Intercalation of Cocamide Diethanolamine into Swellable Clay by Solid-State Process

Abstract

Coconut fatty acid diethanolamine (cocamide-DEA (CDEA)), CH3(CH2)16CON(CH2CH2OH)2 was intercalated into montmorillonite using both solution and solid-state reaction methods. In a typical solution process, the CDEA aqueous solution was mixed with a montmorillonite (Kunipia-F) aqueous suspension, which resulted in a CDEA–montmorillonite layer complex with a basal spacing of 13.8 Å. A CDEA–montmorillonite complex was also easily prepared by the solid–solid reaction method. A mixture of CDEA and Na–montmorillonite was ground at ambient temperature. The basal spacing of the mixture increased to approximately 44 Å after grinding for 30 min. Upon washing, the basal spacing decreased to approximately 10 Å, which was close to that of pristine Na–montmorillonite owing to the deintercalation of the CDEA molecules. The basal spacing of the CDEA–montmorillonite composite starting from protonated montmorillonite decreased to 13.5 Å upon washing, indicating the parallel monolayer arrangement of CDEA molecules between the silicate layers. This finding strongly suggests that acid–base intralayer complexation is responsible for the solid-state intercalation reaction.