Auswahl der wissenschaftlichen Literatur zum Thema „Nanomaterials recyclability“

The application of carbon-based nanomaterials with high photothermal conversion efficiencies in solar desalination has the advantages of economy, environmental protection, availability and sustainability.

Abstract In recent years, the demand for environment-friendly products has been on an increasing trend among researchers and industry for sustainable development. Deep eutectic solvents are green solvents which, due to their properties (biodegradability, recyclability, low cost, availability, easy preparation, low toxicity, chemical and thermal stability), can be used in various fields such as polymer chemistry, which includes nanocellulose isolation and polysaccharides processing. Several studies have illustrated the effectiveness of using deep eutectic solvents instead of the conventional reaction system to produce and disperse nanomaterials. This work summarizes the use of deep eutectic solvents in the isolation of cellulosic nanomaterials from different types of biomass. Deep eutectic solvents demonstrate high effectiveness in swelling lignocellulosic biomass and producing cellulose nanomaterials. Overall, deep eutectics solvents represent an innovative and effective pretreatment process for the fractionation of raw cellulose-containing fibres to promote subsequent isolation of nanomaterials made from cellulose.

The recyclability of Li-ion batteries is a critical goal but is technically challenging and often impractical due to the complex structure of mixed materials and the irreversible process of production. We investigated the use of organic small molecule self-assembled nanoribbons as an electrolyte material because they offer precise spatial arrangement, high surface areas, tunable surface chemistry, and most notably here, reversible structural formation. In this study, we synthesized nanoribbons by self-assembly of aramid-containing amphiphiles that overcome structural stability problems, and we systematically modified the surface chemistry to promote Li-ion conductivity. We investigated the performance and transport mechanism of these supramolecular nanomaterials as a solid electrolyte for Li-ion batteries. Furthermore, we show direct recyclability of the end-of-life cell. Figure 1

Responsive polymers undergo reversible or irreversible physical or chemical modifications in response to a change in environment or stimulus, e.g., temperature, pH, light, and magnetic or electric fields. Polymeric nanoparticles (NPs), which constitute a diverse set of morphologies, including micelles, vesicles, and core-shell geometries, have been successfully prepared from responsive polymers and have shown great promise in applications ranging from drug delivery to catalysis. In this review, we summarize pH, thermo-, photo-, and enzymatic responsiveness for a selection of polymers. We then discuss the formation of NPs made from responsive polymers. Finally, we highlight how NPs and other nanomaterials are enabling a wide range of smart applications with improved efficiency, as well as improved sustainability and recyclability of polymeric systems.

Since CO2 is an important component of gas emissions, its removal from gas streams is of the utmost importance to fulfill various environmental requirements. The technologies used to accomplish this removal are based mainly on absorption, as well as adsorption and membrane processing. Among the materials used in the above separation processes, materials in nano forms offer a potential alternative to other commonly used macromaterials. The present work reviews the most recent publications (2023) about CO2 capture using different nanomaterials, and whilst most of these publications were dedicated to investigating the above, several presented data on the separation of CO2 from other gases, namely nitrogen and methane. Furthermore, a number of publications investigated the recyclability of nanomaterials under continuous use, and just three of the references were about computational modeling; all others were experimental papers, and only one reference used a real industrial gas.

Here, we report a visible light-induced-trimetallic catalyst (Cu0.5Zn0.5Fe2O4) prepared through green synthesis using Tilia plant extract. These nanomaterials were characterized for structural and morphological studies using powder x-ray diffraction (P-XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The spinel crystalline material was ~34 nm. In benign reaction conditions, the prepared photocatalyst oxidized various benzylic alcohols with excellent yield and selectivity toward aldehyde with 99% and 98%; respectively. Aromatic and aliphatic alcohols (such as furfuryl alcohol and 1-octanol) were photo-catalytically oxidized using Cu0.5Zn0.5Fe2O4, LED light, H2O2 as oxidant, 2 h reaction time and ambient temperature. The advantages of the catalyst were found in terms of reduced catalyst loading, activating catalyst using visible light in mild conditions, high conversion of the starting material and the recyclability up to 5 times without loss of the selectivity. Thus, our study offers a potential pathway for the photocatalytic nanomaterial, which will contribute to the advancement of photocatalysis studies.

The photocatalytic hydrogen evolution reaction (HER) by water splitting has been studied, using catalysts based on crystalline TiO2 nanowires (TiO2NWs), which were synthesized by a hydrothermal procedure. This nanomaterial was subsequently modified by incorporating different loadings (1%, 3% and 5%) of gold nanoparticles (AuNPs) on the surface, previously exfoliated MoS2 nanosheets, and CeO2 nanoparticles (CeO2NPs). These nanomaterials, as well as the different synthesized catalysts, were characterized by electron microscopy (HR-SEM and HR-TEM), XPS, XRD, Raman, Reflectance and BET surface area. HER studies were performed in aqueous solution, under irradiation at different wavelengths (UV-visible), which were selected through the appropriate use of optical filters. The results obtained show that there is a synergistic effect between the different nanomaterials of the catalysts. The specific area of the catalyst, and especially the increased loading of MoS2 and CeO2NPs in the catalyst substantially improved the H2 production, with values of ca. 1114 μm/hg for the catalyst that had the best efficiency. Recyclability studies showed only a decrease in activity of approx. 7% after 15 cycles of use, possibly due to partial leaching of gold nanoparticles during catalyst use cycles. The results obtained in this research are certainly relevant and open many possibilities regarding the potential use and scaling of these heterostructures in the photocatalytic production of H2 from water.

The aerobic oxidative coupling of aniline is an effective process for producing aromatic azo compounds, which are widely used in the organic chemical industry. The development of heterogeneous catalysts for this reaction would be advantageous because of their recyclability and convenience in posttreatment. In this work, one-dimensional Mn(OH)2 nanostructure with various shapes were synthesized through the adjustment of various surfactants. The as-synthesized Mn(OH)2 nanobelts and nanowires showed superior catalytic activity in the activation of oxygen and aniline. Aromatic azo compounds with a variety of substituents were produced through the coupling of the corresponding anilines without additives under ambient conditions.

Surface-enhanced Raman scattering (SERS) provides an unprecedented opportunity for fingerprinting identification and trace-level detection in chemistry, biomedicine, materials, and so on. Although great efforts have been devoted to fabricating sensitive plasmonic nanomaterials, it is still challenging to batch-produce a SERS substrate with high sensitivity, good reproducibility, and perfect recyclability. Here, we describe a facile fabrication of three-dimensional (3D) hierarchical Au/CuS nanocomposites, in which high-density Au nanotips enable highly SERS-active sensing, and the well-defined microflower (MF) geometry produces perfect signal reproducibility (RSD < 5%) for large laser spot excitations (>50 μm2), which is particularly suitable for practical on-site detection with a handheld Raman spectrometer. In addition, a self-cleaning ability of this Au/CuS Schottky junction photocatalyst under sunlight irradiation allows complete removal of the adsorbed analytes, realizing perfect regeneration of the SERS substrates over many cycles. The mass-production, ultra-sensitive, high-reproducibility, and fast-recyclability features of hierarchical Au/CuS MFs greatly facilitate cost-effective and field SERS detection of trace analytes in practice.

There is an urgent need to reduce global greenhouse gas emissions, yet to date the decarbonization of the transportation industry has been slow and of particular difficulty. While fossil fuel replacements such as biodiesel may aid the transition to a less polluting society, production at the industrial scales required is currently heavily dependent on chemical catalysis. Conventional two-step homogenous routes require the challenging separation of catalyst from the obtained product; however, heterogenous solid catalysts bring new considerations such as material stability, surface area, porosity, deactivation effects, and reduced reactivities under mild conditions. Nanomaterials present an attractive solution, offering the high reactivity of homogenous catalysts without complex recyclability issues. Slightly less reactive, acidic sulfated nanomaterials may also demonstrate greater stability to feedstock impurity, extending lifetime and improved versatility to a range of starting feeds. There remains, however, much work to be done in demonstrating the full-scale feasibility of such catalysts. This review explores recent developments over time in acidic sulfated nanocatalysis for biodiesel production, with particular focus on metal oxides, magnetic nanoparticles, silica-supported nanomaterials, and acidic carbon nanocatalysts. Included are various summaries of current progress in the literature, as well as recommendations for future research.

La durabilité des matériaux est leur capacité à résister dans le temps à l'influence de divers facteurs tels que la température, l'humidité, la rupture, tout en conservant leurs caractéristiques.Les matériaux polymères durables sont la solution contre la pollution de l'environnement. Dans ce contexte, le développement de matériaux polymères durables basés sur des composés biodégradables, que l'on trouve en abondance dans la nature, même à partir de déchets industriels, et qui ont également un faible prix de revient, est une alternative possible aux matériaux basés sur des composés fossiles, qui sont toxiques. En même temps, l'utilisation d'un minimum de produits chimiques est un atout pour la production à grande échelle par les industries. En outre, l'obtention de propriétés avantageuses dans ces conditions, adaptées à certains types d'applications, ajoute de la valeur, ce qui recommande leur utilisation par rapport aux matériaux toxiques.Les oligo- et polysaccharides constituent une matière première appropriée qui pourrait être exploitée dans la conception de matériaux polymères durables. Leur utilisation a déjà suscité un réel intérêt de la part des chercheurs, mais leur application au niveau industriel se heurte à un certain nombre de difficultés : des procédés technologiques inadaptés et de la consommation élevée de solvants et de produits chimiques au coût élevé de l'obtention, du recyclage et de la réutilisation des matériaux, conformément à une économie circulaire, essentielle dans l'approche de la protection de l'environnement. Cette économie circulaire consiste à prolonger le cycle de vie des matériaux en réduisant les déchets. Elle privilégie la réparation, la réutilisation et le recyclage des matériaux le plus longtemps possible. Cette thèse de doctorat présente les résultats obtenus par la synthèse, la caractérisation et le test de matériaux durables à base d'oligo- et de polysaccharides.L'objectif global de la thèse de doctorat est de développer des matériaux durables qui intègrent et exploitent des composés non toxiques, renouvelables, respectueux de l'environnement, bon marché et abondants dans la nature tels que les oligo- et polysaccharides dans une économie circulaire.Les principaux axes de recherche développés dans la thèse sont:- Valorisation de la β-cyclodextrine, de la catégorie des oligosaccharides, et du chitosane, de la catégorie des polysaccharides, dans des systèmes de matériaux durables;- Développement de tels matériaux durables, en utilisant également un minimum d'étapes et un nombre réduit de composés et de solvants respectueux de l'environnement;- Utilisation, en particulier, du chitosane sous forme solide (poudre) pour optimiser les propriétés mécaniques et thermiques des systèmes;- Obtention de propriétés matérielles améliorées par l'introduction d'oligo- et de polysaccharides, par rapport aux systèmes de référence, pour les systèmes à base de chitosane: amélioration des caractéristiques mécaniques et thermiques, et pour les systèmes à base de β-cyclodextrine: optimisation de l'adsorption de divers polluants tels que les antibiotiques, les colorants organiques, les métaux lourds;- Augmenter le potentiel d'application des matériaux dans divers domaines tels que le biomédical, l'emballage alimentaire, les revêtements époxy, l'aérospatiale, en raison des avantages que possèdent les oligo- et les polysaccharides ;- Vérifier la recyclabilité des nanomatériaux à base de β-cyclodextrine afin d'améliorer la durabilité des matériaux
The durability of materials is their ability to withstand over time the influence of various factors such as temperature, humidity and breakage while maintaining their characteristics.Durable polymer materials are the solution to environmental pollution. In this context, the development of sustainable polymer materials based on biodegradable compounds, which are abundant in nature, even from industrial waste, and which also have a low cost price, is a possible alternative to materials based on fossil compounds, which are toxic. At the same time, the use of minimal chemicals is an advantage for large-scale production by industries. In addition, obtaining advantageous properties under these conditions, tailored to certain types of applications, brings added value, which recommends their use over toxic materials.Oligo- and polysaccharides represent a suitable raw material that could be exploited in the design of durable polymeric materials. Their use has already aroused real interest among researchers, but their industrial application faces a number of difficulties: from inadequate technological processes and high consumption of solvents and chemicals to the high costs of obtaining, recycling and reusing materials, in line with a circular economy, which is essential in addressing environmental protection. This circular economy is about extending the life cycle of materials by reducing waste. by promoting the repair, reuse and recycling of materials for as long as possible. This PhD thesis presents the results obtained from the synthesis, characterisation and testing of sustainable oligo- and polysaccharide-based materials.The overall objective of the PhD thesis is to develop durable materials that incorporate and exploit non-toxic, renewable, environmentally friendly, cheap and naturally abundant compounds such as oligo- and polysaccharides in a circular economy.The main research directions developed in the thesis are:- Valorisation of β-cyclodextrin, from the oligosaccharide category, and chitosan, from the polysaccharide category, in sustainable material systems;- Development of such sustainable materials using a minimum number of steps and a reduced number of compounds and solvents;- The use, in particular, of chitosan in solid (powder) form to optimise the mechanical and thermal properties of the systems;- Achieving improved mechanical and thermal properties of the materials by introducing oligo- and polysaccharides, compared to reference systems, for chitosan-based systems, and for β-cyclodextrin-based systems: optimised adsorption of various pollutants such as antibiotics, organic dyes, heavy metals;- increased application potential of materials in various fields such as biomedical, food packaging, epoxy coatings, aerospace, due to the advantages of oligo- and polysaccharides;- Testing the recyclability of β-cyclodextrin-based nanomaterials to improve material durability

Fluoride contamination in groundwater affects about 150 million people worldwide. In this study, the authors focused on synthesizing biopolymer metal oxide nanocomposite for fluoride removal. Nanocomposite material was done using SEM. As(V), Al, Ti, Zr, and Fe water samples were analysed by ICP-MS (inductively coupled plasma-mass spectrometry). Fluoride level was determined using the standard method – Ion-Selective Electrode method. Preliminary results indicate arsenic (V) removal was below the 10 ppb and fluoride less than 1.5 ppm as prescribed by WHO. The removal efficiency was after 60-70 minutes with recyclability of 11 cycles. The nanocomposite worked well in all pH ranges 6.5-8.5. A filter cartridge biopolymer metal oxide nanocomposite constituting of template aluminium homogenized in the aggregated network of chitosan was developed as an adsorbent for fluoride from the water with better adsorption limit.