The draw solution is the driving force of the forward osmosis (FO) process; however, the solute loss of the draw solute to the feed side is a general, financial limitation for most applications. The anthropogenic amino acid ethylenediaminetetraacetic acid (EDTA) was investigated as a draw solution for FO. At concentrations of approximately 1.0 osmol/kg, EDTA demonstrated comparable water fluxes (Jv = 5.29 L/m2 h) to the commonly used salt, NaCl (Jv = 4.86 L/m2 h), and both produced better water fluxes than glucose (Jv = 3.46 L/m2 h). EDTA showed the lowest solute loss with Js (reverse solute loss or solute leakage) = 0.54 g/m2 h. The molecular weight, degree of ionisation and charge of EDTA played a major role in this efficiency and EDTA was therefore well rejected by the membrane, showing a low Js/Jv ratio of 0.10 g/L. Owing to the low solute loss of EDTA and its resistance to biodegradation, this compound has the potential to be used as a draw solute for FO during long periods without requiring much replenishment.
EDTA: a synthetic draw solute for forward osmosis
Kerusha Lutchmiah, Jan W. Post, Luuk C. Rietveld, Emile R. Cornelissen; EDTA: a synthetic draw solute for forward osmosis. Water Sci Technol 1 November 2014; 70 (10): 1677–1682. doi: https://doi.org/10.2166/wst.2014.424
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