Adsorption Behavior of Organic Dyes in Biopolymers Impregnated with H3PO4: Thermodynamic and Equilibrium Studies

A lignocellulose‐based waste biopolymer was impregnated with phosphoric acid and used for the removal of two organic dyes, Direct Blue (DB) and Reactive Blue (RB), from aqueous solution. Batch adsorption kinetic studies were carried out at different initial concentrations of the dyes, at different t...

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Bibliographic Details
Published in:Chemical engineering & technology 2011-09, Vol.34 (9), p.1459-1467
Main Authors: Senthilkumaar, S., Kalaamani, P., Subburamaan, C. V., Subramaniam, N. G., Kang, T. W.
Format: Article
Language:English
Subjects:
Adsorption
Applied sciences
Biopolymer
Chemical engineering
Diffusion
Entropy of activation
Exact sciences and technology
Heat and mass transfer. Packings, plates
Kinetics
Organic dyes
Process design
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Summary:A lignocellulose‐based waste biopolymer was impregnated with phosphoric acid and used for the removal of two organic dyes, Direct Blue (DB) and Reactive Blue (RB), from aqueous solution. Batch adsorption kinetic studies were carried out at different initial concentrations of the dyes, at different temperatures and various initial pH values (2–10). The equilibrium data obeyed the Langmuir isotherm model with high regression coefficient. The kinetic data were also used to test three different kinetic models. The validity of the kinetic models was analyzed and the pseudo‐second‐order model may be the best fit to explain the rate‐determining step. Adsorption of both dyes follows chemisorption. The effective diffusion coefficient and the activation energy were also calculated at different temperatures to establish the mechanism. Thermodynamic studies suggest that the adsorption of DB and RB is highly endothermic in nature. Mass transfer analysis reveals that the adsorption of DB and RB occurs through a film diffusion mechanism. Based on the Langmuir isotherm equation, the single‐stage batch absorber design of the adsorption of DB and RB onto activated carbon was studied. A phosphoric acid‐impregnated agricultural biopolymer was prepared and its adsorption capacity was evaluated using the organic dyes Direct Blue and Reactive Blue. Equilibrium data were tested for different kinetic models. Thermodynamic parameters were calculated, which suggested the endothermic and spontaneous nature of the process.
ISSN:0930-7516
1521-4125
DOI:10.1002/ceat.201000535