(714g) Membrane Degradation of Forward Osmosis (FO) in Treating MED Brine: Comparison between Cellulose Triacetate (CTA) and Thin-Film Composite (TFC) Polyamide Membranes | AIChE

(714g) Membrane Degradation of Forward Osmosis (FO) in Treating MED Brine: Comparison between Cellulose Triacetate (CTA) and Thin-Film Composite (TFC) Polyamide Membranes

Authors 

Yang, Y. - Presenter, East China University of Science and Technology
Sun, Y., East China University of Science and Technology
Yu, J., East China University of Science and Technology

Membrane degradation of forward osmosis (FO) in
treating multi-effect distillation (MED) brine: comparison between cellulose
triacetate (CTA) and thin-film composite (TFC) polyamide membranes

Ye Yang (speaker) , Yuzhu Sun*,
Jianguo Yu*

State Key Laboratory of Chemical
Engineering, College of Chemical Engineering, East China University of Science
and Technology, Shanghai 200237, China

Abstract

The discharge of reject
brine from thermal desalination processes is a threat to marine ecosystems
because of its high salinity, high temperature, and chemical dosages. In
this research, the forward osmosis (FO)
was used to treat multi-effect distillation (MED) brine. The changes in surface
chemical properties of two commercial forward osmosis (FO) membranes resulting
from exposure to MED brine for 30 days was characterized via X-ray
photoelectron spectroscopy (XPS), Fourier-transform
infrared spectroscopy (FTIR), Contact angle and zeta potential. The
permeability (P), forward solute flux (FSF) and specific reverse solute flux
(SRSF) were measured to evaluate the membrane performance degradation. Besides,
the extended Derjaguin¨CLandau¨CVerwey¨COverbeek (XDLVO) approach was used to
predict the changes in the membrane
fouling propensity. The results showed that the cellulose triacetate (CTA)
membrane suffered deacetylation and chain
cleavage due to the alkaline condition of the MED brine, while the polyamide
thin-film composite (PA-TFC) membrane experienced degrafting of poly(sulfobetaine methacrylate) (pSBMA) brushes due
to the high temperature. The selectivity reductions of both membranes were
observed according to the increased FSF and SRSF. Moreover, the results
indicated that CTA membrane fouling of sodium alginate (SA) was ameliorated as
the attractive XDLVO interaction energies decreased, which was attributed to
the increased hydrophilicity caused by the CTA hydrolysis. On the contrary, the fouling resistance of the PA-TFC
membrane was severely reduced as the attractive interaction energies increased,
which was resulted from the exfoliation of pSBMA brushes. This study reveals
the necessity for the further design and fabrication of the FO membrane with long-term stability
against MED brine.

Keywords: forward osmosis,
degradation, brine

Graphic Abstract