Removal of organic amino derivatives from wastewater by using fluorescent nitrogen-doped GQDs under visible light and fluorescence application under ultra violet light

Abstract

Photocatalysis is one of the most popular organic waste degradation treatments because it can result in the total decomposition of organic pollutants under visible light illumination. Here, we present a metal-free visible-light active catalyst for the effective decomposition of organic aromatic amino derivatives Methylene blue (MB) and Rhodamine B (RB) as model-contaminated dye molecules. Through a one-pot hydrothermal process, blue colour emissive nitrogen-doped graphene quantum dots (N-GQDs) were synthesized from urea and malic acid. The physicochemical characteristic techniques were used to analyze the surface morphology, elemental analysis, surface functional groups, absorption, emission, and band gap of prepared N-GQDs. The effective light absorption properties, transfer of electrons, separation of photoinduced charge carriers, and excellent stability with a band gap of 2.69 eV of synthesized N-GQDs have enabled the degradation of Rh B and MB up to 90 % and 86 % respectively, within 120 min of visible light irradiation. Based on extensive active species trapping experiments, a probable photocatalytic dye degradation mechanism is proposed. These N-GQDs can also be used to make fluorescent ink for imaging and security purposes.