CSMCRI researchers develop photocatalyst to completely degrade industrial dyes

Researchers from the Central Salt & Marine Chemicals Research Institute (CSMCRI), Bhavanagar, Gujarat have developed photocatalyst that can completely degrade three industrial dyes in the presence of sunlight. This photocatalyst is able to completely degrade three industrial dyes — methyl orange, methylene blue and reactive black-5. Key Facts The photocatalyst was developed using titanium dioxide doped with red

seaweed polymer carrageenan (a substance extracted from purple and red seaweeds). Conventionally, titanium dioxide was used for photocatalytic degradation of industrial dyes, but it took long time to degrade dyes. So the researchers from CSMCRI doped titanium dioxide nanoparticles with sulphur and carbon by treating it with carrageenan. The nanocomposite was found to behave as an excellent photocatalyst that degraded the industrial dyes quickly in a single-step process. The photocatalyst was found to degrade the dyes when exposed to direct sunlight. When a solar concentrator is used, the intensity of the degradation process of dyes also increased. Significance: The nanocomposite photocatalyst is thermally stable. It can be reused up to 6 times with the degradation efficiency remaining at over 97%. It can safely and completely treat harmful dyes in an eco-friendly and cost-effective manner. Problems Annually, more than 500 tonnes of non-degradable textile colour wastes without adequate treatments are being disposed of in natural streams. Presently, despite having stringent environmental regulations a comprehensive method of treating industrial dye is not available. The methods which are available do not completely break down the dye molecules to non-toxic constituents and are also expensive.