Characterization of Hydrothermally Decomposed and Synthesized CaCO3 Reinforcement from Dead Snail Shells.

The development of new materials from marine resources presents a significant challenge due to the complexity of the associated materials and biology technologies. During this work, the snail shell, which naturally increases in thickness over time to protect the snail, has been identified as one of them. In this study, we investigated the use of powdered snail shells as a potential alternative to ceramics in the creation of customized composites. Our main objective is to explore the hydrothermal decomposition of the snail shell powder to remove undesirable components. To achieve this, we crushed and ground-washed dead snail shells and subjected them to hydrothermal decomposition using an autoclave and furnace at a temperature of 200, 220, 250, or 300 °C. We then analyzed the resulting samples using scanning electron microscope/energy-dispersive X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) techniques to determine changes in their composition and structure. Our findings demonstrate that all samples contained the elements Ca, C, and O, as confirmed by SEM/EDS results. XRD results show that hydrothermal decomposition at 250 °C led to good crystallization with maximum peak intensities observed at various diffraction angles. This indicates that the resulting material may have promising properties for use in composite materials. Overall, our study provides valuable insights into the use of snail shell powder as a potential material source for customized composites. Future studies could explore the optimization of the hydrothermal decomposition process and investigate the mechanical properties of the resulting materials to further develop this promising avenue of research.

Tuneable-by-design copper oxide nanoparticles in ionic liquid nanofluids.

In this study, copper oxide nanoparticles (CuO-NPs) were synthesised in an ionic liquid, [C2MIm][CnHnCO2], and the respective copper(II) carboxylate precursors. Heating the solution to 120 °C caused a colour change from blue to red, indicating a change in copper salt coordination and nanoparticle formation. Crystallography and UV-Vis spectroscopy were used to monitor the transition upon temperature changes. The particle formation was characterised using TEM and SWAXS analyses. The results showed that different anion chain lengths led to different particle sizes. When using copper(II) acetate precursors, the transformation resulted in CuO(I,II) clusters (<1 nm), depending on the imidazolium-based cation used. However, using a copper(II) octanoate precursor, small CuO-NPs in the range of 10-25 nm were formed, while larger CuO-NPs were obtained using a copper(II) butanoate precursor in the range of 10-61 nm.

The Prediction of Cu(II) Adsorption Capacity of Modified Pomelo Peels Using the PSO-ANN Model.

It is very well known that traditional artificial neural networks (ANNs) are prone to falling into local extremes when optimizing model parameters. Herein, to enhance the prediction performance of Cu(II) adsorption capacity, a particle swarm optimized artificial neural network (PSO-ANN) model was developed. Prior to predicting the Cu(II) adsorption capacity of modified pomelo peels (MPP), experimental data collected by our research group were used to build a consistent database. Then, a PSO-ANN model was established to enhance the model performance by optimizing the ANN's weights and biases. Finally, the performances of the developed ANN and PSO-ANN models were deeply evaluated. The results of this investigation revealed that the proposed hybrid method did increase both the generalization ability and the accuracy of the predicted data of the Cu(II) adsorption capacity of MPPs when compared to the conventional ANN model. This PSO-ANN model thus offers an alternative methodology for optimizing the adsorption capacity prediction of heavy metals using agricultural waste biosorbents.

Assessment of Cu(II) Removal from Aqueous Solutions by Modified Pomelo Peels: Experiments and Modelling.

In this study, low-cost pomelo peel wastes were used as a bio-sorbent to remove copper ions (e.g., Cu(II)) from aqueous solutions. Prior to testing its Cu(II) removal capability, the structural, physical and chemical characteristics of the sorbent were examined by scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, and Brunauer-Emmett-Teller (BET) surface area analysis. The impacts of the initial pH, temperature, contact time and Cu(II) feed concentration on the Cu(II) biosorption using modified pomelo peels were then assessed. Thermodynamic parameters associated to the biosorption clearly demonstrate that this biosorption is thermodynamically feasible, endothermic, spontaneous and entropy driven. Furthermore, adsorption kinetic data were found to fit very well with the pseudo-second order kinetics equation, highlighting that this process is driven by a chemical adsorption. Finally, an artificial neural network with a 4:9:1 structure was then established for describing the Cu(II) adsorption using modified pomelo peels with R2 values close to 0.9999 and to 0.9988 for the training and testing sets, respectively. The results present a big potential use of the as-prepared bio-sorbent for the removal of Cu(II), as well as an efficient green technology for ecological and environmental sustainability.

Efficient Synthesis of 1H-Benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-one Derivatives Using Ag2CO3/TFA-Catalyzed 6-endo-dig Cyclization: Reaction Scope and Mechanistic Study.

A small library of 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-one derivatives was prepared in good to excellent yields, involving a Ag2CO3/TFA-catalyzed intramolecular oxacyclization of N-Boc-2-alkynylbenzimidazole substrates. In all experiments, the 6-endo-dig cyclization was exclusively achieved since the possible 5-exo-dig heterocycle was not observed, indicating the high regioselectivity of this process. The scope and limitations of the silver catalyzed 6-endo-dig cyclization of N-Boc-2-alkynylbenzimidazoles as substrates, bearing various substituents, were investigated. While ZnCl2 has shown limits for alkynes with an aromatic substituent, Ag2CO3/TFA demonstrated its effectiveness and compatibility regardless of the nature of the starting alkyne (aliphatic, aromatic or heteroaromatic), providing a practical regioselective access to structurally diverse 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-ones in good yields. Moreover, the rationalization of oxacyclization selectivity in favor of 6-endo-dig over 5-exo-dig was explained by a complementary computational study.

A Comprehensive Formulation of Aqueous Electrolytes for Low-Temperature Supercapacitors.

Safer-by-design and sustainable energy storage devices are envisioned to be among the required 2.0 solutions to satisfy the fast growing energy demands. Responding to this evolution cannot be freed from a global and synergetic approach to design the requisite electrolytes taking into account the toxicity, the eco-compatibility and the cost of their constituents. To target low-temperature applications, a non-toxic and cost-efficient eutectic system comprising LiNO3 in water with 1,3-propylene glycol as co-solvent was selected to design a ternary electrolyte with a wide liquid range. By using this electrolyte in an electrochemical double-layer capacitor (EDLC), the operating voltage of the device reaches an optimum of 2.0 V at -40 °C over more than 100 h of floating. Moreover, after being set up at 20 °C, the temperature resilience of the capacitance is near total, demonstrating thus a promising feature related to the suitable thermal and electrochemical behaviours of the tested EDLC devices.

Stepwise synthesis of 2,6-difunctionalized ethyl pyrazolo[1,5-a]pyrimidine-3-carboxylate via site-selective cross-coupling reactions: experimental and computational studies.

A variety of novel disubstituted 2-(alknyl, aryl and arylamine)-6-alkynylpyrazolo[1,5-a]pyrimidine derivatives was prepared via sequential site-selective cross-coupling reactions from 2,6-dibromopyrazolo[1,5-a]pyrimidine 3. The regio-controlled Sonogashira-type coupling of 3 with a wide range of terminal alkynes proceeded smoothly with excellent selectivity in favor of the C6-position through careful adjustment of the coupling conditions, followed by the subsequent introduction of alkynyl, aryl or arylamine groups at the C2-position via the Sonogashira, Suzuki-Miyaura and Buchwald-Hartwig coupling reactions, respectively. These promising results allow for further use and diversification of the chemically and biologically interesting pyrazolo[1,5-a]pyrimidine scaffold. In addition, computational studies were conducted to provide explanations for the origin of regioselectivity.

Alternative Solvents for the Biorefinery of Spirulina: Impact of Pretreatment on Free Fatty Acids with High Added Value.

The growing demand for molecules of interest from microalgal biomass, such as phycobiliproteins, has led to an accumulation of unused by-products. For example, phycocyanin, obtained by the extraction of Spirulina, generated cakes rich in non-polar molecules of interest, such as free fatty acids (FFAs). These FFAs were generally considered as markers of lipidome degradation, but represented a relevant alternative to topical antibiotics, based on a biomimetic approach. In order to develop a sustainable Spirulina biorefinery scheme, different pretreatments and alternative solvents were screened to identify the best combination for the valorization of FFAs. Thus, five pre-treatments were studied including a phycocyanin extraction by-product. The following three biobased solvents were selected: ethyl acetate (EtOAc), dimethyl carbonate (DMC) and a fatty acid-based natural deep eutectic solvent (NaDES). The pigment and fatty acid profiles were established by spectroscopic and chromatographic approaches. NaDES demonstrated superior extraction capacity and selectivity compared to other biobased solvents, regardless of pretreatment. In contrast, EtOAc and DMC showed a greater diversity of FFAs, with a predominance of polyunsaturated fatty acids (PUFAs). The by-product has also been highlighted as a relevant raw material facilitating the recovery of FFAs. These results pave the way for a green biorefinery of the lipid fraction and phycobiliproteins of microalgae.

A study of changes in the heat capacity of carbon nanotube-based ionanofluids prepared from a series of imidazolium ionic liquids.

Ionanofluids (INFs), nanoparticles dispersed into a base fluid, e.g. an ionic liquid, are a novel class of alternative heat transfer fluids. Addition of nanoparticles to a base ionic liquid is the prime reason for an enhancement in the thermophysical properties of ionanofluids. However, due to very limited research on ionanofluids, further studies are required to understand changes in the isobaric heat capacity of ionanofluids as a function of size of cations of the base ionic liquid structure and concentration of nanoparticles. Herein, isobaric heat capacity was measured as a function of temperature for the prepared ionanofluid samples from a series of imidazolium ionic liquids and multi walled carbon nanotubes (MWCNTs). Moreover, the influence of the size of cations on the isobaric heat capacity enhancement mechanism and the stability of ionanofluid samples was studied. Furthermore, experimental isobaric heat capacity data were assessed by a novel non-statistical data analysis method named mathematical gnostics (MG). MG marginal analysis was used to evaluate the most probable values from the measured data set. A robust linear regression along a gnostic influence function was also used to find the best fit to correlate the measured data.

Combined Superbase Ionic Liquid Approach to Separate CO2 from Flue Gas.

Superbase ionic liquids (ILs) with a trihexyltetradecylphosphonium cation and a benzimidazolide ([P66614][Benzim]) or tetrazolide ([P66614][Tetz]) anion were investigated in a dual-IL system allowing the selective capture and separation of CO2 and SO2, respectively, under realistic gas concentrations. The results show that [P66614][Tetz] is capable of efficiently capturing SO2 in preference to CO2 and thus, in a stepwise separation process, protects [P66614][Benzim] from the negative effects of the highly acidic contaminant. This results in [P66614][Benzim] maintaining >53% of its original CO2 uptake capacity after 30 absorption/desorption cycles in comparison to the 89% decrease observed after 11 cycles when [P66614][Tetz] was not present. Characterization of the ILs post exposure revealed that small amounts of SO2 were irreversibly absorbed to the [Benzim]- anion responsible for the decrease in CO2 capacity. While optimization of this dual-IL system is required, this feasibility study demonstrates that [P66614][Tetz] is a suitable sorbent for reversibly capturing SO2 and significantly extending the lifetime of [P66614][Benzim] for CO2 uptake.

A Ag2CO3/TFA-catalyzed intramolecular annulation approach to imidazo[1,2-c][1,3]oxazin-5-one derivatives.

A series of 2,7-disubstituted 3-methylimidazo[1,2-c][1,3]oxazin-5-ones were synthesized in good yields via Ag2CO3/TFA-mediated intramolecular annulation of N-Boc-2-alkynyl-4-bromo(alkynyl)-5-methylimidazoles. This methodology was carried out in the presence of a catalytic amount of silver carbonate and trifluoroacetic acid in dichloroethane at 60 °C. In all experiments, only the six-membered ring product was obtained since the possible five-membered compound was not observed, proving the high regioselectivity of this approach. A complementary computational study was performed in order to rationalize the mechanism of 6-endo-dig heterocycle formation. In addition, 2-bromo-3-methyl-7-phenylimidazo[1,2-c][1,3]oxazin-5-one was used as a building block to synthesize a small library of new 2-substituted imidazo[1,2-c][1,3]oxazin-5-one derivatives through the Suzuki, Sonogashira and Heck cross coupling reactions.

Good Reporting Practice for Thermophysical and Thermochemical Property Measurements (IUPAC Technical Report).

Scientific projects frequently involve measurements of thermophysical, thermochemical, and other related properties of chemical compounds and materials. These measured property data have significant potential value for the scientific community, but incomplete and inaccurate reporting often hampers their utilization. The present IUPAC Technical Report summarizes the needs of chemical engineers and researchers as consumers of these data and shows how publishing practices can improve information transfer. In the Report, general principles of Good Reporting Practice are developed together with examples illustrating typical cases of reporting issues. Adoption of these principles will improve the quality, reproducibility, and usefulness of experimental data, bring a better level of consistency to results, and increase the efficiency and impact of research. Closely related to Good Reporting Practice, basic elements of Good Research Practice are also introduced with a goal to reduce the number of ambiguities and unresolved problems within the thermophysical property data domain.

Combined Experimental and Theoretical Study of the Competitive Absorption of CO2 and NO2 by a Superbase Ionic Liquid.

A superbase ionic liquid (IL), trihexyltetradecylphosphonium benzimidazolide ([P66614][Benzim]), is investigated for the capture of CO2 in the presence of NO2 impurities. The effect of the waste gas stream contaminant on the ability of the IL to absorb simultaneously CO2 is demonstrated using novel measurement techniques, including a mass spectrometry breakthrough method and in situ infrared spectroscopy. The findings show that the presence of an industrially relevant concentration of NO2 in a combined feed with CO2 has the effect of reducing the capacity of the IL to absorb CO2 efficiently by ∼60% after 10 absorption-desorption cycles. This finding is supported by physical property analysis (viscosity, 1H and 13C NMR, and X-ray photoelectron spectroscopy) and spectroscopic infrared characterization, in addition to density functional theory (DFT) calculations, to determine the structure of the IL-NO2 complex. The results are presented in comparison with another flue gas component, NO, demonstrating that the absorption of NO2 is more favorable, thereby hindering the ability of the IL to absorb CO2. Significantly, this work aids understanding of the effects that individual components of flue gas have on CO2 capture sorbents, through studying a contaminant that has received limited interest previously.

Selective adsorptive separation of cyclohexane over benzene using thienothiophene cages.

The selective separation of benzene (Bz) and cyclohexane (Cy) is one of the most challenging chemical separations in the petrochemical and oil industries. In this work, we report an environmentally friendly and energy saving approach to separate Cy over Bz using thienothiophene cages (ThT-cages) with adaptive porosity. Interestingly, cyclohexane was readily captured selectively from an equimolar benzene/cyclohexane mixture with a purity of 94%. This high selectivity arises from the C-H⋯S, C-H⋯π and C-H⋯N interactions between Cy and the thienothiophene ligand. Reversible transformation between the nonporous guest-free structure and the host-guest assembly, endows this system with excellent recyclability with minimal energy requirements.

Type 3 Porous Liquids for the Separation of Ethane and Ethene.

We assess the potential for formulating a porous liquid that could be used as a selective solvent for the separation of ethane and ethene. Ethane-ethene separation is performed on very large scales by cryogenic distillation, but this uses large amounts of energy. Solvents that are selective to ethane or ethene could potentially enable more efficient liquid-based separation processes to be developed, but to date such solvents have been elusive. Here, Type 3 porous liquids, which consist of microporous solids dispersed in size-excluded liquid phases, were tailored toward the separation of ethane and ethene. A high selectivity for ethene over ethane (25.6 at 0.8 bar) and a high capacity was achieved for zeolite AgA dispersed in an Ag-containing ionic liquid. Unusually for liquid phases, the selectivity for ethane over ethene (2.55 at 0.8 bar) could also be achieved using either the metal-organic framework (MOF) Cu(Qc)2 (Qc = quinoline-5-carboxylate) dispersed in sesame oil or ZIF-7 in sesame oil, the latter showing gated uptake. The efficiency of the Cu(Qc)2 synthesis was increased by developing a mechanochemical method. The regeneration of Cu(Qc)2 in sesame oil and ZIF-7 in sesame oil was also demonstrated, suggesting that these or similar porous liquids could potentially be applied in cyclic separation processes.

Reference Materials for Phase Equilibrium Studies. 1. Liquid-Liquid Equilibria (IUPAC Technical Report).

This article is the first of three projected IUPAC Technical Reports resulting from IUPAC Project 2011-037-2-100 (Reference Materials for Phase Equilibrium Studies). The goal of that project was to select reference systems with critically evaluated property values for the validation of instruments and techniques used in phase equilibrium studies for mixtures. This Report proposes seven systems for liquid-liquid equilibrium studies, covering the four most common categories of binary mixtures: aqueous systems of moderate solubility, non-aqueous systems, systems with low solubility, and systems with ionic liquids. For each system, the available literature sources, accepted data, smoothing equations, and estimated uncertainties are given.

Industrial Applications of Ionic Liquids.

Since their conception, ionic liquids (ILs) have been investigated for an extensive range of applications including in solvent chemistry, catalysis, and electrochemistry. This is due to their designation as designer solvents, whereby the physiochemical properties of an IL can be tuned for specific applications. This has led to significant research activity both by academia and industry from the 1990s, accelerating research in many fields and leading to the filing of numerous patents. However, while ILs have received great interest in the patent literature, only a limited number of processes are known to have been commercialised. This review aims to provide a perspective on the successful commercialisation of IL-based processes, to date, and the advantages and disadvantages associated with the use of ILs in industry.

Guidelines for designing highly concentrated electrolytes for low temperature applications.

The redefinition of the commonly named "water-in-salt" clarifies the operating temperatures of the state-of-the-art LiTFSI-based aqueous solutions. An in-depth study shows its mismatch for low temperature applications. In contrast, the recommended strategy is to design an electrolyte with an invariant composition, as exemplified by the eutectic water/LiNO3 that is able to electrochemically cycle down to -23 °C.

Phosphoric acid-mediated green preparation of regenerated cellulose spheres and their use for all-cellulose cross-linked superabsorbent hydrogels.

With the growing environmental concerns and an emergent demand, a growing attention is turned to eco-friendly superabsorbent hydrogels instead of synthetic counterparts. Hydrogels based on cellulose derivatives can absorb and retain a huge amount of water in the interstitial sites of their structures, stimulating their uses in various useful industrial purposes. In this work, cross-linked superabsorbent composite hydrogel films (CHF) were designed, manufactured and characterized, by taking advantage of the combination of carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC) and newly developed regenerated cellulose (RC) spheres. RC with sphere-like shape was successfully prepared using a green method based on cold phosphoric acid-mediated dissolution of microcrystalline cellulose (MCC) followed by regeneration process using water as anti-solvent. Prior to be used, the morphological and structural properties of RC spheres, with an average diameter of 477 ± 270 nm, were examined by SEM, AFM, XRD, FTIR and TGA techniques. CHF crosslinked with citric acid were, in fact, prepared by solvent casting method with different RC weight fractions (i.e. 0, 2.5, 5, 10 and 15 wt%), then the crosslinking reaction was triggered by thermal treatment at 80 °C during 8 h. Prepared CHF were then characterized in terms of their structural, thermal, tensile and transparency properties. Swelling tests were carried at three different aqueous media (i.e. with a pH = 3, 6.4 or 11) to evaluate the water retention capacity of hydrogel films, as well as, the pH effect on their swelling and hydrolytic degradation properties. Collected results reveal that CHF with low RC content (i.e. RC weight fraction of 2.5 or 5 wt%) have the best tensile and swelling properties, with a tensile strength and a swelling capacity (at pH = 6.4) up to 95 MPa and 4000%, respectively.

Phenylacetonitrile (C6H5CH2CN) Ionic Liquid Blends as Alternative Electrolytes for Safe and High-Performance Supercapacitors.

The increasing need in the development of storage devices is calling for the formulation of alternative electrolytes, electrochemically stable and safe over a wide range of conditions. To achieve this goal, electrolyte chemistry must be explored to propose alternative solvents and salts to the current acetonitrile (ACN) and tetraethylammonium tetrafluoroborate (Et4NBF4) benchmarks, respectively. Herein, phenylacetonitrile (Ph-ACN) has been proposed as a novel alternative solvent to ACN in supercapacitors. To establish the main advantages and drawbacks of such a substitution, Ph-ACN + Et4NBF4 blends were formulated and characterized prior to being compared with the benchmark electrolyte and another alternative electrolyte based on adiponitrile (ADN). While promising results were obtained, the low Et4NBF4 solubility in Ph-ACN seems to be the main limiting factor. To solve such an issue, an ionic liquid (IL), namely 1-ethyl-3-methylimidazolium bis [(trifluoromethyl)sulfonyl] imide (EmimTFSI), was proposed to replace Et4NBF4. Unsurprisingly, the Ph-ACN + EmimTFSI blend was found to be fully miscible over the whole range of composition giving thus the flexibility to optimize the electrolyte formulation over a large range of IL concentrations up to 4.0 M. The electrolyte containing 2.7 M of EmimTFSI in Ph-ACN was identified as the optimized blend thanks to its interesting transport properties. Furthermore, this blend possesses also the prerequisites of a safe electrolyte, with an operating liquid range from at least -60 °C to +130 °C, and operating window of 3.0 V and more importantly, a flash point of 125 °C. Finally, excellent electrochemical performances were observed by using this electrolyte in a symmetric supercapacitor configuration, showing another advantage of mixing an ionic liquid with Ph-ACN. We also supported key structural descriptors by density functional theory (DFT) and COnductor-like Screening Model for Real Solvents (COSMO-RS) calculations, which can be associated to physical and electrochemical properties of the resultant electrolytes.