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Anodic TiO2 nanotube arrays decorated with Ni, Cu, and NiCu alloy thin films were investigated for the first time for the photocatalytic degradation of paracetamol in water solution under UV irradiation. Metallic co-catalysts were deposited on TiO2 nanotubes using magnetron sputtering. The influence of the metal layer composition and thickness on the photocatalytic activity was systematically studied. Photocatalytic experiments showed that only Cu-rich co-catalysts provide enhanced paracetamol degradation rates, whereas Ni-modified photocatalysts exhibit no improvement compared with unmodified TiO2. The best-performing material was obtained by sputtering a 20 nm thick film of 1:1 atomic ratio NiCu alloy: this material exhibits a reaction rate more than doubled compared with pristine TiO2, enabling the complete degradation of 10 mg L−1 of paracetamol in 8 h. The superior performance of NiCu-modified systems over pure Cu-based ones is ascribed to a Ni and Cu synergistic effect. Kinetic tests using selective holes and radical scavengers unveiled, unlike prior findings in the literature, that paracetamol undergoes direct oxidation at the photocatalyst surface via valence band holes. Finally, Chemical Oxygen Demand (COD) tests and High-Resolution Mass Spectrometry (HR-MS) analysis were conducted to assess the degree of mineralization and identify intermediates. In contrast with the existing literature, we demonstrated that the mechanistic pathway involves direct oxidation by valence band holes. [ABSTRACT FROM AUTHOR]

The Japanese textile tradition is renowned for its intricate designs achieved through a variety of dyeing techniques, including kasuri, shibori, and paste-resist dyeing. These techniques are often combined within a single textile, resulting in exceptionally elaborate creations. Our paper delves into the technical aspects and complexities of these methods, highlighting the dynamic interplay between tradition and innovation in Japanese textile production. Our scientific endeavour focused on some textiles dating between the 19th and 20th centuries and belonging to the Montgomery Collection of Japanese folk art. Employing non-invasive techniques such as visible reflectance spectroscopy and ER-FTIR spectroscopy, we uncovered key insights into the materials and methods utilized in the creation of these textiles. Our analysis revealed a diverse array of pigments and dyes, including plant-derived, inorganic, and synthetic variants. These findings illuminate the cultural syncretism between traditional Japanese practices and the adoption of new materials from the West, underscoring the dynamic nature of textile production in Japan. Furthermore, ER-FTIR spectroscopy elucidated the predominant use of cotton as the primary fibre in the textiles, aligning with historical records of Japan's role as a major producer of cotton yarn. Analysis of white areas within the textiles revealed evidence of resist-paste dyeing techniques, particularly tsutsugaki and katazome, through the absence of dye penetration and the characteristic appearance of white lines. Confirmation of indigo dyeing techniques (aizome) was achieved through ER-FTIR spectroscopy, providing reliable identification of indigo and Prussian blue in various shades of blue present in the textiles. Additionally, the detection of Western-derived dyeing method (utsushi-yūzen) and free-hand painting (kaki-e), offers insights into the diversity of dyeing practices employed by Japanese artisans. The presence of proteinaceous materials and synthetic dyes observed in some textiles has implications for conservation practices, suggesting the need for tailored approaches to ensure the preservation of these culturally significant artifacts. Overall, these scientific results shed new light on the materials, techniques, and cultural contexts underlying Japanese textile production, advancing our understanding of this rich artistic heritage and informing future research endeavours in textile science and conservation. [ABSTRACT FROM AUTHOR]

Antimony (Sb) contamination poses significant environmental and health concerns due to its toxic nature and widespread presence, largely from anthropogenic activities. This study addresses the urgent need for an accurate speciation analysis of Sb, particularly in water sources, emphasizing its migration from polyethylene terephthalate (PET) plastic materials. Current methodologies primarily focus on total Sb content, leaving a critical knowledge gap for its speciation. Here, we present a novel analytical approach utilizing frontal chromatography coupled with inductively coupled plasma mass spectrometry (FC-ICP-MS) for the rapid speciation analysis of Sb(III) and Sb(V) in water. Systematic optimization of the FC-ICP-MS method was achieved through multivariate data analysis, resulting in a remarkably short analysis time of 150 s with a limit of detection below 1 ng kg−1. The optimized method was then applied to characterize PET leaching, revealing a marked effect of the plastic aging and manufacturing process not only on the total amount of Sb released but also on the nature of leached Sb species. This evidence demonstrates the effectiveness of the FC-ICP-MS approach in addressing such an environmental concern, benchmarking a new standard for Sb speciation analysis in consideration of its simplicity, cost effectiveness, greenness, and broad applicability in environmental and health monitoring. [ABSTRACT FROM AUTHOR]

The topic of hexavalent chromium (Cr(VI)) in leather has been debated throughout the whole supply chain for years. However, its significance has recently increased due to proposed changes in European legislation concerned with skin-sensitising substances suggesting that acceptable Cr(VI) concentrations in leather goods should be lowered from 3 mg kg−1 to 1 mg kg−1. The proposition of a stricter limit and current analytical difficulties created the need for a review of current standard test methods. The research presented in this paper investigates both the colorimetric (Part 1) and chromatographic (Part 2) methods under BS EN ISO 17075. The focus of the study was to identify possible sources of interference leading to large statistical variance in results and to define the limit of quantification with respect to the proposed new compliance limit. This study into the colorimetric method has shown that the presence of Cr(III), dyes, and proteins can be significant interferences, becoming critical at low Cr(VI) concentrations. Dilution factors worsen the problem of detecting low concentrations: a reliable quantitative detection of 0.01 mg kg−1 and 0.003 mg kg−1 Cr(VI) in solution are required at the 3 mg kg−1 and 1 mg kg−1 compliance limits in leather, respectively. BS EN ISO 17075 part 1 was shown to be incapable of reliably resolving to 3 mg kg−1 or below in leather. Part 2 shows a marked improvement in detection limits and reliability; however, data suggest that 1 mg kg−1 Cr(VI) is not reliably detectable in leather. Suggested improvements to the established test methods and a possible alternative are discussed. [ABSTRACT FROM AUTHOR]

Dinitrogen adsorption on overexchanged Cu-ZSM-5 is examined at 302 K by diffuse reflectance infrared spectroscopy, N2-adsorption isotherms and tempertaure-programmed N2 desorption. The introduction of controlled amounts of impurities, together with the utilization of N(super 15)(sub 2) and CO(super 13) indicate that this band is instead related to hydrated Cu(*I)-CO species formed by accumulation on the sample of traces of H2O in the N2 flow.

Biochar nanoparticles (BC NPs), produced by low temperature pyrolysis (350 °C) of microalgae (Nannochloropsis sp.) and nutshells, are proposed as low-cost and sustainable co-catalysts to promote the photocatalytic activity of TiO2 nanotube (NT) arrays towards the degradation of methylene blue (MB) used as an organic pollutant model molecule. BC NPs (size < 25 nm) were obtained by treating bulk BC (i.e., biomass after pyrolysis) by sonication–centrifugation cycles in a water solution. The filtered BC NPs dispersion was deposited by simple drop-casting on the TiO2 NT support. The BC loading was varied by performing multiple depositions. Photocatalytic experiments under UV light (365 nm) revealed that the decoration with BC NPs significantly improves the TiO2 photoactivity. Such enhancement is mainly influenced by the amount of BC deposited; upon optimizing the BC deposition conditions, the rate of photocatalytic degradation of MB increases approximately three times with respect to bare TiO2, almost irrespective of the nature of the raw material. The greater photocatalytic activity of BC-TiO2 can be attributed to the synergistic combination of reactant/product adsorption and catalytic degradation of the adsorbed organic pollutant, as well as an improved charge carrier separation and electron transfer. [ABSTRACT FROM AUTHOR]