Preparation of nano-alumina trihydroxide by carbonation with surfactants in non-Newtonian fluid

The viscosity of the suspension evolved to a viscous non-Newtonian fluid during carbonation precipitation of the nano-alumina trihydroxide (ATH). The high viscosity affected mass transfer and carbonation process evidently. At high viscosity, conventional methods improved mass transfer less than viscosity breaking. Therefore, the surfactants were selected by improving the fluidity of nano-ATH filter cake, among which a polycarboxylate plus CTAB led to a concentrated caustic ATH suspension of 40 wt% content with good fluidity under current experimental conditions, i.e. pH > 12 and [Na+] = 2.7 mol L−1. The surfactants in the carbonation reaction strongly reduced the suspension's viscosity, resulting in the shortening of reaction time and the increment of productivity. TGA and FTIR results demonstrated that the nano-ATH adsorbed 1.2 wt% of the surfactants in dry mass, and that the nano-ATH was hexagon-shaped slice with good dispersion and uniform distribution with a size of ca. 100 nm × 10 nm.