Traditional approaches for the detection of trace-level alpha-emitting radioisotopes in water require lengthy offsite sample preparations and do not lend themselves to rapid quantification. Therefore, a novel platform is needed that combines onsite purification, concentration, and isotopic screening with a fieldable detection system. In this presentation, we will describe the development of reactive membranes for isolation and concentration of uranium from various aqueous matrices, including high-salinity seawater. The aim was to develop a field portable screening method for the rapid quantification of isotopic distribution by alpha spectroscopy. The reactive membranes were prepared from ultrafiltration membranes by modifying their surfaces to add uranium-selective functional groups. The membrane surfaces were characterized with scanning electron microscopy to gain insight on pore size and atomic force microscopy to analyze surface roughness. Pressure-assisted filtration of uranium solutions was used to load uranium onto the reactive membranes, which subsequently were used as substrates for alpha spectroscopy. Flowthrough uptake experiments were conducted to evaluate the effects of flow rate, membrane support, and modification conditions on sample preparation time and peak energy resolution. The experimental breakthrough data were fitted to a theoretical model to determine the maximum binding capacities and sorption rate constants. Alpha spectroscopy pulse height spectra were analyzed, and excellent resolution with full width at half-maximum values from 30 to 49 keV were recorded, comparable to the results obtained from electrodeposited standard which range from 31 to 36 keV. This membrane-based purification and quantification method enables the rapid, fieldable screening analysis of radionuclides in water for environmental monitoring studies and nuclear forensics investigations.

Development of reactive membranes for the rapid quantification of radionuclides in water

ACS Spring Meeting 2021

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