Modelling and optimization of tyrosine adsorption onto nanozeolite beta

In this study, the capabilities of response surface methodology (RSM) for modeling and optimization of uptake capacity of nano-zeolite beta were investigated. Firstly, nano-zeolite beta was synthesized and characterized by X-ray technique. As an example, the crystalline size of synthesized nano-zeolite beta was calculated to be 27 nm using Debye-Scherrer equation. Then, batch experiments of tyrosine adsorption were performed in 25 treatment runs using central composite design by Design-Expert 8.0.7.1 software. The effects of four independent variables in a defined range of pH (3-7), initial dye concentration (2-30 mg/L), adsorbent dosage (0.01-0.05 g) and contact time (15-45 min) were evaluated on the adsorption capacity. Result indicated that maximum uptake capacity of nano-zeolite beta for tyrosine was happened in pH of 3 with contact time of 45 min and adsorbent dosage of 0.01 g. The isotherm data were analyzed by the Langmuir and Freundlich isotherm models. The better fit for the equilibrium process was Langmuir model indicating multi-layer adsorption. The kinetic studies indicated that the adsorption followed the pseudo second-order kinetic model. The capacity of nano-zeolite beta for adsorption of tyrosine was too much and it can be used for adsorption of this amino acid in the clinical samples.