Electric Field-Assisted Uptake of Hexavalent Chromium Ions with In Situ Regeneration of Carbon Monolith Adsorbents.

The uptake of hexavalent chromium (Cr(VI)) ions from wastewater is of great significance for environmental remediation and resource utilization. In this study, a self-designed instrument equipped with an oxidized mesoporous carbon monolith (o-MCM) as an electro-adsorbent is developed. o-MCM with a super hydrophilic surface displayed a high specific surface area (up to 686.5 m2  g-1 ). With the assistance of an electric field (0.5 V), the removal capacity of Cr(VI) ions is as high as 126.6 mg g-1 , much higher than that without an electric field (49.5 mg g-1 ). During this process, no reduction reaction of Cr(VI) to Cr(III) ions is observed. After adsorption, the reverse electrode with 10 V is used to efficiently desorb the ions on the carbon surface. Meanwhile, the in situ regeneration of carbon adsorbents can be obtained even after ten recycles. On this basis, the enrichment of Cr(VI) ions in a special solution is achieved with the assistance of an electric field. This work lays a foundation for the uptake of heavy metal ions from wastewater with the assistance of the electric field.