Matthias Wessling | RWTH Aachen University (original) (raw)

Uploads

Papers by Matthias Wessling

Membranes, 2020

Nanofiltration (NF) can enable P recovery from waste streams via retaining multivalent impurities... more Nanofiltration (NF) can enable P recovery from waste streams via retaining multivalent impurities from spent pickling acid. However, with the currently available membranes, an economically feasible process is impossible. Layer-by-layer modified NF membranes are a promising solution for the recovery of P from acidic leachate. LbL membranes show a high level of versatility in terms of fine tuning for ion retention, which is necessary to achieve sufficient phosphorus yields. However, the stability of layer-by-layer modified membranes during phosphoric acid (H3PO4) filtration needs to be further investigated. In our study, we show that a polyethersulfone hollow fiber membrane modified with four or eight bi-layers was stable during immersing and filtering of a 15% H3PO4 solution. A sulfonated polyethersulfone (sPES)-based hollow fiber LbL membrane was only stable during filtration. Thus, we show the importance of applying real process conditions to evaluate membranes. Another important a...

Journal of Hazardous Materials, 2020

Polymers, 2019

Double emulsions are useful geometries as templates for core-shell particles, hollow sphere capsu... more Double emulsions are useful geometries as templates for core-shell particles, hollow sphere capsules, and for the production of biomedical delivery vehicles. In microfluidics, two approaches are currently being pursued for the preparation of microfluidic double emulsion devices. The first approach utilizes soft lithography, where many identical double-flow-focusing channel geometries are produced in a hydrophobic silicone matrix. This technique requires selective surface modification of the respective channel sections to facilitate alternating wetting conditions of the channel walls to obtain monodisperse double emulsion droplets. The second technique relies on tapered glass capillaries, which are coaxially aligned, so that double emulsions are produced after flow focusing of two co-flowing streams. This technique does not require surface modification of the capillaries, as only the continuous phase is in contact with the emulsifying orifice; however, these devices cannot be fabrica...

The Journal of Physical Chemistry B, 2017

ACS applied materials & interfaces, Jan 27, 2016

A new nanofiltration (NF) hollow fiber membrane is developed by using two oppositely charged poly... more A new nanofiltration (NF) hollow fiber membrane is developed by using two oppositely charged polyelectrolytes coagulating into a polyelectrolyte complex (PEC) onto polyether sulfone base polymer. The particular membrane architecture emerges during a single-step procedure, allowing setting both the porous negatively charged support of the hollow fiber and the separation layer containing also the positive polyelectrolyte (PEI/PDADMAC) through a single layer dry-jet wet spinning process. The novelty is two-pronged: the composition of the hollow fiber membrane itself and its fabrication procedure (one-step fabrication of membranes employing polyelectrolytes). These result in highly permeable hollow fiber membranes with a stable separation layer and performance at par with the membranes reported in literature obtained by multistep processes. More importantly, the membranes are obtained through a simple, very fast (one-step), and less expensive procedure. The best performance among these ...

Scientific reports, Jan 3, 2016

Recent research has established that electroconvection can enhance ion transport at polarized sur... more Recent research has established that electroconvection can enhance ion transport at polarized surfaces such as membranes and electrodes where it would otherwise be limited by diffusion. The onset of such overlimiting transport can be influenced by the surface topology of the ion selective membranes as well as inhomogeneities in their electrochemical properties. However, there is little knowledge regarding the mechanisms through which these surface variations promote transport. We use high-resolution direct numerical simulations to develop a comprehensive analysis of electroconvective flows generated by geometric patterns of impermeable stripes and investigate their potential to regularize electrokinetic instabilities. Counterintuitively, we find that reducing the permeable area of an ion exchange membrane, with appropriate patterning, increases the overall ion transport rate by up to 80%. In addition, we present analysis of nonpatterned membranes, and find a novel regime of electroc...

Chemistry of Materials, 2014

Physical chemistry chemical physics : PCCP, Jan 7, 2015

Nowadays NH3 is exclusively synthesized by the Haber process. Unfortunately, the energy demand an... more Nowadays NH3 is exclusively synthesized by the Haber process. Unfortunately, the energy demand and the CO2 emissions due to H2 production are high. Hydrogen production utilizes precious carbon sources such as coal and natural gas. In the past we proposed an alternative process concept using a membrane electrode assembly in an electrochemical membrane reactor (ecMR). At the anode H2O is oxidized at an IrMMO catalyst to form protons. By applying an external potential to the ecMR N2 is reduced to NH3 at the cathode. Just recently Rh and Ru were identified as possible cathodic electrocatalysts by DFT calculations. We present an easy and highly efficient method for galvanic coatings of Rh and Ru on randomly structured Ti felts to be used in a membrane electrode assembly. Linear sweep voltammetry measurements give a slightly higher activity of Ru for the liquid phase electrochemical NH3 synthesis. The NH4(+) concentration reached is 8 times higher for Ru than for Rh. From an economical po...

Phys. Chem. Chem. Phys., 2014

A new NH3 synthesis process using an electrochemical membrane reactor including N2 production and... more A new NH3 synthesis process using an electrochemical membrane reactor including N2 production and product separation is modelled in Aspen+.