High-concentration ɛ-Al 13 nanoclusters sol prepared by chemical synthesis and membrane distillation concentration process

Abstract

ɛ-Al 13 (AlO 4Al 12(OH) 24(H 2O) 12 7+) is a tridecameric polymer with a 1–2 nm-sized aluminum polyoxocation. The sol with a high concentration of 80% ɛ-Al 13 (2.0 M total Al concentration) is prepared by use of chemical synthesis and membrane distillation (MD) concentration process. The ɛ-Al 13 or Al b content in the final sol is highly influenced by the pH of the synthesized sol. As the MD proceeds, the pH of the synthesized sol increases and Al c or Al 30 decomposes into oligomers which belong to Al b but not ɛ-Al 13. Therefore, the content of Al b increases but the content of ɛ-Al 13 remains constant.