Studies On Electrodepositing Of Liquid-solid Fluidized Beds Electrode Containing Binary Mixed Particles

Fluidized bed electrode (FBE) combines the fluidization techniques and electrochemical methods. When using FBE to treat waste water with metal ions, the absence of added chemicals and the direct recovery of metal will not bring a secondary pollution; because of the large specific surface area and high mass transfer rate between the solid and liquid phase, it would greatly weaken the concentration polarization and electrochemical polarization to obtain the higher current efficiency. When FBE containing binary (or multifold) mixed particles, on the one hand, the quality of fluidization could be enhanced; on the other hand, there have poignant collision in particles, so that mass transfer rate, current efficiency and space-time benefit could receive definite advance than use FBE which containing single types of particles.In this work, a rectangular fluidized bed with 50×15mm cross-section has been used to study the fluidized behavior of the spherical copper particles both in a single size and a binary mixed size, with water as a fluidized medium, under room temperature. In the case of the single-sized particles, can calculate bed voidage by Richardson-Zaki function; while in the case of the binary mixture, bed voidage could be well illustrated by modificatory voidage-averaging model.Furthermore, FBE which containing single types of particles was investigated in the diluent copper sulphate solutions, so that influences to the electrolysis process have been researched systematically. It has been resulted that when groovy voltage was controlled at 2.3V, the current efficiency and instantaneous deposition velocity achieved maximum rate; there has existed a proper expansion ratio range, it was 20%-30% in these experimental conditions, in which high current efficiency and deposition velocity could be obtained; it was benefited to electrolysis when electrolyte has rich concentration of copper ions or particles' diameter is larger. Based on these investigations, FBE containing binary mixed particles was investigated. Experimental results indicated that when the value of diameter ratio was suitable, in these experimental conditions under 1.58, the instantaneous deposition velocity of FBE which containing binary particle mixtures higher than FBE which only containing single size particles.Finally, through the theoretical analysis and regress experimental data, the experimental functions to determine the mass transfer coefficient and the instantaneous deposition velocity have been figured out, so built a good foundation for further in-depth study.