Performance of a functionalised polymer-coated silica at treating uranium contaminated groundwater from a Hungarian mine site

Abstract

The performance of an active material for treating uranium contaminated groundwater within a permeable reactive barrier (PRB) is reported. This material, called PANSIL, has a tailored ligand system that selectively removes the uranyl (UO 2 2+) cation from solution. The active uranyl ligand in PANSIL is a polyacryloamidoxime resin derived from polyacrylonitrile, which is deposited from solution onto the surface of quartz sand to form a thin film coating.PANSIL is effective at sequestering cationic and neutral uranyl species when the solution pH is above 4, due to the stability of the polyacryloamidoxime-uranyl complex formed. However the rate of sequestration decreases rapidly when the pH exceeds about 8 where neutral uranyl species are present only at very low concentrations. It can preferentially sequester UO 2 2+ in the presence of typical divalent groundwater cations. In mildly alkaline conditions the sequestration performance in groundwater is sensitive to the concentration of uranyl complexing ligands, such as bicarbonate. Such behaviour has important consequences for PRB design as it will determine the barrier thickness required to treat a particular groundwater flow rate.1

Configuration of Non-Pumping Reactive Wells Considering Minimum Well Spacing

“…Groundwater containing soluble contaminants encounters the reactive material in the PRB and passes through it, resulting in the removal of the contaminants. PRB technology has been applied to treat groundwater contaminated with heavy metals [6][7][8], nutrients [9][10][11], radionuclide [12], petroleum hydrocarbons [13][14][15], and chlorinated solvents [16][17][18].…”

“…The reactive material should be physically stable, chemically reactive, and hydraulically permeable for long periods in subsurface environments. Various studies have been conducted on nano-zero-valent iron [19], sulfidized nanoscale zerovalent iron [20], zeolite [21], aminated electrospun nanofiber membrane [22], sodium alginate/graphene oxide [23], functionalized silica [12], natural pyrite [24], etc. as reactive materials.…”

Uranyl Ions Uptake from Aqueous Solutions Using Crosslinked Ionic Copolymers Based on 2-Acrylamido-2-Methylpropane Sulfonic Acid Copolymers

“…[2] The high ion selectivity of chelating exchanger is attributed not only to electrostatic forces but also to coordination bonds in metal-chelating groups. Coordination resins have been used in metal extraction, [3] but they demonstrate poor swelling in water which affected the mobility of ligands. In this respect, hydrophilic polymeric networks containing amide, amine, carboxylic acid and ammonium groups, will be very advantageous, as they can absorb large amounts of water and bind metal ions.…”