Metal Oxides Nanoparticles: General Structural Description, Chemical, Physical, and Biological Synthesis Methods, Role in Pesticides and Heavy Metal Removal through Wastewater Treatment

Nanotechnology (NT) is now firmly established in both the private home and commercial markets. Due to its unique properties, NT has been fully applied within multiple sectors like pharmacy and medicine, as well as industries like chemical, electrical, food manufacturing, and military, besides other economic sectors. With the growing demand for environmental resources from an ever-growing world population, NT application is a very advanced new area in the environmental sector and offers several advantages. A novel template synthesis approach is being used for the promising metal oxide nanostructures preparation. Synthesis of template-assisted nanomaterials promotes a greener and more promising protocol compared to traditional synthesis methods such as sol-gel and hydrothermal synthesis, and endows products with desirable properties and applications. It provides a comprehensive general view of current developments in the areas of drinking water treatment, wastewater treatment, agriculture, and remediation. In the field of wastewater treatment, we focus on the adsorption of heavy metals and persistent substances and the improved photocatalytic decomposition of the most common wastewater pollutants. The drinking water treatment section covers enhanced pathogen disinfection and heavy metal removal, point-of-use treatment, and organic removal applications, including the latest advances in pesticide removal

The Influence of the Calcination Time on Synthesis of Nanomaterials with Small Size, High Crystalline Nature and Photocatalytic Activity in the TiO₂ Nanoparticles Calcined at 500 °C

The development of new materials with diverse applications that fit well in the context of the current economy, where energy issues abound, is paramount. The goal of this study was to generate materials with high photocatalytic properties, at low cost and with less energy, and without health and ecological risks. Such materials would allow for a form of sustainable development that respects nature. This study investigated the influence of calcination time on titanium dioxide nanoparticles (TiO2 NPs) produced by green synthesis using Aloe vera leaf extract under a constant temperature of 500 °C. The interaction between synthesis conditions like calcination time and the size of nanoparticles produced in relation to changes in photocatalytic activity were analyzed and discussed. The results showed that when calcination was increased at 500 °C, the synthesis of small-diameter nanoparticles was promoted. TiO2 were 23 ± 2 nm (D1) and 83 ± 5 nm (D2) after 5 h and 1 h of calcination, respectively. Moreover, the calcination duration promoted an increase in crystalline nature. In the same way, the level of reduction of azo dye Remazol Red Brilliant F3B (RR180) increased when calcination time increased, and therefore, changed the optic and photo-catalytic properties of the TiO2 nanomaterial. In addition, TiO2 nanopowders (size 23 ± 2 nm) had the higher efficiency in photodegradation (100%) of dye RR180 under visible light irradiation for 60 min for up to one hour duration, but TiO2 NPs (83 ± 5 nm) had the higher efficiency (100%) for up to two hours duration

The Influence of the Calcination Time on Synthesis of Nanomaterials with Small Size, High Crystalline Nature and Photocatalytic Activity in the TiO2 Nanoparticles Calcined at 500 °C

The development of new materials with diverse applications that fit well in the context of the current economy, where energy issues abound, is paramount. The goal of this study was to generate materials with high photocatalytic properties, at low cost and with less energy, and without health and ecological risks. Such materials would allow for a form of sustainable development that respects nature. This study investigated the influence of calcination time on titanium dioxide nanoparticles (TiO2 NPs) produced by green synthesis using Aloe vera leaf extract under a constant temperature of 500 °C. The interaction between synthesis conditions like calcination time and the size of nanoparticles produced in relation to changes in photocatalytic activity were analyzed and discussed. The results showed that when calcination was increased at 500 °C, the synthesis of small-diameter nanoparticles was promoted. TiO2 were 23 ± 2 nm (D1) and 83 ± 5 nm (D2) after 5 h and 1 h of calcination, respectively. Moreover, the calcination duration promoted an increase in crystalline nature. In the same way, the level of reduction of azo dye Remazol Red Brilliant F3B (RR180) increased when calcination time increased, and therefore, changed the optic and photo-catalytic properties of the TiO2 nanomaterial. In addition, TiO2 nanopowders (size 23 ± 2 nm) had the higher efficiency in photodegradation (100%) of dye RR180 under visible light irradiation for 60 min for up to one hour duration, but TiO2 NPs (83 ± 5 nm) had the higher efficiency (100%) for up to two hours duration

The effect of chemical dispersant of the third generation (Finasol OSR 62) on the microbial biodegradation process of Zarzaitine oil in water treatment

International audienceThe application of chemical dispersants aims to stimulate microbial oil degradation by increasing the bioavailability of oil compounds. Overall, nine microcosms were prepared (three for each treatment) using treated sediment with (i) dispersant (d: 25 ppm), (ii) oil (500 ppm), and (iii) with oil + dispersant (500: 25 ppm), respectively. There are also three control microcosms containing only water and sediment without petroleum. Then, we analyzed bacterial abundance, total hydrocarbon, biological oxygen demand (BOD5), and chemical oxygen demand (COD) in each microcosm. Bacterial response density was significantly affected after 40 days of exposure; it was higher in the control microcosm and d (> 24.103 cell/l) than in the other treatments. The index of total hydrocarbons was equal to 53 mg/kg dw in oil and 56 mg/kg dw in oil + dispersant. The higher BOD5 found in oil and in oil + d shows the increased amount of oxygen consumed, which indicates enhanced bacterial activity. Microcosms treated with dispersant had higher COD than the others, but the dispersant did not stimulate microbial hydrocarbon degradation

Use of gas chromatography-mass spectrometry techniques (GC-MS, GC-MS/MS and GC-QTOF) for the characterization of lipid photooxidation and autoxidation products in senescent autotrophic organisms

International audienceThis paper reviews applications of gas chromatography-mass spectrometry techniques for the characterization of lipid photooxidation and autoxidation products in senescent phototrophic organisms. Particular attention is given to: (i) the selection of oxidation products that are sufficiently stable and specific to each lipid class and degradation route, (ii) the description of electron ionization mass fragmentation of trimethylsilyl derivatives of these compounds and (iii) the use of specific fragment ions for monitoring the oxidation of the main unsaturated lipid components of phototrophs. The techniques best geared for this task were gas chromatography-quadrupole-time of flight to monitor fragment ions with very high resolution and accuracy, and gas chromatography-tandem mass spectrometry to monitor very selective transitions in multiple reaction monitoring mode. The extent of the degradation processes can only be estimated if the oxidation products are unaffected by fast secondary oxidation reactions, as it is notably the case of 5-sterols, monounsaturated fatty acids, chlorophyll phytyl side-chain, and di-and triterpenoids. In contrast, the primary degradation products of highly branched isoprenoid alkenes possessing more than one trisubstituted double bond, alkenones, carotenoids and polyunsaturated fatty acids, appear to be too unstable with respect to secondary oxidation or other reactions to serve for quantification in senescent phototrophs

Influence of Cedar Essential Oil on Physical and Biological Properties of Hemostatic, Antibacterial, and Antioxidant Polyvinyl Alcohol/Cedar Oil/Kaolin Composite Hydrogels

Polyvinyl alcohol (PVA) is a safe and biodegradable polymer. Given the unique physical and chemical properties of PVA, we physically cross-linked PVA with kaolin (K) and cedar essential oil (Ced) using the freeze-thawing approach to fabricate PVA/Ced/K sponge hydrogels as hemostatic, antibacterial, and antioxidant wound healing materials. The physicochemical characteristics of PVA/Ced/K hydrogels, including water swelling profiles and gel fractions, were surveyed. Additionally, the functional groups of hydrogels were explored by Fourier transform infrared spectroscopy (FTIR), while their microstructures were studied using scanning electron microscopy (SEM). Furthermore, the thermal features of the hydrogels were probed by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Evidently, alterations in cedar concentrations resulted in significant variations in size, water uptake profiles, and hydrolytic degradation of the hydrogels. The incorporation of cedar into the PVA/K endowed the hydrogels with significantly improved antibacterial competency against Bacillus cereus (B. cereus) and Escherichia coli (E. coli). Moreover, PVA/Ced/K exhibited high scavenging capacities toward ABTS•+ and DPPH free radicals. Beyond that, PVA/Ced/K hydrogels demonstrated hemocompatibility and fast blood clotting performance in addition to biocompatibility toward fibroblasts. These findings accentuate the prospective implementation of PVA/Ced/K composite hydrogel as a wound dressing