Sustainable production of graphene quantum dots from rice husk for photo-degradation of organochlorine pesticides Nachhaltige Herstellung von Graphen-Quantenpunkten aus Reishülsen für den Fotoabbau von Organochlorpestiziden

The controlled synthesis of two-dimensional nanocrystals of graphene particles instead of amorphous carbon quantum dots is highly challenging and requires tremendous efforts to optimize the reaction conditions. It has been observed that as a significant bio-compatible zero-dimensional material, graphene quantum dots are considered as a novel material for opto-electronics, energy, biological and environmental applications. However, very few are known about their utilization in photocatalytic degradation of pesticides, especially organochlorine pesticides which are resistant to removal by conventional wastewater treatment methods. In this work, graphene quantum dots were produced from rice husk at relatively low temperatures, resulting in an average particle size of 3.3 nm. The high resolution transmission electron microscopy clearly showed the formation of spherical quantum dots having lattice fringes and the selected area electron diffraction pattern showed the crystallinity of the graphene quantum dots. A study of photodegradation of three highly toxic organochlorine pesticides namely, dichlorodiphenyl trichloro ethane, cypermethrin and fenvalerate were carried out using as-synthesized graphene quantum dots from rice husk. Interestingly, all these pesticides were found to be degraded around 60 % to 70 % under visible light conditions. It confirmed that synthesized graphene quantum dots from rice husk can act as prominent photocatalyst for the degradation of pesticides and other pollutants.