Sonochemical preparation of composite nanoparticles of Au/gamma-Fe2O3 and magnetic separation of glutathione

We prepared Au/gamma-Fe2O3 composite nanoparticles by sonochemically reducing Au(III) ions employing no stabilizer in the aqueous solution to form stable Au nanoparticles and allowing them to attach onto the surface of gamma-Fe2O3 particles with an average size of 21 nm. Size of the formed Au nanoparticle depended on the initial concentration of Au(III) ions. The number of the Au nanoparticles, supported on each gamma-Fe2O3 particle was controlled by changing the relative amounts of Au(III) ions and gamma-Fe2O3 particles. The composite nanoparticles exhibited a high affinity with glutathione, a tripeptide with mercapto group so that separation and manipulation of glutathione in aqueous solutions could be performed by application of external magnetic field. Because the surfaces of the Au nanoparticles were not shielded by any stabilizers, or naked, sonochemically prepared Au/gamma-Fe2O3 composite nanoparticles seemed to show stronger affinity to the glutathione than those by the radiochemical method.     

Adsorption of Zn(II) and Cd(II) ions onto magnesium and activated carbon composite in aqueous solution

Magnesium and coconuts shell activated carbon composite was prepared to selectively remove heavy metals ions in aqueous solution. Zinc(II) and cadmium(II) ions were used to clarify the adsorption capacity of the composite in comparison with no magnesium containing activated carbon. Influence of the initial heavy metal concentration, time course and solution temperature on the adsorption amounts were examined for the two adsorbents, and surface chemistry of the adsorbents was also characterized using Boehm titration. The magnesium composite adsorbed greater amount of Zn(II) and Cd(II) ions than the no magnesium counterpart. The adsorption amount of Cd(II) was not influenced with rise in solution temperature for the composite, whereas decrease in adsorption was observed for the counterpart. The loaded magnesium was estimated to be combined with carbon surface via oxygen bridge. Cadmium(II) was adsorbed onto the composite surface by ion exchange process with releasing equivalent amount of Mg(II) from the carbon surface, while Zn(II) would adsorb onto the composite by not only the ion exchange, but also the electrostatic interaction with the Cπ electrons on the graphite surface from the experimental results.     

Vermiculite as an exchanger for copper(II) and Cr(III) ions,kinetic studies

The adsorption of Cu(II) and Cr(III) ions by pure clay mineral, vermiculite, was examined in aqueous solution with respect to the adsorbent dose, initial metal ion concentration, pH, and contact time. The studies showed that vermiculite can be used as an adsorbent material for the moderate removal of Cr(III) and Cu(II) from aqueous solutions. Lagergren first-order, pseudo-second-order, and intraparticle diffusion models were used to describe the kinetic data. The kinetics of adsorption indicates that the process fitted well the intraparticle diffusion model.     

Evaluation of Cyanex 923-coated magnetic particles for the extraction and separation of lanthanides and actinides from nuclear waste streams

In the magnetically assisted chemical separation (MACS) process, tiny ferromagnetic particles coated with solvent extractant are used to selectively separate radionuclides and hazardous metals from aqueous waste streams. The contaminant-loaded particles are then recovered from the waste solutions using a magnetic field. The contaminants attached to the magnetic particles are subsequently removed using a small volume of stripping agent. In the present study, Cyanex 923 (trialkylphosphine oxide) coated magnetic particles (cross-linked polyacrylamide and acrylic acid entrapping charcoal and iron oxide, 1:1:1, particle size=1–60 μm) are being evaluated for the possible application in the extraction and separation of lanthanides and actinides from nuclear waste streams. The uptake behaviour of Th(IV), U(VI), Am(III) and Eu(III) from nitric acid solutions was investigated by batch studies. The effects of sorption kinetics, extractant and nitric acid concentrations on the uptake behaviour of metal ions were systematically studied. The influence of fission products (Cs(I), Sr(II)) and interfering ions including Fe(III), Cr(VI), Mg(II), Mn(II), and Al(III) were investigated. The recycling capacity of the extractant-coated magnetic particles was also evaluated.     

Neutron bound beta-decay: BOB

Frozen solution samples were made from gold chloride and KAu(CN)₂ solvated with TBP/xylene. The ¹⁹⁷Au M?ssbauer parameters were similar to those same species as frozen solutions or adsorbed onto activated carbon. Solvated samples from EuO dissolved in HCl or H₂SO₄ and frozen gave characteristic Eu(III) spectra. All the spectra were consistent with bonding to the TBP being through hydronium ions or water molecules.     

A Highly Selective Turn-On Fluorescent Chemosensor for Zinc Ion in Aqueous Media

In the paper, a novel rhodamine6G based fluorescent chemosensor bearing 3-carbaldehyde chromone was designed and synthesized. According to the fluorescence behavior toward several metal ions, it showed highly selectivity and sensitivity to Zn(II) over other commonly coexistent metal ions (Cu(II), Cd(II), Hg(II), Mg(II), K(I), Pb(II), Fe(III) and Cr(III)) in aqueous environment (pH?=?7.4). Meanwhile the binding constant between Zn(II) and chemosensor achieved 6.21?×?10¹¹ M^?1 in aqueous media. Moreover, according to the Job plot, 1:1 stoichiometry between Zn(II) and sensor was deduced in aqueous media (pH?=?7.4). The good selectivity and sensitivity in aqueous media effectively enhanced the application value of the fluorescent chemosensor for Zn(II).     

Size controlled gold nanoparticle formation by <Emphasis Type="Italic">Avena sativa</Emphasis> biomass: use of plants in nanobiotechnology

Oat (Avena sativa) biomass was studied as an alternative to recover Au(III) ions from aqueous solutions and for its capacity to reduce Au(III) to Au(0) forming Au nanoparticles. To study the binding trend of Au(III) to oat and the possible formation of Au nanoparticles, the biomass and a solution of Au(III) were reacted for a period of 1 h at pH values ranging from 2 to 6. The results demonstrated that Au(III) ions were bound to oat biomass in a pH-dependent manner, with the highest adsorption (about 80%) at pH 3. HRTEM studies showed that oat biomass reacted with Au(III) ions formed Au nanoparticles of fcc tetrahedral, decahedral, hexagonal, icosahedral multitwinned, irregular, and rod shape. To our knowledge, this is the second report about the production of nanorods as a product of the reaction of a Au(III) solution with a biological material. These studies also showed that the pH of the reaction influenced the nanoparticle size. The smaller nanoparticles and the higher occurrence of these were observed at pH values of 3 and 4, whereas the larger nanoparticles were observed at pH 2.     

One‐pot oxidation of aromatic and cyclic hydrocarbons using the Au (III) and Pd (II) catalyst under microwave irradiation

We report here in highly efficient one‐pot catalytic system which utilizes in situ generated sodium ferrate for the oxidation of aromatic and cyclic hydrocarbons in the presence of Au (III) and Pd (II) metal ions catalyst under ecofriendly green synthetic method. Results of these studies revealed that Au (III) catalytic system gave higher yield as compared with Pd (II) catalytic system because of the higher electrode potential of Au(III) than Pd(II). All compounds were characterized by infrared and NMR spectral analysis. Copyright © 2016 John Wiley & Sons, Ltd.     

pH effect on the physicochemical characteristics and efficiency of electroflotation extraction of low-soluble iron subgroup metal compounds from aqueous solutions

This paper reports on our study of the pH effect of solutions on the average hydrodynamic diameter (d_av) of the particles of the disperse phase and the electrokinetic potential (ζ) of the particles of low-soluble iron subgroup metals compounds using Fe(II, III), Ni(II), and Co(II) compounds as an example. The pH effect of solutions on the efficiency of the electroflotation extraction of metal ions from aqueous solutions containing these ions in individual form or in mixture was studied. The efficiency of the electroflotation extraction of the low-soluble compounds of iron subgroup metals is directly related to the particle size and electrokinetic potential of the particles, which depend on рН. The maximum degree of particle extraction α reached 97–99% at рН values characterized by the maximum hydrodynamic diameter of particles (over 20 μm for Fe(II) and Co(II) compounds and over 50 μm for Fe(III) and Ni(II) compounds) at ζ potentials of up to–10 mV for systems approximated to real wastewater. In the case of the extraction of the disperse phase of the Fe(III)–Ni(II)–Co(II) multicomponent system, the synergic effect was observed: the coextraction of metals was more complete and effective, which may be due to suppressed negative charge. In the range of рН 10–11, the degree of extraction of the Fe(III) disperse phase did not exceed 74%; in the ternary system, it reached 94%.     

Synthesis and Properties of Tannic Acid-Based Hydrogels

Hydrogels were synthesized by using tannic acid (TA) as a chemical cross-linker for the copolymer of allylglycidyl ether and acrylamide. The swelling ratio of the hydrogels increased with increasing amount of TA and decreased with increasing amounts of allylglycidyl ether. The hydrogels exhibited pH sensitivity; the swelling ratio increased with pH. Adsorption experiments of the hydrogel for Cu (II) ions suggested that the hydrogels can be used as an adsorbent for removal of Cu (II) heavy metal ions from dilute aqueous solutions.     

Tween-80-(NH4)2SO4-XO体系中铜、镧、铀、铈光谱及萃取性能研究

利用二甲酚橙作萃取剂 ,在吐温 80 (NH4 ) 2 SO4 二甲酚橙 (XO)固 液萃取体系中 ,研究了萃取相 (固相 )中金属离子络合物吸收光谱 ,与XO光谱比较 ,Cu(Ⅱ ) ,U(Ⅵ ) ,Ce(Ⅳ )离子吸光度增大 ,最大吸收波长红移 2 0～ 30nm ;La(Ⅲ )离子几乎未变。同时探讨了该体系中不同酸度、不同盐用量、不同萃取剂用量、不同类型表面活性剂 ,对Cu(Ⅱ ) ,La(Ⅲ ) ,U(Ⅵ ) ,Ce(Ⅳ )离子的萃取率的影响 ,在pH 6 0的酸度下 ,实现了La(Ⅲ )与U(Ⅵ )之间的萃取分离。     

Instantaneous integration of magnetite nanoparticles on graphene oxide assisted by ultrasound for efficient heavy metal ion retrieval

We fabricated a magnetite nanoparticle-graphene oxide (GO) hybrid via a non-chemical and one-step process assisted by ultrasound in an aqueous solution where the nanoparticle attached to the hydrophobic region on graphite oxide (multi-layered GO) which, at the same time, was exfoliated. Unlike chemical methods such as precipitation, oxygen-containing functional groups on GO have not been consumed or reduced during the hybridization, leading that this hybrid exhibited good water solubility and high adsorption capacity for heavy metal ions such as Pb(II) and Au(III). After the adsorption, the hybrid was instantly collected using a magnet. This method can be useful for hybridizing various nanoparticles with GO.     

Solvent extraction of Am(III) and Eu(III) from nitrate solution using synergistic mixtures of N-tridentate heterocycles and chlorinated cobalt dicarbollide

The separation by solvent extraction of ²⁴¹Am(III) from ¹⁵²Eu(III), in 1 M NaNO₃ weakly acidic (pH 4) aqueous solutions, into dilute (ca. 10⁻² M) solutions of triazinylbipyridine derivatives (diethylhemi-BTP or di(benzyloxyphenyl)hemi-BTP) and chlorinated cobalt dicarbollide (COSAN) in 1-octanol or nitrobenzene has been studied. The N-tridentate heterocyclic ligands, which are selective for Am(III) over Eu(III), secured efficient separation of the two metal ions, while COSAN, strongly hydrophobic and fully dissociated in polar diluents, enhanced the extraction of the metal ions by ion-pair formation. Molecular interactions between the two co-extractants, observed at higher concentrations, led to the precipitation of their 1: 1 molecular adduct. In spite of that, efficient separations of Am and Eu ions were attained, with high separation factors, SF_Am/Eu of 40 and even 60, provided the concentration of hemi-BTP was significantly greater than that of COSAN. Excess COSAN concentrations caused an antagonistic effect, decreasing both the distribution ratio of the metal ions and their separation factor.     

Uptake of Europium(III) from Water using Magnetite Nanoparticles

It is demonstrated that colloidal magnetite nanoparticles can be used as nanosorbents for lanthanide ions dissolved in water. In particular, a series of experiments are performed for the removal of Eu(III) in distinct analytical conditions and by applying an external magnet to collect the sorbents previously dispersed in water samples. Furthermore, strategies for surface chemistry functionalization are also investigated, aiming to investigate the effect of this parameter on the removal capacity of the Fe₃O₄ nanoparticles. The supernatant solutions are monitored for the remaining amount of Eu(III) by fluorescence emission measurements in the presence of 2,6‐pyridinedicarboxylic acid as a sensitizer. The results demonstrate that neat Fe₃O₄ nanoparticles are capable of capturing lanthanide ions (III) from aqueous solutions (pH 7), without need of surface modification, and for subsequent removal by magnetic separation. During the removal, efficiency is increased after modifying the particles' surfaces with silica and 3‐aminopropyltrimethoxysilane; in alkaline medium (pH 10), there is complete removal regardless the type of nanosorbent used. This has been explained by the formation of insoluble Eu(III) species that adsorb strongly to the nanosorbents surfaces allowing their subsequent magnetic separation.     

偕胺肟纤维与Fe(Ⅲ),Co(Ⅱ),Ni(Ⅱ),Cd(Ⅱ),Hg(Ⅱ)配合物的红外光谱研究

用聚丙烯腈纤维 (PAN)改性制备的偕胺肟纤维 (AOCF)分别与三氯化铁、氯化钴、氯化镍、氯化镉和氯化汞在酸性介质中反应 ,制备偕胺肟 铁 (Ⅲ )、偕胺肟 钴 (Ⅱ )、偕胺肟 镍 (Ⅱ )、偕胺肟 镉 (Ⅱ )和偕胺肟 汞 (Ⅱ ) 5种偕胺肟 重金属配合物 (用通式M AOCF表示 )。用红外分光光度计分别对偕胺肟纤维和 5种配合物在 4 0 0 0～ 4 0 0cm- 1 范围进行傅里叶变换红外吸收 ,对各M AOCF的FTIR主要吸收峰做了经验归属 ,并将各M AOCF的特征吸收峰与AOCF的相应吸收峰作对比分析 ,结果表明 :配合物中C—N ,CN ,N—O等键的吸收峰位置均向高波数方向移动 ,且峰的强度增加。说明纤维材料中的偕胺肟基团与重金属离子在酸性介质中进行了配位反应 ,偕胺肟基团与重金属离子之间形成了配位键。     

Synthesis of gold and platinum nanoparticles using tetraaniline as reducing and phase transfer agent—A brief study and their role in the electrocatalytic oxidation of glucose

A one-pot synthesis of Au and Pt nanoparticles by the spontaneous reduction of chloroaurate and chloroplatinate ions using tetraaniline molecules has been elucidated. The importance of this work is that tetraaniline acts as a multifunctional molecule that accomplishes the complexation of aqueous chloroaurate and chloroplatinate ions by phase transferring them to organic medium and their subsequent reduction to yield Au and Pt nanoparticles in organic phase. The metal reduction is followed by polymerization of the amine to yield polyaniline, which subsequently caps the Au and Pt nanoparticles. Various analytical techniques have been used for probing the process of reduction of auric and platinic metal precursors like UV-vis, X-ray diffractogram (XRD) and transmission electron micrographic (TEM) analysis. Such prepared nanoparticles are utilized for the fabrication of novel modified electrodes towards the electrocatalytic oxidation of glucose.     

双水相体系中Cu(Ⅱ),La(Ⅲ),U(Ⅵ),Ce(Ⅳ)光谱行为及萃取分离

利用聚乙二醇2000(PEG)-(NH)2SO4-萃取剂(铜试剂)双水相体系,采用液-液萃取的方法,研究了PEG相、单纯水相中金属离子络合物及萃取剂的光谱行为,探讨了金属离子络合物在PEG相中存在形态及萃取机理。同时实验了在不同酸度,不同盐用量,不同萃取剂用量,以及在不同表面活性剂的影响下,铜、镧、铀、铈的萃取率,通过控制一定条件,实现了Cu(Ⅱ)与La(Ⅲ),Cu(Ⅱ)与Ce(Ⅳ)之间的定量萃取分离。     

Study of Infrared and Electronic Spectra Of N-Exadecyl-8-hydroxy-2-quinolinecarboxamide Complexes

The infrared and electronic spectra of twelve amphiphilic complexes of N-hexadecyl-8-hydroxy-2-quinoline carboxamide (HL) have been investigated. In IR spectra a linear relationship between the v (C-O) frequency in C-O-M bond of the complexes and the relative atomic weight of the central metal ions and a linear relationship between the v (C-O) frequency and the ionization potential of the central metal (M →M²⁺(g)+2e) were obtained. These complexes appeared to fall into two groups. One is the complexes of closed-shell metal ions such as Ca(II), Mg(II), Zn(II), Cd(II), Al(III), La(III) and Gd(III) ion, the other is the complexes of transitional metal ions such as Mn(II), Co(II), Ni(II) and Cu(II) ion. All these complexes can form stable monolayer and can be deposited as uniform LB films.     

复合氧化物纳米粉体颜料的制备和表征

印染行业重点技术发展的目标之一就是研制开发高效、环保、安全的新型染化料,为了解决纺织印染中的废水污染问题,发展无水印染新技术,是一个引起人们广泛关注的新研究方向。我们受红宝石,蓝宝石结构特征的启发,尝试采用均相沉淀法合成以α-氧化铝为基质,通过少量掺杂呈色离子的复合氧化物颜料。实验中,将结晶氯化铝和一定比例的发色离子氯化物混合,用适量的蒸馏水溶解,再溶入尿素和聚乙烯吡咯烷酮,超声振荡均匀,将上述液体加热回流,煅烧反应后的产物,得到纳米无机颜料。通过XRD测定样品的晶型和纯度,确定新型颜料的主体成分是α-氧化铝,用紫外可见光谱仪测试样品的漫反射光谱,发现掺杂离子周围的配位环境变化导致吸收峰谱带发生变化。在此基础上用分光密度仪表征样品的色度,应用SEM进行微观形貌分析,样品粒径范围在200～300nm。将制成的复合氧化物颜料用饱和盐酸浸泡,对浸出液进行ICP测试,发现掺杂离子溶出量非常少,说明新型颜料具有良好的化学稳定性。上述结果说明,这类新型无机纳米粉体颜料各种耐性良好、无毒害,可以满足熔体纺丝要求,有望在无水印染方面得到应用。     

X‐ray absorption spectroscopic study on gold particles formed on titania and alumina

X‐ray absorption near‐edge structure (XANES) measurements near the Au L₃ edge were made on Au(III) complex ions adsorbed on titania and alumina without a specific reducing agent. Compared with the XANES spectrum of a pure gold foil, the gold adsorbed on titania and alumina was found to be reduced to Au(0). The XANES method could obtain spectra of gold particles less than 1 nm in diameter, although a UV–visible absorption spectrum was difficult to observe with such samples. Copyright © 2003 John Wiley & Sons, Ltd.