Development of CO2-Responsive Draw Solution for Trace Antibiotic Wastewater Treatment

Abstract The detection of trace antibiotics in aquatic environments poses a critical global challenge, threatening both ecological safety and public health. Forward osmosis (FO) membrane separation technology has emerged as a highly efficient approach for purification of trace antibiotics, characterized by high treatment efficiency and low energy consumption. However, challenges inherent to the recycling of draw solutions restrict the development of FO technology. Herein, we report the synthesis and application of a novel CO 2 -responsive SiO 2 @PDEA nanocomposite as a highly recyclable particulate draw solution. This system leverages CO 2 /heat-triggered reversible switching between hydrophilicity and hydrophobicity to enable facile recovery. The 6 wt% SiO 2 @PDEA solution leads to a significantly enhanced water flux ( J w ) to 5.31 LMH (PRO mode), a threefold increase over bare SiO 2 . Crucially, the ratio of reverse solute flux ( J s ) to J w was minimized to 0.015 g/L, providing a substantial cost advantage over inorganic salts. The efficiency of this approach enabled a threefold concentration of tetracycline. Furthermore, the solution demonstrated outstanding cyclic stability with a solute recovery rate consistently exceeding 99% via mild thermal stimulation. These findings demonstrate that SiO 2 @PDEA is an exceptionally efficient, sustainable, and cost-effective draw solution with substantial potential for the practical remediation of trace antibiotic-containing wastewater.