Photocatalytic upcycling of tetrahydrofurfuryl alcohol to highvalue γ-hydroxybutyric acid in radioactive organic wastewater

Nuclear energy has emerged as a vital clean energy source with super-high energy density. As a representative of fourth-generation nuclear reactors, High-Temperature Gas-Cooled Reactor (HTGR) generates substantial amounts of tetrahydrofurfuryl alcohol (THFA)-containing wastewater, for which effective treatment methods are rarely explored. Here, we present a selective and efficient approach employing anatase TiO2 as a photocatalyst to upcycle THFA into γ-hydroxybutyric acid (GHB), which can be used as a valuable bifunctional monomer to successful synthesize biodegradable poly(4-hydroxybutyrate). With optimized TiO2 catalyst, a THFA conversion of 87.6% and a GHB yield of 0.198 g/h/m2 were achieved. It was further elucidated that the •OH radicals generated by UV-excited TiO2 initiate the rapid transformation of THFA into GHB through two parallel pathways and the sluggish oxidation of GHB thereby facilitates its accumulation. The developed flow reactor could lead to the total conversion of THFA with GHB as main product that can be purified and separated, demonstrating the practical feasibility of the proposed strategy. This approach showcases the potential for converting THFA-containing wastewater into high-value chemicals through photocatalysis, offering an eco-friendly solution for THFA-containing wastewater treatment.