Type Of Anion Research Articles

Tracing the Effect of Replacing [Gly]- with [Ala]- and Hydroxylation of [emim]+ on the Fine-Tuning of the Transport Properties of the Corresponding Amino Acid-Based Ionic Liquids Using MD Simulation.

Natural amino acid-based ionic liquids (AAILs) composed of deprotonated amino acids, [AA]-, as anions and hydroxylated imidazolium cations provide an eco-friendly nontoxic IL family with the growing number of chemical and biochemical revolutionary applications. In this paper, the transport properties of four AAILs composed of 1-(2-hydroxyethyl)-3-methylimidazolium ([HOemim]+) and 1-ethyl-3-methylimidazolium ([emim]+) cations with alaninate and glycinate anions were studied by molecular dynamics (MD) simulations. A nonpolarizable all-atom force field with the scaled charge (±0.8e) on each of the ions was applied and compared with the unit charge model in some cases. The tunable effects of the presence of the hydroxyl group in the side chain of the imidazolium cation, the type of amino acid anion, and the varied temperature on the dynamical behavior of AAILs were investigated in detail. The experimentally compatible trends of the simulated ionic self-diffusion coefficients, ionic conductivity, and ionicity were found to be inverse to the viscosity and ionic association of these ILs as [emim][Gly] > [emim][Ala] > [HOemim][Gly] > [HOemim][Ala]. The main reason behind these trends is the higher ability of the hydroxylated cation for the hydrogen-bond formation with [AA]-. The mean square displacement (MSD), self-diffusion, and transference number of imidazolium cations are larger than those of [AA]- anions, except in the case of [HOemim][Gly]. It was found that the activation energy for diffusion of [AA]- is lower than that of [HOemim]+ but higher than that of [emim]+ in [HOemim][AA] and [emim][AA] ILs, respectively. The computed velocity autocorrelation function (VACF) showed that [Gly]-, as the lightest ion, has the shortest mean collision time and velocity randomization time among the ions, especially in the [HOemim][Gly] IL. Replacing [emim]+ with [HOemim]+, similar to the effect of decreasing temperature, causes significant decreasing of the ionic self-diffusion and increasing of the well depth of the first minimum of the ionic VACFs. Current findings show that introducing suitable functional groups in the side chain of imidazolium cations can be a viable approach for efficient engineering design and fine-tuning of the transport properties of these AAILs.

Removal of Pb2+, CrT, and Hg2+ Ions from Aqueous Solutions Using Amino-Functionalized Magnetic Nanoparticles.

In this paper, a circular economy approach with the adsorption and desorption of heavy metal (HM) ions-i.e., lead (Pb2+), chromium (CrT), and mercury (Hg2+)-from aqueous solutions was studied. Specific and selective binding of HM ions was performed on stabilized and amino-functionalized iron oxide magnetic nanoparticles (γ-Fe2O3@NH2 NPs) from an aqueous solution at pH 4 and 7. For this purpose, γ-Fe2O3@NH2 NPs were characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), specific surface area (BET), transmission electron microscopy (TEM), EDXS, and zeta potential measurements (ζ). The effects of different adsorbent amounts (mads = 20/45/90 mg) and the type of anions (NO3-, Cl-, SO42-) on adsorption efficiency were also tested. The desorption was performed with 0.1 M HNO3. The results showed improvement of adsorption efficiency for CrT, Pb2+, and Hg2+ ions at pH 7 by 45 mg of g-Fe2O3@NH2 NPs, and the sequence was as follows: CrT > Hg2+ > Pb2+, with adsorption capacities of 90.4 mg/g, 85.6 mg/g, and 83.6 mg/g, respectively. The desorption results showed the possibility for the reuse of γ-Fe2O3@NH2 NPs with HNO3, as the desorption efficiency was 100% for Hg2+ ions, 96.7% for CrT, and 91.3% for Pb2+.

Anion-Controlled Synthesis of Novel Guanidine-Substituted Oxanorbornanes.

The cycloaddition of simple alkyl-substituted guanidine derivatives is an interesting approach toward polycyclic superbases and guanidine-based organocatalysts. Due to the high nucleophilicity of guanidines, an aza-Michael reaction with dienophiles is more common and presents a huge obstacle in achieving the desired synthetic goal. Our preliminary investigations indicated that the proton could act as a suitable protecting group to regulate the directionality of the reaction. To investigate the role of the protonation state and type of anion, the reactivity of furfuryl guanidines with dimethyl acetylenedicarboxylate was explored. Furfuryl guanidines showed a strong reaction dependence on the nucleophilicity of the counterion and the structure of guanidine. While the reaction of DMAD with the guanidinium halides provided products of an aza-Michael addition, Diels-Alder cycloaddition occurred if non-nucleophilic hexafluorophosphate salts were used. Depending on the structure and the reaction conditions, oxanorbornadiene products underwent subsequent intramolecular cyclization. A tendency toward intramolecular cyclization was interpreted in terms of the pKa of different positions of the guanidine functionality in oxanorbornadienes. New polycyclic guanidines had a slightly decreased pKa in acetonitrile and well-defined geometry suitable for the buildup of selective sensors.

Fucoidan/κ-carrageenan mixed gel: Effect of anions of different valence including chloride, bromide, iodide, sulfate and phosphate

The effects of the differently charged anions, NaCl, NaBr, NaI, Na2SO4, and Na3PO4 on the gel properties and structure of the fucoidan/κ-carrageenan mixed gel (FC) were investigated using the rheometer, texture analyzer, LF-NMR, Cryo-SEM, FT-IR, and XRD. At a certain concentration, Cl− and Br− could stabilize the helical conformation of the gel through electrostatic shielding. The addition of SO42− and PO43− would reduce the strength of the gel. And I− would soften the gel. With increasing anion concentration, the electrostatic repulsion between FUC and KC was gradually enhanced. The FUC dispersions remained liquid after the addition of anions, while FC gelled depending on the type and concentration of anions. The elastic modulus increased with increasing concentration of NaCl and NaBr, but decreased with increasing concentration of NaI, Na2SO4, and Na3PO4. Moreover, the addition of anions promoted the water migration of FC, as reflected by the T23 relaxation time changing from high to low and the significantly higher migration of NaCl and NaBr than NaI and Na2SO4. The pores of the gel microstructure change from disordered to uniform. The FT-IR and XRD results were well related to the structural changes. There is electrostatic repulsion between anion and FC, and the binding ability of FC to monovalent anions and trivalent anions is better than that of divalent anions. Overall, this study could provide a theoretical basis for the design and development of FUC-based gels.

Dynamic stability of a crude oil/brine interface: Effect of anion type

The chemical composition of the aqueous phase plays an essential role in water-based enhanced-oil recovery processes. The aqueous phase ionic profile affects the snap-off response of a crude oil-brine system by linking it to the brine-crude oil interfacial rheology. In this work, we focus on the effect of the anion on the snap-off response. To this end, a sample of crude oil from the Minnelusa Sandstone formation in Wyoming was selected, and several aqueous solutions were prepared with salts containing sodium cation and different anions (chlorides, sulfates, and phosphates) at two ionic strength values, 0.6 M and 6 mM, as cases of high- and low-salinity water. Interfacial tension, interfacial viscoelasticity and interface stability were analyzed as functions of aging time using pendant drop, dilatational rheology, and liquid bridge techniques, respectively. Results show that solutions with higher ionic strength led to the formation of more rigid interfaces, i.e. higher elastic modulus, and faster formation kinetics. In the low-salinity regime, solutions with polyvalent anions produce more viscoelastic interfaces at faster rates than solutions with monovalent anions. Finally, an excellent correlation (R2 greater than 0.97) between the relative stability of the interfacial film, predicted in liquid bridge tests, and the ratio of interfacial tension and interfacial elastic modulus was found.

Humidity Sensors Based on Magnetic Ionic Liquids Blended in Poly(vinylidene fluoride-co-hexafluoropropylene)

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films incorporating 40 wt % of different types of imidazolium ionic liquids (ILs) comprising different magnetic anions (tetrachloroferrate [FeCl4]−, tetrathiocyanatocobaltate [Co(SCN)4]2–, and tetrachlorocobaltate [CoCl4]2−) and imidazolium cation chain lengths (1-butyl-3-methylimidazolium and 1-ethyl-3-methylimidazolium) have been developed for humidity-sensing applications. The influence of the different ILs on the morphology of the IL/PVDF-HFP composites has been evaluated, with a porous structure observed independently of the IL anion type and cation chain length. The inclusion of the ILs into PVDF-HFP induces polymer crystallization into the electroactive β phase, with the increase more noticeable for PVDF-HFP/[Bmim][FeCl4], which reaches a β phase content of 85%. The degree of crystallinity slightly decreases with the incorporation of the filler and the incorporation of [Bmim]2[CoCl4], [Bmim]2[Co(SCN)4], and [Emim]2[Co(SCN)4], leading to a degree of crystallinity between 11 and 13%. A decrease in the thermal stability and yield strength is observed in the hybrid samples with respect to neat PVDF-HFP, with this decrease being more noticeable for the PVDF-HFP/[Bmim]2[Co(SCN)4] samples. Further, the highest magnetization has been obtained for the PVDF-HFP/[Bmim]2[Co(SCN)4] and PVDF-HFP/[Bmim][FeCl4] composites with similar filler concentrations. The suitability of the developed materials for humidity sensing has been evaluated by analyzing the impedance variation with varying relative humidity from 30 to 85%. [Bmim]2[CoCl4]/PVDF-HFP displays the highest relative humidity (RH) sensing response of −2245 ± 240 Ω/RH. Finally, the applicability of the developed hybrid IL/polymer composites has been demonstrated by the development of a real-time breathing monitoring device.

The Rainbow Arching over the Fluorescent Thienoviologen Mesophases.

Thermofluorochromic materials exhibit tunable fluorescence emission on heating or cooling. They are highly desirable for applications ranging from temperature sensing to high-security anti-counterfeiting. Luminescent matrices based on liquid crystals are very promising, particularly those based on liquid crystals with intrinsic fluorescence. However, only a few examples have been reported, suggesting ample margins for development in the field, due to the wide range of fluorophores and supramolecular organizations to be explored. Moreover, thermofluorochromic liquid crystals can be tailored with further functionalities to afford multi-stimuli responsive materials. For the first time, herein we report the thermofluorochromism of thienoviologen liquid crystals, already known to show bulk electrochromism and electrofluorochromism. In particular, we studied their photophysics in the 25 °C-220 °C range and as a function of the length of the N-linear alkyl chains, m (9 ≤ m ≤ 12 C atoms), and the type of anion, X (X = OTs-, OTf-, BF4-, NTf2-). Interestingly, by changing the parameters m, X and T, their fluorescence can be finely tuned in the whole visible spectral range up to the NIR, by switching among different mesophases. Importantly, by fixing the structural parameters m and X, an interesting thermofluorochromism can be achieved for each thienoviologen in a homologous series, leading to a switch of the emitted light from red to green and from white to blue as a consequence of the temperature-induced variation in the supramolecular interactions in the self-assembled phases.

The critical impacts of anion and cosolvent on morpholinium ionic liquid pretreatment for efficient renewable energy production from triticale straw

Morpholinium ionic liquids (ILs) using N-allyl-N-methylmorpholinium ([AMMorph]) cation in combination with acetate ([OAc]), formate ([OFo]), carbonate ([CO3]), and sulfate ([SO4]) anions were used for the pretreatment of triticale straw. The pretreatment was performed with various percentages of IL as well as water and dimethyl sulfoxide (DMSO) as cosolvents. These cosolvents reduced IL consumption and increased the ethanol efficiencies up to 90% and 76% after pretreatment with [AMMorph][OAc] or [AMMorph]2[CO3], respectively, and water cosolvent. Whereas the mixture of water and DMSO resulted in the maximum ethanol yields of 82% and 69% for [AMMorph][OFo] and [AMMorph]2[SO4], respectively. Among the studied IL-cosolvent combinations, the best solvent for the pretreatment of triticale straw was a mixture of [AMMorph][OAc] with 20% water to achieve highest ethanol production. The performance of this IL was further studied in terms of temperature and time, resulting in hydrolysis and ethanol yields of 99% and 94%, respectively. The results revealed that the anion plays a key role in the pretreatment efficiency and the organic anions, i.e., acetate and formate, had better performance in the presence of cosolvent compared with inorganic anions. Moreover, the amount and type of cosolvent for obtaining the highest yields are highly dependent on the anion type.

Salinity and Heavy Metal Tolerance, and Phytoextraction Potential of Ranunculus sceleratus Plants from a Sandy Coastal Beach.

The aim of the present study was to evaluate tolerance to salinity and different heavy metals as well as the phytoextraction potential of Ranunculus sceleratus plants from a brackish coastal sandy beach habitat. Four separate experiments were performed with R. sceleratus plants in controlled conditions: (1) the effect of NaCl gradient on growth and ion accumulation, (2) the effect of different Na+ and K+ salts on growth and ion accumulation, (3) heavy metal tolerance and metal accumulation potential, (4) the effect of different forms of Pb salts (nitrate and acetate) on plant growth and Pb accumulation. A negative effect of NaCl on plant biomass was evident at 0.5 g L-1 Na+ and growth was inhibited by 44% at 10 g L-1 Na+, and this was associated with changes in biomass allocation. The maximum Na+ accumulation (90.8 g kg-1) was found in the stems of plants treated with 10 g kg-1 Na+. The type of anion determined the salinity tolerance of R. sceleratus plants, as Na+ and K+ salts with an identical anion component had a comparable effect on plant growth: nitrates strongly stimulated plant growth, and chloride treatment resulted in slight but significant growth reduction, but plants treated with nitrites and carbonates died within 4 and 5 weeks after the full treatment, respectively. The shoot growth of R. sceleratus plants was relatively insensitive to treatment with Mn, Cd and Zn in the form of sulphate salts, but Pb nitrate increased it. Hyperaccumulation threshold concentration values in the leaves of R. sceleratus were reached for Cd, Pb and Zn. R. sceleratus can be characterized as a shoot accumulator of heavy metals and a hyperaccumulator of Na+. A relatively short life cycle together with a high biomass accumulation rate makes R. sceleratus useful for dynamic constructed wetland systems aiming for the purification of concentrated wastewaters.

CO2 conversion into carbonate using pyridinium-based ionic liquids under mild conditions

A sequence of pyridinium-based acidic-ionic liquids (PyAILs) as dual-functional ILs were synthesized and applied as metal-free, stable and homogeneous catalysts to convert economical, renewable, sustainable and inert CO2 into carbonates. These PyAILs were used to synthesize high-efficiency terminal carbonate from epoxide and greenhouse CO2. Various factors that affected the conversion and selectivity of the reaction including the amount of catalyst, chain length of acidic pendant, anion type, reaction temperature, solvent and reaction time were investigated. The special design of the dual acid-functionalized PyAILs, activated CO2 and epoxide, and the reaction was carried out under mild conditions, solvent-free, low pressure with great TOF and excellent conversion and selectivity above 99% for different types of terminal epoxides. A conceivable reaction mechanism was proposed and it was signified that the carboxylic group and halide ions had a synergetic effect on cyclic carbonates synthesis. In addition, PyAILs can be easily separated by simple extraction from the reaction medium.

Removal of Phosphorus by Ferric Ion-Rich Solutions Prepared Using Various Fe(III)-Containing Minerals

Various biological, chemical, and physical technologies have been studied to effectively remove total phosphorus (T-P) from wastewater. Among them, some mineral suspensions and cations in the aqueous phase have shown great potential for promoting phosphorus removal via chemical precipitation. Herein, we investigated the efficiency of T-P removal using various chemical-based cations (Fe2+, Fe3+, Mg2+, and Al3+); ferric ions (Fe3+) showed the highest T-P-removal efficiency (33.1%), regardless of the type of anion (Cl−, NO3−, and SO42−). To prepare natural Fe3+-rich solutions, three different Fe(III)-rich minerals (hematite, lepidocrocite, and magnetite) were treated with various HCl concentrations to maximize the dissolved Fe3+ amounts. Lepidocrocite in 2 N HCl showed the most effective Fe3+-leaching ability (L-Fe dissolved solution). Almost no significant difference in Fe3+ leaching was observed between HCl and H2SO4, whereas lepidocrocite-2 N H2SO4 showed the highest T-P-removal ability (91.5%), with the formation of amorphous Fe(III)-P precipitates. The L-Fe dissolved solution exhibited a higher T-P-removal efficiency than polyammonium chloride under real wastewater conditions. Our results can provide fundamental knowledge about the effect of cations on T-P removal in wastewater treatment and the feasibility of using the Fe3+ leaching solution prepared from Fe(III)-containing minerals for efficient T-P removal via chemical precipitation.

Copper hexacyanoferrate as a long-life cathode for aqueous aluminum ion batteries

Aqueous aluminum ion batteries (AAIBs) have emerged as promising low-cost and energy-dense alternatives to conventional lithium-ion batteries. However, AAIBs exhibit a poor rate capability and limited cycle life owing to the rapid degradation. In this study, a copper hexacyanoferrate (CuHCFe) electrode was introduced into AAIBs with an aluminum trifluoromethanesulfonate aqueous electrolyte. Common aluminum electrolytes were compared to highlight the effects of anions and pure acid solutions were examined to eliminate the concerns on proton. A reversible capacity of 69.35 mAh/g was obtained at 70 mA/g, with 73% capacity maintained at 50 C, exhibiting excellent rate performance. Furthermore, the types of anions played an important role in the electrochemical performance. With triflate anions, the CuHCFe electrode exhibited remarkable cycling stability with a neglectable capacity loss in 3000 cycles (eight months of continuous testing) at 70 mA/g and 70% retention after 2300 cycles at 350 mA/g. Ex situ characterization revealed that both transition metals in CuHCFe were simultaneously involved in the redox reaction with minimal lattice change upon ion insertion/extraction. The results demonstrate the compatibility and potential of CuHCFe cathodes and aluminum triflate electrolytes for AAIBs, which can promote the development of such batteries for electrochemical energy storage.

Modulating water cluster formation by the hydrophilicity of mixed ionic liquids

Ionic liquids (ILs) have been well known as favorable electrolytes in electrical double layer capacitors (EDLCs) for their unique chemical and thermal properties. However, their stable electrochemical window (EW) will be limited by the adsorption of water. Meanwhile, the state of water molecules in ILs can be modulated by their hydrophilicity, which is adjustable through combining various types of cations and anions. In this work, molecular dynamics simulations were carried out to investigate the behavior and distribution of water molecules in two kinds of ILs 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][TFSI]) and 1-butyl-3-methyl-imidazolium acetate ([BMIM][OAc]), as well as their mixture in different ratios. We found that water molecules tend to aggregate in the hydrophobic [BMIM][TFSI] at a molar concentration as low as 0.1. The introduction of hydrophilic anion of OAc profoundly influences the water aggregation because of their strong interactions with water. It is demonstrated that mixing 20% mol OAc can efficiently stabilize water molecules and maintain the relatively good diffusivity of the hydrophobic IL. The results in this work provide not only valuable information to understand the mechanism of water aggregation in mixing ILs, but also a simple strategy to tune the properties of ILs and improve their performance in EDLCs.

Stable perylene diimide radical/alkylamine complex linked by asymmetric [CO⋯H⋯N]−1 -type strong H-bond and its color switching properties

Radical anions of electron-deficient systems are widely used, but they are easily reoxidized upon exposure to air. Therefore, the stabilization of radical anions under ambient conditions is of great significance, but still remains a scientific challenge. Here, perylene diimide radical anion species is stabilized by an asymmetric anionic low barrier strong hydrogen bond, which is reported firstly. The exchange of a hydrogen atom between one hydrogen atom in nitrogen atom of alkyl amine and the oxygen atom of the carbonyl on perylene diimide radical anion occurs to form such asymmetric anionic type strong hydrogen bond. This bond energy of hydrogen bond is evaluated by the apparent activation energy of thermal decomposition, and it is about 50 kcal/mol. The geometric states in this hydrogen bond depend on external conditions, including solvents and pH value, which will cause the change of their photophysical properties. The hydrogen bond complex shows excellent pH-responsive color switching performance based on the difference in geometric states of this hydrogen bond.

Regenerability of fly‐ash derived zeolite NaP1: Evaluation via copper recovery

AbstractEffective regeneration of adsorbents is considered as one of the essential qualities for commercial use. However, most of the studies have only reported the adsorption properties and overlooked the reuse of adsorbents. In this study, we determined the regenerability and reusability of fly‐ash derived zeolite (FADZ) NaP1. These adsorbents have become popular to remove pollutants from water, including toxic metals, since they are less expensive, compared to their counterparts, and can be synthesized from a waste product. We evaluated the efficiency of copper (Cu2+) ions recovery from water using multiple regeneration solutions due to medium adsorption selectivity towards Cu2+. We determined the time required for the regeneration using acid, base, and salt solutions. The suitable pH and solution while maintaining the structure of the zeolite were studied. Up to 90% recovery was achieved via three successive regenerations, each taking 3 h using 3 M KCl and 3 M NaCl solutions. X‐ray diffraction (XRD) and fluorescence showed changes in structure after regeneration at pH < 5 and contact time <6 h. The desorption kinetics using KCl solutions can be described by pseudo‐second order model. Freundlich model represents the desorption of Cu2+ ions better than the Langmuir model due to regression coefficient (R2) values in the range of 0.998–1.0. Results suggest a strong ion exchange mechanism as the main driving force for desorption. The type of anions (such as Cl− and OH−) in solution influences regeneration in addition to the exchanging cation.

On the impact of the type of anion on the properties of solid-state electrolytes

Solid-state batteries are a valuable option for sustainable energy storage. Their performance is strongly dependent on the ionic conductivity of the solid-state electrolyte (SSE). The mechanism of ion conduction in solid polymer electrolytes has been extensively studied in terms of flexibility of the polymer chains and their interactions with mobile cations that hop between conduction sites carrying the charge. The role of the counterion (i.e. anion) interacting with both the polymer and the cation has not been explored in detail. In this study we show however, that the anion can severely impact the conduction as well. The effect of the anion (I−, SCN−, BF4− and PF6−) on the thermal, structural and electrical properties of a solid polymer electrolyte (15C5BA polymer) was investigated. The results clearly show that the nature of the anions can be used as a parameter to actually tune the properties of the polymer electrolyte.

Tuning Threshold Voltage of Electrolyte-Gated Transistors by Binary Ion Doping.

Electrolyte-gated transistors (EGTs) operating at low voltages have attracted significant attention in widespread applications, including neuromorphic devices, nonvolatile memories, chemical/biosensors, and printed electronics. To increase the practicality of the EGTs in electronic circuits, systematic control of threshold voltage (Vth), which determines the power consumption and noise margin of the circuits, is essential. In this study, we present a simple strategy for systematically tuning Vth to almost half of the operating potential range of the EGT by controlling the electrochemical doping of electrolyte ions into organic p-type semiconductors. The type of anion in the ionogel determines Vth as well as other transistor characteristics, such as the subthreshold swing and mobility, because the positive hole carriers are the majority carriers. More importantly, Vth can be finely controlled by binary anion doping using ionogels with two anions with varying molar fractions at a fixed cation. In addition, the binary anion doping successfully controls the inversion characteristics of ion-gated inverters. As unlimited combinations of ion pairs are possible for ionogels, this study opens a route for controlling the device characteristics to expand the practicality and applicability of ionogel-based EGTs for next-generation ionic/electronic devices.

Synthesis, structure, and Mössbauer spectroscopic studies on the heat-induced solid-phase redox reactions of hexakis(urea-O)iron(III) peroxodisulfate

Anhydrous hexakis(urea-O)iron(III)]peroxydisulfate ([Fe(urea-O)6]2(S2O8)3 (compound 1), and its deuterated form were prepared and characterized with single-crystal X-ray diffraction and spectroscopic (IR, Raman, UV, and Mössbauer) methods. Six crystallographically different urea ligands coordinate via their oxygen in a propeller-like arrangement to iron(III) forming a distorted octahedral complex cation. The octahedral arrangement of the complex cation and its packing with two crystallographically different persulfate anions is stabilized by extended intramolecular (N–H⋯O = C) and intermolecular (N–H⋯O–S) hydrogen bonds. The two types of peroxydisulfate anions form different kinds and numbers of hydrogen bonds with the neighboring [hexakis(urea-O)6iron(III)]3+ cations. There are spectroscopically six kinds of urea and three kinds (2 + 1) of persulfate ions in compound 1, thus to distinguish the overlapping bands belonging to internal and external vibrational modes, deuteration of compound 1 and low-temperature Raman measurements were also carried out, and the bands belonging to the vibrational modes of urea and persulfate ions have been assigned. The thermal decomposition of compound 1 was followed by TG-MS and DSC methods in oxidative and inert atmospheres as well. The decomposition starts at 130 °C in inert atmosphere with oxidation of a small part of urea (~ 1 molecule), which supports the heat demand of the transformation of the remaining urea into ammonia and biuret/isocyanate. The next step of decomposition is the oxidation of ammonia into N2 along with the formation of SO2 (from sulfite). The main solid product proved to be (NH4)3Fe(SO4)3 in air. In inert atmosphere, some iron(II) compound also formed. The thermal decomposition of (NH4)3Fe(SO4)3 via NH4Fe(SO4)2 formation resulted in α-Fe2O3. The decomposition pathway of NH4Fe(SO4)2, however, depends on the experimental conditions. NH4Fe(SO4)2 transforms into Fe2(SO4)3, N2, H2O, and SO2 at 400 °C, thus the precursor of α-Fe2O3 is Fe2(SO4)3. Above 400 °C (at isotherm heating), however, the reduction of iron(III) centers was also observed. FeSO4 formed in 27 and 75% at 420 and 490 °C, respectively. FeSO4 also turns into α-Fe2O3 and SO2 on further heating.Graphical abstract

ANALYSIS OF THE CATIONIC-ANIONIC COMPOSITION OF FEED

When compiling diets for productive animals, one of the indicators taken into account is the cationanion balance, which is calculated based on the content of sodium and potassium cations and sulfate and chloride anions. The cationic-anionic composition of feed is very diverse. The lack or excess of one or another cation or anion in feed can lead to disruption of metabolic processes and various diseases of non-infectious etiology.The aim of the work was to quantify and analyze the cationanion composition of feed for productive animals by capillary electrophoresis.The research was carried out in the conditions of the educational and research center for the examination of food and animal feed of the St. Petersburg State University of Veterinary Medicine. 76 samples of various feeds for productive animals were used as research materials: 19 samples of grass flour, cake, mixed feeds for cattle.The study of the cationic composition of the studied feed samples was carried out, guided by the methodology M 04-65-2010 «Feed, compound feed and raw materials for their production. The method of measuring the mass fraction of ammonium, potassium, sodium, magnesium and calcium cations by capillary electrophoresis using the capillary electrophoresis system «Kapel», and anionic composition – according to the method M 04 -73-2011 «Feed, compound feed and raw materials for their production. The method of measuring the mass fraction of water-soluble forms of chloride, sulfate, nitrate and phosphate ions by capillary electrophoresis using the capillary electrophoresis system «Kapel» (GC «LUMEX»).Thus, analyzing the results obtained, it was found that in all samples of feed for productive animals, the mass fraction of cations and anions varied depending on the type of cation or anion and feed.Determination of the cationic-anionic composition of feed is a necessary condition for the formation of a full-fledged diet that provides the body of productive animals with nutrients, which is especially important in modern conditions of intensification of animal husbandry and agricultural development.

Study on Synergistic Demulsification Mechanism of Microwaves and Ionic Liquids on Heavy Oil Emulsions

Summary Heavy oil-in-water (O/W) emulsions must be treated before refinement and transportation, and microwave and ionic liquid (IL) synergistic effects are stable, efficient, and environmentally friendly methods of demulsification. In this study, the synergistic effects of various IL anion and cation types and concentrations upon microwave emulsion demulsification were investigated. The interfacial tension (IFT) and zeta potential of the ILs and the distribution of oil droplets were measured before and after microwave radiation using a spinning drop tensiometer, zeta potential analyzer, and biological microscope to elucidate the synergistic mechanism of microwave and IL demulsification. The results indicate that microwave radiation parameters that are set too high or low can have an inhibitory effect on demulsification. When [C16MIM]Br with a concentration of 1 mmol/L was used as the IL, and the microwave radiation parameters were set to 300 W for 30 seconds, the demulsification efficiency reached 89.29%, which was 3.23 times and 2.08 times higher than the individual demulsification efficiency of microwave radiation and IL, respectively. This study provides a novel approach for examining high-performance demulsification, and it extends the applicability of microwave-IL synergy.