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Experimental investigation of Congo red dye treatment via capacitive deionization utilizing agro-waste

Karishma Maheshwari, Madhu Agarwal, and A. B. Gupta

Department of Chemical Engineering, Malaviya National Institute of Technology Jaipur, Jaipur, India



Received: 23 August 2021  Accepted: 3 November 2021


Water contamination by Congo red dye (CRD), used in textile industries to impart colour to the fabric, is a ubiquitous environmental issue. Amid substantial advances in the treatment approaches for textile discharges, capacitive deionization (CDI) is the new horizon to the field with energy-efficient statistics. For the first time, this investigation involves removing CRD using CDI via fabricated electrodes using the waste walnut shell (WNS)-derived activated carbon coated over graphite sheets revealing microporous morphologies. The study involves the examination of the varying initial CRD concentration (10–200 mg/L) and electro-sorption time (30–240 min) for capacitive removal on the application of small potential 1.2 V. Moreover, the Langmuir model of isotherm and the second-order kinetics were best fitted to the equilibrium data with R2 of 0.99. The maximum sorption capacity was 140.84 mg/g at a sorption time of 120 min and an inlet concentration of 200 mg/L CRD with potential application of 1.2 V. The process kinetics suggested monolayer formations and the existence of proportionality between dye molecules adsorbed over the electrode’s surface. The mechanism of adsorption has been examined here for capacitive dye removal proposing the deionization of dye molecules due to potential applications around both terminals. To the best of the author’s knowledge, the electrostatic force was the prominent reason behind the sorption of dye molecules. In addition to this, the energy aspects of the process were evaluated, revealing 0.21 kWh of specific energy consumption. Henceforth, the investigation suggests that CDI can be a plausible cost-effective system for treating textile effluents.

Graphical abstract

Keywords: Capacitive removal; Textile effluent; Mechanism; Electrochemical aspects

Full paper is available at

DOI: 10.1007/s11696-021-01973-5


Chemical Papers 76 (5) 3119–3131 (2022)

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