Wearing face masks, use of respirators, social distancing, and practicing personal hygiene are all measures to prevent the spread of the coronavirus disease (COVID-19). This pandemic has revealed the deficiency of face masks and respirators across the world. Therefore, significant efforts are needed to develop air filtration and purification technologies, as well as innovative, alternative antibacterial and antiviral treatment methods. It has become urgent—in order for humankind to have a sustainable future—to provide a feasible solution to air pollution, particularly to capture fine inhalable particulate matter in the air. In this review, we present, concisely, the air pollutants and adverse health effects correlated with long- and short-term exposure to humans; we provide information about certified face masks and respirators, their compositions, filtration mechanisms, and the variations between surgical masks and N95 respirators, in order to alleviate confusion and misinformation. Then, we summarize the electrospun nanofiber-based filters and their unique properties to improve the filtration efficiency of face masks and respirators.

A membrane composed of polyethylene terephthalate nanofiber and multi-walled carbon nanotubes (PET NF-MWCNTs) composite is used to adsorb methylene blue (MB) dye from an aqueous solution. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction techniques are employed to study the surface properties of the adsorbent. Several parameters affecting dye adsorption (pH, MB dye initial concentration, PET NF-MWCNTs dose, and contact time) are optimized for optimal removal efficiency (R, %) by using the Taguchi L25 (54) Orthogonal Array approach. According to the ANOVA results, pH has the highest contributing percentage at 71.01%, suggesting it has the most significant impact on removal efficiency. The adsorbent dose is the second most affected (12.08%), followed by the MB dye initial concentration of 5.91%, and the least affected is the contact time (1.81%). In addition, experimental findings confirm that the Langmuir isotherm is well-fitted, suggesting a monolayer capping of MB dye on the PET-NF-MWCNT surface with a maximum adsorption capacity of 7.047 mg g−1. Also, the kinetic results are well-suited to the pseudo-second-order model. There is a good agreement between the calculated (qe) and experimental values for the pseudo-second-order kinetic model.

Even though various synthetic compounds have a well action as anticorrosive, they are not cheap and are toxic to both environment and humans. Nevertheless, in C-steel, there is a vital concern, which is serious corrosion issues happen through exposure to environments of aggressive acidity i.e., descaling, oil well solutions of acidity, and pickling. Hence, this study aimed to evaluate the inhibition effect of wild onion (WO) extract as an eco-friendly inhibitor on the behavior of corrosion for C-steel in 0.5 M HCl through the conventional weight loss approach. Various concentrations (0%, 0.5%, 1%, 1.5%, 2%, and 2.5%) of inhibitor in various times of immersion (2, 4, and 8 h) and at different temperatures (25°C, 35°C and 45°C) were investigated for their C-steel corrosion inhibition in corrosive media. In the presence and absence of the inhibitor, the corrosion rate (CR) was investigated as affected by temperature. The concentration of the inhibitor and temperature-controlled the inhibition efficiency %E of the inhibitor. At the existence of wild onion extract, the ideal efficiency of inhibition for C-steel was 98.95%, 88.99%, and 86.79% at 2.5% inhibitor concentrations at the preceding temperatures, respectively. It was noticed that adsorption was spontaneous and physical as proved through adsorption value of free energy ΔG°ads (‒13.5 kJ/mol) and also fitted Langmuir adsorption isotherm. The surface coverage θ and corrosion current density Icorr data confirmed the previous result where inhibition is due to the adsorption of physical nature for the components of the additive on the C-steel surface.

Corrosion is a common concern that arises from the use of iron metal components in daily life, both at home and industrial scale. Cathodic protection employing a sacrificial anode is one of several ways for preventing iron corrosion and it is a common industrial method for preventing corrosion in underground pipes, ships, and storage tanks. The two basic components of the cathodic protection method are the metal to be protected, a second metal is used as a sacrificial anode to prevent corrosion. This study involved preparing corrosive cells with different pH corrosive media (1,3,5,7,9 and11) in different immersion times (30, 60, and 90 days). It aimed to apply the principle of sacrificial anodes by using zinc and iron as sacrificial anodes for the protection of iron and copper respectively. The magnitudes of the percentage of corrosion (% corrosion) and corrosion rate (CR) were observed by the weight loss method for Fe without protection, Fe/Zn couple, and Fe/Cu couple. The CR varies with varied immersion times and acid-alkaline concentrations. The results show a large % corrosion and CR in acidic media, with varying degrees, compared to the alkaline and neutral media. At pH=1 and 90 days immersion time, the % corrosion reached 92.26% and CR reached 102.33 mpy, this proved that the acidic media accelerated the corrosion of iron. Promising results were obtained in which corrosion rates were reduced and determined by applying for protection with the sacrificial anode. The CR of iron declined from 102.33 mpy to 13.31 mpy at pH=1 and after 90 days for Fe/Zn couple. Whereas, CR of Fe/Cu couple increased significantly from 13.31 mpy to 30.94 mpy at pH=1 and after 90 days when it compared with the CR of Fe/Zn couple.