Thermoresponsive solid-liquid phase separation of the PEtOx/GO composite system for efficient recovery of uranium from wastewater

Abstract

A novel poly(2-ethyl-2-oxazoline) (PEtOx)/graphene oxide (GO) composite system has been developed for removal of uranium ions (U(VI)) from waste water via a solid-liquid phase separation. The phase separation of the composite system is triggered by temperatures higher than the low critical solution temperature (LCST) of PEtOx, producing a solution phase and a sedimentation phase. In this process, GO sheets can be fully transferred to the sedimentation, enabling efficient separation from solution. Since both GO and PEtOx can chelate strongly with U(VI) by having abundant oxygen-containing groups, such a phase separation process can be used to efficiently adsorb and enrich U(VI) in the sedimentation via a synergistic process, and the sedimentation can then be easily separated from solution. Compared to traditional liquid phase extraction system, the PEtOx/GO composite system has several advantages in U(VI) recovery. First, it is more environment-friendly by avoiding use of organic solvent. Second, the solid-liquid phase separation is advantageous for easy waste separation and recycling use of the adsorbent. Moreover, the system can be used in more harsh conditions such as low pH, high pH and high salt concentration. This study paves an innovative way for the development of novel methods for efficient U(VI) separation and recovery.