Anti-wetting behaviour of a superhydrophobic octadecyltrimethoxysilane blended PVDF/recycled carbon black composite membrane for enhanced desalination

Abstract

A novel superhydrophobic octadecyltrimethoxysilane (OTMS)-modified composite membrane was fabricated by incorporating recycled carbon black (CB) into a polyvinylidene fluoride (PVDF) membrane. Waste tires have been treated with extraction and high-temperature calcination to obtain recycled CB. After incorporating CB into the PVDF solution, a steep increase of 18–20% was observed in the loss and storage moduli. CB was observed to be an ideal filler for doping the PVDF solution to enhance the mechanical properties of the material. OTMSs are known for their low surface energy, which improves hydrophobicity. Moreover, OTMSs were found to be ideal agents for enhancing the superhydrophobicity of PVDF membranes. The results of surface treatment with OTMS, CB loading, particle size, and membrane properties and their effect on desalination performance were thoroughly studied. The composite membrane was observed to be superhydrophobic with a contact angle of 160° and exhibited high desalination performance in terms of permeate water flux and salt rejection. The fabricated membrane has been reused after physical cleaning in order to analyse the anti-wetting and long-term performance.