Porous carbon material prepared from Na2EDTA and its performance in capacitive deionization process

Abstract Porous carbon materials were synthesized by a simple one-step pyrolysis of disodium ethylenediamine tetraacetate (Na2EDTA) under different temperature (650, 750 and 850 °C). Several characterization technologies were employed to evaluate the as-synthesized samples. Cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy tests were carried out to study the electrochemical property of the samples. The capacitive deionization (CDI) performance of the three samples-based electrodes was investigated and compared. The obtained results showed that pyrolysis temperature played a key role in the formation of the final products with different pore structure and heteroatom content, such as nitrogen and oxygen. Electrochemical performance measurement revealed that 750 °C sample exhibited the highest specific capacitance, the smallest diffusive resistance and charge-transfer resistance, and good conductivity. The salt electrosorption capacity of 750 °C samples were 8.02 mg g−1 at a low initial concentration of NaCl solution (25 mg L−1) and 27.75 mg g−1 at a high initial concentration of NaCl (500 mg L−1). The outstanding CDI performance of 750 °C material can be contributed to its high specific surface area and suitable pore structure. As a low-cost and processable precursor, Na2EDTA exhibited promising application prospect in large-scale CDI process.