XAS time-resolved phase speciation of the LDH: from the decomposition to the regeneration

• Grant number: 14/24882-5
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: March 01, 2015
• End date: May 31, 2015
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Celso Valentim Santilli
• Grantee: Rodrigo Morais Menezes dos Santos
• Supervisor: Valérie Briois
• Host Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Institution abroad: SOLEIL Synchrotron, France
• Associated to the scholarship: 13/25043-4 - Layered double hydroxides-derived materials: synthesis, characterization and application in adsorption and advanced oxidation processes, BP.MS

Abstract

Layered Double Hydroxides (LDH) and their thermal decomposed products have received much attention in the past decades due to important applications in several fields, like as treatment of contaminated wastewater with high removal efficiency and low costs. One interesting effect of these material when decomposed at low temperatures (T < 500 °C), is the capability to recover the layered structure after contact with water or anionic solutions. This property, known as memory effect, allows significant improvements in adsorption capacity and catalytic processes. The main purpose of this project is give conclusive evidences of the mechanisms explaining this interesting phenomenon, which remains a topic of intense debate. The XAS time-resolved method is a powerful tool to in-situ monitoring of the chemical environment changes occurring during the material processing, being suitable to follow the evolution of several metastable intermediates during the thermal decomposition and the memory effect of layered double hydroxides (LDH). During the BEPE we intent to use the excellent time resolution of the Quick-EXAFS technique to access all species involved during thermal decomposition and subsequent regeneration process. The identification of intermediate species together with the evolution of profiles of concentration of all the species should give conclusive evidences of mechanisms involved in the LDH memory effect. The investigation of different anions showing different thermal properties allocated into the interlayer space, and the use of different regeneration media will also contribute to clarify the mechanisms involved. (AU)