Anti-scaling electrode and environmental application of reverse electrodialysis

Abstract

this has a serious effect on ong-term stability in RED stack. To date, a detailed scaling mechanism and effective anti-scaling approaches have not been suggested. This study is the first to report findings that scale formation strongly depends on the structural morphology and surface chemistry of catalytic materials in a cathode. The nano-scaled Pt/C with a thin and porous foam-like $Mg(OH)_2$ was four times more effective with anti-scaling than the bulk Pt thin film with thick and dense film-like $Mg(OH)_2$ In using a higher cell paired RED stack (≥300 cell pairs) with higher voltage, the surface-modified carbon nanostructures demonstrated anti-scaling behaviors that were superior to the Pt-based catalysts. In particular, O-rich functionalized carbon treated by acid and air plasma formed a one-dimensional $Mg(OH)_2$ nanostructure. The results indicate that the highly acidified surface leads to the growth of an orientated $Mg(OH)_2$ nanostructure, facilitating stable catalytic activity and charge transport over an extended period of time compared to other types of cathodes. The long-term test showed that the RED performance was stable at 35.12 $A/m^2$ for 12 h for ≥300 cell pairs

This study demonstrated an anti-scaling strategy during the cathodic reaction of a large-scaled reverse electrodialysis (RED) stack for a variety of carbon-based cathodes. The scaling phenomena in the RED stack are a result of the conversion of multi-valent ions that migrate from seawater to the cathode through a shielding membrane into inorganic forms such as hydroxides and/or carbonates

this was compatible with the Pt/C catalysts with scales. These anti-scaling carbon electrodes were also applied for the on-site electrochemical production of hydrogen peroxide via a cathodic reaction during the production of chlorine-based oxidizing species using an anodic reaction. Both oxidants were observed to almost completely disinfect aquaculture wastewater within a short period of time, exhibiting a stable power production of 0.1 $W/m^2$ with a specific energy of 0.01 $kWh/m^3$ during the 680 h operation. These results offer a meaningful solution for the commercialization of RED along with other electrochemical systems under natural seawater conditions.