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Hexavalent Chromium Remediation Using Nature’s Own
March 27, 2019

Hexavalent Chromium Remediation Using Nature’s Own

  • Indumathi M. Nambi Department of Civil Engineering

Science is always in search of techniques that help us reduce energy consumption while enabling multi-purpose use and economical methods to treat the toxicity. One such toxic element that is widely used is Chromium. Hexavalent chromium [Cr (VI)] is a metal which is widely used in the textile and tanning industry. It is classified as a human carcinogen and can cause respiratory, skin, kidney, liver and gastric illnesses. A team of scientists from IIT Madras has come up with an electrolytic cell that can treat Cr(VI) using natural cow urine, with no other input of external energy.

The electrolytic cell utilizes the inherent chemical energy present in the dual-waste streams-Cr(VI) and urea, to sustain a self-oxidation-reduction reaction. Thus, it is capable of reducing Cr(VI) to a less toxic Cr(III), while oxidising urea without consuming any external energy. By using cow’s urine which is a natural and abundant source of urea, the scientists were able to achieve 98% detoxification in just 45 minutes! Alternatively, human urine which is a major waste discharge from dialysis and sewage, if utilized, could help us to sustainably manage two major waste streams in one process.
To prevent the electrolytes from mixing, the cell has a clever design of three chambers: a cow urine chamber, a buffer chamber and a Cr(VI) chamber. With proper positioning of ion exchange membranes, the team of scientists were able to maintain two different pH environments within the cell, while maximizing reaction rates.