Sunlight-Powered Method to Remove Toxic Chromium

Researchers at the Institute of Nano Science and Technology (INST) have developed an affordable method to remove toxic chromium from industrial wastewater.

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• Use of Sunlight: Sunlight is used as a catalyst to convert the toxic Cr(VI) into the less harmful Cr(III).
• Microfluidic Technology: The method uses a continuous flow photoreduction process with the help of microfluidic reactors and TiO2 nanoparticles.

About Chromium

• It is a steely-grey, shiny, hard, and brittle transition metal.
• Unique feature: Chromium is known for its strong resistance to corrosion and its hardness.
• Applications
  •  It is used to produce alloys.
    • Used in production of stainless steel.
      • Its plating is used to give polished mirror finish to steel. 
    • Its compound is used as an  industrial catalyst and pigments.  
    • Chromium is used to tan  leather. 

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Chromium Toxicity Overview

• Hexavalent Chromium Risks: Hexavalent chromium (Cr(VI)) is very toxic and can cause serious health problems such as lung cancer, allergies, and eczema. 
• WHO Guidelines
  • Hexavalent chromium: The World Health Organization (WHO) recommends that Cr(VI) in drinking water should be no more than 0.05 mg/L.
  • Trivalent Chromium: For trivalent chromium (Cr(III)), the limit is 5 mg/L.

Challenges in Removing Chromium

• High soluble: Removing Cr(VI) from wastewater is a challenging task because it is highly soluble and resistant to traditional treatment methods.
• Costly and inefficient methods: Existing techniques like ion exchange, adsorption, and chemical reduction are costly and often inefficient in removing Cr(VI).
• Harmful byproduct: Additionally, these methods may produce hazardous byproducts.

Advantages of the New Method

• Cost-Effective: The process is affordable and uses renewable energy.
• Environmentally Friendly: The method utilizes sunlight as a catalyst which makes it a sustainable and cost-effective approach.
• High Efficiency
  • 95% Degradation: The researchers achieved a high degradation efficiency of 95% using a serpentine microreactor at a flow rate of 50 µl/min.
• Reusability: The photocatalyst can be reused without the need for recovery agents or complicated processes.

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