Rapid and continuous synthesis of cobalt aluminate nanoparticles under subcritical hydrothermal conditions with in-situ surface modification

• DOI: 10.1016/j.ces.2012.01.061
• Publication Date: 2012-02-13T10:54:07Z
• Authors: Jinfeng Lu; Kimitaka Minami; Seiichi Takami; Tadafumi Adschiri
• Keywords: Surface Modification; Aluminate

Abstract The synthesis and in-situ organic surface modification of spinel cobalt aluminate nanoparticles were carried out under subcritical reducing hydrothermal conditions (250 °C, 30 MPa). Single nanoparticles of cobalt aluminate were obtained using a continuous flow-type reactor; in contrast, Co 1− x Al x layered double hydroxide (Co-Al-LDHs) became the main product when a batch-type reactor was used. The addition of a surface modifier, hexanoic acid, to the flow-type reaction system changed the hydrophilic surface of the nanoparticles to a hydrophobic surface. Cobalt aluminate nanoparticles modified with hexanoic acid were well dispersed in hexane. The in-situ surface modification during the synthesis of the nanoparticles reduced the particle size from 15 nm to 10 nm.