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Sutanto S.,Technical University of Delft | Van Roosmalen M.J.E.,Feyecon Carbon Dioxide Technologies | Witkamp G.J.,Technical University of Delft
Journal of Supercritical Fluids

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 25 L 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. © 2013 Elsevier B.V. All rights reserved. Source

Muller D.,Swiss Center for Electronics and Microtechnology | Muller D.,ETH Zurich | Cattaneo S.,Swiss Center for Electronics and Microtechnology | Meier F.,Postnova Analytics GmbH | And 8 more authors.
Journal of Chromatography A

We demonstrate the use of inverse supercritical carbon dioxide (scCO2) extraction as a novel method of sample preparation for the analysis of complex nanoparticle-containing samples, in our case a model sunscreen agent with titanium dioxide nanoparticles. The sample was prepared for analysis in a simplified process using a lab scale supercritical fluid extraction system. The residual material was easily dispersed in an aqueous solution and analyzed by Asymmetrical Flow Field-Flow Fractionation (AF4) hyphenated with UV- and Multi-Angle Light Scattering detection. The obtained results allowed an unambiguous determination of the presence of nanoparticles within the sample, with almost no background from the matrix itself, and showed that the size distribution of the nanoparticles is essentially maintained. These results are especially relevant in view of recently introduced regulatory requirements concerning the labeling of nanoparticle-containing products. The novel sample preparation method is potentially applicable to commercial sunscreens or other emulsion-based cosmetic products and has important ecological advantages over currently used sample preparation techniques involving organic solvents. © 2016 Elsevier B.V. Source

Banerjee S.,Wageningen University | Sutanto S.,Technical University of Delft | Kleijn J.M.,Wageningen University | Van Roosmalen M.J.E.,Feyecon Carbon Dioxide Technologies | And 2 more authors.
Advances in Colloid and Interface Science

Liquid CO 2 is a viable alternative for the toxic and environmentally harmful solvents traditionally used in dry-cleaning industry. Although liquid CO 2 dry-cleaning is being applied already at a commercial scale, it is still a relatively young technique which poses many challenges. The focus of this review is on the causes of the existing problems and directions to solve them. After presenting an overview of the state-of-the-art, we analyze the detergency challenges from the fundamentals of colloid and interface science. The properties of liquid CO 2 such as dielectric constant, density, Hamaker constant, refractive index, viscosity and surface tension are presented and in the subsequent chapters their effects on CO 2 dry-cleaning operation are delineated. We show, based on theory, that the van der Waals forces between a model soil (silica) and model fabric (cellulose) through liquid CO 2 are much stronger compared to those across water or the traditional dry-cleaning solvent PERC (perchloroethylene). Prevention of soil particle redeposition in liquid CO 2 by electrostatic stabilization is challenging and the possibility of using electrolytes having large anionic parts is discussed. Furthermore, the role of different additives used in dry-cleaning, such as water, alcohol and surfactants, is reviewed. Water is not only used as an aid to remove polar soils, but also enhances adhesion between fabric and soil by forming capillary bridges. Its role as a minor component in liquid CO 2 is complex as it depends on many factors, such as the chemical nature of fabrics and soil, and also on the state of water itself, whether present as molecular solution in liquid CO 2 or phase separated droplets. The phenomena of wicking and wetting in liquid CO 2 systems are predicted from the Washburn-Lucas equation for fabrics of various surface energies and pore sizes. It is shown that nearly complete wetting is desirable for good detergency. The effect of mechanical action and fluid dynamic conditions on dry-cleaning is analyzed theoretically. From this it follows that in liquid CO 2 an order of magnitude higher Reynold's number is required to exceed the binding forces between fabric and soil as opposed to PERC or water, mainly due to the strong van der Waals forces and the low viscosity of CO 2 at dry-cleaning operational conditions. © 2012 Elsevier B.V. Source

Sutanto S.,Technical University of Delft | Van Roosmalen M.J.E.,Feyecon Carbon Dioxide Technologies | Witkamp G.J.,Technical University of Delft
Journal of Supercritical Fluids

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 25 L and 90 L 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 25 L 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. © 2013 Elsevier B.V. All rights reserved. Source

Kuiper S.,Technical University of Delft | Embrechts A.,Saxion University | Every H.A.,Feyecon Carbon Dioxide Technologies | De Vries T.,Feyecon Carbon Dioxide Technologies | De Smet L.C.P.M.,Technical University of Delft
Macromolecular Materials and Engineering

This paper reports on a temperature-controlled, solution-based method to prepare diamine crosslinked Matrimid aerogels. Addition of a diamine to a preheated polymer solution resulted in a well-dispersed solution, allowing formation of a homogeneous gel upon cooling. The gels (studied by FTIR and AFM) were dried by solvent extraction with supercritical CO2. The resulting aerogels showed surface areas of approximately 150 m2. g-1 and porosities of 0.66-0.69 mL. g-1 with polymer domains and pore sizes of tens of nanometers. A room temperature- prepared, inhomogeneous aerogel gave approximately 250 m2 . g-1 and 0.31 mL. g-1with meso- and micropores. SEM images of the aerogels show similar surface features as AFM images of the Matrimid solvent gels. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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