Substantial improvement is needed in efficient and affordable decolorization and disinfection methods to solve the issues caused by dyes and harmful bacteria in water and wastewater. This work involves the photocatalytic degradation of methylene blue (MB) as well as gram-negative and gram-positive bacteria by cobalt-doped tin oxide (Co-SnO₂) nanoparticles (NPs) and Co-SnO₂/SGCN (sulfur-doped graphitic carbon nitride) nanocomposites (NCs) under sunlight. The coprecipitation approach was used to synthesize the photocatalysts. Maximum methylene blue (MB) photocatalytic degradation was seen with the 7% Co-SnO₂ NPs compared to other (1, 3, 5, and 9 wt.%) Co-SnO₂ NPs. The 7% Co-SnO₂ NPs were then homogenized with different amounts (10, 30, 50, and 70 weight %) of sulfur-doped graphitic carbon nitride (SGCN) to develop Co-SnO₂/SGCN heterostructures with the most significant degree of MB degradation. The synthesized samples were identified by modern characterization methods such as FT-IR, SEM, EDX, UV-visible, and XRD spectroscopies. The Co-SnO₂/50% SGCN composites showed a significant increase in MB degradation and degraded 96% of MB after 150 min of sunlight irradiation. Both gram-negative (E. coli) and gram-positive (B. subtiles) bacterial strains were subjected to antibacterial activity. All samples were shown to have vigorous antibacterial activity against gram-positive and gram-negative bacteria, but the Co-SnO₂/50% SGCN composites exhibited the maximum bactericidal action. Thus, the proposed NC is an efficient organic/inorganic photocatalyst that is recyclable and stable without lowering efficiency. Hence, Co-SnO₂/50% SGCNNC has the potential to be employed in water treatment as a dual-functional material that simultaneously removes organic pollutants and eradicates bacteria.

Adsorption is a simple and effective method to remove heavy metal ions and anionic or cationic dyes from aqueous or waste solutions. Herein, we report on the adsorption of a cationic dye crystal violet on a low-cost natural material. The diatomite was obtained from Sig deposit (west of Algeria) and then treated with 1 M HCl solution. Natural clay (diatomite) was characterized using different physical-chemical methods, including, X-ray powder diffraction, X-ray fluorescence, thermogravimetric analysis, scanning electron microscopy, and Fourier transform infrared and pH of zero charge. The effect of various experimental parameters, such as initial dye concentration, adsorbent dose, initial pH, and shaking time on adsorption was investigated. The maximum adsorption capacity was found to be 82.0 mg.g^− 1 for treated Diatomite and 75.0 mg.g^− 1 for raw diatomite, with equilibrium reached within 120 min. Adsorption kinetics followed the pseudo-second-order model, with high correlation coefficients (R² = 0.998 for treated diatomite and R² = 0.999 for raw diatomite). The isotherm data showed the best fit with the Langmuir model. Optimal adsorption occurred at pH 8 for treated diatomite and pH 10 for raw diatomite.

Gulf countries experience an imbalance between water supply and demand, which leads to a dramatic decline in the amount of groundwater. Solar energy for water desalination is an attractive option in this region, where the climate is sunny all year. A very basic solar device called a single basin solar still is commonly used to convert available seawater into drinkable water. The issue of producing drinking water may be resolved by using this technique, but because of its low productivity, it is rarely used. The experiments were carried out on a south-facing, single slope solar still with a 23-degree inclination of the condensing cover from October to November 2022, on different days for different water depths. According to the findings, the solar still with 4 cm of depth (as compared to 5, 6, and 7 cm) exhibited the maximum water productivity (2.680 L/day) with an efficiency of 30%. When the solar still was equipped with an external mirror, the temperature in the basin was raised, and water productivity increased to 3.075 L/day with an improved efficiency of 35%. Further, the effects of wind velocity, ambient temperature, inner glass temperature, and intensity of solar radiation on daily productivity have been studied.

We demonstrate a new precursor route toward solution-processed films of the II-VI semiconductor zinc oxide (ZnO). Spray pyrolysis of aqueous solutions of the zinc salt zinc chloride (ZnCl₂) onto a substrate heated to at least 250 °C gives films that are insoluble in water, display an absorption edge at 365 nm, and when electrically gated display thin film transistor characteristics similar to ZnO films derived via the established zinc acetate (ZnAc) precursor route; we, therefore, identify it as ZnO. Control experiments attempting spray pyrolysis of aqueous zinc sulfate solutions, and delayed pyrolysis of cold-sprayed and dried ZnCl₂ films, do not lead to semiconducting films. Formation of ZnO from an aqueous Zinc salt requires the simultaneous presence of zinc ions, chloride ions, and water, at the time of pyrolysis. We, therefore, suggest that the actual ZnO precursor is the ZnCl_xH₂O_(4-x) species that forms when ZnCl₂ dissolves in water [The Journal of Chemical Physics 39, 3436 (1963)]. The reported process is easy to upscale for large area ZnO coatings, e.g., on window panes for thermal control, as no organic solvent vapors are released.