Development of ecofriendly high performance anti-corrosive chitosan nanocomposite material for mild steel corrosion in acid medium

Electrochemical Investigations on the Corrosion Behavior of 904L Stainless Steel in LiBr Solutions

The pitting corrosion susceptibility of 904L stainless steel in aerated LiBr solutions was investigated. The influence of various experimental variables, including electrolyte concentrations, pH, scan rate, temperatures, and constant potential has been studied using electrochemical measurements, such as cyclic potentiodynamic polarization, potentiostatic techniques, and electrochemical impedance spectroscopy (EIS). The surface morphology of 904L stainless steel was examined by scanning electron microscope (SEM). The rate of uniform corrosion and susceptibility toward pitting corrosion increases with an increase in LiBr concentrations and temperature. Increasing the pH of the solution decreases the rate of both uniform and pitting corrosion. An increase in the scan rate enhances the uniform corrosion, but suppresses the pitting corrosion. EIS diagrams displayed a depressed semicircles with the center under the real axis. Bode plots support the result that the uniform corrosion resistance of the alloy in LiBr solutions decreases with increasing Br− anion concentration. The observations suggest that this one time constant may actually be the overlap of two-time constants.

Insight into TEMPO-oxidized cellulose-based composites as electrochemical sensors for dopamine assessment

The diagnosis and treatment of many neurological and psychiatric problems depend on establishing simple, inexpensive, and comfortable electrochemical sensors for dopamine (DA) detection. Herein, 2,2,6,6 tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOC) were successfully loaded with silver nanoparticles (AgNPs) and/or graphite (Gr) and crosslinked by tannic acid, producing composites. This study describes a suitable casting procedure for the composite synthesis of TOC/AgNPs and/or Gr for the electrochemical detection of dopamine. Electrochemical impedance spectra (EIS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were employed to characterize the TOC/AgNPs/Gr composites. In addition, the direct electrochemistry of electrodes treated with the prepared composites was examined using cyclic voltammetry. The TOC/AgNPs/Gr composite-modified electrode improved electrochemical performance towards detecting dopamine compared to TOC/Gr-modified electrodes. Upon employing amperometric measurement, our electrochemical instrument has a wide linear range (0.005-250 μM), a low limit of detection (0.0005 μM) at S/N = 3, and a high sensitivity (0.963 μA μM^-1 cm^-2). Additionally, it was demonstrated that DA detection seemed to have outstanding anti-interference characteristics. The proposed electrochemical sensors meet the clinical criteria regarding reproducibility, selectivity, stability, and recovery. The straightforward electrochemical method utilized in this paper may provide a potential framework for creating dopamine quantification biosensors.