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Engineering Nanocomposite Membranes; Fabrication, Modification and Application / Saif Al-Aani

Swansea University Author: Saif Al-Aani

DOI (Published version): 10.23889/SUthesis.40523

Abstract

The engineering of novel membranes through fabrication and modification using engineered nanoscale materials (ENMs) presents tremendous opportunity within desalination and water treatment. This work presents an endeavour dedicated to investigate the design and fabrication of polymeric membranes and...

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Published: 2018
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa40523
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Abstract: The engineering of novel membranes through fabrication and modification using engineered nanoscale materials (ENMs) presents tremendous opportunity within desalination and water treatment. This work presents an endeavour dedicated to investigate the design and fabrication of polymeric membranes and nanoscale materials. Also, to probe the role of nanoscale materials integration on the function of separating membranes aiming to diminish the propensity of the surface to foul.In the first part of the work, an attempt was made to research and compare the potential of versatile UF membranes structures in terms of morphology, surface characteristics and performance. The potential performance of the hand-made fabricated (UF) membranes was systematically evaluated against three organic model foulants with dissimilar origins; humic acid (HA), sodium alginate (NaAlg), and bovine serum albumin (BSA), under different initial feed concentration and pH chemistry. A diverse range of surface characteristics and morphologies have been produced as a result of varying the dope casting solution concentration, which corresponds to the wide range of commercially available UF membranes (6, 10, 35 and 100kDa). Also, a disparate fouling behaviour was observed depending on the membrane characteristics and the organic model foulant used. A one or more pore blocking mechanism were distinctly observed depending on the UF membrane cut-off used.Subsequently, the research presented the development of a novel nanocomposite membrane incorporating antimicrobial nanoparticles which have the potential to lower membrane biofouling. Antibacterial hybrid nanostructures (HNS) comprising of Ag decorated MWCNTs were successfully synthesised with the assistance of microwave irradiation. The HNS were then employed to fabricated antibacterial nanocomposite membranes via the classical phase inversion technique in order to assess their antimicrobial properties against two bacterial species; E. coli and S. aureus. The nanocomposite membranes remarkably displayed antibacterial activity (4.24 and 2.9 log kill) against the two species respectively. A higher stability under crossflow conditions was also demonstrated.Finally, for desalination applications, novel HNS comprising of a mussel-inspired PDA coated M/MO–MWCNTs, were successfully synthesised and used to fabricate TFN membranes. For comparison, four different M/MO (Al2O3, Fe2O3, TiO2 and Ag) nanoparticles (NPs) were in situ synthesised/loaded on the surface of CNTs, and the resultant HNS were further coated with a thin polymeric film of PDA. An intermediate layer of the HNS was then deposited on a PES substrate membrane, and an interfacial polymerisation (IP) process was carried out to render a polyamide (PA) thin layer above the intermediate layer. Both HNS and TFN were characterised using different characterisation tools, and the performance of nanofiltration (NF) membranes was evaluated against monovalent, divalent salts and heavy metal solutions. The fabricated TFN-NF membranes had higher performance in terms of their permeation characteristics compared to the thin film composite TFC membrane (⁓9.6-11.6 LMH), while maintaining their selectivity (≥91%) against both monovalent and divalent salts solutions, and (> 92%) against the multi-component heavy metal solution. The experimental results disclosed a high retention capability for TFC and TFN membranes along with greater potential stability/compatibility within the polymeric PA matrix. This implies that the NF membranes fabricated in this work can be employed for water reclamation purposes.
Keywords: Novel membranes, water treatment
College: Faculty of Science and Engineering

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