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Item type:Publication, Access status: without files , Open and FAIR data for nanofiltration in organic media: a unified approach(Elsevier, 2025-01-01); ; ; ; Organic solvent nanofiltration (OSN), also called solvent-resistant nanofiltration (SRNF), has emerged as a promising technology for the removal of impurities, recovery of solutes, and the regeneration of solvents in various industries, such as the pharmaceutical and the (petro)chemical industries. Despite the widespread use of OSN/SRNF, the presence of scattered, non-standardized data, and the absence of openly accessible data pose critical challenges to the development of new membrane materials and processes, their comparison to the state-of-the-art materials, and their fundamental understanding. To overcome these hurdles, data from peer-reviewed research articles and commercial datasheets were curated via a standardized procedure to obtain an extensive dataset on the membrane materials, synthesis parameters, operational conditions, physicochemical properties, and performance of OSN/SRNF membranes. Thanks to a truly impressive joint effort of the OSN/SRNF community, the dataset contains, as per April 2024, 5006 unique membrane filtrations from 294 publications for 42 solvents under several process parameters. This findable, accessible, interoperable, reproducible, and open (FAIR/O) dataset is available on both the OSN Database and the newly inaugurated Open Membrane Database for SRNF (OMD4SRNF). These databases provide multiple visualization and data exploration tools. Here, the standardized procedure applied to curate the data and the functionality of the databases are outlined, as well as the online user interface to deposit new data by external users on the OMD4SRNF. This community-led project has been supported by all the co-authors of this work. Most importantly, they additionally agreed to systematically deposit their future peer-reviewed data on OSN/SRNF into the databases. We thereby pave the road for FAIR/O data in the field of OSN/SRNF to increase transparency, enable more accurate data analysis, and foster collaboration and innovation.Publicationtype: Journal Article31 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Electrically conducting duplex-coated gold-PES-UF membrane for capacitive organic fouling mitigation and rejection enhancement(2021-02-15); ; Recent studies showed that the application of an electrical potential onto an ultrafiltration membrane surface exhibit several advantages with respect to the fouling and rejection behaviour. Sputter deposition of ultra-thin metal layers onto commercial flat sheet membranes proved to be a simple way of producing conductive metal-polymer-composite membranes. Adopting the novel approach of duplex-coating the active and support layer of a flat sheet membrane eliminates the need for an additional counter electrode and significantly simplifies module design for conductive flat sheet systems. Cross-flow filtration experiments were conducted with organic model foulants such as sodium alginate, bovine serum albumin (BSA), humic acids as well as with natural organic matter (NOM) from Hohloh lake water. The duplex-coating induced an additional electric field through the membrane itself, resulting in enhanced performance not only for cathodic but also for anodic charging of the active membrane layer. Hohloh lake water fouling experiments showed decreased permeability of 47% for the uncharged membrane to 16% and 38% for the cathodic and anodic charging, respectively. Moreover, a significant increase in NOM-rejection was observed with 27% for the uncharged membrane and 72% and 49% for the cathodic and anodic potentials, respectively. Finally, the effectiveness of externally charged duplex-coated membranes was demonstrated by comparing rejection and fouling rates with conventional membrane-electrode vs. counter electrode configuration, showing an almost similar enhancement in performance.Publicationtype: Journal Article107 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Can the variance in membrane performance influence the design of organic solvent nanofiltration processes?(2019-04-01); ; ; ; The development of organic solvent nanofiltration (OSN) membranes has been a continuous effort during the past decade. Several groups generated and published experimental results and simulations with either tailor-made membranes or industrial products. The published data space is diverse, with a single publication often focusing on a certain membrane only, a group of specific solutes only, on the effect of solvent only. A comprehensive comparison of all of these is still lacking. An analysis on the reliability of quantified transport parameters is missing, in particular when different analysis methods and different membrane systems are used. The technology is in its incubation phase with a need for reliable data and measurement standards to ground the process design on reliable membrane transport properties. This study uses an unprecedented extensive standard experimental procedure to measure separation characteristics of polymer membranes for the separation of organic solutes from organic solvents. For a variety of different solvents, solutes and membranes, flux and retention measurements are rigorously characterized by round robin tests at different labs using different analytical systems. This extensive collaborative study evaluates for the first time which fluctuations in results occur under comparable conditions of lab-scale experiments at different locations and which influence these have on the design of OSN processes. Utilizing the variance in the membrane transport data, a process design study and optimization is presented. For the first time ever, we report how variance in membrane transport properties can influence the process design ranging from a simple single stage system for values for the upper transport limits, to a two stage system with a permeate recirculation for mean values, to a complex three stage system for the lower limits.Publicationtype: Journal Article26 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Solvent dependent membrane-solute sensitivity of OSN membranesOrganic solvent nanofiltration (OSN) offers great potential as a versatile tool for process intensification in the chemical industry. Nevertheless, the mass transfer mechanism through OSN membranes is not fully understood. The complex interactions between membrane, solvent and solute make it difficult to predict the separation performance of the membrane. In order to increase the fundamental understanding of the underlying transport phenomena systematic experimental investigations were carried out. A matrix of solvents, solutes and membranes was defined, covering a wide range of properties. The selection of the solutes was based on their industrial relevance to cover representative solute properties. Another criterion was their molecular weights, which should be rather low in order to obtain rejection less than 100%, to evaluate potential solute specific impact factors. The separation characteristics of 17 polar to apolar solutes with molecular weights from 114 g/mol to 339 g/mol were investigated. Moreover, five solvents and two membranes were included in the systematic investigation. On the basis of the results different solvent dependent solute sensitivity regions were identified for each membrane which differ by the impact of solute properties on the rejection. Different transport mechanisms seem to dominate within the different solute sensitivity regions. A correlation of the hydrogen bonding capacity of the solvents with the impact of solute properties on the rejection was found. This new insight offers new perspectives for the prediction of membrane rejection behavior in OSN.Publicationtype: Journal Article39 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Flux-enhanced PVDF mixed matrix membranes incorporating APTS-functionalized graphene oxide for membrane distillationAir gap membrane distillation (AGMD) is an emerging desalination technology with the potential to meet the challenge of global water scarcity due to its low cost and high thermal efficiency compared to other processes. However, despite the potential of AGMD, a lack of appropriate membranes limits its commercial application. Therefore, this study was focussed on the fabrication of high flux, robust membranes for the purification of artificial sea water by incorporating graphene oxide functionalized with 3-(aminopropyl)triethoxysilane (APTS) into PVDF polymer solutions. Successful functionalisation of GO with APTS was confirmed with XPS and FTIR. It was shown that the addition of GO and GO-APTS enhanced the permeate flux by 52% and 86%, respectively, compared to pure PVDF. The best performing membrane contained 0.3 wt% GO-APTS (with respect to PVDF) and had a flux of 6.2 LMH (L m h ) whilst maintaining perfect salt rejection (>99.9%). These improvements were attributed to increased surface and bulk porosity, larger mean pore size and hydrophilic interactions owing to the functional groups of GO and GO-APTS. These membranes are evidence of the potential that GO and related materials have as nanocomposite fillers in high performance desalination membranes. −2 −1Publicationtype: Journal Article43 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Solvent recovery and deacidification by organic solvent nanofiltration: Experimental investigation and mass transfer modelingNon-edible oils, waste oils and animal fats are promising feedstocks for more economic and ecological production processes. However, the composition of these low-quality oils, especially the content of free fatty acids, strongly fluctuates requiring the development of flexible process concepts. Therefore, this study investigates the potential of organic solvent nanofiltration for important applications in the oleochemical industry. It is shown that an efficient recovery of non-polar extraction solvents is possible for a wide range of low-quality oils. Commercially available PDMS-based membranes enable high solvent fluxes and rejection of triglyceride and fatty acids. In deacidification experiments, high selective separation of free fatty acids from triglycerides for long-chain as well as medium-chain oils is achieved by using polar solvents and available polyimide-based membranes. The amount of solvent, which is added to the low-quality oils, is identified as crucial parameter for separation efficiency. Membrane performance is accurately described by a (reduced) solution-diffusion model with imperfections, for which mass transfer of solvents and fatty acids is described by the convective contribution, while mass transfer of triglycerides is described by the diffusive contribution.Publicationtype: Journal Article30 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Comparative analysis of full-scale membrane distillation contactors - methods and modules(Elsevier, 2016-12-01); ; ; ; A new multi-channel spiral-wound membrane distillation (MD) module with a membrane surface area of 27.5m2 was developed, constructed and characterized. For comparison, a set of different conventional single-channel direct contact membrane distillation (DCMD) module prototypes is introduced and experimentally evaluated, as well. Furthermore, a comprehensive assessment on DCMD module design and operation as well as methods for comparative thermodynamic MD module evaluation has been conducted. The methodical core of this work specifically addresses an integrative method for the derivation of the thermal energy demand of DCMD systems, comprising specifications of the external heat recovery system. A new strategy for the optimization of energy demand in DCMD is identified, which aims on the formation of parallel temperature profiles by adjusting the flow streams on the evaporator and the condenser channel. Suitable methods for a comparative analysis of different MD performance results are suggested and fundamental MD specifications are derived and applied to evaluate a set of different DCMD prototypes. The methods involve the analysis of the permeate output rate, flux and thermal energy consumption with respect to feed flow rate conditions. The optimization of flux and thermal energy consumption is identified to rely on conflicting requirements, which cannot be satisfied at the same time. The optimal combination of flux and thermal energy consumption depends on the projected scenario and may not be identified by a technical assessment alone. Economic considerations must be included. As final outcome, a method of specifying MD results by a representation of flux versus thermal energy consumption is suggested in order to allow a meaningful evaluation and to achieve global comparability among different MD configurations and other thermal separation technologies.Publicationtype: Journal Article75 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Effect of inorganic colloidal water constituents on combined low-pressure membrane fouling with natural organic matter (NOM)(2016-06); ; ; The impact of inorganic colloidal water constituents on fouling in low-pressure membrane systems was evaluated by carrying out ultrafiltration (UF) experiments using synthetic waters containing model foulants. Humic acid (HA), sodium alginate (SA), and bovine serum albumin (BSA) were chosen as model natural organic matter (NOM) foulants, and silicon dioxide and α-aluminum oxide were chosen as model inorganic colloidal foulants. The synthetic solutions were filtered using one lab-scale flat sheet UF system (i.e., unstirred filtration cell) and one pilot-scale hollow fiber UF system (i.e., custom made hollow fiber modules), both of which employed polyethersulfone (PES) membranes. Filtering the inorganic colloids by themselves did not result in any significant fouling, as evidenced by the negligible permeability decline and high hydraulic reversibility. However, when combined with NOM, severe permeability decline and hydraulic reversibility reduction were observed. Moreover, the permeability decline and reversibility loss of the combined inorganic colloids and NOM were more severe than the sum of the individual effects from organics and inorganic colloids, suggesting that combining the two acts to enhance fouling (i.e., synergistic fouling effects). Aluminum oxide tended to result in more severe synergistic fouling compared to silicon dioxide, suggesting that the inorganic colloid material character, especially its surface charge, affects the severity of combined fouling. Rejection of TOC and analysis of the fouled membranes by scanning electron microscopy indicated higher NOM adsorption by aluminum oxide colloids, which lead to a larger amount of foulants in the cake layer and a worse reversibility. Both the lab- and pilot-scale systems exhibited similar fouling behavior, thus indicating that the lab-scale system provides a meaningful representation of the pilot-scale system, even though the operating conditions are quite different. This study highlights the importance of interactions between foulants with respect to fouling in low-pressure membrane systems and showed conclusively that inorganic colloids play an important role in fouling of NOM. Moreover, present results underline the impact of colloidal surface charge on the resulting hydraulic and chemical fouling reversibility during ultrafiltration of natural waters containing NOM and inorganic colloids.Publicationtype: Journal Article179 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Kinetic modeling and selectivity of anion exchange in Donnan dialysis(2015-04-01); The objective of this work was to compare selective sorption and transport behavior of a Selemion AMV membrane for different anions with a theoretically derived kinetic model describing the Donnan dialysis (DD) process. This analysis resulted in a suggested relation for the diffusivity of small ions through "nanochannels" of ion exchange membranes. Mass transfer through boundary layers and membrane diffusion were modeled on the basis of the Nernst-Planck equation by introducing constant diffusivity ratios between the exchanging counter ions. To indentify the kinetic and selectivity coefficients, DD batch experiments with sodium nitrate, sulfate or dihydrogen phosphate as feed electrolytes and sodium chloride as receiver electrolyte were conducted. The derived kinetic model simulated the measured concentration changes very precisely after fitting three concentration-independent parameters and the concentration-dependent permeability coefficient. The selectivity sequence was found to be nitrate>sulfate>dihydrogen phosphate>chloride, while this sequence is strongly connected to activity in solution and in the membrane. This influence was very significant for sulfate, which resulted in higher removal efficiency than expected. Regarding diffusivity the identified sequence was nitrate>sulfate>chloride>dihydrogen phosphate. These results led to a correlation that describes diffusivity of counter ions through nanochannels as a function of hydrated cross section area and valence.Publicationtype: Journal Article41 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Effect of particle size and concentration on the synergistic UF membrane fouling by particles and NOM fractionsThe fouling behavior of different NOM fractions in combination with two micro-particles (0.5-10. μm and ~45. μm) and one nano-particle (5-15. nm) on UF membrane was investigated. Three NOM models, Aldrich humic acid (HA), bovine serum albumin (BSA) and dextran (DEX) were employed as representatives of humic substances, proteins and polysaccharides in natural waters. For all the NOM models, a significant synergistic fouling effect was observed between the organic fraction and the two micro-particles, as evidenced by the proportional increase of fouling resistance with the increase of particle concentration from 10 to 50. mg/L. Whereas at higher particle concentration of 100. mg/L, the synergistic fouling resistance became balanced, or even decreased in comparison with that at 50. mg/L, indicating that there might be a critical concentration range for the micro-particles, in which the particles caused the most pronounced synergistic fouling effect with the NOM fractions. As for the nano-particle of 5-15. nm, much lower synergistic fouling resistance was observed as compared with that of the micro-particles for all the NOM models. This work highlighted the importance of particle size and particle concentration (i.e. mass ratio of particle/NOM) on the combined membrane fouling behavior for UF of natural waters. Besides, the interplay of different NOM fractions in the particle layer also played a crucial role in UF membrane fouling, as demonstrated by the much higher synergistic fouling resistance caused by the HA-BSA-DEX mixture in the presence of different particles, as compared with that by HA alone.Publicationtype: Journal Article66