Fluorescent and antibacterial sulfur quantum dots as calcium sulfate scale inhibitor

Over the past few years, nanomaterials have been gradually developed as scale inhibitors. In this work, an environmentally friendly and antibacterial sulfur quantum dot scale inhibitor (CMC-SQDs) was synthesized using carboxymethyl cellulose (CMC) as a passivator and stabilizer. The calcium sulfate scale inhibition performance of CMC-SQDs under different external environments (i.e., scale inhibitor concentration, retention temperature, pH) was investigated based on the static scale inhibition method. In addition, the synthesized CMC-SQDs were characterized by transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FT-IR), x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The effects of CMC-SQDs on CaSO₄ scale formation were evaluated by scanning electron microscopy (SEM) and x-ray powder diffraction (XRD). The CMC-SQDs prepared in this work have stable fluorescence, good water solubility, and temperature resistance. The scale inhibition rate of CMC-SQDs for CaSO₄ reached 100 % when the concentration was only 1.2 mg/L, which was significantly higher than that of the same type of scale inhibitors. Meanwhile, the antibacterial test showed that the inhibition rate was maintained above 90 % at 5.0 mg/L of sulfur quantum dots.