Researchers from the Institute of Nano Science and Technology (INST), Mohali, have developed a low-cost method to remove toxic hexavalent chromium from industrial wastewater, such as from leather tanning and electroplating. This innovative technique combines sunlight as a catalyst with microfluidic technology.
Hexavalent chromium is highly toxic, with WHO guidelines limiting its concentration in drinking water to 0.05 mg/L. To meet these standards, it is essential to convert hexavalent chromium (Cr(VI)) to the less harmful trivalent chromium (Cr(III)).
Traditional methods like ion exchange, adsorption, and chemical reduction are often expensive and less efficient. In contrast, Dr. Bhanu Prakash’s research group at INST has employed a continuous flow photo-reduction process using TiO2 nanoparticles. They validated this method with a smartphone-based colorimetric technique.
The process is both cost-effective and sustainable, utilizing renewable energy. It allows precise control over reduction efficiency by adjusting microfluidic parameters such as flow rate, reactor dimensions, and architecture. Notably, micro-reactors enable the reuse of photocatalysts without requiring recovery agents.
The team achieved a 95 per cent degradation efficiency using a serpentine microreactor coated with TiO2 in its pure anatase phase, operating at a flow rate of 50 µl/min. The process involves fabricating microfluidic reactors, synthesizing and immobilizing nanocatalysts, and monitoring efficiency with UV-Vis spectroscopy. The researchers also assessed the reactor’s long-term stability through multiple cycles.
Published in the Chemical Engineering Journal, this breakthrough offers significant potential for industrial applications. By setting up microfluidic reactors in parallel or texturing reactor surfaces, the approach could be scaled up to enhance throughput and efficiency.
