Adsorption characteristics of modified bentonites for purification of anthocyanin from saffron tepal

In this study, anthocyanin was extracted from saffron tepals utilizing the ultrasound-assisted extraction method. The adsorbents of raw bentonite (RB), acid activation of bentonite (AA) thermal activation of bentonite (TA), and acid and thermal activation of bentonite (ATA) were employed to separate anthocyanin from solution. The influence of the operating parameters was evaluated. The isotherm study demonstrated that anthocyanin adsorption on adsorbents could be fitted better by the Langmuir equation than the Freundlich equation. A good agreement between the predicted consequences of the pseudo-second-order model and empirical data was provided. Thermodynamic parameters indicated that anthocyanin was adsorbed in an exothermic and physical process. Findings presented that the best adsorption performance of anthocyanin related to ATA with 2.25 mg/g adsorption capacity which was more than 1.55, 1.75, 1.88 mg/g for RB, AA, and TA, respectively. It was due mainly to the increased surface area by both thermal and acid activation of raw bentonite.