Spinach to make dye-removing graphene
doi:10.1038/nindia.2015.5 Published online 15 January 2015
By using juice extracted from spinach leaves, researchers have reduced graphene oxide to graphene nanosheets, which can absorb carcinogenic industrial dyes such as methylene blue and malachite green1. The ecofriendly nanosheets could find use in removing harmful dyes from industrial effluents.
Existing chemical methods for producing graphene sheets employ harmful chemicals such as sodium borohydride, hydrazine and dimethyl hydrazine. In addition to generating toxic by-products, these methods synthesize aggregated graphene sheets, which are unsuitable for industrial applications.
The researchers reduced graphene oxide to graphene nanosheets using juice extracted from spinach leaves. This reduction process converted graphene oxide sheets to few-layer graphene nanosheets. The researchers attributed this reduction to the presence of antioxidants in spinach leaves. The reduction shortened the distance between two adjacent layers of graphene nanosheets by over half — from 0.76 nanometers to 0.36 nanometers.
The researchers found that 20 milligrams of reduced graphene sheets could completely remove methylene blue and malachite green from separate solutions that contained the dyes at a concentration of five parts per million. The graphene sheets removed the dyes under dark conditions.
In addition, the graphene sheets could mop up free radicals suggesting that they could potentially be used as industrial antioxidants, says lead author D. Suresh.