Fabrication of Fouling Resistance Membrane Assisted with Green Nanofillers for Harvesting Energy from Oil and Gas Produced Water using Reverse Electrodialysis

Abstract

Produced water, the biggest wastewater stream on the basis of volume during oil and gas operations, is a complex combination of organic and inorganic components. Moreover, the freshwater shortage, especially in arid regions, makes the management and treatment of produced water more beneficial. The large volumes of high-salinity produced water from the oil and gas industry can be combined with a low-salinity stream to harvest salinity gradient power in Reverse Electrodialysis (RED). However, the dissolved organic and heavy metals present in produced water can interact and change the transport capabilities of the ion-exchange membranes affecting performance of RED. Composite membranes have been used for removing different contaminants from wastewater due to their high selectivity and enhanced properties. In this work, Graphene Quantum Dots (GQDs) synthesized from waste carton paper were used as green nanofillers to fabricate composite membranes. The synthesized GQDs were characterized using XRD, RAMAN, TGA, FTIR, SEM and TEM. The polymer used, Polyethylene Terephthalate (PET), is recycled from waste plastic bottles. GQDs-PET membranes were fabricated using the phase inversion method. The optimal composite membrane, 0.5 wt.% GQDs-PET membrane, showed higher pure water flux (24 L/m2.hr.bar) compared to pristine PET membrane (9.9 L/m2.hr.bar). The SEM analysis and porosity measurements of the membranes confirmed the changes in the structure of the membranes with the addition of GQDs, resulting in higher water flux. The PET-GQDs membrane demonstrated remarkable removal for Phenol (>94%) under alkaline feed conditions (pH∼9.5) compared to the pristine PET membrane for more than 240 min in a continuous operating crossflow ultrafiltration system. Based on the pH and zeta potential studies, this performance of the GQDs-PET membrane can be attributed to the negative surface charge of the membrane created with the incorporation of GQDs, which lead to electrostatic repulsions between membrane and phenoxide ion to provide a stable removal of phenol at high pH.

Date of Award	8 May 2024
Original language	American English
Supervisor	Emad Alhseinat (Supervisor)