1,721,040 research outputs found
Polymorphism in Na2(Co/Zn)P2O7 and Na2(Co/Fe)P2O7 Pyrophosphates: A Combined Diffraction and 31P NMR Study
No full textPyrophosphates of the general formula A2BP2O7 (A = alkali metal and B = transition metal) find applications in several technological fields, including rechargeable Na-ion batteries. They present a rich polymorphism vs composition, which may strongly influence their functional properties. Therefore, to selectively obtain a specific structure is crucial for applications. Here, we combine structural investigation techniques (solid-state NMR, X-ray and neutron diffraction, and DFT calculations) to investigate the crystal chemistry of the series Na2(M/M’)P2O7 with couples M/M’ = Co/Zn and Co/Fe. For both the series, a phase transition vs composition is observed. A tetragonal to orthorhombic phase transition is found for the Zn/Co series, and an orthorhombic to triclinic phase transition is found for the Co/Fe series. Such changes are interpreted in view of the different electronic structures of the transition metal ion. In addition, with the support of modeling, short- and long-range structural analysis, we show that the coexistence of two polymorphs for a given composition is possible, suggesting that the final structures may be strongly dependent upon the synthesis procedure
Supercritical CO2 technology for the treatment of end-of-life lithium-ion batteries
No full textThe penetration of Li-ion batteries (LIBs) in the automotive market makes a zero-waste vision for battery recycling urgent. This can play a crucial role in developing a circular economy through the recovery of critical raw materials (CRMs) as well as bringing non-metallic components back to use. In recent years, recycling technologies for LIBs entered a new stage focused on the development of advanced pre-treatment processes to separate all the valuable battery components and more sustainable metallurgical approaches. Compared to common recycling processes, supercritical fluid (SCF) technology has great advantages related to its environmental benignity; chiefly, if CO2 is used as the SCF (scCO2), it is an outstanding solvent for green chemistry approaches. This review aims at providing an overview on the current progresses and open challenges of SCF technology for the treatment of end-of-life LIBs. The fundamentals of SCF technology process are discussed, providing the reader a brief overview of principles, operation procedures and instrumentation. Thereafter, the main applications in the field of battery recycling are reviewed. Successful methods for battery electrolyte recovery via scCO2 are discussed together with pioneering studies on the extraction of critical metals from the cathode that demonstrate promising recovery rates (>60%) for Li, Co, Mn, and Ni. Finally, a specific focus is given on the huge innovation potential of scCO2 to separate and reuse the fluorinated binder from the electrode. At present, the binder is burnt in common recycling processes, leading to hazardous fluorinated gas emissions. This review aims to emphasize the opportunities of the SCF technology in battery waste treatment as a promising approach for resource recovery with significant economy and environmental perspectives
Is It Possible to Obtain Solvent-Free, Li+-Conducting Solid Electrolytes Based on Pure PVdF? Comment on “Self-Suppression of Lithium Dendrite in All-Solid-State Lithium Metal Batteries with Poly(vinylidene difluoride)-Based Solid Electrolytes”
No full textIs It Possible to Obtain Solvent-Free, Li+-Conducting Solid Electrolytes Based on Pure PVdF? Comment on “Self-Suppression of Lithium Dendrite in All-Solid-State Lithium Metal Batteries with Poly(vinylidene difluoride)-Based Solid Electrolytes”
Optical absorption induced by UV laser radiation in Ge-doped amorphous silica probed by in situ spectroscopy
No full textWe studied the optical absorption induced by 4.7eV pulsed laser radiation on Ge-doped a-SiO2 synthe-sized by a sol-gel technique. The absorption spectra in the ultraviolet spectral range were measured during and after the end of irradiation with an in situ technique, evidencing the growth of an absorption signal whose profile is characterized by two main peaks near 4.5eV and 5.7eV and whose shape depends on time. Electron spin resonance measurements performed ex situ a few hours after the end of exposure per-mit to complete the information acquired by optical absorption by detection of the paramagnetic Ge(1) (GeO4)– and Ge-E’ (≡Ge•) centers laser-induced in the samples
Novel sol-gel organic-inorganic hybrid materials for drug delivery
No full textPurpose: The aim of the present study was to synthetize and characterize novel sol-gel organic-inorganic hybrid materials to be used for controlled drug delivery application. Materials and Methods: Organic-inorganic hybrid class I materials based on poly(ε-caprolactone) (PCL 6, 12, 24 and 50 wt%) and zirconia-yttria (ZrO2-5%Y2O3) were synthesized by a sol-gel method, from a multicomponent solution containing zirconium propoxide [Zr(OC2H7)4], yttrium chloride (YCl3), PCL, water and chloroform (CHCl3). The structure of the hybrids was obtained by means of hydrogen bonds between the Zr-OH group (H-donor) in the sol-gel intermediate species and the carboxylic group (H-acceptor) in the repeating units of the polymer. Results: The presence of hydrogen bonds between organic-inorganic components of the hybrid materials was suggested by Fourier transform infrared (FTIR) analysis, and strongly supported by solid-state NMR. A single-step, sol-gel process was then used to precipitate microspheres containing ketoprofen or indomethacin for controlled drug delivery applications. Release kinetics in a simulated body fluid (SBF) were subsequently investigated. The amount of drug released was detected by UV-VIS spectroscopy. Pure anti-inflammatory agents exhibited linear release with time, in contrast drugs entrapped in the organic-inorganic hybrids were released with a logarithmic time dependence, starting with an initial burst effect followed by a gradual decrease. Conclusions: The synthesis of amorphous materials containing drugs, obtained by sol-gel methods, helps to devise new strategies for controlled drug delivery system desig
Chemical characterization and magnetic properties of hybrid materials obtained via sol-gel route
No full textSilica-polyethylene glycol hybrids synthesized by sol-gel: Biocompatibility improvement of titanium implants by coating
No full textConsolidated bioprocessing in engineered B. subtilis lab strains: γ-PGA production from biomass
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The soil bacterium B. subtilis, the model organism for Gram positive bacteria, is the best characterized member of the Bacillus genus, which includes several highly exploited industrial species. Besides industrial enzymes, Bacillus spp. can synthesize poly-γ-glutamic acid (γ-PGA), a nontoxic, biodegradable, highly anionic biopolymer made up of multiple d-/l-glutamic acid monomers joined by amide linkages between the α-NH2 and γ-COOH groups. Thanks to several valuable characteristics, γ-PGA is applied in an expanding range of biotechnological fields (Ogunleye et al., 2015), including applications as drug carrier, gene delivery and scaffold material for tissue engineering (Luo et al., 2016). γ-PGA production is also an ideal model system to develop cost-competitive feedstocks for B. subtilis aerobic fermentations.
Despite B. subtilis possessing a wide array of complex-carbohydrates degrading enzymes, direct transformation of biomass into biocommodities has not yet been reported for this microorganism.
The aim of this work was to obtain economic γ-PGA production using a waste biomass as feedstock. Rice straw is one of the most abundant biomass resources, not in competition with food, for which there are no effective valorisation strategies.
In this study, the cellulolytic capabilities of B. subtilis JH642 were maximized through self-cloning procedures, and a cheap and simple pretreatment to facilitate straw saccharification was developed.
The engineered strain grew efficiently on treated straw. Moreover, by transferring the mutations supporting γ-PGA biosynthesis (Scoffone et al., 2013) into the cellulolytic strain, direct production of γ-PGA from biomass was obtained, definitely proving the applicability of Consolidated Bioprocessing concepts to B. subtilis
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