Hard surface detergency

In a study of hard surface detergency using glyceryl trioleate, oleic acid, and octanoic acid soils with three types of anionic and three types of nonionic syndets, only potassium laurate showed maximum detergency at the CMC (critical micelle concentration), with the potassium laurateoctanoic acid system being an exception. In general glyceryl trioleate and oleic soil removal (180°F.) at the CMC was low, not over 40%; octanoic acid detergency at the CMC was substantially higher, 65 to 83%. Considerable differences in removal of the various soils by the same surfactants were found. A generalization was observed in the detergency of glyceryl trioleate soil—soil removal increased sharply on passing the CMC with increasing concentration until approximately 90% detergency was reached, at which point soil removal began to level off and approach 100% with a much smaller slope. Visual observations of the cleaning processes suggested a partial answer for the differences in soil removal. Removal or glyceryl trioleate soil by both anionic and nonionic syndets appeared to be due chiefly to a displacement action caused by preferential wetting of the basis metal. Removal of octanoic acid by the nonionic surfactants in a diffusing cloud of small particles seemed to be due to solubilization followed by emulsification and precipitation of the acid soil. Several relationships were discovered in two series of analogs (polyethenoxyethers of nonyl phenol and tridecyl alcohol). It was found that the ratio of the HLB (hydrophile-lipophile balance) values of two analogs was approximately equal to the fifth root of the ratio of their CMC values. The correlation held for analogs varying by as much as 15 moles ethylene oxide. A linear relationship was also found between HLB value and the reciprocal of the ethylene oxide mole ratio for the polyethenoxyethers of nonyl phenol.     

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.     

Correlation of detergency with physicochemical factors

Summary It is felt that it would be of interest to conclude this paper by showing some of the correlations already established for selected soil-surfactant series of systems, with particular reference to the variation of the linearity constants K₁ and K₂ of these systems with corresponding soil or surfactant physicochemical factors. Table IX gives the detergency functions for these multi-soil, common surfactant, and multi-surfactant, common soil, series of systems.     

Behavior of surfactant mixtures in model oily-soil detergency studies

A study of roll-up in a model oily-soil detergent system has shown that the addition of a second surfactant in a minor amount to an effective detergent can either enhance or inhibit roll-up. Which effect takes place depends on the relative surface activity of the components, the levels used, and, for ionic surfactants, the electrolyte content. Addition of anionic surfactants can reduce the performance of an effective nonionic under low ionic strength/low hardness conditions. However, in high ionic strength/high hardness solutions, where the anionic is effective, the situation is reversed and addition of the nonionic component can, in some cases, reduce the rate of roll-up. Roll-up behavior appears to be controlled by the oil/ water interfacial tension. When the interfacial tension increases above a critical value, roll-up is inhibited. A theory that has been used to predict surface tensions of mixtures is also useful in estimating oil/water interfacial tensions. The theory provides an understanding of why the interfacial tension can rise when mixed micelles are formed.     

A greasy soil hard surface cleaning test

A laboratory screening test for greasy soil removal from hard surfaces using lard, vegetable shortening and vegetable oil darkened with finely divided charcoal on white, latex-painted masonite wallboard is described. Cleaning by a wet sponge in the Gardner apparatus is measured by reflectometer. Statistical evaluation of results based on comparisons of 8 competitive cleaners is documented. Curves showing performance vs concentration of cleaners are given.     

Application of statistical analysis to mixed soil detergency

In previous studies, statistical method using distribution of detergent power and that of resistance of soil against washing was applied to analyze detergency of oily soil and solid particle soil. In this paper, this method was applied to an analysis of detergency of mixed soil. Artificially soiled cloth prepared by aqueous dispersion method was used as a mixed soil sample. Four-time consecutive washing tests were conducted under the same washing condition in Terg-O-Tometer using two kinds of detergent solution and distilled water. Change of removal efficiencies due to repetitive washing was used to determine the two distributions. Result shows that detergent power can be expressed as cumulative distribution function. In washing simulation using the cumulative distribution functions, the predicted removal efficiencies corresponded with experimental values. Moreover, the effect of soil aging on distribution of soil resistance against washing was found to move the distribution curve toward high resistance. These results show that the method using two statistical distributions can be applied to the detergency of mixed soil.     

A motor oil soil for detergency testing

Bright Stock/Pale Oil (BS/PO) soil represents a typical motor oil soil, but it is more constant in composition than clean or dirty commercial motor oil. It does not require the addition of any dye, as is the case with mineral oil or cooking oil, and when applied to cloth, it produces very uniform soilings. The statistical reproducibility of detergency tests run with BS/PO is better than mineral oil and about as good as sebum.     

Improvements in detergency precision with radioactive soil

Recent work on the use of seven-component, doubly labeled radioactive soil to evaluate deter-gency has depended on the analyses of the fabric for residual soil. Because of the variation of soil concentration within and between fabric swatches, considerable replication was required to lower the standard deviations to ±10%. A method for the analysis of wash water has been developed which requires much less replica-tion and achieves higher precision (<±2%). The method is based on the use of an inhomo-geneous scintillator, which can emulsify, or at least suspend, large volumes of water in a liquid scintillator while maintaining good counting efficiency. Studies of closure, i.e., amount of soil recovered in wash water plus fabric compared with soil introduced into the Tergotometer, have demonstrated that the method is reasonably accurate and quite precise.     

Statistical analysis of detergency tests with a natural soil

Factorial experiments are described for detergency tests using a natural soil. The tests are carried out over several soil-wash cycles using soil rubbed onto test swatches from the surface of the skin. The significance of the results is increased by removing the variability of soiling among different individuals from the wash treatment totals and by using a log transformation on the original data. Factors investigated include wash water temperature, water hardness, concentration of surface active agent and concentration of builders.     

A triply labeled particulate soil for detergency studies

A kaolinite type of clay made radioactive by neutron irradiation (Spinks Bandy Black), described in an earlier report, has undergone extensive testing to determine its suitability as a particulate component of an artificial radioactive soil. The other components of the soil are labeled with¹⁴C and tritium. The incorporation of the radioactive clay into an established soil required the development of a reproducible padding procedure and the development of suitable analytical methods for the clay, as well as modification of the existing method for¹⁴C and tritium in the presence of the radioactive clay. A problem arose when it was noticed that, after the padding step, the specific activity of the clay adhering to the fabric was higher than the starting clay. This was traced to the fact that Spinks Bandy Black is not only a mixture of varying particle sizes, but of changing chemical composition with varying particle size. Thus, one could not readily convert radioactivity to weight. The problem has been resolved by resorting to chemical analysis for SiO₂ and Al₂O₃ of a few representative swatches from each padding run to give the weight of clay per swatch and thus the specific activity. Chemical and radiochemical analyses of the swatches after laundering have demonstrated that further disproportionation of the clay is minor. A large Terg-O-tometer washing study was made under a variety of conditions to determine the precision of the method for all three labeled components of the soil. It was found from sets of four replicates that the precision for clay detergency is ±2.5%; for the polar fatty soil detergency (¹⁴C) is ±2.3%; and for the nonpolar fatty soil detergency (tritium) is ±3.5%. Redeposition of the clay in the presence of a built detergent is usually less than 1%.     

The development of a particulate radioactive soil for detergency studies

A sample of kaolinite clay has been tagged by neutron irradiation. After an extended cooling period (18 months) to allow the short lived nuclides to decay, the clay is still sufficiently radioactive to use it in detergency studies. Extraction tests show that about 25% of the radioactivity is labile, i.e., removed by sodium tripolyphosphate but that the remainder is strongly fixed in the clay matrix, resisting extraction by built detergents. The clay has a number of nuclides emitting both beta and gamma radiation. Analytical methods for both types of radiation have been developed for use with fabrics and wash waters. The clay has been combined with the doubly labeled fatty soil (³H and¹⁴C) to make a triply labeled particulate soil. Tergotometer runs with three test fabrics show good precision for all three labeled components of the soil. Redeposition measurements were also made and showed that a considerable fraction of the residual clay on a washed swatch may in fact be due to redeposition rather than retention. Some problems remain in the application of this synthetic soil: the padding step must be modified so that the clay is more tenaciously bound to the fabric; a more automatic method of padding is required to handle large numbers of samples; the specific activity of the clay should be increased so that liquid scintillation analysis for all three tagged components can be made on a single sample of wash water. Presented at the AACC-AOCS Joint Meeting, 1968, Washington, D.C.     

The determination of doubly labeled artificial soil in detergency studies

A liquid scintillation method for the determination of carbon-14 and tritium labeled soil on white fabric has been developed. The method involves the use of an external standard to determine the counting efficiency for each isotope. The requirement that these determinations be made on swatches of fabric complicates the analysis because of their variable antiquenching effect. The method has been appied to cotton, Dacron, nylon, and Dacron/cotton. A computer program has been written which accepts the raw counting data and performs all necessary calculations, printing out the data in a convenient form. The great convenience of the method has encouraged its application to large scale screening studies without sacrificing the precision, accuracy, or selectivity normally associated with small model systems.     

Use of experimental design in detergency tests with a natural soil

A balanced incomplete block design is used to obtain detergency data in a test where cloth swatches are soiled by rubbing against the skin. The design provides increased precision in the data by adjusting for differences among soilers. The wash treatments are part of a second order rotatable design in three variables: the ratio of sodium nitrilotriacetate to sodium tripolyphosphate builder, pH of the wash solution, and temperature. The effect of builder ratio was not highly significant. Soil removal increased with higher pH and went through a maximum with increase in wash temperature. Redeposition was also measured by reflectance values obtained for unsoiled areas of the swatches. Redeposition increased with increase in wash temperature. One of five papers presented at the Symposium, “Basic Aspects of Detergency,” AOCS-ISF World Congress, Chicago, September 1970.     

Evaluation test for scouring agents: Fatty soil on a hard surface

A method has been developed to rate the scouring ability of abrasive cleaners on a tough fatty film which is baked onto an aluminum panel. Results were obtained on a comparative basis, and are best determined by one person using as few panels as possible for each investigation. The soiled surface was prepared by spreading 5 ml of a lard-chicken fat mixture on one side of the panel, and baking for 5 min at 575F. Three classes of scouring agents were studied, steel wool with soap, silex which was resin-bonded to nylon fiber and silex on a dish cloth. Results can be expressed as Scouring Efficiency, and related to an arbitrary standard designated as 100%. Presented at the AOCS Meeting in New Orleans, 1964.     

Fatty Acid soil detergency performance of poly(sodium α-hydroxyacrylate)

Effects and properties of poly(sodium α-hydroxyacrylate) (PHA) on removal of stearic and oleic acids from cellulosic filter paper under various wash conditions were evaluated and compared with those of sodium dodecyl sulfate (SDS) by using differential scanning calorimetry. PHA had a much greater effect on the removal of stearic and oleic acids than SDS under the same washing conditions. PHA produces complexes with fatty acids on filter paper during the washing process, and in DSC these complexes have endothermic peaks at temperatures higher than the melting point of the fatty acids. The complexes are formed at temperatures both below and above the melting point of the fatty acid and are removed completely from filter paper by rinsing. The conditions of temperature, time, and PHA concentration during washing all affected the formation of the complex and the removal of fatty acid. Whether the fatty acid chain was saturated or not did not affect the formation of a complex.     

金刚烷基Bola型表面活性剂的设计、合成及表面活性

以1,3-二溴金刚烷为起始原料,首先在Lewis酸催化作用下与苯酚发生傅-克烷基化反应生成1,3-二(4-羟苯基)金刚烷(DPAD);DPAD再经Williamson缩合反应和中和反应合成了新型金刚烷基Bola型表面活性剂1,3-二(4-(2-乙氧基磺酸钠)-苯基)金刚烷。采用IR、¹H NMR和元素分析等手段确定了各中间物及产物的结构,测试了1,3-二(4-(2-乙氧基磺酸钠)-苯基)金刚烷的表面活性。考察了关键反应步骤(Williamson缩合反应)溶剂、卤代磺烷基化试剂、反应温度、反应时间和物料比对产物收率的影响。在优化的反应条件下,1,3-二(4-(2-乙氧基磺酸钠)-苯基)金刚烷的总收率可达72%。     

Kinetic studies of detergency. II. Effect of age,temperature, and cleaning time on rates of soil removal

The effects of variation in temperature, flow rate, cleaning time, and age were studied in a model circulation system. The results are recorded as changes in the rate constants k₁ and k₂ and changes in the relative proportions of the two soil species. The removal of tristearin in this simple system was found to proceed by two independent mechanisms, acting simultaneously. The first, named the “flow mechanism,” is dependent on time, and its rate increases with flow rate. The second, which the authors term the “Dupré mechanism,” is not dependent upon time and arises from the air-detergent interface that moves over the surface. The Dupré effect is independent of flow rate at all rates of flow. In most of the experiments the Duprè mechanism accounted for about 90% of the removal of tristearin. A comparison is made between the removal of monomolecular films and thin polymolecular films. It is shown that the empirical finding of apparently simple first-order kinetics is not inconsistent with the complex processes that remove tristearin from the surface.     

Studies of soiling and detergency

A study was made of the desorption of carbon-14 labeled fatty acid, fatty alcohol, hydrocarbon, triglyceride, and hydrophobic and hydrophilic particulate carbon from cellulose, Nylon, and polyethylene terephthalate films into aqueous solutions of cationic, anionic, and nonionic deter-gents. Use of the polymers in film form as end-windows of a Geiger counter and labeling of the soils with radioactive carbon-14 allowed con-tinuous monitoring of the amount of sorbed material and normalized the usual complication of fiber and fabric geometry so that results ob-tained with different polymers could be directly compared. An excellent correlation was established be-tween fatty soil removal from polyethylene terephthalate film and fabric surfaces; thus re-sults obtained with film substrates have practical significance. Wash variables were carefully con-trolled and were altered one at a time to learn their effect on the soil-removal process. Results are discussed in terms of the possible mechanisms of soil removal.     

Study of detergency. I. Effect of the concentration and the kind of detergent in hard water

The effect of concentration and kind of detergent, and nature of oil-on-oil removal efficiency in hard water was studied. Maximum oil removal efficiencies are shown at the same water hardness for a given oil. As the concentration of detergents increases, the water hardness at maximum oil removal efficiency increases and the sharpness of the oil removal peak is lessened. A linear relationship between concentration of detergent and water hardness at maximum oil removal efficiency was found. This relationship is dependent on the nature of the oily soil and kind of detergent.