Adsorptive Removal of Basic Yellow Dye Using Bigadiç Zeolites: FTIR Analysis, Kinetics, and Isotherms Modeling

Abstract

The adsorptive removal efficiency of Basic Yellow Dye (Astrazon Yellow 7GLL) from aqueous solutions was studied using different types of modified zeolites in an agitated single‐stage batch experimental system. Zeolite samples consisted of mainly clinoptilolite, collected from Bigadic Region of Turkey. The optimum adsorbent amount was found as 0.5 g in the primary experiments. Then, the adsorption kinetics with a constant initial dye concentration of 50 mg/L, agitation speed of 250 rpm, and temperature of 25°C for a period of 180 min were investigated. Three kinetic models namely, pseudo‐first‐order, pseudo‐second‐order non‐linear kinetic models, and the intra‐particle diffusion were used to describe the kinetic data of adsorption process. Non‐linear fittings of the Langmuir and Freundlich adsorption isotherm models were applied to the experimental equilibrium data obtained with dye concentrations in the range of 12–550 mg/L. The adsorption capacities (Qo) of zeolite samples for basic dye were in the range of 17.8–21.2 mg/g. Different analytical methods were used to investigate the influence of the different treatments on the zeolite surface and understanding of the adsorptive removal of dye using natural and modified zeolites. It was concluded that the spectroscopic results agree with the results obtained by kinetic and adsorption experiments as the acidic pre‐treatment zeolite has the highest removal rate for dye molecules since the concentration of various active sites (oxygen species, free Al+, and Si+ sides, etc.) to increase on the surface. On the contrary, basic treatment causes the loading of the surfaces with hydroxyl groups and these interact with each other via H‐bond and causes increased removal rate. © 2018 American Institute of Chemical Engineers Environ Prog, 38: S185–S195, 2019