Membrane Distillation and Hydrogen Generation Hybrid Systems

Abstract

The rise in human activity in recent years has resulted in increased energy demand and more waste generation. To fulfill the world's high energy demands, a green, sustainable fuel must be utilized to decrease carbon dioxide emissions and mitigate the outcomes of climate change. Electrolysis, a process of splitting water into hydrogen and oxygen, has excellent potential to produce clean fuel at a large scale. However, electrolysis requires high-purity water or freshwater, which is limited and scarce in many regions. On the other hand, the presence of heavy metals (HMs) in wastewater contributes significantly to global water pollution. Zinc (Zn), lead (Pb), iron (Fe), chromium (Cr), nickel (Ni), and cadmium (Cd) are among the common heavy metals found in wastewater, and all are harmful even with small concentrations. Herein, we propose an integrated hybrid system that utilizes membrane distillation (MD) to treat wastewater and generate permeate as an electrolyte in electrolysis for hydrogen generation. This study also aims to analyze the impact of HM ions on the hydrogen evolution reaction (HER) during electrolysis. Our observations from electrochemical analysis with linear sweep voltammetry (LSV), cyclic voltammetry (CV), and impedance reveal that low HM concentration in permeate wastewater has a negligible effect on HER, showing a better performance than the untreated wastewater. We also demonstrate a decay in the HER performance in the permeate comparable to (Deionized) DI water through a detailed stability analysis. The Faradaic efficiency of hydrogen evolution of the DI water, untreated wastewater, and MD treated wastewater showed the superiority of the latter in comparison to the untreated wastewater. The main results of this study approve the applicability of MD treated wastewater as an electrolyte to generate hydrogen. Repurposing wastewater for green hydrogen generation addresses the major concerns of the global water-energy nexus.

Date of Award	18 Dec 2023
Original language	American English
Supervisor	Al Marzooqi (Supervisor)