Mesoporous bio-materials synthesized with corn and potato starches applied in CO2 capture

Abstract

The development of environmentally friendly techniques to obtain mesoporous solids allows the construction of new and better materials, making potential use of natural resources. In this study, mesoporous silica with high specific surface area and controlled porosity is synthesized by a novel and facile method, which employs potato or corn starches as directing structure agent. Using SEM microscopy, the ellipsoidal morphology of potato starch and the irregular and polygonal shape of corn starch were determined. Pattern A and B were identified by XRD, corresponding to samples of cereals and tubers, respectively. The stages of gelatinization and retrogradation of the starches were studied, obtaining mesoporous silicas with type IV adsorption/desorption isotherms and specific surface areas of 708.6 m2 g−1 with potato starch and 1018.1 m2 g−1 with corn starch for short gelatinization times (4 h, 353 K) and long retrogradation (14 h, 298 K). In addition, the use of HCl solution promoted the hydrolysis of starch in its monomeric unit (glucose) and the consequent bimolecular nucleophilic substitution with silica. The materials obtained presented a random mesoporous order and a CO2 adsorption capacity at 373 K in the range between 150.2 and 131.4 mg CO2 g−1.