# Comparative Study of Corrosion Inhibition Properties of Q345 Steel by Chitosan MOF and Chitosan Schiff Base

## TL;DR

This study compares two eco-friendly inhibitors for protecting steel in corrosive environments, finding one significantly more effective due to its chemical structure.

## Contribution

A novel molecular design strategy for green corrosion inhibitors combining metal-organic coordination chemistry and biopolymer modification.

## Key findings

- Schiff–CS@Cu reduced corrosion rate to 1.67 g/(m2·h) with 93.56% efficiency at 100 mg/L.
- Schiff–CS@Cu's pyridine–Cu2+ chelation formed a dense barrier against Cl−/H+ penetration.
- Both inhibitors achieved optimal performance at 100 mg/L concentration.

## Abstract

This study synthesized two eco-friendly inhibitors—a chitosan–copper metal–organic framework (CS@Cu MOF) and chitosan–Schiff base–Cu complex (Schiff–CS@Cu)—for Q345 steel protection in 3.5% NaCl/1M HCl. Electrochemical and weight loss analyses demonstrated exceptional corrosion inhibition: untreated specimens showed a 25.889 g/(m2·h) corrosion rate, while 100 mg/L of CS@Cu MOF and Schiff–CS@Cu reduced rates to 2.50 g/(m2·h) (90.34% efficiency) and 1.67 g/(m2·h) (93.56%), respectively. Schiff–CS@Cu’s superiority stemmed from its pyridine–Cu2+ chelation forming a dense coordination barrier that impeded Cl−/H+ penetration, whereas CS@Cu MOF relied on physical adsorption and micro-galvanic interactions. Surface characterization revealed that Schiff–CS@Cu suppressed pitting nucleation through chemical coordination, contrasting with CS@Cu MOF’s porous film delaying uniform corrosion. Both inhibitors achieved optimal performance at 100 mg/L concentration. This work establishes a molecular design strategy for green inhibitors, combining metal–organic coordination chemistry with biopolymer modification, offering practical solutions for marine infrastructure and acid-processing equipment protection.