Multidimensional insights into the corrosion inhibition of 3,3-dithiodipropionic acid on Q235 steel in H2SO4 medium: A combined experimental and in silico investigation.

3,3-Dithiodipropionic acid (DDA) as a potential corrosion inhibitor for Q235 steel in 0.5 M H2SO4 solution was examined. A variety of research approaches including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), scanning electron microscopy (SEM), atomic force microscopy (AFM), and computational techniques were employed. The toxicity and solubility of DAA were reasonably assessed. Its inhibition efficiency can reach approximately 93% when the optimal concentration is 5 mM. The results of PDP curves manifest that DDA is a mixed type corrosion inhibitor. EIS data indicate that the charge transfer resistance increases with increasing concentration of DDA. Gibbs free energy obtained from the Langmuir isotherm model suggests that DDA molecules hinder the acid attack mainly by chemisorption. Surface topography analysis strongly confirmed the electrochemical findings. Moreover, the simulation results based on density functional theory (DFT) calculation and molecular dynamics (MD) simulations supported the successful interfacial adsorption of DDA on Fe(1 1 0) surface.

Synergistic effect of potassium iodide and sodium dodecyl sulfonate on the corrosion inhibition of carbon steel in HCl medium: a combined experimental and theoretical investigation.

Carbon steel is an important industrial material, but it usually suffers from serious corrosion in the service environment. Using corrosion inhibitors is an effective approach to mitigate corrosion. The synergistic inhibition behavior of sodium dodecyl sulfonate (SDS) and potassium iodide (KI) on carbon steel corrosion in hydrochloric acid medium was investigated by electrochemical test, surface morphology analysis, and molecular simulation approaches. Results show that the corrosion inhibition performance is significantly enhanced after the two substances are compounded, and the inhibition efficiency can reach approximately 96% at small doses. The Tafel polarization curves suggest that the mixtures can be classified as anodic corrosion inhibitors. Impedance tests indicate that the inhibitor molecules are adsorbed on the steel surface, resulting in an increase of charge transfer resistance but a decrease of electric double layer capacitance. The adsorption process follows the Langmuir adsorption isotherm. Molecular simulation calculations further reveal the active sites of SDS and the stabilizing effect that I- plays in the inhibition process. The present research offers an economic, environmentally friendly and efficient measure of corrosion control, and provides theoretical guidance for the efficient use of carbon steels and the development of novel corrosion inhibitors.

Multidimensional insights involving electrochemical and in silico investigation into the corrosion inhibition of newly synthesized pyrazolotriazole derivatives on carbon steel in a HCl solution.

Herein, the anti-corrosion of carbon steel in 1 M HCl by two newly synthesized pyrazolotriazole derivatives, namely, 6-methyl-1H-pyrazolo[5,1-c][1,2,4]triazole-7-carbonitrile (CPT) and 1-acetyl-6-methyl-1H-pyrazolo[5,1-c][1,2,4]triazole-7-carbothioamide (MPT), was studied using electrochemical, density functional theory (DFT), and molecular dynamics (MD) simulation techniques. The experimental results showed that the concentrations of inhibitors had a significant influence on their inhibition efficiencies. Potentiodynamic polarization curves indicated that the two pyrazolotriazoles were mixed-type inhibitors. DFT calculations were employed to explore the molecular activity, and MD simulations were performed to obtain the interaction energy between the inhibitor molecules and the iron surface. The findings obtained using the theoretical calculation techniques were consistent with those obtained via experiments.

Optimum Water Quality Monitoring Network Design for Bidirectional River Systems.

Affected by regular tides, bidirectional water flows play a crucial role in surface river systems. Using optimization theory to design a water quality monitoring network can reduce the redundant monitoring nodes as well as save the costs for building and running a monitoring network. A novel algorithm is proposed to design an optimum water quality monitoring network for tidal rivers with bidirectional water flows. Two optimization objectives of minimum pollution detection time and maximum pollution detection probability are used in our optimization algorithm. We modify the Multi-Objective Particle Swarm Optimization (MOPSO) algorithm and develop new fitness functions to calculate pollution detection time and pollution detection probability in a discrete manner. In addition, the Storm Water Management Model (SWMM) is used to simulate hydraulic characteristics and pollution events based on a hypothetical river system studied in the literature. Experimental results show that our algorithm can obtain a better Pareto frontier. The influence of bidirectional water flows to the network design is also identified, which has not been studied in the literature. Besides that, we also find that the probability of bidirectional water flows has no effect on the optimum monitoring network design but slightly changes the mean pollution detection time.

Fabrication of multiwalled carbon nanotube-polyaniline/platinum nanocomposite films toward improved performance for a cholesterol amperometric biosensor.

A simple and high sensitive cholesterol amperometric biosensor, which is based on in situ electropolymerization of multi-walled carbon nanotube-polyaniline (MWCNT-PANI) nanocomposite and electrodeposition of platinum nanoparticle (nano-Pt) films onto the glassy carbon electrode surface for cholesterol oxidase immobilization, was constructed in this study. The preparation process of the modified electrode was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, and chronoamperometry. Because of the synergistic electrocatalytic activity between MWCNT-PANI nanocomposites and nano-Pt, the cholesterol biosensor exhibited an excellent performance with a linear range of 2.0-510.0 µM, a detection limit of 0.8 µM (signal-to-noise ratio = 3), a high sensitivity of 109.9 µA mM-1 , and a short response time within 5 Sec. Moreover, the reproducibility, stability, and selectivity of the biosensor were also investigated.

Synergistic effect of tartaric acid with 2,6-diaminopyridine on the corrosion inhibition of mild steel in 0.5 M HCl.

The inhibitive ability of 2,6-diaminopyridine, tartaric acid and their synergistic effect towards mild steel corrosion in 0.5 M HCl solution was evaluated at various concentrations using potentiodynamic polarization measurements, electrochemical impedance spectroscopy (EIS), and weight loss experiments. Corresponding surfaces of mild steel were examined by atomic force microscope (AFM), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) analysis. The experimental results are in good agreement and reveal a favorable synergistic effect of 2,6-diaminopyridine with tartaric acid, which could protect mild steel from corrosion effectively. Besides, quantum chemical calculations and Monte Carlo simulation were used to clarify the inhibition mechanism of the synergistic effect.