chain length. High pC₂₀ (>3) value indicates higher hydrophobic character of the surfactant. These surfactants showed very poor wetting time and calcium tolerance, but exhibited good emulsion stability and excellent foamability. Foaming power and foam stability of C14‐sulfonate were found to be the best among the studied compounds. Foam stability of C14‐sulfonate was also studied at different concentrations over time and excellent foam stability was obtained at a concentration of 0.075 %. Thus this novel class of surfactant may find applications as foam boosters in combination with other suitable surfactants.     

EFFECTS OF MASS TRANSFER ON THE THINNING AND RUPTURE OF A PLANE PARALLEL LIQUID FILM

The effects of mass transfer and physical properties upon the thinning and rupture of adraining plane parallel film are investigated.An equation is derived in which the thinning rate is afunction of bulk properties.surface properties(surface tension,surface viscosities,and the variationof surface tension with surface concentration),intermolecular forces(London-van der Waals forcesand electrostatic double layer forces),adsorption and surface diffusion coefficients,bubble size andfilm thickness.An estimation for the critical thickness at which a film rupture is carried out and thecoalescence time is obtained by integration to the critical thickness,The coalescence time is predictedas a function of bulk and surface properties,London-van der forces,adsorption and surfacediffusion coefficients,and bubble size.     

Adsorption of cationic/nonionic surfactant mixtures on polyester

Experiments were performed to characterize the adsorption of the cationic surfactant benzalkonium chloride (BZK) on polyester as well as measure the effect of the cationic surfactant on polyester surface charge. Additional studies were performed to examine the effect of adding nonionic surfactants on surface charge. In studies of adsorption of BZK on polyester, different behaviors were observed at pH values 6 and 10, with adsorption reaching a maximum at pH 10 but not at pH 6. In probing the zeta potential and isoelectric point (IEP) of polyester exposed to solutions composed of BZK (cationic surfactant) and an ethoxylated alcohol (nonionic surfactant), it was seen that the IEP could be shifted to higher pH levels by increasing the mole fraction of nonionic surfactant in a cationic/nonionic surfactant solution. A maximum in the IEP was obtained at a certain mole fraction for most cases. The shift in the IEP was hypothesized to be driven by increased deposition of the cationic, since the nonionic itself did not significantly change the IEP. The cooperative interactions between cationic and nonionic species were theorized to be driven not so much by attractive interactions, but other interactions, such as minimization of cationic charge repulsion.     

Influence of liquid surface tension (surfactants) on bubble formation at rigid and flexible orifices

The influence of liquid surface tension on the bubble formation from both rigid and flexible orifice has been investigated. The liquid phases under test are aqueous solutions with butanol or surfactants (cationic, non-ionic and anionic); static and dynamic measurements of liquid surface tension have been performed to characterise them. This study shows that the effect of surface tension on the bubbles generated cannot be analysed only in terms of the static surface tension, but also depends on whether the bubbles are generated from a rigid orifice or from a flexible orifice. The kinetics of adsorption and diffusion of the solute molecules towards the bubble interface have to be taken into account insofar as their time scales are comparable to those of the bubble formation phenomenon.     

Weight loss, polarization, electrochemical impedance spectroscopy, SEM and EDX studies of the corrosion inhibition of copper in aerated NaCl solutions

This work reports results of weight loss, potentiodynamic polarization and impedance measurements on the corrosion inhibition of copper in aerated non-stirred 3% NaCl solutions in the temperature range 15–65 °C using sodium oleate (SO) as an anionic surfactant inhibitor. These studies have shown that SO is a very good ”green”, mixed-type inhibitor. The inhibition process was attributed to the formation of an adsorbed film on the metal surface that protects the metal against corrosive agents. Scanning electron microscopy (SEM) and energy dispersion X-ray (EDX) observations of the electrode surface confirmed the existence of such an adsorbed film. The inhibition efficiency increases with increasing surfactant concentration and time of immersion, while it decreases with solution temperature. Maximum inhibition efficiency of the surfactant is observed at concentrations around its critical micellar concentration (CMC). The potential of zero charge (pzc) of copper was studied by ac impedance, and the mechanism of adsorption is discussed. The sigmoidal shape of the adsorption isotherm confirms the applicability of Frumkin’s equation to describe the adsorption process. Thermodynamic functions for the adsorption process were determined.     

Effects of Electrolyte Concentration on Surfactant Adsorption to a QCM Immersed in Surfactant + Electrolyte Solutions

Abstract

Surfactant adsorption from aqueous electrolyte solutions onto metal surfaces was characterized through the use of a Quartz Crystal Microbalance (QCM). The need for a better understanding of the surfactant adsorption process became apparent in previous studies by Morton et al., directed toward the development of a thermodynamically-based model of oil removal from metal surfaces. These modeling efforts utilized existing data on surfactant adsorption data, yet required the estimation of surfactant adsorption phenomena, such as the transition between monolayer adsorption and multi-layer adsorption and the location of the critical micelle concentration (CMC). Experimental techniques utilizing the quartz crystal microbalance (QCM) have been shown to be highly reliable for measuring slight changes, on the order of a nanogram, in the adsorption behavior of surfactants from aqueous solutions. The current study demonstrates that the addition of low concentrations (< 100 mM) of sodium chloride to aqueous solutions of ionic surfactant can have a significant effect on the adsorption of the surfactant to a gold surface. An analysis of the QCM measurements as well as a discussion of the effects of salt addition on various solution properties will be presented. Impacts of the current results to previously published work as well as potential applications will be discussed.     

Surfactant effect on production of monodispersed microspheres by microchannel emulsification method

Super-monodispersed oil-in-water (O/W) microspheres (MS) were produced using a microchannel (MC) emulsification technique. To investigate the effect of the surfactant on the behavior of the O/W-MS formation, the MS size and its distribution, various surfactants were used for the MC emulsification process. An MC plate with 8.9 μm equivalent diameter was employed. It was found that the super-monodispersed O/W-MS production depends on the type of surfactant used. When nonionic and anionic surfactants were used, supermonodispersed O/W-MS were produced, and the average droplet diameter was about 30 μm with a standard deviation less than 1 μm. For cationic surfactants, the super-monodispersed O/W-MS production was not successful, especially for the case where hydrophobic surfactant was dissolved in the oil phase. The results indicated that it is very important to maintain the hydrophilicity of the MC surface during the MC emulsification process. It is considered that the hydrophilic group of the anionic and nonionic surfactant was repulsed from the negatively charged MC surface so that the hydrophilicity of the MC surface was maintained. Otherwise, adsorption of the positively charged group of the cationic surfactant occurred on the MC surface which improved wetting of the MC surface and deteriorated the MC emulsification process. The analysis was supported by contact angle measurement.     

Adsorption,Electrokinetic and Stabilizing Properties of the Guar Gum/Surfactant/Alumina System

The adsorption of non‐ionic polysaccharide guar gum (GG) in the presence of surfactants (anionic SDS, non‐ionic TX‐100, cationic CTAB and their equimolar mixtures) from their NaCl solutions onto an alumina surface (Al₂O₃) was studied spectrophotometrically. This study is important in light of the many disagreements concerning the structure and behaviour of mixtures containing polymers and surfactants at the surface of an adsorbent. The presence of surfactant caused an increase in the GG adsorption in all studied systems as a consequence of the formation of complexes. Among the single surfactants the highest increase in the GG adsorption was observed in the presence of CTAB. However, the usage of mixtures of the surfactants caused a much more effective increase in the GG adsorption on the alumina surface because of the synergistic effect of the surfactants. In order to get some information on the structure of the electrical double layer (edl), the surface charge density of alumina was determined and zeta potential measurements were conducted. The obtained data showed that the adsorption of GG or GG/surfactant complexes on the metal oxide surface strongly influences a diffused part of the edl, whereas a compact part of the edl is not affected. The colloidal stability of the alumina suspensions was measured in the presence and absence of GG and surfactants. It was found that GG and the mixtures of GG and surfactants can improve the stability of the suspensions.     

Electropolymerization of ethylene dioxythiophene (EDOT) in micellar aqueous solutions studied by electrochemical quartz crystal microbalance and surface plasmon resonance

Electropolymerization of 3,4-ethylene dioxythiophene (EDOT) on gold electrodes was studied in situ by means of an electrochemical quartz crystal microbalance (EQCM) and by surface plasmon resonance spectroscopy (SPR) using aqueous micellar monomer solutions. Electrodeposition from micellar solutions performed by cyclic voltammetry (CV) displayed an enhanced rate as compared to surfactant concentrations lower than the critical micelle concentration (cmc) or in surfactant-free monomer solutions. EQCM data indicate the occurrence of additional film growth during the reductive scan to large negative potentials which does not occur in electropolymerization experiments using potentiostatic pulses or cyclovoltammetric cycles with less negative potential scans. Our results further suggest that in the case of the anionic surfactant the oxidation potential of the monomer is lowered even at surfactant concentrations below the cmc. AFM investigations show a slightly enhanced roughness of the films obtained from micellar monomer solutions.