Köser, Joachim
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Joachim
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Köser, Joachim
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- PublikationAn origami 3D patterned cellulose-based scaffold for bioengineering cardiovascular applications(Springer, 2023) Gullo, Maurizio; Melo Rodriguez, Gabriela; Trueb, Donata; Schoelkopf, Joachim; Köser, Joachim [in: Cellulose]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationImproved phosphoric acid recovery from sewage sludge ash using layer-by-layer modified membranes(Elsevier, 01.10.2019) Paltrinieri, Laura; Remmen, Kirsten; Müller, Barbara; Köser, Joachim; Wintgens, Thomas [in: Journal of Membrane Science]We report an advanced treatment method for phosphoric acid recovery from leached sewage sludge ash. Layer-by-layer (LbL) polyelectrolyte deposition has been used as a tool to modify and convert a hollow ultrafiltration membrane into a nanofiltration (NF) LbL membrane for H3PO4 recovery. To build the LbL membrane, poly(styrenesulfonate) PSS was chosen as polyanion, while three different polycations were used: a permanently charged polyelectrolyte, poly(diallyldimethylammonium chloride), PDADMAC; a pH-dependent charged polyelectrolyte poly(allylamine hydrochloride), PAH; and a PAH modified with guanidinium groups (PAH-Gu). Based on detailed surface characterizations (AFM, XPS and Zeta-potential) it was concluded that both charge density and pH-responsiveness of the polycations are key parameters to control the final membrane surface structure and transport properties. The surface properties of LbL-coated membranes were correlated with the membrane filtration performance, when exposed to the real leached sewage sludge ash solution. The highest permeability was recorded for (PDADMAC/PSS)6, a result that was rationalized on its loose, and possibly less interpenetrated, structure, followed by (PAH-Gu/PSS)6 characterized by a more dense, compact layer. H3PO4 recovery was the highest in the case of (PDADMAC/PSS)6, but the retention of multivalent metals (Fe3+ and Mg2+) was low, leading to a more contaminated permeate. The opposite trend was observed for (PAH-Gu/PSS)6, resulting in a less metal-contaminated, but also a less H3PO4-concentrated permeate. Our LbL-modified membranes were found to improve the permeability and H3PO4 recovery compared to a commercially available acid-resistant NF membrane.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationPhosphorus recovery in an acidic environment using layer-by-layer modified membranes(Elsevier, 15.07.2019) Remmen, Kirsten; Müller, Barbara; Köser, Joachim; Wintgens, Thomas [in: Journal of Membrane Science]Phosphorus (P) is a limited natural resource and essential for global food supply, particularly given our ever-growing world population. However, natural P deposits are restricted to just a few countries and the quality of exploited primary sources is declining. Phosphorus recovery from sewage sludge or sewage sludge ash leached by acids is hence gaining importance. During P recovery the removal of impurities is a challenge that can be addressed by nanofiltration retaining e. g. multivalent metals and allowing phosphoric acid to pass. However, currently available membranes show low permeability and limit this process option economically. Layer-by-layer (LbL) membrane synthesis is a technology that allows membrane performance to be tailored to individual filtration tasks. Little is known for such membranes with respect to acid resistance, acid permeability and impurity rejection. We show that LBL membranes based on PDADMAC/PSS show the desired passage of phosphoric acid with retentions values below 10%, aluminum retention was always above 95%. Permeabilities up to 4 L/(m2 h bar) were reached even up to a phosphorous recovery of 75%. Overall permeabilities were 16 times higher than a commercial benchmark membrane. Initial stability tests and upscaling into a larger module show the viability of the proposed modification approach.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationAntimicrobial Polyethylene through Melt Compounding with Quaternary Ammonium Salts(Hindawi Publishing Corporation, 04/2017) Rossetti, Fernanda; Siegmann, Konstantin; Köser, Joachim; Wegner, Irene; Keskin, Ismail; Schlotterbeck, Götz; Winkler, Martin [in: International Journal of Polymer Science]Selected mono- and bicationic quats were compounded with polyethylene. The physicochemical surface properties, leaching behavior, and antibacterial activity of such modified samples were investigated. Contact angle measurements and fluorescein binding assays showed the presence of quaternary ammonium groups at the surface. After storing the samples in 50°C warm water for 30 days, several were still antimicrobially active. No correlation between the number of exposed N+ head groups after leaching and the antibacterial activity was observed. There is however a qualitative correlation of the antibacterial activity with the contact angles and surface concentrations of N+ before leaching/storing in warm water.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationReduced Adhesion of E.coli on Nanostructured Polycarbonate Surfaces(08/2016) Grether, Yasmin; Waser, Marcus; Köser, Joachim06 - Präsentation
- PublikationPlasma-Etched Nanostructured Polycarbonate Surfaces for Reduced Adhesion of E.coli bacteria(30.06.2016) Grether, Yasmin; Waser, Marcus; Pieles, Uwe; Köser, JoachimPlasma-etching represents a facile approach to nanostructure polymer surfaces. Here we report on the antibacterial properties of plasma-structured polycarbonate (PC)surfaces. PC foils were structured with O2 plasma and incubated with E.coli. Metabolic activity of adhered live bacteria was quantified with resazurin metabolic indicator. Different incubation times under shaking/resting conditions diminished metabolic activity on structured versus unstructured PC, indicating reduced bacterial adhesion on structured surfaces. Furthermore chemical surface modifications increased metabolic activity on structured compared to unstructured surfaces. Further research on other polymers will be done to analyse the generality of these observations.06 - Präsentation
- PublikationComparing the antimicrobial activity of different commercially available cationic polymers(30.06.2016) Köser, Joachim06 - Präsentation
- PublikationTargeting selective cell response by topographical structuring of resorbable polymer implants(06/2016) Köser, Joachim; Bruggisser, Urs; Beck, Stephan; Kristiansen, Per Magnus06 - Präsentation
- PublikationAntibacterial Active Glass(25.02.2016) Köser, Joachim; Pieles, Uwe; Meier, Pascal; Widmer, A.06 - Präsentation
- PublikationStimulus Dependent Flow through Polymer Modified Filtration Membranes(2016) Köser, Joachim; Pieles, Uwe06 - Präsentation