Polyaniline has a wide application in the field of corrosion protection, the poor solubility of polyaniline limited its application as a corrosion inhibitor. Water-soluble carboxymethyl cellulose -polyaniline composites was synthesized by chemical oxidation polymerization in a mild way without other inorganic or organic acids added. Corrosion inhibition performance of composites was evaluated for Q235 steel corrosion in 1 M HCl corrosive solution using weight loss and electrochemical measurements at various concentrations. The results show that carboxymethyl cellulose -polyaniline composites exhibit good inhibition properties and the remarkable increase in inhibition efficiency, i.e., 94.24% is achieved while the maximum concentration of the experiment is 1000 ppm. The composites in corrosive solution suppress the cathodic hydrogen evolution reactions and anodic metal dissolution of the substrate. Adsorption of the inhibitor on the steel surface follows a Langmuir adsorption isotherm.
Novel nitrogen and sulfur co-doped carbon dots (N,S-CDs) were synthesized via a hydrothermal procedure using citric acid (CA) and thiourea (TU) as precursors, and the corresponding corrosion protection performance was first investigated for Q235 carbon steel in 1 M HCl solution. Experimental results indicated that N,S-CDs as mixed-type corrosion inhibitors could effectively prevent Q235 carbon steel from corrosion in 1 M HCl solution, and the corrosion inhibition efficiency was improved with the increase in N,S-CD concentration. The maximum value was achieved at 400 ppm of N,S-CDs at 25 °C, which was approximately 96.6%, 94.6% and 90.55%, according to the potentiodynamic polarization curves, EIS results and weight loss measurement, respectively. Additionally, with the temperature ranging from 25 to 55 °C, the inhibition efficiency obtained from the weight loss measurement was enhanced from 90.55% to 94.04%. Such superior inhibition effect was assigned to the physisorption and chemisorption of N,S-CDs on the Q235 carbon steel surface, which was also be confirmed by XPS analysis. The adsorption of N,S-CDs onto a steel substrate conformed to the Langmuir adsorption isotherm.
In this work, a water-soluble host–guest complex containing carboxymethylated beta-cyclodextrin (CM-β-CD) and an aniline trimer (AT) was synthesized. The application of AT–CM-β-CD as an inhibitor for alleviating the corrosion of Q235 carbon steel in 1 M HCl solution was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Results showed that the inhibition efficiency was significantly increased in the presence of AT–CM-β-CD, and the inhibition efficiency was up to 99.2% when the concentration of AT–CM-β-CD was 250 mg L−1. Field emission scanning electron microscopy (SEM) and laser scanning confocal microscopy (LSCM) confirmed that the corrosion inhibitor had excellent corrosion inhibition effects due to the formation of an adsorption film on the surface of Q235 carbon steel. According to the data extracted from the Langmuir adsorption model, AT–CM-β-CD absorption involves both physisorption and chemisorption.
Jingbao Wang,Jing Jing,Li Feng,Hailin Zhu,Zhiyong Hu,Xuemei Ma
The corrosion inhibition behavior and adsorption mechanism of three novel synthetic surfactants in 1 M HCl solution on carbon steel were investigated. The PP results confirmed that all the synthetic surfactants behave as mixed-type inhibitors, while the EIS results validated the existence of a protective layer by the adsorption of inhibitor molecules on the carbon surface. T 3 was observed to offer the highest inhibition efficiency ( η w , 96.28%) at 1 mM by the static weight loss measurements due to two different hydrophobic chains which form a more compact film with the crosswise arrangement. SEM/EDS and XPS results revealed the formation of the surfactants film on the carbon steel surface. Molecular dynamics simulation (MD) was further executed to determine the adsorption mechanism in molecular level insights. In addition, a linear correlation between surface activity ( γ ) and corrosion inhibition efficiency ( η w ) was verified. The adsorption of the prepared surfactants followed the Freundlich isotherm at different concentration ranges. Moreover, the bilayer/multilayer adsorption mechanism was also proposed and confirmed by experimental, adsorption isotherm studies and MD. Hence, both MD simulations and experimental results revealed the analogous inhibition with the order follows: T 3 > T 2 > T 1 .
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