Novel carboxyethyl amine sodium salts as draw solutes with superior forward osmosis performance

A series of carboxyethyl amine sodium salts (CASSs) with different carboxyl group numbers are synthesized as draw solutes for forward osmosis (FO) application. Their chemical structures are examined by 1 HNMR and HRMS. FO performances are investigated and compared in terms of different physicochemical properties. The effects of the CASS concentration on the osmotic pressure and viscosity of the draw solutions, as well as the resulted FO performance are also systematically investigated. A high water flux of 23.07 LMH and an acceptable reverse salt flux of 0.75 gMH can be achieved with 0.5 g mL −1 triethylenetetramine hexapropionic acid sodium (TTHP‐Na) draw solution under PRO mode, which is superior to most other draw solutes reported in previous literatures. TTHP‐Na draw solution is further evaluated to recycle the Congo red solution via FO process to examine its applicability for waste water treatment.