Novel electrically conductive PVDF-carbon composite membranes for wastewater purification and electrochemical defouling

Abstract

Membrane separation technology has emerged as a promising and widely applied solution in various industrial sectors. However, the persistent issue of membrane fouling limits the efficiency and longevity of membrane-based processes. This PhD thesis introduces an innovative, cost-effective and sustainable approach to address this challenge by introducing an electrical field in the membrane cleaning process. of the optimised conductive ultrafiltration PVDF-CNT-0.5 membrane at +3V electrical field, the flux recovery rate (FRR) is 89.1 %, suggesting that the superior performance is dominated by electrochemistry reaction. In addition, the collected current signal ratio in the defouling process has a similar trend with the measured flux recovery rate, providing a novel method to explore the science behind the membrane fouling process. Moreover, research into PVDF-GP membranes uncovers pathways for tailoring conductivity enhancement to optimise performance. By forming a top layer on the composite membrane, a graphite-incorporated PVDF composite membrane obtained a 15- time electrical conductivity improvement compared with the PVDF membrane. Comparing the difference between graphite-incorporated and CNT-incorporated membranes reveals and discusses the science behind crucial operation parameter membrane fabrication and key operation parameters. Meanwhile, another electrostatic-controlled mechanism was proposed for defouling with the PVDF-GP membrane. In addition, the study delves into the hybrid carbon and Fe2O3-deposited membranes, offering a comprehensive evaluation of the contributions of both conductivity and electrocatalytic properties in the Electrical Assisted Membrane Cleaning (EAMC) process, revealing the potential conflict relationship between the electrostatic mechanism and the electrochemistry reaction mechanism. Depositing the functional material provided a promising pathway to deal with this conflict. The Fe2O3-deposited GP/CNT-0.5/0.5 achieved superior FRR and 88.6 % with +3V defouling; after reducing the applied potential to +1.3 V, the Fe-deposited membrane still achieved 78.8% FRR, which further improved the energy efficiency in the defouling process.

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Identifiers

ORCID for Zheng Jiang: orcid.org/0000-0002-7972-6175

ORCID for Carlos Ponce De Leon Albarran: orcid.org/0000-0002-1907-5913

ORCID for John Atkinson: orcid.org/0000-0003-3411-8034

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