Erhöhung der Energieeffizienz der Crossflow‐Filtration durch keramische Rohrmembranen einer neuen Generation

The effect of cross‐flow filtration of liquids relies on the continuous and controlled circulation of fluids in linear channels. The flow rate is of crucial importance to the economy of the process. TAMI Industries is investigating the use of so‐called additive processes to produce ceramic supports with geometric structures that cannot be produced using traditional technologies. In comparison to conventional geometries, it is possible to increase the permeate output without increasing the energy consumption or correspondingly reducing the energy consumption at the same permeate output.     

Surface modification of a novel porous titanium dioxide/glass composite

A novel technique is used to produce an open porous titanium dioxide/glass composite, named Ecopore, with promising structural and biological properties for the development as a bone graft. This study aims at a fast and lasting integration of the new material by means of biochemical surface modification. Surface etching of Ecopore, aminosilanization and covalent coupling of the cellular attachment mediator fibronectin was employed as modification strategy. In a comparison of different etching procedures, alkaline etching led to the highest density of amino functions after subsequent aminosilanization. Fibronectin was immobilized using a bifunctional aminoreactive PEG‐linker. This protein coating improved the attachment of human osteoblast‐like cells (HOB) on non‐porous Ecopore as displayed by vital staining. XTT metabolism assays indicated an enhanced HOB growth in the initial phase of cultivation on fibronectin‐coated versus non‐coated specimens. In a first feasibility study, cultivation of HOB on coated porous Ecopore cylinders with a median pore size diameter of 130 μm showed that cellular growth was uniform and dense on the external surface of the specimen, but was sparse in the interior pore system. Ecopore batches with larger pores will be modified and investigated in vitro and in vivo in the next step of the study.     

Keramische Membranen in der Membrandestillation

TiO₂ membranes were successfully rendered hydrophobic (modified with perfluoroalkyl silanes) and evaluated by liquid entry pressure (LEP) measurements and membrane distillation (MD) tests. It was shown that the LEP is strongly depended on the pore size of the membranes and the feed composition. The obtained permeate fluxes were highest in vacuum MD. None of the membranes showed any sign of wetting during the experiments and salt retentions greater than 99.9 % were recorded and permeate qualities lower than 2 µS cm^?1 were achieved in air gap MD and vacuum MD.     

Controlled adsorption of titanium(IV) oxide particles on electroplated zinc coatings to improve the corrosion resistance of chromium(VI)‐free conversion layers

Adsorption of nano‐scaled titanium(IV) oxide particles on electroplated zinc is performed by a simple dip‐coating technique in an aqueous titanium(IV) oxide suspension prepared with a stirred media mill. X‐ray photoelectron spectroscopy, scanning electron microscopy and X‐ray fluorescence spectroscopy are carried out to investigate the composition of the zinc surface and the thickness and porosity of the adsorbed titania films. The zinc surface formed during the electrodeposition process is of oxyhydroxide nature and the thickness of the adsorbed titania particle layer is controlled by the pH value and the solid concentration of the suspension. In the range of 10 wt.%–30 wt.% titanium(IV) oxide, a linear dependence between the titania film thickness and the solid content of titania particles in the suspension is found. Highest film thicknesses are obtained in alkaline media (pH≥9). At 13.5 wt.% titania particles and pH values below pH = 2.4, the titania particle film is not closely packed and the zinc layer underneath is still visible in electron microscopy, which is a prerequisite for imbedding these particles by a thin second zinc layer for formation of a robust chromium(VI)‐free passivation layer containing the titania particles.     

Nanokristalline Werkstoffe hergestellt mit dem Thermischen HF‐Plasma

Nano‐crystalline materials manufactured with the Thermal RF‐Plasma The Inductively Coupled Plasma (ICP) at atmospheric pressure is particularly suited for melting and evaporation of materials. The electrodeless ICP can be generated without limitation of the kind of plasma forming gases. Therefore, using an argon‐oxygen gas mixture as sheath gas of the ICP nanophase coatings can be processed by synthesis with metal‐organic liquid precursors injected in the hot plasma core. For depositions, the plasma jet has to be supersonic. For particles which impinge onto the substrate placed near the nozzle exit of the plasma torch thin and dense coatings are obtained with crystallite sizes of 30‐ 40 nm. The composition and the grain size of as‐deposited coatings are analyzed by XRD.     

Sol‐Gel Synthesis and Spray Granulation of Porous Titania Powder

Bimodale poröse Titandioxidpulver mit kontrollierter Phasenzusammensetzung und ‐porosität, die nasschemisch hergestellt wurden, sind in unserem Labor umfassend untersucht worden. Diese Arbeit gibt eine Übersicht über experimentelle Parameter, die die Phasen‐ und Porenstruktur dieser Pulver beeinflussen. Außerdem wird der Einfluss von Lösungspeptisation auf die Packung und Anordnung der Partikel untersucht. Die unpeptisierte Sprühlösung und das peptisierte Sol wurden sprühgetrocknet, um Granulate mit kontrollierter Porosität und Morphologie herzustellen. Die Eigenschaften der Granulate waren abhängig von den Eigenschaften der verwendeten Lösung. Insbesondere die Granulate aus der unpeptisierten Sprühlösung zeigten eine bimodale Porengrößenverteilung mit rauen Oberflächen, die auf harte Aggregate zurückzuführen sind. Granulate vom peptisierten Sol zeigten eine monomodale Porengrößenverteilung mit glatten Oberflächen von gutgepackten Mikrostrukturen. Potentielle Anwendungen ergeben sich für diese Granulate als Adsorber, als Katalysatorträger und als Packung für chromatographische Trennkolonnen.     

Gasphasensynthese von Kern/Mantel‐Partikeln am Beispiel von TiO2‐Nanopartikeln mit elektrisch leitendem Mantel

An advanced process enables synthesis and coating of individual TiO₂‐core particles with a shell of transparent conducting oxide (TCO) from the gas phase in one reactor. TiO₂ particles were coated with fluorine‐doped tin oxide (SnO₂:F) or antimony‐doped tin oxide (SnO₂:Sb). Specific electrical conductivity of the core/shell particles was up to 8 · 10^–3 S cm^–1. Variation of process parameters allows modifying dopant level and conductivity in an easy way.     

Characterisation of the mechanical properties of polyamide 12 powder when using titanium dioxide as antimicrobial additive

Antimicrobial properties of plastic components are an important part of polymer engineering. One commonly used additive with an antibacterial effect is titanium dioxide. The aim of this study is to investigate the influences on the mechanical properties resulting from the addition of titanium dioxide as an antimicrobial additive and the processing of the compounds with selective laser sintering. Compounds with 5 %, 10 % and 15 % titanium dioxide and polyamide 12 as matrix material are fabricated. Tensile test specimen are produced from the compounds, examined and the results compared with virgin polyamide 12. The investigations show a general loss in the ultimate tensile strength compared to the virgin polyamide 12. Comparing the different titanium dioxide contents with each other, an increasing tensile strength with increasing titanium dioxide content of the compound can be examined. A decreasing elongation at break and thus a decreasing ductility can also be observed. Furthermore, the results of the tensile test show a stiffening effect, i. e. an increase in the elastic modulus due to the addition of titanium dioxide.