Effect of degree of deprotonation of maleic anhydride‐allyl polyethoxy carboxylic acid copolymer on calcium scale

Abstract

A hydrophilic copolymer (MA‐APEA) containing carboxylic acid group and ethylene oxide group is synthesized from maleic anhydride (MA) and allyloxy polyethoxy carboxylic acid (APEA) in free radical polymerization and its structure is characterized using FT‐IR, 1H nuclear magnetic resonance spectrometer and gel permeation chromatographic techniques. Seven polymer solutions with different degrees of deprotonation are prepared by adding caustic solution to the polymer solution. Effects of the degree of deprotonation of the polymer on curbing calcium scale and the corrosion inhibition of low carbon steel are studied. Influences of the operating conditions on inhibition against CaCO3 scale by the polymer with different degrees of deprotonation are also investigated. Effects of the degree of deprotonation on CaCO3 deposits/precipitate are analyzed using scanning electronic microscope and X‐ray diffraction. The results show that different degrees of deprotonation of the polymer have different influences on different calcium scale and corrosion inhibition of low carbon steel. The performance of the polymer to withstand high alkalinity and high hardness and high temperature decreases with increase in the degree of deprotonation. The change in the degree of deprotonation influences the conversion of aragonite and vaterite to calcite, and hardly impacts the crystal morphology of CaCO3 crystals. MA‐APEA has proven to be an excellent calcium scale inhibitor.

A novel and efficient CaCO3 scale inhibitor in high‐temperature and high‐salinity geothermal systems: A deprotonated quadripolymer

“…The peaks included the following: 1.19, 1.46, and 1.89 ppm (CH 2 , protons in methylene), 2.10–2.70 ppm (CH, protons in methine), 3.72–3.81 ppm (OH, protons in oxhydryl groups), and 7.87 ppm (CH, protons on benzene). In addition, there are no peaks at 5.30–5.70 ppm, indicating that CC disappeared completely 29 . Note that the active proton in COOH is easily exchanged with the D 2 O proton, so its characteristic peak is not observed.…”

“…At this point, D‐CAAS cannot chelate excess calcium. (2) Deprotonation significantly enhanced electrostatic adsorption on the surface of D‐CAAS and CaCO 3 , indirectly connected multiple crystal nuclei, and reunited them, which is called the “bridging effect” 29 . This accelerates the precipitation of CaCO 3 and leads to a decrease in scale inhibition efficiency.…”

Synthesis of a New Type of 2-Phosphonobutane-1,2,4-tricarboxylic-Acid-Modified Terpolymer Scale Inhibitor and Its Application in the Oil Field

“…Figure c shows that the higher the concentration of AA–APES–HPAY, the more obvious the change of the crystal surface morphology. The crystal appears with elliptical and sheet structures . The calcium scale of these two structures is light and has no edge angle.…”

“…The crystal appears with elliptical and sheet structures. 7 The calcium scale of these two structures is light and has no edge angle. Meanwhile, the texture is soft, and the adhesion ability is poor.…”

“…At present, many chemical scale inhibitors have been applied to the prevention and control of oilfield scale, but the scale inhibition efficiency is low and the cost is high. Commercial scale inhibitors for carbonate and sulfate scaling are usually polymers, such as poly­(acrylic acid), polymaleic anhydride, polyphosphate, etc. − Polyphosphonic acid scale inhibitors play a key role in the performance of oilfield scale inhibition, and they are also the most widely used . However, most of the phosphonic acid scale inhibitors currently on the market, such as amino trimethylene phosphonic acid (ATMP) and ethylene diamine tetramethylene phosphonic acid (EDTMPA), have poor compatibility with calcium ions and will cause complex precipitation .…”