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Dolomite collected from Surat Thani Province in Thailand was investigated for use as a sorbent for the removal of divalent heavy metal cations from an aqueous solution. The sorbent had a surface area of 2.46 m2/g and a pH of zero point charge (pHzpc) of 9.2. Batch sorption was used to examine the effect of the pH (pH 3–7) on the sorption capacity of Cd2+, Pb2+ and Zn2+, alone or together as an equimolar mixture at various concentrations. Alone, each heavy metal cation was adsorbed faster at a higher pH, where the sorption of Cd2+ and Pb2+ fitted a Langmuir isotherm, but Zn2+ sorption best fitted a Freundlich isotherm. Under equimolar competitive sorption, the sorption capacity of each cation was decreased by 75.8% (0.29–0.07 mM/g), 82.8% (0.53–0.09 mM/g), and 95.7% (0.84–0.04 mM/g) for Cd2+, Pb2+ and Zn2+, respectively, compared to that with the respective single cation. Desorption of these heavy metal cations from dolomite was low, with an average desorption level of 0.06–17.4%. Furthermore, sinc...

Iron-doped, nickel oxyhydroxide (Ni(Fe)OOH) is one of the best catalysts for the oxygen evolution reaction (OER) under alkaline conditions. Due to Ni(Fe)OOH’s layered structure, electrolyte species are able to easily intercalate between the octahedrally coordinated sheets. Electrolyte cations have long been considered inert spectator ions during electrocatalysis, but electrolytes that penetrate into the catalyst may play a major role in the reaction process. In a joint theoretical and experimental study, we report the role of electrolyte counterions (K+, Na+, Mg2+, and Ca2+) on Ni(Fe)OOH catalytic activity in alkaline media. We show that electrolytes containing alkali metal cations (Na+ and K+) yield dramatically lower overpotentials than those with alkaline earth cations (Mg2+ and Ca2+). K+ and Na+ lower the overpotential because they have an optimal acidity and size that allows them to not bind too strongly or alter the stability of reaction intermediates. These two features required for intercalated ca...

A luminescent terbium(III)-based coordination polymer, [Tb(BTEC)0.5(HCOO)(H2O)2] (1) has been successfully synthesized by solvothermal reaction of Tb(NO3)3·6H2O with 1,2,4,5-tetracarboxylic acid (H4BTEC) in N,N-dimethylformamide (DMF) and H2O at 160 °C. Compound 1 possesses dimeric [Tb2(BTEC)4(HCOO)2(H2O)4] building blocks which are linked by BTEC linkers to generate a two-dimentional honeycomb layer. 1 shows intense characteristic green emission in both solid state and organic solvents including acetone, ethanol, acetonitrile, benzene, dichloromethane, methanol, tetrahydrofuran, dimethyl sulfoxide and water at ambient temperature. Strong emission of 1 could be highly and selectively quenched by 4-nitropenol (4-NP) even in the coexistence of other competing nitroaromatics such as 2,4,6-trinitrophenol, 2,6-dinitrotoluene, nitrobenzene, 4-nitrotolune, 4-bromophenol, phenol, bromobenzene, and 1,2-dimethylbenzene. In addition, 1 exhibited superior selectivity and sensitivity towards Fe3+ ion over other metal ions including Al3+, Ca2+, Cd2+, Co2+, Cr3+, Cu2+, Ni2+, K+, Mg2+, Mn2+, Pd2+ and Zn2+ ions. The possible detection mechanisms have been proposed. More interestingly, the trace amounts of 4-NP and Fe3+ ions were selectively detected using visual luminescent test papers based on 1, which could further contributes a credible potential sensing application of coodination polymers for the biological and environmental concerns.

Single and multi-component adsorptive removal of 134Cs+, 60Co2 + and 152 + 154Eu3 + from aqueous solutions onto sepiolite are studied in the present study. Removal of these radionuclides in single systems is found to be strongly dependent on the initial pH on the solution. Removals > 99% (for 60Co2 + and 152 + 154Eu3 +) and of about 82% (for 134Cs+) are achieved at initial pH values higher than 4 and 5, respectively. The kinetic data and the equilibrium isotherms are modeled by two kinetic models, the pseudo-first-order and the pseudo-second-order, and two isotherm models, Langmuir and Freundlich, respectively. The effect of various coexisting cations, Na+, Ca2 + and Al3 +, at different concentrations on the adsorption processes of the concerned radionuclides in single systems was evaluated. Desorption studies of radionuclide-loaded sepiolite are studied using different concentrations of organic, EDTA and HA (strong complexing agents for radionuclides), and inorganic, HCl, NaCl, CaCl2, Mg(NO3)2 and AlCl3, desorbing agents. Adsorption mechanisms of radionuclides onto sepiolite are deeply discussed. Multi-component adsorptive removal of 134Cs+, 60Co2 + and 152 + 154Eu3 + onto sepiolite as a function of adsorbent weight and time was also studied. The influence of the solution pH on co-removal efficiency of radionuclides was investigated in presence of EDTA. Furthermore, the present investigation evaluated the removal efficiency of radionuclides, in multi-systems, in presence of different concentrations either of NaCl or CaCl2.

Amine-functionalized magnetic iron oxide nanoparticles (MIONPs-NH 2 ) were successfully synthesized via a simple method, which exhibited excellent adsorbents properties for cationic-type heavy metals. The adsorption and desorption performances of Cu 2+ , Zn 2+ , Cd 2+ , Pb 2+ and Ni 2+ were fully investigated in detail and the possible adsorption mechanism was proposed on the basis of various characterizations as well as the adsorption priority. As a result, the MIONPs-NH 2 could remove metal cations rapidly depending on the complexation of amino groups on surface and the adsorption was both sensitive to pH and ionic strength. Moreover, the corresponding competitive adsorption processes and desorption experiments indicated that the as-synthesized sample has the strongest affinity and adsorption priority for Pb 2+ , followed by Cu 2+ and Zn 2+ , and finally by Cd 2+ and Ni 2+ . The present study may provide a helpful direction for the application of the MIONPs-NH 2 in wastewater treatments involving multiple heavy metal cations.

Nano-birnessite was prepared, characterized and used for removal of cobalt and strontium ions from aqueous solutions. Scanning electron microscope and atomic force microscope images indicated that the particles of the prepared material are presented in the nano-scale form, the grain size was found in a range of 58–95 nm. Specific surface area of the prepared nano-birnessite was determined and found to be 200.54 m2/g. The Capacities of nano-birnessite for cobalt and strontium are 2.97 and 3.04 meq/g, respectively. The kinetic studies indicated that the sorption of the two ions obeys pseudo-second-order model and controlled by an intra-particle diffusion mechanism. The diffusivity of Co2+ and Sr2+ ions onto nano-birnessite was determined and indicated that the sorption is chemisorption process. Hence, nano-birnessite material is an efficient sorbent and can be used to decrease the influx of pollutants, such as; Co2+ and Sr2+ ions to the environment or their removal from contaminated media.

Two low cytotoxic fluorescence probes Rb1 and Rb2 detecting Fe 3+ were synthesized and evaluated. Rb1 and Rb2 exhibited an excellent selectivity to Fe 3+ , which was not disturbed by Ag + , Li + , K + , Na + , NH 4 + , Fe 2+ , Pb 2+ , Ba 2+ , Cd 2+ , Ni 2+ , Co 2+ , Mn 2+ , Zn 2+ , Mg 2+ , Hg 2+ , Ca 2+ , Cu 2+ , Ce 3+ , AcO − , Br − , Cl − , HPO 4 2− , HSO 3 − , I − , NO 3 − , S 2 O 3 2− , SO 3 2− and SO 4 2− ions. The detection limits were 1.87 × 10 −7 M for Rb1 and 5.60 × 10 −7 M for Rb2 , respectively. 1:1 stoichiometry and 1:2 stoichiometry were the most likely recognition mode of Rb1 or Rb2 towards Fe 3+ , and the corresponding OFF–ON fluorescence mechanisms of Rb1 and Rb2 were proposed.

The doping of aluminum (Al3+) and the co-doping of aluminum (Al3+)/fluoride (F−) into cadmium sulfide-montmorillonite were investigated. The Al3+ doping was achieved by the reactions between Al3+/Cd2+-montmorillonite and an aqueous solution of sulfide (S2−). The doping of F− was conducted by the reactions between the Al3+ doped sample and an aqueous solution of sodium fluoride (NaF) at room temperature. The products were characterized by powder X-ray diffraction, transmission electron microscopy, as well as Raman, UV–visible and photoluminescence spectroscopies. The blue-shift of the absorption onset and the emission band, as well as the increase in the photoluminescence intensity of the Al3+ doped and Al3+/F− co-doped CdS in montmorillonite if compared with pure CdS and CdS in montmorillonite were ascribed to quantum size effect and Burstein–Moss effect.

We have recently developed new Eu 2+ -doped Na 2 O–Al 2 O 3 –SiO 2 glasses by heating precursors in H 2 gas, in which Al 3+ ions play an important role in reducing Eu 3+ to Eu 2+ . However, the pathway by which the Eu 3+ ions are reduced was not established. To address this question, the structural changes involving Al 3+ and Eu 3+ ions have been elucidated from Magic-Angle Spinning Nuclear Magnetic Resonance (MAS NMR) in solid state and X-ray absorption fine-structure spectroscopies. In the glasses with Al/Na >1, the Al 3+ ions form AlO 4 units without incorporating Na + ions for charge compensation, and the Eu 3+ ions are coordinated by a network structure comprising AlO 4 and SiO 4 . When heated in H 2 gas, the H 2 gas molecules diffuse and react with the Eu 3+ ions, reducing them to Eu 2+ and forming O–H bonds. The diffusion rate of H 2 molecules was analyzed from the formation process of O–H bonds; 3.37×10 −12 m 2 /sec at 700 °C and 39.5 kJ/mol for diffusion coefficient and activation energy, respectively.

Several kinds of hydroxyapatites (HAp) prepared by modification of Ca2+-HAp with transition metal (Fe2+, Fe3+, Co2+, Ni2+, Cu2+ and Zn2+) or aluminum (Al3+) ions were evaluated via a gas bag-detection tube method whether they could be used as novel deodorant materials. The samples treated with divalent cation (Fe2+, Co2+, Ni2+, Cu2+ and Zn2+) retained hydroxyapatite structure as well as Ca2+-HAp, whereas those treated with trivalent cation (Al3+ and Fe3+) showed lower crystallinity than Ca2+-HAp. 5–8 wt% cation of the samples was introduced by modification with divalent metal cations, whereas about 40 wt% cation of the samples was introduced with relatively larger surface area and higher content of adsorbed water for trivalent cations. For NH3 gas, modification of Ca2+-HAp with a divalent metal cation enhanced its adsorption ability, and that with a trivalent metal cation resulted in considerable improvement of the ability. On the other hand, modification of Ca2+-HAp with Cu2+ ion gave it remarkable H2S gas adsorption ability in comparison to that with other metal cations. However, adsorption ability for H2S of some polycrystalline powders including Cu2+ was not higher than that of Cu2+-modified HAp. The effect of the incorporated cation on adsorption ability for NH3 molecules may be based not only on a simple Lewis acid-base reaction but also on specific surface area and adsorbed water content, and the effect for H2S molecules based on the specific local electron density around the cation present on/in the material.

To remove cesium ions from water and soil, a novel adsorbent was synthesized by following a one-step co-precipitation method and using non-toxic raw materials. By combining ammonium-pillared montmorillonite (MMT) and magnetic nanoparticles (Fe3O4), an MMT/Fe3O4 composite was prepared and characterized. The adsorbent exhibited high selectivity of Cs+ and could be rapidly separated from the mixed solution under an external magnetic field. Above all, the adsorbent had high removal efficiency in cesium-contaminated samples (water and soil) and also showed good recycling performance, indicating that the MMT/Fe3O4 composite could be widely applied to the remediation of cesium-contaminated environments. It was observed that the pH, solid/liquid ratio and initial concentration affected adsorption capacity. In the presence of coexisting ions, the adsorption capacity decreased in the order of Ca2+>Mg2+>K+>Na+, which is consistent with our theoretical prediction. The adsorption behavior of this new adsorbent could be expressed by the pseudo-second-order model and Freundlich isotherm. In addition, the adsorption mechanism of Cs+ was NH4+ ion exchange and surface hydroxyl group coordination, with the former being more predominant.

A new heterocyclic thiophene-2-caboxylic acid hydrazide based chemosensor R1 to R4 were designed, synthesized and characterized by various spectroscopic techniques like FT-IR, UV-Vis, 1H NMR, 13C NMR, Mass and SC-XRD. The chemosensor R3 showed a significant color change from colorless to yellow in the presence of Cu2+ ions and chemosensor R4 showed a significant color change from colorless to yellow in the presence of Cd2+ ions over the other tested cations such as Cr3+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Zn2+, Ag2+, Al3+, Pb2+, Hg2+, K+, Ca2+ and Mg2+. The high selective and sensitivity of R3 towards Cu2+ and R4 towards Cd2+ ions was confirmed by UV-Vis spectroscopic study. The R3 showed a red shift in the presence of Cu2+ ions by Δλmax 67 nm and R4 showed a red shift in the presence of Cd2+ ions by Δλmax 105 nm in the absorption spectrum. The binding stoichiometric ratio of the complex between R3 - Cu2+ and R4 - Cd2+ ions have been found to be 1:1 using the B-H plot. Under optimized experimental conditions, the R3 and R4 exhibits a dynamic linear absorption response range, from 0 to 50 μM for Cu2+ ions and 0 to 30 μM for Cd2+ ions, with the detection limit of 2.8 × 10−6 M for Cu2+ and 2.0 × 10−7 M for Cd2+ ions. The proposed analytical method for the quantitative determination of Cu2+ and Cd2+ ions was validated and successfully applied for the environmental samples with good precision and accuracy.

Sequential fluorescence sensing of Zn 2+ /Cd 2+ ions and phosphate anion by new quinoline based sensors(L1 and L2) have been presented. Sensors exhibit highly selective fluorescence “turn-on” sensing properties to Zn 2+ /Cd 2+ ions in CH 3 OH/H 2 O(1/1, v/v, Tris, 10 mol·L −1 , pH 7.4) solution with a 1:1 binding stoichiometry. The complexes display high selectivity to H 2 PO 4 - and HPO 4 2- anions through fluorescence “turn-off” respond. The results of Zn 2+ /Cd 2+ ions and phosphate anion sequential recognition via fluorescence changes make sensors L1 and L2 have potential utility for Zn 2+ / Cd 2+ ions and phosphate anion detection in aqueous media.

Copper ions (Cu2+ and Cu+) have shown potential as Fenton-like activators for the circumneutral removal of organic contaminants from aqueous solutions. However, the major active species (cupryl species (Cu3+) versus hydroxyl radical (OH)) produced during the activation of hydrogen peroxide by Cu+ remain unclear. In this study, Cu+-O2 oxidation, in which hydrogen peroxide is produced via the activated decomposition of dissolved molecular oxygen, was used to degrade sulfadiazine, methylene blue, and benzoic acid. The results showed that both sulfadiazine and methylene blue could be efficiently degraded by Cu+-O2 oxidation in a wide effective pH range from 2.0 to 10.0. Quenching experiments with different alcohols and the effect of Br- suggested that Cu3+ rather than OH was the major active species. Electron paramagnetic resonance detected 5,5-dimethyl-2-hydroxypyrrolidine-N-oxyl (DMPO-OH), which was probably produced by the oxidation of DMPO by Cu3+ or OH formed as a product of Cu3+ decomposition. 4-hydroxybenzoic acid was produced during the degradation of benzoic acid by Cu3+. The findings of this study may help to explain the inconsistency regarding the dominant active species produced by the interaction of Cu+ and hydrogen peroxide.

A series of colorimetric chemosensors R1-R6 have been developed from thiocarbohydrazide derivatives, for the selective detection of heavy metal ions. The structures of the receptors R1-R6 were well characterized by standard spectroscopic techniques like FT-IR, 1H NMR, and ESI-MS. The solid structure of receptor R1 and R2 were derived by single crystal X-ray diffraction (SC-XRD). The cation reorganization abilities of receptors R1-R6 were studied by UV-Vis spectroscopy. The receptors R1, R3 and R4 acts as a tremendous sensitive probe for heavy metal ions (Hg2+, Cd2+ and Pb2+) with the μM detection (R1 for Hg2+, 2.72, R3 for Cd2+, 3.22, R4 for Hg2+, Cd2+ & Pb2+, 0.70, 0.20 & 0.30μM) and the receptors R2, R5 &R6 are sensitive towards Cu2+ ions with the μM detection (3.34, 0.90 & 1.20μM) in an aqueous medium among all other tested cations. The receptor R4 shows a multi-color response towards Hg2+, Cu2+, Cd2+ and Pb2+ ions. The recognition mechanism, stoichiometric binding ratio and detection limit (DL) have been examined by UV-Visible spectroscopic titration experiments and Benesi-Hildebrand (B-H) plot, receptor R1-R6 sowed 1:1 binding ratio with good binding constant range of 103 to 105M-1 with Hg2+, Cu2+, Cd2+ and Pb2+ ions metal ions.

Schiff base sensors have the advantage of being used through easy, fast, cost-effective and reliable optical methods for sensing toxic metal ions in the environment. In this work, a, simple but highly specific benzildihydrazone based smart probe (1E,2E)-1,2-diphenyl-1,2-bis((E)-(pyridin-2-ylmethylene)hydrazono)ethane (L) has been used for colorimetric detection of Cu2+ at physiological pH range. Binding interaction between L and various metal ions has been established by UV–Vis spectroscopic measurements, showing favourable coordination towards Cu2+ and almost no interference with the presence of other metal ions, i.e., Na+, K+, Mg2+, Ba2+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+, Cd2+, Pb2+ Ag+ and Al3+. L exhibited binding-induced colour change from colourless to reddish yellow with a detection limit of 3.66 × 10−7 M, measured by spectroscopic methods, while colorimetric changes could be observed at naked eye for concentrations as low as 2.5 × 10−6 M. L has been successfully applied for the determination of Cu2+ in real samples.

Enthalpies of complex formation for glycine (HL±) with Ce3+ and Er3+ ions at 298.15 K and the value of the ionic strength of 0.5 (KNO3) are determined by calorimetric means using two independent procedures. Thermodynamic characteristics of the reactions of formation for complexes of glycine with Ce3+ and Er3+ ions at various [metal]: [ligand] molar ratios are calculated.

Water pollution is a worldwide issue for the eco-environment and human society. Removal of various pollutants including heavy metals from the environment is a big challenge. Techniques of adsorption are usually simple and work effectively. In the current study, MWCNTs were prepared by chemical vapor deposition (CVD) of acetylene at 600 °C. Fe–Co/CaCO3 catalyst/support was prepared by wet impregnation method. The crystal size of the catalyst was identified using XRD. Acidified functionalized multi-walled carbon nanotubes (MWCNT) were produced from oxidation of multi-walled carbon nanotubes by mixture of H2O2 + HNO3 in a ratio of 1:3 (v/v) at 25 °C. The structure and purity of synthesized functionalized CNTs were examined by TEM, N2-BET method and thermogravimetric analysis. The functional groups produced at CNTs surface were investigated using FTIR spectroscopy. Acidified functionalized MWCNTs with a high surface area of 194 m2g−1 and porous structure (17.19 nm) were used for water treatment from harmful cations (Pb2+, Cu2+, Ni2+ and Cd2+), single cation solutions and quaternary solution at different pH values and different times. The results were interesting because in single solutions the catalyst removed Pb2+, Ni2+, Cu2+ and Cd2+ with percentages of 93, 83, 78 and 15%, respectively, in 6 h. While in quaternary solution, adsorption was more complex and the order of the adsorbed metals was as following: Pb2+ (aq) > Cu2+(aq) > Cd2+ (aq) > Ni2+ (aq).

A series of K2TiF6:Mn4+, M2+ samples were prepared by the cation exchange method. Experimental results indicate that Mn4+ and Ti4+ can be quantitatively exchanged. Doped effects of M2+ (M = Mg, Ca, Sr, Ba, and Zn) on the fluorescent properties of the samples were discussed. The results indicated that the most intensities of the PLE and PL peaks come from a blank sample (K2TiF6:0.0253Mn4+). The sample of K2TiF6:0.0253Mn4+ contains perfect hexagonal phase micro-sticks with sizes about 0.5 × 0.5 × 3.0 μm, which its decay lifetime and the photoluminescence quantum yields are 5.2 ms and 94.04%, respectively. The chromaticity coordinates of K2TiF6:0.0253Mn4+ indicated that this phosphor was a potential candidate as a red-emitting component for blue light excited white LED devices. The method described here is a potential candidate for large-scale synthesis of K2TiF6:Mn4+ micro-sticks.

In order to achieve an effective “turn-on” fluorescence detection of Cu2+, a rhodamine 6G-based sensor [1-phenyl-3-methyl-5-hydroxypyrazole-4-benzoyl(rhodamine 6G) hydrazone, 1] was prepared. Fluorescence and UV–Vis absorption titration, detection limit, single crystal structure, binding mode, and quantum mechanical calculation studies were also discussed in detail. Sensor 1 showed highly selectivity and sensitivity to Cu2+ among common cations (Na+, K+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, Zn2+, Cd2+, Cr3+, Fe3+ and Cu2+) in acetonitrile. Upon addition of Cu2+, a new absorption band at 523 nm, and a strong emission band centering at 557 nm appeared in 1 solution. Relevant solution changed from colorless to purple, and an obvious orange fluorescence emission was given. A maximum fluorescence enhancement of 250 times at 557 nm could be made by addition of 6 equivalent of Cu2+. The fluorescence detection limit was calculated to be 2.5 μM (0.20 ppm) for Cu2+, and 1:1 stoichiometry between Cu2+ and 1 was proved. In the single crystal of 1–Cu2+ complex, rhodamine moiety exhibited an open cycle form. We believe 1 can be a good candidate for the fluorescence detection of Cu2+.

In this study, iron oxide-vermiculite composite (Iovc) with a high specific surface area (SSA) was prepared to remove Ni 2 + and Cu 2 + from aqueous solution. It was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared (FTIR), and scanning electron microscopy (SEM). The effects of initial pH of the solution, contact time and adsorbent concentration on the adsorption efficiency were investigated systemically. Equilibrium adsorption isotherms were measured for the single component by using various models. The homogenous adsorption of Ni 2 + and Cu 2 + was confirmed in the single system by Langmuir and Koble–Corrigan models. For the binary adsorption of Cu 2 + and Ni 2 + ions have been analyzed by using non-modified Langmuir, modified Langmuir, extended Langmuir, extended Freundlich and Sheindorf–Rebuhn–Sheintuch (SRS) models. The competitive extended Langmuir model described well the competitive adsorption of Ni 2 + and Cu 2 + . Maximum adsorption capacities for Ni 2 + and Cu 2 + in the binary system are 101.3 and 59.7 mg/g, respectively. In the kinetic study, the experimental data fitted well the pseudo-second-order kinetics for Ni 2 + and Cu 2 + adsorption data. Furthermore, calculated thermodynamic parameters, ΔG°, ΔH° and ΔS° of adsorption showed that the adsorption of Ni 2 + and Cu 2 + was feasible, spontaneous and an exothermic process.

Desorption technology is important to fabricate the economical process for Li + recovery from brine by adsorption method, but there have been no systematic studies on the column Li + desorption. The purpose of this paper is to find the elution conditions to have the eluate with high Li + concentration in a short time, from which Li 2 CO 3 can be precipitated without pre-concentration. The promising conditions of column Li + desorption could be proposed on the bases of column desorption experiments and model calculations. The natural salt brine (pH 6.8) containing 0.21 M (1 M = 1 mol dm − 3 ) Li + , 2.7 M Na + , 0.51 M K + , 1.3 M Mg 2 + , 5.4 M Cl − , and 0.25 M SO 4 2 − was used for the Li + adsorption. The granulated adsorbent sieved to 0.42–0.71 or 0.71–1.0 mm was prepared with colloidal silica as a binder. The Li + -loaded adsorbents were prepared by treating the granulated adsorbent with the NaHCO 3 added brine by a batch method. The column elution experiments were carried out by passing HCl or H 2 SO 4 solutions with different concentrations through the Li + -loaded adsorbents at different flow rates. A model consisting of Li + migration in the solid phase and of surface H + /Li + exchange was proposed for the analysis of desorption behavior. The calculated elution curves well approximated the experimental ones when the effective acid concentration and the elution delay were considered. These approximations may be caused by the influence of the other metal ions co-adsorbed from brine. The calculation showed that the elution by passing a 2 M acid solution at a space velocity of 10/h up to 2 bed volume produces the eluate of high Li + concentration (1.15 M) with high Li + recovery (87%). This process has the advantages of eliminating the step of pre-concentration of eluate for precipitation and reducing the acid consumption.

The effect of transition metal ions (M2 + = Mn2 +, Ni2 +, Co2 +, Cu2 +) on the chemical synthesis of polyaniline (PANI) used as a platinum-free counter electrode (CE) in dye-sensitized solar cells (DSSCs) was investigated. PANI was synthesized by co-polymerization of aniline in the presence of different transition metal ions by using potassium dichromate in acidic medium. It was found that the ion doping of PANI showed a certain catalytic activity for the regeneration of traditional iodide/triiodide (I−/I3−) redox couples. The power conversion efficiency (η) of PANI CEs doped with Mn2 +, Ni2 +, Co2 + (4.41%, 2.36% and 2.10%, respectively) were higher than 1.94%, the value measured for PANI CE without doping. Doping with Cu2 + decreased the power conversion efficiency of PANI CE (PANI-Cu2 + η = 1.41%). The electrical properties of the PANI, PANI-Ni2 +, PANI-Co2 +, PANI-Mn2 + and PANI-Cu2 + were studied by cyclic voltammetry (CV), impedance (EIS), and Tafel polarization curve. The experimental results confirmed that PANI was affected by the doping of different transition metal ions (M2 + = Mn2 +, Ni2 +, Co2 +, Cu2 +). These results indicate a potential application of ion doped PANI as counter electrode in cost-effective DSSCs.

We report a facile synthetic method for high-aspect-ratio YF3:Yb3+/Er3+ nanocrystals by controlling the composition of the precursor and salts to manipulate the structures of YF3:Yb3+/Er3+ nanocrystals. A controlled aspect ratio is attained by tuning the molar ratio of NH4+/RE3+ (NH4+ is the counterion released from the fluoride precursor (NH4F) and RE3+ indicates the total amount of Y, Yb, and Er) and the presence of specific inorganic salts. A low molar ratio of NH4+/RE3+ induced the production of high-aspect-ratio YF3:Yb3+/Er3+ nanocrystals, while a high molar ratio of NH4+/RE3+ induced the formation of irregular nanoplates. The selection of the inorganic salt as an additive is critical in controlling the aspect ratio and crystallinity of YF3:Yb3+/Er3+ nanocrystals. The cation showed limited control over the aspect ratio, but the anions, Cl– and Br–, induced the production of the highest aspect ratio for YF3:Yb3+/Er3+ nanocrystals. We found that the aspect ratio affected the luminescence properties of ...

A new and dual-response fluorescent probe (QLBM) based on quinoline and benzimidazole groups has been designed and developed for recognition of copper(II) ion (Cu2+) and iron(III) ion (Fe3+) simultaneously. This sensor displays a favorable selectivity for Cu2+ and Fe3+ ions over a range of other common metal cations in 100% aqueous medium (50 mM Tris buffer, pH 7.2), leading to prominent fluorescence on-off. The detection limits were 1.35 × 10−7 M for Cu2+ and 1.24 × 10−7 M for Fe3+ respectively. This dual-response fluorescent probe for Cu2+ and Fe3+ was distinguished by further reduction of the ascorbic acid. It is reported for the first time to use ascorbic acid to discriminate Cu2+ and Fe3+ by fluorescent probe technology. The recognizing mechanism of QLBM toward Cu2+ and Fe3+ has been investigated in detail by NMR, HR-MS and density functional theory (DFT) calculations. Moreover, further application of the sensor in fluorescence imaging was studied in HeLa cells due to the low cytotoxicity and good photophysical properties, suggesting that QLBM could be used as a fluorescent sensor for tracking Cu2+ and Fe3+ in cells.

Using flow-batch analysis, a highly sensitive and selective method for automatic colorimetric detection of copper ions (Cu2+) was produced on the basis of the surface plasma resonance (SPR) of silver nanoparticles (Ag NPs). The Ag NPs were catalytically etched by thiosulfate in the presence of Cu(NH3)42+, resulting in a color change of the solution induced by the absorbance decrease at 401 nm of the SPR peak of Ag NPs. The proposed method showed high selectivity for Cu2+ over various metallic ions, including Fe3+, Mn2+, Co2+, Ni2+, Zn2+, Pb2+, Ba2+, Cd2+, Bi3+, Sb2+, As3+, Hg2+, Cr3+ and K+. The linear range was 0.5–35 μg/L with a coefficient of 0.9954. The limit of detection was as low as 0.24 μg/L. The relative standard deviation (RSD, n=7) for the determination of Cu2+ spiked samples at concentrations of 10 μg/L was 1.21% and for 25 μg/L was 1.03%. The proposed method was successfully applied to analyze Cu2+ in lake water, tap water, rainwater and bottled water samples, as well as leaf samples for food packaging. The results were in good agreement with those obtained by graphite furnace atomic absorption spectrometry, the classical technique.

A colorimetric and fluorescent probe L has been designed and synthesized, which bearing the double azine moiety and showing a detection limit of 2.725 × 10−7 M towards Zn2+. Based on the basic recognition mechanism of ESIPT and CHEF effect, the L has high selectivity and sensitivity to only Zn2+ (not Fe3+, Hg2+, Ag+, Ca2+, Co2+, Ni2+, Cd2+, Pb2+, Cr3+, and Mg2+) within the physiological pH range (pH = 7.0–8.4) and showed a fluorescence switch. Moreover, this detection progress occured in the DMSO/H2O ∼ HEPES buffer (80/20, v/v; pH 7.23) solution which can conveniently used on test strip., Graphical abstract A colorimetric and fluorescent probe L has been designed and synthesized, bearing the double azine moiety and showing a detection limit of 2.725 × 10−7 M towards Zn2+. Based on the basic recognition mechanism of ESIPT and CHEF effect, the probe owes high selectivity and sensitivity to only Zn2+ (not Fe3+, Hg2+, Ag+, Ca2+, Co2+, Ni2+, Cd2+, Pb2+, Cr3+, and Mg2+) within the physiological pH range (pH = 7.0–8.4) and showed a fluorescence switch. Moreover, this detection progress occur in the DMSO/H2O ∼ HEPES buffer (80/20, v/v; pH 7.23) solution which can conveniently used on test strip, and it can anti interference of others.Image 1

The reaction of copper and silver cations with carbon dioxide was studied by mass-selected infrared photodissociation spectroscopy. Quantum chemical calculations were performed on these products, which aided the experimental assignments of the infrared spectra and helped to elucidate the geometrical and electronic structures. The Cu+ and Ag+ cations bind to an oxygen atom of CO2 in an end-on configuration via a charge-quadrupole electrostatic interaction in the [M(CO2)n]+ complexes. The formation of oxide-carbonyl and carbonyl-carbonate structures is not favored for the interaction of CO2 with Cu+ and Ag+. For n = 3 and 4, the n + 0 structure is preferred. [Note on the nomenclature: Using i + j, i denotes the number of CO2 molecules in the first coordination shell, and j denotes the number of CO2 molecules in the second coordination shell.] The two nearly energy-identical n + 0 and (n – 1) + 1 structures coexist in n = 5 and 6. While the six-coordinated structure is favored for [Cu(CO2)n=7,8]+, the n + 0 ...

A novel organic–inorganic hybrid nanomaterial (SBA-15-CA) was prepared by covalent immobilization of chromotropic acid onto the surface of mesoporous silica material SBA-15. Different techniques such as XRD, TEM, FT-IR, N2 adsorption–desorption and TGA analyses were employed to characterize the grafting process. The data showed that the organic moiety (0.41 mmol g−1) was successfully grafted to the SBA-15 and the primary hexagonally ordered mesoporous structure of SBA-15 was preserved after the grafting procedure. SBA-15-CA has been realized as a highly sensitive and selective fluorescent probe towards Fe3+ and I− ions in aqueous media. SBA-15-CA exhibited a remarkable fluorescent quenching in the presence of Fe3+ ion over other competitive cations including Na+, Mg2+, Al3+, K+, Ca2+, Cr3+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, and Pb2+ as well as I− ion among a series of anions including F−, Cl−, Br−, CO3 2−, HCO3 −, CN−, NO3 −, NO2 −, SCN−, SO4 2−, H2PO4 −, HPO4 2−, and CH3COO−. A good linear response was observed between the concentration of the quenchers (Fe3+ and I− ions) and fluorescence intensity of SBA-15-CA with detection limits of 1.5 × 10−7 M for Fe3+ and 0.2 × 10−7 M for I−. Moreover, the effects of various pH values on the sensing ability of SBA-15-CA were investigated. Finally, the proposed method was successfully utilized for the determination of Fe3+ and I− ions in river water, well water and tap water samples.

The equilibrium constants for [NpO2·M]4+ (M = Al3+, In3+, Sc3+, Fe3+) in μ = 10 M nitric acid and [NpO2·Ga]4+ in μ = 10 M hydrochloric acid media have been determined. The trend in the interaction strength follows: Fe3+ > Sc3+ ≥ In3+ > Ga3+ ≫ Al3+. These equilibrium constants are compared to those of previously reported values for NpO2+ complexes with Cr3+ and Rh3+ within the literature. Thermodynamic parameters and bonding modes are discussed, with density functional theory and natural bond orbital analysis indicating that the NpO2+ dioxocation acts as a π-donor with transition-metal cations and a σ-donor with group 13 cations. The small changes in electron-donating ability is modulated by the overlap with the coordinating metal ion’s valence atomic orbitals.

A new composite adsorbent, zeolite-supported microscale zero-valent iron (Z-mZVI) was evaluated as a potential adsorbent for the removal of Cd2+ and Pb2+ from aqueous solution using batch and column experiments. Adsorption isotherms were well fitted by Langmuir model, and the maximum adsorption capacity was 63.14 mg/g for Cd2+ and 154.61 mg/g for Pb2+, respectively. Both adsorption processes followed the pseudo-second-order model which indicated that the rate-limiting step for different initial concentration was dominated by chemical adsorption process. The coexistence of Cd2+ and Pb2+ caused the reduction of Cd2+ removal efficiency, but not for Pb2+. Z-mZVI has a high removal capacity for Cd2+ and Pb2+ over a wide pH range (3.0–6.8) as well as in the presence of competitive Ca2+ or Mg2+ ions (

Chloronium cations in their salts (CnH2n+1)2Cl+{CHB11Cl11–}, with n = 1 to 3 and exceptionally stable carborane anions, are stable at ambient and elevated temperatures. The temperature at which they decompose to carbocations with HCl elimination (below 150 °C) decreases with the increasing n from 1 to 3 because of increasing ionicity of C–Cl bonds in the C–Cl+–C bridge. At room temperature, the salts of cations with n ≥ 4 [starting from t-Bu2Cl+ or (cyclo-C5H11)2Cl+] are unstable and decompose. With decreasing chloronium ion stability, their ability to interact with chloroalkanes to form oligomeric cations increases. It was shown indirectly that unstable salt of fluoronium ions (CH3)2F+(CHB11F11–) must exist at low temperatures. The proposed (CH3)2F+ cation is much more reactive than the corresponding chloronium, showing at room temperature chemical properties expected of (CH3)2Cl+ at elevated temperatures.

A glycolamide-functionalized ionic liquid (G-FIL) was synthesized for the first time and was evaluated for the extraction of actinide ions such as Am3+, Pu4+ and UO22+ and fission product element ions such as Eu3+, Sr2+ and Cs+. The extraction of the trivalent metal ions was found to be exceptionally high at low acid concentrations, which rapidly decreased with increasing acidity. In view of the high viscosity of the G-FIL, the studies were carried out using its diluted solution in a commercial ionic liquid, viz. 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim][Tf2N]).

AMH-3 is a zeolite-like material with a three-dimensional uniform porous structure, layered structure, and abundant exchangeable cations. Herein, the use of AMH-3 to remove heavy metals present in aqueous solutions is investigated for the first time. Pristine AMH-3 and metal-sorbed AMH-3 were characterized with inductively coupled plasma atomic emission spectroscopy (ICP-AES), field emission scanning electron microscopy (FE-SEM), 29 Si cross polarization magic angle spinning nuclear magnetic resonance spectroscopy (CP MAS NMR) and X-ray diffraction (XRD). The removal of heavy metals by AMH-3 was found to be governed by ion exchange rather than surface adsorption, and no significant change occurred in the structure of the AMH-3 during the ion exchange. The removal of various heavy metal ions (Pb 2+ , Cu 2+ , Cd 2+ , and Zn 2+ ) onto AMH-3 from aqueous solutions was conducted using a batch method. The effects of influential parameters, such as the initial metal ion concentration and contact time, on the sorption process were studied. The metal ion sorption capacity and removal efficiency were mainly dependent on the difference between the effective pore size of the AMH-3 and the hydrated radius of the metal ion. The sorption isotherm data were well fitted by Langmuir (for Pb 2+ , Cu 2+ , and Zn 2+ ) and Freundlich (for Cd 2+ ) models. The sorption kinetics data were well fitted by a pseudo-secondorder kinetic model. Competitive sorption experiments revealed an order of metal ion affinity of Pb 2+ > Cu 2+ > Zn 2+ > Cd 2+ . These findings indicate that AMH-3 is suitable for the efficient and selective removal of heavy metals from aqueous solutions.

This work investigated the mechanism and limit of cation adsorption by reconstruction of calcined layered double hydroxide (CHT) for the first time. Mg x Al-CHT was used to adsorb Zn 2+ and Ni 2+ from aqueous solution. As a result, adsorption amount of cation was approximately equal to dissolved amount of Mg 2+ from CHT. In other words, the molar ratio was close to 1:1 between exchanged cation (Zn 2+ or Ni 2+ ) and released Mg 2+ . Besides, Zn 2+ adsorption and Mg 2+ dissolution took place synchronously until equilibrium. XRD and SEM indicated that CHT rebuilt layered double hydroxide (LDH) after adsorbing Zn 2+ and Ni 2+ . Furthermore, molar ratios of Mg 2+ /Zn 2+ and Mg 2+ /Ni 2+ were 1:1 in reconstructed CHT regardless of the original Mg 2+ /Al 3+ ratio. Based on these results, it was proposed that half of octahedral Al 3+ in LDH transformed into tetrahedral ones after calcination, resulting in half of Mg 2+ bond being distorted in CHT and ready for a potential exchange. When CHT was used to adsorb bivalent cation (Me 2+ ), the maximum amount of adsorption was the half amount of Mg 2+ , and MgMeAl-LDH was formed by dissociation-deposition.

In this study, non-apatite Ca-Mg phosphate sorbent was synthesized by neutralization method using dolomite and phosphoric acid. The mixture of crystal hydrogen phosphates of calcium and magnesium with gross composition Ca 0.7 Mg 0.3 HPO 4 ∙2H 2 O was observed in synthesized sorbent. Thermally activated dolomite was used for calcium-magnesium raw materials. The influence of sorbent dose, рН of solutions and contact time for the removal efficiency of synthesized sorbent for metal ions from aqueous solutions was studied. The maximum removal efficiency of metals was achieved at 10 g L −1 sorbent dose and рН 2.5–3.5. The sorbent is characterized by high sorption capacity in relation to ions of Zn 2+ , Cu 2+ , Pb 2+ , Cd 2+ , Ni 2+ and Co 2+ (1.19–3.78 mmol g −1 ) and a high rate of sorption (more than 90% uptake of metals ions was recorded within 3−5 min). Adsorption isotherms were built for each tested metal ions and were found to fit to Freundlich and Redlich-Peterson models. It was determined that the possible mechanism for metal ion sorption includes the dissolution-precipitation and ion-exchange stages. The present study showed that synthesized non-apatite Ca-Mg phosphate sorbent can be successfully used for the treatment of Zn 2+ , Cu 2+ , Pb 2+ , Cd 2+ , Ni 2+ and Co 2+ containing wastewater and had a significantly higher sorption capacity towards toxic metal ions than phosphate and natural materials such as activated phosphare rock, hydroxyapatite, clay minerals, dolomite.

A sensitive and highly selective, fluorescent “turn–on” fluorescence sensor for Hg2+ and Fe3+ ions are reported by using an 3,3′–dihydroxybenzidine:α–cyclodextrin (DHB:α–CD) solid inclusion complex in an acetonitrile water system. Solid inclusion complex of DHB:α–CD was prepared by co-precipitation and kneading method and it was characterized by using FTIR, 1H NMR, XRD and SEM analysis. The investigation of fluorescence spectrum revealed that the host-guest system exhibited characteristic fluorescence behavior towards Hg2+ and Fe3+ ions in acetonitrile water system. With addition of Hg2+ and Fe3+, the host-guest system shows strong fluorescence enhancement, which resulted from the fluorophore of the coordination between DHB:α–CD and metal ions (Hg2+, Fe3+) with high binding constant (k = 3.1626 × 104 M−1, 1.8225 × 104 M−1). Moreover, high selectivity experiments revealed that the fluorescent sensor is specific to Hg2+ and Fe3+ ions even with interference from higher concentrations of other metal ions. Docked structure of DHB:α–CD (molecular docking studies) fully agree with experimental data. The molecular dynamic calculations show that there are structurally and energetically favourable association among the molecules, which are in good agreement with the experimental results. Further, bioimaging studies confirmed that the DHB:α–CD shows in vitro detection of Hg2+ and Fe3+ ions in HepG2 cells.

A 8-hydroxyquinoline-based (8-HQ) fluorescent ligand ( 2 ) was designed and synthesized by condensation of pyridine-2-carboxaldehide with 2-(quinolin-8-yloxy)acetohydrazide ( 1 ). Fluorometric titrations with various metal ions in 1:1 M ratio showed that Cu 2+ and Ni 2+ ions were fully quenched the fluorescence intensity of 2 . But, a significant enhancement in the fluorescent intensity was observed when the bound Ni 2+ and Cu 2+ ions in the 2 ─Ni and 2 ─Cu complexes were displaced by Cr 3+ and Fe +2 ions, respectively. While 2 ─Ni exhibited low sensitivity toward Cr 3+ ion, the fluorescent titration measurements showed that 2 ─Cu could be a good ‘‘on-off-on’’ selective and sensitive sensor ( S ) candidate for determination of Fe 2+ in aqueous medium.

We developed a rapid high-throughput screening platform using a modified ICP-MS/MS system for monovalence metal ions catalysts discovery in azide–alkyne cycloaddition. Among the ten monovalence metal ions in the first row of periodic table containing Sc+, Ti+, V+, Cr+, Mn+, Fe+, Co+, Ni+, Cu+, and Zn+, five monovalence metal ions of Sc+, Co+, Ni+, Cu+ and Zn+ ions show relatively stronger catalytic activities than others. The catalytic mechanism of Sc+, Co+ and Ni+ ions is similar to the Cu+ ions, but Zn+ ions take a different catalytic route. A yields range of 77–98% for azide-alkyne cycloaddition was achieved with Sc+, Co+, Ni+, Cu+ and Zn+ ions as catalyst, respectively by using a UV laser ablation reactor in 20 min, notable that the yields of Co+ and Sc+ ions were even higher than the common catalyst of Cu+ ions. The proposed platform would be used not only for catalyst discovery in azide-alkyne cycloaddition, but also for the discovery of single atom/ion catalysts in other organic reactions.

Adsorbents synthesized with biopolymer have been widely used in the removal of toxic metal ions. Novel high-efficiency, recyclable, and low-cost adsorbents have received more and more attention. Chitosan and cellulose are the most abundant biopolymers in nature. Composite modified adsorbent (CSTEC) was synthesized as novel fibrous materials for the adsorption of Cu2+ and Pb2+ ions from water in this study. The functional fiber was characterized to investigate the surface appearance, functional groups, crystallinity, and thermal stability. The kinetics study revealed that adsorption processes of Cu2+ and Pb2+ ions on the CSTEC followed the second-order kinetics model. CSTEC showed better performance (Cu2+, 95.24; Pb2+, 144.93mgg-1) than most of other adsorbents. The co-existing ions (K+, Na+, Mg2+) had no significant influence on the removal of target ions by the CSTEC. The excellent reusability indicated that CSTEC had the promising application in the treatment of toxic metal pollution.

Sequestration of heavy metal ions from water is an important issue in chemistry. Herein, we report the detailed Pb2+ adsorption and ion exchange kinetics of a potassium intercalated layered metal thiophosphate, K0.48Mn0.76PS3.H2O (K-MPS-1), which is capable of efficient removal of Pb2+ (>99%) from very dilute concentrations (1–100 ppb). K-MPS-1 can selectively capture Pb2+ even in the presence of other monovalent and divalent cations such as Na+, Ca2+, and Mg2+ with high separation factor. K-MPS-1 can operate within a broad pH range of 2–12 effectively with high distribution coefficient (KdPb) of 5.36 × 105 mL/g, following pseudo second order kinetics. Initially, K+ intercalation in MnPS3 (MPS-1) increases the interlayer spacing and subsequently creates Mn2+ vacancy to maintain charge neutrality and destroy the center of symmetry of the P2S6 unit. Finally, Pb2+ kicks out K+ ions from the interlayer and sits into Mn2+ vacant sites in MPS-1 which further helps to regain the center of symmetry of the structu...

The enthalpies of complexation of glycine (HGly±) with Nd3+ and La3+ ions at 298.15 K and at an ionic strength of 0.5 (KNO3) are determined by means of calorimetry. The thermodynamic characteristics of the reactions of formation are calculated for NdGly2+, NdGly 2 + , LaGly2+, and LaGly 2 + complexes.

1,5-Naphthalenedisulfonate (1,5-NDS) intercalated MgAl layered double hydroxide (1,5-NDS-LDH) was prepared by a co-precipitation method. The 1,5-NDS-LDH was used as a functional material for removing Pb2+ from water. The XRD, IR, SEM and ICP were used to investigate the structure of the product. The prepared 1,5-NDS-LDH sample exhibited excellent removal properties for Pb2+, with a capacity up to 100.3 mg/g. Furthermore, the influences of initial pH, 1,5-NDS-LDH dosage, contact time, temperature and initial concentration of Pb2+ on the removal were also discussed. The test results reveal that the removal ability for Pb2+ is influenced by the conditions. And, the Pb2+ is removed by 1,5-NDS-LDH with the complexation of the interlayer 1,5-NDS and Pb2+ surface OH− with Pb2+. After treatment, The Pb2+ residual is about 0.04 mg/L in aqueous solution, lower than the third class of national surface water environment quality standard (≤0.05 mg/L).

In this work, the carboxylate groups terminated carbon dots (−OOC-C-dots) were synthesized by the thermal pyrolysis of citric acid at 180 °C for 40 h under air. The −OOC-C-dots with excellent water solubility showed bright blue emission under excitation at 360 nm. The blue emission fluorescence of the −OOC-C-dots can be quenched by Al3+, Hg2+, Pb2+, Ni2+, Cu2+, Cr3+, Co2+, and Fe3+ ions in HNO3 solution at pH = 5.0. Most interestingly, the −OOC-C-dots exhibited highly selective response to Fe3+ in NaAc-HAc buffer solution, to Pb2+ in Britton-Robinson buffer solution, and to Hg2+ in PBS buffer solution at pH = 5.0, respectively. Moreover, good linear relationships were found between (F0-F)/F0 and the concentrations of Fe3+, Pb2+, and Hg2+ in the corresponding buffer solutions. As a result, the −OOC-C-dots can be explored as a chemosensor for the label-free detection of Fe3+, Pb2+, and Hg2+ with selectivity being switched by different buffer systems. By the proposed method, the selective detection of Fe3+, Pb2+, and Hg2+ in real water samples (mineral and tap), even in the presence of high concentration of interfering ions, was accurately achieved. Hence, a new method for the potential detection of multi-metal ions can be developed by using one carbon-dot-based chemosensor with switchable selectivity in different buffer solutions.

Tannic acid (TA) film covered magnetic microspheres (Fe3O4@TA–Fe3+) was synthesized and applied for removal of Pb2+and Hg2+ from aqueous solution. The resulted Fe3O4@TA–Fe3+ was characterized with thermo-gravimetric analysis, vibrating sample magnetometer, transmission electron microscope, and Fourier transform infrared spectra. The adsorption of pollutants was pH dependent because the complexation of TA with Fe3+ was disassembled at low pH. The composites showed high maximum adsorption capacity for Pb2+ up to 1115.3 mg/g and Hg2+ to 279.4 mg/g. Furthermore, the Fe3O4@TA–Fe3+ composites could be easily separated from the solution by a magnet after adsorption because of the excellent superparamagnetic property. Thermodynamics study indicated that the adsorption of Pb2+ and Hg2+ on Fe3O4@TA–Fe3+ sorbents was spontaneous, chaotic degree decreasing and endothermic process. The present results warrant the promising application of magnetic Fe3O4@TA–Fe3+composites for removal of Pb2+ and Hg2+ from contaminated water, and this study is the first application of TA film in environmental remediation.

Three electronically tuned fluorescent probes ( 1–3 ) were synthesized by conjugating a fluorescent unit to N,N- bis-(hydroxyethyl)ethylenediamine. Probe 1 bearing an electron-deficient naphthalenedimide unit did not give a fluorescence response to the presence of various metal ions including monovalent metal ions (Na + , K + , and Ag + ), divalent metal ions (Ca 2+ , Cd 2+ , Co 2+ , Ni 2+ , Cu 2+ , Hg 2+ , Pb 2+ , and Zn 2+ ) and trivalent metal ions (Al 3+ , Ga 3+ , Fe 3+ , and Cr 3+ ) in an aqueous solution. By contrast, probes 2 and 3 possessing 1,8-naphthalimide and pyrene fluorophores, respectively, exhibited selective fluorescent “OFF-ON” behaviors as a result of Ga 3+ /Al 3+ binding among the diverse metal ions, suggesting the importance of fluorophore electronic character with regard to metal ion sensing. The ethylenediamine analog of probe 3 , corresponding to probe 4 , was unable to yield a significant change in fluorescence intensity in the presence of any metal ions tested here, revealing the essential role of two hydroxyl groups for metal ion binding. A high association constant of K a = 2.99 × 10 5 M −1 was obtained for probe 3 with Ga 3+ , with a limit of detection (LOD) of 10 nM. This LOD is the lowest value known for Ga 3+ detection using chemical sensors. Along with an increase in aggregate sizes, PET suppression of probes upon metal ion binding was the primary contributor to the enhancement in fluorescence emission necessary for the sensitive detection of the target ions. The probe-metal ion complexes were fully characterized via TEM, FE-SEM, 1 H NMR, fluorescence spectroscopy techniques and DFT calculations.

Ionothermal reactions of 1,3,5-benzenetricarboxylate acid (H3BTC) and Ni(NO3)2, Co(NO3)2 and Cu(NO3)2 gave two discrete 32-membered ring-like allomers, [M2(HBTC)2(NH2CONH2)2(H2O)4]·3H2O (M=Ni(1), Co(2)) and one layered [Cu2(BTC)Cl(H2O)4] (3). The weak interactions in 1 can be deconstructed to some degree in ion exchange by exploring the factors of divalent and trivalent metal species, metal concentration and soaking time, which are demonstrated by PXRD and N2 absorption. Cu2+ has the highest N2 adsorbance when soaking with 1, and 1 can keep structure stable when Cu2+ below 0.16 mol L−1 and the soaking time within 24d. As Cu2+ beyond 0.16 mol L−1 and the soaking time beyond 24d, the structure of compound 1 starts to transform with the crystal morphology from clear pale green to opaque blue. Ionothermal reactions of compound 1 with different Cu2+ amounts obtained Ni2+-Cu2+ hetero complexes, whose PXRD patterns are similar to that of 3 and EDS indicates Cu2+% increases with Cu2+ additions and close to 100% as Cu2+ being 1.6 mmol. It suggests that 3 is a controlled product and Cu2+ can transform discrete compound 1 into 2D compound 3.

A series of metallic-supramolecular ionic networks (MSINs) with Fe + 2 /Ni + 2 /Cu + 2 /Zn + 2 , ceftriaxone and dodecyl dimethyl ammonium bromide (DTAB) have been prepared and studied in aqueous and solid both states. In aqueous state the potential of pure individual solutions of Fe + 2 /Ni + 2 /Cu + 2 /Zn + 2 , ceftriaxone, DTAB, Fe + 2 /Ni + 2 /Cu + 2 /Zn + 2 + DTAB and Fe + 2 /Ni + 2 /Cu + 2 /Zn + 2 + DTAB + ceftriaxone were measured, and variations inferred their ionic interaction. For solid MSINs the same interaction has been analysed with FTIR where changes in intensity of IR peaks have been observed. The free radical scavenging activity (FRSA) of individual (metal ions, ceftriaxone, DTAB) on complexion (metal ions + ceftriaxone + DTAB) has been assessed with 2, 2-diphenyl-1-picrylhydrazyl (DPPH) in solid and aqueous both states. All MSINs have shown good antioxidant activity measured via potentiometric titration where decrease in potential was made a criterion for attributing their activity similar to spectrophotometric method. The solid MSINs have also been screened for against Gram − ve ( E. coli ; ATCC 25922) and + ve ( Staphylococcus aureus ; ATCC 33591) bacterial strains where they have shown good response. The antioxidant and antimicrobial activities of prepared MSINs show their medicinal importance.

We applied density functional calculations to study the circular redox reaction mechanism of N2O with CO catalyzed by fullerometallic cations C60Fe+ and C70Fe+. The on-top sites of six-membered rings (η6) of fullerene cages are the most preferred binding sites for Fe+ cation, and the hexagon to pentagon migration of Fe+ is unlikely under ambient thermodynamic conditions. The initial ion/molecule reaction, N2O rearrangement and N2 abstraction on the considered fullerometallic cations are easier than those on the bare Fe+ cation in the gas phase. Generally, our results indicate that fullerometallic ions, C60Fe+ and C70Fe+, are more favorable substrates for redox reaction of N2O with CO in comparison to the other previously studied carbon nanostructures such as graphene and nanotubes.

We report a highly selective method for identification and detection of iron (III) (ferric iron, Fe 3+ ) using Nile red (NR) as a complexing agent. Fe 3+ preferentially binds with NR in dimethylformamide (DMF)/water (1:1) solution over other cations such as Fe 2+ , Cu 2+ , Pb 2+ , Hg 2+ , Mn 2+ , Ni 2+ , Zn 2+ , Co 2+ and Cd 2+ at room temperature. In the presence of Fe 3+ , the color of NR solution changes from purple to dark brown, which is detectable with bare eyes. Using UV–vis spectroscopy, we could measure the amount of Fe 3+ in the sample solution by monitoring changes in absorption from 540 to 580 nm; the linear range and the limit of detection are 30–1000 µM and 24.9 µM, respectively. Taking advantage of the NR selectivity, we treated partially oxidized graphene sheets (po-Gr) with NR to obtain po-Gr-NR dispersion by ultrasonication. The NR-treated po-Gr flakes (po-Gr-NR) were characterized by UV–vis, FT-IR, and Raman spectroscopies and FE-SEM, which indicated attachment of NR on po-Gr sheets. The po-Gr-NR hybrid film deposited glassy carbon electrode (po-Gr-NR/GCE) served as the Fe 3+ sensor. Differential pulse voltammetry was used to investigate the detection of Fe 3+ in 0.05 M HCl+0.05 M KCl solution. The linear range and the limit of detection of Fe 3+ were from 37.5 nM to 21.53 µM and 18.7 nM, respectively. Furthermore, this sensor was successfully used to measure Fe 3+ content in red wine samples.