The multi-functional system of electrochemical desalination, RhB degradation and Cr (VI) removal

ABSTRACT

Capacitive deionisation (CDI), as a novel electrochemical technology, has attracted a fast-growing research interest over the past years. However, the single function of salt removal limits further development of conventional CDI systems. Herein, we propose a multi-function CDI device, which can achieve the electrochemical desalination, degradation of organic pollutants and removal of heavy metal ions through the redox electrocatalytic deionisation technology. Sulphur-doped reduced graphene oxide (S@rGO) is utilised as the anode to catalyse the degradation of rhodamine B. The Pt-coated graphite paper is used as a cathode for the removal of dichromate ions by the electro-reduction process. The voltage plateau of S@rGO is reduced by ∼0.35 V compared with the pure carbon cloth electrode, indicating the effectiveness of S@rGO as the catalyser. The salt feed is desalted to ∼0.74 mS·cm⁻¹ level at a current density of 1 mA·cm⁻². The degradation efficiency of rhodamine B (RhB) and potassium dichromate are 99.1% and 55.3%, respectively. The effects of different current densities and cycling are also investigated. This work is significant for the multi-functional process of water treatment and the device design.

Synopsis

: The single function of salt removal limits the further development of the CDI system. A multi-function CDI device is proposed to achieve electrochemical desalination, organics degradation and dichromate ion removal.

GRAPHICAL ABSTRACT

KEYWORDS:

• Electrochemical desalination
• electrocatalyst degradation
• S@rGO composite
• degradation of the organic pollutant
• removal of heavy metal ion

Disclosure statement

No potential conflict of interest was reported by the author(s).

Credit author statement

Yuchao Zhu: Device design, Experiment, Methodology, Data analysis, Investigation, preparation, Writing- Original draft. Qiang Wei: Conceptualised the work, Device design, Experiment, Methodology, Data analysis, Investigation, preparation, Writing- Reviewing and Editing. Qinyu He: Investigation, Methodology. Deyang Chen: Discussion and analysis of the supplemented experiments. Than Zaw Oo: Data analysis, Supervision, Paper writing and Editing. Su Htike Aung: Data analysis, Supervision, Paper writing, Project administration, Funding acquisition. Fuming Chen: Conceptualised the work, Data analysis, wrote the paper, Supervision, Project administration, Funding acquisition.

Data availability statements

Data are available on request to the authors.

The table of contents entry

A multi-function CDI device is proposed, which can achieve the electrochemical desalination, degradation of organic pollutants and removal of heavy metal ions through the redox electrocatalytic deionisation technology.

Additional information

Funding

This project was supported by the National Key Research and Development Programme of China (2019YFE0198000), the Science and Technology Programme of Guangzhou (2019050001), National Natural Science Foundation of China (U1832104, 51972122；51672090 and 91963102), the Department of Education of Guangdong Province (2019KZDXM014), SCNU Outstanding Young Scholar Project (8S0256), F. Chen acknowledges the High-End Foreign Experts Project (G2021030016L) and Pearl River Talent Programme (2019QN01L951). The author gratefully acknowledges the support of the 2022 International (Regional) Cooperation and Exchange Programmes of SCNU (8S043502).