Impacts of operating conditions and solution chemistry on osmotic membrane structure and performance

Wong, Mavis C.Y.; Martinez, Kristina; Ramon, Guy Z.; Hoek, Eric M.V.

Impacts of operating conditions and solution chemistry on osmotic membrane structure and performance

Type

Article

Authors

Wong, Mavis C.Y.
Martinez, Kristina
Ramon, Guy Z.
Hoek, Eric M.V.

KAUST Grant Number

KUS-C1-018-02

Date

2012-02

Abstract

Herein, we report on changes in the performance of a commercial cellulose triacetate (CTA) membrane, imparted by varied operating conditions and solution chemistries. Changes to feed and draw solution flow rate did not significantly alter the CTA membrane's water permeability, salt permeability, or membrane structural parameter when operated with the membrane skin layer facing the draw solution (PRO-mode). However, water and salt permeability increased with increasing feed or draw solution temperature, while the membrane structural parameter decreased with increasing draw solution, possibly due to changes in polymer intermolecular interactions. High ionic strength draw solutions may de-swell the CTA membrane via charge neutralization, which resulted in lower water permeability, higher salt permeability, and lower structural parameter. This observed trend was further exacerbated by the presence of divalent cations which tends to swell the polymer to a greater extent. Finally, the calculated CTA membrane's structural parameter was lower and less sensitive to external factors when operated in PRO-mode, but highly sensitive to the same factors when the skin layer faced the feed solution (FO-mode), presumably due to swelling/de-swelling of the saturated porous substructure by the draw solution. This is a first attempt aimed at systematically evaluating the changes in performance of the CTA membrane due to operating conditions and solution chemistry, shedding new insight into the possible advantages and disadvantages of this material in certain applications. © 2011 Elsevier B.V.

Citation

Wong MCY, Martinez K, Ramon GZ, Hoek EMV (2012) Impacts of operating conditions and solution chemistry on osmotic membrane structure and performance. Desalination 287: 340–349. Available: http://dx.doi.org/10.1016/j.desal.2011.10.013.

Acknowledgements

The work presented in this publication was supported by Award No. KUS-C1-018-02, made by King Abdullah University of Science and Technology (KAUST). GZR was supported by a Vaadia-BARD Post-doctoral Fellowship Award No. FI-435-2010 from BARD, The United States-Israel Binational Agricultural Research and Development Fund.