Hypoxanthine as an Inhibitor for Mild Steel Corrosion in 0.1 M HCl

Hypoxanthine (HYP) has been evaluated as a corrosion inhibitor for mild steel in aerated 0.1 M hydrochloric acid by weight loss, potentiodynamic polarisation and electrochemical impedance spectroscopy techniques at 30 and 60 °C respectively. The results showed that hypoxanthine is a moderate inhibitor in the acidic medium. Potentiodynamic polarisation results revealed hypoxanthine to be a mixed inhibitor. Inhibition efficiency increased with increase in the concentrations of hypoxanthine but decreased with a rise in temperature of 60 °C . The adsorption of the inhibitor on the mild steel surface is found to obey Langmuir adsorption isotherm. From the values of Ea and G°ads obtained, the mechanism of physical adsorption is proposed for the inhibitive action of hypoxanthine. Key Words: acid solutions, adsorption, inhibition efficiency, potentiodynamic polarisatio

Electrochemical and microbial treatment of bromophenol blue dye in aqueous solution

Bromophenol blue (BB) is an important triphenylmethane derivative widely used in research and industry as a dye or colorant for silk, leather, and drugs. BB has a high proclivity for water contamination because of its high solubility and stability, causing damage to living organisms even in low quantities. This study assessed the feasibility of electrochemical and biological for the decolorization of BB using graphite-copper electrode and indigenous microorganisms, respectively. It was found that effectiveness of electrochemical treatment improves with higher electrolysis time, current density, and electrolyte concentration, drops with rising pH, and shows a nonlinear pattern with temperature. The microbial strains identified as Acinetobacter baumaniu, Serratia marcescens, Aspergillus niger, Aspergillus flavus, Bacillus megaterium, Rhizopus stolonifer, and Bacillus subtilis performed poorly, irrespective of the dye/mineral salt ratio. The electrochemical technique was much more effective for decolorizing bromophenol blue dye-contaminated water. The computational results showed clearly that bromine atoms are the most susceptible sites for attack by oxidizing species and, thus, the onset of BB-decolorization

Interkristalna korozija Cu-Al-Ni legure u 0.5 mol dm–3 H2SO4 otopini

The corrosion behaviour of Cu-Al-Ni alloy in 0.5 mol dm–3 H2SO4 solution was investigated by electrochemical methods including open circuit potential measurement, electrochemical impedance spectroscopy measurements, linear and potentiodynamic polarization. Measurements were performed in 0.5 mol dm–3 H2SO4 at temperatures 20 and 40 °C. After polarization testing, corroded electrode surfaces were ultrasonically cleaned in deionized water and examined by light and scanning electron microscopy, while the elemental composition at individual points of the alloy surface was determined by EDS analysis. The results of the investigations revealed the occurrence of intergranular corrosion on the Cu-Al-Ni surface, which became more pronounced with increasing temperature. This work is licensed under a Creative Commons Attribution 4.0 International License.Korozijsko ponašanje Cu-Al-Ni legure u 0,5 mol dm–3 H2SO4 otopini ispitivano je elektrokemijskim metodama kao što su mjerenje potencijala otvorenog strujnog kruga, mjerenje metodom elektrokemijske impedancijske spektroskopije, linearne i potenciodinamičke polarizacije. Mjerenja su provedena u 0,5 mol dm–3 H2SO4 pri temperaturama od 20 i 40 °C. Nakon polarizacijskih mjerenja korodirane površine elektroda ultrazvučno su očišćene u deioniziranoj vodi i ispitane svjetlosnim i pretražnim elektronskim mikroskopom, dok je elementarni sastav na pojedinim točkama na površini određen EDS analizom. Rezultati ispitivanja pokazali su da dolazi do interkristalne korozije na površini Cu-Al-Ni legure, čiji intenzitet raste s povećanjem temperature elektrolita. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna

Review of forms of corrosion and mitigation techniques: A visual guide

Over the years, issues relating to corrosion have been a serious challenge confronting effective scientific and engineering applications of metallic materials in the industry. Annual loss due to corrosion issues has been quite alarming as it runs into trillions of dollars. In this review, forms of corrosion, factors affecting each form, mechanism of formation, and different aggressive environments that propagate corrosion have been identified. Mitigation techniques against this threat were all discussed, especially those involving the use of eco-friendly, cheap, available, and non-toxic materials. It was observed that the principle, process, and conditions governing each form of corrosion must be well understood before it can be effectively mitigated. This can be done either by proper material selection and design, environmental measures, modification and engineering design, modification of corrosive media, use of inhibitors, or sacrificial and protective coatings. However, adequate knowledge of the environment and nature of metal to be deployed in such an environment is essential in ensuring such material's protection, safety, and durability. For efficient and effective corrosion prevention and control, these mitigation techniques can either be implored exclusively or collectively depending on the material's nature and the setting in which it will be used

Corrosion Protection of Copper in Sodium Chloride Solution using Propolis

In this investigation the possibility of inhibiting corrosion of copper using ethanol extract of propolis in 0.5 mol dm-3 NaCl solution was investigated. The measurements were carried out in 200 cm3 of NaCl solution to which 4 ml of ethanol extract of propolis was added. Also, the protective effect of propolis coating, which was formed by applying the ethanol extract of propolis to the electrode surface, followed by air drying for 24 h, was investigated. Experiments were performed using electrochemical methods: open circuit potential measurements, linear and potentiodynamic polarization method and electrochemical impedance spectroscopy measurements (EIS). The results showed that the coating of propolis significantly shifted the value of the open circuit potential of Cu to more positive values, significantly increased the value of polarization resistance and as well led to a reduction in corrosion current density. On the other hand, addition of propolis in solution yielded minor changes in the value of the stable open circuit potential of copper, but increased the value of polarisation resistance and decreased the corrosion current density. After polarisation measurements, the electrode surface was examined by optical microscopy. Quantum chemical modelling of selected constituents of propolis was undertaken in order to ascertain their contributions to the corrosion inhibition performance

Adsorption and corrosion inhibition characteristics of 2–(chloromethyl) benzimidazole for C1018 carbon steel in a typical sweet corrosion environment: Effect of chloride ion concentration and temperature

Benzimidazole derivatives are emerging as promising corrosion inhibitors for oil and gas application because they exhibit high efficiency and very good environmental profile. Although long alkyl and phenyl chains enhance their efficiency, they also increase their toxicity. Finding benzimidazole derivatives devoid of long hydrocarbon chains and with lower toxicity has become a priority. 2–(chloromethyl)benzimidazole (CMB), with log Po/w = 2.2, has been investigated as a promising low-toxic sweet corrosion inhibitor for C1018 carbon steel in CO2–saturated NaCl solution under static condition using experimental and theoretical approaches. At 25 ◦C, Open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) techniques confirm that CMB is an anodic-type sweet corrosion inhibitor which is able to form a protective layer on the steel surface and provide inhibition efficiency of 97.54% at 10 ppm. The efficiency increased to 98.40% and 98.58% upon increasing the temperature to 40 ◦C and 60 ◦C, respectively but decreased to 96.32% and 94.76% as the salt concentration was raised to 5.0% and 7.0% NaCl, respectively. The latter was attributed to the antagonistic competition between Cl– ions and CMB for anodic adsorption. The CMB–steel interaction is facilitated by the free electrons around N heteroatoms and C = C bonds, based on FTIR analysis and computational calculations. This eventually ameliorates the surface degradation of the steel during the sweet corrosion at 25 and 60 ◦C. CMB performance is highly comparable with reported sweet corrosion inhibitors with higher toxicity values

Emergence and spread of two SARS-CoV-2 variants of interest in Nigeria.

Identifying the dissemination patterns and impacts of a virus of economic or health importance during a pandemic is crucial, as it informs the public on policies for containment in order to reduce the spread of the virus. In this study, we integrated genomic and travel data to investigate the emergence and spread of the SARS-CoV-2 B.1.1.318 and B.1.525 (Eta) variants of interest in Nigeria and the wider Africa region. By integrating travel data and phylogeographic reconstructions, we find that these two variants that arose during the second wave in Nigeria emerged from within Africa, with the B.1.525 from Nigeria, and then spread to other parts of the world. Data from this study show how regional connectivity of Nigeria drove the spread of these variants of interest to surrounding countries and those connected by air-traffic. Our findings demonstrate the power of genomic analysis when combined with mobility and epidemiological data to identify the drivers of transmission, as bidirectional transmission within and between African nations are grossly underestimated as seen in our import risk index estimates

Investigating the extract constituents and corrosion inhibiting ability of Sida acuta leaves

Constituents of the ethanol extract of Sida acuta (SA) leaves were investigated by phytochemical, GC-MS and FTIR studies and its corrosion inhibition effects on mild steel was studied in 1 M HCl and 0.5 M H2SO4 solutions, using gravimetric and electrochemical methods of corrosion monitoring. The surface morphology of the mild steel surface before and after corrosion was also assessed using SEM imaging. The phytochemical, GC-MS and FTIR results revealed that SA contains carbonyl groups, aromatic rings, and double bonds that make it a prospective corrosion inhibitor for mild steel. Moreover, gravimetric results indicated that SA is an effective additive for the corrosion of mild steel at all the concentrations studied. Finally, the electrochemical results showed that SA inhibited both the anodic and cathodic half reactions by the adsorption of the extract constituents on the mild steel surface; this was further confirmed by the SEM investigations