Analysis of Steroid Hormones in Water Using Palmitate-Coated Magnetite Nanoparticles Solid-Phase Extraction and Gas Chromatography–Tandem Mass Spectrometry

A new extractive method based on magnetic solid–phase extraction using palmitate-coated magnetite nanoparticles coupled with gas chromatography-tandem mass spectrometry was developed for the extraction of estrone, androstenedione and progesterone hormones from water. The amount of nanoparticles and extraction time were optimized applying an experimental design to estimate simultaneously their influence on the recoveries. Results showed that the extraction efficiency was highly affected by the addition of salt and acetonitrile was the solvent used to elute the analytes from the nanoparticles. Derivatization via enolization of ketone group was carried out in the extract for the simultaneous derivatization of hydroxyl and ketone groups of steroid hormones previously to their chromatographic analysis. The extraction efficiencies of the nanoparticles were studied spiking at four concentration levels and recoveries from 94.6 to 109.7 % were obtained. The limits of detection ranged from 4 to 8 ng L^?1. The developed method provided a preconcentration factor of 100. The present work shows that palmitate-coated magnetite nanoparticles have good applicability for the extraction of natural estrogenic hormones that could be pollutants in real water samples.     

Analysis of Steroid Hormones in Water Using Palmitate-Coated Magnetite Nanoparticles Solid-Phase Extraction and Gas Chromatography–Tandem Mass Spectrometry

A new extractive method based on magnetic solid–phase extraction using palmitate-coated magnetite nanoparticles coupled with gas chromatography-tandem mass spectrometry was developed for the extraction of estrone, androstenedione and progesterone hormones from water. The amount of nanoparticles and extraction time were optimized applying an experimental design to estimate simultaneously their influence on the recoveries. Results showed that the extraction efficiency was highly affected by the addition of salt and acetonitrile was the solvent used to elute the analytes from the nanoparticles. Derivatization via enolization of ketone group was carried out in the extract for the simultaneous derivatization of hydroxyl and ketone groups of steroid hormones previously to their chromatographic analysis. The extraction efficiencies of the nanoparticles were studied spiking at four concentration levels and recoveries from 94.6 to 109.7 % were obtained. The limits of detection ranged from 4 to 8 ng L⁻¹. The developed method provided a preconcentration factor of 100. The present work shows that palmitate-coated magnetite nanoparticles have good applicability for the extraction of natural estrogenic hormones that could be pollutants in real water samples.

     

Designing Metal–Organic Framework (MOF) Membranes for Isomer Separation

Membrane-based separation has the merit of low carbon footprint. In this study, the pore size of metal–organic framework (MOF) membranes is rationally designed for discriminating various pairs of hydrocarbon isomers. Specifically, Zr-MOF UiO-66 (UiO stands for University of Oslo) membranes are developed for separating p/o-xylene due to their proper pore size. For n-hexane/2-methylpentane separation, the functional groups and proportion of the ligands in UiO-66 are gradually adjusted to effectively regulate the pore size, and UiO-66-33Br membranes are constructed. In addition, relying on the utilization of ligands with shorter length, MOF-801 membranes with smaller pore size are fabricated for n/i-butane separation.     

Factors Affecting the Droplet Size of Water‐in‐Oil Emulsions (W/O) and the Oil Globule Size in Water‐in‐Oil‐in‐Water Emulsions (W/O/W)

Multiple emulsions of the W₁/O/W₂ type are promising tools for encapsulating bioactive ingredients in the inner aqueous droplets. It is necessary, however, to control the factors influencing their encapsulation efficiency. One important factor is the particle size because it determines the surface area available for mass transport. Because of the coexistence of water and oil droplets in multiple emulsions, there are numerous factors that have an impact on particle size, for example, oil phase composition, interfacial properties, and viscosity of the phases. The purpose of this study was to systematically investigate the effect of these factors on particle sizes in multiple emulsions.     

Phase Behavior of Poly(Oxyethylene)–Poly(Oxypropylene)–Poly(Oxyethylene) Block Copolymer in Water and Water–C12EO5 Systems

Abstract

The binary phase diagram of a triblock copolymer poly(oxyethylene) (PEO) poly(oxypropylene) (PPO) poly(oxyethylene) (PEO), (PEO)₃₇(PPO)₅₈(PEO)₃₇ or P105 in water and the ternary system of P105, water, and pentaoxyethylene dodecyl ether (C₁₂EO₅) has been studied to understand the miscibility of a small amphiphile, C₁₂EO₅ and a copolymer, as well as the mixing effect on the formed liquid crystalline structures. Phase diagrams, small angle x‐ray scattering (SAXS) and differential scanning calorimetry (DSC) were used to characterize these systems. The phase diagram of the binary system is presented together with the characteristic parameters for founded phases, namely, cubic, hexagonal, and lamellar phases. In the ternary system it was found that the small amphiphile and the block copolymer, despite having very different chain lengths are essentially miscible forming single phases. A large amount of C₁₂EO₅ can be solubilized in the P105 aggregates whereas P105 is most difficult to dissolve in the C₁₂EO₅ aggregates because of the difference in the molecular size. The copolymer is practically insoluble in the lamellar phase of C₁₂EO₅ due to the packing constraint. Hence, two lamellar phases coexist in a surfactant‐rich region, at W _s  = 0.66, where W _s is the weight fraction of the total amphiphile in the system. This indicates that the thickness of the lipophilic part of the C₁₂EO₅ lamellar phase is too small to allocate the large lipophilic chain of the P105 triblock copolymer.     

Removal of Lead(II), Cadmium(II), and Arsenic(III) from Aqueous Solution Using Magnetite Nanoparticles Prepared by Green Synthesis with Box–Behnken Design

Two types of magnetite (Fe₃O₄) nanoparticles were investigated as adsorbents for the simultaneous removal of Pb(II), Cd(II), and As(III) metal ions from aqueous solution. Magnetite nanoparticles were prepared by two synthesis procedures, both using water as solvent, and are referred to as conventional Fe₃O₄ nanoparticles and green Fe₃O₄ nanoparticles. The latter used Citrus limon (lemon) aqueous peel extract as the surfactant. Box–Behnken experimental design was used to investigate the effects of parameters such as initial concentration (20–150?mg?L^?1), pH (2–9), and biomass dosage (1–5?g?L^?1) on the removal of Pb(II), Cd(II), and As(III) ions. The optimum parameters for removal of the studied metal ions from aqueous solutions, including the initial ion concentration (20?mg?L^?1), pH (5.5) and adsorbent dose (5?g?L^?1), were determined. The pseudosecond-order model exhibited the best fit for the kinetic studies, while adsorption equilibrium isotherms were best described by Langmuir and Freundlich models. The optimum conditions were applied for the treatment wastewater. The removal efficiencies of Pb(II), Cd(II), and As(III) using the conventional and green synthesized Fe₃O₄ nanoparticles were 59.4?±?4.3, 18.7?±?1.9 and 17.5?±?1.6, and 98.8?±?5.6, 46.0?±?1.3, and 48.2?±?2.6%, respectively. These results demonstrate the potential of magnetite nanoparticles synthesized using C. limon peel extract as highly efficient adsorbents for the removal of Pb(II), Cd(II), and As(III) ions from aqueous solution.     

Facile Synthesis of Functionalized Bis(arylethynyl)benzene Derivatives via Sila–Sonogashira Reaction

This article describes a facile synthesis of a new series of symmetrical bis(arylethynyl)benzene derivatives via a one-pot coupling reaction between trialkylsilyl protected arylalkynyes and aryldihalides bearing both electron-withdrawing (EW) and electron-donating groups (ED) in the presence of PdCl₂(PPh₃)₂(5%) / CuI/tetrabutylammonium fluoride / triethylamine / tetrahydrofuran (sila–Sonogashira reaction) at room temperature.     

Recovery and pre-concentration of gold onto poly((N-(Hydroxymethyl)methacrylamide)–1-allyl-2-thiourea) hydrogels synthesized by gamma radiation

Poly((N-(Hydroxymethyl)methacrylamide)–1-allyl-2-thiourea) hydrogels, Poly(NHMMA–ATU), were synthesized by gamma radiation using ⁶⁰Co γ source at different irradiation doses and different ATU content in the irradiated monomer mixture. The swellability of the synthesized hydrogels was changed by irradiation doses and by the content of ATU in the irradiated mixture. These hydrogels were used for the specific gold recovery and pre-concentration from single gold ion solutions and from different natural samples. It has been observed that gold adsorption capacity onto the hydrogels was high at low pHs and reached maximum value at pH = 0.5. Adsorption capacity of the hydrogels for gold at pH = 0.5 was found to be about 698 mg g^− 1 dry hydrogels. Adsorption equilibrium time of gold ions onto the hydrogels was found to be very short and also these hydrogels were showed extremely high selectivity to the gold ions in acidic media when the concentration of the other metal ions were extremely higher than gold. Because of the high specificity of these hydrogels to gold beside the other metal ions at low pHs, all matrix effects were easily eliminated adsorbing gold onto the hydrogels and desorbing into 3 M HCl solution containing 0.8 M thiourea. These hydrogels were found to be highly open pore size. This property of the hydrogels make them attractive due to high adsorption capacity of gold ions on/in the hydrogels penetrating inside and react to all functional groups in the interior surface of the hydrogels.     

Concentration-Dependent Seeding as a Strategy for Fabrication of Densely Packed Surface-Mounted Metal–Organic Frameworks (SURMOF) Layers

The layer-by-layer (LbL) method is a well-established method for the growth of surface-attached metal–organic frameworks (SURMOFs). Various experimental parameters, such as surface functionalization or temperature, have been identified as essential in the past. In this study, inspired by these recent insights regarding the LbL SURMOF growth mechanism, the impact of reactant solutions concentration on LbL growth of the Cu₂(F₄bdc)₂(dabco) SURMOF (F₄bdc²⁻=tetrafluorobenzene-1,4-dicarboxylate and dabco=1,4-diazabicyclo-[2.2.2]octane) in situ by using quartz-crystal microbalance and ex situ with a combination of spectroscopic, diffraction and microscopy techniques was investigated. It was found that number, size, and morphology of MOF crystallites are strongly influenced by the reagent concentration. By adjusting the interplay of nucleation and growth, we were able to produce densely packed, yet thin films, which are highly desired for a variety of SURMOF applications.     

Electric Field-Controlled Synthesis and Characterisation of Single Metal–Organic-Framework (MOF) Nanoparticles

Achieving control over the size distribution of metal–organic-framework (MOF) nanoparticles is key to biomedical applications and seeding techniques. Electrochemical control over the nanoparticle synthesis of the MOF, HKUST-1, is achieved using a nanopipette injection method to locally mix Cu²⁺ salt precursor and benzene-1,3,5-tricarboxylate (BTC³⁻) ligand reagents, to form MOF nanocrystals, and collect and characterise them on a TEM grid. In situ analysis of the size and translocation frequency of HKUST-1 nanoparticles is demonstrated, using the nanopipette to detect resistive pulses as nanoparticles form. Complementary modelling of mass transport in the electric field, enables particle size to be estimated and explains the feasibility of particular reaction conditions, including inhibitory effects of excess BTC³⁻. These new methods should be applicable to a variety of MOFs, and scaling up synthesis possible via arrays of nanoscale reaction centres, for example using nanopore membranes.     

MOF-Mediated Fabrication of a Porous 3D Superstructure of Carbon Nanosheets Decorated with Ultrafine Cobalt Phosphide Nanoparticles for Efficient Electrocatalysis and Zinc–Air Batteries

Superstructures have attracted great interest owing to their potential applications. Herein, we report the first scalable preparation of a porous nickel-foam-templated superstructure of carbon nanosheets decorated with ultrafine cobalt phosphide nanoparticles. Uniform two-dimensional (2D) Co-metal organic framework (MOF) nanosheets (Co-MNS) grow on nickel foam, followed by a MOF-mediated tandem (carbonization/phosphidation) pyrolysis. The resulting superstructure has a porous 3D interconnected network with well-arranged 2D carbon nanosheets on it, in which ultrafine cobalt phosphide nanoparticles are tightly immobilized. A single piece of this superstructure can be directly used as a self-supported electrode for electrocatalysis without any binders. This “one-piece” porous superstructure with excellent mass transport and electron transport properties, and catalytically active cobalt phosphide nanoparticles with ultrasmall size (3–4 nm), shows excellent trifunctional electrocatalytic activities for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR), achieving great performances in water splitting and Zn–air batteries.     

Synthesis and Characterization Performance of Amphiphilic ZnO,a Novel Photocatalyst Suitable for Degradation of Contaminants in Oil–Water Two Phase System

Russian Journal of Physical Chemistry A - Amphiphilic zinc oxide (ZnO) was successfully prepared by modifing neat ZnO with silane coupling reagent KH-570. The modified ZnO and neat ZnO were...     

Direct C−H Trifluoromethylation of (Hetero)Arenes in Water Enabled by Organic Photoredox-Active Amphiphilic Nanoparticles

Photoredox-catalyzed chemical conversions are predominantly operated in organic media to ensure good compatibility between substrates and catalysts. Yet, when conducted in aqueous media, they are an attractive, mild, and green way to introduce functional groups into organic molecules. We here show that trifluoromethyl groups can be readily installed into a broad range of organic compounds by using water as the reaction medium and light as the energy source. To bypass solubility obstacles, we developed robust water-soluble polymeric nanoparticles that accommodate reagents and photocatalysts within their hydrophobic interior under high local concentrations. By taking advantage of the high excited state reduction potential of N-phenylphenothiazine (PTH) through UV light illumination, the direct C−H trifluoromethylation of a wide array of small organic molecules is achieved selectively with high substrate conversion. Key to our approach is slowing down the production of CF₃ radicals during the chemical process by reducing the catalyst loading as well as the light intensity, thereby improving effectiveness and selectivity of this aqueous photocatalytic method. Furthermore, the catalyst system shows excellent recyclability and can be fueled by sunlight. The method we propose here is versatile, widely applicable, energy efficient, and attractive for late-stage introduction of trifluoromethyl groups into biologically active molecules.     

Potentiometric Determination of the Stability Constants of Trimethyltin(IV) Chloride Complexes with Imino-bis(Methylphosphonic Acid) in Water and Dioxane–Water Mixtures

The interaction of trimethyltin(IV) (TMT) with imino-bis(methylphosphonic acid) (IDP), abbreviated as H₄L, was investigated at 25 °C and at ionic strength 0.1 mol⋅dm⁻³ (NaNO₃) using a potentiometric technique. The formation constants of the complexes formed in solution were calculated using the nonlinear least-squares program MINIQUAD-75. The stoichiometry and stability constants are reported for the complexes formed. The results show the formation of 110, 111, 112 and 11-1 complexes for the TMT–IDP system. The concentration distribution of the various complex species was evaluated. The effect of dioxane as a solvent, on both the protonation constants and the formation constants of trimethyltin(IV) complexes with IDP, is discussed. The thermodynamic parameters ΔH ^∘ and ΔS ^∘ calculated from the temperature dependence of the equilibrium constants were evaluated. The effect of ionic strength on the protonation constants of IDP is also discussed.     

The Effect of Concentration Parameters on Complexation in the Iron(0)–Iron(II)–Glycine–Water System

The processes of formation of iron(II) complexes in aqueous glycine solutions in the pH range of 1.0–8.0 at 298 K and ionic strength of 1 mol/L (NaClO₄) are studied using Clark and Nikolskii’s oxidation potential method. The type and number of coordinated ligands, the nuclearity, and the total composition of the resulting complexes are determined. The following complex species are formed in the investigated system: [Fe(OH)(H₂O)₅]⁺, [FeHL(H₂O)₅]²⁺, [Fe(HL)(OH)(H₂O)₄]⁺, [Fe(OH)₂(H₂O)₄]⁰, [Fe₂(HL)₂(OH)₂(H₂O)₈]²⁺, and [Fe(HL)₂(H₂O)₄]²⁺. Their formation constants are calculated by the successive iterations method using Yusupov’s theoretical and experimental oxidation function. The model parameters of the resulting coordination compounds are determined.     

Fabrication and interfacial morphologies of methanol–melamine–formaldehyde (MMF) shell microPCMs/epoxy composites

Microcapsules containing phase change materials (microPCMs) have many potential applications because of their thermoregulation or thermosaving abilities. At the same time, it is still essential to understand the interface stability of microPCMs/polymer composites during a thermal transmission. The aim of this work was to fabricate novel microPCMs containing dodecanol by an in situ polymerization using methanol-modified melamine–formaldehyde (MMF) prepolymer as shell material and investigate the interface morphologies of microPCMs/epoxy composites treated by a simulant thermal process with a ten times repeated temperature variation. A series of microPCMs were fabricated by 1,000–3,000 r·min⁻¹ emulsion speed with the PCM contents of 40–70%. The average diameter, melting temperature, and encapsulation efficiency of microPCMs were 1–16 μm, 19.5 °C, and 97.4%, respectively. Tests results indicated that the properties of the microPCMs were greatly affected by core/shell ratios and emulsification stirring rates of preparation conditions. With the increasing of stirring rates, the average diameters of microPCMs were sharply decreased. The encapsulation efficiency (E _e) values of microPCMs increased with the increasing of stirring rates. The contents of PCM in microcapsules (C _t) and the average diameter of microPCMs both affected the interface morphologies of microPCMs/epoxy composites after the repeated thermal treatments. Microcracks and gaps occurred after a thermal treatment in the interface of microPCMs and epoxy matrix obviously. The internal stress generated by the expansion or shrinking of the microPCMs was the main factor leading to the interface morphology changes and damaged of composites.     

Interfacial and Thermodynamic Properties of Formation of Water‐in‐Oil Microemulsions with Surfactants (SDS and CTAB) and Cosurfactants (n‐Alkanols C5–C9)

The interfacial and thermodynamic properties of water‐in‐oil microemulsion systems consisting of water, isopropyl myristate, n‐alkanol, and surfactant have been investigated using the method of dilution. The surfactants used were hexadecyl trimethylammonium bromide and sodium dodecylsulfate, and the cosurfactants were n‐alkanols with varying chain length from (C₅–C₉). The distribution of cosurfactant (n‐alkanol) between the interface of water and oil regions at the threshold level of stability as well as the energetics of the transfer of the cosurfactant from the oil to the interfacial region have been examined as a function of varying cosurfactant chain length (C₄–C₉) and temperature. The structural parameters (including dimension, population density and effective water pool radius) of the dispersed water droplets in the oil phase have also been evaluated and correlated with alkanol chain length.     

Stability Constants of Copper(II) Glycylglycinate Complexes in Water–Dimethylsulfoxide Solutions

Russian Journal of Physical Chemistry A - Stability constants of normal and copper(II) bis-glycylglycinate complexes in water–dimethylsulfoxide solutions of variable composition are...