Premium
Film‐surface diffusion during the adsorption of acid dyes onto activated carbon
Author(s) -
Choy KKH,
Porter JF,
McKay G
Publication year - 2004
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.1101
Subject(s) - mass transfer , orthogonal collocation , diffusion , adsorption , activated carbon , surface diffusion , langmuir adsorption model , thermodynamics , phase (matter) , chemistry , diffusion equation , carbon fibers , mass transfer coefficient , materials science , differential equation , collocation method , chromatography , mathematical analysis , mathematics , physics , organic chemistry , ordinary differential equation , composite material , service (business) , composite number , economics , economy
A mass transport model has been developed and applied to the adsorption of three acid dyes onto activated carbon in three single component systems. The mass transfer model is based on two rate controlling mass transfer steps, namely external film mass transfer and homogeneous solid‐phase surface diffusion (HSD). Almost all previous film‐HSD models have been based on numerical solutions to the diffusion equation using orthogonal collocation or Crank–Nicolson finite difference solutions. However, in the present model a semi‐analytical solution to the solid surface diffusion equation is presented, yielding a sophisticated solution of the differential equations. The solutions provide a good correlation between the experimental concentration–time decay curves by incorporating the Langmuir equilibrium isotherm to describe the solid phase surface dye concentrations. However, the surface diffusivities show a dependence on the carbon particle surface coverage and these diffusivities have been correlated using a Darken relationship. Copyright © 2004 Society of Chemical Industry