NUMERICAL MODEL OF THE ELECTRODEPOSITION PROCESS FOR STRONTIUM REMOVAL FROM WATER

The impact of the spatial arrangement of electrodes and their electric potential was analysed, as well as the position and intensity of the sink/source in a recirculating electrochemical (EC) device (reactor) for purifying water with increased strontium concentration.The used method was numerical modelling, with a calibration of the parameters of the numerical model based on the measurements on a laboratory device with the same geometric characteristics and boundary conditions. In the implementation of numerical simulations, two layouts using a total of 8 aluminium electrodes were analysed. 4 cathodes (C) and 4 anodes (A) were arranged in two blocks (C-AA-C and A-C-C-A; C-A-C-A and C-A-C-A), two sink positions, and intensities of sink/source ranging from 0.05 l/s to 0.5 l/s. The presence of strontium ions in water (Sr2+) was interpreted as particles with a charge of 3.2 center dot 10-19 C and diameter of 1.2 center dot 10-8 m, which, through the coupling of the hydrodynamic and electrostatic 3D model, are transported through the model domain and/or retained on the electrode plates. The quantification of the effect of a particular tested configuration variant is expressed as the ratio of the number of model strontium particles that are permanently retained on the electrodes and that are summarily introduced into the device during the simulation period. The results of the research conducted on the recirculating EC device show that the efficiency of purification primarily depends on the source/sink intensity, and the arrangement of the electrodes and the position of the sink secondarily. According to the results of the numerical model, the electrode configurations C-A-A-C and A-C-C-A are 7% more efficient than C-A-C-A and C-A-C-A. At the lowest measured source and sink flow rate (Q = 0.05 l/s), the effect of strontium retention on the electrodes is 2.5 times higher than in the case of the highest source and sink flow rate (Q = 0.5 l/s).The position of the sink located right next to the edge of the dividing wall results in 8% less accumulation of strontium on the electrodes than in the case when the sink is placed at a greater distance from the dividing wall. Applying a different voltage to individual pairs of electrodes results in a lower consumption of electricity (33%) and a more uniform distribution of strontium accumulation on the electrodes; however, the removal effect is reduced by 31%.