High performance in-situ tuned self-doped polyaniline (PANI) membranes for organic solvent (nano)filtration.

Hassan Alali Alhweij, Emma Anna Carolina Emanuelsson, Salman Shahid, Jannis Wenk

Research output: Contribution to journalArticlepeer-review

6 Citations (SciVal)

Abstract

Cross-linked polyaniline (PANI) membranes are attractive for organic solvent nanofiltration (OSN). However, inadequate tuneability to cover the full nanofiltration (NF) separation range, prolonged post-treatment cross-linking using hazardous organic chemicals and poor permeance limit their widespread application. This work introduces a new strategy to tune the transport properties of PANI membranes to suit the rejection spectrum of NF membranes without compromising permeance. Incorporating different molecular weight organic acids, metanilic acid (MA) and poly (2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA), facilitated cross-linking during polymer precipitation at different aqueous coagulation bath acidic strength using non-solvent induced phase separation (NIPS). Static ageing tests for PANI membranes immersed in tetrahydrofuran (THF) for 30 days showed no physical or chemical deterioration. All membranes were stable during long-term dynamic crossflow filtration tests over 250 h with sequential feed of methanol, acetonitrile and THF. THF permeance was 2.1–16.4 L m−2 h−1 bar−1 with apparent molecular weight cut off (MWCO) between 250 and 1000 g mol−1. PAMPSA doped membranes were successfully cross-linked but required wet annealing post-treatment to obtain membranes in NF range. The MA doped membranes surpassed the performance of cross-linked PANI membranes with glutaraldehyde (organic cross-linker) showing a 2.5 times higher permeance with better rejection. In comparison to commercial polyimide membranes, PANI membranes prepared in coagulation bath ≥0.5 M HCl(aq) were stable in N,N-dimethylformamide (DMF) whereas the former suffered complete damage. This work represents a simplified technique to in-situ optimise permselective properties of OSN self-doped PANI membranes for various applications in food, pharmaceutical and petrochemical industries.
Original languageEnglish
Article number124682
Number of pages14
JournalPolymer
Volume245
Early online date1 Mar 2022
DOIs
Publication statusPublished - 6 Apr 2022

Bibliographical note

Funding Information:
H.A. was supported by a University of Bath research scholarship. The authors thank the technicians' team at the Department of Chemical Engineering and the Bio-imaging lab at the University of Bath for support and advice.

Funding Information:
Organic solvent nanofiltration (OSN) is a pressure-driven technique which allows fractionation and purification for a diverse range of disperse mixtures in solvent streams [1,2]. Solutes with molecular weight (MW) between 200 and 2000 g mol?1 are retained whereas small solvent molecules permeate through the membrane [3,4]. OSN membranes allow effective and consistent removal of impurities, high solvent recovery rates including flexibility to process feedstocks of fluctuating compositions without thermally affecting the quality of solutes, as alternative thermal separation processes [ 5?7]. Polymeric materials are the main building blocks for OSN membranes due to the ease of processing, lower fabrication costs and higher flexibility compared to inorganic materials such as ceramics [8]. Currently, integrally skinned asymmetric (ISA) polymeric membranes prepared via non-solvent induced phase separation (NIPS) are mostly used for OSN providing straightforward scale-up and low manufacturing cost [9,10]. During NIPS, gradual separation of membrane material from dope solution takes place by phase inversion in a non-solvent coagulation bath (typically water) [11]. As a result, an ISA membrane is formed which possesses same chemical composition with a skin-layer on the top of a porous and either finger-like or sponge-like support layer [12].H.A. was supported by a University of Bath research scholarship. The authors thank the technicians' team at the Department of Chemical Engineering and the Bio-imaging lab at the University of Bath for support and advice.

Keywords

  • High-performance
  • Nanofiltration
  • Organic solvent
  • Polyaniline
  • Tuned

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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