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

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

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

Effectiveness of NPK Fertilizer-Saw Dust Amendment on Biodegradation of Crude Oil in Polluted Soil

Soil pollution by crude oil causes nitrogen imbalance and impedes the flow of air and nutrient. Biostimulation improves thisnutrient and aeration and enhances the rate of biodegradation of the pollutants. This study was undertaken to use biostimulationto strategically biodegrade crude oil in polluted soil. Optimization of NPK fertilizer (61:15:15) and sawdust enhances optimum growth of hydrocarbon-degrading microorganisms with a resultant restoration of the soil. Nine treatment cells (A, B, C, D, E, F,G, H, I) and control (J) were subjected to various treatment combinations according to the experimental design. The resultingresidual concentrations of total petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbon (PAH) are indicators of thesoil restoration. Moreover, the degradation efficiency for TPH ranged between 98.14% and 99.05% and the biodegradation kinetics rate between -0.0419 and -0.0479 per day while microbial kinetics growth rate varied between 0.1840 and 0.1931 per day in a 105 day bioremediation time. However, the percentage utilization of nitrogen and phosphorus were between 85.1%, 81.5% to 92.3%, 92.8% respectively. Interaction between the process independent variables provided both nutrient and favorable medium suitable for microbial activities for optimum treatment. Sawdust combined with NPK fertilizer is therefore effective for treating and restoring a hydrocarbon polluted soil

Theoretical and experimental studies on the corrosion inhibition potentials of some purines for aluminum in 0.1M HCl

AbstractExperimental aspect of the corrosion inhibition potential of adenine (AD), guanine (GU) and, hypoxanthine (HYP) was carried out using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods while the theoretical aspect of the work was carried out by calculations of semi-empirical parameters (for AM1, MNDO, CNDO, PM3 and RM1 Hamiltonians), Fukui functions and inhibitor–metal interaction energies. Results obtained from the experimental studies were in good agreement and indicated that adenine (AD), guanine (GU) and hypoxanthine (HYP) are good adsorption inhibitors for the corrosion of aluminum in solutions of HCl. Data obtained from electrochemical experiment revealed that the studied purines functioned by adsorption on the aluminum/HCl interface and inhibited the cathodic half reaction to a greater extent and anodic half reaction to a lesser extent. The adsorption of the purines on the metal surface was found to be exothermic and spontaneous. Deviation of the adsorption characteristics of the studied purines from the Langmuir adsorption model was compensated by the fitness of Flory Huggins and El Awardy et al. adsorption models. Quantum chemical studies revealed that the experimental inhibition efficiencies of the studied purines are functions of some quantum chemical parameters including total energy of the molecules (TE), energy gap (EL–H), electronic energy of the molecule (EE), dipole moment and core–core repulsion energy (CCR). Fukui functions analysis through DFT and MP2 theories indicated slight complications and unphysical results. However, results obtained from calculated Huckel charges, molecular orbital and interaction energies, the adsorption of the inhibitors proceeded through the imine nitrogen (N5) in GU, emanine nitrogen (N7) in AD and the pyridine nitrogen (N5) in HPY

CoPi/Co(OH)2 Modified Ta3N5 as New Photocatalyst for Photoelectrochemical Cathodic Protection of 304 Stainless Steel

In this work, CoPi and Co(OH)2 nanoparticles were deposited on the surface of Ta3N5 nanorod-arrays to yield a novel broad-spectrum response photocatalytic material for 304 stainless steel photocatalytic cathodic protection. The Ta3N5 nanorod-arrays were prepared by vapor-phase hydrothermal (VPH) and nitriding processes and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis spectroscopy, respectively, to obtain morphologies, crystal structures, surface compositions, and light response range. In order to analyze the performance improvement mechanism of CoPi/Co(OH)2 on Ta3N5 nanorod-arrays, the electrochemical behavior of modified and unmodified Ta3N5 was obtained by measuring the open circuit potential and photocurrent in 3.5 wt% NaCl solution. The results revealed that the modified Ta3N5 material better protects 304 stainless steel at protection potentials reaching −0.45 V

Effects of Heat Treatment on the Electrochemical Corrosion Behaviour of Aluminum Alloy AA8011 in 0.1M H 2 SO 4 Aqueous Acid Media

Abstract The effects of heat treatment and quenching regimens on the electrochemical corrosion behaviour of aluminium alloy AA8011 in 0.1M H 2 SO 4 was studied by open circuit potential (OCP), potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) measurements. Three different specimens (unheated, air quenched and oven quenched) were investigated. Polarization results show that all the specimens underwent active dissolution, with no distinct transition to passivation. Heat treatment caused the corrosion potential to shift; the oven quenched shifted to the more cathodic region, while the air quenched shifted to the anodic values. There was decrement in the rate of both cathodic and anodic partial reactions of the corrosion processes in the heat treated samples. The impedance spectra for all the specimens comprised of a high frequency capacitive loop and an inductive loop at low frequency and depict higher values of the charge transfer resistance for the heat treated specimens. All the results indicate that heat treatment increased the corrosion resistance of AA8011 in 0.1M H 2 SO 4 with modifying the corrosion mechanism. The corrosion resistance obtained from the impedance measurements increased in the order unheated< air quenched < oven quenched. This trend has been correlated with the phase constituents of the different specimens as determined from the X-ray diffraction (XRD), and scanning electron microscopy (SEM)