Poultry feathers are among the most abundant and polluting keratin-rich waste biomasses. In this work, we developed a one-pot microwave-assisted process for eco-friendly keratin extraction from ...poultry feathers followed by a direct electrospinning (ES) of the raw extract, without further purification, to obtain keratin-based bioplastics. This microwave-assisted keratin extraction (MAE) was conducted in acetic acid 70% v/v. The effects of extraction time, solvent/feathers ratio, and heating mode (MAE vs. conventional heating) on the extraction yield were investigated. The highest keratin yield (26 ± 1% w/w with respect to initial feathers) was obtained after 5 h of MAE. Waste-derived keratin were blended with gelatin to fabricate keratin-based biodegradable and biocompatible bioplastics via ES, using 3-(Glycidyloxypropyl)trimethoxysilane (GPTMS) as a cross-linking agent. A full characterization of their thermal, mechanical, and barrier properties was performed by differential scanning calorimetry, thermogravimetric analysis, uniaxial tensile tests, and water permeability measurements. Their morphology and protein structure were investigated using scanning electron microscopy and attenuated total reflection-infrared spectroscopy. All these characterizations highlighted that the properties of the keratin-based bioplastics can be modulated by changing keratin and GPTMS concentrations. These bioplastics could be applied in areas such as bio-packaging and filtration/purification membranes.
This paper presents the results obtained from the thermal analysis of a set of geomaterials (clays, pyroclastic materials, and industrial recycled materials) to be used as raw materials for the ...synthesis of geopolymers, specifically designed for the conservation of Cultural Heritage (CH) buildings, particularly in seismic hazard zones such as Sicily. X-ray diffraction and gas volumetric analysis (calcimetry) were applied to this set of raw materials in order to characterize the materials from the chemical and structural point of view. Thermogravimetric analysis (TG), TG coupled to Fourier transform infrared spectroscopy (TG-FTIR), and differential scanning calorimetry were used to characterize their thermal behavior. The statistical treatment of the thermogravimetric data by principal component analysis and hierarchical clustering analysis highlights the direct relation between the thermal data and the material composition that will be exploited for the selection of the best materials to obtain geopolymers specifically designed for the conservation of CH buildings.
The global interest on microwave assisted chemistry (MAC) is due to the important benefits for the sustainable growth of green chemical industries and environmentally friendly progress of society. ...MAC has been firstly developed using oven-type microwaves (MWs) assisted reactors, which requires difficult and expensive industrial scale-up. In 2002, the development of coaxial dipole antenna allowed a direct application of MWs in situ in the reaction media, opening a crucial, novel versatile technological solution, making MW-assisted processes feasible in any configuration at any industrial level. Here, we present an overview of the technological development of 20 years research using a coaxial MW antenna for green chemistry and human health applications. The major MW technology breakthroughs described in these short-review are: i) MW-induced thermoablation machine, ii) in situ MW heating in open glassware chemical reactors, iii) electrodeless MW/ultraviolet (UV) lamps and photoreactors, iv) MW-high pressure reactor and v) solventless/simultaneous MW/UV/ultrasound (US) configurations. Applications for the synthesis of nanocatalysts, nanoparticles and polymers, advanced oxidative decomposition photochemical processes, solvothermal extraction of valuable products and biomass processing are discussed. Remarks on the scaling up of the extraction processes and frontier applications addressed to the treatment of current and future outbreak pandemic emergences are also shown.
Display omitted
•Novel coaxial microwave technology to apply microwave inside the reacting medium.•In-situ activation of the synthesis of nanoparticles.•Coaxial microwave technology for the extraction essential oils and proteins.•Combined microwave/ultrasound/ultraviolet irradiation technologies.•The coaxial microwave technology is scalable at industrial level.
Deep eutectic solvents (DESs) are a class of versatile and green emerging materials. Despite the huge amounts of applications proposed in the last years, studies on their thermal stability are often ...missing. In this short review, we propose a guide for a correct evaluation of DES thermal stability, conducted mainly by dynamical thermogravimetry (TGA). We collected all the data reported in the literature on choline chloride (ChCl)-based DESs, as proof of concept to show the potentialities of the technique, highlighting all the parameters that need to be considered for a correct analysis, with particular attention to the possible sources of misleading interpretations (e.g. the adsorbed water, or the formation of undesired products during DES preparation). In many cases, the additional use of isothermal TGA, or TGA coupled with online techniques such as Fourier Infra-Red Spectroscopy or Mass Spectrometry, may help for the data interpretation. Besides, we summarize in a graph the degradation temperatures of many DESs and their precursors, intended as an operative guide to choosing the correct DES for different applications. The findings reported to date, highlight the potentialities of thermal analysis on DESs, as a powerful tool to obtain essential information on their applicability, and to implement the knowledge of their nanostructure from a molecular point of view.
Display omitted
•General guidelines for a correct evaluation of DES thermal stability.•Collection of degradation temperatures for all the choline chloride-based DESs.•Comparation of short-term and long-term thermal stability for DES.•Potentialities of TGA coupled with MS or FTIR to study DES thermal stability.
Oregano essential oil (OEO) has antioxidant, antiproliferative, anti-inflammatory and antimicrobial activities. OEO could be administered orally for some gastrointestinal diseases, however, its oral ...use, is severely hampered by its irritant taste, which requires a high dilution in water before administration, and by its high susceptibility to light and humidity. Moreover, phenols have a high instability during digestion, and are rapidly metabolized, so that only a small fraction of the oral dose reaches the lower gut. Protection of OEO from degradation in the gastrointestinal tract is essential for its enhanced efficacy and sustained release The aim of this work has been the preparation and characterization of tablets based on hydroxypropyl methylcellulose (HPMC) granules containing OEO adsorbed on zeolite and coated with Eudragit® E PO to protect the oil from instability. Measurements of angle of repose demonstrated that OEO-containing zeolite granules were not cohesive and could be easily compressed. The obtained coated tablets had sufficient mechanical strength and were able to prevent the oxidation of polyphenols in the stomach, indeed only the 15 and 30 % of them was released in simulated jejunal and ileal fluid, respectively. These solid dosage forms protect phenols contained in OEO from degradation and volatilization, as suggested by TG analysis.
•Encapsulation of the oil in a solid form enhances its physical and chemical stability.•Tablets containing oregano essential oil were prepared.•Coated tablets protect phenols during digestion.•Tablets are less expensive than capsules and have a better stability.•The coating protects the oil from instability and volatilization.
Display omitted
•Reuse of Sicilian volcanic residues as precursors for alkali-activated materials.•TGA, TG coupled to FT-IR and X-ray µCT have been used to define the influence of ...reactants.•Multidisciplinary approach for the optimization of the mix design.
Insights on thermal behavior and microstructures of AAMs based on Sicilian volcanic precursors (i.e., volcanic ash, “ghiara” and pumice) have been performed. A multidisciplinary approach by means of thermogravimetric analysis coupled to Fourier Transform Infrared Spectroscopy and X-ray Computed Microtomography has been used with the aim to define the influence of reactants involved in the process. The obtained results show: i) the increase of metakaolin shifts the gas emission toward lower temperatures; ii) the positive relation between mass loss and liquid/solid ratio; iii) the influence of particle size of precursors on the pore development.
•High protein structural order of gelatin and gelatin/keratin electrospun materials.•Correlations between gelatin secondary structure and mechanical performances.•Cellular stress dependent on ...mechanical properties and protein structural order.
The possibility of using protein-based materials as cellular scaffold strongly depends on protein conformation, and several attempts have been made by researchers to obtain scaffold with morphology miming the extracellular matrix. It is widely recognized that the secondary structure of proteins affects the mechanical and biological properties of protein-based scaffolds. However, few studies have been published, and an exhaustive explanation is still missing. In this work the study of the gelatin structure in gelatin-based materials and the investigation of the possible correlations between structure, mechanical and biological features is reported.
We have examined how the secondary structure of gelatin is affected (i) by the process used to obtain the biomaterials (solvent casting vs. electrospinning), (ii) by the concentration of cross linker (3-(Glycidyloxypropyl)trimethoxysilane) (GPTMS), and (iii) by the raw keratin extract added. Gelatin electrospun materials have shown a content of ordered structure higher than gelatin casted films, likely due to the random coil – α-helix transition occuring during electrospinning. GPTMS gives a decrease of ordered structures in gelatin casted films (random structure increasing from 20% to 60%), while it does not affect the percentage of ordered structure in electrospun samples. In the gelatin/keratin electrospun biomaterials, the presence of keratin produces a decrease of α-helix content from 31% to 2–15% and an increase of β-structures, promoting the conversion from antiparallel to parallel β-sheet. The structure of gelatin affects the mechanical performances of biomaterials. In gelatin/keratin electrospun biomaterials we have found a positive correlation between failure strain and helix conformation and a negative correlation with β-structures. Elastic modulus has opposite correlations. All gelatin-based biomaterials have been tested as scaffold for pre-osteoblastic cells showing good biocompatibility for both casted films and electrospun biomaterials.
Display omitted
Novel green extractions aim at the full valorization of aromatic herbs along with the minimization of energy consumption, extraction time and cost of the processes. In this perspective, a ...simultaneous ultrasound and microwave irradiation extraction method (US-IMWAE) for the full valorization of aromatic herbs is here presented. This green approach has been applied to the isolation of essential oils (EOs), hydrosols and solid residues from lavender and rosemary plants. The yields of US-IMWAE in terms of EO weight percentage (wt%), polyphenols concentration and thermochemical characteristics of the solid residues have been compared with microwave assisted extraction (IMWAE) and hydrodistillation (HD). The composition profiles of EOs and hydrosols have been analyzed and quantified by head space gas chromatography mass spectrometry (HS-GC–MS), liquid chromatography with UV/visible diode array/fluorescence detector (HPLC-DAD-FD) and the Folin-Ciocalteu test for the total phenolic content (TPC). Solid residues as valuable by-products have been investigated by FTIR spectroscopy in tandem with chemometrics, thermogravimetric analysis (TGA) and combustion calorimetry. We found that the US-IMWAE green extraction method has produced higher yields of EOs with appealing composition profiles for cosmetic, fragrance and perfume industries (lavender), and for pharmacology and medical applications (rosemary). The high concentration of rosmarinic acid and the total phenolic content in hydrosols obtained with the US-IMWAE method, highlights its great potential. Chemometric analysis of solid residues has found that cellulose is the main component followed by hemicellulose and lignin. The experimental values of enthalpy of combustion of the solid residues (ΔcH) match with the corresponding calculated values and confirm their energetic features and their potential uses as alternative biomass for fuel production. US-IMWAE is environmentally friendly, highly flexible, controllable, and it enables to break the scale-up barrier in ultrasounds and microwave assisted industrial processes. Thus, US-IMWAE has a great potential to reduce EO production costs, and to increase local farm income through the full exploitation of aromatic herbs.
Display omitted
•Simultaneous irradiation of ultrasounds and microwaves in an integrated extractor.•Full valorization of aromatic herbs by exploiting the different fractions.•Combined ultrasonic and microwave irradiation enhances essential oil and hydrosol properties.•Enthalpy of combustion highlighted the energetic features of solid residues.•Green extraction in terms fast processing and for their innovative use of alternative energies.
Abstract Geopolymers have been recently proposed for restoration of built heritage to substitute traditional mortars. Local materials and industrial wastes from the Italian region Sicily showed their ...potential as low-cost aluminosilicate sources for the preparation of geopolymers. Here, a set of Sicilian clays was studied by Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC), and its mineralogical composition was evaluated by X-ray diffraction (XRD). The raw materials were used to prepare geopolymers by alkaline activation with or without the addition of silicate. The thermal degradation profile of the final materials was studied by TGA and compared with that of the precursors, and the energetics of dehydration were investigated by DSC. Two statistical analyses (made by Principal Component Analysis) were performed on the TG data of raw materials and geopolymers and on the TG data of geopolymers and their mineralogical composition, respectively. The last analysis in particular showed a correlation between the mineralogical composition of the materials and the samples' thermal properties. Additional studies of samples subject to accelerated aging by UV irradiation and exposure to acetic acid vapors highlighted the different effects of these two agents on the samples’ stability. Graphical abstract
PDF
