Innovations in water desalination: enhancing air gap membrane distillation performance by the incorporation of clay nanoparticles into PVDF matrix membranes†

Abstract

This study showcases the remarkable permeate flux rates achieved in water desalination using phase-inversion polyvinylidene difluoride (PVDF) membranes by the incorporation of clay nanoparticles within the polymer matrix, leading to a performance that surpasses that of commercial membranes. These findings hold promising implications for addressing water scarcity issues in various regions around the globe. The study focuses on membrane improvement by incorporating both montmorillonite (MT) and Cloisite 20A (organomontmorillonite, OMT). The permeate flux of the most effective OMT-enhanced membrane (with a 4 wt% loading) surpassed that of the commercial PVDF membrane by 12% and outperformed the pure PVDF membrane by 30% after a 24 hour testing period in air gap membrane distillation (AGMD), with rejection values exceeding 99.8%. Moreover, this membrane exhibited stability over 5 days of continuous testing, proving better performance than commercial PVDF membranes when exposed to a concentrated fouling humic acid solution. This fouling test experienced a 40% reduction in permeate flux compared to the 60% decline observed in the commercial PVDF membrane. These enhancements are attributed to increased surface porosity, higher liquid entry pressure, smaller mean pore size, and a uniform distribution of clay particles within the membrane matrix.