Preparation and properties of PVDF composite hollow fiber membranes for desalination through direct contact membrane distillation

Abstract

a b s t r a c tThe polyvinylidene fluoride (PVDF) composite hydrophobic hollow fiber membranes were fabricated for membrane distillation through non-solvent induced phase inversion by dispersing hydrophobic modified calcium carbonate nano-particles in the PVDF casting solution and using the mixture of LiCl and polyethylene glycol (PEG) as non-solvent additive. The influence of nano-particles on the spun hollow fiber membrane characteristics was investigated. The addition of hydrophobic nano-particles could optimize the sandwich-like morphology, narrow the pore size distribution, improve the membrane porosity and increase the membrane surface roughness and contact angle to some extent. The nano-particles also enhanced the crystallinity degree and thermal stability of the hollow fiber. In addition, the composite membranes presented stronger mechanical properties compared to the fiber without particles. During the desalination process of 3.5 wt% sodium chloride solution, the maximum transmembrane permeate flux about 46.3 kg/m 2 h with a lower thermal loss was obtained from the composite fiber when the hot feed inlet temperature and the cold distillate inlet temperature were at 80.5 • C and 20.0 • C, respectively. Furthermore, the composite membrane exhibited satisfying performance stability compared with the pure PVDF membrane in the 30 days continuous desalination experiments, indicating that the as-spun composite fiber may be of great potential to be utilized in MD process for desalination.

Preparation and characterization of PVDF flat-sheet membranes for direct contact membrane distillation

“…PTFE membrane is usually formed through stretching and heating process [9]. Among these three materials, only PVDF can be prepared by non-solvent induced phase separation (NIPS) method and form asymmetric membrane morphology, which is important for achieving a good permeability [10,11]. Most membranes used for MD so far are originally marketed for microfiltration or ultrafiltration process and these commercial membranes are incompletely adequate for MD because of weak hydrophobicity, poor permeability, low solute rejection, and so on.…”

Metal–Organic Framework-Functionalized Alumina Membranes for Vacuum Membrane Distillation

“…This is because that the alumina membrane not only functions as a solid support, but also the Al source for the growth of MOF. The presence of acetic acid in the reaction solution helps to slowly release the Al source from the membrane surface [23]. Hence, the NH 2 -MIL-53(Al) crystals are intergrown from the alumina surface.…”

“…Usually, high liquid repellence can be obtained with nano-or hierarchical roughness that traps air in between the membrane surface and liquid droplets [23][24][25]. In nature, typical examples of this phenomenon are plant leaves such as the lotus leaf [25], or some insects such as the water strider [26].…”

A hybrid process combining homogeneous catalytic ozonation and membrane distillation for wastewater treatment

“…The detailed hollow fiber fabrication protocol can be found in literature (Hou et al, 2012). The dope solution comprised 15 wt% PVDF (Solef ® PVDF1010, Solvay, Belgium) and 85 wt% dimethylacetamide.…”