Photocatalytic treatment of municipal wastewater using modified neodymium doped TiO(2) hybrid nanoparticles

Degradation of doxycycline antibiotics using lanthanum copper oxide microspheres under simulated sunlight

In this study, lanthanum copper oxide was synthesized under hydrothermal techniques and characterized for doxycycline degradation. The catalyst exhibited enhanced photocatalytic doxycycline degradation under visible light owing to its compatible bandgap energy (1.7 eV). The XRD data revealed high crystallinity of the material with no noticeable impurities. Three-dimensional microspheres of varying sizes (average diameter of 2.52 μm) were observed from SEM. EDX confirms the successful synthesis of La₂CuO₄. The effect of DC concentration, catalyst dosage, and initial pH on the degradation rate of DC was studied methodically. Interestingly, about 85% of doxycycline (10 mg/L) was degraded within 120 min of light-emitting diode irradiation at pH 10. Oxygen vacancies and surface defects were determined through photoluminescence spectra. The recyclability experiments suggested that the catalyst is capable of degrading DC for three consecutive runs. Radical trapping trials suggested that holes (h⁺), superoxide radicals (^●O₂^-), and hydroxyl radicals (^●OH) are involved in the photodegradation of DC. Herein, the novel approach of La₂CuO₄ synthesis and the efficient visible-light harvesting capability of as-prepared catalyst reveal the potentiality for DC degradation thereby opening a new horizon of research employing La₂CuO₄ used for various environmental applications.

Functional data analysis techniques for the study of structural parameters in polymer composites

This article presents a novel method, based on functional data analysis, to analyse measurements of structural parameters of polymers and polymer composites. The method is demonstrated using newly developed biodegradable conducting polymer composites prepared via a solution casting technique. The measurements of the macro- and microstructural parameters that are used in the characterization of these films are obtained using X-ray diffraction, an impedance analyser and a UV–vis spectrometer. A functional representation of the measured values of the parameters at different dopant concentrations is adopted by viewing them as realizations of a continuous-time stochastic process observed with measurement error. This allows one to estimate the mean functional relationship between a parameter and the dopant concentration. A functional version of principal component analysis is performed, by which the major modes of variation are discovered and the correlations of parameter values at different concentrations are estimated. This provides insight into local and global features of the relationship between these parameters. Some comments are made on how the parameters vary as a function of dopant concentration.

Bi-phasic titanium dioxide nanoparticles doped with nitrogen and neodymium for enhanced photocatalysis

Bi-phasic or multi-phasic composite nanoparticles for use in photocatalysis have been produced by a new synthetic approach. Sol-gel methods are used to deposit multiple layers of active material onto soluble substrates. In this work, a layer of rutile (TiO2) was deposited onto sodium chloride pellets followed by an annealing step and a layer of anatase. After dissolving the substrate, bi-phasic nanoparticles containing half anatase and half rutile TiO2; with "Janus-like" characteristics are obtained. Nitrogen and neodymium doping of the materials were observed to enhance the photocatalytic properties both under UV and white light irradiation. The unique advantage of this synthetic method is the ability to systematically dope separate sides of the nanoparticles. Nitrogen doping was found to be most effective on the anatase side of the nanoparticle while neodymium was found to be most effective on the rutile side. Rhodamine B dye was effectively photodegraded by co-doped particles under white light.

Characterization and photocatalytic performance evaluation of various metal ion-doped microstructured TiO2 under UV and visible light

Commercially available microcrystalline TiO2 was doped with silver, ferrous and ferric ion (1.0 mol %) using silver nitrate, ferrous sulfate and ferric nitrate solutions following the liquid impregnation technology. The catalysts prepared were characterised by FESEM, XRD, FTIR, DRS, particle size and micropore analysis. The photocatalytic activity of the prepared catalysts was tested on the degradation of two model dyes, methylene blue (3,7-bis (Dimethylamino)-phenothiazin-5-ium chloride, a cationic thiazine dye) and methyl blue (disodium;4-[4-[[4-(4-sulfonatoanilino)phenyl]-[4-(4-sulfonatophenyl)azaniumylidenecyclohexa-2,5-dien-1-ylidene]methyl]anilino]benzene sulfonate, an anionic triphenyl methane dye) under irradiation by UV and visible light in a batch reactor. The efficiency of the photocatalysts under UV and visible light was compared to ascertain the light range for effective utilization. The catalysts were found to have the anatase crystalline structure and their particle size is in a range of 140-250 nm. In the case of Fe(2+) doped TiO2 and Fe(3+) doped TiO2, there was a greater shift in the optical absorption towards the visible range. Under UV light, Ag(+) doped TiO2 was the most efficient catalyst and the corresponding decolorization was more than 99% for both the dyes. Under visible light, Fe(3+) doped TiO2 was the most efficient photocatalyst with more than 96% and 90% decolorization for methylene blue and methyl blue, respectively. The kinetics of the reaction under both UV and visible light was investigated using the Langmuir-Hinshelwood pseudo-first-order kinetic model. Kinetic measurements confirmed that, Ag(+) doped TiO2 was most efficient in the UV range, while Fe(3+) doped TiO2 was most efficient in the visible range.

Fabricated nanoparticles: current status and potential phytotoxic threats

Nanotechnology offers unique attributes to various industrial and consumer sectors, and has become a topic of high interest to scientific communities across the world. Our society has greatly benefitted from nanotechnology already, in that many products with novel properties and wide applicability have been developed and commercialized. However, the increased production and use of nanomaterials have raised concerns about the environmental fate and toxicological implications of nanoparticles and nanomaterials. Research has revealed that various nanomaterials may be hazardous to living organisms. Among biota, plants are widely exposed to released nanomaterials and are sensitive to their effects. The accumulation of nannmaterials in the environment is a potential threat, not only because of potential damage to plants hut also because nanoparticles may enter the food chain. Although the literature that addresses the safety of nanoproducts is growing, little is known about the mechanisms by which these materials produce toxicity on natural species, including humans. In this paper, we have reviewed the literature relevant to what phytotoxic impact fabricated nanoparticles (e.g., carbon nanotubes, metallic and metal oxide nanoparticles, and certain other nanomaterials) have on plants. Nanoparticles produce several effects on plant physiology and morphology. Nanoparticles are known to affect root structure, seed germination, and cellular metabolism. Nanoparticles inhibit growth, induce oxidative stress, morphogenetic abnormalities and produce clastogenic disturbances in several plant species. The size, shape and surface coating of NPs play an important role in determining their level of toxicity. Of course, the dose, route of administration, type of dispersion media, and environmental exposure also contribute to how toxic nanoparticles are to plants. Currently, nanotoxicity studies are only in their initial phases of development and more research will be required to identify the actual threat nanoproducts pose to the plant system. To date, data show that there is a large variation in the phytotoxicity caused by different NPs. Moreover, the studies conducted thus far have mostly relied on microscopy to detect effects. Studies that incorporate measures and analyses undertaken with more modern tools are needed. Among new data that are most urgently needed on NPs is how fabricated NPs behave once released into the environment, and how exposure to them may affect plant resistance, metabolic pathways, and plant genetic responses. In this review, we have attempted to collect, present and summarize recent findings from the literature on nanoparticle toxicity in plants. To strengthen the analysis, we propose a scheme for accessing NP toxicity. We also recommend how the potential challenges presented by increased production and release of NPs should be addressed. It is our belief and recommendation that every nanomaterial-based product be subjected to appropriate toxicity and associated assessment before being commercialized.