University of Bouira

The escalating threat of antimicrobial resistance (AMR) and the environmental impact of industrial pollutants, particularly synthetic dyes, emphasize the pressing requirement for novel solutions. This study investigates the green synthesis of ZnO/Fe2O3 nanocomposites using Urtica dioica extract with the aim of achieving dual functionality as both antimicrobial agents and photocatalysts for pollutant degradation. The nanocomposites were synthesized with varying loads of Fe2O3 (5-50%) and characterized using X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS). XRD analysis confirmed the presence of both the hexagonal wurtzite ZnO phase and the alpha-Fe2O3 hematite phase in all the composites, while DRS analysis revealed that the bandgap energy decreased progressively (from 1.89 to 1.72 eV) as the Fe2O3 content increased. The photocatalytic efficiency of the composites was evaluated by degrading methylene blue (MB), Congo Red (CR) and safranin O (SO) dyes under visible light. This demonstrated that the degradation performance depends on the composition, with the best activity being observed at 5% Fe2O3. Antioxidant activity was assessed using a DPPH center dot free radical scavenging assay. This showed that Urtica dioica extract exhibits superior radical scavenging capacity (maximum inhibition of 38%) compared to ZnO/Fe2O3 nanoparticles (maximum inhibition of 18%). The antibacterial efficacy against Pseudomonas aeruginosa was evaluated using direct confrontation and disk diffusion methods. This revealed that the activity was dose- and light-dependent, with enhanced performance under light exposure (10 mm inhibition zone) compared to dark conditions (1 mm). This study demonstrates the successful green synthesis of biphasic ZnO/Fe2O3 nanocomposites with promising photocatalytic and antimicrobial properties. While the results suggest possible synergistic interactions between the oxides, the underlying mechanisms, including potential charge transfer effects, require further investigation using advanced characterization techniques. Using Urtica dioica extract as a biogenic source provides a promising eco-friendly approach to synthesizing nanomaterials, with potential applications in wastewater treatment and the biomedical field.

Sulfamethazine (SMZ) has become a widespread pollutant in aquatic environments, posing serious ecological risks and contributing to the development of antimicrobial resistance. Conventional water treatment techniques are generally inefficient at eliminating such pharmaceuticals; however, adsorption using polymeric resins offers a promising alternative. This study investigates the removal of SMZ using a strong acid cation-exchange resin (Purolite C100E). Batch experiments were conducted to examine the influence of key operational parameters, including pH, contact time, resin dosage, temperature, stirring speed, exchangeable cation form, and the presence of a co-adsorbate. Equilibrium isotherm experiments were performed using initial SMZ concentrations in the range of 20-280 mg/L. Operating conditions (pH 5, resin dosage 1 g/L, and contact time 150 min) were selected to achieve high removal efficiency, while the intrinsic adsorption performance of the resin was evaluated using equilibrium isotherms. The adsorption data were best described by the Langmuir model, yielding a high maximum adsorption capacity (qm) of 338.92 +/- 21.46 mg/g, which is superior to many previously reported adsorbents. Kinetic studies showed good agreement with the pseudo-second-order model, and thermodynamic analysis confirmed that the adsorption process is spontaneous and exothermic. FTIR analysis indicated that SMZ adsorption is mainly governed by hydrogen bonding and pi-pi interactions rather than electrostatic attraction. The resin exhibited good reusability over three adsorption-desorption cycles, and competitive adsorption tests demonstrated high selectivity toward SMZ. These results indicate that Purolite C100E is an efficient, selective, and reusable adsorbent for the removal of sulfonamide antibiotics from contaminated water.

Liquid potassium is a prime candidate for fusion reactor cooling due to its excellent thermal properties and high electrical conductivity. However, its magnetohydrodynamic behavior under strong magnetic fields is significantly influenced by wall electrical conductivity, a factor often oversimplified in previous studies. This work presents a three-dimensional numerical analysis using the finite volume method to systematically quantify the impact of three electrical boundary configurations on heat transfer and fluid dynamics in a potassium-filled vertical annulus subjected to a radial magnetic field: fully insulated walls (EI), conductive inner/outer walls (EC-Inner/Outer), and conductive top/bottom walls (EC-Top/Bottom). Results demonstrate a non-monotonic dependence of heat transfer on geometry. Increasing the annular gap ratio (R) consistently enhances the Nusselt number, while an optimal aspect ratio (A) near unity is observed, beyond which thermal stratification degrades performance. A regime-dependent optimal configuration is identified: for intermediate gaps (0.5 <= R <= 0.85) under strong magnetic fields (Ha = 80), the EC-Top/Bottom configuration mitigates Lorentz damping, enhancing heat transfer by 5%-10%. For wider gaps (R > 0.85), fully insulated walls become optimal. This performance inversion arises from current path reconfiguration by conductive walls, which weakens the bulk induced electric field by up to 32% and fundamentally restructures the Hartmann and Roberts boundary layers.

The Saoura Valley (southwestern Algeria) hosts14 oases that primarily depend on groundwater in an endorheic basin. The hydrogeological system is bisected by the Saoura Wadi into two distinct compartments: an active, interconnected eastern compartment (Mio-Plio-Quaternary alluvial aquifer and terraces of the Great Western Erg) and a passive, fossil western compartment (Guir Hamada and Cambro-Ordovician aquifers). In September 2024, 51 groundwater samples were collected from nine oases. Temperature ranged from 16.2 to 31.4 degrees C and pH ranged from 7.1 to 7.85. Total dissolved solids (TDS) varied widely (179-4480 mg/L; median of 454 mg/L), with electrical conductivity between 280 and 7000 & micro;S/cm. Three main hydrochemical facies were identified: Ca-Mg-SO4-Cl (30%), Na-Cl-SO4 (55%), and hypersaline types in the terminal inferoflux zone. Nitrate concentrations exceeded the WHO guideline (50 mg/L) in 22% of samples, attributed to localized agricultural and domestic inputs. Geochemical evolution is controlled by evaporite dissolution (gypsum, halite), cation exchange, and evaporative concentration, with a downstream salinity gradient from freshwaters near the Great Western Erg toward hypersaline inferoflux. Comparison with historical data (1941, 1963, and earlier studies) indicates a trend of increasing salinization since the 1990s, associated with intensive borehole pumping and irrigation return flow. These findings suggest risks to the long-term sustainability of the Saoura oases.

Municipal sewage sludge is an environmental liability but also an energy-rich biomass that can support circular economy resource recovery. Here, we benchmark thin-layer drying of dewatered municipal sewage sludge (sludge cake) (40 g; layer thickness <= 5 mm) under open-air, convective hot air (40-150 degrees C), and microwave (70-1200 W) conditions to quantify drying kinetics, hygienisation indicators, and a screening-level energy-use proxy. High-power microwave drying reduced the time to constant mass from 32 h (open air) and 25 h 05 min (40 degrees C convection) to 20 min (900 W) and 14 min 05 s (1200 W). Faecal indicators (total/thermotolerant coliforms and presumptive Escherichia coli) were below detection after >= 100 degrees C convection or >= 300 W microwave treatment, while mesophilic aerobes and sulfite-reducing Clostridium spp. decreased by similar to 3-4 log10 with increasing exposure. A dragonfly-optimised epsilon-support vector regression model (DA-SVR) predicted drying trajectories across modes (overall RMSE approximate to 0.79 percentage points; held-out RMSE approximate to 1.47; R-2 >= 0.99). Overall, microwave thin-layer drying coupled with DA-SVR decision support enables constraint-based screening of sewage-sludge conditioning windows for logistics and thermal valorisation pathways; the framework can be extended to incorporate additional analytical endpoints where available.