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Item type:Publication, Access status: without files , Fundamental insights into the rejection behavior of polyimide-based OSN membranes(2021-06-15); ; Organic solvent nanofiltration (OSN) is still a niche technology in the chemical industry due to time and money consuming process development, as organic solvents cause complex interactions between membrane, solvent, and solute. These interactions are not fully identified, and a fundamental understanding of mass transfer through OSN membranes is not established so far. Accordingly, mathematical models in OSN lack a general predictive capability. To overcome this problem, we aim to extend the current knowledge by a comprehensive experimental investigation of two polyimide membranes in combination with 17 solutes with molecular weights of 114–339 g/mol covering the range from nonpolar to polar, and five solvents with various properties. The results indicate solvent-dependent rejection phenomena that may be explained by a difference in the impact of solute properties on the rejection in dependency of the solvent. Based on these findings, three solvent-dependent solute sensitivity regions are derived similarly to previous results for PDMS membranes. The investigation of membrane–solvent interactions revealed an impact of the spatial distance in the 3D space of the total Hansen solubility parameter between solvent and membrane with a specific impact on membrane–solute sensitivity. These new findings contribute to a better understanding of transport phenomena and can serve as a new basis for predicting the separation performance in OSN.Publicationtype: Journal Article60 - 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 Article40