Particulate Soil Removal Research Articles

Cleaning Efficiency of Amino-Acid Surfactants with Polyoxyethylene Ether and Isopropanol in Liquid Carbon Dioxide

Although anionic surfactants have a distinct positive influence on the removal of particulate soil, the removal of particulate soils is insufficient in CO2 compared to perchloroethylene. A series of amino-acid surfactants was selected as main surfactants to study the influence of polyoxyethylene ether and cosolvent on the cleaning effect. Glu-C12 and C16(3) gave the best cleaning results, which increased from a detergency value of 4.6 when no surfactants were used to 8.32 when surfactants were used. In all experiments, charged anionic surfactant particles were formed, which are responsible for the removal of particulate soil from fabric by electrostatic repulsion. The use of a cosolvent (Isopropanol [IPA]) had a positive effect on the removal of particulate soil when using Glu-C12 and TX-45. However, for other compounding combinations, the addition of IPA had a negative effect on particulate soil removal. Of the cosolvents investigated, IPA was the most suitable. With the polarity of the system increasing after adding IPA, the ethylene oxide groups of TX-45 were partially extended to CO2. Through the steric effects of branched methyl groups, the cleaning effect was improved.

Structural disjoining pressure induced solid particle removal from solid substrates using nanofluids

Nanofluids comprising nanoparticle suspensions in liquids have significant industrial applications. Prior work performed in our laboratory on the spreading of a nanofluid on a solid substrate has revealed that the structural disjoining pressure gradient caused by the layering of the nanoparticles normal to the confining plane of the film with the wedge profile is a new mechanism for oily soil detachment from the solid substrate. In the present work, we explore the application of this new mechanism for the solid particle detachment using latex particles on glass and a copper-coated wafer substrate using nanofluids. In the experiment, we employed the nanofluids to observe the detachment of the latex particles adhered to the glass substrate.We found that the structural disjoining pressure exerted by the nanoparticles can detach the solid particles on the glass substrate. A video depicting this mechanism is provided. Our results showed that the detachment of the particulate solid particles on the solid substrate was clearly enhanced by the nanofluids, compared to using only pure liquids (such as water). The detachment efficiency was increased with the increase in the nanoparticle volume fraction.Our nanofluids also showed a greater detachment efficiency for the particulate soil removal from the copper-coated wafer substrates compared to that of pure liquids.We found that the detachment efficiency is well correlated with the calculated structural disjoining energy.Our findings in this paper provide new insights for the novel application of the structural disjoining energy mechanism for cleaning hard surfaces.

Correlation analysis between particulate soil removal and surface properties of laundry detergent solutions

The purpose of this study is to correlate surface properties of laundry detergents and model surfactant solutions with their washing abilities. For the study, laundry detergents available on the Polish market were selected and categorized according to their retail price: the cheapest ( P1, P2, P3), average priced ( P4, P5, P6, P7, P8) and the most expensive ( P9, P10). Anionic sodium dodecylbenzenesulfonate and nonionic nonaethylene glycol monodecyl ether were used for the preparation of the model solutions. The content of the anionic and nonionic surfactants in the detergents was determined. Cotton fabrics were soiled with black carbon/olive oil, make-up, curry, red wine, tomato sauce, blood, chocolate, peat, tea, β-carotene, grass, animal fat/red dye, baby food, clay, butter and used engine oil. Detergency tests were carried out at a temperature of 40℃ in laboratory conditions using washing powders and model surfactant solutions in various concentrations. On the basis of the correlation between detergency and detergent properties, the most favorable size range of powder granules was identified. The negative correlation between contact angle, surface tension and detergency and the positive relationship between phosphorus pentoxide and active oxygen content, spreading coefficient, diffusion coefficient and detergency were determined. The closest correlation between surfactant content and detergency was observed at a concentration of 10 g/L, which resulted in maximum detergency. When the emulsifying properties were better, their soil removal efficiency was greater. Based on the analysis of the correlation, the characteristics of the tested laundry detergent solutions that had the greatest ability to remove dirt were described.

CO2 dry cleaning: Acoustic cavitation and other mechanisms to induce mechanical action

High pressure carbon dioxide (CO2) is a potential solvent for textile dry cleaning. However, the particulate soil (e.g. clay, sand) removal in CO2 is generally insufficient. Since cavitation has been proven to be beneficial in other CO2 cleaning applications, this study aims to investigate the possibility of improving the performance of CO2 textile dry cleaning by using ultrasound or other mechanisms to induce the mechanical action such as bubble spray and jet spray. In the experiments, several types of textiles soiled with a mixture of motor oil and soot were cleaned using 1L and 90L CO2 dry cleaning set-ups. Using either ultrasound, stirring, liquid spray or bubble spray does not give a significant improvement on particulate soil removal from textile. It was also found that the additional use of ClipCOO detergent does not give a significant improvement on particulate soil removal either. The cleaning performance of CO2 is 50% lower than that of PER and thus another method to increase the particulate soil removal in CO2 textile dry cleaning still needs to be developed.

Mechanical action in CO2 dry cleaning

High-pressure carbon dioxide (CO2) is a potential alternative for perchloroethylene (PER), a common but harmful textile dry cleaning solvent. Previous studies have indicated that the particulate soil removal with CO2 is lower compared to that with PER, because of the low amount of mechanical action in CO2. It is the objective of this study to get more insight in the influence of various types of mechanical action on the cleaning results in CO2 dry cleaning. In the experiments, various mechanisms of mechanical action, such as rotating drum, CO2 spray, and ultrasound were investigated. Several types of textiles stained with different kinds of particulate soils were cleaned using 25L and 90L CO2 dry cleaning set-ups. The washing results show that liquid CO2 spray may be a suitable additional mechanism to provide textile movement. The average CPI of CO2 over all soils using the best combination of commercial machine and process was still 25% lower than the results with PER and 18% lower than the results with water, but 11% higher than K4 solvent while the average redeposition level was significantly lower, showing that CO2 has a good prospect as an alternative solvent to replace PER. An endoscopic camera has been installed in the 25L set-up to get an insight in the textile movement inside the rotating drum. The results show that no plug formation occurs and the textile movement in CO2 is sluggish, which means that the mechanical movement of textile in CO2 dry cleaning does not follow the simplified tumbling-movement model which was developed in a previous study, and the mechanical action is much less than predicted.

Redeposition in CO2 textile dry cleaning

Perchloroethylene (PER) is commonly used as cleaning solvent in the textile dry-cleaning industry but this chemical is toxic by nature. One of the potential PER replacements is carbon dioxide (CO2), which is non-toxic, cheap, and widely available. Previous studies have indicated that the particulate soil removal with CO2 is lower compared to that of PER. While the particulate soil removal of the CO2 dry-cleaning was studied, it was found that redeposition of particulate soil occurs. Several experiments have been carried out to study and reduce this problem. In these experiments, textiles stained with different kinds of particulate soils were cleaned using a 25L CO2 dry-cleaning set-up. It was found that the redeposition level increases along with washing time, while rinsing has little influence. Modifying the filtration system by using scavenger textile, or adding a cellulose compound to the cleaning vessel as anti redeposition agent can significantly reduce redeposition.

Towards detergency in liquid CO2 – A surfactant formulation for particle release in an apolar medium

In this paper we propose, characterize and test a surfactant formulation, consisting of a branched polyoxyethylene type commercial non-ionic surfactant (Igepal CA520), n-hexane and water, for use in CO2 dry-cleaning to enhance the removal of particulate soil. In the formulation lamellar mesophases Lα coexist in an L2 microemulsion (reverse micellar) phase. We hypothesize that enhanced soil removal would be possible due to the adsorption of lamellar liquid crystalline phases at the fabric–soil interface, the presence of water pools, the improvement of the solvent quality of liquid CO2 by the presence of n-hexane, and the enhanced viscosity due to the presence of the lamellar mesophases. We have characterized the formulation by optical microscopy with crossed polarizers, confocal microscopy, dynamic light scattering and shear viscometry to determine the phase behaviour, the size of the reverse micelles and the flow behaviour. AFM force measurements in n-hexane show that large adhesion forces between a model soil particle (silica) and fabric surface (cellulose) in water-saturated hexane can be reduced by the action of the surfactant mesophases. In the presence of the surfactant formulation the interaction forces were found to be decreased from ∼15nN to 0.5nN. The formulation, applied as a pre-treatment on standard soil test monitors and followed by washing in liquid CO2, showed a five times better soil removal ability than the control.

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

AbstractIn 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.

Amino acid based surfactants for dry-cleaning with high-pressure carbon dioxide

The currently most used dry-cleaning solvent is perchloroethylene (PER). Carbon dioxide could be an ideal solvent to replace PER. Amino acid based surfactants have been studied for dry-cleaning with carbon dioxide. For the production of amino acid based surfactants, renewable, low-cost raw materials are used. Furthermore, these surfactants have a low toxicity, are biodegradable and not skin irritating. These characteristics make the amino acid based surfactants attractive for dry-cleaning with carbon dioxide. The amino acid based surfactants give good results for dry-cleaning with liquid CO 2. The surfactant Amihope LL ( N-lauroyl- l-lysine) gives the best cleaning-results. An important process parameter using this surfactant is the addition of water. The addition of water is required for sufficient removal of non-particulate soils. However, when no water is added to the system, there is a large increase in particulate soil removal. Therefore, a two-bath process is proposed. The first bath is for particulate soil removal and has optimal conditions for particulate soil removal; the second bath has optimal conditions for non-particulate soil removal. The two-bath process using Amihope LL gives excellent results: the result for particulate soil removal is 84% compared to the results for PER, the result for non-particulate soil removal is 98% compared to PER and the overall result is 92% compared to PER.

Surfactants for particulate soil removal in dry-cleaning with high-pressure carbon dioxide

The removal of particulate soils from textile in dry-cleaning with CO 2 is insufficient compared to perchloroethylene (PER). Especially the removal of relatively small particles (<20 μm) poses a problem. Various anionic and amine based surfactants have been investigated to enhance the removal of particulate, but also of non-particulate soils in dry-cleaning with high-pressure CO 2. The cleaning performance index for relatively small particulate soil (CPI part) increased from 24% (when no surfactants were used) to a maximum of 51% (when surfactants were used), which shows that particle removal is possible in CO 2 dry-cleaning. The use of these surfactants, however, does not bring particle removal up to the level of PER (CPI part of 68%). The removal of non-particulate soils in CO 2 with water, surfactant and co-solvent is better than in PER. The overall results using the investigated surfactants are promising; the overall result increases from 70% (when no surfactants are used) to 87% (when surfactants are used) compared to the level when using PER. Surfactant particles were formed in all experiments. In the case of the amines, these particles may be formed by reaction. The formed charged surfactant particles are probably responsible for the removal of the soil particles from the textile. The charged surfactant particles may adhere to the soil particles and/or fabric, thereby establishing an element of repulsion and/or a steric barrier. The use of a co-solvent (iso-propanol) had a positive effect on the removal of particulate and non-particulate soils when using amines. However, when anionic surfactants were used, the addition of a co-solvent had a pronounced negative effect on particulate soil removal.

Dry-cleaning with high-pressure carbon dioxide—the influence of mechanical action on washing-results

Previous studies indicate that the removal of non-polar soils in CO 2 is comparable to the level of dry-cleaning in perchloroethylene (PER). However, these studies show that the removal of particulate soil is insufficient in CO 2 compared to PER. Particle removal can be increased by the use of more mechanical action and/or the use of surfactants. From experiments, it is concluded that the removal of relatively large particles like sand increases with increasing mechanical action. However, the level of mechanical action has no influence on the removal of relatively small particulate and non-particulate soils (with the exception of clay on wool). Increasing the amount of mechanical action is therefore not the solution that will lead to the increase of the washing-results for relatively small particles (like carbon black and clay) up to the level of the washing-results using PER. The removal of relatively small particulate soils in CO 2 can be improved by the use of suitable surfactants that reduce adhesion forces. A model for quantifying the amount of mechanical action has been developed. This model can be used to predict the optimal process conditions for relatively large particle removal. It is concluded (from the model and experiments) that the level of highest mechanical action in CO 2 is obtained in a two-phase environment at low pressure and temperature and that 75 RPM is the optimal number of revolutions in our system. At these conditions, however, the washing-results for small particles are not as good as the washing-results for these particles in PER.

Detergency Study: Comparison of the Distribution of Natural Residual Soils After Laundering with a Variety of Detergent Products

Five commercial laundry detergents were evaluated using natural soil obtained from facial wipes. The largest observed difference between products was in their removal of particulate soil from the yarn surfaces. The effectiveness of particulate soil removal was related to the surfactant/builder system, with the phosphate built, anionic powdered detergent being the most effective, and the built liquids being more effective than the unbuilt liquid detergents. For all detergent products tested, electron beam x-ray mi croanalysis indicated that the largest percentage of residual oil was located in the interfiber capillaries of the yarn structure, followed by the secondary walls, the lumen, and the crenulation of cotton fibers. Little or no oil was observed in the interior of polyester. The large variation in soil level between facial wipes prepared by different panelists had an effect on the concentration of the oil within the fibrous structures. The type of laundry detergent used also influenced the concentration of residual oily soil found in selected locations within and around the cotton and polyester fibers. Fiber surfaces retained less oil when the fabrics were laundered with the powdered detergents than when washed with the liquid detergents, but there were no differences in performance between the liquid and powdered detergents in removing oil from the lumen, crenulation, or secondary walls of cotton. The phosphate built powdered de tergent with anionic surfactants removed oily and particulate soil from yam surfaces more completely than the carbonate built powdered detergent with nonionic surfac tants. In comparison, the distribution of residual oil within the yarn structure was the same after laundering with the two powdered detergents. The citrate built liquid had higher concentrations of residual oil in the crenulation of the cotton fiber and on the fiber surfaces than the other liquid detergents. Since the differences between products were small, it appears that the factors limiting the detergency of oil from fabric structures are the same for all the detergent products evaluated.

Studies on the Removal of Particulate Soil. II

Studies on the Removal of Particulate Soil. II

Studies on the Removal of Particulate Soil. I.

Studies on the Removal of Particulate Soil. I.

The Effect of Wash Temperature on Removal of Particulate and Oily Soil from Fabrics of Varying Fiber Content

In the laundry process relatively high wash temperatures have traditionally been used for optimum soil removal. The use of lower wash temperatures could result in a substantial reduction in the amount of energy used in laundering. One of the purposes of this study was to determine soil removal at a range of wash temperatures with detergents of different formulations from cotton, polyester, and cotton/polyester fabrics. A second purpose was to evaluate the use of x-ray fluorescence analysis as a quantitative measure for determining particulate soil removal from fabrics. The samples were soiled by application of clay and either unlabeled or doubly-labeled synthetic sebum. Removal of oily soil was determined by measuring the radioactivity of the samples. Clay removal was measured by x-tay fluorescence analyses of iron and silicon, and overall soil removal was measured by changes in reflectance. Both clay and oily soil appeared to be best removed from cotton fabrics by higher wash temperatures. Low wash temperatures were best in removing the nonpolar fraction (triolein) of oily soil from polyester. Use of phosphate-built anionic detergents generally resulted in better soil removal than other types, regardless of wash temperature. Wash temperatures as low as 10°C gave acceptable soil-removal levels. Iron content varied with clay-particle size, thus silicon was the preferred indicator of clay content of fabrics.

Mechanisms of Soil Release

The detergency mechanisms for oily (liquid) soils and particulate soils are different. The functioning of a soil-release finish depends therefore on several of its properties. Oily-soil detergency involves diffusion of water to the soil-fiber interface and roll-up of soil. Other mechanisms (solubilization, emulsification, soil penetration, etc.) usually do not determine the rate of soil removal. Soil-release agents increase the hydrophilic ity of the fiber surface and enhance diffusion of water and hydration of the soil-fiber interface. Detergency of particulate soil is not dominated by the hydrophilicity of the fibers but depends on the location of the particle and its adhesion to the fiber surface. Soil-release agents can facilitate removal of particulate soil by decreasing adhesion of the soil particles and enhancing diffusion of water and detergent into the particle-fiber interface. Nondurable release agents also release particulate soil by a sacrificial flaking or dissolution mechanism. Problems encountered with soil removal from durable-press finished cotton and possible solutions are discussed.

Limitations in Studying the Kinetics of Fabric Detergency

The simplest expressions for the rate of removal of particulate soil from fabrics, including those for first-order kinetics, are described. Two factors militate against obtaining proportionality constants between a time function and a residual soil function which remain constant for long washing times, namely: redeposition, and heterogeneities in soil and fabric. Soil redeposition tends to lower the observed soil-removal rate. This effect can be eliminated by suitable experimental procedures. However, the inhomogeneities inherent in fabrics (fiber surface irregularities, variation in spaces between fibers and yarns) cause them to have sorption sites with a broad range of soil binding strengths. Variations in the size and shape of particles on artificial test fabrics and, for natural soil, in chemical composition as well, cause the particles to adhere to fabric substrates with bonds of different strengths. These heterogeneities produce a broad range of specific soil-removal rates whose values depend on the energies of adhesion of the particle-fabric complex. The most loosely held soil, with the highest removal rate constants, is washed off early so that the soil remaining on the fabric becomes progressively richer in the most tightly bound soil, with the smallest removal rate constants. Hence the average or observed rate constant for soil removal decreases during the washing process.

Particulate Soil Removal in Multiple Bath Systems

Particulate Soil Removal in Multiple Bath Systems