Nanoparticle-Enhanced PVDF Flat-Sheet Membranes for Seawater Desalination in Direct Contact Membrane Distillation

In this study, hydrophobic functionalized carbon nanotubes (fCNTs) and silica nanoparticles (fSiO(2)NPs) were incorporated into polyvinylidene fluoride (PVDF) flat-sheet membranes to improve their performance in membrane distillation (MD). The performance of the as-synthesized membranes was evaluated against commercial reference polytetrafluoroethylene (PTFE) flat-sheet membranes. The water contact angle (WCA) and liquid entry pressure (LEP) of the PVDF membrane were compromised after incorporation of hydrophilic pore forming polyvinylpyrrolidone (PVP). These parameters were key in ensuring high salt rejections in MD processes. Upon incorporation of fCNTS and fSiO(2)NPs, WCA and LEP improved to 103.61 degrees and 590 kPa, respectively. Moreover, the NP additives enhanced membrane surface roughness. Thus, an increase in membrane roughness improved WCA and resistance to membrane wetting. High salt rejection (>99%) and stable fluxes (39.77 kg m(-2) h(-1)) were recorded throughout a 3 h process evaluation where 3.5 wt% NaCl solution was used as feed. These findings were recorded at feed temperature of 60 celcius. Evidently, this study substantiated the necessity of high feed temperatures towards high rates of water recovery.

Automated summary

Hydrophobic functionalized carbon nanotubes (fCNTs) and silica nanoparticles (fSiO(2)NPs) were added to polyvinylidene fluoride (PVDF) flat-sheet membranes to improve their performance in membrane distillation (MD). The incorporation of fCNTS and fSiO(2)NPs improved the water contact angle (WCA) and liquid entry pressure (LEP) of the PVDF membrane, as well as the membrane surface roughness. This resulted in high salt rejection and stable fluxes in the MD process.