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In this work, the mechanical properties of hydrogels based on linear polyethyleneimine (PEI) chemically crosslinked with ethyleneglycoldiglycidyl ether (EGDE) were improved by the ionic crosslinking with sodium tripolyphosphate (TPP). To this end, the quaternization of the nitrogen atoms present in the PEI structure was conducted to render a network with a permanent positive charge to interact with the negative charges of TPP. The co-crosslinking process was studied by 1H high-resolution magic angle spinning (1H HRMAS) NMR and X-ray photoelectron spectroscopy (XPS) in combination with organic elemental analysis and inductively coupled plasma mass spectrometry (ICP-MS). In addition, the mobility and confinement of water molecules within the co-crosslinked hydrogels were studied by low-field 1H NMR. The addition of small amounts of TPP, 0.03 to 0.26 mmoles of TPP per gram of material, to the PEI-EGDE hydrogel resulted in an increase in the deformation resistance from 320 to 1080%, respectively. Moreover, the adsorption capacity of the hydrogels towards various emerging contaminants remained high after the TPP crosslinking, with maximum loading capacities (qmax) of 77, 512, and 55 mg g−1 at pH = 4 for penicillin V (antibiotic), methyl orange (azo-dye) and copper(II) ions (metal ion), respectively. A significant decrease in the adsorption capacity was observed at pH = 7 or 10, with qmax of 356 or 64 and 23 or 0.8 mg g−1 for methyl orange and penicillin V, respectively.

Abstract The transport sector is in all probability the one that emits the greatest amounts of CO2 and other harmful gases into the atmosphere. Therefore, the emission of greenhouse gases from the combustion of fossil fuels must be significantly reduced to mitigate their harmful effects on the environment. In this sense, bio‐fuels obtained from lignocellulosic biomass are a solution to partially replace fuels from petroleum. However, the biggest challenge facing the scientific community is to decrease the amount of oxygen in bio‐fuels through catalytic hydrodeoxygenation (HDO) reactions. This review offers a broad perspective on the catalytic systems used so far in the HDO processes of model compounds present in bio‐fuels, analyzing in detail the advantages and disadvantages of each system to give a vision towards the future.

Lanthanide molybdates are materials known for their mixed proton–ionic conductivity. This study investigates the effects of Pr content and Nb-doping on the crystal structure and electrical properties of the La5.4−xPrxMo1−yNbyO12−δ (x = 0, 1.35, 2.7, 4.05, 5.4; y = 0, 0.1) series. The research focuses on two primary objectives: (i) enhancing the electronic conductivity through the use of Pr4+/Pr3+ redox pairs and (ii) increasing the ionic conductivity through Nb5+ aliovalent doping. The materials were thoroughly characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission and scanning electron microscopy (TEM and SEM), and complex impedance spectroscopy. The average crystal structure of the materials depended significantly on the Pr content. In general, compositions with a higher Pr content crystallize in a cubic fluorite-type structure, whereas those with a lower Pr content stabilize a rhombohedral polymorph. However, detailed TEM studies reveal a more complex local crystal structure characterized by nanodomains and incommensurate modulations. The highest conductivity values were observed in a N2 atmosphere for compositions with an elevated Pr content, with values of 0.17 and 204.4 mS cm−1 for x = 0 and x = 5.4, respectively, at 700 °C, which is attributed to electronic conduction mediated by the Pr4+/Pr3+ redox pair, as confirmed by XPS. These findings highlight the potential of tailored doping strategies to optimize the conducting properties of lanthanide molybdates for specific high-temperature electrochemical applications. [ABSTRACT FROM AUTHOR]

In this work, the mechanical properties of hydrogels based on linear polyethyleneimine (PEI) chemically crosslinked with ethyleneglycoldiglycidyl ether (EGDE) were improved by the ionic crosslinking with sodium tripolyphosphate (TPP). To this end, the quaternization of the nitrogen atoms present in the PEI structure was conducted to render a network with a permanent positive charge to interact with the negative charges of TPP. The co-crosslinking process was studied by 1H high-resolution magic angle spinning (1H HRMAS) NMR and X-ray photoelectron spectroscopy (XPS) in combination with organic elemental analysis and inductively coupled plasma mass spectrometry (ICP-MS). In addition, the mobility and confinement of water molecules within the co-crosslinked hydrogels were studied by low-field 1H NMR. The addition of small amounts of TPP, 0.03 to 0.26 mmoles of TPP per gram of material, to the PEI-EGDE hydrogel resulted in an increase in the deformation resistance from 320 to 1080%, respectively. Moreover, the adsorption capacity of the hydrogels towards various emerging contaminants remained high after the TPP crosslinking, with maximum loading capacities (qmax) of 77, 512, and 55 mg g−1 at pH = 4 for penicillin V (antibiotic), methyl orange (azo-dye) and copper(II) ions (metal ion), respectively. A significant decrease in the adsorption capacity was observed at pH = 7 or 10, with qmax of 356 or 64 and 23 or 0.8 mg g−1 for methyl orange and penicillin V, respectively. [ABSTRACT FROM AUTHOR]

This research explores the integration of DUT-67 metal organic frameworks into polyethyleneimine-based hydrogels to assemble a composite system with enough mechanical strength, pore structure and chemical affinity to work as a sorbent for water remediation. By varying the solvent-to-modulator ratio in a water-based synthesis path, the particle size of DUT-67 was successfully modulated from 1 μm to 200 nm. Once DUT-67 particles were integrated into the polymeric hydrogel, the composite hydrogel exhibited enhanced mechanical properties after the incorporation of the MOF filler. XPS, NMR, TGA, FTIR, and FT Raman studies confirmed the presence and interaction of the DUT-67 particles with the polymeric chains within the hydrogel network. Adsorption studies of methyl orange, copper(II) ions, and penicillin V on the composite hydrogel revealed a rapid adsorption kinetics and monolayer adsorption according to the Langmuir’s model. The composite hydrogel demonstrated higher adsorption capacities, as compared to the pristine hydrogel, showcasing a synergistic effect, with maximum adsorption capacities of 473 ± 21 mg L−1, 86 ± 6 mg L−1, and 127 ± 4 mg L−1, for methyl orange, copper(II) ions, and penicillin V, respectively. This study highlights the potential of MOF-based composite hydrogels as efficient adsorbents for environmental pollutants and pharmaceuticals.

NiO−CeO2 and NiO−CeO2−ZrO2 catalysts have been synthesized, electrochemically characterized (Mott‐Schottky (MS) measurements and Electrochemical Impedance Spectroscopy), physicochemically characterized (by N2 adsorption, XRD, Transmission Electron Microscopy and XPS) and tested in the N2O assisted ethane oxydehydrogenation. The use of low Zr‐loadings (Zr/Ce=0.1 at. ratio) has led to the optimal results in the ethylene production, improving those obtained by the Zr‐free NiO−CeO2 catalyst. However, high Zr‐loadings have meant a decrease in the olefin production. The catalytic results obtained have been explained considering the amount of oxygen vacancies, the crystalline phases formed and, especially, the nature of the surface Ni species. Importantly, the use of N2O as an oxidizing agent leads to a remarkable improvement in the selectivity to the olefin compared to that obtained employing molecular O2. Then, for a given ethane conversion the selectivity to ethylene is ca. 15 points higher using N2O than using O2. Another additional positive aspect of this NiO−CeO2−ZrO2 catalyst is its high catalytic stability. [ABSTRACT FROM AUTHOR]

Cerium‐containing titania nano‐octahedra (CeTNOh) are obtained by ultrasonication‐hydrothermal synthesis of Ce‐containing titanate nanowires (0.35, 0.46, and 0.70 Ce mol %) from commercial TiO2 (Degussa P25). CeTNOh are tested as photocatalysts to degrade a target pollutant (ciprofloxacin) under simulated solar light and at mild conditions. CeTNOh are anatase polymorphs with increasing crystallite size as Ce content increases. Hydrothermal treatments enhance the specific surface area (SSA) compared to P25, although Ce addition slightly reduces SSA while increasing crystallite size. Electron Microscopy confirms the morphology, although higher Ce levels hinder a full transformation. X‐ray photoemission spectroscopy (XPS) shows the presence of Ce3+/Ce4+ redox pair, promoting electron mobility and Ti‐Ce interactions. Optical and electronic spectroscopy reveals that Ce loading reduces the bandgap from 3.20 to 2.74 eV, extending light absorption into the visible range, thus enhancing the photocatalytic activity. The best sample, CeTNOh0.35, achieved 83% degradation of ciprofloxacin after 360 minutes under solar irradiation, with poor adsorption in the dark period. Higher Ce loadings negatively affect photoactivity by partially covering titania active sites. Reusability tests confirm the stability and efficiency of CeTNOh0.35 over three cycles, highlighting the importance of octahedral morphology in Ce‐containing systems to boost the final photoactivity for water remediation. [ABSTRACT FROM AUTHOR]

An emerging material, cobalt oxide (Co3O4) may be useful for a number of promising technological applications, including energy conversion and storage devices. Among the limiting factors of Co3O4 are its small surface area as well as its poor electrical conductivity. Our study describes the controllable synthesis of Co3O4 nanostructures using a renewable source in the form of potato peel extract, which is an abundant and inexpensive source of starch. Surface active features were observed along with significant changes in structure, crystal orientation, and surface chemical composition. As a result of detailed characterization of phase purity, shape orientation, crystal structure, and surface chemical composition, the as-synthesized Co3O4 nanostructures were fabricated as electrode materials and investigated for supercapacitors and oxygen evolution reactions (OER) applications. The optimized Co3O4 nanostructures comprising 10 mL of potato peel extract have demonstrated a highly improved pseudo-capacitance performance with a specific capacitance of 1453.13Fg− 1 and a specific energy density of 32.29 Wh/Kg at a current density of 1.25 Ag− 1 in 3.0 M KOH electrolytic solution. It was determined that the electrode materials have a cycling stability of 96–99% over 30,000 repeatable cycles with a columbic efficiency of 95–100%, which indicates the high practicality of the electrode materials. The OER performance of 10 mL of potato peel extract assisted Co3O4 nanostructures was also evaluated using 1.0 M KOH. An fabricated Co3O4 nanostructure derived from potato peel extract exhibited an overpotential of 260 mV at 10 mAcm− 2 and a Tafel slope of 72 mV dec− 1 in 1.0 M KOH. Furthermore, the constructed electrode material was extremely durable for a period of 30 h at two different constant-current densities of 20 mAcm− 2 and 40 mAcm− 2. Among the attributes that contribute to the superb performance of the newly developed Co3O4 electrode materials are the fascinating morphology, the reduced size, the enriched active surfaces, and the high degree of compatibility. Overall, the findings of this study establish that potato peel extract can serve as a valuable source of starch for the development of next-generation of electrode materials for efficient energy storage and conversion systems. [ABSTRACT FROM AUTHOR]

Five phyllosilicates (kaolinite, montmorillonite, saponite, sepiolite and palygorskite) have been selected as starting materials for the synthesis of zeolites. Among them, kaolinite and montmorillonite display the lowest Si/Al molar ratio leading to aluminosilicates with high crystallinity. Thus, the hydrothermal treatment under basic conditions forms 4A zeolite when kaolinite is used as starting material while 13X zeolite is obtained when montmorillonite is used as starting material. The microporosity and CO2-adsorption capacity of the prepared zeolites are directly related to its crystallinity. Thus, in order to improve it, raw phyllosilicates were subjected to a microwave-assisted treatment to remove undesired Mg or Fe-species, which have a negative effect in the assembling of the zeolites by hydrothermal basic conditions in a second step. The highest adsorption value was 3.85 mmol/g at 25 °C and 760 mm of Hg for Mont-A-B sample after the consecutive treatments. [ABSTRACT FROM AUTHOR]