Ultrasound-assisted forward osmosis desalination using inorganic draw solutes

Muhammad Qasim; Faisal W Khudhur; Ahmed Aidan; Naif A Darwish

doi:10.1016/j.ultsonch.2019.104810

Ultrasound-assisted forward osmosis desalination using inorganic draw solutes

Ultrason Sonochem. 2020 Mar:61:104810. doi: 10.1016/j.ultsonch.2019.104810. Epub 2019 Sep 28.

Authors

Muhammad Qasim¹, Faisal W Khudhur¹, Ahmed Aidan¹, Naif A Darwish²

Affiliations

¹ Department of Chemical Engineering, American University of Sharjah, P.O. Box 26666, Sharjah, United Arab Emirates.
² Department of Chemical Engineering, American University of Sharjah, P.O. Box 26666, Sharjah, United Arab Emirates. Electronic address: ndarwish@aus.edu.

PMID: 31670249
DOI: 10.1016/j.ultsonch.2019.104810

Abstract

Internal concentration polarization (ICP) represents a serious challenge in forward osmosis (FO) desalination since it causes a significant decline in the water flux across the membrane. Mitigation of ICP is cumbersome since the phenomenon occurs within the membrane porous support layer and mitigation procedures such as inducing turbulence or changing the hydrodynamic conditions tend to be ineffective. In this study, the effect of 40 kHz ultrasound on FO desalination of synthesized brackish and seawater was investigated. The studied process utilizes two different inorganic draw solutes (magnesium and copper sulfate) that are available commercially, can generate high osmotic pressures, and can be easily separated from the product water. Different concentrations of the draw solutions were considered. Results show that the applied ultrasound was effective in partially mitigating the ICP effects and enhancing the water flux. Depending on the feed and the draw solution concentration, flux enhancements of up to 34.6% and 43.9% were observed with magnesium sulfate and copper sulfate draw solution, respectively. In addition, it was observed that the effect of ultrasound on flux enhancement was more evident at lower draw solution concentrations. Although water flux was enhanced, ultrasound resulted in an increased reverse draw solute flux across the membrane.

Keywords: Concentration polarization; Desalination; Draw solution; Forward osmosis; Ultrasound.