New Method to Remove Toxic Chromium from Industrial Wastewater Using Microfluidic Technology

The process begins with the fabrication of microfluidic reactors and the synthesis of nanocatalysts, followed by immobilizing the nanocatalyst onto the microreactor bed.

Researchers from the Institute of Nano Science and Technology (INST), Mohali, have developed an innovative and low-cost method to remove toxic hexavalent chromium (Cr(VI)) from industrial wastewater using sunlight as a catalyst combined with microfluidic technology. This new technique offers an efficient and sustainable solution for industries such as leather tanning and electroplating, where chromium contamination is a major concern.

Hexavalent chromium is highly toxic, and according to the World Health Organization (WHO), its concentration in drinking water should not exceed 0.05 mg/L. To address this, the INST research group led by Dr. Bhanu Prakash has designed a method that reduces Cr(VI) to its less toxic trivalent form (Cr(III)) using a process called continuous flow photoreduction. The team utilized titanium dioxide (TiO2) nanoparticles as a photocatalyst, leveraging sunlight to drive the reaction.

The novel approach integrates microfluidic technology, allowing for precise control over various parameters such as flow rate, reactor design, and catalyst phase, resulting in a remarkable 95% degradation efficiency. This was achieved by using a serpentine microreactor coated with a photocatalyst in the pure anatase phase at a flow rate of 50 µl/min. The use of microreactors also offers the advantage of reusability of the photocatalyst without the need for complex recovery processes.

The process begins with the fabrication of microfluidic reactors and the synthesis of nanocatalysts, followed by immobilizing the nanocatalyst onto the microreactor bed. The extent of chromium conversion is monitored using UV-Vis spectroscopy, ensuring high efficiency and long-term stability of the microreactor and photocatalyst.

This groundbreaking work, published in the Chemical Engineering Journal, holds significant potential for industrial applications. By increasing the throughput through parallel reactor arrays or microtexturing bulk reactor surfaces, this method could be scaled up to provide a more effective and cost-efficient solution for treating chromium-contaminated wastewater.