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Direct contact membrane distillation for effective concentration of perfluoroalkyl substances – Impact of surface fouling and material stability

journal contribution
posted on 2020-09-01, 00:00 authored by Xiao Chen, Anbu VanangamudiAnbu Vanangamudi, jingshi Wang, J Jegatheesan, V Mishra, R Sharma, S R Gray, J Kujawa, W Kujawski, F Wicaksana, Ludovic DumeeLudovic Dumee
Polyfluoroalkyl and perfluoroalkyl substances (PFAS) are ecotoxic amphiphilic compounds containing alkyl-fluorinated chains terminated with weak acid moieties, and hence difficult to be degraded or removed from water sources. Direct contact membrane distillation (DCMD) was used for concentrating and removing of perfluoropentanoic acid (PFPeA) compounds from model contaminated water using commercially available poly (tetrafluoroethylene) (PTFE) membranes. The membranes were characterised for surface morphology, roughness, contact angle and pore size distribution before and after the DCMD test to investigate and evaluate membrane fouling. During the DCMD test performed for 6 h using 10 ppm PFPeA solution, the membrane exhibited progressive increased flux (from 17 to 43 kg m−2 h−1) and decreased PFPeA rejection (from 85 to 58%), as the feed temperature was increased from 50 to 70 °C. Further, the feed/retentate side showed a 1.8, 2.1 and 2.8-fold increase in PFPeA concentration tested at feed temperatures 50, 60, and 70 °C, respectively. The permeate side contained less than 1 ppm of PFPeA revealing that the PFPeA moved across the PTFE membrane during DCMD, which is attributed to progressive surface diffusion over time. This study opens a new route to concentrate and remove amphiphilic molecules, such as PFAS, from source points, relevant to landfill leachates or surface waters. The study also points at gaps in materials science and surface engineering to be tackled to deal with PFAS compounds efficiently.

History

Journal

Water research

Volume

182

Article number

116010

Pagination

1 - 10

Publisher

Elsevier

Location

Amsterdam, The Netherlands

ISSN

0043-1354

eISSN

1879-2448

Language

eng

Publication classification

C1 Refereed article in a scholarly journal; C Journal article