The potential use of ultrasound-assisted bleaching in removing heavy metals and pigments from soybean oil using kinetic, thermodynamic and equilibrium modeling

Abstract

In this research, the sorption behavior (kinetic, isotherm, and thermodynamic modeling) of heavy metals (Cu (II) and Fe (II)) and pigments (carotenoid and chlorophyll) onto activated bentonite clay was investigated for soybean oil under industrial (IBM) and ultrasonic bleaching method (UBM). A nonlinear fitting approach was used to determine the best-fit isotherm and kinetic models by two statistical criteria including the coefficient of determination (R²) and chi-square (χ²). The adsorption of metal ions and pigments onto activated bentonite clay under UBM was quite well by the pseudo-first-order model. In both bleaching methods, the equilibrium adsorption data follows the Toth isotherm model, presenting the sorption occurrence tends to be on a heterogeneous surface. The results indicated that the adsorption thermodynamics was endothermic in nature and the process was spontaneous between 35 and 65 °C.

Keywords: Adsorption; Bentonite clay; Endothermic; Freundlich; Modeling.