Exploring the surface reactivity of the magnetic layered double hydroxide lithium-aluminum: An alternative material for sorption and catalytic purposes

• Published in: Applied surface science Vol. 467-468; pp. 1195 - 1203
• Main Authors: Mak Yu, Tiffany, Caroline Reis Meira, Ana, Cristina Kreutz, Juliana, Effting, Luciane, Mello Giona, Renata, Gervasoni, Ronald, Amado de Moura, Alexandre, Maestá Bezerra, Fabricio, Bail, Alesandro
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.02.2019
• Subjects: Layered double hydroxide; Magnetite; Point of zero charge; Variable charge density; Point of zero charge; Magnetite; Variable charge density; Layered double hydroxide
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2018.10.221

•A new magnetic LDH was synthesized by the use of cheap and simple procedures.•The lithium caused strong influence in the LDH surface reactivity.•The polarizing effect of the lithium contributed to the increase in the pHPZC.•The magnetic core did not influence the stability of the LDH layer.•Magnetic saturation was inversely proportional to the particle agglomeration. The magnetic layered double hydroxide lithium-aluminum was prepared by the combination of two simple procedures: co-precipitation method for the magnetite and dissolution of aluminum powder under strong basic conditions in order to form the LDH. The magnetic LDH was characterized by powder X-ray diffraction (PXRD), infrared spectroscopy (FTIR), textural analysis, vibrating-sample magnetometry analysis (VSM), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and pH at point of zero charge (pHPZC). It was possible to prepare the LDH on the magnetic particles and evaluate how its surface reactivity was influenced by the lithium ion. Fluoride and selenate ions were used to monitor the surface reactivity related to the Brönsted sites formed by hydroxyl groups. The pHPZC was high indicating that the AlO6 octahedral structural units were strongly influenced by the polarizing effect of the lithium ion. FTIR analysis corroborates the lithium influence on the LDH reactivity, since an absorption band related to the carbonate ion appeared in high wavenumber. Although it was possible to observe the lithium leaching, it seems the composite was able to improve the lithium stability.