Chandigarh: Researchers at a Mohali-based institute have developed a new kind of membrane using a rare chemical process that can detect toxic elements in industrial establishments or laboratories, thereby helping in preventing disasters. The mixed matrix membrane (MMM) made of two or more materials showed remarkable colour change when exposed to vapours of different amines, which are organic compounds derived from ammonia. This also opens up new avenues for practical applications of the nanomaterial.
Though ammonia or other amines are used extensively in the chemical, fertiliser and food industries as raw materials or intermediate products, according to scientists they are highly toxic and corrosive, with the potential to spread widely in the environment. They can oxidise quickly in water to form substances that are very hazardous. Direct exposure to amines can also cause severe respiratory irritation and skin irritation.
Using a ‘turn-on fluorescence process’, which is rare, a team from the Institute of Nano Science and Technology, Mohali synthesized a highly water-stable ultrathin nickel-based nanosheet with a thickness of about 4.15 nano-meters. For comparison, a normal sheet of paper is 1,00,000 nano-meters thick. According to the scientists, these nanosheets exhibited exceptional sensitivity in detecting amines and ammonia in aqueous medium through a unique fluorescence process, which is rare. The researchers used them to create an MMM that shows a colour change visible to the naked eye when exposed to ammonia and amines.
The colour change effect is different in each case, allowing the membrane to visually detect different types of vapours. These membranes are also reusable and can be easily used for real-time detection of amines. The scientists said that these nanosheets have shown better performance in various applications such as catalysis, gas separation and storage compared to other alternatives. The prescribed limit for ammonia at workplaces is 50 ppm. Concentrations above this level can cause serious and potentially fatal health problems. This makes the detection of ammonia and amines very important, whether in vapor or liquid form, for effective environmental and water monitoring, and also for preventing onsite gas leaks and disasters.
