Removal of Thiophene and 4,6-Dimethyldibenzothiophene by Adsorption on Different Kinds of Starches

The desulfurization by adsorption of thiophene and 4,6-dimethyldibenzothiophene on unripe banana starch, dessert banana starch, corn starch, and porous corn starch was studied. The adsorbents were characterized by scanning electron microscopy, surface acidity measurement, and infrared spectroscopy with attenuated total reflection. The results showed low values of adsorption of both sulfur molecules on both banana starches, which is due to the absence of cavities or pores in their structure. In the case of corn starch, the presence of cavities or pores allows a greater adsorption capacity for thiophene and 4,6-dimethyldibenzothiophene. The mechanism of interaction between sulfured molecules and the starches can occur through free electron pair of sulfur or the pi electron cloud of the aromatic ring with the Bronsted acid site of starches. The enzymatic modification applied to corn starch allowed obtaining a material with a greater number of cavities or pores, but that maintains their structure and physicochemical properties. The presence of pores of a larger size allows adsorbing a greater amount of sulfured molecules in comparison to the native starch.