Recovery of noble metals by the use of functional adsorber textiles

Recikliranje i oporaba skupih plemenitih metala, poput platine, zlata, paladija i srebra, odnosno rijetkih i strateških metala, poput indija, galija i rijetki zemljanih metala iz otpadnih metala i otpadnih voda dobit će na važnosti u sljedećih nekoliko godina. Stoga je potrebno usmjeriti pozornost na iznalaženje potenijalno korisnih sekundarnih izvora i razvoj jeftinih i energetski štedljivih postupaka kojima bi se selektivno razdvojili i oporabili metali (urbano rudarstvo). Zajedno s elektroničkim otpadom, industrijski procesi i otpadna voda predstavljaju značajan izvor plemenitih metala. Nedavno smo uspješno razvili inovativni tekstilni filtarski materijal za adsorpciju metala temeljen na poliesterkim vlaknima oslojenim polivinilaminom. Površinske modifikacije vlaknatog materijala lako je postići konvencionalnim metodama tekstilne dorade i tako dobiti trajno adsorpcijsko sredstvo visoke učinkovitosti, a istovremeno niske cijene. Naši se rezultati temelje na uobičajenim postupcima teksilne dorade i na adsorpciji iona plemenitih metala ovisnoj o pH vrijednosti. Provedivost čitavog postupka prikazana je na postupku obrade vode bogate paladijem, dobivene od jednog njemačkog proizvođača tiskanih ploča. Pored toga, isti inovativni adsorpcijski materijal može se koristiti za pročišćavanje površinskih voda i tla zagađenih kromatima. Najnovija istraživanja usmjerena su na korištenje ovog materijala za selektivnu oporabu rijekih zemljanih metala iz industrijske proizvodnje FCC katalizatora za naftnu industriju.The recycling and recovery of high-prized noble metals such as platinum, gold, palladium and silver or rare and strategic metals like indium, gallium, and rare earth metals from scrap metals and wastewaters will be from steadily increasing importance within the next years. Therefore, the focus has to be set on the detection of potentially usable secondary resources and the development of inexpensive and energy-saving processes to separate and recover the metals selectively (urban mining). Beside electronic scrap industrial process and wastewaters represent a considerable source for noble metals. Recently, we have successfully developed an innovative metal-adsorbing textile filter material based on polyvinylamine-coated polyester fibers. The surface modification of the fibrous material is easy to realize with common methods in textile finishing yielding a durable, high-performing and even cheap adsorbent for water-dissolved metal ions. We present results on the general textile finishing procedure and the pH-depending adsorption of noble metal ions. The feasibility of the overall process is demonstrated on palladium containing process waters obtained from a German producer of curcuit boards. Moreover, the same innovative adsorber material is useful for the decontamination of chromate-polluted ground waters and soils. Our latest investigations focus their use in the selective recovery of rare earth metals from large-scale FCC catalyst production for the petroleum refining industry

Preparation of a Textile-Based Dye-Sensitized Solar Cell

Solar energy conversion is an object of continuous research, focusing on improving the energy efficiency as well as the structure of photovoltaic cells. With efficiencies continuously increasing, state-of-the-art PV cells offer a good solution to harvest solar energy. However, they are still lacking the flexibility and conformability to be integrated into common objects or clothing. Moreover, many sun-exposed surface areas are textile-based such as garments, tents, truck coverings, boat sails, and home or outdoor textiles. Here, we present a new textile-based dye-sensitized solar cell (DSC) which takes advantage from the properties inherent to fabrics: flexibility, low weight, and mechanical robustness. Due to the necessary thermostability during manufacturing, our DSC design is based on heat-resistant glass-fiber fabrics. After applying all needed layers, the overall structure was covered by a transparent and simultaneously conductive protective film. The light and still flexible large-area devices (up to 6 cm2 per individual unit) are working with efficiencies up to 1.8% at 1/5 of the sun. Stability tests assure no loss of photovoltaic activity over a period of at least seven weeks. Therefore, our technology has paved the way for a new generation of flexible photovoltaic devices, which can be used for the generation of power in the mentioned applications as well as in modern textile architecture

Strukturbildung in dünnen Filmen aus Mischungen statistischer Copolymere

Dünne Polymerfilme besitzen einen weiten Anwendungsbereich in vielen High-Tech Applikationen. All diese Anwendungen erfordern ein bestimmtes Anwendungsprofil des dünnen Films. Diese Anforderungen umschließen sowohl die physikalischen Eigenschaften des Films als auch seine Struktur. Um sie zu realisieren, werden oftmals Mischungsfilme aus verschiedenen Polymeren verwendet. Diese neigen jedoch in vielen Fällen zur bereits während der Präparation zu Phasenseparation.Vor diesem Hintergrund wurde untersucht welchen Einfluss die Verträglichkeit der gemischten Polymere auf die Strukturbildung des dünnen Films ausüben. Als Modellsystem hierfür dienten Mischungen statistischer Poly-styrol- stat-para brom-styrol Copolymere.Die Oberflächenstrukturen, die sich währen der Präparation der Mischungsfilme einstellten, wurden mit Rasterkraftmikroskopie untersucht. wobei die Topologie einer statistischen Analyse unterzogen wurde. Zum einen wurde hierzu die spektrale Leistungsdichte der Oberflächenkontour zum anderen die zugehörigen Minkowski-Funktionale berechnet.Neben Oberflächenstrukturen bilden sich während der Präparation auch Entmischungsstrukturen im inneren des Filmes. Zur Charakterisierung dieser Strukturen wurden die Filme durch Streuung unter streifendem Einfall untersucht. Durch eine modellfreie Interpretation der Streuexperimente gelang der Nachweis der inneren StrukturenFür nur schwach unverträglich Filme konnte auf Basis der Streuexperimente eine Replikation der Oberflächenstruktur des Substrates auf die Filmoberflächen nachgewiesen werden. Diese Replikation wurde für verschieden raue Substrate und bezueglich der Kinetik ihrer Abnahme beim Quellen der Filme untersucht.Thin polymer films find widespread use in many high-tech applications. All these applications differ in their requirement profile, which entails the physical properties as well as lateral structures. In order to satisfy these requirements different polymers are often blended. In most cases this leads to a phase separation even during preparation.In order to investigate this phase separation, model systems consisting of binary blends from poly-styrene-stat-para-bromostyrene copolymers were investigated.The surface structures which evolved during the preparation process were characterised with scanning probe microscopy. In order to compare the topographies the SPM images were subjected to a statistical analysis in terms of the power spectral density and Minkowski functionals. Furthermore demixing structures are formed within the interior of the film as well. To investigate these structures grazing incidence small angle scattering experiments were conducted and analysed in a model free way.In the case of weakly incompatible binary polymer blend films interfacial correlation between the surface of the substrate and the free film surface were found. This roughness replication was investigated as a function of the blend composition and the substrate roughness. Furthermore the decay of the roughness correlation upon swelling under toluene atmosphere was investigated through kinetic measurements

Impregnability and Performance of rCF-nonwovens with epoxy resin

Temporarily the carbon fiber key market increases intensely. In consequence of production 10–30 % cost-intensive carbon fiber waste is accumulated by blending fabrics, prepregs which are out of specification and end-of-life products. Since a landfill ban for carbon fibers, environmental aspects and a cost reduction potential there is a stronger focus on carbon fiber recycling. [1] Through new recycling methods the carbon fiber is regained from polymer matrix, but lost its woven structure.One possibility to re-use chopped recycled fibers is through a fiber mat. Carbon fiber nonwovens can for example be fabricated by a wet-laid process. For recycled fibers without a specific fiber length and sizing there is the challenge to separate them in dispersion to get homogenous fleeces and interlink the fibers in the fleece. For the first step stirring and surfactants improve the separation [2], hydroxyethylcellulose ensures the bonding. Then the fleece can be impregnated with thermosets by resin transfer molding (RTM). The University of Applied Science Niederrhein as first investigates the whole process chain from handling recycled carbon fibers to get the finished composite. Optical impregnability is inspected and material properties (tensile strength and Young’s modulus) are analyzed and compared to virgin fibers to get information on performance. A density range from 1.18 (5% CF) to 1.4 g/cm³ (40% CF) is very attractive for lightweight constructions as well.Currently, the carbon fiber key market increases intensely. In consequence of production, 10–30 % of cost-intensive carbon fiber waste is accumulated by blending fabrics, prepregs which are out of specification and end-of-life products. Because of a landfill ban for carbon fibers, environmental aspects and a cost reduction potential, there is a stronger focus on carbon fiber recycling. Through new recycling methods, the carbon fiber is regained from polymer matrix, but looses its woven structure.One possibility to re-use chopped recycled fibers is through a fiber mat. Carbon fiber nonwovens can be fabricated by a wet-laid process, for example. For recycled fibers without a specific fiber length and sizing, a challenge lies in separating them in dispersion to get homogenous nonwovens and interlink the fibers in the nonwoven. For the first step, stirring and surfactants improve the separation, hydroxyethylcellulose ensures the bonding. Then the nonwoven can be impregnated with thermosets by resin transfer molding (RTM). The University of Applied Science Niederrhein is the first to investigate the whole process chain from handling recycled carbon fibers in order to attain the finished composite. Optical impregnability is inspected and material properties (tensile strength and Young’s modulus) are analyzed and compared to virgin fibers to get information on performance. A density range from 1.18 (5% CF) to 1.4 g/cm³ (40% CF) is very attractive for lightweight constructions as well

Dyeing of m-Aramid Fibers in Ionic Liquids

Aramids represent a class of high-performance fibers with outstanding properties and manifold technical applications, e.g., in flame-retardant protective clothing for firefighters and soldiers. However, the dyeing of aramid fibers is accompanied by several economic and ecological disadvantages, resulting in a high consumption of water, energy and chemicals. In this study, a new and innovative dyeing procedure for m-aramid fibers using ionic liquids (ILs) is presented. The most relevant parameters of IL-dyed fibers, such as tensile strength, elongation and fastness towards washing, rubbing and light, were determined systematically. In summary, all aramid textiles dyed in ILs show similar or even better results than the conventionally dyed samples. In conclusion, we have successfully paved the way for a new, eco-friendly and more sustainable dyeing process for aramids in the near future

Tuning the density of zwitterionic polymer brushes on PET fabrics by aminolysis : Effect on antifouling performances

Here, we synthesize zwitterionic polymer brushes on polyester fabrics by atom transfer radical polymerization (ATRP) after a prefunctionalization step involving an aminolysis reaction with ethylenediamine. Aminolysis is an easy method to achieve homogeneous distributions of functional groups on polyester fibers (PET) fabrics. Varying the polymerization time and the prefunctionalization conditions of the reaction, it is possible to tune the amount of water retained over the surface and study its effect on protein adhesion. This study revealed that the polymerization time plays a major role in preventing protein adhesion on the PET surface