Characterization and adsorption properties of the electrolytic carbon derived from CO^sub 2^ conversion in molten salts

The amorphous carbon derived from a “molten salt CO2 capture and electrochemical transformation” process, was characterized and studied for the adsorption of aqueous solutes. XRF and TG measurements showed that the electrolytic carbon (E-carbon) had a higher purity than the commonly available biochars and activated carbons due to its unique growth mechanism in molten salts. The analysis on morphology, diameter distribution and porosity indicated that the E-carbon, with an inhomogeneous porous structure, exhibited an average particle size of 9.8 μm in aqueous solution, and a BET surface area of 614 m2 g−1. The major surface oxygen-containing functional group for E-carbon was carboxyl group, which was primarily due to the cathodic deoxygenation of carbonate ions and the surface modifying effect of melt. The spontaneous Cu(II) adsorption by E-carbon followed the pseudo-second-order kinetic model and the Langmuir isotherm. Through the surface complexation and surface-precipitation processes, the E-carbon exhibited a maximum adsorptive capacity of 29.9 mg g−1 for Cu (II) adsorption. It also showed a good performance on methylene blue adsorption due to its favorable adsorption-related features, such as high purity, porosity and having a large number of surface functional groups. The E-carbon is envisaged to be used as an adsorptive material for decontamination.