Humans are increasingly required to harvest green solar energy in order to reduce energy bills and save the environment from the excessive use of fossil resources. In this article, the microstructures of both commercial non-colored anodized Al and commercial blackened anodized Al were studied using optical and scanning electron microscopy in order to interpret the results of their use as solar absorbing surfaces. Microscopic examination showed that the thickness of the anodization layers of the non-colored anodized Al and the blackened anodized Al were approximately 11 µm and 14 µm, respectively, and they were perfectly adhered to the mother Al. The corrosion rate of all studied Al surfaces was investigated using the potentiodynamic polarization technique in 3.5% NaCl as the corrosive medium. The blackened anodized Al surface exhibited the highest corrosion resistance, which made it the best surface for solar heating systems. Moreover, raw Al, matte black painted Al, and blackened anodized Al were tested as selective surfaces for solar radiation in different weather conditions. Our results demonstrated the superiority of the blackened anodized Al in terms of the ability to absorb solar radiation, in addition to its higher corrosion resistance properties. In experimental testing, temperature values higher than 90 °C were reached several times. A gain of an extra 5 °C was achieved when using a double-glazed cover in comparison with a single-glazed setup. In conclusion, we highly recommend using a commercial blackened anodized Al surface to manufacture solar absorbing heaters, owing to its similarity in solar radiation absorptivity with the commercial matte black painted Al, excellent corrosion resistance, superior endurance upon long-term exposure to solar radiation, light weight, low price, and availability. Additionally, the light reflectance % test demonstrated the characteristics of the used solar selective surfaces.

The aim of this research is to study the anticorrosive behavior of a coating consisting of modified montmorillonite nanoclay as an inorganic green inhibitor. The anticorrosion protection for mild steel in 1.0 M HCl solution is studied via weight loss, electrochemical methods, SEM, and XRD. The results proved that montmorillonite nanoclay acts as a good inhibitor with a mixed-type character for steel in an acidic solution. Both anodic and cathodic processes on the metal surface are slowed down. There is a clear direct correlation between the added amount of montmorillonite nanoclay and the inhibition efficiency, reaching a value of 75%. The inhibition mechanism involves the adsorption of the montmorillonite nanoclay onto the metal surface. Weight loss experiments are carried out with steel samples in 1.0 M HCl solution at room temperature, and the same trend of inhibition is produced. SEM was used to image the surface at the different stages of the corrosion inhibition process, and also to examine the starting nanoclay and steel. XRD was used to characterize the nanoparticle structure of the coating. Montmorillonite nanoclay is an environmentally friendly material that improved the corrosion resistance of mild steel in an acidic medium.

In this study, a novel slow-release fertilizer (SRF) consisting of kaolinite and K₂SO₄ was prepared, employing the process of mechanochemical milling in a planetary ball mill. To obtain the optimum milling time and speed, several samples were made at fixed mass ratios of kaolinite: K₂SO₄ (3:1). The milling rotational speed ranged from 200 to 700 rpm for 120 min. Different milling times ranging from 60 to 180 min at fixed 600 rpm milling speed were also investigated to evaluate the incorporation of K₂SO₄ and to measure the liberation of K⁺ and SO₄²⁻ ions into solution. The properties of the studied samples were analyzed by Fourier transformation infrared spectrometry (FTIR), thermal gravimetric analysis (TGA), and ion chromatography (IC). The mechanochemical process is a green chemistry procedure that is successfully applied to incorporate K₂SO₄ into the amorphous kaolinite structure. The slow-release performance was evaluated by determining the K⁺ and SO₄²⁻ content in the aqueous solution upon leaching. The optimum released amount of K⁺ after 24 h was 32 mg L⁻¹ for the milling conditions of 180 min and 700 rpm, indicating that K₂SO₄-kaolinite has good slow-release properties. The novel SRF is cost-effective, environmentally friendly, and improves the fertilizer’s efficiency in many agricultural applications.

The Sun is a huge and clean energy source that must be relied upon to reduce greenhouse gases and promote the renewable and sustainable energy transition. In this paper, the testing of Al, Cu, and Fe metals with different thicknesses, both bare and painted matte black, was investigated for solar water heating systems. The used technique was a direct contact flat solar heating system (DCFSHS). Many experiments were run to assess this system in terms of metals’ thicknesses and their thermal conductivities as well. Thicknesses of around 0.35 mm and 1 mm of Cu gave almost similar feedback. Maximum temperatures in the range of 93–97 °C were achieved during the autumn season in Amman, Jordan, while it was approximately 80 °C in winter. It has been confirmed that high water temperatures can be obtained in all used metals, regardless of their thermal conductivities. It was also found that a white color of the solar heater case inner wall leads to an increase in water temperature of approximately 4 °C in comparison to a black color. Furthermore, a light reflectance % test in the wavelength range of 240–840 nm for the studied metals, with both bare and black-painted surfaces, gave a superb result that was in line with the obtained results of the DCFSHS. Our innovative system design for solar water heating is due to improvements in many aspects, such as design, production costs, environment, and weight.

Galena is a natural mineral enriched with lead sulfide (PbS). It typically forms in hydrothermal veins associated with igneous rocks and can also occur as a gangue mineral in other ore deposits. PbS is of special importance for scientific research applications due to the possibility of tuning its semiconductor energy gap using nanotechnology in conjunction with powder metallurgy as an easy, controllable production route. In this paper, almost pure PbS was successfully produced starting from a high ratio of PbS phase galena ore. As-received galena lumps were roughly pulverized and milled to produce four particle size ranges of 38, 63, 125, and 250 µm prior to compaction and sintering in a vacuum (pre-flushed with argon gas). SEM coupled with the EDAX analysis unit was employed to investigate the microstructure and chemical composition of the as-received galena and the subsequent products after sintering. The chemical analysis confirmed the high ratio of PbS compound in the as-received galena and sintered products with approximately 85% Pb and 13% S mass ratio. The sintering process of the galena powder was carried out at different values of temperature, time, and compaction pressure. Additionally, the effect of length to diameter ratio of compacted and sintered samples was investigated. XRD analysis confirmed the existence of the PbS phase in the as-received and sintered samples at 700 °C with approximately 98 wt.%, as well as a new phase that is formed at 800 °C with a lower percentage. The micro-hardness of the as-received and sintered samples was measured and compared with the as-received galena ore. The results showed a significant reduction in the hardness of sintered galena powder compared with the bulk as-received galena by 52%. Furthermore, a relative sintered density of 99.3% for the as-received galena density signifies a novel result using powder metallurgy techniques.

Nanoscale zinc sulfide (ZnS) powders have attracted considerable interest due to their unique properties and diverse applications in various fields, including wastewater treatment, optics, electronics, photocatalysis, and solar systems. In this study, nano-powder ZnS was chemically synthetized starting from Zn powder, diluted HCl, and laboratory-prepared Na2S. The obtained ZnS was studied using an SEM coupled with EDS, XRD analysis, UV–Visible spectroscopy, and FTIR techniques. The XRD results showed that the synthesized nanoscale ZnS powder was approximately 2.26 nm. Meanwhile, the EDS and XRD patterns confirmed the high purity of the obtained ZnS powder. In addition, the ZnS powder was compacted and sintered in an argon atmosphere at 400 °C for 8 h to prepare the required pellets for thin-film deposition via E-beam evaporation. The microscopic structure of the sintered pellets was investigated using the SEM/EDS. Furthermore, the optical properties of the deposited thin films were studied using UV–Visible spectroscopy in the wavelength range of 190–1100 nm and the FTIR technique. The bandgap energies of the deposited thin films with thicknesses of 111 nm and 40 nm were determined to be around 4.72 eV and 5.82 eV, respectively. This article offers a facile production route of high-purity ZnS powder, which can be compacted and sintered as a suitable source for thin-film deposition.