Anna University team develops novel material to treat industrial waste water under sunlight 

CHENNAI: A research team from the Crystal Growth Centre of Anna University has found an easy way to treat dyes and other organic contaminants in industrial waste water using direct sunlight.

The team led by assistant professor Shubra Singh, along with her students Durga Shankar Vavilapalli and R Janani, is working on novel materials such as brownmillerite structured calcium ferrite and zinc based chalcogenide that would act on serious water pollutants and can do wonders under direct sunlight.

Speaking to The New Indian Express, Singh said the materials synthesized by them are "visible light" photoactive and able to degrade certain toxic organic pollutants found in contaminated water under natural sunlight irradiation.

Sunlight which reaches us after being filtered by the atmosphere consists of 3-5% of ultraviolet light, 43-45% of visible light and 52-55% of infrared light. Unlike conventional UV technologies used for water treatments, the team utilizes low cost methods using visible spectrum of the natural sunlight.

"When the contaminated water is treated with the material synthesized from our lab under sunlight irradiation, it produces active species such as hydroxyl radicals which break down the molecules of the toxic organic contaminants. We are working on materials to effectively degrade various organic pollutants such as methylene blue and organic synthetic compounds such as ciprofloxacin etc. Methylene blue is commonly used as a textile dye and also as a medication to treat methemoglobinemia (a blood disorder in which too little oxygen is delivered to your cells). Ciprofloxacin is a fluoroquinolone, a common synthetic antibiotic of the quinolone drug class. This method of treatment is called photocatalysis," Singh explained. 

These materials are more efficient and cost effective as the yield of synthesis can be increased manifold. Several conventional technologies used currently in water treatments at the industrial level are either expensive or lead to secondary pollutants. The rate at which the targeted pollutants can be degraded by these materials is very high and could be used for degradation of highly concentrated pollutants in water as well.

Singh said researchers have also worked on recycling the photocatalyst to use them in repeated cycles. "Some of these materials are multifunctional and can also be used for hydrogen production. The team has published their research work in several reputed peer-reviewed journals like Scientific Reports, Nature Research, Renewable Energy and filed several patents," she said.

Now, the team is collaborating with IIT Madras researchers. A proposal has been submitted to the Department of Science and Technology (DST) to test these novel materials on antibiotic residues found in freshwater sources near the Pallikaranai marshland.