Xingyin Luo

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.

Synthesis and characterization of a macroporous poly(vinyl-aminoacetone) chelating resin for the preconcentration and separation of traces of gold, palladium, rhodium and ruthenium

An inductively coupled plasma atomic-emission spectrometry (ICP-AES) procedure is established with a new macroporous poly(vinyl-aminoacetone) chelating resin (PVAA) for preconcentration and separation of traces of Au(III), Pd(IV), Rh(III) and Ru(III) from sample solutions. The conditions of quantitative enrichment and desorption of these analytes from PVAA columns, including investigations of the stability, the regeneration capabilities and the adsorption capacities of that collector, are discussed. Moreover, interferences of foreign ions on the analytes are not observed and analysis of a real sample is performed with reliable results. Recoveries of these elements added to non-ferrous matrices are above 95% with relative standard deviations (RSD) between 2.0 and 4.0%.

Efficiency and mechanism of macroporous poly(vinylthiopropionamide) chelating resin for adsorbing and separating noble metal ions and determination by atomic spectrometry

Abstract A macroporous poly(vinylthiopropionamide) chelating resin was synthesized from spherical poly(vinyl chloride) resin particles and used for the enrichment and separation of trace noble metal ions. Trace Au(III), Pt(IV) and Pd(II) in sample solutions can be enriched quantitatively in the range 5 M HClpH 9 with recoveries > 96%, and the recovery of trace Ir(IV) at pH 1–9 was > 93%; however, the adsorption of Rh(III) and Ru(III) at pH 3–6 was −1 , the recoveries of Au, Pt, Pd eluted with 6% thiourea-1 M HCl and Ir with 6 M HCl were > 96%. The adsorption capacity of the resin was 978 ng g −1 for Au, 288 mg g −1 for Pt, 455 mg g −1 for Pd and 10 mg g −1 for Ir. When the resin was reused ten times, the recoveries of the above ions on enrichment were still > 92% and a 100-fold excess of other ions caused little interference in the determination of the ions. The eluted ions were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The lowest concentrations determined were 0.040 μg ml −1 for Au, Pt and followed by Zeeman-effect atomic absorption spectrometry or ICP-AES were in good agreement with the certified values. The structures of the resin, investigated by Fourier transform IR spectrometry and electron spectroscopy revealed that Au, Pt and Pd ions were chelated mainly with the thioketo form of the thiorpropionamide group in the resin, forming a quadridentate chelate.

Synthesis and efficiency of a polyacrylacylisothiourea chelating fibre for the preconcentration and separation of trace amounts of gold, palladium and ruthenium from solution samples

A polyacrylacylisothiourea chelating fibre was synthesized using polyacrylonitrile fibre as a starting material, and the structure of the chelating fibre was determined by infrared spectrometry. The parameters influencing the efficiency of the fibre at concentrating trace amounts of AuIII, PdIV, and RuIII, including acidity, flow rate, adsorption capacity, effect of re-use, interfering ions, and desorption, were investigated. Gold(III), PdIV, and RuIII were enriched and separated from real samples and were detected using inductively coupled plasma optical emission spectrometry with satisfactory results. For concentrations of AuIII, PdIV, and RuIII of 0.008 mg l–1, the relative standard deviation was 1.8% for AuIII, 2.5% for PdIV, and 0.8% for RuIII. The concentrations obtained for these ions in real solution samples by this method were basically in agreement with the given values, with average errors of less than 2.5%. The method is rapid, precise, simple, and convenient to use.

Synthesis of poly(N-aminoethyl)acrylamide chelating fiber and properties of concentration and separation of noble metal ions from samples

A new kind of poly(N-aminoethyl)acrylamide chelating fiber was synthesized from nitrilon (an acrylonitrile-based synthetic fiber) and used for the concentration and separation of traces of noble metal ions from solution. The results showed that 16-80 ng ml (1) of Au(III), Pt(IV), Pd(IV), Ir(IV), Ru(III) and Rh(III) can be quantitatively concentrated by the fiber up to a flow rate of 20 ml min (-1) at pH 3, and can be desorbed quantitatively with an eluting agent from the fiber column with recoveries of 96-100%. For a fiber reused 10 times, the recoveries of these ions were still over 94%, and a 100-1000 times excess of Fe(III), Al(III), Ca(II), Mg(II), Ni(II), Co(II), Cu(II) and Zn(II) caused no interference in the determination of these ions by inductively-coupled plasma atomic emission spectrometry. The capacities of the fiber for the analytes were in the range 0.80-2.62 mol g(-1), The relative standard deviation of the method was between 0.02% and 2.6%. Recoveries of a standard added to a real sample were 96.8-99.2%. The average error for the analysis by this method for a powder sample was 3.5%. The IR spectra of the analyte-bearing fiber showed that these ions coordinated to nitrogen sites in the fiber.

Synthesis of poly(acrylamidrazone-hydrazide) chelating fiber and application of enrichment-separation for traces of indium, tin, chromium, vanadium and titanium from solution samples.

A poly(acrylamidrazone-hydrazide) chelating fiber has been synthesized from polyacrylonitrile fiber and used for enrichment-separation of traces of In(III), Sn(IV), Cr(III), VO(I) and Ti(IV) from solution samples with satisfactory results. These ions (5-250 ng/ml) can be quantitatively enriched (recovery > 95%) by the fiber at a 10 ml/min flow rate in the pH range 4-7, and desorbed quantitatively (recovery > 95%) with 10 ml of 2-5M hydrochloric acid from a fiber column at 6 ml/min flow rate. When the fiber, which had been stored in a glass bottle for about two years and then treated with strong acids (concentrated hydrochloric or nitric acid), was reused 10 times, the recoveries of the above ions by enrichment were still over 94%, and hundred-fold to thousand-fold excesses of Cu(II), Zn(II), Co(II), Ca(II), Mg(II), Fe(III) and Al(III) caused little interference in the determination of these ions by ICP-AES. The lowest concentrations for the proposed method were 50 ng/ml and In and Sn and 5 ng/ml for Cr, V and Ti. The RSD was 1.2-4.0%. The contents of these ions in real solution samples determined by this method were basically in agreement with the certified values of the samples, with average errors below 3.3%. The IR spectra of the fiber adsorbed with Cr(III) or VO(I) showed that Cr(III) or VO(I) combined mainly with nitrogen atoms in the fiber to form a coordination complex.

Synthesis of a morin chelating resin and enrichment of trace amounts of molybdenum and tungsten prior to their determination by inductively coupled plasma optical emission spectrometry

A morin chelating resin was synthesized using aminated poly(vinyl chloride) as the starting material, and the optimum conditions for the synthesis were established. The parameters governing the characteristics of the resin for the adsorption of MoVI and WVI including acidity, flow rate, rate constant, saturated capacity of adsorption, effect of re-use, interfering ions and desorption were investigated. The MoVI and WVI concentrations in standard samples were determined by using inductively coupled plasma optical emission spectrometry, with satisfactory results. For concentrations of MoVI and WVI of 0.4 mg l–1, the relative standard deviation was 2.8% for MoVI and 2.6% for WVI. The structure of the chelating resin was deduced by infrared spectrometry, and the mechanism of the enrichment of MoVI and WVI is discussed.

Synthesis and efficiency of an epoxy-tannin chelating resin for preconcentrating and separating various rare elements

Abstract A new epoxy-tannin chelating resin was synthesized from epoxy resin and used for the preconcentration and separation of rare elements. The acidity, rate, reuse, capacity and interference on the adsorption of ions on the resin as well as the conditions of desorption of these ions from the resin were investigated by means of inductively coupled plasma atomic emission spectrometry (ICP-AES). The composition of the resin and mechanism of enrichment for some ions were discussed. The results show that the relative standard deviations for the determination of 50 ng ml −1 Ga(III), In(III), Bi(III) and Sn(IV), 10 ng ml −1 La(III), Y(III), Cr(III), Ti(IV) and V(V) and 1.0 ng ml −1 Be(II) were in the range of 0.5–4.5%. The contents of these elements in a sample solution from a smelter determined by the new method were in agreement with those values obtained by Zeeman atomic absorption spectrometry with an average error

Application of macroporous poly(vinyl amidine thiocyanate-thiourea) chelate resin for adsorbing and separating trace Cr, V, Ti, Be, Y, La, and Cu—Detection by inductively coupled plasma optical emission spectroscopy

Abstract An ICP-OES method has been developed for use with synthetic macroporous poly(vinyl amidine thiocyanate-thiourea) chelate resin adsorption and separation of trace Cr, V, Ti, Be, Y, La, and Cu ions in solution. The conditions for quantitative enrichment and desorption of the above ions are investigated. The experiments show that the preserved resin is stable for 3 years, may be reused more than 7 times, and can still quantitatively adsorb these ions at pH 4–6. With enrichment factors of 50 and ion concentrations of 0.20 ng/ml for Be(II), 20 ng/ml for Ti(IV) and Cu(II), and 40 ng/ml for Cr(III), V(V), Y(III), and La(III), the recoveries desorbed with 10 ml of 6 m HCl are between 97.5 and 105% and the RSDs are in the range of 4.2–5.9%. A hundred-fold excess of other ions causes little interference in the determination of the ions. The results with enriched wastewater from a smelter plant are 0.19 ng/ml for Be, 19 ng/ml for Ti, 22 ng/ml for Cu, 38 ng/ml for Cr and V, and 42 ng/ml for Y and La ions. Recoveries of added standard are in the range of 97.2–104%. The contents of Be, Ti, Cu, Cr, V, Y, and La in a certified sample determined by the method are in good agreement with the certified values of the sample.

Properties and applications of polyacrylacylisothiourea chelating fiber for preconcentration and separation of trace titanium, vanadium and bismuth

An ICP-OES method using a new poly-acrylacylisothiourea chelating fiber to preconcentrate and separate trace Ti(IV), V(V) and Bi(III) ions from solution samples is established. The results show that 5–25 ng/ml of Ti or V and 50–250 ng/ml of Bi ions in 200–1000 ml of solution can be enriched quantitatively by 0.05 g of the fiber at pH 3 with recoveries over 97%. These ions can be desorbed quantitatively with 10 ml of 4M HC1O4. 100- to 1000-fold excesses of Fe(III), Al(III), Ca(II), Mg(II), Cu(II), Ni(II) and Mn(II) ions cause little interference. The chelating fiber stored for about 2 years can still be used repeatedly for preconcentration and separation of trace Ti, V and Bi ions from solution with above 95% recovery. The RSDs for enrichment and determination of 5 ng/ml of Ti or V and 50 ng/ml of Bi are in the range 2.5–2.8%. The recoveries of added standard in real waste waters and mineral samples are between 96 and 100%, and the concentration found for each ion in the mineral sample was in good agreement with that measured by ETAAS.