Highly efficient extraction of thorium from aqueous solution by fungal mycelium-based microspheres fabricated via immobilization

In this paper, a facile immobilization method was applied to load alginate, ferric oxide and dopamine onto fungal mycelium to prepare a series of spherical composites as potential adsorbents for the separation and removal of thorium from aqueous solution. The structure and chemical properties of the as-prepared adsorbents were characterized in detail via scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), pH value at the point of zero charge (pHPZC) and thermogravimetric (TG) analysis. Based on the adsorption studies, the magnetic gamma-ferric oxide (γ-Fe2O3) and polydopamine (PDA) cofunctionalized fungal microspheres (FPFMs) exhibited excellent adsorption performance for thorium and could represent convenient agents for the removal and recovery of thorium. The equilibrium adsorption data for the FPFMs were well fitted by the Langmuir model, and a high maximum thorium adsorption capacity of 326.346 mg·g−1 was obtained. The thermodynamic parameter values (ΔH0 > 0, ΔS0 > 0, ΔG0 < 0) demonstrated that the thorium adsorption process was feasible, endothermic and spontaneous in nature. This work indicated that FPFMs have great potential to be employed as effective adsorbents for practical industrial water pollution treatment. Importantly, the possible mechanism of thorium adsorption on the homogeneous surface of FPFMs represented a combination of chelation interactions, coordination and ion exchange.