1,721,015 research outputs found
Co-Polymeric Nanosponges from Cellulose Biomass as Heterogeneous Catalysts for amine-catalyzed Organic Reactions
Full text linkHeterogeneous catalysts prepared from biomass waste sources are attracting increasing interest. The reasons rely on the possibility of combining the virtuous approach of circular economy with the consolidated advantages of heterogeneous catalysis, namely the recycling of the system and the possibility to drive selectivity towards desired products. Herein we report a highly porous cellulose-based nanosponge (CNS) and its use as a recoverable catalyst for Henry and Knoevenagel reactions, two classical amino-catalyzed transformations. The material is obtained by cross-linking between TEMPO-oxidized cellulose nanofibers (TOCNF) and branched polyethyleneimine 25 kDa (bPEI) in the presence of citric acid. CNS have been developed as sorbent materials for water remediation but their use as heterogeneous catalysts was never investigated. The fully characterized micro- and nano-porous system guarantees a complete penetration of CNS, allowing reagents to diffuse within. Indeed, by modulating reaction conditions (catalyst loading, temperature, solvent, microwave versus conventional heating, relative ratio of reagents) it was possible to drive selectivity towards the desired products, while maintaining high efficiency in terms of conversion. The catalyst could be re-used several times without losing in catalytic efficiency. In most cases the products’ distribution is quite different from homogeneous conditions, this much more emphasizing the importance of this heterogeneous solution
Correction to: Influence of cellulose nanofibrils on the rheology, microstructure and strength of alkali activated ground granulated blast-furnace slag: a comparison with ordinary Portland cement (Materials and Structures, (2021), 54, 1, (23), 10.1617/s11527-020-01614-5)
No full textLaura Riva and Carlo Punta have been added to the author group. The change of authorship is due to an error in the recognition of the role and importance of the work of synthesis and characterization of the materials object of the present study, which was not entirely recognized by the inclusion in the acknowledgements. A full recognition of the work performed is obtained by inclusion of the originally omitted authors in the authors’ list. Moreover, a recognition of these authors’ funding body was missing and has been included in the acknowledgement
Life cycle assessment of emerging environmental technologies in the early stage of development: A case study on nanostructured materials
Full text linkThe use of nanostructured materials has been recently proposed in the field of environmental nanoremediation. This approach consists in using nanomaterials not directly, but as building blocks for the design of nano-porous micro-dimensional systems, overcoming the eco- and health-toxicology risks generally associated with the use of nano-sized technologies. Herein we report the use of life cycle assessment (LCA) as an eco-design tool for optimizing the production of cellulose nanosponges (CNS), nanostructured materials recently developed for water remediation purposes. LCA was applied from the acquisition of raw materials to the synthesis of CNS (from cradle-to-gate), considering three production systems, from the lab-level to a modeled scale-up system. The lab-scale LCA identified the main environmental hotspots, namely the energy-consuming steps and the final purification of the material (washing step). In a second lab-scale production, an improvement action could be implemented, switching the washing solvent from methanol to water and decreasing the washing temperature. A second LCA showed a reduced contribution to the impacts from the materials, while the global impacts remained within the same order of magnitude. A simulated scale-up of the process allowed to optimize the energy-consuming steps and the water consumption, through internal recycling. A third LCA assessed the resulting benefits and a decrease in the global impacts by two orders of magnitude. Our study contributes to the discussion of LCA community, providing a focus on the importance of scaling-up of emerging technologies, namely nanostructured porous materials, highlighting the benefits of a LCA based approach since the very beginning of product design (eco-design)
Natural Organic Matter Removal for Disinfection By-Products Control in Climate Change Resilient Drinking Water Treatment
Full text linkDespite extensive experience in disinfected drinking water supply systems, challenges related to disinfection by-products (DBPs) formation still remain, especially considering higher water temperatures and content of natural organic matter (NOM). As part of the EU project safeCREW (http://www.safecrew.org), this research focuses on NOM removal by adsorption, by both batch isotherms and rapid small-scale column tests (RSSCT), comparing 3 commercial activated carbons (AC) and 3 cellulose-based nanostructured sponges (CNS), and testing synthetic and real water samples. NOM was characterized by absorbance and fluorescence and treated samples were subjected to DBPs formation potential tests using sodium hypochlorite and chlorine dioxide. CNS were particularly effective in removing NOM, leading to a relevant decrease in DBPs formation potential. The results are validating through a full-scale monitoring campaign in 2 drinking water treatment plants, collecting samples at the inlet and outlet of the granular AC filters and downstream the disinfection process
Cellulose for the Production of Air-Filtering Systems: A Critical Review
Full text linkThe control of airborne contaminants is of great interest in improving air quality, which has deteriorated more and more in recent years due to strong industrial growth. In the last decades, cellulose has been largely proposed as suitable feedstock to build up eco-friendly materials for a wide range of applications. Herein, the issue regarding the use of cellulose to develop air-filtering systems is addressed. The review covers different cellulose-based solutions, ranging from aerogels and foams to membranes and films, and to composites, considering either particulate filtration (PM10, PM2.5, and PM0.3 ) or gas and water permeation. The proposed solutions were evaluated on the bases of their quality factor (QF), whose high value (at least of 0.01 Pa−1 referred to commercial HEPA (high-efficiency particulate air) filters) guarantees the best compromise between high filtration efficiency (>99%) and low pressure drop (<1 kPa/g). To face this aspect, we first analyzed the different morphological aspects which can improve the final filtration performance, outlining the importance on using nanofibers not only to increase surface area and to modulate porosity in final solutions, but also as reinforcement of filters made of different materials. Besides the description of technological approaches to improve the mechanical filtration, selected examples show the importance of the chemical interaction, promoted by the introduction of active functional groups on cellulose (nano)fibers backbone, to improve filtration efficiency without reducing filter porosity
Nanostructured cellulose-based sorbent materials for water decontamination from organic dyes
Full text linkNanostructured materials have been recently proposed in the field of environmental remediation. The use of nanomaterials as building blocks for the design of nano-porous micro-dimensional systems is particularly promising since it can overcome the (eco-)toxicological risks associated with the use of nano-sized technologies. Following this approach, we report here the application of a nanostructured cellulose-based material as sorbent for effective removal of organic dyes from water. It consists of a micro-and nano-porous sponge-like system derived by thermal cross-linking among (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofibers (TOCNF), branched polyethylenimine 25 kDa (bPEI), and citric acid (CA). The sorbent efficiency was tested for four different organic dyes commonly used for fabric printing (Naphthol Blue Black, Orange II Sodium Salt, Brilliant Blue R, Cibacron Brilliant Yellow), by conducting both thermodynamic and kinetic studies. The material performance was compared with that of an activated carbon, commonly used for this application, in order to highlight the potentialities and limits of this biomass-based new material. The possibility of regeneration and reuse of the sorbent was also investigated
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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