Nonionic surfactants, development

A nonionic surfactant developed primarily for use in agricultural pesticides. This surfactant is an EPA compliant version of SURFYNOL TG surfactant. It is used as a low foaming agent in wettable powders and liquid concentrates and as a wetting agent for rapid dispersion of concentrates in water. 

Motomizu, S., M. Oshima, Y. Hosoi, Spectrophotometric determination of cationic and anionic surfactants with anionic dyes in the presence of nonionic surfactants development of batch and flow injection methods, Mikrochim. Acta, 1992,106,61-1A. 

Iodine is extensively used in a variety of forms as both an antiseptic and a disinfectant. lodophors, usually nonionic surfactants (qv) complexed with iodine, were developed for more readily usable iodine-based antiseptics and disinfectants. These are used as disinfectants in dairies, laboratories, and food processing (qv) plants, and for sanitation of dishes in restaurants. The reaction product of lanolin and iodine shows utiHty as a germicide (149). 

A detergent that is compatible with the remover formula must be developed for water rinse removers. Anionic or nonionic surfactants should be selected, depending on the pH and intended application of the remover. 

In the 1990s, the thmst of surfactant flooding work has been to develop surfactants which provide low interfacial tensions in saline media, particularly seawater require less cosurfactant are effective at low concentrations and exhibit lower adsorption on rock. Nonionic surfactants such as alcohol ethoxylates, alkylphenol ethoxylates (215) and propoxylates (216), and alcohol propoxylates (216) have been evaluated for this appHcation. More recently, anionic surfactants have been used (216—230). 

The most commonly used emulsifiers are sodium, potassium, or ammonium salts of oleic acid, stearic acid, or rosin acids, or disproportionate rosin acids, either singly or in mixture. An aLkylsulfate or aLkylarenesulfonate can also be used or be present as a stabilizer. A useful stabilizer of this class is the condensation product of formaldehyde with the sodium salt of P-naphthalenesulfonic acid. AH these primary emulsifiers and stabilizers are anionic and on adsorption they confer a negative charge to the polymer particles. Latices stabilized with cationic or nonionic surfactants have been developed for special apphcations. Despite the high concentration of emulsifiers in most synthetic latices, only a small proportion is present in the aqueous phase nearly all of it is adsorbed on the polymer particles. 

An alternate approach for biomolecule recover is to employ degradable surfactants [157]. A series of nonionic surfactants has been synthesized that contain the acidic pH-degradable cyclic ketal linkage [153]. These surfactants readily form w/o-MEs when at neutral pH or higher but, the surfactants readily degrade at moderately low pH (ca. 5), releasing the encapsulated aqueous phase and its constituents. Work is ongoing to develop these surfactants in w/o-ME protein extraction processes [153]. 

Cloud Points The influence of added NaCl on the observed cloud points of 1% W/V solutions of the four nonionic surfactants under observation are given in Figure 1. Approximately linear correlations were observed as the aqueous NaCl level was increased, with negative coefficients recorded between 0.22 - 0.3 K.g "1dm3. Higher loadings of surfactant were found to increase the cloud point. It was observed also that the inclusion of small quantities of oils to surfactant solutions could either elevate or depress the cloud point. The significance of this fact will be developed later. 

In the remainder of this article, discussion of surfactant dissolution mechanisms and rates proceeds from the simplest case of pure nonionic surfactants to nonionic surfactant mixtures, mixtures of nonionics with anionics, and finally to development of myehnic figures during dissolution, with emphasis on studies in one anionic surfactant/water system. Not considered here are studies of rates of transformation between individual phases or aggregate structures in surfactant systems, e.g., between micelles and vesicles. Reviews of these phenomena, which include some of the information summarized below, have been given elsewhere [7,15,29]. 

The deviations from the Szyszkowski-Langmuir adsorption theory have led to the proposal of a munber of models for the equihbrium adsorption of surfactants at the gas-Uquid interface. The aim of this paper is to critically analyze the theories and assess their applicabihty to the adsorption of both ionic and nonionic surfactants at the gas-hquid interface. The thermodynamic approach of Butler [14] and the Lucassen-Reynders dividing surface [15] will be used to describe the adsorption layer state and adsorption isotherm as a function of partial molecular area for adsorbed nonionic surfactants. The traditional approach with the Gibbs dividing surface and Gibbs adsorption isotherm, and the Gouy-Chapman electrical double layer electrostatics will be used to describe the adsorption of ionic surfactants and ionic-nonionic surfactant mixtures. The fimdamental modeling of the adsorption processes and the molecular interactions in the adsorption layers will be developed to predict the parameters of the proposed models and improve the adsorption models for ionic surfactants. Finally, experimental data for surface tension will be used to validate the proposed adsorption models. 

The mass action model (MAM) for binary ionic or nonionic surfactants and the pseudo-phase separation model (PSM) which were developed earlier (I EC Fundamentals 1983, 22, 230 J. Phys. Chem. 1984, 88, 1642) have been extended. The new models include a micelle aggregation number and counterion binding parameter which depend on the mixed micelle composition. Thus, the models can describe mixtures of ionic/nonionic surfactants more realistically. These models generally predict no azeotropic micellization. For the PSM, calculated mixed erne s and especially monomer concentrations can differ significantly from those of the previous models. The results are used to estimate the Redlich-Kister parameters of monomer mixing in the mixed micelles from data on mixed erne s of Lange and Beck (1973), Funasaki and Hada (1979), and others. 

Many models have appeared in the literature describing interactions of surfactants in mixed micelles (1-14). For nonionic surfactants mixing nonideally, the key references up to 1984 have been recently summarized (15). Comparatively few models have been developed for ionic surfactants (5,6,10-12) and fewer models which acknowledge ionic/nonionic interactions are available (5-7). Since many practical surfactant mixtures involve ionic and nonionic surfactants which interact with each other and with added salts, it is important to develop explicit ionic/nonionic models. 

The purpose of this paper is to develop realistic specific models of mixed micellization which (i) can describe properties of ionic/nonionic surfactant mixtures and effects of salt (ii) lead to tractable calculations and (iii) can be used for extracting information on micelle mixing and monomer concentrations from the limited experimental data which are usually... 

The purpose of this paper will be to develop a generalized treatment extending the earlier mixed micelle model (I4) to nonideal mixed surfactant monolayers in micellar systems. In this work, a thermodynamic model for nonionic surfactant mixtures is developed which can also be applied empirically to mixtures containing ionic surfactants. The form of the model is designed to allow for future generalization to multiple components, other interfaces and the treatment of contact angles. The use of the pseudo-phase separation approach and regular solution approximation are dictated by the requirement that the model be sufficiently tractable to be applied in realistic situations of interest. 

To increase the usefulness of bioremediation as an effective field remedial tool, significant investments have been made towards the development of means to remove sorbed PAHs, attack sources of NAPL, and subsequently increase the aqueous solubility/bioavailability, and thus the biodegradability, of targeted compounds. To date, one of the most effective ways to accomplish these tasks involves the use of surface active agents (i.e., surfactants). A variety of synthetic surfactants have been shown effective in increasing the bioavailability of PAHs and other hydrophobic contaminants (Kile Chiou, 1989, 1990 Edwards et al., 1991 Liu et al., 1991). Although the solubilization process is not completely understood, these studies showed that a variety of ionic and nonionic surfactants could significantly increase the water solubility of monitored chemicals. 

Drug A is a large, peptide-like molecule (MW 700 g/mol) and is highly lipophilic and poorly water soluble. It is a BCS Class II drugs. Its oral bioavailability in capsules and conventional tablet formulations is low, yielding practically undetected blood levels. A novel lipid formulation containing a solvent, a high HLB nonionic surfactant, and a fatty acid were developed with sufLcient oral bioavailability for use in the clinic. 

Florence (1983) provide a comprehensive reference for the use of surfactants in drug formulation development. The treatment by Florence (1981) of drug solubilization in surfactant systems is more focused on the question at hand and provides a clear description of surfactant behavior and solubilization in conventional hydrocarbon-based surfactants, especially nonionic surfactants. This chapter will discuss the conventional surfactant micelles in general as well as update the reader on recent practical/commercial solubilization applications utilizing surfactants. Other uses of surfactants as wetting agents, emulsiLers, and surface modiLers, and for other pharmaceutical applications are nc emphasized. Readers can refer to other chapters in this book for details on these uses of surfactant Polymeric surfactant micelles will be discussed in Chapter 13, Micellization and Drug Solubility Enhancement Part II Polymeric Micelles. 

Several models have been developed to interpret micellar behavior (Mukerjee, 1967 Lieberman et al., 1996). Two models, the mass-action and phase-separation models are described here in mor detail. In the mass-action model, micelles are in equilibrium with the unassociated surfactant or monomer. For nonionic surfactants with an aggregation numb itbfe mass-action model predicts thatn molecules of monomeric nonionized surfactaStajeact to form a micelleM ... 

---