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Guar gum is recently being extensively used in a broad range of applications because of its distinctive physico-chemical properties. Guar gums have been used to prepare different concrete specimens. After the guar gum concrete has been scrutinized, the binding characteristics of the concrete are determined. Experimental studies using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDS), scanning electron microscopy (SEM), and quantum chemical calculations revealed that guar gum effectively protects structural steel from corrosion. The experimental analyses showed that 1.4% of guar gum exhibited maximum protection exhibited from maximum surface orientation values as 0.7874 and the same is fixed as optimum dose to examine the cooperative effect of counter ions on the corrosion progression. Furthermore, Monte Carlo (MC) simulations were used to investigate the surface interactions between the inhibitors and the metal surface. Finally, the results indicated that the ingredients of Guar Gum such as Mannose, Galactose, and Galactomannan have strong interactions with the surface of Fe (110) and thus have processed modelling inhibition strength against metal corrosion.

Abstract The corrosion inhibition behavior of sodium nitrite (NaNO2) towards pure copper (99.95%) in simulated cooling water (SCW) was investigated by means of electrochemical impedance spectroscopy (EIS) and dynamic electrochemical impedance spectroscopy (DEIS). NaNO2 interferes with metal dissolution and reduce the corrosion rate through the formation or maintenance of inhibitive film on the metal surface. Surface morphologies illustrated that the surface homogeneity increased on adding sodium nitrite. Sodium nitrite’s adsorption on copper surface followed the modified form of Langmuir, Freundlich and Frumkin isotherms. Physiosorption mode was involved in the corrosion protection. Electrochemical results revealed an corrosion resistance of copper increases on increasing the inhibitor concentration. The DEIS results indicated that copper corrosion mechanism could be hindered by 50% even after interval of 24 h by optimum concentration of sodium nitrite. The maximum inhibition was achieved with 2000 ppm of NaNO2. With this concentration, inhibition efficiency of up to 61.8% was achievable.

The quantitative structure–property relationship (QSPR) models of the inhibition efficiency of seventeen α-amino acids for copper in acidic medium to their calculated reactivity indicators were developed. DFT calculations and Monte Carlo simulations were employed to find out these indicators. Both multi-linear regression (MLR) and artificial neural network (ANN) methods were employed. The most relevant global descriptors were selected using the simulated annealing algorithm. The QSPR studies showed that the inhibiting performance of the investigated compounds was influenced by their electronegativity, LUMO energy, fraction of electron transferred and total negative charge. The results show that the ANN based model exhibits a great predictive performance compared with MLR model according to correlation coefficient and the root-mean-squared error. In addition, this indicates that the corrosion inhibition of copper by these α-amino acids is mainly a complex phenomenon. Moreover, by analysis of local reactivity indicators and using the ANN constructed model, ten new designed derivative compounds with their predicted inhibition efficiency were proposed. Keywords: Corrosion, Modeling, DFT, Monte Carlo, Simulated annealing, QSPR

The energies of frontiers molecular orbitals and derived electronic parameters are widely used to explain experimentally obtained inhibition effectiveness of several organic inhibitors against metallic corrosion. In this context, the present study aims to reevaluate the use of solvation free energy (ΔGSolv) as an additional parameter for the corrosion inhibition inspection. Three organic molecules set previously reported as corrosion inhibitors in acidic solutions were selected to conduct this in silico study. The solvation free energy in the aqueous phase of chosen inhibitors was determined using DFT-based calculations in combination with integral equation formalism-polarizable continuum solvation model. The acquired data show that ΔGSolv can be used together with other known parameters to inspect the inhibition performance of organic inhibitors in acidic media.

This study was performed to investigate the electrochemical oxidation of a solution containing methylene blue dye by using a tin oxide (SnO2) electrode. The effect of several operating factors such as electrolyte types, current density, initial dye concentration, and pH were investigated by following the discolorationand COD removal. The results show that the maximum color was removed by using chloride supporting electrolyte (i.e. KCl and NaCl) indicating that the indirect oxidation was promoted by the strong oxidant species (i.e. Cl2 and ClO–) generated at the anode surface. The best experimental conditions were attained for i = 60mA/cm2, 1% KCl and pH = 3, in which 100% of color was removed after 30 minutes and the COD removal reached 80.9% after 120 min. These results reveal that the anodic oxidation technique using SnO2 electrode could be used to remove the methylene blue dye from textile wastewater.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The electrochemical oxidation of the Rhodamine B dye (Rh-B) was carried out using dimensionally stable type anode (DSA, Ti/Ru0.3Ti0.7O2). The work was performed using the electrochemical flow cell system. The effect of several operating factors, such as supporting electrolytes, current density, electrolysis time, temperature, and initial concentration of Rh-B dye, were investigated. The UV-visible spectroscopy and chemical oxygen demand (COD) measurements were conducted to monitor the removal and degradation of Rh-B. The best color removal achieved was found to be 98.3% after 10 min applying 3.9 mA·cm−2 as a current density using 0.07 mol·L−1 of NaCl. Meanwhile, the highest COD removal rate (93.0%) was obtained for an applied current density of 3.9 mA·cm−2 as the optimal operating condition after 180 min reaction time, with 2.98 kW h·m−3 as energy consumption. This shows that the best conditions for color removal are not certainly the same as those for the COD removal. The rises in the concentration of NaCl, and applied current increased the Rh-B color removal rate. The decline in Rh-B dye concentration followed pseudo-first-order kinetics. The obtained values of apparent rate constant were increased by increasing chloride ion concentration. It is concluded that the electro-oxidation on DSA electrode using a flow cell is a suitable process for the removal of Rh-B dye in aqueous solutions.