Determination of the applicability of the tungsten-containing material as low-cost electrodes for reverse electrodialysis

Abstract

Electrodialysis, especially reverse, is a promising method of water desalination, concentration of solutions, extraction of valuable components from waste and rinse water, and power generation. The main problem is the search for low-cost universal anode-cathode materials. The work aims to determine the possibility of using the VNZh90 superalloy (5 % Ni, 5 % Fe, 90 % W) and the electroplated Ni-W alloy as a universal cathode-anode material for reverse electrodialysis. The crystal structure of the Ni-W alloy was studied by X-ray diffraction analysis; the morphology was studied by scanning electron microscopy. The anodic behavior of both alloys was studied by voltammetry in 6 % HCl in a saturated NaCl solution. The high passivity of the VNZh90 superalloy was revealed. On the repeated anodic curve, the current density of the passivation plateau decreased 2.8 times and was 37 mA/dm2. This indicates that the use of the VNZh90 superalloy is promising as a universal cathode-anode material of a reverse electrodialyzer. The phenomenon of significant passivation for the Ni-W alloy was also revealed. The primary curve of the alloy showed two dissolution peaks and a well-defined passivation plateau. Probably, the first peak corresponded to a more active phase with a low W content. This was confirmed by the absence of the first peak on the repeated anodic curve and the identity of the passivation plateaus of the primary and repeated curves. The passivation current density was 209 mA/dm2. These data also indicate the possibility and prospects of using the electroplated Ni-W alloy as a universal cathode-anode material of a reverse electrodialyzer after optimizing the composition and deposition method of the alloy, as well as reducing the wear rate.