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Characterization and adsorption properties of the electrolytic carbon derived from CO2 conversion in molten salts

Mao, Xuhui, Yan, Zhiping, Sheng, Tian, Gao, Muxing, Zhu, Hua, Xiao, Wei, Wang, Dihua
Carbon 2017 v.111 pp. 162-172
activated carbon, adsorption, aqueous solutions, biochar, carbon dioxide, copper, decontamination, electrochemistry, ions, kinetics, melting, methylene blue, particle size, porosity, salts, solutes, sorption isotherms, surface area
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.