Abstract:
In this paper, we present the results of liquid low-level radioactive wastes (LLLRW) treatment by direct contact
membrane distillation (DCMD) using polyethylene terephthalate (PET) track-etched membranes (TeMs). PET
TeMs were modified by styrene and triethoxyvinylsilane (TEVS) using UV-induced grafting. Modification led to
increase in the contact angle to 99° of PET TeMs (pore size from 150 to 300 nm). Hydrophobic PET TeMs were
investigated by X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), goniometric analysis, gas permeability test, liquid entry presser (LEP) analysis and scanning electron microscope
(SEM). Prepared membranes were tested in treatment of LLLRW by DCMD. The influence of pore size on water
flux and rejection degree was studied. Rejection degree was evaluated by conductometry and atomic emission
methods. Decontamination factors (evaluated by gamma-ray spectroscopy) for 60Co, 137Cs, and 241Am were
found to be 85, 1900 and 5 respectively. In most cases degree of rejection of Cs, Mo, Sr, Sb, Al, Ca, Fe, K, Mg and
Na ions were more than 90% and close to 100%. The use of TeMs with a narrow pores size distribution and
without tortuous channels allowed us to achieve better purification from radioactive wastes in comparison with
hollow-fiber membranes.
