Green synthesis of high photoluminescence nitrogen-doped carbon quantum dots from grass via a simple hydrothermal method for removing organic and inorganic water pollutions

In this work, highly photoluminescence nitrogen-doped carbon quantum dots (N-CQD) were synthesized via a simple hydrothermal method from a very low cost and green material. Different analysis were used to approve synthesis of the quantum dots such as X-ray diffraction pattern (XRD), energy dispersive X-ray analysis (EDAX) and Fourier-transform infrared spectroscopy (FT-IR). The morphology of the product was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. In addition, the surface topography was studied by atomic force microscopy (AFM) and it was found the product has tiny and uniform particles. The photoluminescence (PL) analysis was served to study the photoluminescence intensity and it was found the product has high photoluminescence intensity. To investigate the photocatalytic activity of the product, five dyes namely Acid Blue, Acid Red, Eosin Y, Eriochrome Black T, Methyl orange and Methylene blue were decomposed under radiation. Surface activity of the product was evaluated by adsorption Cd²⁺ and Pb²⁺ from the water and the results showed the carbon dots can remove these two heavy metal ions from the water with 37% and 75%, respectively.