Characterisation of Organic Solvent Nanofiltration membranes in multi-component mixtures: Process design workflow for utilising targeted solvent modifications

Organic Solvent Nanofiltration (OSN) is a pressure-driven membrane separation process for separating liquid organic solvents. It can potentially be applied in chemical, petrochemical and pharmaceutical industries. In contrast to well-established design approaches for conventional unit operations such as distillation, design methods for integrating OSN in chemical production processes are very limited. The reason is a lack of information on expected OSN membrane performance as well as missing general understanding of the complicated transport mechanism through OSN membranes. Therefore, this paper introduces a workflow that accounts for the current limited information and makes a general process design feasible. This includes a solvent/membrane selection in early stages of process design beyond state-of-the art OSN membrane screening experiments that so far do not address solvent variations. As the interaction between solute, solvent and membrane material on the separation behaviour of the membrane is substantial, an integrated selection of membrane and solvent for a targeted rejection of a solute might lead to large improvements. Within the developed four-step design workflow, also the integration of design tools such as membrane rejection maps (MRM), membrane modelling maps (MMM) and OSN membrane cascade based optimisation are addressed. Targeted solvent modifications/additions may therefore result in better flux and/or rejection properties of Puramem™280 and GMT-oNF-2 and hence, in reduction of production costs. The design approach is demonstrated on a case study of industrial importance which is the recycling of homogeneous catalysts.