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

Abstract

In this study, hydrophobic functionalized carbon nanotubes (fCNTs) and silica nanoparticles (fSiO2NPs) 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 fSiO2NPs, WCA and LEP improved to 103.61° 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 ℃. Evidently, this study substantiated the necessity of high feed temperatures towards high rates of water recovery.

Effective Membrane Distillation of Landfill Leachate Concentrate Using a Superhydrophobic SiO2/PVDF Membrane for Resource Recovery

“…29−32 Therefore, enhancing the hydrophobicity of the porous membranes is essential for practical applications of membrane distillation technology. 33,34 Currently, the widely used hydrophobic membranes include PVDF-, 35−37 PTFE-, 38−41 PE-, 42 and PP-based polymeric membranes. 43,44 However, these polymeric membranes usually suffer from poor chemical and thermal stability as well as membrane wetting and fouling.…”

“…Yan et al used hydrophobic PVDF membranes for the purification of landfill leachate using a membrane distillation process, indicating that membrane distillation enabled to completely retain the contaminants in the landfill leachate (the corresponding rejection of 98.93, 99.19, and 99.95% for total organic carbon, total phosphorus, and metal ions, respectively) . Even though these research findings demonstrate the superiority of membrane distillation technology in handling various highly loaded wastewater, membrane wetting still remains an unavoidable challenge impairing membrane performance. − Therefore, enhancing the hydrophobicity of the porous membranes is essential for practical applications of membrane distillation technology. , …”