Indian researchers find a way to remove toxic chromium from wastewater

Indian researchers from the Institute of Nano Science and Technology (INST) in Mohali, led by Dr. Bhanu Prakash, have developed a new technique to tackle chromium contamination in wastewater. This technique uses sunlight as a catalyst in combination with microfluidic technology to convert toxic hexavalent chromium [Cr(VI)] in the less harmful trivalent chromium [Cr(III)]This development has important implications for industries such as tanning and electroplating, which are known for their high chromium discharge.

WHO standards and traditional methods

The World Health Organization (WHO) has set strict limits for chromium in drinking water: 0.05 mg/L for hexavalent chromium and 5 mg/L for trivalent chromium. Reducing hexavalent chromium is essential because of its high toxicity. Conventional methods for chromium removal, such as ion exchange, adsorption and chemical reduction, are often expensive and often inefficient.

Details of the new method

Dr. Bhanu Prakash’s team at INST has introduced a continuous photoreduction process using TiO2 nanoparticles and sunlight. They validated this method with a smartphone-based colorimetric technique to monitor chromium reduction in wastewater. The use of microfluidic technology allows precise control over flow rate and reactor dimensions, improving reduction efficiency.

Benefits and future potential

A major advantage of this method is its cost-effectiveness and dependence on renewable energy. Microfluidic reactors in this process allow the photocatalyst to be reused without complex recovery procedures. The researchers achieved a 95% reduction in chromium levels using a serpentine microreactor with an anatase phase photocatalyst by optimizing parameters such as reactor design and flow rate.

This research, published in the Chemical Engineering Journal, shows the potential for upscaling. By setting up parallel microfluidic reactors or improving reactor surfaces, the researchers aim to improve the efficiency and capacity of this process, making it a promising solution for large-scale wastewater treatment.