Preparation of nanosized chromium carbonate and chromium oxide green pigment through direct carbonation and precursor thermal decomposition

Abstract

Chromium carbonate nanoparticles were prepared through the direct precipitation method. Due to the importance of improving the capability and quality of a process for adjusting size of the product particles the optimal precipitation reaction parameters were evaluated using the parameter design of the Taguchi method. Reaction conditions like the concentrations of the reacting species, the rate of the addition of the reagent as well as the reactor temperature were optimized using the orthogonal array design. It was concluded from the results that chromium carbonate nanoparticles can be synthesized via direct carbonation process while controlling the concentrations of chromium and carbonate ion solutions and the reaction temperature. Further, a one-step thermal decomposition method was used for the efficient conversion of chromium carbonate to chromium oxide nanoparticles. The characterization studies of the products were performed through X-ray diffraction, scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy and thermal analysis techniques.