Evaluation of the Structural Integrity of Layered Double Hydroxides and Mesoporous Silica During the Preparation of Heterostructures

Author(s)

Bianconi, Lister P. ; Taviot-Gueho, Christine ; Constantino, Vera Regina L. ; Bizeto, Marcos Augusto

• Document type: Journal article
• Source: Journal of the Brazilian Chemical Society; v. N/A, p. 8-pg., 2022-03-08.

Abstract

Heterostructures constructed with mesoporous silica and layered double hydroxides are interesting for catalytic and drug delivery applications. Different arrangements between these phases are possible. In this study, we prepared heterostructures by embedding layered double hydroxides phases [M4Al2(OH)(12)](CO3) (M = Mg2+ or Zn2+) within the MCM41 mesoporous silica type phase. According to our results, the most critical step of this preparation is the removal of the organic template used to create the mesopores in the silica phase, which can be done by calcination or extraction with solvent, normally a mixture of ethanol and a mineral acid. The results reported in this study demonstrate that both can cause structural changes in the components of the heterostructure at different extensions. Calcination promoted the collapse of the layered hydroxide phases. Attempts made for their reconstruction through rehydration, which is a quite known process, were not completely effective and also dependent on the chemical composition of the layered phase. The complete template removal with preservation of the layered phases was possible using the extraction method but by replacing the mineral acid with NH4Cl. However, some discrete structural changes were identified possibly due to a partial lixiviation of Al3+ from the double hydroxide layers. (AU)

• FAPESP's process: 19/05467-0 - Preparation of functional mesoporous silica for intracellular controle release of bioactive species
• Grantee: Marcos Augusto Bizeto
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/50317-9 - Biocompatible nanovectors based on hybrid lamellar materials and composites with polymers for drug release
• Grantee: Vera Regina Leopoldo Constantino
• Support Opportunities: Regular Research Grants