Acid-activation assisted by microwave of a Brazilian bentonite and its activity in the bleaching of soybean oil

• Bentonite from Brazil was activated by microwave.
• The bleaching capacity of the sample for the soybean oil was determined.
• Pore size of clay particles showed some contribution on the oil bleaching capacity.
• Mechanism of β-carotene adsorption into particle pore was proposed.
• Interplay between shear and thrusting along the arc.

In this work, a bentonite clay from Brazil was activated with H2SO4 (6 N) by microwave operating at different powers for 15 min. Physical and structural changes on the clay were observed after the microwave treatment. These changes were measured by X-ray diffraction (XRD), specific surface area (SSA) and atomic force microscopy (AFM) techniques. The bleaching capacity of each sample for the alkali-refined soybean oil was determined. It was observed that the average pore size of clay particles showed some contribution on the oil bleaching capacity, and that is not associated with maximum SSA. A mechanism of soybean oil bleaching by β-carotene molecule adsorption into particle pore of bentonite was proposed.