Sustainable Organic Solvent Nanofiltration Membranes

Abstract

Organic solvent nanofiltration (OSN) is a pressure-driven separation method that has the potential to improve the energy efficiency of the pharmaceutical, fine chemical and petrochemical industries. However, issues concerning the sustainability of OSN membrane fabrication, and the difficulty in comparability and reproducibility of membrane performance ultimately hinder the industrial implementation of OSN as a truly sustainable technology. First, 177 articles published from 2015 to 2019 were critically assessed to determine how the scientific value and industrial impact of OSN studies can be improved. Recent trends to increase the sustainability of OSN were also investigated highlighting fields where more development is required. Based on these findings, a series of best-practice recommendation on data reporting was assembled to improve the comparability of membrane sustainability and performance. Second, a variety of green strategies focusing on renewable materials were employed in membrane fabrication. Nonwoven composite membrane backing materials (also known as supports) were prepared using bamboo fibre, poly(lactic acid) (PLA), and dimethyl carbonate. The bio-based membrane supports exhibited a porous structure and comparable mechanical strength to commercial petroleum-based backing materials. The applicability of bamboo/PLA composites as membrane supports was verified by casting an OSN membrane on top and demonstrating stable filtration performance over two weeks. The utilisation of six kind of biophenol coatings on six type of polymeric loose membranes was also investigated. A systematic study was reported and the influence of coatings on the polymer membrane properties was examined. The application of biophenol coatings resulted in lower permeance (by 22-92%) and decreased molecular weight cut-off (by 12-79%). Dopamine coatings also improved the solvent resistance for some of the membranes. Finally, prawn-shell-derived chitin, chitosan and xanthan gum were used to fabricate membranes with the aim to lay down the foundation of these chitin-based materials for several applications including OSN, packaging or wound treatment. Preliminary investigation showed that all fabricated membranes demonstrated chemical stability in organic solvents including harsh polar aprotics making them applicable for organic solvent filtration applications. The presented approaches can open new horizons for fabricating green membranes from renewable materials that are not limited to OSN but could include microfiltration, air filtration, biomedical and packaging applications.

Date of Award	1 Aug 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Krishna Persaud (Supervisor) & Christopher Blanford (Supervisor)