New technologies have been developed to avoid ecological damages by promoting depollution and eco-friendly synthesis routes of chemicals and materials, and setting efficient “cleaner” energy supply ...methods. These research fields, strongly interconnected, can contribute to sustainable technological advancement and represent the frame in which SrFeO3-based materials can act as valuable tools. SrFeO3 is a ABO3 perovskite-type mixed oxide, widely studied in nanotechnology. Its pristine form does not contain expensive elements, such as rare and noble metals, or toxic components. SF peculiar features, such as non-stoichiometric composition (oxygen vacancies), the unusual oxidation state of Fe4+ and the related transformations of structural, electronic and magnetic characteristics, are attracting many research teams. This review summarizes most of these fundamental aspects, adding tips on some of the possible SF modification strategies and characterization techniques in view of environmental-benign applications. Particularly, thanks to SF-based materials’ oxygen exchange properties, ionic and electronic conduction abilities and catalytic activities, SFs are used in: (i) depollution processes as adsorbents, photo- and thermo-catalysts, combustion catalysts, antimicrobial agents, (ii) alternative devices for energy production and storage, and (iii) efficient systems for fuel conversion (i.e., chemical looping). The main correlations among SF composition, physical-chemical properties, performances and stability will be highlighted. This way, this review addresses indications to create SF-based tailored and functional materials specifically for the environment and energy, which are still underestimated and often replaced by other well-known oxides such as Lanthanum-based (in A-site) or Co, Ti-based (in B-site) perovskites.
•Strontium Ferrate SrFeO3-δ possesses peculiar features with respect to other perovskite oxides.•SrFeO3-δ are employed in different technological fields.•SrFeO3-δ are used as decontaminating agents for water and air by several mechanisms.•SrFeO3-δ can be included in devices for clean energy supply and storage.
The use of hydrogen peroxide (produced in situ or ex situ) as the main agent in oxidative processes of environmental pollutant removal is widely studied. The degradation of water pollutants, such as ...dyes, pharmaceuticals, cosmetics, petroleum derivatives, and even pathogens, has been successfully obtained by different techniques. This review gives an overview of the more recent methods developed to apply oxidative processes mediated by H2O2 and other reactive oxygen species (ROS) in environmental catalysis, with particular attention to the strategies (Fenton-like and Bio-Fenton, photo- and electro-catalysis) and the materials employed. A wide discussion about the characteristics of the materials specifically studied for hydrogen peroxide activation, as well as about their chemical composition and morphology, was carried out. Moreover, recent interesting methods for the generation and use of hydrogen peroxide by enzymes were also presented and their efficiency and applicability compared with the Fenton and electro-Fenton methods discussed above. The use of Bio-Fenton and bi-enzymatic methods for the in situ generation of ROS seems to be attractive and scalable, although not yet applied in full-scale plants. A critical discussion about the feasibility, criticalities, and perspectives of all the methods considered completes this review.
In the present work, the acid-catalyzed interesterification of glyceryl trioctanoate (GTO) with ethyl acetate was investigated as a model reaction for the one-step production of biofuel and its ...additives. The activity of heterogeneous acid catalysts, such as silica-based propyl-sulfonic ones, was evaluated. Propyl-sulfonic groups were grafted on both amorphous and mesoporous silica oxide (SBA-15, KIT-6) using different functionalization processes and characterized by N
adsorpion-desorption isotherm (BET), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and potentiometric titration. During the optimization of the reaction conditions with the most active catalyst (Am-Pr-SO
H), it was shown that the addition of ethanol allowed a total conversion of GTO together with 89% and 56% yield of ethyl octanoate and triacetin, respectively. The catalytic performance is strictly correlated to the catalyst features, in terms of both the acid capacity and the porous structure. Moreover, the catalytic performance is also affected by a synergistic mechanism between silanols and Pr-SO
H groups towards the 'silanolysis' of ethyl acetate. The overall results show that the presence of ethanol, the reaction time, and the amount of catalyst shifts the reaction towards the formation of the biofuel mixture composed by ethyl octanoate and triacetin.
The growing utilization of renewable and residual biomasses for environmental preservation and remediation are important goals to be pursued to minimize the environmental impact of human activities. ...In this paper, sodium alginate (derived from brown algae) was crosslinked using chitosan (mainly derived from the exoskeleton of crustaceans) in the presence of biowaste-derived substances isolated from green compost (BBS-GC), to produce hydrogels and dried films. The obtained materials were tested as adsorbents for wastewater remediation. To this purpose, gels were characterized using a multi-analytical approach and used as active substrates for the removal of three differently-charged molecules, chosen as model pollutants: crystal violet, rhodamine B, and orange II. The effectiveness of the gel formulations was demonstrated and attributed to the variety of active functionalities introduced by the different precursors, the structural factors and the peculiar physicochemical properties of the resulting materials.
The frontiers of antibacterial materials in the biomedical field are constantly evolving since infectious diseases are a continuous threat to human health. In this work, waste-wool-derived keratin ...electrospun nanofibers were blended with copper by an optimized impregnation procedure to fabricate antibacterial membranes with intrinsic biological activity, excellent degradability and good cytocompatibility. The keratin/copper complex electrospun nanofibers were multi-analytically characterized and the main differences in their physical-chemical features were related to the crosslinking effect caused by Cu
. Indeed, copper ions modified the thermal profiles, improving the thermal stability (evaluated by differential scanning calorimetry and thermogravimetry), and changed the infrared vibrational features (determined by infrared spectroscopy) and the chemical composition (studied by an X-ray energy-dispersive spectroscopy probe and optical emission spectrometry). The copper impregnation process also affected the morphology, leading to partial nanofiber swelling, as evidenced by scanning electron microscopy analyses. Then, the membranes were successfully tested as antibacterial materials against gram-negative bacteria,
. Regarding cytocompatibility, in vitro assays performed with L929 cells showed good levels of cell adhesion and proliferation (XTT assay), and no significant cytotoxic effect, in comparison to bare keratin nanofibers. Given these results, the material described in this work can be suitable for use as antibiotic-free fibers for skin wound dressing or membranes for guided tissue regeneration.
Today, the theme of environmental preservation plays an important role within the activities of the scientific community and influences the choices of politics and the common population. In this ...context, the use of non-fossil substances should be promoted for different reasons: to avoid the depletion and damage of the areas involved in the fossil fuel extraction, decrease the impact of emissions/by-products related to the industrial transformation of fossil-based products and possibly exploit residual biomasses as sources of carbon. This latter aspect also can be viewed as a way to revalorize lignocellulose waste, generally destined to dump as putrescible matter or to be incinerated. In this review, we are aiming to present a concise overview of the multiple functions of lignocellulose biomass in the broad field of catalysis for a sustainable development. The originality of the approach is considering the lignocellulose-derived matter in three different aspects: (i) as a precursor to convert into platform molecules, (ii) as an active material (i.e., humic-like substances as photosensitizers) and (iii) as a green support for catalytic applications. We find that this perspective can widen the awareness level of scientists involved in the catalysis field for the exploitation of residual biomass as a valuable and complementary resource.
This study investigated the biodegradation behavior of cotton fabrics treated with polypyrrole, a polymer with conductive and antibacterial properties. Fabric samples were buried in compost-enriched ...soil for 10, 30 and 90 days. The biodegradation level was initially estimated by a visual inspection of the fibers and by the determination of the fabric weight loss. Other physical–chemical changes of fibers during the biodegradation process were analyzed by microscopy, thermal analyses and infrared spectroscopy. The surface resistivity of the fabrics was also measured. The results obtained comparing the bare cotton samples and the polypyrrole-added ones suggested that, on the one hand, polypyrrole hindered/delayed the biodegradation of cotton in compost-enriched soil, probably exercising its inherent antimicrobial feature during the first period of burial. On the other hand, over time, polypyrrole seemed to represent the first compound attacked by the microorganisms, preserving the cotton substrate. Despite the absence of dedicated literature regarding polypyrrole biodegradation, the mechanism hypothesized in this paper involves the loss of conjugation, as a consequence of de-doping, oxidized functionalities up to local cycle breaking.
This study proposes a simple approach for the recognition of polyamide 6.9 samples differing in impurity amounts and viscosities (modulated during the synthesis), which are parameters plausibly ...variable in polymers' manufacturing processes. Infrared spectroscopy (ATR-FTIR) was combined with chemometrics, applying statistical methods to experimental data. Both non-supervised and supervised methods have been used (PCA and PLS-DA), and a predictive model that could assess the polyamide type of unknown samples was created. Chemometric tools led to a satisfying degree of discrimination among samples, and the predictive model resulted in a great classification of unknown samples with an accuracy of 88.89%. Traditional physical-chemical characterizations (such as thermal and mechanical tests) showed their limits in the univocal identification of sample types, and additionally, they resulted in time-consuming procedures and specimen destruction. The spectral modifications have been investigated to understand the main signals that are more likely to affect the discrimination process. The proposed hybrid methodology represents a potential support for quality control activities within the production sector, especially when the spectra of compounds with the same nominal composition show almost identical signals.
The Lab4treat experience has been developed to demonstrate the use of magnetic materials in environmental applications. It was projected in the frame of the European project Mat4Treat, and it was ...tested several times in front of different audiences ranging from school students to the general public in training and/or divulgation events. The experience lends itself to discuss several aspects of actuality, physics and chemistry, which can be explained by modulating the discussion depth level, in order to meet the interests of younger or more experienced people and expand their knowledge. The topic is relevant, dealing with the recycling of urban waste and water depollution. The paper is placed within the field of water treatment for contaminant removal; therefore, a rich collection of recent (and less recent) papers dealing with magnetic materials and environmental issues is described in the Introduction section. In addition, the paper contains a detailed description of the experiment and a list of the possible topics which can be developed during the activity. The experimental approach makes the comprehension of scientific phenomena effective, and, from this perspective, the paper can be considered to be an example of interactive teaching.
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