Indian Scientists develop an eco-friendly smart screen from Groundnut shell waste

 Indian Scientists develop an eco-friendly smart screen from Groundnut shell waste

Groundnut shell is a waste which either is burnt in open or piled up after taking out groundnuts from it. In some places, it is converted into pellet or briquettes and burnt in a Kiln or boiler. Indian scientists have developed another eco-friendly smart screen from groundnut shells that would not only help in preserving privacy but also in energy conservation by controlling light and heat passing through it and reduce air conditioning load.

The technique is simple but unique—scientists from the Centre for Nano and Soft Matter Sciences (CENS) Banglore developed a cellulose-based smart screen from the discarded groundnut shells.

Indian scientists have developed an eco-friendly smart screen from groundnut shells that could help not only in preserving privacy but also in energy conservation by controlling light and heat passing through it and reducing air conditioning load.

Though in principle, the device could be developed from any cellulose or agricultural waste, due to certain properties of groundnut waste, the smart screen developed from groundnut, waste has been found to be most efficient.

The scientists of CENS led by Professor S Krishna Prasad developed the smart screen, in which liquid crystal molecules were confined in a polymer matrix, prepared from discarded groundnut shells.

The refractive index of the liquid crystal molecules along a particular direction were altered by the application of an electric field. In the absence of the electric field, there was a mismatch between refractive indices between those of the polymer and the liquid crystal, leading to the scattering of light.

Upon application of a few volts of an electric field, the liquid crystal molecules underwent a direction change resulting in the matching of refractive indices, and the device became transparent almost instantaneously.

When the field was turned off, the system quickly recovered the scattering state. This reversible change between the two states available at the flip of a switch occurred over thousands of cycles, with essentially no change in contrast or switching speed.

The device they developed, described in a recent issue of Applied Physics Letters employed the same principle that causes fog on winter mornings. This happens only when the water droplets are of the right size, and it can co-exist along with air. The incoming light sees these two as materials of different refractive indices and thus gets scattered, giving a foggy appearance. Similarly, the polymer and the liquid crystal should co-exist in the right size to create the required optical properties for the smart screen.

Ms Pragnya and Dr Srividhya, the students who worked on the device, emphasize that the protocol for the CNC preparation plays a key role in controlling the device contrast with the IIT Roorkee material outperforming the CNC available from commercial sources.

Apart from the original intention of targeted privacy creation, the device can be employed for a whole range of possible applications, especially in the energy conservation by controlling the amount and window of infrared light that is permitted to pass. For example, while a window having this technology would remain transparent to the entire visible region, undesirable levels of heat radiation could be significantly reduced, keeping the enclosure cool.

Groundnut Shell waste in India

Groundnut shells account for approximately 20% of the dried peanut pod by weight, meaning there is a significant amount of shell residual left after groundnut processing. Increased groundnut production leads to the accumulation of these groundnut shells which is not utilized, thus either burnt or buried. As Groundnut shells are rich in many functional compounds and composed of cellulose, hemicellulose and lignin, it can be utilized in multiple ways. This review highlights potential applications of groundnut shells for commercial and industrial purposes. Groundnut shells can be converted in various bio-products such as biodiesel, bioethanol, nano-sheet and also has applications in enzyme and hydrogen production, dye and heavy metal degradation etc. An efficient management strategy is required to convert this otherwise considered waste into valuable bio-products to achieve zero waste production system.

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