Unveiling green corrosion inhibitor of Aloe vera extracts for API 5L steel in seawater environment.

This study evaluated Aloe vera extract as a green inhibitor to prevent corrosion in seawater environments. A. vera extract was produced by maceration with methanol-water at room temperature. Electrochemical techniques were used to evaluate the corrosion inhibitor effectiveness of the A. vera extract. The morphology of the corrosion products was analyzed by FE-SEM equipped with EDS and AFM. FT-IR and LCMS characterized the functional and structural groups in this extract. The electrochemical measurements show that A. vera extract could effectively reduce the corrosion of API 5L steel in seawater environments. Inhibition efficiency (IE) increases with increasing concentration. Optimal corrosion inhibition efficiency of around 83.75% (PDP) and 88.60% (EIS) was obtained by adding 300 mg L-1 of extract at 310 K. Furthermore, the higher the concentration of A. vera extract, the greater the activation energy (Ea), with the highest activation energy being 48.24 kJ mol-1 for the concentration of 300 mg L-1. Conversely, increasing the temperature and exposure duration reduces the corrosion inhibition efficiency (IE) values; the best exposure period was 30 min with 88.34% IE by a concentration of 300 mg L-1 at 300 K. This corrosion inhibition is achieved by the adsorption process of A. vera bioactive on metal surfaces with a mixed inhibitor through a physisorption-chemisorption mechanism. This finding was confirmed by the smoother surface morphology of the steel treated with A. vera extract than without. This unveiling investigation found that A. vera extract has the potential to be an environmentally friendly corrosion inhibitor in the seawater environment.

Analysis of the Antibacterial Activity and the Total Phenolic and Flavonoid Contents of the Moringa oleifera Leaf Extract as an Antimicrobial Agent against Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a bacterium that causes metal deterioration by forming biofilms on metal surfaces. This work was carried out to analyze the antibacterial activity and the phenolic and flavonoid contents of the Moringa oleifera leaf extract against Pseudomonas aeruginosa. M. oleifera leaves were extracted in a methanol solution at different concentrations. The M. oleifera leaf extract yields were 12.84%, 18.96%, and 19.64% for the 100%, 75%, and 50% methanol ratios, respectively. Extracts of M. oleifera leaves had a minimum inhibiting concentration (MIC) of approximately 6144 µg/mL against P. aeruginosa for a ratio of 100% methanol. In addition, no antibacterial activity was found for the 75% and 50% methanol ratios. The total phenolic levels were 16.26%, 12.73%, and 12.33% for the 100%, 75%, and 50% methanol solvent ratios, respectively. The total amounts of flavonoids were 23.32%, 3.40%, and 0.64% for the 100%, 75%, and 50% methanol solvents, respectively. The chemical structure of M. oleifera consists of kaemferol-3-O-rutinoside, quercimeritrin, kaempferol-3-O-ß-D-glucopyranoside, stearidonic acid, trichosanic acid, pyrophaeophorbide A, and stigmastan-3,6-dione. The concentration of the solvent is essential in the extraction of plant constituents. Different concentrations indicate differences in antibacterial activity, phenolic and flavonoid contents, and chemical structure.

Hard magnetic and broadband microwave absorption characteristics of heat-treated Pr15-XDyXFe77B8(x = 0, 1, 2, and 3) alloys.

In this study, fabrication of Pr15-xDyxFe77B8 (at.%) alloys with x = 0, 1, 2, and 3 compositions was performed with a mini vacuum arc melting furnace. The alloys were successively annealed in an inert atmosphere for microstructure homogenization. All alloys exhibit the typical characteristics of a permanent magnet. The coercivity gradually increases with increasing atomic fraction of Dy. The heat treatment applied to the samples changed the properties from those of a permanent magnet to those of a microwave absorber. The reflection loss (RL) value evaluated by a Vector Network Analyzer (VNA) shows broadband absorption characteristics in the full 8 GHz-12 GHz frequency range. The RL and bandwidth increase with the addition of the Dy substitute. The as-cast and annealed Pr15- xDyxFe77B8 alloy with the x = 1 composition shows superior absorption, starting from the 8 GHz frequency and increasing progressively, reaching less than -17 dB or an absorption of more than 85.0 % at a peak frequency of 10.5 GHz, after which it weakens to -6 dB at a frequency close to 12 GHz. Heat-treated samples were characterized by absorption with two almost overlapping absorption peaks at frequencies of 9.5 GHz and 11.5 GHz, leading to very broadband absorption across the full frequency range (8-12 GHz). It is concluded that permanent magnetic materials could be converted into radar absorbing materials (RAM). RAM based on heat-treated rare earth permanent magnet has broadband absorption characteristics.