An amyloid-like proteinaceous adsorbent for uranium extraction from aqueous medium

Abstract

The most current developed uranium adsorbents usually suffer from relatively low adsorption capacity, poor selectivity, high cost, nondegradability and secondary environmental pollution issues. Therefore, it is urgent to develop an environmentally friendly bio-adsorbent with high adsorption performance and cost efficiency. Here, we prepare a proteinaceous adsorbent (phase-transitioned lysozyme-β-cyclodextrin, PTL-β-CD) through amyloid-like aggregation in aqueous solution under ambient conditions. The PTL-β-CD composed of micro-particles can effectively extract uranium ions from aqueous medium with a high adsorption ratio of 95.05%; and notably, the adsorption capacity per unit area is calculated to be 1.405 mg g⁻¹ m⁻², which is 3–90 times greater than that of the ion exchange resins, active carbon (AC), covalent organic frameworks (COFs) and metal organic frameworks (MOFs). High selectivity towards uranium ions in the presence of both common cations and anions is simultaneously obtained; In particular, the adsorption ratio is nearly 80 times higher than that of the competitive vanadium ions. It is demonstrated that the PTL-β-CD adsorbs uranium ions mainly through electrostatic interaction and surface complexation (i.e., host–guest interaction between the hydrophobic internal cavities of β-CD and uranium ions, and metal chelation interaction between the surface hydroxyls of β-CD and uranium ions). Both lysozyme and β-cyclodextrin are cheap and easily available commercial chemicals, so the total cost of this proteinaceous adsorbent is only $0.42 per g. Notably, the good biocompatibility and enzymatic degradability indicate that the PTL-β-CD is friendly to the environment and ecosystem. This novel green and facile approach shows great promise for the mass production of eco-friendly proteinaceous adsorbents to efficiently recover uranium ions from aqueous medium.