Thallous Ion Research Articles

Highly selective removal of thallous ions from wastewater using Prussian Blue biochar composite

Thallium, a highly toxic pollutant, shows greater toxicity to human than other common heavy metals such as mercury, lead, cadmium and its effective removal from wastewater gains great attention. The main restriction for the Tl+ removal is the interference of a high concentration of co-existing ions in wastewater. Therefore, the goal of the current work was to synthesis adsorbent with high selectivity for the Tl+ removal. Herein, the pore size sieving strategy was proposed and Prussian blue-impregnated biochar (BC@PB) particles was synthesized. More than 95% Tl+ can be removed even the concentrations of the coexistence ions (Na+, Cd2+, and Zn2+) 1,000 higher than the initial concentration of Tl+ (500 μg/L). BC@PB also showed large adsorption capacity (9365 μg/g) and more than 99% Tl+ (initial concentration, 500 μg/L) were removed in just 1 min. The BC@PB had excellent and stable Tl+ removal ability (> 99%) over a range of pH from 3 to 9, which covered the pH range of common thallium-containing wastewater. The density functional theory (DFT) calculation confirmed that not only hydrated volume but also the hydration free energy of ions, which governed the energy barrier for ions entering into narrow channels of BC@PB, played essential roles on the selectivity removal of Tl+. Overall, due to its high selectivity, high adsorption capacity and easy preparation process, the synthesized BC@PB particles based on the pore sizing sieving strategy, can be a promising candidate for the removal of thallium from wastewater.

Simultaneous removal of thallium and chloride from a highly saline industrial wastewater using modified anion exchange resins

Simultaneous removal of thallium (Tl) and chloride from a highly saline industrial wastewater was investigated using modified anion ion exchange resins. The removal of thallium was mainly driven by the exchange of Tl-chlorocomplex (TlCl4−) formed in the oxidation of thallous (Tl (I)) to thallic ion (Tl (III)) by hydrogen peroxide (H2O2) under saline conditions. Over 97% of thallium and chloride removal was achieved using the modified resins, with a wide optimal conditions found to be H2O2 dosage 1.0–25.0mL/L, pH 1.6–4.3, and flow rate 0.5–4.7mL/L. The modified resins had an exchange capacity of 4.771mg Tl/g dry resins for thallium and 1800mg Cl/g dry resins for chloride. Stable regeneration could be achieved with the modified resins: over 97% of thallium and 90% of chloride can be eluted using Na2SO3 solution and alternating hot (60°C) H2SO4 and cold (25°C) water, and over 98% removal of thallium and chloride was achieved after five consecutive regeneration cycles.

The Pentatin Cation in Zeolite Y: Thallous Ion Exchange and Crystal Structure of |Sn36Cl11|[Si128Al64O384]-FAU Containing Sn512+, Sn2Cl3+, and Sn3Cl5+

Sn512+, Sn2Cl3+, and Sn3Cl5+ have replaced all of the Tl+ ions in the zeolite Tl71–Y (|Tl71|[Si121Al71O384]-FAU) by thallous ion exchange (TIE), a vapor phase ion exchange method. SnCl2(g) was allowed to react with Tl71–Y under anhydrous conditions at 673 K for 48 h. The crystal structure of the product, |(Sn512+)1.70Sn2+27.4Cl–10.8|[Si127.6Al64.4O384]-FAU per unit cell, was determined by single-crystal crystallography at 294 K using synchrotron X-radiation (Fd3m, a = 24.758(1) A). It was refined with all 1465 unique data to the final error indices R1 = 0.061 and R2 = 0.208. Its composition was confirmed by scanning electron microscopy energy-dispersive X-ray analysis. Centered tetrahedral Sn512+ clusters center 21% of the sodalite cavities. About 10 Sn2+ ions per unit cell near 12-rings are bridged by Cl– ions to form five Sn2Cl3+ clusters. Similarly, six Sn3Cl5+ clusters have formed, each containing one 6-ring and two 12-ring Sn2+ ions.

Preparation, Crystal Structure, and Luminescence Properties of Zeolite LTA Containing Extraframework Tantalum(V), Tantalum(II), Thallium(I), and Chloride

For the first time pentapositive cations have been introduced into a zeolite at extraframework positions. Their presence was confirmed by single-crystal crystallography using synchrotron X-radiation and energy-dispersive X-ray analysis. It was prepared by the thallous ion exchange (TIE) method: fully dehydrated Tl12-LTA was treated with 3.0 × 104 Pa of TaCl5(g) at 473 K. The crystal structure of the product, |Ta2+0.123(TaCl6Tl3)2+0.246Tl+9.84|[Si13.4Al10.6O48]-LTA, was refined in the space group Pm3m (a = 12.099(1) A) with all unique data to the final error index R1 = 0.044 for the 639 reflections for which Fo > 4σ(Fo). TIE did not occur. Instead some TaCl5 molecules decomposed to TaCl2 and Cl2(g), and TaCl2 reacted with additional TaCl5 molecules to form Ta2+ and TaCl6–. Octahedral TaCl6– ions center about 24.6% of the large cavities. Each Cl– ion bonds to a Tl+ ion in the plane of an 8-ring to form a TaCl6Tl32+ continuum in the near-surface volume of the crystal. The Ta2+ ions, 0.123(3) per unit cell, ...

Exchange of a Tetrapositive Cation into a Zeolite and a New Inorganic Scintillator. I. Crystal Structures and Scintillation Properties of Anhydrous Zr1.7Tl5.4Cl1.7–LTA and Zr2.1Tl1.6Cl3.0–LTA

A new inorganic scintillator has been prepared by the assembly of thallium, zirconium, and chloride ions in a zeolite. Also, for the first time, a 4+ cation has been exchanged directly into a zeolite. From |Na12(H2O)x|[Si12Al12O48]-A (zeolite LTA), |Zr1.7Tl5.4Cl1.7|[Si13.5Al10.5O48]-A and |Zr2.1Tl1.6Cl3.0|[Si17.4Al6.6O48]-A were prepared by the thallous ion exchange (TIE) method: fully dehydrated Tl12-A was treated with ZrCl4 (g, 3.7 × 103 Pa) at 553 and 623 K, respectively. Their crystal structures were determined by single-crystal crystallography using synchrotron X-radiation and their compositions were partially confirmed by SEM-EDX analyses. Their structures were refined in the space group Pm3m (a = 12.215(1) and 11.945(1) A) with all unique data to the final error indices R1 = 0.047 and 0.075 for the 680 and 380 reflections for which Fo > 4σ(Fo), respectively. Extraframework Zr4+ and Zr2+ ions had replaced some of the Tl+ ions in Tl12-A. Some Zr4+ ions are 4-coordinate with three bonds to framework o...

Using the Thallous Ion Exchange Method to Exchange Tin into High Alumina Zeolites. 1. Crystal Structure of |Sn2+5.3Sn4+0.8Cl–1.8|[Si12Al12O48]-LTA

Sn2+ and Sn4+ ions have replaced all of the Tl+ ions in the zeolite Tl12-A (|Tl12|[Si12Al12O48]-LTA) by thallous ion exchange (TIE), a vapor phase ion exchange method: SnCl2(g) was allowed to react with Tl12-A under anhydrous conditions at 723 K for 48 h. The tin content of the product, |Sn2+5.3Sn4+0.8Cl–1.8|[Si12Al12O48]-LTA, is 32.6 wt %, much higher than previously reported for any zeolite. Its structure was determined by single-crystal crystallography at 294 K using synchrotron X-radiation (Pm3m, a = 12.075(1) A, R1 = 0.069, R2 = 0.224), and its composition was confirmed by scanning electron microscopy energy-dispersive X-ray analysis. Sn2+ is found at four crystallographic positions, Sn4+ at two, and Cl– at two. Among the 5.3 Sn2+ ions per unit cell, 2.7 (3-coordinate) lie opposite 6-rings in large cavities, 0.3 (4-coordinate) are opposite 6-rings in sodalite cavities, 1.5 are in 8-rings, and 0.7 approach a framework oxygen atom and two chloride ions in a trigonal planar manner. Among the 0.8 Sn4+ i...

First Successful Application of the Thallous Ion Exchange (TIE) Method. Preparation of Fully Indium-Exchanged Zeolite Y (FAU, Si/Al = 1.69)

Fully indium-exchanged zeolite Y, |In+62.6(In57+)1.2|[Si121Al71O384], was prepared by thallous ion exchange (TIE), a vapor phase ion exchange method. InCl(g, 510 Pa) was allowed to react with a single crystal of Tl71–Y under anhydrous conditions at 623 K. A second crystal prepared as above was washed with deionized water and redehydrated to give |In+39.7 (In57+)4.5|[Si121Al71O384]. The structures of fully dehydrated Tl71–Y and these two forms of In–Y were determined by single-crystal crystallography using synchrotron X-radiation. Then the two In–Y crystals were subjected to scanning electron microscopy energy-dispersive X-ray (SEM-EDX) analysis. Both methods indicated that no Tl remained in the In–Y crystals. The additional steps of washing and redehydration caused some of the In+ ions in the first In–Y crystal to disproportionate to give additional In57+ clusters in the sodalite cavities and In0 atoms on the crystal surface. Most of the In+ ions in both forms of In–Y are easily accessible to guest molecu...

Introducing copper ions into zeolite Y by the thallous ion exchange method: single crystal structure of |Cu21.6Tl39.2|[Si121Al71O384]–FAU

The thallous ion exchange (TIE) method was used for the first time in an attempt to introduce copper ions into zeolite Y (FAU, Si/Al = 1.69). |Cu 10.9 + Cu 10.7 2+ Tl 39.2 + |[Si121Al71O384]–FAU was prepared by reacting fully dehydrated and fully Tl+-exchanged zeolite Y (Tl71–Y) with CuCl2(g) and its decomposition products CuCl(g) and Cl2(g) at 673 K under anhydrous conditions. Its structure was determined using single-crystal crystallography with synchrotron X-radiation and was refined in the space group $${Fd}\bar{3}$$ m (a = 24.769(1) A) with all 903 unique data; the final error index, R 1 = 0.075, was calculated using only the 858 reflections with F o > 4σ(F o). About 45 % of the Tl+ ions were replaced by 21.6 copper ions per unit cell at the following sites (distances to nearest framework oxygen atoms are given): 10.7 Cu2+ at site I′ in the sodalite cavity opposite double 6-rings (Cu2+–O = 2.093(9) A), 3.5 Cu+ at site II opposite single 6-rings in the supercage (Cu+–O = 2.24(3) A), and 7.4 Cu+ at site III near 12-rings in the supercage (Cu+–O = 2.45(7) A). All Cu+ ions are in supercages where they are easily accessible to guest molecules. The remaining ca. 39 Tl+ ions per unit cell occupy three distinct positions: 12 are at a second site I′ (Tl+–O = 2.571(9) A), 23 are at a second site II (Tl+–O = 2.732(10) A), and 4 are at site III′ (Tl+–O = 2.871(16) A) near triple 4-rings in the supercages.

Sorption of thallous ion from acidic aqueous solutions onto ETS-10 titanosilicate

The sorption of the thallous ion from aqueous acidic solution (pH = 1.5) onto as-synthesized and modified ETS-10 titanosilicates was studied by using an isotope dilution method and a batch-mode technique. The present results show that the thallium(I) sorption was effective onto all three considered materials and is enhanced by the porosity and acidity modification of the ETS-10 titanosilicate. The best uptake performance was achieved by the meso-ETS-10. This behavior is explained based on the newly created additional mesoporous system and enriching the external surface with silanol groups. Also, the presence of phosphorus enhanced the inherent porosity allowing thus better internal diffusion properties of crystalline material. However, the chemically modified surface seems to have a negative contribution to the kinetic uptake of thallous ion as shown by the positive value of the activation energy E a, in comparison with the processes more favorable energetically for ETS-10 and meso-ETS-10 materials.

The incomplete dissociation of thallous hydroxide

The thallous ion and silver ions are unique among univalent cations in forming fairly strong complexes with univalent anions. A review of previous evidence (involving measurements of solubilities, conductivities and reaction kinetics) indicates that thallous hydroxide is incompletely dissociated, having a thermodynamic dissociation constant of about 0.15. New data are reported on the effect of thallous ions on the velocity of the fast reaction between nitroethane and hydroxyl ions. These lead to a similar value for the dissociation constant if it is assumed that the species TIOH does not react. Measurements have also been made of the ultra-violet absorption of solutions containing thallous and hydroxide ions. The results show clearly the presence of two distinct absorbing species, and although it is not possible to derive unambiguously a dissociation constant for TIOH, the data are consistent with the value given above. The nature of the binding in TIOH is discussed in the light of the above findings.

A General Method for the Ion Exchange of Zeolites Utilizing the Volatility of Thallous Compounds as Leaving Products

A new method of ion exchange entitled “thallous ion exchange” (TIE) is proposed without experimental confirmation. First, a zeolite or other porous solid is fully ion exchanged with Tl+ from aqueous solution and fully dehydrated. It is then exposed to the anhydrous vapor of a halide MXn where Mn+ is the incoming cation. The volatile product TlX(g) is easily removed, leaving behind, when successful, the fully cation exchanged material with no other content. During the Mn+ exchange step, the zeolite is in contact only with gases and its container. The Tl+ exchanged zeolite may also be used in solid state ion exchange to yield TlX(g). Although Tl+ is best for this, some other metal cations may be used. Although the halides offer much versatility with relative safety, oxides and organometallic compounds may be used because the Tl2O and R3Tl products are also volatile.

Photoinduced Electron Transfer via Nonbuttressed Metal−Metal Bonds. The Photochemical Study of Binuclear Complexes with Platinum−Thallium Bonds

The photochemistry of binuclear metal-metal bonded complexes [(NC) 5Pt-Tl(solv) x ] (solv is water or dimethylsulfoxide) has been studied in aqueous and dimethylsulfoxide solutions. Both stationary and nanosecond laser flash photolysis have been carried out on the species. The metal-metal bonded complexes have been photolyzed by irradiation into the corresponding intense MMCT absorption bands. Photoexcitation results in the cleavage of the platinum-thallium bond and the formation of a solvated thallous ion and a cyano complex of platinum(IV), [Pt(CN) 5(solv)] (-), in both cases. The species have been characterized by multinuclear NMR and optical spectroscopy. The products of the photoreaction indicate a complementary two-electron transfer occurring between platinum and thallium ions in the binuclear Pt-Tl species. Quantum yield values for the photodecomposition of the species have been determined. The intermediates of the photoinduced metal-to-metal electron transfer have been detected and characterized by optical spectroscopy. The kinetics of transient formation and decomposition have been studied, and mechanisms of the photoactivated redox reaction have been suggested.

Probing interactions from solvent‐exchangeable protons and monovalent cations with the 1,2‐propanediol‐1‐yl radical intermediate in the reaction of dioldehydrase

The reaction of adenosylcobalamin-dependent dioldehydrase with 1,2-propanediol gives rise to a radical intermediate observable by EPR spectroscopy. This reaction requires a monovalent cation such as potassium ion. The radical signal arises from the formation of a radical pair comprised of the Co(II) of cob(II)alamin and a substrate-related radical generated upon hydrogen abstraction by the 5'-deoxyadenosyl radical. The high-field asymmetric doublet arising from the organic radical has allowed investigation of its composition and environment through the use of EPR spectroscopic techniques. To characterize the protonation state of the oxygen substituents in the radical intermediate, X-band EPR spectroscopy was performed in the presence of D(2)O and compared to the spectrum in H(2)O. Results indicate that the unpaired electron of the steady-state radical couples to a proton on the C(1) hydroxyl group. Other spectroscopic experiments were performed, using either potassium or thallous ion as the activating monovalent cation, in an attempt to exploit the magnetic nature of the (205,203)Tl nucleus to identify any intimate interaction of the radical intermediate with the activating cation. The radical intermediate in complex with dioldehydrase, cob(II)alamin and one of the activating monovalent cations was observed using EPR, ENDOR, and ESEEM spectroscopy. The spectroscopic evidence did not implicate a direct coordination of the activating cation and the substrate derived radical intermediate.

201Tl](III)-bleomycin for tumor imaging

Summary Due to interesting physical properties and wide availability of thallium-201 as a SPECT radionuclide, the idea of incorporation of this nuclide into biologically active compounds was targeted. Thallium-201 (T 1/2 = 3.04 d) in Tl+ form was converted to Tl3+ cation in presence of O3 in 6 M HCl controlled by RTLC/gel electrophoresis methods. The final evaporated activity was reacted with bleomycin in normal saline to yield [201Tl]BLM at room temperature after 0.5 h (radiochemical yield > 99%) followed by HPLC analysis. The studies showed that thallic ion is mostly incorporated into bleomycin A2 while other species in the pharmaceutical sample almost remain unlabeled. Radiochemical purity of more than 99% was obtained using RTLC, HPLC with specific activity of about 7 Ci/mmol. The stability of the tracer was checked in the final product in presence of human serum at 37 °C up to 3 d. The tracer accumulated in tumors of fibrosarcoma-bearing mice after 72 h.

Suicide Inactivation of Dioldehydrase by 2‐Chloroacetaldehyde: Formation of the ‘cis‐Ethanesemidione’ Radical, and the Role of a Monovalent Cation

AbstractDioldehydrase is an adenosylcobalamin‐dependent enzyme that catalyzes the dehydration of (R)‐ or (S)‐propane‐1,2‐diol to propanal. The reaction proceeds by a radical mechanism initiated by the homolytic scission of the covalent CoC(5′) bond in the coenzyme to form cob(II)alamin and the 5‐deoxyadenosyl radical as transient intermediates. Dioldehydrase is subject to ‘suicide inactivation’ by substrate/product analogs. Inactivation by 2‐chloroacetaldehyde converts the inactivator into the ‘cis‐ethanesemidione’ radical. A mechanism for this process includes reaction of chloroacetaldehyde in the reverse of the normal catalytic process to a rearranged radical that eliminates HCl. K+ and other monovalent cations of similar size, including Tl+, are required for dioldehydrase activity and for suicide inactivation by glycolaldehyde or 2‐chloroacetaldehyde. A K+ ion is bound to propane‐1,2‐diol in dioldehydrase. Both EPR and pulsed‐EPR experiments show that the magnetic nuclei of thallous ions (203Tl+, 205Tl+) do not interact with the unpaired electron in the cis‐ethanesemidione radical at the active site of dioldehydrase. Pulsed‐EPR experiments implicate a 14NH group, possibly of His143, interacting with the radical at the active site.

Synthesis and structural characterization of new defect pyrochlore type A xLn ySb 2O 6+ z antimoniates (0< x, y, z

New cubic defect pyrochlore type A x Ln y Sb 2O 6+ z antimoniates (0< x, y, z<1; A=Rb, Cs, Tl; Ln=Eu, Gd, and Y) (space group Fd3 m) were prepared by calcination in air at 650 °C of compositions obtained by a coprecipitation method. Their crystal structures were refined by the Rietveld procedure and further confirmed by X-ray absorption spectroscopy (EXAFS) experiments. Refinements of the X-ray powder diffraction data show a partial and statistical occupation of the 8b site by alkaline or thallous ions and oxygen and lead to values close to 0.33 for the only refinable positional x parameter of the 48f oxygenated site.

Impedance study of thallous ion movement through gramicidin–dioleoylphosphatidylcholine self-assembled monolayers supported on mercury electrodes: the C–(C)–CE mechanism

A new mechanism (the C–(C)–CE mechanism) is proposed for Tl + reduction and Tl–amalgam oxidation on gramicidin-modified dioleoylphosphatidylcholine (DOPC) mercury and Tl–amalgam electrodes. The faradaic impedance equations are derived, and applied to the experimental results obtained in 0.1 M KCl solutions at a high gramicidin concentration. The mechanism includes two consecutive heterogeneous chemical steps with an intermediate, which decomposes in a parallel homogeneous chemical step. The two heterogeneous chemical steps are assumed to mimic the interaction of the ion with the channel mouth and the further translocation across the channel, respectively. The results fit the mechanism well, and the analysis provides the equilibrium constant for the first chemical step and the forward rate constant for the translocation step. The latter was found to depend on the drop in potential across the interface, with a transfer coefficient α=0.2, in both the reduction and the oxidation experiments. However, the translocation step standard rate constant provided by the oxidation experiment is lower than that by the reduction experiment, indicating some asymmetry in the half-channel behaviour.

Pore formation by 6-ketocholestanol in phospholipid monolayers and its interpretation by a general nucleation-and-growth model accounting for the sigmoidal shape of voltage-clamp curves of ion channels.

6-Ketocholestanol (KC), a steroid that differs from cholesterol mainly by the presence of a carbonyl group, forms pores inside a dioleoylphosphatidylcholine monolayer self-assembled on mercury by a mechanism similar to that of channel-forming peptides and proteins. The potential steps responsible for pore formation by KC molecules give rise to potentiostatic charge vs time curves whose sigmoidal shape and potential dependence can be quantitatively interpreted on the basis of a mechanism of nucleation and growth of KC clusters. Pore formation by KC allows the penetration of thallous ions across the otherwise impermeable phosphatidylcholine monolayer, while pore disruption taking place at more negative potentials causes a drop in thallous ion permeation. Pore disruption is also accounted for by a mechanism of nucleation and growth of holes inside the KC clusters. The kinetic model of nucleation and growth is general, and accounts quantitatively for the sigmoidal shape and potential dependence of the classical Hodgkin-Huxley voltage-clamp curves of potassium channels in squid giant axon,(1) using a minimum number of free parameters.

Resolving independent ion and ion displacement transport mechanisms in ion channels

Univalent metal ion fluxes in gramicidin channels in bilayer membranes produce linear current–voltage plots. Both independent ion models with first-order rate constants or ion–ion displacement models with pseudo-first-order rate constants reproduce the linear current–voltage behavior. To differentiate the mechanisms, the anomalous behavior of the system at low thallous ion mole fractions is studied using a potential ramp protocol. Under these conditions, the current–voltage plots separate into three linear segments with a low conductance segment at lower potentials and parallel outer segments with higher conductance whose voltage axis intercepts are displaced from zero potential. This displaced threshold potential varies with thallous ion mole fraction but has a constant electrochemical potential for all mole fractions. The current–voltage plots and their properties suggest a low conductance mechanism where thallous ion exclusion from the channel obeys Boltzmann statistics in the electrochemical potential. The higher conductance outer segments for electrochemical potentials that exceed the threshold obey a multi-ion displacement.

Thallous Ion Movements through Gramicidin Channels Incorporated in Lipid Monolayers Supported by Mercury

The potential independent limiting flux of hydrated Tl + ions through gramicidin (GR) channels incorporated in phospholipid monolayers self assembled on a hanging mercury-drop electrode is shown to be controlled both by diffusion and by a dehydration step. Conversely, the potential independent limiting flux of dehydrated Tl + ions stemming from Tl amalgam eletrooxidation is exclusively controlled by diffusion of thallium atoms within the amalgam. Modulating the charge on the polar heads of dioleoylphosphatidylserine (DOPS) by changing pH affects the limiting flux of hydrated Tl + ions to a notable extent, primarily by electrostatic interactions. The dipole potential of DOPS and dioleoylphosphatidylcholine (DOPC), positive toward the hydrocarbon tails, does not hinder the translocation step of Tl + ions to such an extent as to make it rate limiting. Consequently, incorporation in the lipid monolayer of phloretin, which decreases such a positive dipole potential, does not affect the kinetics of Tl + flux through GR channels. In contrast, the increase in the positive dipole potential produced by the incorporation of ketocholestanol causes the translocation step to contribute to the rate of the overall process. A model providing a quantitative interpretation of the kinetics of diffusion, dehydration–hydration, translocation, and charge transfer of the Tl +/Tl 0(Hg) couple through GC channels incorporated in mercury-supported phospholipid monolayers is provided. A cut-off disk model yielding the profile of the local electrostatic potential created by an array of oriented dipoles located in the lipid monolayer along the axis of a cylindrical ion channel is developed.