Efficient, fast, simple, and eco-friendly methods for separation of toxic chromium(VI) ions based on ion exchangers and polymer materials impregnated with Cyphos IL 101, Cyphos IL 104, or D2EHPA.

In this study, we present the results of the first comparison of the elimination of toxic Cr(VI) ions, which are hazardous contamination of the environment, from aqueous solutions using ion exchangers (IEs) and polymer materials (PMs) impregnated with D2EHPA or ionic liquids (Cyphos IL 101 and Cyphos IL 104). Sorption of Cr(VI) ions and desorption from the formulated sorption materials were carried out. In comparison, classical solvent extraction was accomplished. Fourier transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and atomic force microscopy (AFM) have been used for characterization of the structure of developed IEs and PMs. The highest efficiency of adsorption of Cr(VI) ions was obtained using PMs with ionic liquids (>82%). Desorption from these materials were also very efficient (>75%). On the contrary, the application of IEs allowed for obtaining the best results of both, sorption and desorption processes when using D2EHPA (75% and 72%, respectively). The application of PMs and IEs is part of the green chemistry, and the conducted elimination of chromium(VI) ions using developed materials allows for the conclusion that they can potentially be used on a larger scale, e.g., for the treatment of industrial wastewater rich in Cr(VI) ions.

The Latest Achievements of Liquid Membranes for Rare Earth Elements Recovery from Aqueous Solutions-A Mini Review.

The systematic increase in the use of rare earth elements (REEs) in various technologically advanced products around the world (e.g., in electronic devices), the growing amount of waste generated by the use of high-tech materials, and the limited resources of naturally occurring REE ores resulted in an intensive search for effective and environmentally safe methods for recovering these elements. Among these methods, techniques based on the application of various types of liquid membranes (LMs) play an important role, primarily due to their high efficiency, the simplicity of membrane formation and use, the utilization of only small amounts of environmentally hazardous reagents, and the possibility of simultaneous extraction and back-extraction and reusing the membranes after regeneration. However, because both primary and secondary sources (e.g., waste) of REEs are usually complex and contain a wide variety of components, and the selectivity and efficiency of LMs depend on many factors (e.g., the composition and form of the membrane, nature of the recovered ions, composition of the feed and stripping phases, etc.), new membranes are being developed that are "tailored" to the properties of the recovered rare earth elements and to the character of the solution in which they occur. This review describes the latest achievements (since 2019) related to the recovery of a range of REEs with the use of various liquid membranes (supported liquid membranes (SLMs), emulsion liquid membranes (ELMs), and polymer inclusion membranes (PIMs)), with particular emphasis on methods that fall within the trend of eco-friendly solutions.

The Application of Polymer Inclusion Membranes for the Removal of Emerging Contaminants and Synthetic Dyes from Aqueous Solutions-A Mini Review.

Pollution of the environment, including water resources, is currently one of the greatest challenges due to emerging new contaminants of anthropogenic origin. Of particular concern are emerging organic pollutants such as pharmaceuticals, endocrine disruptors, and pesticides, but also other industrial pollutants, for example, synthetic dyes. The growing demand for environmentally friendly and economical methods of removing emerging contaminants and synthetic dyes from wastewater resulted in increased interest in the possibility of using techniques based on the application of polymer inclusion membranes (PIMs) for this purpose. PIM-based techniques are promising methods for eliminating emerging contaminants and synthetic dyes from aqueous solutions, including wastewater, due to high efficiency, membranes versatility, ease/low cost of preparation, and high selectivity. This review describes the latest developments related to the removal of various emerging contaminants and synthetic dyes from aqueous solutions using PIMs over the past few years, with particular emphasis on research aimed at increasing the effectiveness and selectivity of PIMs, which may contribute to wider use of these methods in the future.

The Use of Polymer Inclusion Membranes for the Removal of Metal Ions from Aqueous Solutions-The Latest Achievements and Potential Industrial Applications: A Review.

The growing demand for environmentally friendly and economical methods of removing toxic metal ions from polluted waters and for the recovery of valuable noble metal ions from various types of waste, which are often treated as their secondary source, has resulted in increased interest in techniques based on the utilization of polymer inclusion membranes (PIMs). PIMs are characterized by many advantages (e.g., the possibility of simultaneous extraction and back extraction, excellent stability and high reusability), and can be adapted to the properties of the removed target analyte by appropriate selection of carriers, polymers and plasticizers used for their formulation. However, the selectivity and efficiency of the membrane process depends on many factors (e.g., membrane composition, nature of removed metal ions, composition of aqueous feed solution, etc.), and new membranes are systematically designed to improve these parameters. Numerous studies aimed at improving PIM technology may contribute to the wider use of these methods in the future on an industrial scale, e.g., in wastewater treatment. This review describes the latest achievements related to the removal of various metal ions by PIMs over the past 3 years, with particular emphasis on solutions with potential industrial application.

Efficient Recovery of Noble Metal Ions (Pd2+, Ag+, Pt2+, and Au3+) from Aqueous Solutions Using N,N'-Bis(salicylidene)ethylenediamine (Salen) as an Extractant (Classic Solvent Extraction) and Carrier (Polymer Membranes).

This paper presents the results of the first application of N,N'-bis(salicylidene)ethylenediamine (salen) as an extractant in classical liquid-liquid extraction and as a carrier in membrane processes designed for the recovery of noble metal ions (Pd2+, Ag+, Pt2+, and Au3+) from aqueous solutions. In the case of the utilization of membranes, both sorption and desorption were investigated. Salen has not been used so far in the sorption processes of precious metal ions. Recovery experiments were performed on single-component solutions (containing only one type of metal ions) and polymetallic solutions (containing ions of all four metals). The stability constants of the obtained complexes were determined spectrophotometrically. In contrast, electrospray ionization high-resolution mass spectrometry (ESI-HRMS) was applied to examine the elemental composition and charge of the generated complexes of chosen noble metal ions and salen molecules. The results show the great potential of N,N'-bis(salicylidene)ethylenediamine as both an extractant and a carrier. In the case of single-component solutions, the extraction percentage was over 99% for all noble metal ions (molar ratio M:L of 1:1), and in the case of a polymetallic solution, it was the lowest, but over 94% for platinum ions and the highest value (over 99%) for gold ions. The percentages of sorption (%Rs) of metal ions from single-component solutions using polymer membranes containing N,N'-bis(salicylidene)ethylenediamine as a carrier were highest after 24 h of the process (93.23% for silver(I) ions, 74.99% for gold(III) ions, 69.11% and 66.13% for palladium(II) and platinum(II) ions, respectively), similar to the values obtained for the membrane process conducted in multi-metal solutions (92.96%, 84.26%, 80.94%, and 48.36% for Pd(II), Au(III), Ag(I), and Pt(II) ions, respectively). The percentage of desorption (%Rdes) was very high for single-component solutions (the highest, i.e., 99%, for palladium solution and the lowest, i.e., 88%, for silver solution), while for polymetallic solutions, these values were slightly lower (for Pt(II), it was the lowest at 63.25%).

The Application of 2,6-Bis(4-Methoxybenzoyl)-Diaminopyridine in Solvent Extraction and Polymer Membrane Separation for the Recovery of Au(III), Ag(I), Pd(II) and Pt(II) Ions from Aqueous Solutions.

The work describes the results of the first application of 2,6-bis(4-methoxybenzoyl)-diaminopyridine (L) for the recovery of noble metal ions (Au(III), Ag(I), Pd(II), Pt(II)) from aqueous solutions using two different separation processes: dynamic (classic solvent extraction) and static (polymer membranes). The stability constants of the complexes formed by the L with noble metal ions were determined using the spectrophotometry method. The results of the performed experiments clearly show that 2,6-bis(4-methoxybenzoyl)-diaminopyridine is an excellent extractant, as the recovery was over 99% for all studied noble metal ions. The efficiency of 2,6-bis(4-methoxybenzoyl)-diaminopyridine as a carrier in polymer membranes after 24 h of sorption was lower; the percentage of metal ions removal from the solutions (%Rs) decreased in following order: Ag(I) (94.89%) > Au(III) (63.46%) > Pt(II) (38.99%) > Pd(II) (23.82%). The results of the desorption processes carried out showed that the highest percentage of recovery was observed for gold and silver ions (over 96%) after 48 h. The results presented in this study indicate the potential practical applicability of 2,6-bis(4-methoxybenzoyl)-diaminopyridine in the solvent extraction and polymer membrane separation of noble metal ions from aqueous solutions (e.g., obtained as a result of WEEE leaching or industrial wastewater).

Tautomeric equilibrium, proton affinity and mass spectrometry fragmentation of flexible hydrogen-bonded precursors and rigid [Formula: see text] fluorescent dyes.

The stability of two groups of conformationally locked molecules, similar in topology, but differing only by the type of the bridge rigidifying their structure, is studied. The series of the less-rigid 2-phenacylheterocyclic compounds and their stiff difluoroboranyl derivatives are investigated for the determination of the effect of [Formula: see text]/S/O replacement in a five-membered heterocyclic ring and the presence of a strong electron-donating group on the tautomeric equilibrium, protonation affinity, and fragmentation pattern observed in the structural elucidation by means of mass spectrometry technique. The results of the [Formula: see text]B97X-D/6-311++G(d,p) calculations, the topological analysis of electron density as well as the experimental MS measurements show the importance of the number of heteroatoms, their properties, and location in the molecule for the rational design of the systems of desired stable tautomers or the favorable protonation sites. The obtained data allow for the understanding of the fundamentals of the novel highly fluorescent difluoroborates fragmentation behavior, vital for their structural elucidation with the application of high-resolution tandem mass spectrometry methods.

Simultaneous Recovery of Precious and Heavy Metal Ions from Waste Electrical and Electronic Equipment (WEEE) Using Polymer Films Containing Cyphos IL 101.

In this article, the application of a polymer film containing the ionic liquid Cyphos IL 101 for the simultaneous recovery of precious and heavy metal ions ((Ni(II), Zn(II), Co(II), Cu(II), Sn(II), Pb(II), Ag(I), Pd(II), and Au(III)) from waste electrical and electronic equipment (WEEE) is described. The experiments were performed for solutions containing metal ions released from computer e-waste due to leaching carried out with concentrated nitric(V) acid and aqua regia. It was found that the applied polymer film allows for the efficient recovery of precious metals (98.9% of gold, 79.3% of silver, and 63.6% of palladium). The recovery of non-ferrous metals (Co, Ni, Cu, Zn, Sn, and Pb) was less efficient (25-40%). Moreover, the results of the performed sorption/desorption processes show that the polymer film with Cyphos IL 101 can be successfully used after regeneration to recover metals ions several times.

N,N'-Bis(salicylidene)ethylenediamine (Salen) as an Active Compound for the Recovery of Ni(II), Cu(II), and Zn(II) Ions from Aqueous Solutions.

In this paper, three main methods of metal ion separation, i.e., liquid-liquid extraction, transport across polymer inclusion membranes (PIMs), and sorption/desorption, are described. In all of them, N,N'-bis(salicylidene)ethylenediamine (salen) was used as an active compound, i.e., as an extractant or as a carrier for the recovery of Ni(II), Cu(II), or Zn(II) ions from aqueous solutions. In each case, the recovery was performed on a model solution, which contained only a single metal ion. The obtained results were compared with the author's previous results for the separation of metal ions using ß-diketones, since both ß-diketones and salen form the so-called Werner-type complexes. Electrospray ionization high-resolution mass spectrometry (ESI-HRMS) was also applied to confirm the ability of the carrier to form complexes with metal ions in a solution. Moreover, spectrophotometry was used to determine the stability constant of the obtained complexes.

Electrospray ionization collision induced dissociation of thiocarbocyanine and selenocarbocyanine dyes.

The effect of the properties of sulphur and selenium atoms, the composition and location of substituents (-CH3 , -OCH3 , -C2 H5 , and -C3 H6 -((N+ Br- )C5 H5 )), and the charge state on the collision induced dissociation (CID) behaviour of ions generated by electrospray ionization (ESI) of thiocarbocyanine and selenocarbocyanine dyes have been investigated. The results show that, for of all the examined singly charged ions, the main dissociation channel was related to the formation of distonic ions, generated as a result of cleavages within the dimethine bridge. In the case of doubly charged ions (with propyl-pyridinium substituents), competition between fragmentation processes related to charges located at different nitrogen atoms has been observed. The S/Se replacement also has an impact on the CID behaviour of the examined carbocyanine dyes. On the basis of the performed CID MS/MS experiments, general rules for the CID of thiocarbocyanine and selenocarbocyanine dyes have been proposed.

Synthesis and Photophysical Properties of Novel Donor-Acceptor N-(Pyridin-2-yl)-Substituted Benzo(thio)amides and Their Difluoroboranyl Derivatives.

The unprecedented N-pyridin-2-yl substituted benzo(thio)amides were prepared and subsequently converted into the cyclic difluoroboranyl (BF2) derivatives. Mass spectrometry, multinuclear NMR, IR, and elemental analysis confirmed the structure of these compounds. UV/vis and fluorescence spectroscopy as well as first-principle calculations were used to study their properties. For the first time, the influence of both the O/S replacement and presence/absence of the BF2 moiety on the photophysical properties of compounds exhibiting charge transfer properties were examined experimentally and theoretically. We show that the sulfur-containing compound has a much smaller emission quantum yield than its oxygen counterpart. The fluorescence quantum yield is much higher upon formation of the difluoroboranyl complex.

Electron capture dissociation and collision induced dissociation of S-dipalmitoylated peptides.

Here we investigate the effect of S-dipalmitoylation on the electron capture dissociation (ECD) behavior of peptides. The ECD and collision induced dissociation (CID) of peptides modified by covalent attachment of [(RS)-2,3-di(palmitoyloxy)-propyl] (PAM2) group to cysteine residues [C(PAM2)LEYDTGFK and RPPGC(PAM2)SPFK] were examined. The results suggest that ECD of S-dipalmitoylated peptides can provide both primary sequence information and structural information regarding the modification. The structural information provided by CID is complementary to that provided by ECD.

Electron induced dissociation (EID) tandem mass spectrometry of octaethylporphyrin and its iron(III) complex.

EID tandem mass spectrometry of singly-charged electrosprayed ions of octaethylporphyrin (OEP) and its iron(III) complex results in ionisation to give doubly-charged precursor and fragment ions. Singly-charged fragments are also observed. EID fragmentation differs significantly to that observed in electron ionisation mass spectrometry.

Electron induced dissociation: a mass spectrometry technique for the structural analysis of trinuclear oxo-centred carboxylate-bridged iron complexes.

We report electron induced dissociation (EID) Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry of the singly-charged cations [Fe(3)O(CH(3)COO)(6)](+) and [Fe(3)O(HCOO)(6)+H(2)O](+). Trinuclear oxo-centered carboxylate-bridged iron complexes of this type are of interest due to their electronic and magnetic properties, and because of their role as synthetic precursors of single molecule magnets. EID of these complexes is particularly efficient and provides detailed information about the triangular core, and the nature and number of ligands. EID behavior is in marked contrast to the collision induced dissociation (CID) of these species. Whereas EID allows virtually complete structural characterization, the structural information provided by CID is very limited. The results suggest that EID is particularly suitable for the structural analysis of singly-charged polynuclear metal complexes.

Electron capture dissociation mass spectrometry of metallo-supramolecular complexes.

The electron capture dissociation (ECD) of metallo-supramolecular dinuclear triple-stranded helicate Fe(2)L(3)(4+) ions was determined by Fourier transform ion cyclotron resonance mass spectrometry. Initial electron capture by the di-iron(II) triple helicate ions produces dinuclear double-stranded complexes analogous to those seen in solution with the monocationic metal centers Cu(I) or Ag(I). The gas-phase fragmentation behavior [ECD, collision-induced dissociation (CID), and infrared multiphoton dissociation (IRMPD)] of the di-iron double-stranded complexes, (i.e., MS(3) of the ECD product) was compared with the ECD, CID, and IRMPD of the Cu(I) and Ag(I) complexes generated from solution. The results suggest that iron-bound dimers may be of the form Fe(I)(2)L(2)(2+) and that ECD by metallo-complexes allows access, in the gas phase, to oxidation states and coordination chemistry that cannot be accessed in solution.

Characterization of polyphosphoesters by Fourier transform ion cyclotron resonance mass spectrometry.

FT-ICR mass spectrometry, together with collision-induced dissociation and electron capture dissociation, has been used to characterize the polyphosphoester poly[1,4-bis(hydroxyethyl)terephthalate-alt-ethyloxyphosphate] and its degradation products. Three degradation pathways were elucidated: hydrolysis of the phosphate-[1,4-bis(hydroxyethyl)terephthalate] bonds; hydrolysis of the phosphate-ethoxy bonds; and hydrolysis of the ethyl-terephthalate bonds. The dominant degradation reactions were those that involved the phosphate groups. This work constitutes the first application of mass spectrometry to the characterization of polyphosphoesters and demonstrates the suitability of high mass accuracy FT-ICR mass spectrometry, with CID and ECD, for the structural analysis of polyphosphoesters and their degradation products.

Electron capture dissociation and collision-induced dissociation of metal ion (Ag(+), Cu(2+), Zn(2+), Fe(2+), and Fe(3+)) complexes of polyamidoamine (PAMAM) dendrimers.

The electron capture dissociation (ECD) and collision-induced dissociation (CID) of complexes of polyamidoamine (PAMAM) dendrimers with metal ions Ag(+), Cu(2+), Zn(2+), Fe(2+), and Fe(3+) were determined by Fourier transform ion cyclotron resonance mass spectrometry. Complexes were of the form [PD + M + mH](5+) where PD = generation two PAMAM dendrimer with amidoethanol surface groups, M = metal ion, m = 2-4. Complementary information regarding the site and coordination chemistry of the metal ions can be obtained from the two techniques. The results suggest that complexes of Fe(3+) and Cu(2+) are coordinated via both core tertiary amines, whereas coordination of Ag(+) involves a single core tertiary amine. The Zn(2+) and Fe(2+) complexes do not appear to involve coordination by the dendrimer core.

Electron capture dissociation, electron detachment dissociation, and collision-induced dissociation of polyamidoamine (PAMAM) dendrimer ions with amino, amidoethanol, and sodium carboxylate surface groups.

Here, we investigate the effect of the structure (generation) and nature of the surface groups of different polyamidoamine (PAMAM) dendrimers on electron-mediated dissociation, either electron capture dissociation (ECD) or electron detachment dissociation (EDD), and compare the fragmentation with that observed in collision-induced dissociation (CID). ECD and EDD of the PAMAM dendrimers resulted in simple mass spectra, which are straightforward to interpret, whereas CID produced complex mass spectra. The results show that electron-mediated dissociation (ECD and EDD) of PAMAM dendrimers does not depend on the nature of the surface group but tends to occur within the innermost generations. CID of the PAMAM dendrimers showed a strong dependence on the nature of the surface group and occurred mostly in the outer generation. The results demonstrate the potential utility of ECD and EDD as a tool for the structural analysis of PAMAM dendrimers.