Hydrophobicity and membrane distillation performance of glass fiber membranes modified by dip coating of pure PDMS

With growing concern for environmental issues associated with the use of chemicals and nanomaterials to achieve membrane hydrophobicity, polydimethylsiloxane has emerged as a promising and eco-friendly alternative. However, few studies have explored the application of pure PDMS solutions through dip coating to achieve hydrophobicity in membranes designed for membrane distillation; a process which demands the membranes possess specific porosity and pore size characteristics. This study explored how dip coating with different PDMS concentrations affected the hydrophobicity and physical properties of glass fiber membranes. Increasing the concentration of polydimethylsiloxane up to 15% resulted in a stepwise rise in hydrophobicity, but the functionality as a membrane was compromised when the concentration reached 20%. Hydrophobicity on the membrane surface was higher with 15% PDMS treatment than on the chemically grafted membrane, but the latter demonstrated superior performance in the membrane distillation process. Nevertheless, the study confirms the potential of the pure PDMS-coated membrane as a viable option for membrane distillation, with the possibility of enhancing performance through improvements in pore size and surface morphology.