Dye biosorption from water employing chemically modified calabrian pine cone shell as an effective biosorbent

The feasibility of base (0.1 M NaOH) treated cone shell of Calabrian pine as an effective and inexpensive biosorbent was examined for removal of C.I. Basic Red 46 as a model azo dye from aqueous solution. Biosorption conditions selected for this study were optimized using Taguchi experimental design. The pseudo‐first‐order, pseudo‐second‐order, logistic, and intraparticle diffusion models were used for the evaluation of kinetic data. The logistic model presented the best fit to the experimental results with the most suitable statistical outcomes. The intraparticle diffusion was not the only rate‐limiting step for the dye biosorption and also the other mechanism(s) may control the rate of biosorption or all of which may be operating simultaneously. Furthermore, the relationship between the kinetic parameters and the biosorption performance was investigated. The equilibrium data were analyzed using Freundlich, Langmuir, and Dubinin‐Radushkevich isotherm models. Langmuir model fitted better to the biosorption data than Freundlich model. The maximum monolayer biosorption capacity of the biosorbent for the dye was found to be 89.76 mg g −1 . Besides, when compared with the natural cone shell, the chemically modified cone shell has a greater biosorption capacity for C.I. Basic Red 46. The base modification improved the biosorption ability of the biosorbent for the dye. Dubinin‐Radushkevich model and the standard Gibbs free energy change presented that the predominant mechanism of the biosorption of dye by the cone shell was likely physical biosorption. Finally, a single‐stage batch biosorption system design for the dye removal was outlined based on the equilibrium data obtained. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1267–1278, 2015