Physicochemical Features of the Sorption of 4-Hydroxy-3-Methoxybenzaldehyde by Norit GAC 1240W Activated Carbon Under Static Conditions

Equilibrium characteristics of the sorption of 4-hydroxy-3-methoxybenzaldehyde (vanillin) by Norit GAC 1240W activated carbon are studied at different temperatures. It is found that the sorption of this substituted hydroxybenzaldehyde by activated carbon is of a monomolecular character in the investigated range of temperatures and is described by the Langmuir equation. Values of the thermodynamic characteristics of the sorption of vanillin by the given sorbent are obtained, and it is established that the process is exothermic. It is shown that when the considered hydroxybenzaldehyde is sorbed by granular Norit activated carbon, the entropy factor makes a key contribution to the free energy of the process. The effect temperature has on the kinetics of vanillin sorption is investigated, and the time to reach equilibrium in the sorbent–sorbate system is determined. It is established experimentally that the stage of external diffusion of the sorbate limits the sorption of vanillin by Norit activated carbon throughout the studied range of temperatures.