Water-Soluble Polyacids with Capability to Remove Metal Ions in Homogenous Phase by Using the Liquid Phase Polymer-Based Retention Technique

Water-soluble polymers containing carboxylic acid and sulfonic acid groups were investigated as polychelatogens under different experimental conditions in view to study their metal ion binding properties, using the liquid-phase polymer-based retention technique. The divalent metal ions investigated were: Co²⁺, Cu²⁺, Zn²⁺, and Cd²⁺. When the pH increased above 3, and especially at pH 5, metal ion retention capability increased as the majority of the functional groups are carboxylate, which can form more stable complexes with the metal ions. The retention capability also depended on the structure of the polyacid and the filtration factor, Z.     

Ultrafiltration of Polymer-Metal Complexes for Metal Ion Removal from Wastewaters

Summary: A case-study using macromolecular metal complexes is described. The results of a process named Polymer Assisted Ultrafiltration (PAUF) for ion removal from various types of waters is reported. The water soluble polymers such as polyetilenimine (PEI), polyacrylic acid (PAA), polyacrylic acid sodium salt (PAASS) and poly(dimethylamine–co–epichlorohydrin–co–ethylenediamine) (PDEHED) as chelating agents, the Cu²⁺ as model ion and five ultrafiltration membranes have been used. The complexing agents were previously tested to establish the binding capacity and the best operating conditions for the process. Among the tested polymers the PEI appeared the most interesting one because its binding mechanism does not involve a counter ion release. It was tested in the simulation of wastewaters treatment containing the Cu²⁺ ion chelated with citric acid; this is a problem of interest in the recycling of water from soil washing operations. The polyethylenimine quantitatively bound the copper-citrate chelate at pH 5.5 and the three component complex was separated by UF membranes producing a permeate with very low metal concentration. The polymer regeneration was carried out with good results by operating with the diafiltration method. The copper ion present in the diafiltration permeate in a form chelated with citric acid was recovered by oxidising the citrate in a membrane photoreactor. The positive results of the described case-study show that Macromolecule-Metal Complexes play a key role for running effectively and selectively the PAUF process for removing metal ions from various type of waters.     

Water-Soluble Polyelectrolytes with Ability to Remove Arsenic

Arsenic species can be removed from aqueous solutions using the liquid-phase polymer-based retention, LPR, technique. The LPR technique removes ionic species by functional groups of water-soluble polyelectrolytes (WSP) and then using a ultrafiltration membrane that does not let them pass through the membrane, thus separating them from the solution. The ability of WSP with groups (R)₄N⁺X⁻ to remove arsenate ions using LPR was studied. The interaction and arsenate anion retention capacity depended on: pH, the quaternary ammonium group's counter ion, and the ratio polymer: As(V), using different concentrations of As(V). Water-soluble polychelates were also used for one-step retention of As(III) in solution. The complex of poly(acrylic acid)-Sn, 10 and 20 wt-% of metal gave a high retention of As(III) species at pH 8, although the molar ratio polychelate: As(III) was 400:1. The enrichment method was used to determine the maximum retention capacity (C) for arsenate anions in aqueous solutions at pH 8. In similar conditions, the values of C were 142 mg g⁻¹ for P(ClAETA) and 75 mg g⁻¹ for P(SAETA). The combined treatment of arsenic aqueous solutions by electrocatalytic oxidation (EO) to convert the species of As(III) to As(V) with the LPR technique quantitatively removed arsenic.     

Water-soluble Polyelectrolytes Contaning Sulfonic Acid Groups with Metal Ion Binding Ability by Using the Liquid Phase Polymer Based Retention Technique

Water-soluble polyelectrolytes from 2-acrylamido-2-methyl-1-propane sulfonic acid (APSA) were obtained by radical polymerization with different comonomers which contain weak acid and neutral groups. These copolymers were investigated as polyelectrolytes and polychelatogens, in view of their metal ion binding properties using the liquid-phase polymer-based retention (LPR) technique under different experimental conditions. The metal ions investigated were: Ag(I), Co(II), Cu(II), Zn(II), Cd(II), and Pb(II). APSA allowed increase metal ion interaction of weak acid, meanwhile did not improve the metal ion interaction of neutral monomers at these experimental conditions. Results indicated that retention capability depended strongly on the structure of the polyelectrolyte, arrangement of comonomers at main chain, pH, and the filtration factor, Z.     

纳米零价铁去除水中重金属离子的研究进展

重金属离子危害严重.本文综述了近几年纳米零价铁去除水中重金属离子的研究,总结了纳米零价铁去除水中重金属离子的机理,主要包括:纳米零价铁的表面吸附-配合、还原、吸附-还原,并对纳米零价铁在这一领域的应用进行了展望.     

Organic Ion Exchangers. Synthesis and Their Behaviour in the Retention of Some Metal Ions

Summary: Three pyridine strong base anion exchangers as beads were obtained by quaternization reactions of a 4-vinylpyridine : 8% divinylbenzene copolymer of gel type. These resins possess methyl / ethyl / butyl radicals as substituents on N⁺ atoms and have exchange capacities of 4.80 mEq/g and 2.10 mEq/mL. For pyridine strong base anion exchangers, the behaviours in the retention processes of Cr(VI) as oxyanions and Ga(III) as [GaCl₄]⁻ complex anion were evaluated with the bath method. All the resins exhibited retention properties, but the retained amounts of the metal cations are different as a function of the alkyl length as substituent on N⁺ atoms and the complex anion nature. Thus, Cr(VI) oxyanions are best retained by the resin with  CH₃ as substituent on N⁺ atoms while [GaCl₄]⁻ complex anion by the resin with  C₄H₉ as substituent on N⁺ atoms. By aminolysis reaction of an ethylacrylate : acrylonitrile : divinylbenzene copolymer as beads of macroporous type with NH₂OH · HCl in the presence of C₂H₅OH a new chelating ion exchanger was performed which contains both amidoxime and hydroxamic acid functional groups. This ion exchanger has the retention property for different metal cations but its retention capacities values are strongly dependent of the nature of metal cation and the counterion as well as pH of the solution. Thus, in the static conditions Zn(II) cation with NOequation/tex2gif-stack-1.gif anion as counterion is retained with the best result at pH = 5. As an example, for the aqueous metal cation solution of 10⁻² M concentration for Zn(NO₃)₂ the resin possess at equilibrium a retention capacity of 6.70 mmol Zn/g dry resin and for Cu(II) from Cu(NO₃)₂ solution of same concentration, the retention capacity is 0.22 mmol Cu/g dry resin and Fe(III) from Fe(NO₃)₃ solution is not retained.     

Extraction Mechanism of Metal Ion from Aqueous Solution to the Hydrophobic Ionic Liquid, 1-Butyl-3-methylimidazolium Nonafluorobutanesulfonate

Summary. We studied the extraction behavior of metal ionic species in aqueous solutions into the hydrophobic ionic liquid, 1-butyl-3-methylimidazolium nonafluorobutanesulfonate ([bmi][NfO]). The extraction ratios (E/%) of Li(I), Na(I), Cs(I), Ca(II), Sr(II), and La(III) species were found to be 39, 24, 5.0, 81, 79, and 98. This result is similar to the phenomena that the metal ions with larger charge are more easily adsorbed onto cation exchange resins. In order to examine the extraction mechanism, we studied the extraction behavior of La(III) species from the aqueous to the [bmi][NfO] phase. As a result, it was found that the E values of La(III) decrease remarkably with an increase in concentrations of HNO₃ (0–1 M) in the aqueous phase and that the amount of La(III) transferred into [bmi][NfO] phase increases linearly with an increase in the amount of [bmi] transferred into the aqueous phase. Furthermore, we investigated the extraction behavior of La(III) species using 1-pentyl- and 1-hexyl-3-methylimidazolium nonafluorobutansulfonate ([pmi][NfO], [hmi][NfO]), which are more hydrophobic than [bmi][NfO], and found out that the E values of La(III) decrease in order of [bmi][NfO] > [pmi][NfO] > [hmi][NfO]. From these results, it was proposed that the extraction of metal ionic species from the aqueous to the [bmi][NfO], [pmi][NfO], or [hmi][NfO] phase is mainly ascribed to the cation exchanges between two phases.     

功能化碳质材料的制备及其对水中重金属的去除

重金属污染是目前最为严峻的环境问题之一,我国的重金属污染问题尤为突出。活性炭、纳米碳管和石墨烯等环境友好型碳质材料由于其比表面积大,吸附能力强等优点而被应用于水中重金属的去除,而进行官能团功能化改性后其吸附效果可以明显提高。本文重点阐述了活性炭、纳米碳管、石墨烯及生物质炭等碳质材料的巯基化(-SH)、氨基化(-NH₂)等功能化改性方法及其应用,考察了功能化碳质复合材料对水中重金属离子的去除效果和影响因素,最后展望了功能化碳质复合材料对水中重金属污染物去除研究的发展方向。     

基于荧光共轭聚合物的金属离子检测

以聚乙炔、聚芴、聚噻吩、聚苯撑为代表的荧光共轭聚合物,由于具有独特的光学性能、自组装性能和结构与性能的可调控性,可作为优异的光学传感材料。利用其具有较高摩尔消光系数和荧光量子产率的特点,可设计具有较高灵敏度和选择性的传感器,这已成为生物传感领域的研究热点。以荧光共轭聚合物为基础的金属离子检测,最初是以非水溶性的共轭聚合物为主,通过金属离子与聚合物链上特定基团(如吡啶、冠醚)的结合引起的聚合物荧光性质的变化可实现对某些离子的检测。在共轭聚合物主链上引入亲水性侧链,可大大增强共轭聚合物的水溶性,为金属离子的生物传感检测提供了新的思路,例如可引入能与金属离子结合的生物分子(如DNA、糖基等)来设计传感策略,进一步提高检测的特异性和灵敏度。本文综述了近年来以非水溶性和水溶性荧光共轭聚合物为传感材料,对具有重要生物学意义的重金属离子(Hg²⁺、Pb²⁺)、过渡金属离子(Cu²⁺、Eu³⁺、Ni²⁺、Fe³⁺、Fe²⁺、Ru³⁺、Ag⁺)和碱金属离子(K⁺、Na⁺、Li⁺)进行高灵敏度检测方面的研究进展,并对该领域的发展前景进行了展望。     

甲基异丁酮碘萃合物-水界面上的循环伏安法间接测定水溶液中氧化性金属离子

利用甲基异丁酮(MIBK)作为萃取剂,等体积法将水中的碘萃取到有机相中,微量进样器将20～40μL有机溶液注入玻璃微管中,使它处于界面上。利用经典的三电极系统研究该有机相在液/液界面的伏安特性。实验结果表明,该过程是一个受扩散控制的不可逆过程。有机相中碘的含量和峰电流大小在一定范围内成正比。利用这一特性可以间接测定水溶液中具有氧化性的金属离子(如Cr2O72-、Cu2 等)的含量,检出限为10-5mol/L。     

Kinetic and Thermodynamic Studies for the Removal of Nickel Ions from an Aqueous Solution by Adsorption Technique

The kinetics and dynamics of nickel ions adsorption on activated carbon and bentonite were studied. The influence of parameters (pH, amount of adsorbent, adsorbate concentration, solution volume, rotation speed, and temperature) were investigated. Kinetic models of pseudo-first, pseudo-second and Weber-Morris models were applied. The data was better reported by the pseudo-second order model. Freundlich, Langmuir, and D-R models were utilized for the analysis of adsorption equilibrium. Evaluation of thermodynamic parameters reveal that adsorption is spontaneous and endothermic in nature. From the experimental data, it was concluded that bentonite has more efficiency for the adsorption of nickel ions than activated carbon.     

Oxidized Biomass and Its Usage as Adsorbent for Removal of Heavy Metal Ions from Aqueous Solutions

Nowadays, very coarse wool fibers are considered waste biomass and are discarded at random or burned. Therefore, it is of actual interest to valorize coarse wool fibers as utile products. In this sense, we report herein an environmentally-friendly process for the preparation of a new material based on oxidized wool fibers and designed for efficient adsorption of heavy metals from wastewater. The morphology and the structure of the obtained product were characterized by scanning electron microscopy (SEM) coupled with an X-ray energy-dispersive module (EDX) and by Fourier-transform infrared spectroscopy (FTIR). Likewise, the performances of the oxidized wool fibers for the adsorption of heavy metal cations (Cu²⁺, Cd²⁺, Pb²⁺) from aqueous solutions were tested. The adsorption kinetics data were analyzed by applying the pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models. The equilibrium of the adsorption process was investigated by using the Freundlich and Langmuir isotherm models. According to the Langmuir isotherms registered at 300 K, the maximum adsorption capacities of the oxidized wool were found to increase from Cu²⁺ (9.41 mg/g) and Cd²⁺ (10.42 mg/g) to Pb²⁺ (30.71 mg/g). Consequently, the removal efficiency of metal ions was found to vary in the range of 96.8–99.7%. The thermodynamic parameters (e.g., enthalpy, entropy, and Gibbs free energy) were calculated and discussed.     

离子色谱法分析金属离子的研究进展

综述了离子色谱法(IC)分析金属离子的研究进展,对目前应用于分析金属离子的阳离子交换IC、阴离子交换IC和螯合离子色谱进行了评述。阳离子交换IC是IC分析金属离子的主要形式,固定相为强酸(磺酸)型阳离子交换剂和弱酸(羧酸)型阳离子交换剂,结合适当的检测方法,阳离子交换IC可以测定碱金属、碱土金属、过渡金属、稀土离子、铵离子及低相对分子质量的有机胺类分子等。阴离子交换IC可以分析碱土金属、过渡金属、稀土离子等,对金属离子的分析具有更好的选择性,并可以实现金属离子和无机阴离子的同时测定。螯合离子色谱可以对复杂基体中的痕量金属离子进行测定。引用文献125篇。     

辐射诱导合成水凝胶及其处理重金属废水的研究进展*

水凝胶是一种经适度交联而具有三维网络结构的新型功能高分子材料。制备水凝胶因操作简单、无须添加交联剂和引发剂等优点而受到关注。传统的处理重金属废水的方法或成本较高,或效率低,利用水凝胶处理重金属废水成为一种新的颇具潜力的方法。本文综述了辐射法制备水凝胶及其在重金属吸附去除方面的研究进展包括材料的制备、改性、去除重金属性能等方面的研究进展,并指出了水凝胶去除重金属的发展前景和今后的研究方向。     

离子色谱法测定中药女贞子浸煮液中的碱金属和碱土金属

用离子色谱法测定了中药女贞子水浸煮液中K+、Na+、Ca2+、Mg2+的含量,色谱柱为IonPAC CS 12A(4 mm×250 mm)阳离子交换柱,淋洗液为11.0 mmol/L的硫酸溶液,流速1.00mL/min,电导检测器检测。结果表明,4种离子的检出限分别为:Na+0.021 mg/L,K+0.020 mg/L、Mg2+0.015 mg/L,Ca2+0.100 mg/L,相对标准偏差在0.72%~3.92%之间,回收率为98.3%~103.1%。结论:该法操作简便、快速,准确,为测定其它中药中Na+、K+、Mg2+、Ca2+的含量提供了一种有效的方法。     

The Use of Encoded Structural Data to Predict the Liquid Chromatographic Retention Behavior of Tetradentate Metal Complexes

Abstract

Retention data for tetradentate metal complexes of copper and nickel are reported for microparticulate silica and reversed phase columns. An attempt is made to relate structure and stability constant data to the retention volume by means of multiple linear regression. The results indicate that if the structure is encoded by means of dummy variables it may be possible to predict retention volumes of metal complexes. There is not a strong correlation between the value of the stability constants for the metal diamine and metal ketone complexes and the retention volume.