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Toxic metals in water systems pose a global health risk. Thus, multifunctional water monitoring and treatment materials are indispensable. Nickel ions, a frequent heavy metal pollutant, affect ecosystem function. However, developing affordable, functional materials for efficient heavy metal removal remains problematic. This study investigates the utilization of Al2O3@g-C3N4 (AlCN) nanosorbent for adsorbing Ni (II) ions from aqueous solutions. The physicochemical analyses verify the creation of an AlCN nanosorbent with a mean size of 31.25 nm crystals and a specific surface area of 58 m2/g. Batch adsorption experiments were conducted to examine the impact of pH, initial Ni (II) concentration, and adsorbent dose on the efficiency of Ni (II) removal using the synthesized (AlCN) nanosorbent. Adding Al2O3 to g-C3N4 nanosheets increased the adsorption capacity to a maximum of 410 mg/g under ideal conditions, as demonstrated by the results. Ni (II) ions adsorption kinetics on AlCN nanosorbents follow the pseudo-second-order kinetic model with an R2 value of 0.99, surpassing the Elovich pseudo-first model. The adsorption isotherm results show that the Langmuir model fits the experimental data better than the Freundlich and Temkin models, indicating a monolayer adsorption process for the AlCN nanosorbent. In addition, the AlCN exhibited multi-elemental adsorption ability and good recyclability. These findings can nominate the fabricated composite as a candidate for water treatment.

The aqueous onion peel extract (OPE) was used to synthesize silver nanoparticles (Ag-onion), samarium oxide nanoparticles (Sm2O3-onion), and silver/samarium oxide core/shell nanoparticles (Ag@Sm2O3-onion). The produced nanoparticles were characterized by thermal gravimetric analysis (TGA), infrared spectra (FT-IR), absorption spectra (UV–Vis), energy band gap, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), zeta potential, and transmission electron microscopy (TEM). OPE and NPs were tested for the disinfection of some water microbes. XRD analysis exhibited an amorphous structure of samarium oxide in both Sm2O3-onion and Ag@ Sm2O3-onion. The isolated bacteria from the water sample were Bacillus subtilis (OQ073500) and Escherichia coli (MW534699), while the isolated fungi were Alternaria brassicae (MZ266540), Aspergillus flavus (MT550030), Aspergillus penicillioides (MW957971), Pythium ultimum (MW830915), Verticillium dahlia (MW830379), Fusarium acuminatum (MZ266538), Candida albicans (MW534712), and Candida parapsilosis (MW960416). High levels of antimicrobial activity were seen in both the nanoparticles and the aqueous onion peel extract. Based on experimental results, Ag@Sm2O3 demonstrated the highest activity as an effective disinfectant, indicating the effectiveness of the modification process.

The sustainable plant-derived biomass are now understood to be important sources for the prevention of corrosion in metallic alloys. This study examined the effect of a potential novel low-cost, low-toxicity inhibitor utilizing pumpkin peel extract (PPE) on aluminum corrosion hydrochloric acid 1M HCl medium. Several experimental methods were used to investigate the inhibitor effect of PPE which include, AFM-XPS surface analysis, electrochemical studies (electrochemical impedance spectroscopy-electrochemical frequency modulation-potentiodynamics), and weight loss procedures. According to the weight loss results, when PPE is introduced to a 1M HCl solution, the inhibitory performance rises up to 95.42% with an increase in PPE concentration in the range of 0–300 ppm at 25°C. Potentiodynamic results showed the investigated PPE inhibitor is a mixed-type inhibitor. Corrosion inhibition at different temperatures was also examined, and the thermodynamic activation parameters were identified. It was found that the adsorption of the inhibitor on the aluminum followed the Langmuir and kinetic isotherm models. Quantum chemical indices contributed to a greater comprehension of the inhibitory mechanism. To investigate the configurational adsorption performance of the investigated PPE on the aluminum surface, molecular dynamics (MD) simulations were carried out.

The purification and densification of wastewater play an important role in water recycling, especially if the materials used in water recycling are other types of recycled waste. Therefore, considering this view in this study, the biosynthesis of silver-decorated chromium oxide nanoparticles utilizing a wasted Allium sativum (garlic) peel extract is investigated. The aqueous extract of garlic peel (GPE) was treated with silver nitrate, chromium nitrate, and a mixture of silver nitrate and chromium nitrate to synthesize silver nanoparticles (Ag-garlic), chromium oxide nanoparticles (Cr2O3-garlic), and silver-decorated chromium oxide nanoparticles (Ag@Cr2O3-garlic), respectively. The synthesized nanoparticles were elucidated via thermal gravimetric analysis (TGA), infrared spectra (FT-IR), absorption spectra (UV-Vis), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Antimicrobial activity studies were conducted against waterborne germs, bacterial strains (Bacillus subtilis, Enterococcus faecium, Escherichia coli, and Pseudomonas aeruginosa), and fungal strains (Alternaria porri, Aspergillus flavus, Aspergillus niger, Fuserium oxysporum, and Trichoderma longibrachiatum) and showed significant levels of antimicrobial activity. The results revealed that Ag@Cr2O3 significantly improved antimicrobial activity due to their synergistic effect. The photocatalytic activity of nanoparticles was assessed using Rhodamine B dye (5 ppm) under solar irradiation. Cr2O3-garlic exhibited the best activity as a photocatalyst among the studied nanoparticles, with 97.5% degradation efficiency under optimal conditions.

In the last decades, the idea of green nanotechnology has been expanding, and researchers are developing greener and more sustainable techniques for synthesizing nanoparticles (NPs). The major objectives are to fabricate NPs using simple, sustainable, and cost-effective procedures while avoiding the use of hazardous materials that are usually utilized as reducing or capping agents. Many biosources, including plants, bacteria, fungus, yeasts, and algae, have been used to fabricate NPs of various shapes and sizes. The authors of this study emphasized the most current studies for fabricating NPs from biosources and their applications in a wide range of fields. This review addressed studies that cover green techniques for synthesizing nanoparticles of Ag, Au, ZnO, CuO, Co3O4, Fe3O4, TiO2, NiO, Al2O3, Cr2O3, Sm2O3, CeO2, La2O3, and Y2O3. Also, their applications were taken under consideration and discussed.