A Study of Promising Carbon Sorbents Prepared via High-Temperature Activation in Purification Processes of Aqueous Solutions from Dyes

The sorption capacity of a highly porous carbon material obtained via high-temperature alkaline activation and activation with additional steam treatment was found. The resulting activated highly porous carbon material possessed a specific surface area of 2600–2700 m²/g and a pore volume of more than 1.3 cm³/g. High sorption activity was revealed relative to methylene blue (1075, 1865, and 2010 mg/g for carbonizate, AC-1, and AC-2, respectively) and the sunset (66, 934, and 972 mg/g for carbonizate, AC-1, and AC-2, respectively) organic dyes. The time to reach sorption equilibrium for the sorbents was found to be from 15 to 30 min. The resulting kinetic data were processed with pseudo-first-order and pseudo-second-order, Elovich, and intraparticle diffusion models. The pseudo-second-order model provided the highest correlation coefficients R² (when methylene blue dye molecules are removed, R² for AC-2, AC-1, and carbonizate are 1, 1, and 0.9999, respectively; when sunset dye molecules are removed, R² for AC-2, AC-1, and carbonizate are 1, 0.9999, and 0.9994, respectively). It was found that the chemical interaction proceeds between dye molecules and functional groups of a sorbent. It was revealed that the activated carbon material can serve as a highly effective absorber of organic pollutants from aqueous solutions.