Anions Cl Research Articles

High corrosion resistance duplex fcc + hcp cobalt based entropic alloys: An experimental and theoretical investigation

A series of duplex fcc + hcp Co-based entropic alloys are being discovered as a new category of entropic alloys with outstanding mechanical properties, especially to overcome a typical mechanical trade-off between strength and ductility. In this work, CALPHAD-based (CALculation of PHAse Diagram) thermodynamic calculations were performed to facilitate alloy design and to understand corrosion behaviors. The kinetics of the electrochemical corrosion for designed alloys in typical aggressive anion Cl- was investigated by electrochemical tests, including open circuit potential (OCP), polarization and cyclic polarization curves, and electrochemical impedance spectroscopy (EIS). The valence state and the surface morphologies of the passive films were investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). High corrosion resistance materials with high strength and ductility performances were discovered in the present work. Except for Ni-oxides, various spinel compounds and many other oxides including Co2O3, Cr2O3, Fe2O3, MnO, MoO3, CoCr2O4, FeCr2O4, CoFe2O4, and CoMoO4 were observed in the passive films. The adsorbed and penetrated corrosive anion Cl- will be prone to breakdown the passive films with less Cr2O3, CoCr2O4 and MoO3 to form pitting corrosion (also include other localized corrosion, such as intergranular corrosion and crevice corrosion). The microstructure of the hcp martensite with the fcc matrix has played an important role in the propagation of the localized anodic dissolution in the form of cleavage and quasi-cleavage. The theoretical calculations are in good agreement with the experimental observations. This paper paves a way for the future development of high-performance Co-based entropic alloys served in some harsh environments.

Insights into a newly discovered mechanism for 1O2 formation in a chlorine ion-mediated sulfate radical-advanced oxidation process system for levofloxacin degradation in an aqueous solution

The dual effect of chloride anions (Cl−) on sulfate radical-advanced oxidation process (SR-AOP) systems has recently garnered increasing attention, particularly the inhibitory effects of Cl− on the degradation of organic pollutants. However, few studies have characterized the promoting effect of Cl− on SR-AOPs. Our study investigated the effect of Cl− on the degradation of levofloxacin (LVF) in peroxymonosulfate (PMS) with ZIF-67/VTM (Z-VTM) as an activator. With the addition of Cl−, singlet oxygen (1O2) was the dominant driver of LVF degradation in the Cl−/Z-VTM/PMS system, which differed from the dominant role of HOCl (generated from Cl−) in the degradation of organic pollutants in previous studies. To the best of our knowledge, our study is the first to describe the conversion of HOCl to 1O2 in a Cl−/Z-VTM/PMS system. 1O2 was effectively generated in Cl− containing water at a 3.0–9.0 pH range. This work provides novel insights into the formation of ROS from HOCl during the degradation of organic pollutants in SR-AOPs, which is of great significance for the removal of organic pollutants in wastewater with high salt concentrations.

Molecular design of covalent−organic framework membranes for Li+/Mg2+ separation: Significant charge effect

In this study, molecular simulation is utilized to explore the charge effect in COF membranes on separation performance. Three types of COF membranes with different functional groups (Tp-Tta-COOH, Tp-Tta-COO− and Tp-Tta-NH3+) and thus different charges are designed. It is found that the positively charged membrane (Tp-Tta-NH3+) shows higher ion selectivity in mixed Li+/Mg2+ ion solution, compared with the negatively charged and neutral membranes. In Tp-Tta-NH3+ membrane, the effective pore size is reduced by the secondary confinement effect of Cl− ions. The orderly arranged anions (Cl−) reduce the actual pore size and generate the secondary confinement effect, which fortifies the pore-entrance sieving effect, and due to the large difference in hydration energies of Li+ and Mg2+ ions, the former is easier to dehydrate and enter the pore. The charge effect in Li+/Mg2+ separation uncovered by molecular simulation is microscopically insightful toward the design of COF membranes and other organic framework membranes for high-performance ion separation.

High performance carbon dioxide electroreduction in ionic liquids with in situ shell-isolated nanoparticle-enhanced Raman spectroscopy

Electrochemical CO2 reduction (ECR) has received significant attention with the rising emphasis on renewable energy. However, high Faradaic efficiency (FE) and large current density are still the challenge for ECR. Selecting ionic liquids (ILs) as electrolytes for ECR has advantages of enhancing the FE and improving the current density. Herein, in situ shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) is employed to study the ECR process on nickel foam (NF) in imidazolium ILs. Results show that the IL 1-Butyl-3-methylimidazolium chloride (BmimCl) presents the best performance towards ECR. The FE of CO is as high as 94.6 %, with a considerable current density of 72 mA cm−2. Particularly, the FE of CO can keep around 82 % after 15 h continuous electrolysis, indicating the good stability. Structural details of the BmimCl-NF electrode interface are obtained by in situ SHINERS along with density functional theory (DFT) calculations, indicating that the adsorption configuration change of imidazolium cations of BmimCl on NF electrode is favorable for ECR. Moreover, the strong interaction between Cl anions of BmimCl and CO2 could bend and activate the CO2 molecules. The reaction intermediate CO32– confirmed by in situ SHINERS helps to determine the reaction pathway. Particularly, the DFT calculations show the priority of the ECR reaction on Ni surface for CO product. This work presents a promising method for in situ studies of the CO2 electroreduction mechanism in ionic liquids.

Changes in Ion Concentrations upon the Binding of Short Polyelectrolytes on Phospholipid Bilayers: Computer Study Addressing Interesting Physiological Consequences.

This computer study was inspired by the experimental observation of Y. Qian et al. published in ACS Applied Materials and Interfaces, 2018 that the short positively charged β-peptide chains and their oligomeric analogues efficiently suppress severe medical problems caused by antimicrobial drug-resistant bacteria despite them not penetrating the bacterial membrane. Our coarse-grained molecular dynamics (dissipative particle dynamics) simulations confirm the tentative explanation of the authors of the experimental study that the potent antimicrobial activity is a result of the entropically driven release of divalent ions (mainly magnesium ions essential for the proper biological function of bacteria) into bulk solution upon the electrostatic binding of β-peptides to the bacterial membrane. The study shows that in solutions containing cations Na+, Ca2+ and Mg2+, and anions Cl−, the divalent cations preferentially concentrate close to the membrane and neutralize the negative charge. Upon the addition of positively charged oligomer chains (models of β-peptides and their analogues), the oligomers electrostatically bind to the membrane replacing divalent ions, which are released into bulk solvent. Our simulations indicate that the entropy of small ions (which controls the behavior of synthetic polyelectrolyte solutions) plays an important role in this and also in other similar biologically important systems.

The complexation of U(IV) ion with N, N, N′, N′-Tetraalkyl-Diglycolamide in aqueous solutions and extraction systems of varying anions

By comparing the absorption spectra of the two 1:3 species formed in 1 M HCl, 1 M HNO 3 and the reflectance spectrum of UL 3 ·4(ClO 4 ) (L = N, N, N′, N′-tetramethyl-diglycolamide) with the spectra of the extracted complexes of U(IV) with L′(L′ = N, N′-dimethyl-N, N′-dioctyl-diglycolamide), the participation of anions in the first coordination sphere is discovered in the extracted complexes of U(IV) with L′ for the first time in solvent extraction using tetraalkyldiglycoamides as extractants. • Three complex species of U(IV) with TMDGA are identified respectively in 1 M HNO 3 and 1 M HCl solution. • Single crystals of U(TMDGA) 3 ·4ClO 4 are grown and its structure is determined. • The participation of counter anions in the first coordination sphere of U(IV)in the extracted complexes with DMDODGA and in the complexes with TMDGA in HCl and HNO 3 media was confirmed. The complexation of U(IV) with N, N, N′, N′-tetramethyl-diglycolamide (TMDGA, L) has been investigated in 1 M HCl and 1 M HNO 3 solutions and in a solid compound UL 3 ·4(ClO 4 ) formed in aqueous solutions in parallel with that in the extraction system using N, N′-dimethyl-N, N′-dioctyl-diglycolamide (DMDODGA, L′) as extractant. Three species of U(IV):L complexes being 1:1, 1:2, and 1:3 (denoted as UL 4+ , UL 2 4+ and UL 3 4+ ) are identified spectroscopically in each of the two different aqueous media, 1 M HCl and 1 M HNO 3 . The different absorption spectra of the corresponding complexes indicate that the complexes formed in 1 M HCl and 1 M HNO 3 are not the same, suggesting that the anions Cl - and NO 3 – are involved in the complexes. By comparing the absorption spectra of the two 1:3 species formed in 1 M HCl, 1 M HNO 3 and the reflectance spectrum of UL 3 ·4(ClO 4 ) with the spectra of the extracted complexes of U(IV) with L′, the participation of anions in the first coordination sphere is discovered in the extracted complexes of U(IV) with L′ for the first time in solvent extraction using tetraalkyldiglycoamides as extractants.

Thermodynamic control on chemical weathering of river bedrock at the Aba and Qamdo in Kaschin-beck disease region, eastern Tibet Plateau

Groundwater is the main source of water for living and agriculture in an area. To investigate the relationship between water environment and Kaschin-beck disease (KBD), we collected published data on water samples (data from the KBD areas of Aba Prefecture, Qamdo area, the Yellow River Basin region and the non-KBD area of the Yangtze River Basin region) for thermodynamic simulations to further analyze the hydrogeochemical properties. The analysis results show that: (1) The groundwater in Aba Prefecture and Qamdo area is weakly alkaline. (2) The groundwater type in Aba Prefecture and Qamdo area is Ca-HCO3− type. (3) The average concentration of cations Mg2+and Ca2+ can be expressed as Yellow River Basin > Yangtze River Basin > Aba Prefecture > Qamdo area. The average concentration of cation Na+and anion Cl− can be expressed as Yellow River Basin > Qamdo area > Yangtze River Basin>Aba Prefecture. The value of TDS can be expressed as Yellow River Basin > Qamdo area > Yangtze River Basin > Aba Prefecture. This may indicate that there is no direct relationship between KBD and water environment. (4) The dissolution of calcite and dolomite in quartzite controls the change of element content of water. (5) Analysis of the Gibbs distribution shows that most of the elements in the groundwater of the KBD areas (Aba Prefecture, Qamdo area and the Yelllow River Basin region) and non-KBD area (the Yangtze River Basin region) majorly come from rock weathering. (6) The overall quality of groundwater is good, the salinity is low, and it is suitable for agricultural irrigation.

The crosstalk effect between ferrous and other ions metabolism in ferroptosis for therapy of cancer.

Ferroptosis is an iron-dependent cell death process characterized by excessive accumulation of reactive oxygen species and lipid peroxidation. The elucidation of ferroptosis pathways may lead to novel cancer therapies. Current evidence suggests that the mechanism of ferroptosis can be summarized as oxidative stress and antioxidant defense mechanisms. During this process, ferrous ions play a crucial role in cellular oxidation, plasma membrane damage, reactive oxygen species removal imbalance and lipid peroxidation. Although, disregulation of intracellular cations (Fe2+, Ca2+, Zn2+, etc.) and anions (Cl-, etc.) have been widely reported to be involved in ferroptosis, their specific regulatory mechanisms have not been established. To further understand the crosstalk effect between ferrous and other ions in ferroptosis, we reviewed the ferroptosis process from the perspective of ions metabolism. In addition, the role of ferrous and other ions in tumor therapy is briefly summarized.

The Influence of Anion-Stripped MIL-101(Cr) Dispersed in Thin-Film Polyvinyl Alcohol Membrane Matrix on the Methylene Blue Dye Separation

This study investigates the production and performance of a novel nanofiltration membrane for removal of cationic dye (Methylene blue) and multivalent cations. These positively charged membranes are made by dispersing a modified cationic metal–organic framework, Cl-MIL-101(Cr), into the polyvinyl alcohol matrix as a membrane skin layer. To this end, the mobile anion (Cl−) embedded in the MIL-101(Cr) structure plays a role to create a positive partial charge on the membrane. In this study, the effects of MOF content and their types on the membrane structure were considered by FTIR, XRD, FESEM, Zeta potential and water contact angle. The results have shown that membranes filled with Cl-MIL-101(Cr) attained higher permeate flux and rejection than those of MIL-101(Cr). Particularly, this study indicates that the low irreversible resistance (19.49%) and high flux return ratio (80.50%) have been related to the membrane containing 15% cationic Cl-MIL-101(Cr). However, this membrane rejected more than 30.41% of AlCl3 salt and 99.08% of methylene blue with approximate permeate flux of 20 L/m2·h. It is recommended that the fabricated membrane be placed in the flow path process of cationic dyes purification.

Removal of ofloxacin from wastewater by chloride electrolyte electro-oxidation: Analysis of the role of active chlorine and operating costs

Electro-oxidation (EO) has received increasing attention as an efficient and green method for removing pollutants from wastewater. Chloride anions (Cl−), which commonly exist in wastewater, can act as an electrolyte for the EO process. However, the role of reactive chlorine species (RCS) generated near electrodes is often underestimated. In this study, we generated hydroxyl radicals (OH) and RCS in a boron-doped diamond (BDD) electrode system and investigated its degradation mechanism for ofloxacin (OFX) removal. The findings suggested that OFX degradation was dominated by OH existing near the anode in solution, with RCS playing a supporting role. Based on the produced intermediates, we proposed an OFX decomposition pathway. The biological toxicities of the intermediates were evaluated through the ECOSAR and T.E.S.T. procedure. Nearly half of the intermediates are less toxic than the parent compound. After optimizing the operating parameters by the response surface methodology, 20 mg/L OFX was almost completely degraded after 10 min of reaction in 1.45 g/L NaCl with a current density (j) of 18 mA/cm2, and the total organic carbon was decreased by 30.55 %. The energy consumption and current efficiency were 0.648 kW·h/gTOC and 8.65 %, respectively. Comparing the operating costs of the proposed and other EO methods, our method emerged as a viable new treatment scheme for similar polluted wastewaters. This study aims to comprehensively understand the potential application value of BDD electrodes in the treatment of Cl− containing organic wastewater.

Regulating the distribution of acid sites in ZSM-11 zeolite with different halogen anions to enhance its catalytic performance in the conversion of methanol to olefins

Purposive regulation of the spatial location and distribution of acid sites in a zeolite catalyst, though still rather challenging, has proved to be an effective measure to enhance its performance in the conversion of methanol to olefins (MTO). Herein, a series of ZSM-11 zeolites were synthesized using different sodium halides (with tetrabutylammonium hydroxide (TBAOH) as the structure-directing agent); the effect of halogen anions (Cl-, Br- and I-) in the synthesis gel on the Al siting and thereon the spatial location and distribution of acid sites in the ZSM-11 zeolites as well as their relation to the catalytic performance in MTO was elaborately investigated. The results indicate that for the synthesis of high Si/Al ratio ZSM-11 zeolites (Si/Al > 60), the Cl- anions present in the synthesis gel can induce more Al atoms siting on the external surface of ZSM-11 crystals, thereby leading to a short catalytic lifetime in MTO due to the rapid coke deposition. In contrast, larger Br- or I- anions in the synthesis gel, owing to their stronger covalent interaction with the TBA+ cations, may moderate the formation of crystal silicate nuclei and lead to a uniform distribution of Al species in the inner straight channels, which can effectively suppress the surface coke deposition and inhibit the aromatic-based cycle for MTO. As a result, the high Si/Al ratio ZSM-11 zeolites obtained with Br- or I- in the synthesis gel exhibit much better catalytic stability in MTO and higher selectivity to propene and butene, in comparison with the ZSM-11 counterpart synthesized using Cl-. These results help to clarify the relation between the catalytic performance of ZSM-11 in MTO and the location of acid sites and thus bring forward a facile strategy to enhance the catalytic performance of zeolites through purposively regulating the spatial distribution of acid sites.

A New Paradigm in Pincer Iridium Chemistry: PCN Complexes for (De)Hydrogenation Catalysis and Beyond.

The discovery and development of organometallic catalysts is of paramount importance in modern organic synthesis, among which the ligand scaffolds play a crucial role in controlling the activity and selectivity. Over the past several decades, d8 transition-metal complexes of pincer ligands have been developed extensively thanks to their easy structural modification, versatile reactivities, and high stability. One paradigm is the bis(phosphine)-based pincer iridium complexes PCP-Ir, which are highly active for alkane dehydrogenation, partly due to their high thermostability. However, except for alkane dehydrogenation and related transformations, few applications of pincer iridium catalysis have been seen in organic synthesis. This mainly arises from the low functional-group compatibility and poor substrate scope and the limited catalytic chemistry that invariably involves Ir(I/III) redox processes initiated by oxidative addition of substrates to 14-electron (PCP)Ir fragments (the proposed catalytically active intermediates). In this Account, we describe our endeavor on the development of a new family of PCN-Ir complexes with initial intention on creating more efficient alkane dehydrogenation catalysts. The replacement of a soft, σ-donor phosphine arm in the PCP ligands by a harder, π-acceptor N-heteroarene (pyridine or oxazoline) not only provides an additional platform to modify the structural properties but also offers new modes of bond activation and novel reactivities and catalysis. One uniqueness of the PCN-Ir system lies in the formation, via ortho-C(sp2)-H cyclometalation of the pyridine unit in the PCNPy ligand, of the neutral monohydride (PCC)IrIIIHL (L = neutral ligand), which catalyzes positional and stereoselective 1-alkene-to-(E)-2-alkene isomerization. Moreover, the PCN-Ir catalysts effect ethanol dehydrogenation without decarbonylation, allowing for transfer hydrogenation of unactivated alkenes and trans-selective semihydrogenation of internal alkynes with user-friendly ethanol as the H-donor. Another feature originates from the ability of the pentacoordinate hydrido chloride complex (PCN)IrIIIHCl to undergo reversible solvent-coordination-induced-ionization (SCII), furnishing a cationic monohydride [(PCN)IrIIIH(Sol)]+Cl- bearing an uncoordinated Cl anion that effects selective hydrometalation of internal alkynes over the corresponding (Z)-alkenes; the resulting (PCN)IrIII(vinyl)Cl complex undergoes amine-assisted formal alcoholysis involving the protonation of the Cl anion by the activated IrIII-bound EtOH, again via the SCII pathway. Together these elementary reactions lay the foundation for cis-selective semihydrogenation of alkynes with EtOH. Further, the design of the oxazoline-containing chiral complexes (PCNOxa)IrIIIHCl enables asymmetric transfer hydrogenation of alkenes/ketones with ethanol. The efficient catalytic α-alkylation of unactivated esters/amides with alcohols is another case showing the benefit that the PCN-Ir catalyst can offer. These examples illustrate the profound impact of the pincer ligands on the reactivities and catalysis. We hope this Account will provide an in-depth view into the fundamentals of pincer iridium chemistry and ultimately broaden its applications in organic synthesis.

Construction of Efficient and Stable FAPbI3 Perovskite Solar Cells through Bifunctional Ionic Liquid‐Assisted Crystallization and Defect Passivation

FAPbI3 is considered one of the most ideal perovskite materials to construct highly efficient perovskite solar cell (PSC), but the poor phase stability and film‐forming properties hinder further performance improvements. Herein, an ionic liquid 3‐(2‐amino‐2‐oxoethyl)‐1‐methyl‐1H‐imidazol‐3‐ium chloride (AOMCl) with multifunctional cations and Cl anion to assist crystallization, reduce defects, and stabilize α‐FAPbI3 is reported. Results show that the perovskite film's nonradiative recombination and phase transition are suppressed after AOMCl treatment. The PSCs with AOMCl treatment obtain a power conversion efficiency (PCE) up to 22.01% with negligible hysteresis. In addition, the large‐area (1 cm2) device achieves a PCE of 17.11%. The AOMCl‐treated unencapsulated device exhibits impressive stability, maintaining an initial efficiency of over 94% after 1600 h in air environment. This work provides a strategy for designing FAPbI3 additive ideally.

Enhanced removal of tetracycline via advanced oxidation of sodium persulfate and biochar adsorption.

Advanced oxidation of antibiotic tetracycline (TC) is becoming an accessible and efficient technology. The removal of TC from the complex wastewater needs to be lucubrated. In this study, a TC removal system involving degradation and adsorption was established. TC degradation was accomplished by enhanced advanced oxidation via the addition of sodium persulfate (SP) and biochar into simulated wastewater containing Mn2+ and TC wastewater. The adsorption of TC and its derivatives was removed by biochar. The results indicate that the optimized reaction parameters were 3.0g/L of biochar prepared at 600°C (B600) and 400mg/L of SP under acidic condition, and the removal percentage of TC was 87.48%, including 74.23% of degradation and 13.28% of adsorption; the anions Cl-, NO3-, and H2PO4- had negligible effects on the removal of TC in this Mn2+/B600/SP system. The system also functioned well with an aqueous solution with a high chemical oxygen demand (COD) concentration. Electron paramagnetic resonance (EPR) analysis indicated that ·OH and SO4- free radicals were present in the Mn2+/B600/SP system. Based on the testing and analysis results, a removal mechanism and potential TC degradation pathway for this system were proposed. TC can be degraded by ·OH and SO4- via three degradation pathways. Mn2+ can be precipitated as MnO2, and a part of the TC and its derivatives can be adsorbed on the biochar surface. The Mn2+/B600/SP system also performed satisfactorily for a complex aqueous solution with various cations and antibiotics.

Neutrophil Myeloperoxidase-Mediated N-Demethylation of Quetiapine Leads to N-Desalkylquetiapine, a Pharmacologically Active Cytochrome P450 Metabolite

The atypical antipsychotic drugs, quetiapine and clozapine, are associated with idiosyncratic drug reactions (such as agranulocytosis or neutropenia) that are thought to involve reactive metabolites. Neutrophil myeloperoxidase (MPO) metabolism of quetiapine is not well-studied, but is metabolized by cytochrome P450. Based on structural similarity to clozapine, we hypothesized that quetiapine can be metabolized by MPO and that there is overlap between cytochrome P450 and MPO metabolism of quetiapine. The interaction of quetiapine and clozapine with MPO and MPO chlorination activity was studied using UV-vis spectrophotometry. The metabolites were characterized using liquid chromatography-mass spectrometry (LC-MS), and electron paramagnetic resonance (EPR) spectroscopy was used for detecting drug-catalyzed glutathione oxidation. In the presence of quetiapine, MPO compound II accumulated for about 7.5 min, whereas in the presence of clozapine, MPO compound II was not observed as it was rapidly reduced back to the resting state. Increasing quetiapine concentrations resulted in a decrease in MPO chlorination activity, while the opposite result was found in the case of clozapine. UV-vis spectral studies showed no change when quetiapine was oxidized in the absence and presence of chloride anion (Cl-, to catalyze chlorination reactions). Significant changes, however, were observed in the same assay with clozapine, where Cl- appeared to hinder the rate of clozapine metabolism. The MPO-catalyzed hydroxylated and dealkylated metabolites of quetiapine and hydroxylated metabolites of clozapine were observed from the LC-MS analyses, particularly when Cl- was included in the reaction. In addition, hydroxylated, dealkylated, and a proposed sulfoxide metabolite of quetiapine were also observed in the reaction catalyzed by human microsomes/NADPH. Lastly, compared to quetiapine, clozapine metabolism by MPO/H2O2 and glutathione produced more glutathionyl radicals using EPR spin trapping. In conclusion, MPO/H2O2/Cl- was shown to metabolize quetiapine to S-oxidation and P450-like dealkylation products, and quetiapine metabolites were generally less reactive than clozapine.

Interactions of basic compounds with ionic liquids used as oils in microemulsion liquid chromatography

Aqueous microemulsions (MEs), where an oil coexists with water in the presence of the anionic surfactant sodium dodecyl sulphate (SDS), have been proposed as a solution to decrease the amount of organic solvent in the mobile phase needed in reversed-phase liquid chromatography (RPLC). However, the oil phase of a typical ME is volatile, toxic and flammable, and although it is added in a small amount, it would be desirable to avoid it from an environmental perspective. This is the reason for the proposal of Peng et al. (J. Chromatogr. A 1499 (2017) 132‒139) to replace the oil in microemulsion liquid chromatography (MELC) by the apolar ionic liquid (IL) 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6C1IM][PF6]), to analyse neutral phenolic acids at acidic pH. Based on this report, an MELC procedure is here proposed for β-adrenoceptor antagonists, which are basic compounds where the dominant species is cationic. To verify the formation of MEs containing SDS and IL, and elucidate the interactions between the cationic basic compounds with the SDS anion, and the cation and anion in the IL, an extensive study was carried out with several methylimidazolium ILs containing the cations [C2C1IM]+, [C4C1IM]+, or [C6C1IM]+, combined with the anions Cl–, BF4–, or PF6–, using 1-butanol as co-surfactant. The behaviour was compared with that observed in classical MELC with octane, micellar liquid chromatography with SDS and 1-propanol, and RPLC with mobile phases containing an IL and acetonitrile.

Nanoscale Zero-Valent Iron Confined in Anion Exchange Resins to Enhance Selective Adsorption of Phosphate from Wastewater

The removal and recovery of phosphorus from wastewater are crucial for reducing eutrophication and alleviating phosphate rock depletion. In this study, nanoscale zero-valent iron (nZVI) confined in Alfa Aesar Amberlite IRA-402 (Cl) anion exchange resin composite adsorbents was developed by in situ reduction and deposition (denoted as nZVI-402-Cl) to remove phosphate from simulated and real wastewater. Surface and structure characterizations revealed that nZVI particles with a partially oxidized surface were loaded on the surface and inside the anion exchange resin. The phosphate adsorption capacity of nZVI-402-Cl was found to be high over a wide pH range (3.0–11.0), with a maximum adsorption capacity of 56.27 mg P/g at pH 7.2. Despite the presence of interfering sulfate and nitrate anions, nZVI-402-Cl maintained its high phosphate adsorption capacity owing to its excellent selectivity. The confinement of nZVI in anion exchange resins, in particular, could reduce the negative effects of humic acid on phosphate removal. After five regeneration/use cycles, the phosphate removal of nZVI-402-Cl was maintained close to 95%. In column mode tests, the nZVI-402-Cl column process generates ∼1850 bed volume (BV) clean water ([phosphorus] < 0.1 mg/L) from the wastewater treatment plant effluents. In contrast, the value of the IRA-402 column is only ∼900 BV. nZVI-402-Cl has proven to be an efficient and selective adsorbent for practical phosphate removal and recovery in different water environments.

A Facile Colorimetric Method for Ultra-rapid and Sensitive Detection of Copper Ions in Water

It is of great meaning to develop a facile, reliable and sensitive method to detect copper ions in water. In the study, a facile method has been developed for rapid and sensitive detection of Cu2+. An interesting phenomenon has been observed that 3,3′,5,5′-tetramethylbenzidine (TMB) ethanol solution can be extremely fast passed from colorless to yellow once Cu2+ ions are added. It easily occurs to us that Cu2+ can be quantitatively determined via the absorbance at 904 nm of the color changed TMB solution. More importantly, some specific anions (Cl−, Br−) can significantly enhance the absorption intensity. Under the optimized experimental conditions, this method exhibits a good linear response range for Cu2+ from 0.5 to 100 μM, with the detection limit of 93 nM. Moreover, the possible detection principle has been explored. It is worth mentioning that the color change can be clearly observed by naked eyes for the detection of 1 μM Cu2+, which is far below the threshold limit of Cu2+ in drinking water suggested by World Health Organization. It means that this method possess great promise for on-site Cu2+ detection.

Apatite, Ca10(PO4)6(OH,F,Cl)2: Structural Variations, Natural Solid Solutions, Intergrowths, and Zoning

Thirty-three samples from natural apatite (Ap) solid solutions, ideal structural formula [9]Ca12[7]Ca23([4]PO4)3[3](F,OH,Cl), (Z = 2) were examined with electron-probe microanalysis, synchrotron high-resolution powder X-ray diffraction (HRPXRD), and Rietveld refinements. Apatite has space group P63/m for the general chemical formula above. In Ap, the two different Ca sites are generally occupied by Ca, Mn, Sr, Na, or REE3+ cations; the P site is occupied by P, Si, or S, and the X is occupied by F, OH, Cl, O2−, or (CO3)2− anions. However, it may be possible for CO32− + F− anions to partially replace PO43− groups. In this study, the unit-cell parameters a, c, and c/a ratio, vary smoothly and non-linearly with the unit-cell volume, V. The data falls on two distinct trend lines. The average &lt;P-O&gt;[4] distance is nearly constant across the Ap series, whereas the average &lt;O-P-O&gt;[6] angle decreases linearly. The coordination numbers for the atoms are given in square brackets in the general chemical formula above. The average &lt;Ca1-O&gt;[9], &lt;Ca2-O&gt;[6], &lt;Ca2-O,X&gt;[7], and Ca2-X distances change non-linearly with increasing V. Although Cl− anion is larger than OH− and F− anions, the c unit-cell parameter in F-Ap is larger than that in Cl-Ap. In Cl-Ap, the Ca2 polyhedra are larger than in F-Ap, so the O and Cl anions are under-bonded, which cause the Ca1 polyhedra to contract and charge balance the anions. Alternatively, the Ca1 polyhedra are smaller in Cl-Ap than in F-Ap, so the Ca1 polyhedra in Cl-Ap cause the c axis to contract compared to that in F-Ap.

One-step supramolecular fabrication of ionic liquid/ZIF-8 nanocomposites for low-energy CO2 capture from flue gas and conversion

High-efficient capture of CO2 from flue gas at discharged temperatures (100–120 °C) and convert CO2 under mild condition is of vital importance for low energy consumption and emission reduction, which yet remains a great challenge. A one-step supramolecular strategy for incorporating amino-functionalized ionic liquids (AFILs) into ZIF-8 is proposed for capture and conversion of CO2 from flue gas at discharged temperatures. AFILs are attached through metal-coordination interaction between Zn (II) and the NH2 group on AFIL, by which the large BET surface area and high thermal stability inherited from ZIF-8 are maintained well. The nanocomposites with low IL consumptions can rapidly capture CO2 from the flue gas with a high capacity of 2.68 mmol·g−1 within 4 min and efficiently catalyze CO2 into cyclic carbonates with excellent yield (95.6%) and selectivity (97.0%) at 40 °C and 0.1 MPa. In-situ DRIFTS and DFT calculation elucidated the effective synergistic mechanism of multiple active sites (C2-proton on imidazolium ring, imidazolium cation, protons of methyl group, protons of methylene group, Cl anion and Zn (II)) for CO2 adsorption and conversion. The activities in both the CO2 capture and conversion can be easily recycled, endowing the nanocomposites with outstanding practical potentials.