Fluid‐Solid Adsorption in Batch and Continuous Processing: A Review and Insights into Modeling

Abstract

Adsorption is a highly versatile separation technique that can be used both for product separation and waste purification, involving selective interaction of one or more compounds from the liquid phase on a solid called adsorbent. In literature, several models have been proposed to describe both the kinetics and the equilibrium data of different systems. These models are relevant for fluid-solid adsorption and fluid-solid reactions. Kinetic models can be classified in either pseudo-kinetic or diffusive models. Most of them cannot be applied directly in simulating the behavior of continuous columns, while others are applicable only in a narrow range of experimental conditions. The performances of a general continuous adsorption model have been tested by performing a dedicated parametric investigation with the aim to give an overview of how the parameters affect the continuous operation

Char from Spent Tire Rubber: A Potential Adsorbent of Remazol Yellow Dye

“…The obtained parameters from the models are presented in Table 3. The results showed that the experimental data were better adjusted to the Langmuir model, suggesting that the adsorption occurred through a monolayer process [23]. The maximum RY uptake capacity was 11.9 mg/g, which is comparable or even slightly higher to the performance of other adsorbent materials, such as zeolites and biomass fly ashes as reported in literature (Table 4).…”

“…where q e is the adsorbent removal capacity in the equilibrium (mg/g), q max is the maximum uptake capacity or the monolayer capacity (mg/g), K L is the Langmuir's constant (L/mg), C e is the concentration of RY in the equilibrium (mg/L), K F is the Freundlich's constant (mg (1−1/n) L 1/n /g) and 1 n is the adsorption intensity (dimensionless). The Langmuir model assumes that the active sites on the surface are energetically homogeneous; once a sorbate molecule occupies a site, no further adsorption can take place at that site [23]. Thus, there is no interaction among molecules adsorbed on adjacent or near sites, and the phenomenon runs until the complete formation of the monolayer; adsorption is localized, and the energy needed for the process does not depend on the coverage degree.…”

“…Thus, there is no interaction among molecules adsorbed on adjacent or near sites, and the phenomenon runs until the complete formation of the monolayer; adsorption is localized, and the energy needed for the process does not depend on the coverage degree. The Freundlich model conceives an energetic heterogeneity of the active sites, considering multilayer formation [23].…”

Synthesis and Characterization of Active Carbon-Titanium Dioxide Composite

“…Separation occurs because differences in molecular weight, form or polar reason few particles to be held strongly over the surface from others. In many cases, the adsorbate is held strongly enough to allow complete removal of that component of fluid [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. In industry, there are several adsorbent materials are used to purify water.…”

“…Activated carbon consists of a wide network of pores of molecular size within the carbon particles, and non-planar layers of carbon (with some linear or single bonded carbons), which limits the proximity of the adsorbed atoms or molecules. The surface area within the pores of activated carbon is a boundary condition [12][13][14]. Electron density determines when the pore shape is curved.…”