镓在氨基吡啶树脂上的吸附行为及机理

前文已报道了氨基吡啶树脂对AuCl_4~-、PtCl_6~(2-)的吸附性。本文报道4-氨基吡啶树脂对镓的吸附行为与机理。在6mol/L HCl条件下,对镓的氯络阴离子(GaCl_4~-)有很好的吸附性。并能定量洗脱。测得静态吸附容量为351.15mg/g树脂,用化学法及红外光谱等方法,测得4-氨基吡啶树脂吸附镓(Ⅲ)的基本参数。     

2,3-Dihydroxypyridine Loaded Amberlite XAD-2 (AXAD-2-DHP): Preparation, Sorption–Desorption Equilibria with Metal Ions, and Applications in Quantitative Metal Ion Enrichment from Water, Milk and Vitamin Samples

2,3-Dihydroxypyridine loaded (via –N=N–linker) Amberlite XAD-2 (AXAD-2-DHP) was prepared and characterized by elemental analyses, TGA and FT-IR spectra. It (1g packed in a column of 1cm diameter; surface area 135.5m²g^–1) was found to be an effective solid phase sorbent for enriching Zn²⁺, Mn²⁺, Ni²⁺, Pb²⁺, Cd²⁺, Cu²⁺, Fe³⁺ and Co²⁺ at pH 3.5 to 7.0 using flow rates between 1.0–5.0mLmin^–1. For desorption (recovery 97.0–99.8%) of the metal ions, 8 to 10mL of 2.0molL^–1 HCl or 1.5molL^–1 HNO₃ at a flow rate of between 2.0 and 4.0mLmin^–1 were found most suitable. The t_1/2 (time for 50% sorption) is between 2 and 10min when a 50mL solution (containing a total amount of metal of 2mg) was equilibrated with 0.5g of resin. Sorption of all metal ions except Pb²⁺ follows the Langmuir model, whereas for Pb the data fits with the Freundlich model. The sorption capacity is between 60.7 (for Cd) and 406.7 (for Cu) µmolg^–1. The resin can withstand an acid concentration of 6molL^–1 and can be reused for thirty cycles of sorption–desorption. The preconcentration factor varies between 100 and 300. For Cd, Ni and Cu the sorption capacity of 2,3-dihydroxypyridine loaded cellulose is lower than that of the present resin. The tolerance limits of electrolytes, humic acid, complexing agents, Ca²⁺ and Mg²⁺ in the enrichment of all metal ions are reported. The limits of detection are 3.88, 5.37, 8.72, 13.88, 4.71, 1.24, 0.59 and 0.30µgL^–1 for Zn²⁺, Mn²⁺, Ni²⁺, Pb²⁺, Cd²⁺, Cu²⁺, Fe³⁺ and Co²⁺, respectively. The calibration curves for flame AAS determination were linear in the ranges 0.018–1.0, 0.067–5.0, 0.2–5.0, 0.9–20, 0.028–2.0, 0.077–5.0, 0.19–10 and 0.1–3.5µgmL^–1, respectively. All the eight metal ions in river and synthetic water samples, Co in vitamin tablets and Zn in milk samples have been quantitatively enriched with Amberlite XAD-2-DHP and determined by flame atomic absorption spectrometry.     

ADSORPTION OF 2,4-D ON MODIFIED HYPERCROSSLINKED POLYSTYRENE （NDA-99） AND XAD-4 RESIN

The adsorption behavior of pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution has been investigated using a hypercrosslinked polystyrene adsorbent (NDA-99) modified by dimethylamine group as well as a nonionic macroporous adsorbent (XAD-4). The Langmuir and Freundlich isotherm models were employed to fit the experimental data to describe adsorption mechanism. It shows that NDA-99 resin exhibits an adsorption affinity for 2,4-D higher than XAD-4 resin owing to its exceptional micropore structure and the amine group of the hypercrosslinked matrix.Further studies indicate that the hydrogen bonding interaction and the stronger π-π conjugation play a significant role in the course of the adsorption of 2,4-D on NDA-99 resin, which is in agreement with the IR spectroscopic results and the △E values of HOMO (the highest occupied molecular orbit) of adsorbent and LUMO (the lowest unoccupied molecular orbit) of adsorbate calculated from the MINDO/3 model.     

凝胶型苯乙烯系离子交换树脂的强度及抗渗透性的影响因素研究 (I)

本文就单体组成中不同引发剂，链转移剂，环二烯，烯丙基类化合物和氧气等对凝胶型苯乙烯系阳离子交换树脂的强度和抗渗透性的影响进行了系统研究。结果显示，采用0．30％的过氧化2－乙基己酸叔丁酯（OT）和0．01％的过氧化苯甲酸特丁酯（CP）代替过氧化二苯甲酰（BPO作引发剂，或者加入0．02％的链转移剂十二烷基硫醇，均能够在一定程度上改善共聚物珠粒的结构均匀性，提高其合成的离子交换树脂的磨后圆球率和抗渗透性能。     

新型Ni—Pd/碳化树脂催化剂的制备及在微量测定有机氧元素中的应用

本文报道一种新型Ni—Pd／碳化树脂催化剂的制备方法，用该法制备的催化剂具有高金属分散度和高机械强度，用于库仑法微量测定有机氧元素取得满意结果。文中对Ni和Pd颗粒在催化剂上表面形貌和分布、催化活性等作了初步探讨。     

Shipboard analysis of picomolar levels of manganese in seawater by chelating resin concentration and chemiluminescence detection

A new shipboard analytical method for determining picomolar levels of manganese in seawater has been developed. The method is based on a combination of chelating resin column extraction and improved chemiluminescence (CL) detection in a closed flow system. In this method, manganese in sample solution is selectively collected on newly-developed iminodiacetate-immobilized chelating resin, and then eluted with acidic solution containing hydrogen peroxide. The resulting eluent is mixed with luminol solution and aqueous ammonia after removal of iron ions by a chelating resin column, and then the mixture is introduced into the CL cell. The manganese concentration is obtained from the CL intensity. The detection limit (3SD) of manganese is 5 pmol L^–1 from 9 mL of seawater sample. The method was applied to seawater samples collected at the Okinawa Trough.     

Synthesis and characterization of poly(4-vinyl,2′-carboxybensophenone)

The synthesis and characterization of poly(4-vinyl,2′-carboxybenzophenone) ion exchange resin is described. This resin displays a remarkably high capacity for Cu²⁺. Control of pH permits selective adsorption and estimation of Fe³⁺. This ion-exchanger is quite stable to loading acid washing cycles. © 1995 John Wiley & Sons, Inc.     

Biomimetic formation of gramicidin S by dimerization-cyclization of pentapeptide precursor on solid support

The biomimetic formation of gramicidin S, cyclo(-d-Phe-Pro-Val-Orn-Leu-)₂, by the dimerization and cyclization of pentapeptide precursor without the protection of δ-amino group of the Orn residue was examined on a solid support. The cyclization of H-d-Phe-Pro-Val-Orn-Leu-oxime on a resin with an oxime group of 0.62 mmol/g in 1,4-dioxane directly gave gramicidin S in a 50% yield. The dimerization-cyclization mode on the solid support was similar to that of the biosynthesis of gramicidin S on an enzyme.     

Vibrational spectroscopic encoding of polystyrene-based resin beads: converting the encoding peaks into barcodes

A detailed approach is described for the vibrational spectroscopic encoding of polystyrene-based resin beads by converting the infrared absorption peaks suitable for encoding (encoding peaks) into barcodes. Based on combining the FT-IR measurements and the quantum-chemical computations, the vibrational characteristics of p-tert-butylstyrene monomer, polystyrene and poly(p-tert-butylstyrene) resin beads are analyzed, which are helpful for the selection of encoding peaks. The vibrational spectroscopic encoding of polystyrene-based resin beads could be obtained by converting the wavenumber, intensity and full width at half maximum (FWHM) of the encoding peaks into barcodes automatically through a computer program designed in our laboratory.     

Solid phase extractive preconcentration of uranium(VI) using quinoline-8-ol anchored chloromethylated polymeric resin beads

A new chelating polymeric sorbent has been developed using Merrifield chloromethylated resin anchored with quinoline-8-ol (HQ). The modified polymeric resin was characterized by FT-IR spectroscopy and elemental analysis. The HQ anchored resin showed superior binding affinity for U(VI) over Th(IV) and La(III). The influence of various physicochemical parameters on the recovery of U(VI) were optimized by both static and dynamic methods. The phase exchange kinetic studies performed for U(VI) revealed that <5 min was sufficient for reaching equilibrium metal ion sorption. The maximum sorption capacity of HQ anchored resin for U(VI) was found to be 120.30 mg g⁻¹ of resin which is higher than other solid phase extraction sorbents reported so far excepting N,N-dibutyl, N′-benzoyl thiourea sorbed Amberlite XAD-16. The developed HQ anchored polymeric resin is highly selective as none of the extraneous species were found to have any deleterious effect. Solid phase extraction (SPE) studies performed using HQ anchored polymeric resin offered enrichment factor of 100 and the lowest concentration below which recoveries become non-quantitative is 5 μg l⁻¹. The accuracy of the developed SPE method in conjunction with Arsenazo III procedure was tested by analyzing marine sediment (MESS-3) and soil (IAEA–Soil 7) reference materials. Furthermore, the above procedure has been successfully employed for the analysis of real soil and sediment samples.