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1.
A cost-efficient kaolinite-cellulose/cobalt oxide green nanocomposite (Kao-Cel/Co3O4 NC) was successfully synthesized, and utilized as a promising material for removing Pb2+ and Cd2+ from aqueous solution. The fabricated nanocomposite has been characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy-energy dispersive X-ray, high-resolution transmission electron microscopy, and Brunauer-Emmett-Teller analysis. The batch methodology was exploited for optimization of process parameters and the optimized conditions were found to be adsorbent dosage (2.0 g/L), extraction time (50 min), initial concentration (60 mg/L), and initial solution pH (6). Kao-Cel/Co3O4 NC displayed excellent adsorption properties and achieved maximum saturation capacity (Qm) of 293.68 mg Pb2+/g and 267.85 mg Cd2+/g, with an equilibration time of 50 min at 323 K. The Langmuir model best expressed the isotherm data recommending the adsorption onto energetically homogeneous NC surface, while the compatibility of kinetics data with pseudo-second-order model revealed the dependency of adsorption rate on adsorption capacity, and probable involvement of chemisorption in the rate-controlling step. Electrostatic interaction and ion exchange mechanism were responsible for the uptake of Pb2+ and Cd2+ by Kao-Cel/Co3O4 NC as demonstrated by Fourier transform infrared spectroscopy and pH studies. Thermodynamic parameters confirmed the physical, spontaneous, and endothermic sequestration processes. Real water investigation specified that the present adsorbent could be effectively used for liquid phase decontamination of Pb2+ and Cd2+. The nanocomposite exhibited high reusability, which could be utilized efficiently for five runs with sustainable results. In summary, this study portrayed the present nanocomposite as an emerging material for the adsorption of heavy metal ions particularly Pb2+ and Cd2+.  相似文献   

2.
In the present study, application of Fe3O4 magnetic nanoparticles (MNPs) coated with diethyldithiocarbamate as a solid-phase sorbent for extraction of trace amounts of cadmium (Cd2+) and nickel (Ni2+) ions by the aid of ultrasound was investigated. The analytes were determined by inductively coupled plasma-optical emission spectroscopy. Fe3O4 MNPs were prepared by solvothermal method and characterized with dynamic light scattering, scanning electron microscope and X-ray diffraction. Response surface methodology was used for optimization of the extraction process and modeling the data. The optimal conditions obtained were as follows: chelating agent, 1.2 g L?1; pH, 6.13; sonication time, 13 min and Fe3O4 MNPs, 10.3 mg. The calibration curves were linear over the concentration range of 1–1,000 μg L?1 for Cd2+ and 2.5–1,000 for Ni2+ with the determination coefficients (R 2) of 0.9997 and 0.9995, respectively. The limits of detection were 0.27 μg L?1 for Cd2+ and 0.76 μg L?1 for Ni2+. The relative standard deviations (n = 7, C = 200 μg L?1) for determination of Cd2+ and Ni2+ were 2.0 and 2.7 %, respectively. The relative recoveries of the analytes from tap, river and lagoon waters and rice samples at the spiking level of 10 μg L?1 were obtained in the range of 95–105 %.  相似文献   

3.
The solubility of cadmium in PbTe was determined using microhardness and hydrostatic density measurements and by electron microscopy and electron probe microanalysis. All these methods indicate that the existence region of Pb1 − x Cd x Te solid solutions (ss) extends to x = 0.08 at 670°C. As the cadmium concentration of the solid solution increases, microhardness shifts up, whereas density shifts down.  相似文献   

4.
In this paper, x (=2, 5, 7 and 10mol%) Co2+-doped Fe2O3 (xCo:Fe2O3) nanoparticles with enhanced photocatalytic activity have been reported. xCo:Fe2O3 nanoparticles were successfully prepared by co-precipitation followed thermal decomposition method. The structural, optical and morphological properties of the prepared samples were studied by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), diffuse reflectance (DR) UV–visible absorption spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The obtained results revealed that Co2+ ions were well doped within the lattices of Fe2O3. Also, Co2+ ions suppress the formation of the most stable α- Fe2O3 and stabilize less stable γ-Fe2O3 at 450 °C. The photocatalytic activity of xCo:Fe2O3 was examined by using pararosaniline (PR) dye. It was found that photocatalytic degradation of PR depends on dopant concentration (Co2+ ions). Relatively, the highest photocatalytic activity was observed for 5%Co:Fe2O3 nanoparticles. The plausible photocatalytic degradation pathway of PR at xCo:Fe2O3 surface has also been proposed.  相似文献   

5.
The coordination behaviour of the redox-active polyazacycloalkane L1 against the toxic heavy-metal ions Cd2+, Pb2+, and Hg2+ was studied in THF/H2O 70 : 30 (containing 0.1 mol⋅dm−3 of (Bu4N)ClO4). The crystal and molecular structure of the cadmium complex [Cd(L1)(NO3)2] ( 1 ) was determined by X-ray single-crystal analysis. The cadmium ion is in a 4+2 surrounding with the ligand L1 acting as tetradentate and the apical positions occupied by the O-atoms of the nitrate anions. An electrochemical study reveals that L1 shows a selective electrochemical response against Hg2+ over Cd2+ and Pb2+.  相似文献   

6.
Knudsen effusion mass spectrometry has been applied to two identical alumina cells inside a revolving molybdenum cylinder. The one cell was filled with cadmium ferrite and the other with cadmium oxide, and the ionic current intensities of Cd+ and O2+ were measured above both samples. The ratio between the intensities above the ferrite and above the oxide was found to be approx. 0.6, for both Cd+ and O2+. From this ratio and from calorimetric data the Gibbs energy of the reaction CdO + Fe2O3 → CdFe2O4 could be derived. The endothermic ferrite is stable above 677 K. Its normal enthalpy, H°298 is - 1 065 kJ/mol, and its normal entropy, S°298 is 168 J/K mol. The non-stoichiometry of CdO is discussed.  相似文献   

7.
A novel cadmium(II) complex with N-(2-acetic acid)salicyloyl hydrazone (C9H8N2O4, H3L) and imidazole (Im) was prepared and characterized. The crystal structures of ligand H3L and cadmium(II) complex were determined by X-ray single-crystal diffractometry. The complex consists of three binuclear neutral unattached units. One of Cd2+ is six-coordinated by the carboxylic O atom, acylic O atom, and azomethinic N atom of one ligand H3L (HL2− form), carboxylic O atom from the other ligand H3L by the μ2-bridging form and N atoms from two imidazoles, but the other five Cd2+ ions all are seven-coordinated more than an O atom from coordinated water molecule compared with six-coordinated Cd2+. HL2− acts as tridentate ligand forming two stable five-numbered rings and sharing one side in the keto form for each ligand, and the carboxyl groups of two HL2− ligands are coordinated via the μ2-bridging form. The coordination polyhedron around Cd2+ was described as a octahedron or pentagonal bipyramidal. The inter- and intramolecular hydrogen bonds resulted in a three- dimensional network and provided extrastability for the structure. The complex exhibits good fluorescence properties. The complex was also searched for the interaction with CT-DNA by electronic absorption titration and emission titration. The results show that the complex is bound to calf thymus DNA mainly by intercalation.  相似文献   

8.
Uniform and well-defined Lu2O3 and Lu2O3:Eu3+ microarchitectures have been successfully synthesized via a green and facile ionic liquid-based hydrothermal method followed by a subsequent calcination process. Novel 3D micro-rodbundles and 1D microrods of Lu2O3 and Lu2O3:Eu3+ were controllably obtained through this method. X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and photoluminescence spectra were used to characterize the micromaterials. The proposed formation mechanisms have been investigated on the basis of a series of SEM studies of the products obtained at different hydrothermal durations. The results indicated that hydrothermal temperature and the ionic liquid-tetrabutylammonium hydroxide were two key factors for the formation as well as the morphology control of the Lu2O3 and Lu2O3:Eu3+ microarchitectures.  相似文献   

9.
Bifunctional magneto-optical nanocomposites with Fe3O4 nanoparticles as a core and erbium and lithium codoped gadolinium (Gd2O3:Er3+, Li+) as the shell were synthesized successfully using a simple urea homogeneous precipitation method. The fabricated Fe3O4@Gd2O3:Er3+, Li+ particles were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy and quantum design vibrating sample magnetometry. The upconversion emission intensity was enhanced significantly comparing to that without Li+ ions. These bifunctional composites are expected to be potentially applied for drug delivery, cell separation and bioimaging.  相似文献   

10.
The formation of cadmium sulfide nanoparticles upon UV irradiation of aqueous solutions of cadmium thiosulfates was established on the basis of spectroscopic and macroscopic data. The yield and size of the cadmium sulfide nanoparticles depend on the ratio of cadmium to thiosulfate ions in solution, the concentration of the solution, and the irradiation duration. The cadmium sulfide nanoparticles with a diameter of 4 nm were obtained by the photolysis of solutions with a concentration of 10−3 mol L−1 at the ratio S2O3 2−: Cd2+ = 2: 1.  相似文献   

11.
We propose a simple, fast and sensitive colorimetric method for the determination of Cd2+ using 1,13-bis(8-quinolyl)-1,4,7,10,13-pentaoxatridecane modified silver nanoparticles. The addition of Cd2+ causes the aggregation of AgNPs, while other ions do not have such effect. As a result, the color of the solution changes from yellow to red which can be detected using naked eye or by UV–Vis spectroscopy. The aggregation of the AgNPs is confirmed by UV–Vis and transmission electron microscopy. Limit of detection is found to be 0.016 µM for Cd2+ ions. A linear calibration plot is correlated to the concentration of cadmium ion in the 0.5–6.0 μM range with the naked-eye detection limit of 2.0 µM. The method was successfully applied to determine Cd2+ in water and urine samples and gave recoveries that ranged from 93.3 to 98.6%.  相似文献   

12.
A novel chemically modified electrode for stripping determination of cadmium is presented in this paper, based on carbon nanotube‐hydroxyapatite (CNT‐HAP) nanocomposite, which can be prepared by an easy and effective one‐step sonication. The newly synthesized nanocomposite was characterized with FTIR, TEM, and electrochemical methods. Due to the combination of the strong absorption ability of HAP and excellent electroanalytical properties of CNTs, the GC/CNT‐HAP electrode has been successfully used for determination of Cd2+ by anodic stripping voltammetry with a linear range of 20 nM–3 μM. The sensitivity and detection limit are 25.6 μA/μM and 4 nM, respectively. The practical application of the proposed electrode has been carried out for the determination of trace levels of Cd2+ in real water samples.  相似文献   

13.
采用简便的方法合成了20~40 nm长、56 m^2·g^-1的比表面积的羟基磷灰石纳米管(HAP)。然后用制备的HAP纳米管在水溶液中同时吸附Pb^2+、Cd^2+、Cu^2+、Co^2+、Ni^2+、Zn^2+和Hg^2+,其具有高的吸附能力,并能实现快速去除。此外,制备的HAP纳米管对7种重金属离子的脱附率均小于1%,表现出较强的稳定性。实验数据采用Langmuir等温线模型和Freundlich等温线模型进行分析。2个方程的应用结果表明,吸附平衡最适合Langmuir模型,单层饱和吸附能力为958.28 mg·g^-1,具有较好的吸附性能。通过能量色散X射线光谱(EDS)和X射线衍射(XRD)图进一步研究了吸附机理,结果表明,当溶液中Pb^2+离子数量足够时,吸附机理为Pb取代了HAP中的Ca,形成了更稳定的Pb5(PO4)3(OH)。上述实验研究预测了利用HAP纳米管处理含铅废水在环境污染治理中的可行性。  相似文献   

14.
Phase equilibria were studied in the Nb2O5–CdO system in the Nb2O5-rich region including CdNb2O6 and Cd2Nb2O7. It was determined that CdNb2O6 and Cd2Nb2O7 in air are stable to 1150 and 1120°C, respectively, and that, above these temperatures, there is solid-phase decomposition of niobates with CdO release in the gas phase. Along with the cadmium oxide evaporation, the Cd2Nb2O7 decomposition is accompanied by the formation of cadmium metaniobate CdNb2O6 and the CdNb2O6 decomposition results in the formation of niobium oxide Nb2O5. No thermal events were observed in the differential thermal analysis curve for a 1: 1 CdNb2O6–Cd2Nb2O7 mixture heated to 1100°C in air, which suggests that there are neither phase transformations in cadmium niobates, nor a eutectic within this temperature and concentration ranges. A study of the morphology of compacted samples of niobates determined specific conditions for producing dense composite ceramics, a mixture of niobates, that is suitable for using as a dielectric material.  相似文献   

15.
A series of title complexes with the general molecular formula, K4H2[SiW7Mo4Me(H2O)O39xH2O (denoted as MeW7; Me = Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+), were synthesized. IR spectra, electronic spectra, XPS spectra and thermal analyses were systematically recorded. The crystal structure of MnW7, determined from single-crystal X-ray diffraction at 293?K, belongs to the tetragonal system, space group P4/mnc, Z = 2, a = 1.4105(5) and c = 1.2476(7)?nm. These samples were investigated for the oxidation of cyclohexene with H2O2, and showed more activity than their corresponding parent compounds.  相似文献   

16.
Naphthalenediimides, a class of organic dyes with an expanded π‐electron‐deficient plane, have attracted considerable interest because of their photoinduced electron transfer from neutral organic moieties to stable anionic radicals. This makes them excellent candidates for organic linkers in the construction of photochromic coordination polymers. Such a photochromic two‐dimensional coordination polymer has been prepared using N,N′‐bis(pyridin‐4‐ylmethyl)naphthalene‐1,8:4,5‐bis(dicarboximide) (DPMNI). In crystallization tubes, upon slow diffusion of an MeOH solution of cadmium perchlorate into a CHCl3 solution of DPMNI, the complex poly[[bis[μ2‐2,7‐bis(pyridin‐4‐ylmethyl)benzo[imn][3,8]phenanthroline‐1,3,6,8(2H,7H)‐tetrone‐κ2N:N′]bis(perchlorato‐κO)cadmium(II)] chloroform tetrasolvate], {[Cd(C26H16N4O4)2(ClO4)2]·4CHCl3}n, (I), was obtained. The asymmetric unit contains one Cd2+ cation, two DPMNI ligands, two coordinated ClO4 anions and four CHCl3 solvent molecules. Each Cd2+ cation is interconnected by four DPMNI linkers to generate a neutral two‐dimensional naphthalenediimide coordination network with all the ClO4 anions above or below this plane. Strong interlaminar anion–π interactions between the coordinated ClO4 anions and the imide rings of an adjacent layer lead to a three‐dimensional supramolecular structure. Compound (I) exhibits reversible photochromic behaviour and photocontrolled tunable luminescence properties, which may originate from the photoinduced electron‐transfer generation of radicals in the DPMNI ligand.  相似文献   

17.
In this research, Ni2+ supported on hydroxyapatite-core-shell magnetic γ-Fe2O3 nanoparticles (γ-Fe2O3@HAp-Ni2+) as a novel, efficient, reusable and heterogeneous catalyst was reported. In this protocol, we used this catalyst for the ring opening of epoxide with sodium azide in water. The catalyst can be readily isolated using an external magnet and no obvious loss of activity was observed when the catalyst was reused in seven consecutive runs. The mean size and the surface morphology of the nanoparticles were characterized by transmission electron microscopy, scanning electron microscope, vibrating sample magnetometry, X-ray powder diffraction and Fourier transform infrared techniques.  相似文献   

18.
The solubility products of ZnO (pL = 10.0 ± 0.5) and CdO (pL = 6.8 ± 0.2) in CsI melt at 700°C are determined by potentiometric titration with the use of a Pt(O2)|ZrO2(Y2O3) membrane oxygen electrode. In the Zn-Cd family, metal oxide solubilities grow with increasing metal cation radius. The solubilities in an iodide melt are much lower than in a chloride melt due to a higher basicity of the former; for the Cd2+ cation, the difference between solubilities in these melts is lower owing to the formation of Cd2+-I (soft acid-soft base) complexes.  相似文献   

19.
Analysis of variations in the linear and angular parameters of constituent polyhedra of the cadmium pyrovanadate Cd2V2O7 structure, namely, VO4 tetrahedra and CdO6 octahedra, as calculated from the results of in situ high-temperature X-ray diffraction experiments in the range from 25 to 900°C, showed that, in the range from 600 to 720°C, the thermal expansion coefficient (tec) of CdO6 polyhedra is near zero, whereas VO4 tetrahedra increase in volume, although less strongly than in other temperature ranges. A structural interpretation is given to anomalous temperature dependences of cadmium ion emission and electrical conductivity on the basis of different thermal behavior patterns of the constituent polyhedra of the Cd2V2O7 structure.  相似文献   

20.
This study reports the structural and spectroscopic characterization of a novel metal organic compound formulated as [Fe (bpy)3] [Fe (dipic)2]2.7H2O ( 1 ) (dipic = pyridine‐2,6‐dicarboxylate and bpy = 2,2‐bipyridine). 1 was investigated by elemental analysis, FT‐IR spectroscopy, powder X‐ray diffraction and single crystal X‐ray diffraction (SC‐XRD), which revealed a triclinic structure of expected composition. Thermal degradation of 1 was also investigated. Complex 1 was used as a precursor to prepare superparamagnetic nanoparticles of Fe3O4 by thermal analysis. The obtained Fe3O4 was characterized by Fourier transformed infrared spectroscopy (FT‐IR), powder X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Fe3O4 nanoparticles were used as a nano‐adsorbent to remove Cd2+ from water at room temperature. The results showed that this nano‐adsorbent is effective in removing Cd2+ from contaminated water sources, and that the maximal effectivity of adsorption occurs at pH = 6. Magnetic measurements of complex 1 and Fe3O4 nanoparticles at room temperature revealed paramagnetic and superparamagnetic behavior, respectively.  相似文献   

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