The increasing presence of pharmaceutical pollutants, such as acetaminophen, in water bodies poses a significant environmental challenge due to their persistence and potential toxicity. This study investigated the enhanced photodegradation of acetaminophen using ZnO-NiO nanofibers as superior photocatalysts. The nanofibers synthesized with varying NiO contents (designated as ZN0.5, ZN1, ZN1.5, and ZN2), were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, FTIR, Brunauer–Emmett–Teller (BET) analysis, and diffuse reflectance spectroscopy (DRS) to elucidate their structural, morphological, and optical properties. Thermogravimetric analysis (TGA) indicated that the nanofibers exhibit high thermal stability, with major weight loss attributed to the decomposition of the polymer matrix and residual organics. The BET analysis revealed that the specific surface area remains stable after increasing the NiO content up to a certain ratio. This stability correlates with the enhanced photocatalytic performance due to increased light absorption and improved charge separation. The diffuse reflectance spectra and Kubelka–Munk plots demonstrated a reduction in bandgap energy with higher NiO content, facilitating greater visible light absorption. Photocatalytic experiments under visible light irradiation, in the presence of peroxymonosulfate (PMS), showed that the ZN1.5 nanofibers achieved the highest acetaminophen degradation rate, i.e., 92%, within 3 h. Mechanistic studies, supported by radical trapping experiments, revealed that the improved photocatalytic efficiency is due to the synergistic effects of ZnO and NiO heterojunctions, which enhance charge separation and reactive oxygen species (ROS) generation. This research highlights the potential of ZnO-NiO nanofibers as effective photocatalysts for the degradation of pharmaceutical pollutants. The findings demonstrate that optimizing the composition and structure of nanofibers can significantly improve their environmental remediation capabilities, providing a promising solution for sustainable water treatment.

Coliforms (FB) posing population health risks in groundwater (GW) have been identified for decades, with recent studies assessing how hydrogeological and non-hydrogeological parameters correlate with their presence. This study focused on explaining the physicochemical and hydrological factors influencing the presence of fecal contamination in the GW system of Ad-Dawadmi, KSA, a hyperarid area facing a prolonged drought. It was designed and implemented by sampling 47 working wells and their laboratory analysis. The data analyses indicated that the salinity exhibited a purification effect such that at levels higher than 3500 and 6000 mg/L, no E. coli and total coliform (TC) were detected. Heavy metals, especially copper, showed strong, hygienic effects at 195 and 300 µg/L thresholds for E. coli and TC, respectively, while those of Fe were at 1200 and 2000 µg/L. Nitrates, dissolved organic carbon (DOC), and dissolved oxygen (DO) showed a quasi-random interrelationship with FB. The occurrence of FB in boreholes up to 52 m below ground level (BGL) challenges the single water resource in the region. Integrating various analyses help constrain and provide multiple lines of evidence for the inferred remarks. This work presented some methodological aspects for understanding the effects of the physicochemical and hydrogeological factors on FB that may better protect water quality and improve human health outcomes.

Ensuring sustainability of groundwater (GW) resources requires understanding the interplaying factors in the hydrogeochemical evolution of the system (cause and effect relationships), which is the subject of the current work concerning the groundwater resource in a hyperarid region, namely, AdDawadmi, Saudi Arabia. Integration of geographical information system (GIS), statistical, graphical, and geochemical modeling approaches are adopted to achieve the study’s design intentions. Slicing the study area on a spatial basis helped yield insights into major constituents’ variation trends using the graphical methods that lack spatial representation capabilities, such as Piper, radial, and Durov plots. Localities of higher salinities, NO₃⁻, SO₄²⁻, Cl⁻, Na⁺, and Ca²⁺ are remarkable, indicating the effects of localized and point source activities and evaporation-driven concentrating processes rather than lithology supported by the largest regression and correlation coefficients for Cl⁻, Na⁺, and SO₄². Many interacting processes are identified: evaporation, vicious salinization cycle (VSC), rock weathering, ion exchange, and geomorphological-driven flow. Hydrogeochemical modeling using the Visual MINTEQ program concludes that concentration-driven evaporation might lead to the precipitation of significant SO₄²⁻ and Ca²⁺ along with CaCO₃ saturation. Such processes, coupled with the ion exchange, would greatly impact the GW chemical composition and affect the aquifer and soil properties such as permeability. Human activities impact the GW system, necessitating remediation plans and protection policies to prevent overexploitation and brook the VSC. Finally, the integration of the adopted approaches was found useful, constraining the findings of one approach, reducing the associated uncertainties, enhancing the confidence level and reliability of the obtained conclusions, and obtaining useful information, enabling understanding of the internally interacting processes otherwise hidden.

Drawing development plans requires evaluating the available resources and assessing their sustainable and subsequent utilization-driven environmental impacts. The current work is concerned with evaluating the sustainability of the halite harvesting process from Al-Qasab Playa, Shaqra, Central Saudi Arabia. The authors integrated, conceptually and quantitatively, ArcGIS-processed SRTM-DEM (Shuttle Radar Topography Mission-Digital Elevation Model) data, hydrogeochemical and thermodynamic-based geochemical modelling, and graphical approaches to achieve the ultimate aims of the study. The watershed is identified as a nonmarine closed basin with a drainage area of 1290 km², with the slope controlling recharge to the Playa. The Chadha plot including the rainwater exhibits linear regression, with an R² value of 0.9947, confirming the rainwater origin of the Playa water. The hardness-forming ions are primarily removed in pond 3, eliminating the need for costly and power-consuming steps of softening with ion exchange resins or nanofiltration as it can be used directly as a readily available feed for the chlor-alkali process for producing NaOH, Cl₂, and H₂ gases through electrolysis. XRD (X-ray diffraction) analysis and the SEM-EDS (Scanning electron microscopy-energy dispersive X-ray spectroscopy) of the harvested halite confirmed its purity. An improved design of the current folkloric harvesting process has been proposed based on the saturation indices calculated thermodynamically to provide a readily available feed intake for the electrolysis chlor-alkali process with or without minimal pretreatment to produce higher value chemicals. The methodological aspects presented here are deemed robust and valid for applications in other study areas, including the assessment of the exploitation of the rejected brine from the desalination plants to achieve the zero liquid discharge approach, as well as other types of sabkhas, regardless of their geographical location.