The “Hard” and “Soft” surfactant profile of israel municipal wastewaters

A study of mapping and field monitoring of Israel’s municipal sewage wastewaters in respect to the content, distribution and the initial nonbiodegradable-biodegradable ratio of surfactants in them has been undertaken over the central and northern parts of the country under in vivo conditions. Typical concentrations of nonionics (mainly “hard” alkylphenol-based ethoxylates) and anionics (mainly the “soft” LABS) in influents were found to be within the range of 1.1–2.2 and 9.6–10.6 mg/liter respectively. In (treated) effluents, the corresponding concentrations are 0.3–0.45 and 0.3–4.3 mg/liter. The above is in accordance with current world trends following the switch to biodegradable surfactants. However, the concentrations of nonionic surfactants in the municipal wastewaters are surprisingly low in view of the preferred consumption of “hard” nonionic surfactants in the local market. It is concluded that 20–40% of all nonionic surfactants discharged into municipal sewage, additional amounts of their metabolites and some of the anionic surfactants, too, find their way into receiving waters, because they resist substantial removal via only primary and secondary treatment.     

Novel general procedure for the preparation of homogeneous nonionic surfactants

Homogeneous nonionic surfactants were produced by the ethoxylation of a selected unit of a homolog series. These particular products are of use for the analysis of nonionics and for the determination of surface characteristics. A new general method for the synthesis of homogeneous nonionic surfactants is described. Ethylene glycol monobenzyl ether was repeatedly reacted in Williamson synthesis (or esterified with acid chlorides in the first step), followed by hydrogenolysis with alkyl- or aralkyl alcohols, phenols, carboxylic acids, and amines. Homogeneous nonionics can be synthesized by this method, whereas the conventionally produced ones are usually inhomogeneous.     

Influence of hydrophobe type and extent of branching on environmental response factors of nonionic surfactants

A number of ethoxylated nonionic surfactants differing in hydrophobe branching and chainlengths have been evaluated for environmental responses. Screening biodegradation tests show that those nonionics having more than one methyl group per hydrophobe degrade considerably slower than those having less extensive branching. Continuous flow-through activated sludge tests, simulating actual waste treatment, show that the more highly branched nonionics biodegrade more slowly and less extensively than those with less hydrophobe branching. In addition, treated effluents originating from influents containing the more highly branched nonionics tend to be more surface active and more toxic to aquatic species than those originating from influents containing surfactants with less hydrophobe branching. Under conditions simulating plant stress, such as high surfactant concentrations in the influent or low temperature, biodegradation of the highly branched nonionics was considerably less extensive, while biodegradation of the linear nonionics was not affected to any measurable degree compared to more normal operating conditions. Presented at the 81st American Oil Chemists’ Society Annual Meeting, April 22–26, 1990, Baltimore, Maryland.     

Analysis of mixtures of ionic and nonionic surface-active agents. Separation and recovery of components by batch ion exchange

Mixtures of anionic and nonionic surfactants or cationic and nonionic surfactants can be separated by stirting an aqueous solution of the mixture with a small amount of a strong anion exchange or strong cation exchange resin, respectively. The resin-ionic surfactant complex is removed by filtration and washed; the nonionics are recovered from the filtrate and washings. By suitable treatment the ionic surfactants can be removed selectively from the resin. In the case of anionic surfactants, soaps, alkyl sulfates, and alkylaryl sulfonates can successively be removed from the resin; with cationics, nonquaternary and quaternary surfactants can be selectively removed. Results obtained with various mixtures of surface active agents are discussed. Presented at the 51st fall meeting, American Oil Chemists’ Society, New York, October 17–19, 1960.     

The status of biodegradability testing of nonionic surfactants

A wide range of nonionic surfactants was studied in an extensive inter-laboratory biodegradability testing program carried out by member companies of The Soap and Detergent Association over a three year period. The objectives were to determine the biodegradability of a variety of nonionic surfactants, and to develop a reliable laboratory scale test method which could be used to evaluate the biodegradability of new candidate materials. The results of this research and testing confirm that the primary and secondary alcohol ethoxylates, the alkyl alkanolamides, and the alkyl amine oxides are all highly biodegradable. These materials represent the important classes of nonionics used in household and institutional synthetic detergents. The removal of these materials under conditions of normal secondary wastewater treatment can be anticipated. The diversity of structures represented in the complete nonionic surfactant spectrum, and the problems of residue analysis imposed serious obstacles in the development of a single standard laboratory procedure which will correlate well with the limited field data presently available. The objective of establishing a standard test for all nonionics was not achieved. Residues of nonionic surfactants from household and institutional synthetic detergents do not appear to contribute to esthetic water pollution or to interfere with waste treatment processes. A variety of biodegradability assessment procedures, applicable to specific nonionics or nonionic groups are currently available and should assure that their residues will not adversely affect the quality of receiving waters. The Subcommittee plans to maintain a program for continued research in nonionic biodegradability testing. Prepared under the auspices of The Subcommittee on Biodegradation Test Methods of The Soap and Detergent Association.     

Chemie und Technologie der Herstellung nichtionischer Tenside

Chemistry and Technology of Manufacture of Non-Ionic Surfactants Classification of surfactants and the historical development of nonionics are outlined. A great deal of data reveals the increase in economical significance of nonionic surfactants compared to other groups of washing agents including soaps. The supply of raw materials is guranteed for the production of nonionics, which assures a positive trend of future development for this group of surfactants. Relationship between chemical constitution of nonionics and their biological degradability is described briefly, which is followed by chemistry and synthesis of nonionics. Special reference is made to catalytic oxethylation and the properties of oxethylated products, such as solubility and turbidity point in aqueous solutions. One section deals with the synthesis of uniform and chemically defined nonionics which are important model substances. The last section describes the technical production of some common types of nonionics.     

Performance and properties of nonionic surfactants from linear secondary alcohols

Surfactants based on the linear secondary alcohols provide a new source of biodegradable detergents. The nonionic surfactants of these alcohols are discussed in relationship to their surfactant properties and performance in detergent formulations. The performance properties in detergent formulations are defined by the results of detergency and foam stability tests. The surfactant properties presented are viscosity, surface tension, wetting and alkaline color stability. The above properties of the nonionic surfactants from the linear secondary alcohols have been compared to the properties of the less degradable nonylphenol nonionics and to the nonionic surfactants from the linear alkylphenol, oxo alcohol and Ziegler alcohol hydrophobes.     

Effect of Selected Nonionic Surfactants on the Activated Sludge Morphology and Activity in a Batch System

In this study, two nonionic surfactants, one alcohol ethoxylate (AE) and one alkylphenol ethoxylate (APE) were investigated with regard to their influence on the morphology of activated sludge flocs, microbial activity and wastewater treatment efficiency in a laboratory batch system. The experiments were carried out for a range of nonionic surfactants concentrations in wastewater from 5 to 500 mg L⁻¹. Additionally, these results were compared to the data obtained in previous experiments on anionics and performed under the same conditions. Both nonionics tested caused a decrease in the size of activated sludge flocs but they did not affect the shape of the flocs. The circularity index and convexity of flocs remained similar to the control run, containing no surfactant. The presence of nonionic surfactants within the tested concentrations range caused a decrease in biomass activity. In spite of morphological changes of activated sludge flocs and a decrease in microbial activity, only higher concentrations of nonionics in wastewater starting with the level of 50 mg L⁻¹ can induce pinpoint flocs and decrease wastewater treatment efficiency. APE showed a stronger impact on the decrease in floc size and microbial activity than alcohol ethoxylate did. APE was also more difficult to biodegrade than AE. Comparing the efficiency of wastewater treatment (in terms of COD removal) in the presence of nonionic and anionic surfactants at the same concentration of 50 mg L⁻¹, the degree of organic pollutant removal was found to be higher by about 10% for anionics than for nonionics.

Some Surface Properties of Polysorbates and Cetyl Trimethyl Ammonium Bromine Mixed Systems

Mixed surfactant solutions consisting of cationic/nonionic surfactants were prepared in different compositions of the components in aqueous solution in order to determine the surface properties. The critical micelle concentration (CMC) of aqueous solutions of the individual surfactants cetyl trimethyl ammonium bromide (CTAB) and polysorbate nonionics, and their mixtures are determined at different proportions. The results show that there is synergistic behavior in mixtures at higher mole fraction of nonionic surfactant. The effect of the alkyl chain on the CMC is also determined.     

Correlation between spray cleaning detergency and dynamic surface tension of nonionic surfactants

The role of temperature and dynamic surface tension (DST) in spray-cleaning processes in industrial applications was investigated with nonionic surfactants. Relative performance data for various ethoxylates (derived from primary alcohols or nonylphenol) were obtained by a spray-cleaning method. The spray-cleaning method was developed to screen and identify optimum surfactants, formulations, and conditions for spray-cleaning applications. It is introduced here as a means to mimic spray-cleaning processes by (timed) spraying of a cleaner solution under pressure onto a soiled substrate. Results of this investigation indicated that temperature and DST play major roles in the soil-removal process. Observed temperature trends are typical of nonionic surfactants’ clouding phenomena. Optimum cleaning was observed at specific temperatures. Also, nonionics with shorter hydrophobes exhibited the best detergency. Spray-cleaning detergency was compared to the DST because spray cleaning involves a dynamic interfacial process. New interfaces are constantly being created. Results showed that the surfactants with the lowest DST exhibited the best soil removal. This correlation can allow for a fast, cost-effective means for screening potential candidates and reducing development time for industrial spray-cleaning applications. Presented at the 85th Annual AOCS Meeting, May 8–12, 1994, Atlanta, Georgia.     

Selecting the optimal linear alcohol ethoxylate for enhanced oily soil removal

Use of nonionic surfactants in detergent products has become increasingly popular because of their tolerance to hardness ions and their effect on lowering the critical micelle concentration of anionics. Their performance as detergents, however, is very sensitive to changes in temperature and electrolyte concentration, which need to be carefully controlled in order to ensure that phase inversion conditions prevail. For a fixed temperature in an application, the only variables available for optimizing the performance of a system containing nonionics are: the type of nonionic, and the concentrations of electrolytes and anionics. Based on the mutual interactions of these ingredients in mixed systems, we have devised some guidelines for selection of the optimal ethylene oxide (FO) chain length in lauryl alcohol ethoxylate type of nonionics for a range of electrolytes and anionic surfactant concentrations. For any given concentration of electrolytes (sodium carbonate and sodium tripolyphosphate), anionic (sodium linear alkyl benzene sulfonate) and nonionic, the detergency of synthetic sebum from blended polyester/cotton fabrics shows a maximum as a function of average FO moles in the nonionic. Oil/water interfacial tension shows an expected reverse trend. The optimal EO moles (for maximal detergency) show a monotonically increasing trend when plotted as a function of the ratio of nonionic to anionic concentration for a fixed level of electrolyte. The optimal EO moles also increase with increasing level of electrolytes in the system. However, the effect of nonionic/anionic ratio is much stronger than the effect of electrolytes on the optimal EO moles.     

Preparation and surface active properties of alcohol ethoxylates with an amide oxime terminal group

Amide oxime compounds have become of major interest because they can complex with uranium, gallium and various transition metal ions. In this work surface active amide oximes were prepared to make some functions of the amide oxime group exhibit as molecular aggregates in aqueous media. Amide oximes were obtained from nitriles which were prepared by the cyanoethylation of alcohol ethoxylates with a monodispersed oligo(oxyethylene) group. Surface active properties of these compounds were measured under various conditions and were compared with nonionics of the alcohol ethoxylate type. The pKa₁ values of these amide oximes were about five, and they acted as cationic surfactants under acidic conditions and nonionic ones under neutral and basic conditions. When they served as nonionics, the cloud point, CMC, γ_CMC and foaming properties of surface active amide oximes were similar to other alcohol ethoxylate nonionics.     

Removal of fatty soil from glass by surfactants and surfactant-builder compositions

Previous papers have reported radiotagged fatty soil removal from glass either by solvents or by aqueous solutions of sodium tripolyphosphate and other builders. This paper provies soil-removal data for aqueous systems of both pure and built surfactant compositions of the nonionic and alkylbenzene sulfonate types. In general, nonionics are the most effective detergents for the system fatty soil/glass; the 10-mole ethylene oxide adduct products show peak soil-removal. Nonionic surfactants appear most effective for soil removal when used in baths closely approaching their cloud-points. Though modification of hydrophobe by EO addition can affect cloud point, peak soil-removal effectiveness seems to be controlled by hydrophobe selection. Highest soil removal for the alkylbenzene series occurred with the longer alkyl chain (pentadecyl). Admixture of surfactant and sodium tripolyphosphate provided synergistic compositions with certain 10-EO surfactants. Building of anionics markedly improved soil removal over the pure material but seldom exceeded the removal by STP alone. Presented at 34th fall meeting, American Oil Chemists' Society, New York, October 17–19, 1960.     

Optimization of nonionic surfactants for hard-surface cleaning

The hard-surface cleaning performance of various nonionic homologs was evaluated as a function of carbon chain length, ethylene oxide (EO) content, blending and concentration. Results show carbon chain length to be very important to hard-surface cleaning. Performance significantly increases as carbon-chain length decreases, probably as a result of an increase in solvency properties as carbon chain length is decreased. EO content is also important, particularly if nonionics with longer carbon chain lengths are used. Surfactant concentration (dilution) has little effect on the optimum ethylene oxide content but significantly affects the optimum carbon chain length of the hydrophobe. With 5% homolog solutions, the optimally performing nonionic contains a C6 hydrophobe, but with 0.2% solutions, the optimal carbon chain length is shifted to the C8–C10 range. This is thought to result from a trade-off between the surfactant and solvent properties of the nonionic. Overall results show the optimal nonionic for hard-surface cleaning to consist of a blend of C6, C8 and C10 alcohols ethoxylated to a 50% EO level. Commonly used surfactant systems, e.g., alkylphenol ethoxylates and alkylphenol ethoxylate (APE)-butyl cellosolve (BC) blends, were also examined. Results show that alkylphenol ethoxylates give relatively poor performance compared with lower molecular weight linear nonionics because of the large size of their hydrophobe. Under concentrated use, a synergism does exist between APE and BC, but under dilute conditions, the addition of BC is ineffective. BC does not help the performance of low molecular weight nonionics. Surfactant-soil diffusion studies indicate that surfactant penetration of the soil may be the primary mechanism involved in the hard-surface cleaning of solid soils. Presented May 10, 1983, at the 74th Annual Meeting of the AOCS, Chicago, IL.     

城市污水回用的现状与展望

城市污水再生水作为城市供水的一种新的可靠水源正在受到人们的日益关注。对城市污水回用技术、回用途径展开了综述，并对回用的经济效益和环境效益进行了分析，最后介绍了城市污水回用中存在的一些问题以及发展前景。     

Mekorot's research activity in technological improvements for the production of unrestricted irrigation quality effluents

Israel is a country situated in a semi-arid zone with insufficient natural water resources. Due to the excessive abstraction as compared to water availability, some of the seashore aquifers have been depleted and there is a danger of excessive salinity in the aquifers. Wastewater effluent reuse and desalination have become the main alternative sources of water to compensate for the future water shortage. The main reuse activity in Israel is agricultural irrigation (65% of the connected sewage in Israel is reused for this purpose), while most technological efforts are spent for the improvement of unrestricted irrigation quality water. This paper presents the recent years' research activity, in Mekorot National Water Co., in tertiary effluent treatment and effluent desalination in order to achieve high quality water suitable for unrestricted agricultural reuse as well as for public park irrigation, industrial reuse and aquifer salinity reduction.     

On the measurement of critical micelle concentrations of pure and technical-grade nonionic surfactants

The critical micelle concentrations (CMC) of nine commercial nonionic surfactants (Tween 20, 22, 40, 60, and 80; Triton X-100; Brij 35, 58, and 78) and two pure nonionics [C₁₂(EO)₅ and C₁₂(EO)₈] were determined by surface tension and dye micellization methods. Commercially available nonionic surfactants (technical grade) usually contain impurities and have a broad molecular weight distribution owing to the degree of ethoxylation. It was shown that the surface tension method (Wilhelmy plate) is very sensitive to the presence of impurities. Much lower CMC values were obtained with the surface tension method than with the dye micellization method (up to 6.5 times for Tween 22). In the presence of highly surfaceactive impurities, the air/liquid interface is already saturated at concentrations well below the true CMC, leading to a wrong interpretation of the break in the curve of surface tension (γ) vs. concentration of nonionic surfactant (log C). The actual onset of micellization happens at higher concentrations, as measured by the dye micellization method. Furthermore, it was shown that when a commercial surfactant sample (Tween 20) is subjected to foam fractionation, thereby removing species with higher surface activity, the sample yields almost the same CMC values as measured by surface tension and dye micellization methods. It was found that for monodisperse pure nonionic surfactants, both CMC determination methods yield the same results. Therefore, this study indicates that precaution should be taken when determining the CMC of commercial nonionic surfactants by the surface tension method, as it indicates the surface concentration of all surface-active species at the surface only, whereas the dye method indicates the presence of micelles in the bulk solution.     

Deinking of water-based ink printing from plastic film using nonionic surfactants

When plastic film packaging is processed for reuse, residual ink colors the polymer and makes the polymer less stiff, weaker, and denser than the original material. These problems can be avoided if the printing is removed from the plastic film surface. In this study, a commercial polyethylene film with water-based ink printing was deinked (the ink was removed) using nonionic surfactants under a variety of conditions, and the effect of some parameters related to the deinking process were quantified and optimized. Nonylphenol polyethoxylate, ethoxylated alcohol at a pH of 10, and ethoxylated amine at either acidic, neutral, or basic pH level were identified to be effective at deinking. The hydrophiliclipophilic balance (HLB) value and the cloud point are useful parameters for characterizing the effectiveness of nonionic surfactants. For optimal deinking, the HLB of the nonionic surfactants should be as small as possible or the cloud point as low as possible without the deinking temperature substantially exceeding the cloud point. Information related to scaleup of the process was also developed. Soaking plastic film in surfactant solution prior to mechanical agitation significantly decreased the needed agitation time to achieve a given level of deinking. Deinking decreases as the plastic/solution ratio (consistency) increases, and cutting plastic film into smaller pieces improves the deinking at moderate consistency. Increasing agitation speed also enhances the deinking. Experiments performed with pilot-sized paper deinking apparatuses demonstrated that deinking of plastic film using surfactants is technically feasible. Presented at the 88th AOCS Annual Meeting & Expo, May 11–14, 1997, Seattle, Washington.     

The use of surface active agents in tanning of leather

There are about 25 operations in the process of converting hides and skins into leather. Surface active agents are important in a number of these and find wide use in the leather-making industry. Both anionic and nonionic types are widely used while cationics have more specialized use. Sulfated oils (especially cod, sperm and neatsfoot), soaps, sulfated higher alcohols and alkylbenzene sulfonates are the main anionic surfactants used. The nonionics are principally condensation products of ethylene oxide with a secondary alcohol of 11–15 carbons or with octyl and nonyl phenol, introducing 7–10 oxyethylene units. Examples of the cationic type are the quaternary ammonium salts, i.e., lauryl, cetyl and stearyl dimethyl benzyl ammonium chloride. Surface active agents are used at various stages of the leather-making process. They are used in soaking, unhairing, bating, pickling, tanning and coloring, where they serve principally as processing aids. They find more important use in fatliquoring, impregnation and finishing, where they become a part of the leather composition. Certain surfactants, namely, chrome complexes of fatty acids and perfluoro acids, and long chain alkenyl succinic acid have been used to impart water repellent properties to leather. Recent research shows promise of developing new uses for surfactants in the tanning industry. Long chain quarternary ammonium salts have shown promise as a short term preservative for freshly flayed hides and skins. An amphoteric surfactant, i.e., a long chain fatty amino acid of the structure RNHCH₂CH₂CO₂H, has shown promise as leather lubricant with improved resistance to drycleaning solvents. One of eight papers to be published from the Symposium “Surface Active Agents in the Textile Industry.” E. Market. Nutr. Res. Div., ARS, USDA.     

Correlation between critical micelle concentration,fatty soil removal,and solubilization

Using two model soil-detergent systems (hard substrate/triglyceride; cotton/fat, mineral oil, graphite) it was shown that soil removal begins at, or near, critical micelle concentration (eme), confirming the work of other investigators with different systems. Maximum detergency occurs at concentrations considerably in excess of cmc, varying some 6 to 10 times cmc for different surfactants. An equation for soil removal showed excellent fit of experimental values for both detergency systems. Direct correlation between cmc, solubilization (of several materials), and soil removal was demonstrated. Marked differences between surfactant type and solubilization of triglycerides were found. The nonionic surfactants were excellent solubilizers for triolein correlating with their effective soil removal. Neither sodium oleate nor sodium tripolyphosphate effectively solubilized the triglyceride but both are effective soil removers, suggesting that their soil removal mechanism differs from the nonionics, possibly as an emulsification or displacement mechanism. Solubilization of triglyceride occurs most effectively considerably in excess of cmc.