Synthesis And Corrosion-scale Inhibition Of PDTMP

The literatures of organic phosphate salts and water-soluble polymers were reviewed. A novel corrosion-scale inhibitor of polyoxypropylene diamino tetramethylene phosphonate (PDTMP) was synthesized with amino-terminated polyether, oxymethylene and phosphorus trichloride in this paper,which structure was confirmed by Fourier transform infrared spectrometer (FTIR) and ³¹P nuclear magnetic resonance spectrum (³¹P-NMR). The inhibition of PDTMP on CaCO₃ and CaSO₄ scale was evaluated by bubble test and static antiscale method, compared with ATMP, DTPMP and PAA, and the mechanism of CaCO₃ and CaSO₄ scale inhibition was investigated by Scanning electron microscope (SEM) and X-rays diffraction (XRD). Contemporary, the effect of PDTMP on the corrosion behavior of carbon steel in 1.0mol·L^-1 HCl solution were studied and evaluated by polarization curve measurement, electrochemistry impedance spectrum (EIS), and the corrosive surface morphology of carbon steel were observed by SEM. It was found that:1. FTIR and ³¹P-NMR indicate that the synthesized compound is PDTMP surely.2. PDTMP was a geometric-coverage-type and mixed-type inhibitor, which corrosion inhibition increased with the increasing of concentration. There occurred desorption of PDTMP on carbon steel while anodic polarizing, and the entire desorption potential was about +0.14V.3. The adsorption free energyâ–³_Gads of PDTMP on the surface of carbon steel is -36.21 kJ·mol^-1, indicating that the adsorption is spontaneous. The adsorption on the surface of carbon steel obeys the Langmuir adsorption model.4. There is only one capacitive reactance arc on EIS at Ecorr, which means one time constant. But there are two time constants when the potential is -0.14V, one contain arc at high frequency area and one inductance arc at low frequency area. When the potential reached 0V, there are three time constants, one inductance arc and two contain arcs. When the polarize potential is at +0.14V, there are also three time constants, but the inductance arc disappears, and there has a bias line at low frequency area, which corresponding to diffusion impedance.5. The bubble test indicates that PDTMP has a good effect on postponing the precipitation of crystal. In the order of CaCO₃ inhibition ability at low concentration, the four scale inhibitors may be arranged as:...