Effective transport properties for the pyridine-granular activated carbon adsorption system

In this work, the kinetics of pyridine adsorption onto granular activated carbon was studied from the point of view of an up-scaling process by using the method of volume averaging. The pore and surface effective diffusivities were estimated by supposing simple microscale geometries (ordered media of cylinders and spheres) and those of images processed from SEM (Scanning Electron Microscopy) micrographs. In addition, as a rough estimate, the point surface diffusivity is reported. The results revealed that the up-scaled diffusional model satisfactorily interpreted the concentration decay curves and the effective diffusivity was found to be an increasing function of the concentration, mainly due to the contribution of surface diffusion. In general, the diffusivity coefficients involved in the adsorption system are related through the expression molecular diffusivity = 22 × point surface diffusivity = 5/2 × pore effective diffusivity = 1/12 × surface effective diffusivity.

Granular activated carbon; Method of volume averaging; Pore and surface effective diffusion; Pyridine adsorption Activated carbon adsorption; Adsorption system; Concentration decay curves; Diffusivity coefficient; Effective diffusion; Effective diffusivities; Effective transport properties; Granular activated carbons; Increasing functions; Micro-scales; Molecular diffusivity; Pyridine adsorption; Surface diffusivity; Upscaling; Volume-averaging; Granular materials; Pyridine; Scanning electron microscopy; Surface diffusion; Transport properties; Adsorption

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