Synthesis and characterization of scale and corrosion inhibitors with hyper-branched structure and the mechanism

Abstract

In this study, a new type of scale and corrosion inhibitors with hyper-branched structure has been developed. They have higher efficiency compared with the existing inhibitors used for industrial water treatment. The terminal amino phosphate group of hyper-branched polymers (HBPs) was synthesized through Michael addition and amidation reactions. The scale inhibition efficiency of the obtained products was determined according to their ability to prevent crystallization of calcium sulfate and calcium carbonate at the optimal application conditions. The experimental result shows that HBPs at 20 mg L⁻¹ provides a scale inhibiting efficiency for CaCO₃ and CaSO₄ up to 96.7% and 93.9%, respectively. In addition, the effect of HBPs inhibition on A3 carbon steel corrosion in 3 wt% NaCl medium was investigated by the weight loss and electrochemical measurements. The polarization measurements indicate that the prepared HBPs act as a cathodic type inhibitor. The weight loss test shows that the corrosion inhibition efficiency depends on the concentration and reaches 91.3% at 100 mg L⁻¹. The SEM and XRD analyses show that the good scale inhibition performance of HBPs is attributed to the ability to inhibit the formation of crystals and then destroy them. The study of the adsorption thermodynamics and the reaction kinetics of the corrosion process together with the SEM analysis show that the good corrosion inhibition of HBPs is derived from the carbon steel surface immersed in solution with HBPs which can induce the formation of a dense protective adsorption film layer, preventing the corrosion reaction with the surface of the carbon steel. The achieved results indicate that the prepared HBPs have a great potential for application in industrial water treatment.