In situ sensing of metal ion adsorption to a thiolated surface using surface plasmon resonance spectroscopy

The kinetics of the adsorption of metal ions onto a thiolated surface and the selective and quantitative sensing of metal ions were explored using surface plasmon resonance (SPR) spectroscopy. The target metal ion was an aqueous solution of Pt2+ and a thin-gold-film-coated glass substrate was modified with 1,6-hexanedithiol (HDT) as a selective sensing layer. SPR spectroscopy was used to examine the kinetics of metal ion adsorption by means of the change in SPR angle. The selectivity of the thiolated surface for Pt2+ over other divalent metal ions such as Cu2+, Ni2+, and Cd2+ was evident by the time-resolved SPR measurement. SPR angle shift, deltatheta(SPR), was found to increase logarithmically with increasing concentration of Pt2+ in the range of 1.0 x 10(-5)-1.0 mM. The rate of Pt2+ adsorption on HDT observed at both 0.1 and 1 mM Pt2+ accelerates until the surface coverage reaches approximately 17%, after which the adsorption profile follows Langmuirian behavior with the surface coverage. The experimental data indicated that heavy metal ions were adsorbed to the hydrophobic thiolated surface by a cooperative mechanism. A mixed self-assembled monolayer (SAM) composed of HDT and 11-mercaptoundecanoic acid was used to reduce the hydrophobicity of the thiol-functionalized surface. The addition of hydrophilic groups to the surface enhanced the rate of adsorption of Pt2+ onto the surface. The findings show that the adsorption of metal ions is strongly dependent upon the hydrophilicity/hydrophobicity of the surface and that the technique represents an easy method for analyzing the adsorption of metal ions to a functionalized surface by combining SPR spectroscopy with a SAM modification.     

The use of amidoximated cellulose for the removalof metal ions and dyes from waste waters

The adsorption of metal ions such as Cu(II), Cr(III), Cd(II) and Ni(II)and dyes such as Acid Blue 25, Calmagite and Eriochrome Blue Black Bis performed onto amidoximated cellulose (Am-Cell). Different ways are possible for theadsorption of these pollutants onto Am-Cell : adsorption of each pollutantaloneon the support, or cumulative adsorption of both metal ions and dyes on the samesupport. In the last case, the pollutants may be adsorbed simultaneously from aunique solution, or successively from two different solutions, whatever theorder. Am-Cell loaded or not with metal ions shows a high capacity for dyeadsorption. Ternary complexes involving metal/dye/amidoxime are formed. Theobserved stoichiometries are 1/1/1 with Cu(II), Cr(III) and Cd(II) ions and1/1/2with Ni(II) ion. A quasi-total and specific desorption of either metal ions (bytreatment with ethylenediaminetetracetic salt) or of dyes (by heating inaqueoussolution) is possible from these ternary complexes. Concerning the dyes, manysuccessive adsorption/desorption cycles are possible without a noticeablechange in the adsorption capacity.     

Ion-exchange separation and spectrophotometric determination of traces of gold

Summary A combined ion-exchange — spectrophotometric method has been developed for the separation and determination of traces of Au(III) in seven metal ions: Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Se(IV) and Cd(II). Au(III) is adsorbed selectively on a DEAE column from dilute chloride solution, while other metal ions pass through the column. Au(III) is recovered by elution with 1M hydrochloric acid. Traces of Au(III) in the effluent are determined by a new spectrophotometric method, which is based on the formation and extraction of Au(III) — azide — methylene blue complex. Separations of traces of Au(III) from 1000-fold of Pd(II) and Pt(IV) and 10000-fold of Hg(II) are also effected on a DEAE column in mixed methanol 1M hydrochloric acid medium (8 2). While Pd(II), Pt(IV) and Hg(II) are retained on the column, Au(III) adsorbs very weakly, so that the separations can be accomplished easily.

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Zusammenfassung Eine mit Ionenaustausch kombinierte spektrophotometrische Methode zur Trennung und Bestimmung von Goldspuren neben sieben verschiedenen Metallionen wurde ausgearbeitet, nämlich neben Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Se(IV) und Cd(II). Das Gold wird an einer Säule aus Diäthylaminoäthylzellulose (DEAE) aus verdünnter Chloridlösung adsorbiert, wobei die anderen Metalle die Säule passieren. Durch Elution mit 1-m Salzsäure wird das Gold wieder gewonnen. Goldspuren im Effluenten werden mit Azid und Methylenblau komplex gebunden und so spektrophotometriert. Von der 1000fachen Menge Pd(II) und Pt(IV) sowie der 100000fachen Menge Hg(II) können Goldspuren auch aus Methanol + 1-m Salzsäure (12) mit einer DEAE-Säule abgetrennt werden. Während Pd(II), Pt(IV) und Hg(II) an der Säule festgehalten werden, wird Au(III) nur sehr schwach adsorbiert, so daß die Trennung leicht gelingt.

     

Block copolymer micellization induced microphase mass transfer: partition of Pd(II), Pt(IV) and Rh(III) in three-liquid-phase systems of S201-EOPO-Na2SO4-H2O

Three-liquid-phase partitioning of Pd(II), Pt(IV) and Rh(III) in systems of S201(diisoamyl sulfide)/nonane-EOPO(polyethylene oxide-polypropylene oxide random block copolymer)-Na(2)SO(4)-H(2)O was investigated. Experimental results indicated that the selective enrichment of Pd(II), Pt(IV) and Rh(III) respectively into the S201 organic top phase, EOPO-based middle phase and Na(2)SO(4) bottom phase was achieved by control over the phase behavior of the three-liquid-phase systems (TLPS). The microphase mass transfer behavior of Pt(IV), Pd(II) and Rh(III) was closely related to the micellization of EOPO molecules. A suggested micro-mechanism model and a mass transfer model describe the micellization of EOPO molecules and the effect on mass transfer of platinum ions across the microphase interfaces. The salting-out induced continuous dehydration and ordered arrangement of the hydrophilic PEO segments in amphiphilic EOPO micelle, and these are the main driving forces for mass transfer of platinum metal ions onto the exposed activity sites of the dehydrated PEO segments. The differences in microphase interfacial structure of EOPO micelles are crucial for the efficient separation between Pt(IV), Pd(II) and Rh(III).     

Spectrometric Studies on the Complexation of Pd(II), Fe(III) and Pt(IV) with mandelazo I

Abstract

A spectrometric study of the reaction between Pd(II), Fe(III) and Pt(IV) ions, and Mandelazo I was carried out. The optimum conditions favouring the formation of the complexes are extensively investigated. The stoichiometry of the complexes formed in solution (1:2, 1:1, 1:1), their apparent stability constants (5.45 × 10⁹, 2.39 × 10⁶, 4.12 × 10⁵) and the ranges for obedience to beer's law (0.2 – 6.4, 0.25 – 7.0, 1.5 – 42.0 μg/mL) are reported for Pd(II), Fe(III) and Pt(IV), respectively. The effect of some metal ions including Cu(II), Zn(II), Mn(II), Cd(II), Hg(II), Co(II), Ni(II), Be(II), Al(III), Th(IV) and U(VI), on the maximum absorbance of the formed complexes was also investigated.     

Selection of the sample composition for the selective preconcentration of some platinum group metal ions by Donnan dialysis

The possibility of selective preconcentration of platinum group metal ions by Donnan dialysis was investigated. The effect of sample matrix (glycine) on self diffusion of the following platinum group metal ions Pt(IV), Pd(II), Rh(III), Ir(III) and Ir(IV) was determined. To separate a sample from the receiver electrolyte (0.5M NH₄Cl), anion or cation-exchange membrane were used. Excellent selective preconcentration of Pd(II) in the sample and Ir(III) in the receiver solution was achieved. Experiments performed enable to draw some conclusion on the charge sign of glycinepalladium complexes.     

Luminol-K2S2O8体系中金属离子化学发光行为的研究

报导了在自行设计的流动注射式化学发光分析仪上,对Luminal-K2S2O8体系中32种金属离子的化学发光行为的系统研究.确定了对金属离子的最优测定条件以及大多数金属离子的检出极限和线性范围.     

Synthesis of N-Methyl-2-Thioimidazole Resin and Its Complex Behavior for Noble Metal Ions

The functional group capacity and the percentage of functional group conversion of crosslinked polystyrene resin bearing N-methyl-2-thioimidazole (MTIR) synthesized under optimum conditions are as high as 4.08 mmol/g resin and 96.0%, respectively. The apparent activation energies of sorption of MTIR for Au(III) and Pt(IV) are 13.1 and 13.4 kJ/mol, respectively. The sorption behavior of MTIR for Au(III), Pt(IV), and Pd(II) obeys the Freundlich and Langmuir isotherms. The sorption capacities of MTIR for Au(III), Pt(IV), and Pd(II) are as high as 4.33, 2.12, and 2.33 mmol/g resin, respectively. Au(III), Pt(IV), and Pd(II) adsorbed on MTIR can be eluted quantitatively by the eluant. The resin can be regenerated easily and reused without an obvious decrease in the sorption capacity for Au(III) and Pd(II). The resin has high sorption selectivity for noble metal ions. Au(III) can be separated quantitatively in the presence of high concentrations of Cu²⁺, Fe³⁺, Ni²⁺, and Mn²⁺. The recovery of platinum from the spent industrial catalysts is 98.6% by MTIR. The preconcentration and separation of palladium and platinum from the anode deposits of electrolysis of crude copper have been investigated. The resin may have potential industrial uses.     

Highly efficient adsorbing noble metal ions by 3,4-dihydroxycinnamic acid-modified activated carbon

A method was established for the preconcentration of trace Au(III), Pd(II) and Pt(IV) by activated carbon modified with 3,4-dihydroxycinnamic acid. The separation and preconcentration conditions of analytes were investigated, such as effects of pH, the contacting time, the sample ?ow rate and volume, the elution condition and the interfering ions. At a pH of 1.0, the maximum static sorption capacity of the sorbent was found to be 374.8, 96.6 and 137.5 mg g^?1 for Au(III), Pd(II) and Pt(IV), respectively. The adsorbed metal ions were effectively eluted with 2.0 mL of 4% thiourea in 0.5 M HCl solution and determined by inductively coupled plasma optical emission spectrometry. The detection limit (3σ) of this method defined by IUPAC was found to be 0.12, 0.18 and 0.32 ?g L^?1 for Au(III), Pd(II) and Pt(IV), respectively. The relative standard deviation (RSD) was lower than 3.0% (n = 8) towards standard solutions. The method has been validated by analysing certified reference materials and successfully applied to the determination of trace Au(III), Pd(II) and Pt(IV) in road sediments samples.     

Synthesis of new ionic β-cyclodextrin polymers and characterization of their heavy metals retention

In this study, a new aqueous insoluble ionic β-cyclodextrin polymer (PYR), synthesized by reaction of β-cyclodextrin with pyromellitic anhydride [1], is characterized by IR spectroscopy, showing typical cyclodextrin and carboxylic absorptions. pH-metric titrations of the acidic functions with standard NaOH solutions followed by a refinement of protonation constants, with specific software for equilibrium in solution, have been performed. Through this approach, the pK _a values of the functional groups have been calculated. The complexation capabilities of PYR towards metal ions [Al(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Cd(II), Pt(IV), Tl(I), and U(IV)] have been evaluated in aqueous solution (pH 3–5). The retention is mainly pH dependent and higher than 70% for Al(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Cd(II) and U(IV). For Tl(I) and Pt(IV) the retention is about 60% and 40% respectively.     

Sorption of palladium(II), rhodium(III), and platinum(IV) on Fe(3)O(4) nanoparticles

The adsorption of palladium(II), rhodium(III), and platinum(IV) from diluted hydrochloric acid solutions onto Fe(3)O(4) nanoparticles has been investigated. The parameters studied include the contact time and the concentrations of metals and other solutes such as H(+) and chloride. The equilibrium time was reached in less than 20 min for all metals. The maximum loading capacity of Fe(3)O(4) nanoparticles for Pd(II), Rh(III), and Pt(IV) was determined to be 0.103, 0.149, and 0.068 mmol g(-1), respectively. A sorption mechanism for Pd(II), Rh(III), and Pt(IV) has been proposed and their conditional adsorption equilibrium constants have been determined to be logK=1.72, 1.69, and 1.84, respectively. Different compositions of eluting solution were tested for the recovery of Pt(IV), Pd(II), and Rh(III) from Fe(3)O(4) nanoparticles. It was found that 0.5 mol L(-1) HNO(3) can elute all of the metal ions simultaneously, while 1 mol L(-1) NaHSO(3) was an effective eluting solution for Rh(III), and 0.5 mol L(-1) NaClO(4) for Pt(IV). In competitive adsorption, the nanoparticles showed stronger affinity for Rh(III) than for Pd(II) and Pt(IV).     

Adsorption behaviour of a number of metals on weakly basic ion-exchangers in methanol-hydrochloric acid mixtures

Many metals are not strongly adsorbed on DEAE-cellulose from aqueous hydrochloric acid media. However, some metals can be adsorbed on DEAE-cellulose from methanol-hydrochloric acid media. Distribution coefficients of Zn, Cd, Hg(II) and Bi(III), which show pronounced adsorption, are presented as functions of the methanol and the acid concentrations. Differences in the distribution coefficient between the four metals and a considerable number of other metals are large enough to permit good separations on columns. Among the platinum group metals, Pd(II), Ir(IV) and Pt(IV) are adsorbed from the mixed solvents and may be separated from large quantities of base metals such as Fe(III), Co(II), Ni and Cu(II).     

Application of a macroporous resin containing imidazoline groups to preconcentration and separation of gold, platinum and palladium prior to ICP-AES determination

A new functional resin with a long functional side chain was synthesized by modification of aminated macroporous poly(vinyl chloride) resin with cyanoethylene and ethylenediamine. Traces of Au(III), Pt(IV) and Pd(II) in aqueous solution were quantitatively adsorbed in the acidity range of pH 4 and C(H(+)) 3 M. The rate of equilibration is high; Cu(2+), Fe(3+), Ni(2+), etc. exhibit little interference on the adsorption of the sought noble metals. The saturated adsorption capacities for Au(III), Pt(IV), Pd(II) and Ir(IV) in 2 M HCl were 4.0, 1.57, 2.26, 1.85 mmol g(-1). Adsorbed ions can be quantitatively desorbed by 4% thiourea +0.25 M H(2)SO(4). The resin has good reusability, and can be used for preconcentration and separation of Au(III), Pt(IV) and Pd(II) prior to their determination by ICP-AES with satisfactory results.     

Preconcentration/Separation of Some Metal Ions Using Sodium Dodecyl Sulfate Coated Alumina Modified with Bis(5‐bromo‐2‐hydroxy‐benzaldehyde)‐2‐methyl‐1,5‐pentane Diimine (BBHBPDI) Prior to Their Flame‐AAS Determination

Preconcentration/separation of Co(II), Fe(III), Pb(II), Cr(III), Cu(II) and Cd(II) ions using bis(5‐bromo‐2‐hydroxy‐benzaldehyde)‐2‐methyl‐1,5‐pentane diimine (BBHBPDI) on SDS coated alumina has been reported. The influences of the analytical parameters including pH, ligand and SDS amount, type and concentration of eluent and sample volume on metal ions recoveries were investigated. At optimum values of all variables the relative standard deviation are between 2.5–2.7 and preconcentration factor was 375, while recoveries for all understudy metal ions are higher than 95%, determination limits are between 1.5–2.7. The method has been successfully applied to determination of Co(II), Fe(III), Pb(II), Cr(III), Cu(II) and Cd(II) ions content in some real samples.     

Synthesis of Polyacrylaminothiourea Chelating Fiber and Properties of Concentration and Separation of Trace Noble Metal Ions from Samples

A novel polyacrylaminothiourea chelating fiber was synthesized simply and rapidly from nitrilon (an acrylonitrile-based synthetic fiber), which was applied to preconcentrate and separate of trace amount of Au(Ⅲ）,Pt(Ⅳ）,Pd(Ⅳ） and Ir (Ⅳ） ions from solution of samples.The analyzed ions can be quantitatively concentrated by the fiber up to a flow rate of 20.0mL/min at pH2, and can also be desorbed with 15 mL of 4mol/L HCl 3% thiourea from the fiber column with recoveries of 96.5%-100%.The chelating fiber can be reused for ten times,the recoveries of these ions are still over 92%,and hundred to thousand times of excess of Fe(Ⅲ）,Al（Ⅲ）,Ca(Ⅱ），Mg（Ⅱ）,Ni(Ⅱ）,Mn（Ⅱ),Cu(Ⅱ），Zn(Ⅱ），and Cd(Ⅱ） cause no interference on the determination of the analyzed ions by inductively-coupled plasma atomic emission spectrometry (ICP-AES).The static saturation adsorption capacities of the fiber for the analytes are in the range of 1.15-2.80mmol/g.The relative standard deviations for the determination of 20.0ng/mL each of Au(Ⅲ）,Pt(Ⅳ）,Pd(Ⅳ）and Ir(Ⅳ） are in the range of 0.7%-3.0%.The recoveries for test from standard additions to real solution samples are between 96% and 100%.The concentration of each ion in powder sample detected by the method is in good agreement with the certified value.     

Selective solid-phase extraction and separation of trace gold, palladium and platinum using activated carbon modified with ethyl-3-(2-aminoethylamino)-2-chlorobut-2-enoate

Activated carbon was chemically modified with ethyl-3-(2-aminoethylamino)-2-chlorobut-2-enoate to obtain a material for selective solid-phase extraction of trace Au(III), Pd(II) and Pt(IV) prior to their determination by inductively coupled plasma atomic emission spectrometry. Experimental conditions such as effects of pH, shaking time, sample flow rate and volume, elution and interfering ions were studied. The ions Au(III), Pd(II) and Pt(IV) can be quantitatively adsorbed on the new sorbent from solution of pH 1. The adsorbed ions were then eluted with 0.1 mol L^?1 hydrochloric acid and containing 4% thiourea. Many common ions do not interfere. The adsorption capacity of the material is 305, 92, and 126 mg g^?1 for Au(III), Pd(II) and Pt(IV), respectively, and the detection limits are 5, 11 and 9 ng mL^?1. The relative standard deviation is less than 3.0% (n?=?8) under optimum conditions. The method was validated by analyzing two certified reference materials and successfully applied to the preconcentration and determination of these ions in actual samples with satisfactory results.

Liquid extraction of noble metal ions with bis(α-aminophosphonates)

Extraction of Au(III), Pt(IV), and Pd(II) ions from hydrochloric acid media with solutions of two bis(aminophosphonates), such as N,N-bis(dipentoxyphosphorylmethyl)octylamine and N,N′-bis[[(dioctyloxyphosphoryl)methyl]butylamine], in chloroform and xylene was investigated. Both these extractants proved to be highly effective for Au(III) ions in a wide acidity range, which allows these ions to be separated from other noble metal ions with a high degree of selectivity. At the same time, Pt(IV) and Pd(II) ions cannot be separated from one another with the extractants studied. The selectivity of their separation from Fe(III), Cu(II), Co(II), and Ni(II) metal ions is, too, not high. The reasons for these results lie in the specific structural features of the extractants, which predetermine the extraction mechanism.     

Hydrogen chemical ionization mass spectrometry of metalloporphyrins

The hydrogen chemical ionization (H₂ CI) mass spectra of a range of metal(II) (Ni, Cu, Co, Pt), metal (III) (Al, Mn, Ga, Fe (bearing a single axial ligand)) and metal(IV) (Si, Ge, Sn (bearing two axial ligands) and V (as V?O²⁺)) porphyrins have been determined, The spectra are highly dependent on the coordinated metal, rather than the axial ligand(s) (where present). Ni(II), Cu(II), Mn(II or III), Ga(III), Ge(IV), Fe(III) and Sn(IV) porphyrins fragment via hydrogenation and demetallation, followed by cleavage of the resulting porphyrinogens at the meso(bridge) positions to give mono- and di-pyrrolic fragments. Tripyrrolic fragments are also observed in the case of Ni(II), Cu(II) and Sn(IV). Fragmentations of this type are similar to those observed for free-base porphyrins. In the case of Pt(II), Co(II), Al(III), Si(IV) and V(IV) (as vanadyl), the dipyrrolic fragment ions are either very weak or completely absent; hence their H₂CI spectra contain limited structural information. This variable CI behaviour may be related to the relative stabilities of the metalloporphyrins together with the multiple stable valency states exhibited by several metals.     

Thermogravimetric analysis of some metal thiocarbonates and sulphides obtained with potassium thiocarbonate (PTC) reagent

The thiocarbonates of K(I), Tl(I), Pb(II), Cd(II), Cu(II), Co(II), Ni(II), Zn(II), Fe(II) and the sulphides of Ag(I), Cu(II), Cd(II), Hg(II), Bi(III), Mo(VI), Pt(IV), Au(III), V(V), Se(IV), Te(IV), As(III, V), Sb(III) have been studied by thermogravimetric analysis. These studies not only confirm the purity of the precipitated products obtained with PTC but also determine correct temperature ranges for the precipitates to attain constant weight, thereby affording gravimetric evaluations of even mg quantities of the metal ions studied. Purity of precipitated products was made possible with the technique of precipitation from homogeneous solution based on the PTC reagent as precipitant.     

Chromatographic separation by a new chelating resin containing β-hydroxydithiocinnamic acid

Summary The distribution coefficients of Ag(I), Au(III), Cd(II), Cu(II), Fe(III), Hg(II), Ni(II), Pb(II), Pt(IV), and Zn(II) on a new chelating resin containing -hydroxydithiocinnamic acid at various acidity were studied. In the strongly acidic region, the resin shows high affinity for Ag(I), Hg(II), Au(III) and Pt(IV) and high resistance against air oxidation. The effect of diverse foreign ligands on the sorption of metal ions and the possibility of application to speciation studies with this resin were also considered. Some quantitative separations of Cd-Cu-Pb, Cu-Au and Au-Pt with this resin column were described. Detection of the chromatography system was carried out via post column derivatisation of the column effluent with PAR at 520 nm or direct UV detection of the chloride complexes at 215 nm.