Kirk Herbert Raney

Solubilization-emulsification mechanisms of detergency

Abstract The removal of oily soils from fabrics having high contents of polyester or other synthetic materials occurs largely by a solubilization-emulsification mechanism. A systematic investigation of this mechanism has been conducted during the past several years and is reviewed here. The research has utilized a variety of oily soils containing hydrocarbons, triglycerides, and long-chain alcohols and fatty acids and has included the determination of equilibrium phase behavior, the observation of dynamic behavior which occurs when surfactant-water mixtures contact oily soils, and measurement of soil removal from polyester-cotton fabrics. In most cases, pure surfactants and oils have been used for simplicity, but data showing the applicability of major conclusions to systems containing commercial surfactants are presented. Because typical anionic surfactants are too hydrophilic to achieve the desired phase behavior, the work has employed non-ionic surfactants and mixtures of non-ionics and anionics. One major conclusion is that maximum soil removal usually does not occur when the soil is solubilized into an ordinary micellar solution, but instead when it is incorporated into an intermediate phase such as a microemulsion or liquid crystal that develops during the washing process at the interface between the soil and washing bath. Indeed, for hydrocarbon and triglyceride soils, the washing bath is itself a dispersion of a surfactant-rich liquid or liquid crystalline phase in water for conditions of optimum detergency, i.e. the temperature of the surfactant solution is above — sometimes far above — its cloud point temperature.

Mechanism for defoaming by oils and calcium soap in aqueous systems.

The effect of oils, hardness, and calcium soap on foam stability of aqueous solutions of commercial surfactants was investigated. For conditions where negligible calcium soap was formed, stability of foams made with 0.1 wt% solutions of a seven-EO alcohol ethoxylate containing dispersed drops of n-hexadecane, triolein, or mixtures of these oils with small amounts of oleic acid could be understood in terms of entry, spreading, and bridging coefficients, i.e., ESB analysis. However, foams made from solutions containing 0.01 wt% of three-EO alcohol ethoxysulfate sodium salt and the same dispersed oils were frequently more stable than expected based on ESB analysis, reflecting that repulsion due to overlap of electrical double layers in the asymmetric oil-water-air film made oil entry into the air-water interface more difficult than the theory predicts. When calcium soap was formed in situ by the reaction of fatty acids in the oil with calcium, solid soap particles were observed at the surfaces of the oil drops. The combination of oil and calcium soap produced a synergistic effect facilitating the well-known bridging instability of foam films or Plateau borders and producing a substantial defoaming effect. A possible mechanism of instability involving increases in disjoining pressure at locations where small soap particles approach the air-water interface is discussed. For both surfactants with the triolein-oleic acid mixtures, calculated entry and bridging coefficients for conditions when calcium soap formed were positive shortly after foam generation but negative at equilibrium. These results are consistent with the experimental observation that most defoaming action occurred shortly after foam generation rather than at later times.

The effect of polar soil components on the phase inversion temperature and optimum detergency conditions

Previously reported results have shown that optimum removal of a hydrocarbon soil from polyester/cotton fabric occurs above the cloud point at the phase inversion temperature (PIT) of nonionic surfactant/water/soil systems. Through comparison of phase behavior measurements to radiotracer detergency studies using model sebum soils, i.e., cetane/oleyl alcohol and cetane/oleic acid blends, the relevance of the PIT for removal of nonpolar/polar soil mixtures has also been demonstrated. For these soils, the PIT is typically below the cloud point, and the highest level of soil removal is found between the PIT and cloud point rather than only at the PIT. This relatively temperature-insensitive soil removal is attributed to the preferential solubilization of polar soil components which continually changes the composition of the residual soil during the washing cycle. These findings explain the long-observed results that 4- to 5-EO alcohol ethoxylates are preferred for the removal of nonpolar soils while 6- to 9-EO ethoxylates are the more effective surfactants for sebum soils.

Optimization of nonionic/anionic surfactant blends for enhanced oily soil removal

Previously reported results for alcohol ethoxylate surfactants have shown that optimum removal of both nonpolar and sebum- like liquid soils from polyester/cotton fabric occurs at the phase inversion temperature (PIT) of the surfactant- water- soil system. A similar correlation between phase inversion and optimum detergency has been identified for detergent systems containing mixtures of nonionic and anionic surfactants such as alcohol ethoxylates and alcohol ethoxysulfates. Experimental techniques other than direct detergency studies are described which allow determination of the optimum nonionic/ anionic surfactant ratio for removal of a particular soil at a specified temperature. In addition, implications of these results for development of temperature- insensitive detergent formulations containing alcohol ethoxylates are discussed.

A novel dianionic surfactant from the reaction of C14-alkenylsuccinic anhydride with sodium isethionate

A novel derivative of alkenylsuccinic anhydride has been developed. When the anhydride is opened with sodium isethionate, a difunctional surfactant, alkenyl carboxysulfonate (ACS), is produced. This product has a unique combination of properties: moderate foaming, effective detergency, as well as the capability to function as a hydrotrope and as a co-builder in formulated cleaning systems. This paper briefly reviews some past studies with ACS. The utility of ACS in hard-surface cleaning is also examined, especially the capacity of this molecule to act both as a low-streaking surfactant and a hydrotrope. This combined function should allow formulators to diminish or eliminate volatile solvents in a variety of cleaning products. ACS has shown merit as an agent to reduce soil redeposition in three different heavy-duty liquid formulations. Additionally, heavy-duty liquid detergents containing ACS can be formulated to high surfactant and organic builder levels.

Impact of phase behavior on aquatic toxicity testing of alcohol ethoxylates

Abstract Due to the large quantity of alcohol ethoxylate surfactants used in both household and institutional cleaning applications and their discharge down-the-drain after use, the toxicity properties of alcohol ethoxylates (AE) in aqueous environments have received considerable attention. However, the potential effects of surfactant phase behavior have often not been considered when developing test procedures for ecotoxicity and interpreting test results. These effects are particularly important for studies of sparingly-soluble commercial AEs which are mixtures containing a broad distribution of ethoxylated species and alkyl chain lengths. In this regard, it has been determined that stock solutions containing 0.1–5 wt% AE should be prepared and stored in a single-phase micellar regime, i.e. between a lower crystallization temperature and the cloud point, to ensure that the test surfactant is dosed accurately. Turbidity and videomicroscopy measurements have been used to determine this temperature regime for a variety of ethoxylates. Also, the potential for phase separation of insoluble components as a broad distribution AE is diluted to below its critical micelle concentration has been examined using a variety of physical and analytical chemistry methods.

Prediction and Experimental Measurements of Water-in-Oil Emulsion Viscosities During Alkaline/Surfactant Injections

Oil production is generally a complicated multiphase flow inside pipelines, with possible water-in-oil (W/O) emulsions present with other usual phases such as free water and free oil. The W/O emulsions formed can present significant hurdles in production facilities for pumping fluids and during pipeline transport. It is well known that high shear rates provided by pumps, chokes, or valves result in stable emulsion behavior for a field in primary production. Several field tests are under way to test the potential of surfactant flooding as a tertiary-recovery mechanism. The effect of addition of surfactants on the emulsion rheology of production fluids, as in alkaline/ surfactant/polymer (ASP) flooding, is not very well understood. This understanding of W/O-emulsion rheology in ASP-injection oil recovery is essential for design of pumps and pipelines as well as for handling flow-assurance issues. In this paper, we report results from experiments as well as modeling of W/O-emulsion rheology that can form during ASP injections. We focus here only on the alkaline/surfactant (AS) part of these injections in order to clearly understand the impact of surfactants, removing the uncertainities that come with large rheology changes with polymer addition. The effect of surfactants on the rheology of W/O emulsions was studied by making two different types of emulsions: (1) native-brine W/O emulsions without surfactants to provide a baseline and (2) brine W/O emulsions with surfactants used in ASP injections. This way, the impact of ASP injections on emulsion rheology can easily be quantified. A new correlation is developed, based on in-house historical experimental data, to describe rheology of emulsions without surfactants. This correlation should assist in managing the uncertainties that come from extrapolating emulsion rheology measured in the laboratory to actual field conditions. Further, to understand the effect of ASP injections, new experimental measurements were made by adding surfactants to brine solutions. The addition of surfactants resulted in different rheology as compared with emulsions formed by brine solutions. These differences have been attributed to the W/O interfacial tension (IFT), and IFT was added to modify the original correlation. To our knowledge, this is the first study that explicitly relates emulsion rheology with IFT.

Ammonia as Alkali for ASP Floods – Comparison to Sodium Carbonate

Ammonia is logistically preferred over sodium carbonate for alkaline-surfactant-polymer enhanced oil recovery projects (ASP) due to its low molar mass and the possibility for it to be delivered as a liquid. On an offshore platform space and weight savings can be the determining factor in deciding whether an ASP project is feasible. Logistics may also be critical in determining the economic feasibility of projects in remote locations. Ammonia as alkali together with a surfactant blend of alkylpropoxy sulfate – internal olefin sulfonate (APS/IOS) functions as an effective alkali. Surfactant adsorption is low and oil recovery in core floods is high. Static adsorption tests show that low surfactant adsorption is attained at pH > 9, a condition that ammonia satisfies at low solution concentration. It is expected that ammonia has a performance deficiency relative to sodium carbonate in that it does not precipitate calcium from solution. Calcium accumulation in the ammonia ASP solution will occur due to ion exchange from clays. The high oil recovery for ammonia and the calcium accumulation in ASP and SP core floods with APS-IOS blends shows that this surfactant system is effective and calcium-tolerant. Also, phase behavior and IFT measurements suggest that APS/IOS blends remain effective in the presence of calcium. EO/PO sulfates (such as the employed APS) are known commercially available, calcium-tolerant surfactants. However, due to hydrolysis sulfate-type surfactants are suitable for use only in lower temperature reservoirs. Very different behavior was noticed for phase behavior measurements with calcium intolerant surfactants such as alkyl benzene sulfonates (ABS) and internal olefin sulfonates (IOS). In this case calcium addition results in a very high IFT and complete separation of oil and brine. Presumably this will result in low oil recovery. A preferred approach for ASP offshore with divalent ion intolerant surfactants may be the use of a hybrid alkali system combining the attributes of sodium carbonate and ammonia. The concept is to supply the bulk of the alkalinity for an ASP flood by ammonia with all the inherent logistical advantages. A minor quantity of sodium carbonate is added to the formulation to specifically precipitate calcium ions.