Effect of dry-out on the fouling of PVDF and PTFE membranes under conditions simulating intermittent seawater membrane distillation (SWMD)

Elena Guillen-Burrieza, Rinku Thomas, Bilal Mansoor, Daniel Johnson, Nidal Hilal, Hassan Arafat

Research output: Contribution to journalArticlepeer-review

Abstract

Hydrophobic membranes are perceived to be chemically stable and resistant to dry-out during intermittent membrane distillation (MD) operations. However, distillate quality deterioration has been reported in field tests of solar-powered MD systems. This work investigates the effects of salt deposition, resulting from membrane dry-out, on the properties of two types of commercial hydrophobic membranes commonly used for MD purposes. The membranes are made of polytetrafluoroethylene (PTFE) and polyvinylidenefluoride (PVDF). The intermittent operation was simulated by a series of wet/dry cycles using seawater at MD operational temperatures. Membrane properties including surface contact angle, gas permeability, and mechanical strength were assessed, along with other structural characteristics like pore size distribution. The morphology of the salt-exposed membranes was also investigated using SEM and EDS. Atomic force microscopy (AFM) measurements were carried out to assess surface morphology and quantify surface roughness, in relation to the fouling process. AFM was combined with the use of a CaCO3 colloid probe to assess adhesion forces between CaCO3 and the membranes. DCMD experiments were conducted to study the post-fouling performance of the membranes in the MD process. Significant scaling was detected starting from the first week of seawater exposure, as evidenced by all the characterization techniques used. PVDF and PTFE membranes were observed to behave somewhat differently under these fouling conditions. DCMD experiments proved that membrane wetting was exacerbated by intermittent operation.

Original languageEnglish (US)
Pages (from-to)126-139
Number of pages14
JournalJournal of Membrane Science
Volume438
DOIs
StatePublished - Jul 1 2013

Keywords

  • Fouling
  • Intermittent operation
  • Membrane distillation
  • Membrane dry-out
  • Membrane wetting

ASJC Scopus subject areas

  • Biochemistry
  • Materials Science(all)
  • Physical and Theoretical Chemistry
  • Filtration and Separation

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