One-Pot Hydrothermal Synthesis of Victoria Green (Ca3Cr2Si3O12) Nanoparticles in Alkaline Fluids and Its Colour Hue Characterisation

Abstract

One-pot hydrothermal preparation of Ca3Cr2Si3O12 uvarovite nanoparticles under alkaline conditions was investigated for the first time. The experimental parameters selected for the study considered the concentration of the KOH solvent solution (0.01 to 5.0 M), the agitation of the autoclave (50 rpm), and the nominal content of Si4+ (2.2–3.0 mole). Fine uvarovite particles were synthesised at 200 °C after a 3 h interval in a highly concentrated 5.0 M KOH solution. The crystallisation of single-phase Ca3Cr2Si3O12 particles proceeded free of by-products via a one-pot process involving a single-step reaction. KOH solutions below 2.5 M and water hindered the crystallisation of the Ca3Cr2Si3O12 particles. The hydrothermal treatments carried out with stirring (50 rpm) and non-stirring triggered the crystallisation of irregular anhedral particles with average sizes of 8.05 and 12.25 nm, respectively. These particles spontaneously assembled into popcorn-shaped agglomerates with sizes varying from 66 to 156 nm. All the powders prepared by the present method exhibited CIE-L*a*b* values that correspond to the Victoria green colour spectral space and have a high near infrared reflectance property. The particle size and structural crystallinity are factors affecting the Victoria pigment optical properties, such as CIE-L*a*b* values, green tonality, and NIR reflectance.

Effective Elimination of Hazardous Chromium (VI) Using Periodic Elements and Contemporary Adsorption Methods by Using Magnesium Ferrite Nanoparticle: A Review

“…Another green colored Chromium compound is Uvarovite. It is a garnet found in Chromium ore [25]. Chromdravite is another Chromium bearing minerals which is in tourmaline group [26].…”

Editorial for the Special Issue: “Hydrothermal Synthesis of Nanoparticles”

“…An analogous investigation was carried out by Rendon-Angeles et al [7], which focused on the one-step synthesis of Uvarovite NPs (Ca 3 Cr 2 Si 3 O 12 ), in which the singlephase stability depends on the alkaline concentration of the hydrothermal media. The single-step chemical reaction associated with the Ca 3 Cr 2 Si 3 O 12 formation proceeded in a 5 M KOH solution under hydrothermal conditions at 200 • C for 12 h, resulting in the preparation of fine agglomerates with a popcorn-like shape and sizes varying between 66 and 156 nm.…”