Effects of Al2O3 nanoparticles on the formation of inorganic scale on heat exchange surface with and without scale inhibitor

The scale inhibition and mechanism of the scale inhibitor PBTCA (2-phosphonobutane-1,2,4-tricarboxylic acid) on CaCO 3 in a scale-forming solution and an Al 2 O 3 nanofluid were investigated by solution scale inhibition, surface scale inhibition, electrical conductivity, scanning electron microscopy, X-ray diffraction, and diffuse reflection Fourier transform infrared spectroscopy. The results showed that PBTCA had good solution scale inhibition performance and surface scale inhibition performance on heat exchange surface in scale-forming solution. In an Al 2 O 3 nanofluid, the solution scale inhibition performance of PBTCA decreased with an increase in nanoparticle concentration. However, the surface scale inhibition performance of PBTCA first decreased and then increased with an increase in Al 2 O 3 nanoparticle concentration, and the surface scale inhibition performance was obviously higher than the solution scale inhibition performance. Al 2 O 3 nanoparticles significantly shortened the induction period of CaCO 3 nucleation in the scale-forming solution containing PBTCA, weakening the solubilization of PBTCA on CaCO 3 and decreasing the solution scale inhibition of PBTCA, whereas Al 2 O 3 nanoparticles promoted the formation of aragonite and exhibited certain surface scale inhibition performances.