Thermodynamic Behavior of Polyalcohols and Speciation Studies in the Presence of Divalent Metal Cations

The acid–base properties and complexing ability of some biologically relevant polyalcohols (erythritol, sorbitol, maltol, and ethylmaltol) toward bivalent metal cations have been determined by pote..

Thermodynamic Solution Properties of a Biodegradable Chelant (L-glutamic-N,N-diacetic Acid, L-GLDA) and Its Sequestering Ability toward Cd2+

The thermodynamics of the interaction of L-glutamic-N,N-diacetic acid (GLDA) with protons was studied potentiometrically at different temperatures, ionic strengths and ionic media. Four protonation constants and corresponding enthalpy changes occurred at infinite dilution together with temperature and ionic strength coefficients. The medium effect was also interpreted in terms of the formation of weak complexes between the ligand and the cations of supporting electrolytes, resulting in a greater tendency of GLDA to chemically interact with Na+ rather than K+ and, in turn, (CH3)4N+. Formation constants of GLDA with Cd2+ were determined in NaCl(aq) at different ionic strength values. Five complex species were found, namely CdL2−, CdHL−, CdH2L0(aq), Cd2L0(aq), and Cd(OH)L3−, whose formation constant values at infinite dilution were log β = 12.68, 17.61, 20.76, 17.52, and 1.77, respectively. All the species results were relevant in the pH range of natural waters, although the Cd2L0(aq) was observed only for CCd ≥ CGLDA and concentrations of >0.1 mmol dm−3. The sequestering ability of GLDA toward Cd2+, evaluated by means of pL0.5, was maximum at pH~10, whereas the presence of a chloride containing a supporting electrolyte exerted a negative effect. Among new generation biodegradable ligands, GLDA was the most efficient in Cd2+ sequestration.The authors C.B., P.C., A.I., G.L. and C.D.S. thank the University of Messina for the Research and Mobility 2017 Project (cod. 009041). Authors thank COST action CA18202—Network for Equilibria and Chemical Thermodynamics Advanced Research for the support to this study. O.G.-L. is grateful to the project IT-742-13 for Consolidated Research Groups, funded by the Basque Country Government, for her post-doctoral contract

Sugar-derived bio-based resins as platforms for the development of multifunctional hybrids with potential application for stone conservation

This research is focused on the design of a bio-based epoxy-silica hybrid, enriched with SiO2 nanoparticles, to be used in stone conservation. For this purpose, isosorbide, a sugar derivative coming from renewable sources, was selected for the development of epoxy thermosets that were functionalized adding fixed amounts of silicaforming mixtures, to gain hybrid organic-inorganic networks. Fourier Transform Infrared (FTIR), Attenuated Total Reflection Infrared (ATR-FTIR) and Raman spectroscopies were exploited to follow the synthetic procedures, whereas the homogeneity of the networks was ascertained by scanning electron microscopy/energydispersive X-ray spectroscopy (SEM-EDS). The materials were investigated by thermogravimetric (TG-DTA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and contact angle measurements. Once the proper epoxy-silica product was identified, specifically synthesized nanoparticles were incorporated. The obtained nanocomposite showed excellent thermo-mechanical (Tonset, Tg and Tα of 327, 55.9 and 70.1 ◦C, respectively) and hydrophobic (105◦) properties making it a potential candidate for stone conservation.This work has been financially supported by the project PHETRUM (CTQ2017-82761-P) from the Spanish Ministry of Economy, Industry and Competitiveness (MINECO) and by the European Regional Development Fund (FEDER). The authors gratefully acknowledge Open Access funding provided by University of Basque Country. P. Irizar gratefully acknowledges his predoctoral grant from the MINECO (PRE2018-085888). O. Gomez-Laserna is grateful to the projects IT-742-13 for Consolidated Research Groups, funded by the Basque Country Government, and PHETRUM (CTQ2017-82761-P) from the MINECO for her post-doctoral contract. P. Cardiano thanks the Italian Ministry of University and Research (MIUR), PON R&I project AGM for CuHe (ARS01_00697), for Contact Angle measurements. The authors are grateful to the technical support provided by the Raman-LASPEA laboratory, the Nuclear Magnetic Resonance laboratory and to the Macrobehaviour, Mesostructure, Nanotechnology: Unit of Materials and Surfaces of The Advanced Research Facilities of the SGIker (UPV/EHU, MICINN, GV/EJ, ERDF and ESF)

Non-Invasive Approach to Investigate the Mineralogy and Production Technology of the Mosaic Tesserae from the Roman Domus of Villa San Pancrazio (Taormina, Italy)

The archaeological excavations at Villa San Pancrazio (Taormina, Italy) are bringing to light a vast Roman-Imperial residential quarter featuring luxurious dwellings decorated with wall paintings and mosaic floors, pointing it out as one of the most significant archaeological sites of the city. The polychrome and black and white mosaics recovered date back to the middle Imperial period, during the 2nd century AD. This work deals with the first archaeometric investigations of the materials employed for the tesserae production with the aim of elucidating the mineralogical composition and obtaining analytical evidence that can contribute to extracting information related to their production technology. For that purpose, a non-invasive methodology, based on micro energy dispersive X-ray fluorescence (μ-EDXRF) spectrometry and Raman spectroscopy, was used to characterize a wide selection of stone, ceramic and glass tesserae. Chemometric tools were exploited to manage the large set of elemental data collected on black and white lithic samples, providing essential clues for the subsequent investigations. The results evidenced the employment of natural lithotypes (calcareous sedimentary, dolomitic and volcanic) local and imported, and also artificial materials, such as ceramic made firing magnesium-rich clays, soda-lime-silica glasses made with different opacifying and coloring agents (such as calcium antimoniate, cobalt and copper)This work was supported by project IT-742-13 for Consolidated Research Groups, funded by the Basque Country Government. P. Irizar gratefully acknowledges his predoctoral grant (PRE2018-085888) from the MINECO Spanish Ministry. O. Gómez-Laserna is grateful to the University of the Basque Country (UPV/EHU) for her postdoctoral contract. P. Cardiano also thanks University of Messina (FFABR UNIME 2020) for funding

Binary and ternary complexes of epinephrine with alginate and biologically and environmentally relevant metal cations

The speciation of epinephrine (Eph−) in the presence of alginate (Alg2-) and two biological and environmental relevant metal cations (Cu2+, UO22+) was investigated at T = 298.15K, I = 0.15–1.00 mol dm−3 in NaCl(aq). The formation of binary and ternary complexes was evaluated and, since epinephrine can behave as a zwitterion, the Eph−/Alg2- interaction was studied by means of DOSY NMR. The dependence of the equilibrium constants on ionic strength was studied using an extended Debye-Hückel type equation and the SIT approach. The effect of temperature was investigated by means of isoperibolic titration calorimetry: the entropic contribution was the driving force for the Cu2+/Eph− complexes formation. The sequestering ability of Eph− and Alg2- on Cu2+, evaluated by the pL0.5 calculation, increased with pH and ionic strength. The determination of pM parameter showed that Eph− had a higher Cu2+ affinity with respect to Alg2-. The formation of Eph−/Alg2- species was also investigated by UV-Vis spectrophotometry and 1H NMR measurements. The ternary Cu2+/Eph−/Alg2- and Cu2+/UO22+/Eph− interactions were also studied. The “extra-stability” calculated for the mixed ternary species confirmed that their formation was thermodynamically favorable

Speciation Studies of Bifunctional 3-Hydroxy-4-Pyridinone Ligands in the Presence of Zn2+ at Different Ionic Strengths and Temperatures

The acid-base properties of two bifunctional 3-hydroxy-4-pyridinone ligands and their chelating capacity towards Zn2+, an essential bio-metal cation, were investigated in NaCl aqueous solutions by potentiometric, UV-Vis spectrophotometric, and 1H NMR spectroscopic titrations, carried out at 0.15 ≤ I/mol -1 ≤ 1.00 and 288.15 ≤ T/K ≤ 310.15. A study at I = 0.15 mol L-1 and T = 298.15 K was also performed for other three Zn2+/Lz- systems, with ligands belonging to the same family of compounds. The processing of experimental data allowed the determination of protonation and stability constants, which showed accordance with the data obtained from the different analytical techniques used, and with those reported in the literature for the same class of compounds. ESI-MS spectrometric measurements provided support for the formation of the different Zn2+/ligand species, while computational molecular simulations allowed information to be gained on the metal-ligand coordination. The dependence on ionic strength and the temperature of equilibrium constants were investigated by means of the extended Debye-Hückel model, the classical specific ion interaction theory, and the van't Hoff equations, respectively

Adsorption isotherms and kinetics of rare earth metals on multifunctional materials from various waste pomaces

This contribution presents the preliminary results obtained using waste biomasses from the industrial food chain for the preparation of multifunctional materials possibly able to detect, bind and extract, efficiently and selectively, rare earth metal ions from aqueous solutions simulating real matrices. These metals belong to the list of “Critical Raw Materials”, i.e. the group of materials whose recovery is considered strategic by the European Community. The use of food-processing industry wastes as secondary raw materials offers a sustainable and environmentally friendly approach, that could also be useful for the rare earth metals recovery. In particular, the adsorption of neodymium and dysprosium ions in aqueous solution was studied at pH ~ 5 and t = 25°C using different waste biomasses, namely Bergamot Pomace (BP), Olive Pomace (OP) and Grape Pomace (GP), chemically pretreated at t = 30°C with H2O and HNO3 0.10 mol dm-3 . The materials were characterized employing different analytical techniques; through the FT-IR ATR spectroscopy 2, it was possible to confirm the presence of functional groups capable of interacting with the above mentioned metals. To evaluate their adsorption capacity, batch experiments were carried out on different solutions containing the metal ions (M3+ = Nd3+, Dy3+). The concentration of each M3+ was determined by ICP-OES . The results obtained from adsorption experiments show that Langmuir equation was the best isotherm fitting model for BP, OP and GP for the rare earth metals adsorption. The adsorption equilibrium was reached within 24 hours and the kinetic of adsorption was well described by the pseudo-second order model. Then the recovery of the metals adsorbed on the biomasses was carried out using HNO3, but the reused materials show lower performance than the starting ones, exception done for BP, which showed great reutilization capacitie

Hydroxypyridinone-Based Metal Chelators towards Ecotoxicity: Remediation and Biological Mechanisms

Hydroxypyridinones (HPs) are recognized as excellent chemical tools for engineering a diversity of metal chelating agents, with high affinity for hard metal ions, exhibiting a broad range of activities and applications, namely in medical, biological and environmental contexts. They are easily made and functionalizable towards the tuning of their pharmacokinetic properties or the improving of their metal complex thermodynamic stabilities. In this review, an analysis of the recently published works on hydroxypyridinone-based ligands, that have been mostly addressed for environmental applications, namely for remediation of hard metal ion ecotoxicity in living beings and other biological matrices is carried out. In particular, herein the most recent developments in the design of new chelating systems, from bidentate mono-HP to polydentate multi-HP derivatives, with a structural diversity of soluble or solid-supported backbones are outlined. Along with the ligand design, an analysis of the relationship between their structures and activities is presented and discussed, namely associated with the metal affinity and the thermodynamic stability of the corresponding metal complexes.</jats:p

Hydroxypyridinone-Based Metal Chelators towards Ecotoxicity: Remediation and Biological Mechanisms

Hydroxypyridinones (HPs) are recognized as excellent chemical tools for engineering a diversity of metal chelating agents, with high affinity for hard metal ions, exhibiting a broad range of activities and applications, namely in medical, biological and environmental contexts. They are easily made and functionalizable towards the tuning of their pharmacokinetic properties or the improving of their metal complex thermodynamic stabilities. In this review, an analysis of the recently published works on hydroxypyridinone-based ligands, that have been mostly addressed for environmental applications, namely for remediation of hard metal ion ecotoxicity in living beings and other biological matrices is carried out. In particular, herein the most recent developments in the design of new chelating systems, from bidentate mono-HP to polydentate multi-HP derivatives, with a structural diversity of soluble or solid-supported backbones are outlined. Along with the ligand design, an analysis of the relationship between their structures and activities is presented and discussed, namely associated with the metal affinity and the thermodynamic stability of the corresponding metal complexes