Adsorption of reactive orange 13 onto jackfruit seed flakes in aqueous solution

• Adsorption of RO13 onto jackfruit seed flakes was investigated in aqueous solution.
• Adsorption kinetics follows pseudo second-order model.
• Intraparticle diffusion and film diffusion are the rate limiting steps.
• Equilibrium adsorption behaviors follows Langmuir isotherm model.
• The present adsorption is spontaneous and endothermic physisorption process.

The adsorption of reactive orange 13 (RO13) onto jackfruit seed flakes was investigated in aqueous solution at different pHs, initial concentration of dye solutions, ionic strengths and temperatures, respectively. The adsorbent and dye adsorption were characterized by diffuse reflectance electronic absorption and Fourier transformation infrared (FTIR) spectra. The adsorption of RO13 increased largely with decreasing solution pH or with increasing initial dye concentration. Pseudo first-, second-order, intraparticle, and film diffusion kinetic models were used to evaluate experimental data obtained from batch studies, and thereby elucidate the kinetics and mechanism of adsorption process. The results showed that the adsorption of RO13 follows pseudo second-order kinetics very well. The intraparticle diffusion and film diffusion are the rate limiting steps. The equilibrium adsorption data were analyzed by Temkin, Freundlich and Langmuir isotherm models, respectively. The best fit to the data was obtained from the Langmuir model. The monolayer adsorption capacity of jackfruit seed flakes was found to be 64.10 μmol/g at pH 2. The values of activation and thermodynamic parameters were calculated and obtained results revealed that the present adsorption is a spontaneous and endothermic physisorption process.