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.     

Soil removal in relation to total work input; a calorimetric approach for model wash systems

A simple, straightforward method, utilizing the concepts of classical adiabatic calorimetry, for direct measurement of total energy delivery to bench scale clothes washing systems is described. The results of such measurements can be expressed in conventional work units such as calories per unit weight or per unit area of fabric. Using this method, total energy input is measured and related to soil removal in model wash systems using a standard cotton soil cloth. The relationship between energy input and soil removal is considered for a number of situations involving variations in stroke rate, load weight and detergent concentration. Finally, these results are used to develop a modified definition of detergency which places the emphasis on the efficiency of mechanical energy utilization in a soil removal process.     

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.     

A natural soil and mechanism of removal

Nitrogen compounds in natural soils are studied in relation to their effect on the soil removal mechanism in detergency. Nitrogen compounds in various forms and in fairly large amts are found in natural soils, and more than 24% of these nitrogen compounds are presumed to be high mol wt nitrogen compounds or proteins. These high mol wt nitrogen compounds which cannot be removed by water can be removed by the detergent action of sodium dodecyl benzene sulfonate (DBS). When the detergency of DBS was compared with nonyl phenol-polyoxyethylene adduct, the detergency for artificial soil cloths did not coincide with results obtained with naturally soiled cloths. These data suggest that some interaction between DBS and nitrogen compounds might have contributed to the detergent action. If proteins were added to the present artificial soil formulation, better correlation might be expected between artificial and natural soil detergency results in DBS evaluation.     

Improved cold-water detergency of malodourous soil correlating with hydrophilic–lipophilic deviation concept

The persistence of sebum after low-water-temperature washing can contribute to malodor and microbial growth during subsequent use; thus, this work focuses on improved sebum removal. The detergency of sebum at various hydrophobic–lipophilic deviation (HLD) values was performed using 0.1 w/v% C_12-13-8PO-SO₄Na and C₈-4PO-1EO-SO₄Na at 1:1 molar ratio. The detergency of synthetic sebum on 87/13 polyester/spandex was relatively poor (70% removal) at HLD = 0. Various additives (heptanol, dipropylene glycol n-butyl ether, decyltrimethyl ammonium bromide or sodium benzoate) were explored and it was found that none of them could facilitate sebum removal on the 87/13 polyester/spandex surface. On the other hand, adding low molecular weight primary amines (ethylene diamine, or monoethanolamine [MEA]) in the surfactant system without salt showed sebum removal of 70%–80% depending on the amine molecule. Adding MEA as a detergency additive with salt appeared to achieve good detergency (>80% removal) at all studied HLD numbers between −1.0 and 1.1 and the maximum detergency (approximately 90% removal) was observed at the optimum formulation (HLD = 0). The formulation pH with added MEA decreased from 11 to roughly 9. Detergency performance with added MEA was not dependent on pH within the studied basic conditions. The principal cold water sebum removal mechanism was found to be detachment of solid sebum fractions, dispersed in the detergent bath or floating on the bath surface.     

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.     

Mechanistic Studies of Particulate Soil Detergency: II: Hydrophilic Soil Removal

In this work, the removal mechanism of kaolinite and ferric oxide (model hydrophilic particulate soils) from hydrophilic (cotton) and hydrophobic (polyester) fabrics was studied using three surfactant types: sodium dodecyl sulfate (SDS), octylphenol ethoxylate (OP(EO)10), and cetyltrimethylammonium bromide (CTAB). This work investigated the relations between zeta potential, surfactant adsorption, contact angle, solid/liquid spreading pressure, and dispersion stability in washing solutions as compared to detergency performance and antiredeposition as a function of surfactant concentration and pH level. The SDS showed the best detergency for both particulate soils, followed by OP(EO)10, with CTAB being the least effective surfactant. For SDS, the electrostatic repulsion between fabric and soil was found to be the dominant force for hydrophilic particulate soil removal. For the nonionic surfactant OP(EO)10, electrostatics are also important and steric effects aid particulate soil detergency. Electrostatic forces and solid/liquid interfacial tension reduction aids CTAB detergency. These same detergency mechanisms have previously been found for the case of hydrophobic soil removal from fabrics. Dispersion stability did not prove to be a dominant mechanism governing particulate soil detergency. From the SEM photos of soiled fabric, ferric oxide attaches to the fabric surface with no entrapment between fabric yarns; moreover, ferric oxide tends to form larger aggregates on cotton compared to polyester fabric. The adhesion of larger particles is hypothesized to be weaker than the smaller ones. Therefore ferric oxide can be more easily removed from cotton fabric than polyester. The SEM photos for kaolinite show little visual difference in particle agglomeration on polyester compared to cotton. Removal of kaolinite from cotton was found to be higher than from polyester, but there is less difference than for ferric oxide.     

水基厨房清洁剂的研制

文章通过表面活性剂复配技术研制出一种水基厨房清洁剂,并获得了该清洁剂配方中各组分含量与洗净力之间的变化规律。结果显示,所制备的厨房清洁剂去污快速,洗净力可达99.0%以上;且产品中不添加有机溶剂,碱度低,对不锈钢、铜、铝等常见金属无腐蚀,对厨具烤漆表面无损伤,具有广阔的市场前景。     

Mechanistic Studies of Particulate Soil Detergency: I. Hydrophobic Soil Removal

The mechanism of particulate soil detergency using aqueous surfactant systems is not well understood. In this research, carbon black (model hydrophobic soil) removal from a hydrophilic (cotton) and hydrophobic (polyester) fabric is studied using anionic, nonionic, and cationic surfactants. The zeta potential, solid/liquid spreading pressure, contact angle and surfactant adsorption of both soil and fabric are correlated to detergency over a range of surfactant concentrations and pH levels. Electrostatic repulsion between fabric and soil is generally found to be the dominant mechanism responsible for soil removal for all surfactants and fabrics. Steric effects due to surfactant adsorption are also important for nonionic surfactants for soil detachment and antiredeposition. Solid/liquid interfacial tension reduction due to surfactant adsorption also aids in detergency in cationic surfactant systems. Wettability is not seen as being an important factor and SEM photos show that entrapment of soil in the fabric weave is not significant; the particles are only attached to the fabric surface. Anionic surfactants perform best, then nonionic surfactants. Cationic surfactants exhibit poor detergency which is attributed to low surfactant rinseability.     

The effect of sodium carboxymethyl cellulose on synthetic detergent systems

Summary Certain forms of sodium carboxymethyl cellulose have been shown to be highly effective as synthetic detergent promoters. Formulations containing a sodium alkyl aryl sulfonate type of synthetic detergent, alkaline salts and a type of sodium carboxymethyl cellulose developed for high detergency promoting properties surpass high quality fatty acid soaps in both carbon soil removal and whiteness retention on cottons. Methods having a relatively high order of precision for the evaluation of detergency have been presented in detail. By these methods two fundamental characteristics of detergency—as applied to the laundering of cotton fabrics may be independently measured.     

Cold Water Detergency of Triacylglycerol Semisolid Soils: The Effect of Salinity,Alcohol Type,and Surfactant Systems

Cold water detergency of triacylglycerol semisolid soils is much more challenging than liquid vegetable oils due to poorer interaction between surfactants and semisolid soil. This research seeks to improve the removal efficiency of semisolid soils below their melting points using surfactant-based formulations containing different alcohol additives. To this end, cold water detergency of solid coconut oil and solid palm kernel oil was investigated in various surfactant/alcohol systems, including single anionic extended surfactants, single nonionic alcohol ethoxylate surfactants, and a mixture of anionic surfactants. A series of alcohols (2-butanol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, and 1-decanol) were added to the surfactant formulations to investigate cold water detergency improvement. While cold water detergency using surfactants alone was poor, it was considerably improved when optimum salinity (S*) and 1-heptanol, 1-octanol, or 1-nonanol were introduced to the studied surfactant formulations. The maximum detergency of solid coconut oil exceeded 90% removal in the 0.1 w/v% C_14-15-8PO-SO₄Na/0.2 w/v% 1-octanol/4 w/v% NaCl system (a final optimized surfactant system) at a washing temperature of 10°C versus 22.9 ± 2.2% in the surfactant alone (not at optimum salinity and no additive). Further analysis showed that improved cold water detergency using surfactant/intermediate-chain alcohols/NaCl could be correlated with high wettability (low contact angle) as well as favorable surfactant system-soil interaction as observed by lower interfacial tension values. In contrast, the improved cold water detergency was observed to be independent of dispersion stability. This work thus demonstrates that surfactant system design, including additives, can improve cold water detergency of semisolid soils and should be further explored in future research.     

Effect of Surfactant Systems,Alcohol Types,and Salinity on Cold-Water Detergency of Triacylglycerol Semisolid Soil. Part II

Our prior work found that detergency of coconut oil was relatively poor using C_14-15-8PO-SO₄Na alone but showed promising improvement with the presence of linear intermediate-chain alcohols (C7–C9 alcohols) in the surfactant formulation. The maximum detergency exceeded 90% removal using 0.1 w/v% C_14-15-8PO-SO₄Na/0.2 w/v% 1-octanol/4 w/v% NaCl (final optimized surfactant system) at 10 °C. The current work thus seeks to further investigate surfactant formulations capable of providing improved detergency performance. Different 50% linear anionic extended surfactant structures (LC_14-15-8PO-SO₄Na, LC_14-15-8PO-3EO-SO₄Na, and LC_14-15-8PO-7EO-SO₄Na) were compared with the branched C_14-15-8PO-SO₄Na previously studied. Detergency of coconut oil using C_14-15-8PO-SO₄Na at 8 w/v% NaCl (S*) still performed more effectively than these new surfactant systems. The addition of octanol as a detergency additive was further studied, and it showed that S* reduced from 8 w/v% NaCl to 4 w/v% NaCl for 1-octanol and to 2 w/v% NaCl for 2-octanol and 2-ethyl-hexanol in the C_14-15-8PO-SO₄Na surfactant formulation. Coconut oil removal significantly improved detergency from roughly 49% for no alcohol with 8 w/v% NaCl, to 83% for 2-ethyl-hexanol with 2 w/v% NaCl, to 95% for 1-octanol with 4 w/v% NaCl, and to 98% for 2-octanol with 2 w/v% NaCl. Further studies on octanol concentration showed that decreasing 1-octanol from 1.2% (90 mM) to 0.2% (15.3 mM) and 2-octanol from 1.2% (90 mM) to 0.5% (38.5 mM) still maintained detergency over 90% removal. In this work, cold-water detergency was found to correlate with low interfacial tension above the melting point, improved wetting of the semisolid soil, and oil solubilization in surfactant micelles.     

Laundry Detergency of Solid Non-particulate Soil or Waxy Solids: Part I. Relation to Oily Soil Removal Above the Melting Point

In this work, methyl palmitate or palmitic acid methyl ester, a monoglyceride, was used as both a model solid fat below the melting point and as an oily soil above the melting point. An anionic extended surfactant [branched alcohol propoxylate sulfate sodium salt (C₁₂₃‐(PO)₄‐SO₄Na)] was used to remove methyl palmitate from cotton and from polyester. Above the melting point (~30 °C) of methyl palmitate, the maximum oily soil removal was found to correspond to the lowest dynamic interfacial tension, as is common with liquid soils. Below the melting point, the lower the contact angle of the wash solution against the soil (indicating higher wettability), the higher the solid fat soil detergency. The removed methyl palmitate was found to be mostly in unsolubilized droplets or particles with a small fraction of micellar solubilization for both solid and liquid forms. The presence of surfactant can prevent the agglomeration of detached methyl palmitate particles in both liquid and solid forms, reducing redeposition and enhancing detergency. Below the melting point, the surfactant aids the solution wetting the surfaces, then penetrating the waxy solid, causing detachment as small particles, and dispersion of these particles. Unlike particulate soil detergency, electrostatic forces are not the dominant factor in fatty soil detergency.     

酶与表面活性剂的协同去污机理研究

研究了两种碱性蛋白酶（Ｓａｖｉｎａｓｅ,Ｅｓｐｅｒｓｅ）与三种表面活性剂（ＬＡＳ、ＡＥＳ、ＴＸ １０）对普通炭黑污垢、酪蛋白污垢及复合污垢的去污性能,发现酶与ＴＸ １０、ＡＥＳ配伍有增效去污作用,而与ＬＡＳ配伍有消减去污作用。酶与ＬＡＳ配伍使用时,洗涤１０ｍｉｎ后酶的相对活性降至８％;而加入稳定剂的对比实验,洗涤４０ｍｉｎ后仍能保持５２％～６２％的相对活性,相应对酪蛋白污垢的去除率从原来的８１％提高到９５％,表明加入稳定剂可以使酶与ＬＡＳ的配伍变为增效去污作用。提出了两者之间的协同增效去污机理模型。     

The correlation of washability with the rate of surfactant adsorption

A relation between the rate of adsorption of surfactant molecules at a gas-liquid interface and the soil removal ability of the surfactant solution is presented. The relation is of the form SR=A+Bk+Ck² where SR is the percentage soil removed, A, B, and C are constants, and k is the first order rate constant for the adsorption process. The relation is empirical and as yet has not been coupled with a fundamental explanation of the detergency process on a molecular scale. The maximum soil removal does not always occur at the highest rate constant but may reach a maximum at an intermediate value. The soil removal process seems to be different above the CMC than below it. For the different surfactants studied, the soil removal is higher for the surfactant with larger rate constants. The rate of surfactant adsorption was obtained from dynamic surface tension measurements made with the oscillating jet technique. Soil removal information was obtained from laboratory tests using a Terg-O-Tometer and reflectance measurements on standard cloth swatches. Cationic, nonionic, and anionic surfactants were studied. Specifically, the surfactants were Triton X-100 (an octyl phenol with 8 or 9 ethylene oxide units), NaDBS (sodium dodecylbenzene sulfonate), and CTAB (cetyl trimethylammonium bromide). The surface tension time range of 5 to 60 milliseconds and soil removal ability of these surfactants was investigated over the temperature range of 20 to 60C, and the concentration range of 0.0003 to 0.009 M.     

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%.     

Detergency and mechanism of soil removal in detergent-enzyme system

Enzyme effects on detergency were studied at a relatively low temperature (20 C) using naturally solied fabrics (collars on working clothing) and 2 types of artificially soiled cotton cloths, milk-soiled and carbon-milk-soiled. Results of the test showed that protease has a favorable effect on detergency even at 20 C and improves the removal of common soils solid or oily, as well as protein-based soils. The protease also was proved fully effective under mechanical agitation in the presence of detergents. Futhermore, the role of enzyme was discussed based upon gel filtration of the washing bath which treated the milk-soiled cloths. The degradation of protein by protease to a molecular weight of ca. 10,000 to 50,000 was proved to be fairly important for removal of soil protein. It also was found that endo-peptidase action is more effective than exo-peptidase action. Based upon these findings, a problem in activity evaluation method for enzymes as detergent compoments also was presented.     

Statistical analysis of washing efficiency for solid particle soil

In a previous study, statistical method using two distributions was applied to analyze detergency of oily soil. The method uses statistical distributions of detergent power and adhesive force of soil. In this paper, this method was applied to an analysis of detergency of solid particles. Soiled cotton cloth was prepared with red iron oxide dispersion liquid in Terg-O-Tometer. Four-time consecutive washings tests were conducted with dodecyl sulfuric acid sodium salt (SDS) and alcohol ethoxylate (AE) aqueous solutions in Terg-O-Tometer. Change of removal efficiencies due to repetitive washing was utilized to seek the two distributions. Predicted removal efficiencies calculated from computer simulation corresponded to experimental values. Different adhered states of soil, prepared by varying soiling conditions, were expressed as Removal Resistance. As soiling mechanical power increased, Removal Resistance shifted toward higher adhesive force of soil and an amount of soil had also increased. Iron oxide concentration only had an affect on an amount of soil. The results showed that the method using two statistical distributions can be applied to the detergency of solid particle.     

Methyl Ester Sulfonate: A High-Performance Surfactant Capable of Reducing Builders Dosage in Detergents

The detergency performance of α-sulfo fatty-methyl ester sulfonate (α-MES) under different water hardness conditions was compared against the dominant workhorse in Home Care products, linear alkylbenzene sulfonate (LAS). Results demonstrate that α-MES has a higher soil removal index and its detergency performance is not drastically affected by water hardness, compared to that of LAS. The addition of α-MES to LAS also shows an improved cleaning performance and better water hardness resistance, due to the structural characteristics of α-MES, which allow the molecules to be relatively insensitive toward polyvalent ions such as Ca²⁺ and Mg²⁺. The washing performance of α-MES, α-MES/LAS, and LAS with different builders at various dosages was studied, and the results indicated that the dosage of builders in the detergent product could be reduced up to 33% with the application of α-MES, while the detergency is not sacrificed.     

Measuring detergency of oily soils in the vicinity of phase inversion temperatures of commercial nonionic surfactants using an oil-soluble dye

We have used a simple technique to measure the detergency of model oily soil from 63∶35 blended polyester/cotton fabrics using solutions of commercial linear lauryl alcohol ethoxylates in the vicinity of their phase inversion temperatures (PIT). The method involves incorporation of an oil-soluble dye in the oily soil, and measurement of reflectance at an appropriate wavelength directly on the fabric before and after wash. This technique was validated for our systems, and it provides an additional visual cue for the efficiency of soil removal. Hexadecane, which represents the linear hydrocarbon part of sebum (typical soil encountered in detergency) and has been widely studied in the literature, was used as the model oily soil. Maximal detergency occurs as a function of washing temperature at approximately 35, 62, and 80°C for ethoxylates with four, five, and six moles of ethylene oxide (C₁₂EO₄, C₁₂EO₅, and C₁₂EO₆), respectively. The oil/water interfacial tension, measured using the spinning drop method, exhibits corresponding minima and complements the detergency results. Addition of sodium carbonate, a salting-out electrolyte, decreases the optimal detergency temperature (ODT) of C₁₂EO₅, shifting its behavior toward C₁₂FO₄ whereas addition of anionic surfactant increases the ODT of C₁₂FO₅, mimicking the behavior of a higher ethoxylate.