Interaction and stabilization of DMF-based alumina suspensions with citric acid

The understanding of the detailed interaction between particles and dispersants in non-aqueous solutions is important for industrial applications. Herein, we report the investigation on the alumina suspension with citric acid in N,N′-dimethylformamide (DMF). The interaction was characterized by monitoring the evolution of UV–vis spectra, zeta potential values, and FT-IR spectra. The dispersion stability was examined by sedimentation test. It is found that the adsorption of citric acid on the surface of alumina particles depends on the apparent pH (pHa) values of the solution. The adsorption follows the Langmuir type. The DMF-based alumina suspension exhibits a high stability due to the adsorption of citric acid on alumina particles, and shows the highest stability at pHa 2.6 where the maximum adsorption occurs for citric acid.