Corrosion inhibition performance of composite based on chitosan derivative

The shortage of water resources has resulted in municipal wastewater(MWW) becoming the main source of industrial cooling water replenishment. However, MWW causes severe erosion in carbon steel water pipelines, and the most widely used phosphorus-containing corrosion inhibitor currently available, 2-hydroxyphosphonocarboxylic acid (HPAA), only shows effective inhibitory effects at high doses. In this work, a natural polymer, N-carboxylated chitosan (NCC), was developed via a pollution-free method, and the resulting compound was formulated as a water treatment corrosion inhibitor. This compound was composited with NCC, HPAA, gluconic acid sodium (GA), and ZnSO4, and the resulting compound was abbreviated as NHGZ. This process greatly reduced the use of phosphorus-containing compounds. The performances of NCC and NHGZ were then evaluated by electrochemical and weight-loss studies. Electrochemical test results demonstrated that NCC is a cathodic corrosion inhibitor, whereas NHGZ is a mixed corrosion inhibitor. The weight-loss studies showed that the corrosion rate of NHGZ in MWW at 40 degrees C was only 0.0254 mm/y, which was lower than that of the uninhibited sample of 0.9268 mm/y. This effect was attributed to the ability of the NHGZ to molecularly adsorb onto and form a stable protective inhibitor film on the surface of carbon steel. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and theoretical adsorption simulations were employed to explain the possible corrosion inhibition mechanism of NHGZ. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The research found that NCC acts as a cathodic corrosion inhibitor and NHGZ acts as a mixed corrosion inhibitor. NHGZ exhibits a corrosion rate of only 0.0254 mm/y in MWW at 40 degrees C, lower than the uninhibited sample of 0.9268 mm/y. NHGZ is able to molecularly adsorb onto the surface of carbon steel and form a stable protective inhibitor film, thereby inhibiting corrosion effectively.