Adsorption of Co2+, Ni2+, Cu2+ and Zn2+ from 0.5 M NaCl and major ion sea water on a mixture of delta-MnO2 and amorphous FeOOH

The pH(pzc) values of several mechanical mixtures of amorphous hydrous oxides of iron (amorphous FeOOH) and manganese (delta-MnO2) have been determined using the solid addition method. While the pH(pzc) of delta-MnO2 remains almost unchanged, the corresponding value for amorphous FeOOH tends to increase with increased proportion of delta-MnO2 in the mixtures. The adsorption behavior of Co2+, Ni2+, Cu2+, and Zn2+ with respect to pH on a mechanical mixture of 70% delta-MnO2 and 30% amorphous FeOOH from 0.5 M NaCl and major ion sea water has been studied. Since delta-MnO2 is much more active adsorbent than amorphous FeOOH at pH below 6.5, the adsorption data on mixture have not only been normalized with respect to the mass of delta-MnO2 in the mixture, but also compared with adsorption data on delta-MnO2 alone. It is interesting to note that though each trace metal behaves in a different way from the other especially with respect to the nature of electrolyte medium, it is generally observed that the adsorption on the mixed oxide system is higher than that on delta-MnO2 alone under similar condition. It is also observed that adsorption in major ion sea water at a particular pH value is lower than in 0.5 M NaCl solution.     

Adsorption of Co2+, Ni2+, Cu2+, and Zn2+ onto amorphous hydrous manganese dioxide from simple (1-1) electrolyte solutions

The adsorption of Co2+, Ni2+, Cu2+, and Zn2+ onto amorphous hydrous manganese dioxide (delta-MnO2) has been studied using two methods, viz., isotherms at constant pH in the presence of buffer solution and pH variation in the absence of buffer solution from a fixed metal ion concentration. While the adsorption isotherm experiments were carried out in 0.5 M NaCl only, pH variation or batch titration experiments were carried out in 0.5 M NaCl, 0.01 M NaCl, and 0.01 M KNO3 solutions. The complex nature of adsorption isotherms at constant pH values indicates that adsorption of all the cations is non-Langmuirian (Freundlich) and takes place on the highly heterogeneous oxide surface with different binding energies. The proton stoichiometry derived from isotherms at two close pH values varies between 0.3 and 0.8. The variation of fractional adsorption with pH indicates that the background electrolyte solution influences the adsorption of cations through either metal-like or ligand-like complexes with Cl-, the former showing a low adsorption tendency. The proton stoichiometry values derived from the Kurbatov-type plot varies not only with the electrolyte solution but also with the adsorbate/adsorbent ratio. The variation of fractional adsorption with pH can be modeled either with the formation of the SOM+ type or with a combination of SOM+ and SOMOH type complexes, depending upon the cation and electrolyte medium. The equilibrium constants obtained from Kurbatov-type plots are found to be most suitable in these model calculations. Adsorption calculated on the basis of ternary surface metal-chlorocomplex formation exhibits very low values.     

Dilatometric study of the adsorption of heavy-metal cations on goethite

The specific volumes of adsorption of Cd, Co, Cu, Ni, Pb, and Zn on goethite determined by means of the dilatometric method are 21, 32, 32, 31, 31, and 42 cm3/mol, respectively, and are independent of pH. The effect of NaCl (up to 0.5 mol dm(-3)) on the specific volume of adsorption is rather insignificant. The specific volume of precipitation of corresponding hydroxides (determined experimentally and calculated) is about 60 cm3/mol. Apparently, the adsorbed heavy-metal cations lose half of their hydration water. The adsorption constant decreases as the pressure increases, and the effect becomes significant at pressures of > 10(7) Pa, i.e., more than 1 km of water column.     

Al2O3自电解质溶液中吸附CrO4^2^-的特性研究

本文特别延长了pH范围(2-10),详细研究pH、温度、外加正负离子对CrO4^2^-吸附量的影响,说明这种吸附主要是以离子交换方式进行的,并认为表面活性点是产生这类吸附的重要原因.     

Effect of relative humidity on OH uptake by surfaces of atmospheric importance

An experimental study of the dependence of the OH uptake coefficient gamma OH over a relative humidity of 0-48% was carried out at 100 Torr and room temperature, using a differential bead-filled flow tube coupled to a high-pressure chemical ionization mass spectrometer. Various organic (paraffin wax, pyrene, glutaric acid, and soot) and inorganic (NaCl, KCl, MgCl2, CaCl2, Na2SO4, and sea salt) surfaces served as proxies for tropospheric aerosols. A virtual cylindrical flow tube approximation and a surface coating dilution technique were successfully employed in the study, which included measurements of high radical uptake with an initial probability of near unity. For inorganic salts, the effect of water vapor, enhancement or inhibition of gamma OH, was found to be dependent on the blocking of anions and changes in surface pH. Although OH uptake by NaCl, the major component of sea-salt aerosols, is weakly dependent on water vapor, it is enhanced by a factor of approximately 2 for MgCl2 and determines the net relative humidity dependence of the radical uptake on sea salt, which is enhanced by a factor of approximately 4. For the organic surfaces studied, the enhancement effect of a factor 4 was also observed only for a hydrophilic organic surface, namely, glutaric acid. Results of the uptake studies suggest that the effect of relative humidity is important and should be accounted for in atmospheric modeling of tropospheric aerosol chemistry.     

Simultaneous determination of Cd, Pb, Cu, Sb, Bi, Se, Zn, Mn, Ni, Co and Fe in water samples by differential pulse stripping voltammetry at a hanging mercury drop electrode

A highly sensitive and selective voltammetric procedure is described for the simultaneous determination of eleven elements (Cd, Pb, Cu, Sb, Bi, Se, Zn, Mn, Ni, Co and Fe) in water samples. Firstly, differential pulse anodic stripping voltammetry (DPASV) with a hanging mercury drop electrode (HMDE) is used for the direct simultaneous determination of Cd, Pb, Cu, Sb and Bi in 0.1 M HCI solution (pH = 1) containing 2 M NaCl. Then, differential pulse cathodic stripping voltammetry (DPCSV) is used for the determination of Se in the same solution. Zn is subsequently determined by DPASV after raising the pH of the same solution to pH 4. Next, the pH of the medium is raised to pH 8.5 by adding NH3/NH4Cl buffer solution for the determination of Mn by DPASV. Ni and Co are determined in the same solution by differential pulse adsorptive stripping voltammetry (DPAdSV) after adding DMG (1 x 10(-4) M). Finally, 1 x 10(-5) M 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) is added to the solution for the determination of Fe by DPAdSV. The optimal conditions are described. Relative standard deviations and relative errors are calculated for the eleven elements at three different concentration levels. The lower detection limits for the investigated elements range from 1.11 x 10(-10) to 1.05 x 10(-9)M, depending on the element determined. The proposed analysis scheme was applied for the determination of these eleven elements in some ground water samples.     

Dithlzone extraction and flame atomic absorption spectrometry for the determination of cadmium,zinc, lead,copper, nickel,cobalt and silver in sea water and biological tissues

The method previously described for the determination of Cd, Zn, Cu, Ni and Co in sediments has been adapted for the determination of these metals, and lead and silver in sea water and biological tissues. For sea water the only treatment preceding extraction is pH adjustment; biological tissues are digested in nitric and perchloric acids and the residue taken up in dilute hydrochloric acid prior to pH adjustment and extraction. The method is sufficiently sensitive to allow Cd, Zn, Cu and Ni to be determined in all sea waters, Co and Ag in coastal waters, but Pb only in polluted water.     

Novel 3D, 2D, and 0D first-row coordination compounds with 4,4'-bipyridine-N,N'-dioxide incorporating sulfur-containing anions

The reaction of M(S2O6) (M = Cu(II), Ni(II), and Co(II)) with 4,4'-bipyridine-N,N'-dioxide (bpdo) results in the formation of novel 3D, 2D, and mononuclear complexes. Complex 1, {[Cu(H2O)(bpdo)2](S2O6)(H2O)}n, is a 2-D wavelike polymer with the Cu(II) ion located on a 2-fold axis and having a distorted square-pyramidal coordination sphere. With Co(II) and Ni(II), 3-D complexes, {[M(bpdo)3](S2O6)(C2H5OH)7}n [M = Co(II) (2), Ni(II) (3)], were obtained. The metal atoms are situated on centers of symmetry and have octahedral environments coordinated to six bpdo molecules. The same reaction in aqueous solution with a metal/ligand ratio of 1:1 results in the formation of mononuclear complexes, {[M(bpdo)(H2O)5](SO4)(H2O)2} [M = Co(II) (4), Ni(II) (5)], accompanied by the decomposition of the dithionate anions S2O6(2-) to sulfate anions SO4(2-).     

Cloud Point Extraction Simultaneous Spectrophotometric Determination of Zn(II), Co(II) and Ni(II) in Water and Urine Samples by 1-(2-Pyridylazo)2-Naphthol Using Partial Least Squares Regression

A cloud-point extraction (CPE) process using the nonionic surfactant Triton X-114 to simultaneous extraction and spectrophotometric determination of Zn(II), Co(II) and Ni(II) from aqueous solution using partial least squares (PLS) regression is investigated. The method is based on the color reaction of these cations with 1-(2-pyridylazo)2-naphthol and subsequent micelle-mediated extraction of products. The optimum extraction and reaction conditions such as pH, reagents concentration and effect of time have been studied. Linearity was obeyed in the range 2–150, 5–250 and 2–150 ng mL⁻¹ of Zn(II), Co(II) and Ni(II) respectively. The relative standard error (RSE) for the simultaneous determination of 15 test samples of different concentrations of Zn(II), Co(II) and Ni(II) was 4.38%;, 1.18% and 2.42%, respectively. The total relative standard error (RSE_t) for applying the PLS method to 15 synthetic samples in the linear ranges of these metals was 2.36%. The interference effect of some anions and cations was also tested. The method was applied to the simultaneous determination of Zn(II), Co(II) and Ni(II) in water and human urine samples.     

Synthesis, crystal structure, and solution stability of Keggin-type heteropolytungstates (NH4)6NiII0.5[alpha-FeIIIO4W11O30NiIIO5(OH2)].nH2O, (NH4)7Zn0.5[alpha-ZnO4W11O30ZnO5(OH2)].nH2O, and (NH4)7NiII0.5[alpha-ZnO4W11O30NiIIO5(OH2)].nH2O (n approximately 18)

Reaction of acidified (pH approximately 7) sodium tungstate solutions with transition metal cations (Fe(3+), Ni(2+), Zn(2+), Co(2+)) leads to the formation of transition-metal-disubstituted Keggin-type heteropolytungstates with 3d-metal ions distributed over three different positions. A detailed investigation of the synthesis conditions confirmed that the complexes could equally be obtained using aqueous solutions of either Na(2)WO(4).2H(2)O (sodium monotungstate) at pH approximately 7, Na(6)[W(7)O(24)]. approximately 14H(2)O (sodium paratungstate A), or Na(10)[H(2)W(12)O(42)].27H(2)O (sodium paratungstate B) as starting materials. Three complexes, (NH(4))(6)Ni(II)(0.5)[alpha-Fe(III)O(4)W(11)O(30)Ni(II)O(5)(OH(2))].18H(2)O, (NH(4))(7)Zn(0.5)[alpha-ZnO(4)W(11)O(30) ZnO(5)(OH(2))].18H(2)O, and (NH(4))(7)Ni(II)(0.5)[alpha-ZnO(4)W(11)O(30)Ni(II)O(5)(OH(2))].18H(2)O were isolated in crystalline form. X-ray single-crystal structure analysis revealed that the solid-state structures of the three compounds consist of four main structural fragments, namely [MO(4)W(11)O(30)M'O(5)(OH(2))](n-) (Keggin-type, alpha-isomer) heteropolytungstates, hexaquo metal cations, [M'(OH(2))(6)](2+), ammonium-water cluster ions, [(NH(4)(+))(8)(OH(2))(12)], and additional ammonium cations and water molecules. The 3d metals occupy the central (tetrahedral, M) and the peripheral (octahedral, M') positions of the Keggin anion, as well as cationic sites (M') outside of the polyoxotungstate framework. UV-vis spectroscopy, solution ((1)H, (183)W) and solid-state ((1)H) NMR, and also chemical analysis data provided evidence that the 3d-metal-disubstituted Keggin anions do not exist in solution but are being formed only during the crystallization process. Investigations in the solid state and in solution were completed by ESR, IR, and Raman measurements.     

Preparation, characterization and metal sorption studies of a Chrome-Azurol-S-loaded anion-exchange resin

Chrome Azurol S (CS) was mobilized on an strongly basic anion-exchange resin (Dowex 2 x 4, in Cl(-) form) by batch equilibration. The modified resin was stable in acetate buffer solution and in 0.1 M HCl and H(2)SO(4), but it was readily degraded with 2-6 M HCl and HNO(3). Retention of Ba(II), Sr(II), Ca(II), Mg(II), Al(III), Cr(III), Zn(II), Fe(III), Ti(IV), Mn(II), Co(II), Ni(II), Cu(II), Cd(II) and Pb(II) was studied using the batch equilibration method. The uptake and recovery yields were determined by using inductively-coupled plasma atomic emission spectroscopy (for Mg, Al, Cr, Ti, Fe, Mn, Ni, Zn, Cu, Cd and Pb) and atomic absorption spectrophotometry (for Ba, Sr, Ca and Co). The optimum pH value was established for performing a selective separation of Al(III) from the other metal ions. The sorption capacities of the CS-loaded resing for Al(III), Cr(III), Mg(II) (at pH 6), Fe(III) (at pH 5) and Ti(IV) (at pH 4) were 14, 2.9, 0.3, 3 and 3.9 mumoles g(-1) respectively. On this basis a method for separating Al(III) from other cations was established.     

Adsorption, separation, and thermochemical data on the herbicide picloram anchored on silica gel and its cation interaction behavior

The herbicide 4-amino-3,5,6-trichloropicolinic acid (picloram), chemically anchored on silica gel surface (SiPi), has been used for divalent cation M(2+) (Cu, Ni, Zn, and Cd) adsorption from aqueous solutions at room temperature. The series of adsorption isotherms were adjusted to a modified Langmuir equation from data obtained by suspending the solid with MCl(2) solutions, which gave the maximum number of moles adsorbed as 9.27, 7.54, 5.12, and 1.54 x 10(-4) molg(-1) for Cu, Ni, Zn, and Cd, respectively. The minimum cation retention capacity from aqueous solution was observed at pH 1, increasing up to pH 4, and was maintained constant at pH 5 for all cations. The maximum retention capacity followed the sequence Cu>Ni>Zn>Cd. SiPi-M (Cu, Ni) interactions presented endothermic enthalpic values, which contrasted with exothermic values for SiPi-M (Zn, Cd) interactions. The anchored herbicide was also used to separate the cations when loaded in a column. Their resolutions were determined as the ability of this surface to separate cations, to give Rs(Cd-Zn)=2.33, Rs(Cd-Ni)=3.16, Rs(Cd-Cu)=7.21, Rs(Zn-Ni)=1.31, Rs(Zn-Cu)=2.55, and Rs(Ni-Cu)=0.72.     

Amberlite XAD-7 impregnated with Xylenol Orange: a chelating collector for preconcentration of Cd(II), Co(II), Cu(II), Ni(II), Zn(II) and Fe(III) ions prior to their determination by flame AAS

A new chelating resin, Xylenol Orange coated Amberlite XAD-7, was prepared and used for preconcentration of Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) prior to their determination by flame atomic absorption spectrophotometry. The optimum pH values for quantitative sorption of Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) are 4.5-5.0, 4.5, 4.0-5.0, 4.0, 5.0 and 5.0-7.0, respectively, and their desorptions by 2 mol L(-1) HCl are instantaneous. The sorption capacity of the resin has been found to be 2.0, 2.6, 1.6, 1.6, 2.6 and 1.8 mg g(-1) of resin for Cd, Co, Cu, Fe, Ni and Zn, respectively. The tolerance limits of electrolytes, NaCl, NaF, NaI, NaNO3, Na2SO4 and of cations, Mg2+ and Ca2+ in the sorption of the six metal ions are reported. The preconcentration factor was between 50 and 200. The t1/2 values for sorption are found to be 5.3, 2.9, 3.2, 3.3, 2.5 and 2.6 min for the six metals, respectively. The recoveries are between 96.0 and 100.0% for the different metals at preconcentration limits between 10 to 40 ng mL(-1). The preconcentration method has been applied to determine the six metal ions in river water samples after destroying the organic matter (if present in very large amount) with concentrated nitric acid (RSD < or = 8%, except for Cd for which it is upto 12.6%) and cobalt content of vitamin tablets with RSD of approximately 3.0%.     

具有氢键假想孔道结构的[M(en)3][GeF6](M=Ni,Co)的合成与表征

描述了两个具有管状氢键假想孔道结构的化合物[Ni(en)3][GeF6][JLG-1(Ni)]和[Co(en)3].[GeF6][JLG-1(Co)].在这两个结构中,[GeF6]2-阴离子与手性金属配合物阳离子[M(en)3]2+(M=Ni,Co)通过F…N之间复杂的弱氢键相互作用,在沿着63螺旋轴方向形成六方蜂窝状排布的管状氢键假想孔道.结构研究发现,配对的[GeF6]2阴离子和手性[M(en)3]2+阳离子同属于D3点群,这是JLG-1(Ni)和JLG-1(Co)形成管状氢键假想孔道的关键.这一研究成果对设计合成氢键假想孔道体系具有一定的指导意义.     

Methode d'elution selective pour l'extraction des metaux lourds de l'eau de mer sur resine chelatante: A selective method of elution for the extraction of heavy metals from sea waters on a chelating resin

A selective method of elution for the extraction of heavy metals from sea waters on a chelating resin.The extraction of heavy metals in sea water with Chelex 100 prior to their determination by atomic absorption spectrometry (a.a.s.) with electrothermal atomization is discussed. Maximum retention of heavy metals is not obtained with the resin in the H⁺ form, because it is gradually transformed in contact with sea water by the fixation of alkali and alkaline-earth cations which are eluted simultaneously with the heavy metals and interfere during a.a.s. The separation of heavy metals is quantitative on Chelex 100 in the Ca²⁺ form; treatment with dilute acetic acid (1 + 99) eliminates the alkali and alkaline-earth metals fixed on the resin before elution or the heavy metals. Elution with 1 M nitric acid gives simultaneous and quantitative recovery of Cu, Pb, Ni, Zn, Cd and Co; intermediate elution with 0.01 M nitric acid isolates Zn, Cd and Co from Cu and Pb, which are subsequently eluted with 1 M nitric acid.     

Interaction of Molybdenum(VI) Oxyanions with +2 Metal Cations

The association of molybdenum(VI) oxyanions with metal cations was investigated in solutions of low ionic strength, such as those prevailing in most natural waters. Potentiometric titrations were carried out for the systems containing molybdenum(VI) anions and divalent metal cations (M = Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg and Pb). This selection includes the major cations and some other cations of high environmental relevance. The interaction of iron(III) with Mo(VI) anions was also studied. At neutral and basic pH values and for those systems where the solubility of the molybdate salt is high enough, ionic species pairs such as [M(MoO₄)] predominate. At acidic pH values, [M(HMoO₄)]⁺ and [M(Mo₇O₂₄)]^4– are formed, the latter species are only relevant for total molybdenum concentrations higher than 1 mmol·L^?1. These results provide the basis for molybdenum speciation in natural aquatic systems, on which the environmental fate, bioavailability and toxicity of the element depend.     

Adsorption of Co(II), Ni(II), Cu(II), and Zn(II) on hexagonal templated zirconia obtained thorough a sol-gel process: the effects of nanostructure on adsorption features

Using zirconium tetrabutoxide, diaminedecane, and diamineoctane as precursors, a templated hexagonal zirconia matrix is synthesized and characterized by X-ray diffractometry and scanning electron microscopy. The adsorption capacity of such a matrix toward Co(II), Ni(II), Cu(II), and Zn(II) from aqueous solutions is studied. The adsorption affinity of the synthesized hexagonal templated zirconia toward the cations is Cu(II)>Zn(II) >Ni(II)>Co(II). It is also verified that the adsorption of the cations follows a Langmuir and not a Freundlich isotherm. All obtained isotherms are of type I, according to the IUPAC classification. The observed adsorption affinity sequence can be explained by taking into account the velocity constant for the substitution of water molecules into the cation coordination spheres, as well as the Irving-Williams series.     

Metal Cyanide Ions Mx(CN)y]+,- in the gas phase: M = Fe,Co, Ni,Zn, Cd,Hg, Fe + Ag,Co + Ag

The generation of metal cyanide ions in the gas phase by laser ablation of M(CN)(2) (M = Co, Ni, Zn, Cd, Hg), Fe(III)[Fe(III)(CN)(6)] x xH(2)O, Ag(3)[M(CN)(6)] (M = Fe, Co), and Ag(2)[Fe(CN)(5)(NO)] has been investigated using Fourier transform ion cyclotron resonance mass spectrometry. Irradiation of Zn(CN)(2) and Cd(CN)(2) produced extensive series of anions, [Zn(n)(CN)(2n+1)](-) (1 < or = n < or = 27) and [Cd(n)(CN)(2n+1)](-) (n = 1, 2, 8-27, and possibly 29, 30). Cations Hg(CN)(+) and [Hg(2)(CN)(x)](+) (x = 1-3), and anions [Hg(CN)(x)](-) (x = 2, 3), are produced from Hg(CN)(2). Irradiation of Fe(III)[Fe(III)(CN)(6)] x xH(2)O gives the anions [Fe(CN)(2)](-), [Fe(CN)(3)](-), [Fe(2)(CN)(3)](-), [Fe(2)(CN)(4)](-), and [Fe(2)(CN)(5)](-). When Ag(3)[Fe(CN)(6)] is ablated, [AgFe(CN)(4)](-) and [Ag(2)Fe(CN)(5)](-) are observed together with homoleptic anions of Fe and Ag. The additional heterometallic complexes [AgFe(2)(CN)(6)](-), [AgFe(3)(CN)(8)](-), [Ag(2)Fe(2)(CN)(7)](-), and [Ag(3)Fe(CN)(6)](-) are observed on ablation of Ag(2)[Fe(CN)(5)(NO)]. Homoleptic anions [Co(n)(CN)(n+1)](-) (n = 1-3), [Co(n)(CN)(n+2)](-) (n = 1-3), [Co(2)(CN)(4)](-), and [Co(3)(CN)(5)](-) are formed when anhydrous Co(CN)(2) is the target. Ablation of Ag(3)[Co(CN)(6)] yields cations [Ag(n)(CN)(n-1)](+) (n = 1-4) and [Ag(n)Co(CN)(n)](+) (n = 1, 2) and anions [Ag(n)(CN)(n+1)](-) (n = 1-3), [Co(n)(CN)(n-1)](-) (n = 1, 2), [Ag(n)Co(CN)(n+2)](-) (n = 1, 2), and [Ag(n)Co(CN)(n+3)](-) (n = 0-2). The Ni(I) species [Ni(n)(CN)(n-1)](+) (n = 1-4) and [Ni(n)(CN)(n+1)](-) (n = 1-3) are produced when anhydrous Ni(CN)(2) is irradiated. In all cases, CN(-) and polyatomic carbon nitride ions C(x)N(y)(-) are formed concurrently. On the basis of density functional calculations, probable structures are proposed for most of the newly observed species. General structural features are low coordination numbers, regular trigonal coordination stereochemistry for d(10) metals but distorted trigonal stereochemistry for transition metals, the occurrence of M-CN-M and M(-CN-)(2)M bridges, addition of AgCN to terminal CN ligands, and the occurrence of high spin ground states for linear [M(n)(CN)(n+1)](-) complexes of Co and Ni.     

Increasing the ordering temperatures in oxalate-based 3D chiral magnets: the series [Ir(ppy)2(bpy)][M(II)M(III)(ox)3] x 0.5 H2O (M(II)M(III) = MnCr, FeCr, CoCr, NiCr, ZnCr, MnFe, FeFe); bpy = 2,2'-bipyridine; ppy = 2-phenylpyridine; ox = oxalate dianion)

The synthesis, structure, and physical properties of a novel series of oxalate-based bimetallic magnets obtained by using the Ir(ppy)2(bpy)]+ cation as a template of the bimetallic [M(II)M(III)(ox)3]- network are reported. The compounds can be formulated as [Ir(ppy)2(bpy)][M(II)Cr(III)(ox)3] x 0.5 H2O (M(II) = Ni, Mn, Co, Fe, and Zn) and [Ir(ppy)2(bpy)]-[M(II)Fe(III)(ox)3] x 0.5 H2O (M(II) = Fe, Mn) and crystallize in the chiral cubic space group P4(1)32 or P4(3)32. They show the well-known 3D chiral structure formed by M(II) and M(III) ions connected through oxalate anions with [Ir(ppy)2(bpy)]+ cations and water molecules in the holes left by the oxalate network. The M(II)Cr(III) compounds behave as soft ferromagnets with ordering temperatures up to 13 K, while the Mn(II)Fe(III) and Fe(II)Fe(III) compounds behave as a weak ferromagnet and a ferrimagnet, respectively, with ordering temperatures of 31 and 28 K. These values represent the highest ordering temperatures so far reported in the family of 3D chiral magnets based on bimetallic oxalate complexes.     

Separation and enrichment of arsenic(V) with composite resin beads containing magnetite crystals.

The adsorption of arsenic(V) was investigated using macroporous resin beads containing magnetite crystals. Arsenic(V) was favorably adsorbed at pH 2-9, where the distribution coefficients were larger than 10(3). The maximum capacity was 0.050 mmol/g. Metal cations including Ca(II), Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and La(III) did not give serious interference at 10(-4) M level. Diluted arsenic(V) was collected with a packed column, and the retained arsenic(V) was quantitatively eluted out with 1 M NaOH.