Thermal behavior and antibacterial studies of a carbonate Mg–Al-based layered double hydroxide (LDH) for in vivo uses

Abstract

The goal of this work is to study the thermal behavior and the antibacterial properties of a MgAl-CO3 layered double hydroxide (LDH), which demonstrated high efficiency in removing chromium (VI) from contaminated industrial wastewater. The compound has been synthesized via co-precipitation route (direct method) followed by hydrothermal treatment, obtaining nanoscopic crystallites with a partially disordered (turbostratic) structure. After its synthesis, the compound was characterized by means of X-ray powder diffraction, field emission scanning electron microscope, inductively coupled plasma atomic emission spectroscopy and analysis and Fourier transform infrared spectroscopy. On the other hand, with the view to check the drug delivery and surgical tools usage of MgAl-CO3, antibacterial tests, performed according to the Kirby–Bauer method, revealed the inability the growth of the pathogenic bacterial strains. Thermogravimetry and differential thermal analysis revealed that evolution of water from the material occurs in two stages upon heating and a noticeable interaction takes place between water (in the vapor phase) and MgAl-CO3. Kinetic analysis of both steps provides almost constant values of activation energy, with the following average values in the range 0.1 < a < 0.9: E1 = (66 ± 9) kJ mol‒1; E2 = (106 ± 7) kJ mol‒1. Finally, prediction of reasonable reaction times extrapolated at 25 and 37 °C has been made from kinetic parameters of the first step, while almost unrealistic reaction time values were determined using the same procedure with kinetic parameters related to the second step.