Electrospun Polymer-Inorganic Nanostructured Materials and Their Applications

Nd-Doped ZnO Nanostructures with Enhanced Photocatalytic Performance for Environmental Protection

Neodymium (Nd)-doped ZnO nanostructures with different amounts of Nd were obtained by the electrospinning-calcination method. X-ray diffraction measurements indicated that the prepared nanostructures have a wurtzite structure without undesirable impurities. Nd doping changes the mean crystallite size as well the lattice strain, as proved by Williamson-Hall plots. The ZnO-based nanostructures were tested as photocatalysts for methylene blue (MB) dye and ciprofloxacin (CIP) drug pollutant degradations under visible light irradiation. Corroborating the obtained results, it was found that the reaction rate constant increased almost linearly with the mean crystallite size (from 2.235 × 10^-2 to 3.482 × 10^-2 min^-1) with a variation in the mean crystallite size from 24.2 to 42.1 nm. Furthermore, the best catalyst sample (0.1% Nd-doped ZnO) was used to optimize the photodegradation process of ciprofloxacin, taking into account the pollutant concentration as well as the catalyst dose. The removal efficiency after 120 min was about 100%, with the rate constant of k = 5.291·10^-2 min^-1 (CIP) and k = 4.780·10^-2 min^-1 (MB) for the established optimal conditions. Considering the value of the rate constant, the half-life of the reaction (τ_1/2 = ln2/k) was evaluated to be about τ_1/2 =13 min for CIP and 14.5 min corresponding to MB. Several catalytic cycles were successfully performed without any loss of photocatalytic activity using these nanostructures, demonstrating that the obtained nanostructures have good stability in the leaching processes.

Ofloxacin Removal from Aqueous Media by Means of Magnetoactive Electrospun Fibrous Adsorbents

Functionalized electrospun polymer microfibrous membranes were fabricated by electrospinning and further surface-functionalized with magnetic iron oxide (Fe_xO_y) nanoparticles to yield magnetoactive nanocomposite fibrous adsorbents. The latter were characterized in respect to their morphology, mechanical properties and magnetic properties while they were further evaluated as substrates for removing Ofloxacin (OFL) from synthetic aqueous media and secondary urban wastewater (UWW) under varying physicochemical parameters, including the concentration of the pharmaceutical pollutant, the solution pH and the membranes' magnetic content. The magnetic-functionalized fibrous adsorbents demonstrated significantly enhanced adsorption efficacy in comparison to their non-functionalized fibrous analogues while their magnetic properties enabled their magnetic recovery and regeneration.

A Study on the Applicability of NiFe2O4 Nanoparticles as the Basis of Catalysts for the Purification of Aqueous Media from Pollutants

The aim of this work is to evaluate the application of NiFe2O4 nanoparticles with spinel structures as the basis of catalysts for the purification of aqueous media from pollutants such as manganese and arsenic. The interest in these catalysts is due to their ease of production and high absorption efficiency, which, together with their magnetic properties, allow the use of nanoparticles for a long time. The sol–gel method, followed by thermal annealing of the samples at different temperatures, was proposed as a method for the synthesis of spinel nanoparticles. The choice of the annealing temperature range of 200–1000 °C is caused by the possibility of estimating changes in the structural properties and the degree of nanoparticles crystallinity. During the study of structural changes in nanoparticles depending on the annealing temperature, it was found that in the temperature range of 200–800 °C, there is an ordering of structural parameters, while for samples obtained at annealing temperatures above 800 °C, there is a partial disorder caused by the agglomeration of nanoparticles with a subsequent increase in their size. According to the results of the studies on the purification of aqueous media from pollutants, it was found that the greatest absorption efficiency belongs to nanoparticles annealed at 500–700 °C, with the purification efficiency of 70–85%, depending on the type of pollutant. The results obtained from the use of nanoparticles as catalysts for the purification of aqueous media show great prospects for their further application on an industrial scale.

Photocatalytic-Fenton Process under Simulated Solar Radiation Promoted by a Suitable Catalyst Selection

Considering water scarcity, photo-based processes have been presented as a depollution technique, which should be optimized in order to be applied in the future. For that, the addition of an active photocatalyst and the usage of solar radiation are mandatory steps. Thus, Fe3O4–SiO2–TiO2 was synthesized, and its performance was evaluated using simulated solar radiation and methylene blue as a model pollutant. Under optimal conditions, 86% degradation was attained in 1 h. These results were compared to recent published data, and the better performance can be attributed to both the operational conditions selection and the higher photocatalyst activity. Indeed, Fe3O4–SiO2–TiO2 was physico-chemically characterized with techniques such as XRD, N2 isotherms, spectrophotometry, FTIR, electrochemical assays and TEM.

Hierarchical Structured Polyimide-Silica Hybrid Nano/Microfiber Filters Welded by Solvent Vapor for Air Filtration

Electrospun polymer membranes were considered to be promising materials for fine particulate matter (PM) filtration. However, the poor mechanical properties of the electrospun membrane restricted their application for pressure-driven air filtration. Herein, strength-enhanced electrospun polyimide (PI) membranes were demonstrated via a synergistic approach. Solvent-vapor treatment was utilized to introduce extra bonding at the cross points of PI nanofiber, while SiO₂ nanoparticles (SiO₂ NPs) were used to reinforce the body of nanofibers. The mechanical strength and filtration performance of hybrid membranes could be regulated by adjusting the quantity of SiO₂ NPs. The tensile strength of the pure PI membrane was increased by 33% via adding 1.5% SiO₂ NPs, which was further promoted by 70% after solvent-vapor treatment. With a slight reduction in pressure drop (6.5%), the filtration efficiency was not greatly suppressed by welding the SiO₂ NP hybrid PI nanofibers. Moreover, the welded composite filter showed high particulate (0.3–1.0 μm) filtration efficiency (up to nearly 100%) and stable pressure drop throughout the 20 tested filtration cycles.

Application of electrospinning technique in development of intelligent food packaging: A short review of recent trends

Intelligent food packaging refers to packages with the ability to sense foodstuff changes and to inform customers of the packaging content variations. They are often accompanied by smart detecting devices. Providing a suitable platform to include these devices into packaging polymers has always been discussing. Electrospun nanofibers produced through the electrospinning have been recently utilized as an outstanding and novel platforms for this purpose. Thus, the main aim of this study is to investigate recent trends in producing intelligent food packaging using electrospinning technique. In this regard, this paper was categorized into two chief sections, including (a) the principal of electrospinning technique to fabricate fine nanofibers and the parameters affecting the quality of electrospun fibers, and (b) the role of nanofibers as a platform to cover pH indicators in intelligent food packaging.