A green process to prepare chromic oxide green pigment

Area of Science:

• Materials Science
• Inorganic Chemistry
• Green Chemistry

Background:

• Chromic oxide green pigment is a widely used inorganic pigment.
• Traditional preparation methods can involve environmental concerns regarding chromium.
• Developing sustainable and efficient synthesis routes is crucial.

Purpose of the Study:

• To develop an optimized hydrogen reduction and activated sintering process for chromic oxide green pigment.
• To investigate the key factors influencing pigment quality and the underlying preparation mechanism.
• To evaluate the environmental benefits and resource efficiency of the proposed green process.

Main Methods:

• Hydrogen reduction and activated sintering.
• Inductively Coupled Plasma (ICP) analysis.
• X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM).
• Fourier Transform Infrared (FT-IR) spectroscopy.
• UV-Vis spectroscopy and CIE L*a*b* colorimetry.

Main Results:

• Optimized conditions include low hydrogen reduction temperature (450-500°C) and specific Al/Ba doping (0.1-0.2 wt% Al, 0.2-0.5 wt% Ba).
• Achieved pigment properties meet commercial standards.
• The process demonstrates high efficiency in KOH reuse (~99%) and Cr(VI) to Cr(III) conversion (>99%).

Conclusions:

• The proposed green process enables the production of high-quality chromic oxide green pigment.
• It offers significant advantages in resource utilization, KOH recycling, and zero hexavalent chromium emission.
• This method presents a sustainable alternative for chromic oxide green pigment manufacturing.