Versatile Coffee Carbon Dots as Lead (ii) and Copper (ii) ion Fluorescence Detectors and Copper Corrosion Inhibitor

Abstract

A simple and green tandem hydrothermal and pyrolysis method was developed for the synthesis of blue fluorescence carbon dots from coffee green bean powder and urea as raw materials. The carbon dots were characterized by ultraviolet visible spectrophotometer, Fourier-transform infrared spectroscopy and ocean optics spectrophotometer. The carbon dots had a bright blue emission centered at 505 nm under UV light with the excitation wavelength at 360 nm. The carbon dots also showed a quenching effect with lead (ii) ions and copper (ii) ions. Furthermore, a method for copper (ii) and lead (ii) ion detection in aqueous solution was developed with acceptable linearity of 97.26% and 99.41% respectively and selectivity to some common ions. The carbon dots also demonstrated the ability to act as copper corrosion inhibitors in 1% sodium chloride solution showing an inhibition efficiency of 77% at 1000 ppm. It is worth noting that the synthesized fluorescent carbon dots are eco-friendly and inexpensive. They could find application in chemical sensing and copper corrosion inhibition in salt environments.