Environmental-friendly curcumin based fluorescent polymer for calcium sulfate scale inhibition

A green fluorescent labeled scale inhibitor, curcumin-poly (malic acid) (Cur-PMA) was synthesized from curcumin and malic acid (MA). The structure of Cur-PMA was characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance ( 1 H NMR) and gel permeation chromatography (GPC) analysis. Thermogravimetric analysis (TGA) and fluorescence spectroscopy revealed that Cur-PMA had good thermal stability and was expected to enable on-line detection. The static scale inhibition experiment showed that the scale inhibition rate of Cur-PMA on calcium sulfate can reach 100% with 10 mg/L. In addition, the impacts of pH and environmental temperature on calcium sulfate scale were discussed. The influence on formation of CaSO 4 was evaluated with combination of scanning electronic microscopy (SEM), X-ray powder diffraction (XRD) and Molecular dynamics (MD) simulation. It was shown that the scale inhibition ability of Cur-PMA molecules was mainly through adsorption on the surface of growing crystals to inhibit the growth of these crystal planes. • An efficient green fluorescent scale inhibitor was synthesized. • Characterizations of FT-IR and 1 H NMR methods. • The fluorescence intensity has a linear relationship with the dose of scale inhibitor. • The inhibition efficiency to calcium sulfate scale.