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In this paper, the film-solid diffusion model (FSDM) combined with a concentration-dependent surface diffusivity Ds=D0 exp {k(q/qsat)} was presented to describe the kinetics of adsorption of reactive dye from aqueous solution onto activated carbon in a batch reactor. A finite-difference scheme was employed to solve the partial differential equations which govern the entire adsorption process in the batch reactor and the resulting kinetic data was presented in terms of the concentration decay curve. It was found that, for the investigated adsorption system, one set of mass transfer parameters was adequate to describe the adsorption rate at different initial solute concentrations. Compared with the constant surface diffusivity model (CSDM), the concentration-dependent surface diffusivity model (CDSDM) yielded a steeper solid-phase concentration profile due to the concentration dependence of Ds. Parametric sensitivity analysis was also carried out in order to facilitate understanding of the effect of each parameter on the shape of the concentration decay curve. [Copyright &y& Elsevier]

A three dimensional (3D) reduced graphene oxide (rGO)/zeolitic imidazolate framework-67(ZIF-67) aerogel (3D rGO/ZIF-67 aerogel) was prepared via in situ assembly of ZIF-67 polyhedrons on a 3D rGO networks, not only providing multifarious affinity interactions for synergistic promoting the adsorption behavior of organic dyes, but also constructing a holder for ZIF-67 polyhedrons to convenient separation. This porous aerogel displays excellent absorption ability for cationic dyes (crystal violet, CV) and anionic dyes (methyl orange, MO). The maximum adsorption capacities are up to 1714.2 mg·g −1 and 426.3 mg·g −1 for CV and MO, respectively. 3D rGO/ZIF-67 aerogel shows a remarkable promoting of CV adsorption capacity than pure 3D rGO and ZIF-67. The ultrahigh adsorption capability towards cationic CV dyes is mainly driven by π-π interactions and electrostatic interactions between 3D rGO/ZIF-67 aerogel and dye molecules, and synergistic interactions at the interface of 3D rGO and ZIF-67 polyhedrons. The high adsorption capability towards anionic MO dyes is mainly due to the porosity of ZIF-67 polyhedrons and electrostatic attraction between MO and ZIF-67. The multi-component property of 3D rGO/ZIF-67 aerogel shows a great potential application in dye-bearing wastewater treatment. [ABSTRACT FROM AUTHOR]