Soil removal as a rate process

The rate of soil removal during multiple cycle washing has been studied for three artificially soiled cotton test cloths. Results are considered in relation to a soil removal rate concept proposed some years ago by Vaughn, Vittone, and Smith. It is shown that the rate of removal for these soils, when washed in the Terg-O-Tometer with a built, anionic, synthetic detergent, does not correspond to a simple first order rate process as proposed by Vaughn et al. Rather, it was found that under a variety of washing situations the percentage soil removal increased linearly with the log of cumulative wash time. Further, it was shown that for those experiments involving detergent concentration or level of mechanical action, the slopes of these log time relationships, which reflect the rate of soil removal, vary in the expected manner.     

Improvement of cotton cloth soil removal by inclusion of alkaline cellulase from Bacillus sp. KSM-635 in detergents

Alkaline cellulase from Bacillus sp. KSM-635 (EC 3.2.1.4) had reproducible detergent effects on cotton cloth that was artificially or naturally soiled with oily and/or particulate matter, under European washing conditions. The detergent effects of the cellulase, in combination with surfactants, apparently were the result of enzymatic action on amorphous regions of cotton fibers in which soil was trapped. The contribution of cellulase to soil removal increased as (i) the amount of soil in the amorphous regions of fibers in test fabrics was increased and (ii) the inhibition, by soil that adhered to the fibers' surfaces, of the action of the cellulase on fibers was reduced. Alkaline cellulase had the potential to replace, in part, both surfactants and zeolite in detergents, and it reduced washing time and allowed washing at lower temperatures under European washing conditions. The marked detergent effect of cellulase on naturally soiled cotton fabric was visually apparent, and it inhibited the accumulation of ash, calcium, and other inorganic components on cotton fibers during wash-and-wear cycles. These contributions of cellulase to the cleanliness of cotton fabrics were clearly increased by repeated wash-and-wear cycles. Cotton fabrics were not degraded by washing with the cellulase because effective hydrolysis by the cellulase occurred only in the amorphous regions of cotton fibers.     

Detergency study of the synergism between oily and particulate soil on polyester/cotton fabric

The removal of multiphase, multicomponent soils from fibrous substrates depends upon the nature of the soil mixture, the order of application, wash temperature, and type of detergent formulation. By studying these factors, we investigated the synergism between residual oil (triolein) and particulate soil (clay) on a durable press polyester/cotton fabric after laundering with four different detergents at wash temperatures of 27 and 49 C. To probe the interaction between clay and oil, fabric specimens were soiled with clay only, triolein only, clay followed by an application of triolein, and triolein followed by an application of clay. Four detergent formulations were used to launder the soiled fabrics, including one unbuilt liquid and three powdered detergents with different builder systems. The amount of residual oil (triolein) was determined by radiotracer technique, and the quantities of clay were determined by measuring aluminum by neutron activation. Reflectance measurements were used to calculate fabric whiteness. The soil distributions on and within the textile structure were obtained by scanning electron microscopy using backscattered electron images, secondary electron images and X-ray mapping. Osmium tetroxide was used to tag the oil, while silicon was the elemental tag for clay in the microscopic analysis. Results of the four factors studied can be summarized as follows. (i) In agreement with observations by previous researchers, a mixture of clay and oil is more difficult to remove than either the oil or the clay applied singly. It appears that oil acts as a matrix to bind clay, forming a composite soil. (ii) The specimens that were soiled first with oil and then clay had more soil removed by laundering than the specimens soiled with clay and then oil. Detergency was limited by the encapsulation of clay by the oil and adsorbtion of oil by the clay. (iii) The built powdered detergents were temperature sensitive, while the unbuilt liquid detergent was not. (iv) The built powdered detergents removed more soil (oily and clay) than the unbuilt liquid detergent.     

Test method utilizing dry natural dirt for evaluating laundry detergents

A laboratory test has been developed for screening detergent compositions with respect to the removal of natural dry particulate soil (dirt). The fabrics are soiled uniformly with dirt obtained from a suitable area and then laundered under controlled conditions in a Tergotometer. The total soil removal is determined instrumentally. The test enables the researcher to check the effects of many variables, such as temperature, water hardness, builders, fabric, etc., with a minimum amount of preparation and time. The soil removal data is analyzed by a suitable statistical method, and the results are good indicators of practical performance.     

Evaluation of detergents for washing fabrics

Various methods are used today to check the washing effect of detergents. They differ mainly in whether the cleaning assessment is determined by the use of artificially soiled test fabrics, anonymous naturally soiled laundry in a single wash test, or new family bundles in multiple use and wash test series. Correlation of the information based on the actual field behavior of the different methods is discussed. Applicability of the different systems will depend on the special conditions which call for abbreviated procedures. Multiple use and wash tests are very close to practical use, give information about cumulative effects and thereby allow the detection of small differences. Their disadvantages are high costs and length of time for the test. For a realistic evaluation from a consumer viewpoint, they are of little significance without a ranking scale correlating to consumers’ appraisal. Classification of tested products depends on the kinds of textiles in the family bundles which are used in the detergency evaluation. This factor is important in the detection of correlations between the two methods. For product evaluation and especially for overall quality ratings, the use of test fabrics is satisfactory if a carefully selected combination of these is chosen. Taking into consideration empirical data obtained with standard formulations, one can obtain satisfactory results corresponding to consumers’ appraisals. Stain removal and soil redeposition have to be given the same weight as soil removal. An overall investigation of possible correlations is lacking so that some uncertainties still remain.     

Enzymes in detergents

Factors affecting the performance of proteolytic and amylolytic enzymes in an anionic and nonionic detergent formulation have been studied using stain removal from EMPA blood-milk-ink and cocoa-milk-sugar soil test cloths as a measure of enzyme activity in the detergent solution. Factors considered include enzyme concentration, and temperature and pH of the wash solution. Results on stability of these enzymes in the two detergent formulations under accelerated storage conditions are also given. Presented at the AOCS Meeting, New York, October, 1968.     

Optimisation of Detergent Ingredients for Stain Removal Using Statistical Modelling

Artificially soiled test fabrics are widely used to study the cleaning performance of detergents formulations. In this study, artificial soiled cotton test fabrics were prepared in the laboratory using carbon black as a model soil. Design of experiments was used to optimise the concentration of detergent ingredients for stain removal. A multi‐factorial analysis of variance was used to model the effect of sodium dodecylbenzene sulfonate, nonylphenol ethoxylate, sodium silicate, sodium citrate and sodium carbonate as builders on soil removal. A colourimetric evaluation using the CIELAB system was used to measure soil removal. In general, performance increases with increasing concentration of surfactant, silicate and soda ash.     

A natural soil and mechanism of removal: Part II

Based on the findings of interaction between dodecyl benzene sulfonate (DBS) and high molecular weight nitrogen compounds in natural soil in the first report of this series, artificially soiled clothes containing protein were prepared and a washing test was carried out with a use of DBS or nonyl phenol-polyoxyethylene adduct (NPEO). Cattle serum globulin, cod sperm protamine and feather keratin of wild duck were used as protein. The built DBS detergent showed better detergency on the artificially soiled clothes than the built NPEO detergent at a same surfactant concentration of 0.05%, although no difference was observed in the redeposition test between these detergents. A significant dissolving action of DBS was observed. Results indicate that when discussing the mechanism of dissolution of natural soil or in the course of modifying the artificially soiled clothes, a chemical reaction between DBS and protein had to be considered in addition to the well known physico-chemical surface activity of the surfactant for removal of soil.     

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 detergency test based on rapid aging of unremoved sebum

A laboratory test has been developed for screening detergent compositions with respect to the removal of sebum soil in the absence of particulate soil. The fabrics are uniformly soiled with an aqueous emulsion of synthetic sebum and are then laundered under controlled conditions in a Tergo-Tometer. The unremoved soil is rapidly aged, and the resulting yellowness is measured instrumentally. This test can be run in a minimum amount of time and with a minimum amount of equipment. It enables one to check many variables (such as sequentering capacity, temperature effects, brightener build-up under soiled conditions, etc.) on various fabrics, with or without special treatments. The results are in terms of yellowness, which is recognized by the housewife, and are not a measurement of total soil removal. These values, when combined with grayness values derived from the sebum airborne test, are good prognosticators of practical performance.     

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.     

Palm Oil Removal from Fabric Using Microemulsion-Based Formulations

Laundry detergency of palm oil on a polyester/cotton blend was measured using an anionic extended surfactant/nonionic secondary alcohol surfactant blend under conditions corresponding to ultralow oil/water interfacial tension microemulsion formation. The oil removal for the surfactant blend could exceed 90%, which was greater than that for either component surfactant alone or for a commercial liquid laundry detergent. Presoaking produced better detergency than increasing the number of wash cycles beyond two due to fabric abrasion (leading to a brightness decrease) with an excessive number of wash cycles. Higher oil contact angles and shorter oil droplet detachment times were found to correspond to higher detergency. High speed photography showed that snap-off occurred rather than roll-up for these systems.     

An intelligent washing machine for the evaluation of laundry detergents

A computer-controlled washer can be programmed to evaluate automatically a large number of washing compositions for soil removal. Variable amounts of as many as six different detergent components are added with metering pumps. A continuous roll of soiled cloth passes through a washer and past a reflectance meter onto a take-up reel. Washing action is provided by a vertical reciprocating shaft attached to a plate which rubs on the fabric while tension is maintained by a spring-loaded roller. The length of the wash, number of rinses and addition of components is controlled by the computer program. Upon completion of the wash and rinse cycle, the fabric is advanced about 10 cm. Washed areas appear as lighter colored bands on the fabric. In one mode of operation a large factorial experiment is programmed in advance. After an initial calibration of metering pumps the apparatus runs unattended. In another mode, the computer receives feedback from the reflectance meter and a simplex procedure is used to determine the direction of maximum cleaning. Following the execution of a small number of initially programmed washes, the computer selects the succeeding wash compositions. Presented at the 73rd AOCS annual meeting, Toronto, 1982.     

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.     

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.     

Lipid distribution on textiles in relation to washing with lipases

Effectiveness of lipase in detergency was studied using three test soils (lard, artificial sebum, and olive oil) on a woven cotton fabric. Distribution of oily soil on fabrics was determined for three different treatments (unwashed, washed with detergent without lipase, and washed with detergent plus lipase). Osmium tetroxide was used to label lipid soil for analysis in the scanning electron microscope. Both longitudinal and cross-sectional backscattered electron images for unwashed samples showed that soil was present on surfaces of the cotton fibers and in interfiber spaces of the yarn bundle. Lard soiled samples had large deposits on the fabric surfaces, while artificial sebum and olive oil appeared more uniformly distributed throughout the textile. Oil was deposited in the interfiber capillaries of the yarn bundle and in the crenulation, secondary walls, and lumen of the fibers. Energy dispersive X-ray microanalysis was used to determine relative concentrations of oil at selected morphological locations within the fiber structure and at the fiber surface. Soil distributions within the fibrous structures differed with type of soil and laundry treatment. Backscattered electron images dramatically demonstrated the effect of lipase on cleaning. After washing with detergent plus lipase, yarn surfaces had much less residual soil; residual soil that remained was in the irregularities of the cotton fiber surfaces. Concentrations of oil in the secondary walls, crenulations, lumen, and the fiber surfaces were lower after lipase treatment for all three soils. While washing with detergent removed soil from the yarn and fiber surfaces and the crenulation of the cotton fiber, only the samples washed with detergent plus lipase had lower concentrations of soils within the secondary wall and lumen of the cotton fibers. Fabrics soiled with olive oil and washed with detergent plus lipase had the lowest concentrations of residual soil across the textile structure; the residual soil observed was mainly in the irregularities on the fiber surfaces.     

Surfactants and protocols to induce spontaneous emulsification and enhance detergency

In this study the presence of an oil-soluble nonionic surfactant, Brij 30 (polyoxyethylene-4 lauryl ether), in an oil stain, or its addition to the stain through an oil-based solution or water-based mixture is shown to enhance, to a great extent, the spontaneous removal of the stain from a polyester fabric by inducing rollback and spontaneous emulsification phenomena. These findings lead to potential applications of Brij 30 as laundry pre-spotters for enhancement of the removal of tough stains. The effect of three key factors, namely, the surfactant type, the surfactant concentration, and the surfactant application protocol, on the effectiveness of spontaneous detergency was analyzed via ultraviolet-visible spectroscopy. The test fabrics were soiled with a stain composed of mineral oil plus orange OT dye [1-(o-tolylazo)-2-naphthol]. The results showed that all three factors were important for effective detergency. Brij 30 removed more than 80% w/w of the stain, whereas sodium dodecyl sulfate removed less than 24% w/w, and Brij 35 (polyoxyethylene-23 lauryl ether) was ineffective, removing less than 1% w/w. It was also observed that a low threshold concentration of Brij 30, approximately 0.2 mM, was required to spontaneously remove the oil stain, and that higher concentrations did not cause a significant enhancement of the effectiveness of soil removal. Brij 30 completed the detergency effect in less than 1 min, which may have beneficial implications regarding reduced energy consumption. Video microscopy studies revealed that at low Brij 30 surfactant concentrations, the mechanism for spontaneous oil removal proceeded predominantly via a rollback mechanism and that at higher concentrations, a spontaneous emulsification mechanism became progressively more important.     

PB/TAED对织物氧漂洗涤的损伤研究

采用含有PB/TAED活化氧漂体系的洗衣粉对活性染料上染的棉织物进行洗涤.设计正交实验,在不同染料、洗涤剂、温度等条件下测试织物洗后的拉伸断裂强力、K/S值、色差,得出各因素对织物性能的影响.为更好地进行织物护理提供依据.     

Role of virucides in controlling virus dissemination by fabrics

Vaccinia virus, a lipophilic agent containing deoxyribonucleic acid, and poliovirus, a hydrophilic ribonucleic acid virus, persisted on wool and cotton fabrics for varying periods up to 20 weeks, which was of sufficient duration to be of epidemiological significance. The length of persistence of each virus varied with the type of fabric, humidity and method of exposure to the virus. A group of quaternary ammonium salts and bromosalicylanilides were evaluated quantitatively for virucidal activity against these viruses in a cell culture system. None of the compounds was active against poliovirus, but three of the quaternary ammonium compounds significantly inactivated vaccinia virus. Impregnation of wool and cotton fabrics with one of these compounds resulted in a marked decrease in vaccinia virus persistence. Both polio and vaccinia viruses persisted for less than five days on a cotton fabric finished with a modified triazone resin to impart a wash-and-wear property. Cotton fabric contaminated with vaccinia or with poliovirus was laundered with an anionic detergent and a nonionic detergent. This laundering reduced but did not eliminate the virus. Sterile fabric was contaminated with virus when laundered with the virus-containing fabrics. Drying the fabrics for 20 hr after laundering reduced the virus titers to below detectable limits. Presented at the AOCS Meeting, New York, October, 1968.