Composite Electrospun Membranes for Water Desalination using Direct Contact Membrane Distillation

Abstract

The most basic component of life is water. However, the world's naturally occurring fresh water supplies are seriously threatened by a rise of economic development, industrialization, and uncontrolled population increase, particularly in the Middle East and North Africa (MENA) region. Desalination is seen to be a viable way to meet the steadily rising demand for fresh water due to the restricted availability of fresh water. To make saltwater usable, the extra salts and minerals are removed using a process called desalination. Membrane-based technologies have been more popular in the last few decades because of their high separation efficiency, affordability, and simplicity of use. In this study, we investigate the enhancement of electrospun polyvinylidene fluoride-co- hexafluoropropylene (PVDF-HFP) membranes for application in Direct Contact Membrane Distillation (DCMD). Through a series of meticulous experiments and analyses, we demonstrate the significant impact of modifying these membranes with polydimethylsiloxane (PDMS) elastomer on their physical, mechanical, and thermal properties. Electrospinning was employed to fabricate PVDF-HFP membranes, which were then subjected to various modification steps, including heat pressing and dipping in PDMS solutions of different concentrations and durations. Characterization studies revealed that the addition of PDMS elastomer led to a reduction in pore diameters, strengthened surface fibers, and improved thermal and mechanical stability. This resulted in membranes better suited to withstand the harsh conditions encountered in DCMD processes. Furthermore, our findings demonstrate that while dipping PVDF-HFP membranes in PDMS solutions had adverse effects on certain membrane properties, such as thickness and pore diameter, the overall performance of these membranes in DCMD was significantly enhanced. The modified PVDF-HFP membranes exhibited improved flux and salt rejection rates during DCMD operations, indicating their suitability for various water purification applications, particularly in saltwater desalination. Overall, this study provides valuable insights into the modification of electrospun membranes for DCMD applications, offering a promising avenue for the development of efficient and durable membrane-based water purification systems.