News Excerpt
Researchers from IIT Bombay have successfully developed a carbon-based nanostructure which can simultaneously remove heavy metals such as arsenic, chromium, cadmium and mercury from wastewater with very high efficiency.

Pre-Connect
About
•    Heavy metal refers to any metallic chemical element with high density and is toxic or poisonous at low concentrations. For eg. mercury (Hg), cadmium (Cd), arsenic etc.
•    Objective of the test was to find a structure which can adsorb heavy metals found in industrial effluent having pH between the range of (pH 2-13).
•    The team developed a Marigold like carbon-based nanostructure which is obtained through a single-step process of chemical vapour deposition followed by removing the silica template.
•    This nanostructure showed 80-90% adsorption efficiency for all the four heavy metals studied.

Mechanism
    Majority of adsorption takes place as soon as water contaminated with heavy metal comes in the contact with the nanostructure.
    As the heavy metal chemically react and bind to the surface of the nanostructure it doesn’t leach.
    Further, these heavy metals can be recovered by treating nanostructure with a mild acid.  

Analytica
Advantage of Nanostructures
    Its hydrophilic or water-loving nature provides for extensive and rapid interaction between the heavy metal-containing water and the carbon nanostructure.
    It is based on the gravity-driven purification and hence no electricity is required.
    It can be recycled and reused multiple times, so it’s cost-effective.
    It has high adsorption as surface area of nanostructure is easily accessible for heavy metals, unlike activated carbon.

Significance
    Majority of the rural population in India drink water which is contaminated by heavy metals like fluoride, arsenic and nitrate.
    According to the Central Water Commission, 42 rivers in India are contaminated by heavy metals toxins beyond the permissible limit. West Bengal is worst affected with over 39 per cent of the total affected population in India.

Nano-Structures
    Their size is in the range between 1 nm and 100 nm.
    Synthetic and nature and can be engineered
    Different forms include nano-tubes, spheres and surfaces.
    Carbon Nanostructures have wide range of application in medical and biotech field such as bio sensors, bio simulators, tissue implantation etc.  

PEPPER IT WITH
Carbon Nanotubes, Nanomedicine, Quantum Dots, Nanoelectronics