Effect of fiber surface functionalization on adsorption behavior of uranium from seawater desalination brine

Inspired by the easy availability and modification of fiber-like materials for water treatment and sorption applications, the functionalized natural fiber luffa cylindrica (LC) and synthetic fiber polyacrylonitrile (PAN) have been designed for the uranium adsorption. Seawater desalination brine has a significantly higher concentration of uranyl ion, so it is very meaningful to extract uranyl ions from it. In this paper, the seawater from seawater desalination plant at various treatment stages was collected to evaluate uranium adsorption performance. The effect of flocculant and scale inhibitors on uranium adsorption performance of functional fibers was also studied. The oxime/guanidine co-modified luffa cylindrica fiber (WGLC), guanidine/amidoxime co-modified polyacrylonitrile fiber (PAN-G-AO) and polyethyleneimine modified polyacrylonitrile fiber (PAN-PEI) were synthesized. PAN-G-AO showed excellent uranium capture performance with a high saturation adsorption capacity of 490.20 mg g⁻¹ and rapid adsorption equilibrium at 15 min. Amount of uranium adsorption of three materials declined when flocculant and scale inhibitors were added. The results of adsorption experiments in various stages of seawater desalination solution for 30 days showed that adsorption materials PAN-G-AO had the largest adsorption capacity (18.6 μg g⁻¹) in the concentrated desalinated seawater, which demonstrate promising application potential of the functionalized fiber materials for uranium adsorption from desalinated concentrated seawater.