USE OF MINERAL PROTON-CONDUCTIVE MEMBRANES FOR ELECTROOSMOTIC FRACTIONATION OF THE HYDROGEN ISOTOPES

Abstract

The operation of the nuclear fuel complex is constantly accompanied by contamination of liquid industrial discharges with tritium. The problem of preventing such pollution is complicated by the fact that the pollutant component (tritium) is an integral part of the aqueous transport substance. Equally important is the need to purify deuterium water used in the nuclear industry from tritium and to increase the efficiency of tritium concentration technologies for further use. The use of the process of electroosmotic fractionation of hydrogen isotopes is proposed for purification of NPP process waters from tritium. In the isotopic molecule of tritiated or deuterium water (“HTO”, “DTO”), the covalent bond D – O and T – O is stronger than H – O, so it is possible to separate the hydrogen isotops by using the electroosmostic method in aqueous solution on composite mineral proton-conducting membranes. Such conductors can provide fractionation of hydrogen isotopes by proton exchange by tunneling or forwarding transport of ions in the process of electroosmosis under the influence of the applied electric field. In order to determine the possibility and efficiency of the electroosmotic process for fractionation of hydrogen isotopes in aqueous solution, we used a three-chamber electroosmotic cell with variable proton-conducting membranes made of mixtures of montmorillonite clay and zeolite (MCZ), montmorillonite and quartz sand (MQS), montmorillonit (MC) and saponite (SC) clays. The anode chambers were filled with electrolyte in the amount of 450–550 cm3, prepared from tritiated water, with a specific activity of 5,950 Bq·dm– 3 with the addition of anhydrous Na2CO3 salt. Under the influence of the electric field, electroosmotic filtration of the dissociated tritiated electrolyte through weakly permeable clay and composite membranes from the anode chamber to the cathode chamber was happening. At the same time, due to the proton conductivity of electroosmotic membranes with increasing strength and voltage of electric current, the alkalinity of the aqueous solution in the cathode chamber increased and the specific activity of tritium in the filtrate (catholyte) decreased by 14–26%. The method is protected by the Patent of Ukraine for a utility model.

Keywords

• ecological and geochemical assessing
• surface water
• shallow groundwater
• trace-element analysis