Recyclable aptamer-derived aqueous two-phase flotation for high-efficiency separation of mercury(II) ions modulated by aggregation states

Developing an efficient and economical strategy for selective removal of toxic ions drives exploration of separation technology. In this respect, aqueous two-phase flotation (ATPF) is a promising technology, but for practical separation, it is restricted by low selectivity and difficult recycling of collector. Herein, we constructed aptamer-derived ATPF that could address these fundamental limitations by using aptamer-functionalized thermo-responsive polymers as collectors. Collector, PEG113-b-P(NIPAM90-co-HBMA3)-P (TBC-P), was relied on specific and reversible coordination interactions between aptamers and Hg(II) ions, and simple separation by thermally precipitating, achieving the highly efficient separation of Hg(II) ions and recycling of collector. Singlefactor experiments were carried out first to determine the critical variables in influencing the removal of Hg(II) ions. Response surface methodology (RSM) was further conducted to optimize the removal conditions. Statistical analysis indicated that the quadratic models was significant, and could be utilized to determine optimum process conditions. Under the optimum process conditions, separation efficiency and partition coefficient for Hg(II) ions displayed by ATPF were 97.22% and 3.47, respectively. The collectors and phase-forming components were easily recovered, and then recycled to maintain 70% of its initial separation efficiency and 50% of its initial partition coefficient in the fifth cycle. This satisfactory result verifies aptamer-derived ATPF is a feasible and practical method, providing a great guarantee for pollutant treatment to ensure sustainable environment.

Automated summary

The study introduces an aptamer-derived aqueous two-phase flotation (ATPF) technology using aptamer-functionalized thermo-responsive polymers as collectors for efficient separation and recycling of Hg(II) ions. After optimization, the ATPF exhibited excellent separation efficiency and partition coefficient, with the collectors and phase-forming components easily recovered for multiple cycles, showing its potential as a practical method for sustainable environmental pollutant treatment.