Foziah F. Al-Fawzan

For the successful production of NiO/NiCo₂O₄ nanocomposites, the environmentally friendly method of egg white supplementation has been used. Several analytical techniques were employed to characterize the morphology, purity, and crystal structure of the as-prepared nanocomposites. These techniques included transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The physical adsorption and magnetic properties of the investigated composite were determined using the Brunauer–Emmett–Teller (BET) method and a vibrating-sample magnetometer (VSM), respectively. The results have shown that the as-prepared composite particles had diameters of about 10–25 nm, with uniform distribution. The XRD analysis showed that the as-synthesized composites consisted entirely of cubic structures of both NiO and spinel NiCo₂O₄ nanoparticles, with a space group of Fd3m. The FTIR analysis showed characteristic vibration modes related to metal oxides, confirming the formation of composites containing NiO and NiCo₂O₄ crystallites. The investigated composites’ saturation magnetization (M_S) and coercivity (H_C) were easily controllable because of the ingredients’ ferromagnetic (NiCo₂O₄) and antiferromagnetic (NiO) characteristics. The excellent combination of the NiO/NiCo₂O₄ nanocomposites’ properties is anticipated to make this system suitable for a wide range of applications.

An entirely novel and creative technique was employed for producing magnetic Ni–NiO@C nanocomposites, and it was based on the utilization different amounts of finely ground and fully dried olive leaf powders. The resulting nanocomposites were identified and characterized by XRD, FTIR, SEM, EDS, TEM, and Raman techniques. The magnetic and surface characteristics of the composites, as it developed, were further evaluated using the Vibrating-Sample Magnetometer (VSM) and Brunauer–Emmett–Teller (BET) techniques. The results confirmed the success of preparing a Ni–NiO@C nanocomposites, each containing Ni and NiO in crystalline form. Through the morphology of the resulting composites, determined on the basis of an SEM analysis, it became clear to us that the particles were of a semi-spherical shape, with a clear grouping and a definition of their grain boundaries. Comparably, a TEM investigation demonstrated that the composites had a core–shell structure. The surface area of the investigated composites increases as the content of dried olive leaf powders increases due to a significant increase in the total pore volume. These composites illustrated low magnetism (4.874 and 8.648 emu/g) and coercivity (55.203 and 39.639 Oe) for a number of reasons, which will be explained.

Two extremophilic cyanobacterial-bacterial consortiums naturally grow in extreme habitats of high temperature and hypersaline were used to remediate hexavalent chromium and molybdenum ions. Extremophilic cyanobacterial-bacterial biomasses were collected from Zeiton and Aghormi Lakes in the Western Desert, Egypt, and were applied as novel and promising natural adsorbents for hexavalent chromium and molybdenum. Some physical characterizations of biosorbent surfaces were described using scanning electron microscope, energy-dispersive X-ray spectroscopy, Fourier transformation infrared spectroscopy, and surface area measure. The maximum removal efficiencies of both biosorbents were 15.62-22.72 mg/g for Cr(VI) and 42.15-46.29 mg/g for Mo(VI) at optimum conditions of pH 5, adsorbent biomass of 2.5-3.0 g/L, and 150 min contact time. Langmuir and Freundlich adsorption models were better fit for Cr(VI), whereas Langmuir model was better fit than the Freundlich model for Mo(VI) biosorption. The kinetic results revealed that the adsorption reaction obeyed the pseudo-second-order model confirming a chemisorption interaction between microbial films and the adsorbed metals. Zeiton biomass exhibited a relatively higher affinity for removing Cr(VI) than Aghormi biomass but a lower affinity for Mo(VI) removal. The results showed that these extremophiles are novel and promising candidates for toxic metal remediation.

Water treatment through photocatalysts has become an important topic regarding environmental protection. In the present study, silver and TiO₂ (Ag/TiO₂) composites for photocatalysts were effectively synthesized by adopting the template induced method. The prepared samples were characterized using XRD, FTIR spectroscopy, SEM, and EDX. The constructed samples’ particle size and shape were evaluated using a SEM, and the XRD patterns showed anatase crystalline phases. Their morphologies were controllable with changing concentration of reactants and calcination temperature. The synthesized composites act as catalyst in the degradation of methylene blue (MB) and reduction of Cr(VI) to Cr(III) under solar irradiation. In both of these activities, the best result has been shown by the 0.01 Ag/TiO₂ composite. Methanol is used as the hole scavenger in the reduction of Cr(VI) to Cr(III). While the pH factor is important in the photocatalytic reduction of Cr(VI) to Cr(III). According to observations, S. macrospora and S. maydis were each subject to 0.01 Ag/TiO₂ nanocomposites maximum antifungal activity, which was 38.4 mm and 34.3 mm, respectively. The outcomes demonstrate that both photocatalytic and antifungal properties are effectively displayed by the constructed material.

Heterojunctions have proven to be effective catalysts for removing organic pollutants and heavy metals from wastewater. The following study is also about the formation of 2D heterojunction tellurium-doped zinc oxide composite with sulfur-doped graphitic carbon nitride (Te-ZnO@S-g-C₃N₄) by adopting a low-cost, simple, and ecofriendly coprecipitation technique. Thiourea was calcined to prepare S-g-C₃N₄ using the thermal degradation method. The characterization of synthesized photocatalysts was carried out by using SEM-EDX, FTIR, and XRD. The results obtained showed that the incorporation of tellurium caused an alteration in the wurtzite structure of ZnO. SEM-EDX analysis validated the purity of the synthesized samples due to the absence of any additional peaks. The decrease in the bandgap was also noted by the formation of composites. Using methylene blue as a reference dye, the UV-vis spectrophotometer was utilized to calculate the absorbance for photocatalytic degradation behavior. As a result of tellurium doping into the ZnO lattice, photocatalytic oxidation/reduction was improved, according to the results. 3Te-ZnO NPs showed the best degradation rate among dopant series, while an excellent overall degradation rate was noted by fabricated composite 3Te-ZnO@40S-g-C₃N₄. The best doped ZnO and composites were also used as sorbents for the abstraction of heavy metal (Cr(VI)) from water via adsorption. A definite rise in the removal efficiency percentage of chromium ions was observed by using these sorbents. The overall photo degradation rate and adsorption behavior noted were in ZnO3N₄ order. When compared to ZnO, Te-ZnO, SCN, and Te-ZnO@40SCN, the 3Te-ZnO@40SCN NCs have outstanding antifungal potential. The improved dispersibility and interaction of 3Te-ZnO@40SCN with membrane and intracellular proteins of fungi may be the cause of the greater effect of Te-ZnO@40SCN.

The pollution due to dyes from textile sector is one of the major issues faced worldwide. This study was focused on the removal of the reactive dye, Drimaren Turquoise CL-B using Schizophyllum commune, a white rot fungus (WRF) keeping in mind the current environmental conditions. Different parameters like pH, sources of carbon & nitrogen, temperature, concentration of dye and C/N ratio were used to investigate their effect on the process. Maximum dye removal of 95.45% was obtained at pH 4.5, temperature 35°C, inoculum size 3 mL, veratryl alcohol (mediator), glucose (carbon source) and ammonium nitrate (nitrogen source). The enzyme activity was determined by employing enzyme assay. Laccase and Lignin peroxidase (LiP) activity was low while Manganese peroxidase (MnP) activity was highest. Maximum bio-sorption was achieved at pH 1 and 313 K. The pseudo-2^nd-order kinetic model & Freundlich isotherm was best suited for the process of removal of dye. From these data, it is concluded that white rot fungus could possibly be the excellent biomaterial for elimination of synthetic dyes from wastewater.

A series of virgin and lithia-doped Ni ferrites was synthesized using egg-white-mediated combustion. Characterization of the investigated ferrites was performed using several techniques, specifically, X-ray Powder Diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and High-resolution transmission electron microscopy (HRTEM). XRD-based structural parameters were determined. A closer look at these characteristics reveals that lithia doping enhanced the nickel ferrite lattice constant (a), unit cell volume (V), stress (ε), microstrain (σ), and dislocation density (δ). It also enhanced the separation between magnetic ions (L_A and L_B), ionic radii (r_A, r_B), and bond lengths (A-O and B-O) between tetrahedral (A) and octahedral (B) locations. Furthermore, it enhanced the X-ray density (Dx) and crystallite size (d) of random spinel nickel ferrite displaying opposing patterns of behavior. FTIR-based functional groups of random spinel nickel ferrite were determined. HRTEM-based morphological properties of the synthesized ferrite were investigated. These characteristics of NiFe₂O₄ particles, such as their size, shape, and crystallinity, demonstrate that these manufactured particles are present at the nanoscale and that lithia doping caused shape modification of the particles. Additionally, the prepared ferrite’s surface area and total pore volume marginally increased after being treated with lithia, depending on the visibility of the grain boundaries. Last, but not least, as the dopant content was increased through a variety of methods, the magnetization of virgin nickel ferrite fell with a corresponding increase in coercivity. Uniaxial anisotropy, rather than cubic anisotropy, and antisite and cation excess defects developed in virgin and lithia-doped nickel ferrites because the squareness ratio (M_r/M_s) was less than 0.5. Small squareness values strongly recommend using the assessed ferrites in high-frequency applications.

In this study, cobalt oxide (Co₃O₄), Mn-doped Co₃O₄ (MDCO), and Mn-doped Co₃O₄-functionalized carbon nanotube (MDCO-CNTs) were synthesized via the co-precipitation method using cobalt nitrate and manganese nitrate as a cobalt and manganese precursor, respectively. Synthesized materials were assessed using different characterization techniques like scanning electron microscopy, X-ray diffraction, and UV-visible spectroscopy. Congo red in an aqueous solution was adopted as the model dye to estimate the adsorption-assisted photocatalytic efficiency of the synthesized materials. The samples studied for adsorpsstion-assisted photocatalysis were found to be highly effective and among all the samples, the best removal performance (80%) was obtained by treating the MDCO-CNTs composite for 50 min at 50 °C. Mathematical modeling shows that all of the samples followed a pseudo-second-order kinetic model and data best fitted to a Langmuir isotherm, implying that the process involved in the removal of Congo red dye is chemisorption.