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- Title
Hindered diffusion of heavy metal cations in the adsorption rate on activated carbon fiber.
- Authors
Valdez-García, Genesis Derith; Leyva-Ramos, Roberto
- Abstract
Water resource pollution caused by heavy metals represents a risk to the environment because of their toxicity. Adsorption on activated carbon materials can be applied to remove heavy metals in aqueous solutions. Activated carbon fiber (ACF) is a microporous material successfully used for adsorbing heavy metals from water solutions; however, the adsorption rate on ACF has yet to be investigated in detail. The adsorption equilibrium and rate of Cd(II), Ni(II) and Zn(II) on ACF were analyzed in this study, and the experimental data were procured in a differential packed bed batch adsorber. The Radke-Prausnitz isotherm successfully interpreted the experimental adsorption equilibrium data. The adsorption rate was analyzed employing a diffusional model, supposing that the external mass transfer along with intraparticle or intrafiber diffusion affect the overall adsorption rate. Besides, the metal intrafiber diffusion was attributed exclusively to diffusion in the pores volume, excluding surface diffusion. The results revealed that intrafiber diffusion is significantly affected by hindered diffusion caused by frictional effects on pore walls (K r), steric exclusion (K p), and blocking provoked by metal cations adsorbed onto pore walls (K a). The hindrance factors K r and K p were estimated using literature correlations, and K a was related to the mass of metal adsorbed. • Adsorption of Cd(II), Ni(II) and Zn(II) on activated carbon fiber (ACF) was studied. • Pore Volume Diffusion Model interpreted metal cation adsorption rate on ACF. • Hindered diffusion greatly affected the intraparticle diffusion of metal cations. • Hindrance was by steric exclusion, wall friction and obstruction by metal adsorbed.
- Subjects
CARBON fibers; ADSORPTION (Chemistry); KIRKENDALL effect; HEAVY metal toxicology; HEAVY metals; ANALYSIS of heavy metals; SURFACE diffusion; ACTIVATED carbon
- Publication
Chemical Engineering Research & Design: Transactions of the Institution of Chemical Engineers Part A, 2023, Vol 196, p556
- ISSN
0263-8762
- Publication type
Article
- DOI
10.1016/j.cherd.2023.07.005