Detection of Cu2+, Degradation of Acid Brown and Removing Cd2+ from the Water by High Photoluminescence Carbon Dots Synthesized from Milk

In this experimental work, nitrogen-doped carbon quantum dots were successfully synthesized with hydrothermal of the milk. The product was composed of a powder and a stable colloid. The structure of the product was examined by XRD, EDS and FT-IR analysis. Also the particle size of the product was investigated by SEM and TEM images and the results showed the product is mainly composed of the particles with less than 5 nm in diameter. The photoluminescence intensity of the product was obtained by PL analysis and it was found the product has high photoluminescence intensity that can be improved by surface modification with N-Methyl-2-pyrrolidone. Due to high photoluminescence intensity of the obtained quantum dots they were used as a sensor to detection of Cu2+ and it was observed they can detect this ion in the aqueous medium for 0-80 uM concentration range. Also it was found by surface modification of carbon dots with N-Methyl- 2-pyrrolidone, the detection sensitivity is improved. The optical properties of the product were studied by UV-Vis spectroscopy. The results showed the product can absorb light in the visible range and by increasing the Cu2+ concentration the band gap is increased that is mainly due to decrease of electron trap centers. The photocatalytic activity of the product was examined by degradation of Acid brown and it was found the product can decompose the dye after 30 min of irradiation. Due to huge surface of the product, it was served to adsorb Cd2+ ions from aqueous medium. The results showed the synthesized quantum dots can adsorb the ions more than 69% from the water. It was concluded that due to high photocatalytic and surface adsorption activity of the product it can be used for water purification potentially to degrade of organic pollution and removing heavy metal ions from the water.