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1.
We report on the separation and preconcentration of lead(II) and copper(II) ions using silver-coated titanium dioxide nanoparticles modified with cysteamine, and their determination by slurry analysis via flame atomic absorption spectrometry. The ions were adsorbed via a conventional batch technique, and the ion-loaded slurry was separated and directly introduced into the spectrometer, thereby eliminating a number of drawbacks. The effects of pH, amount of sorbent, slurry volume, sample volume and other ions on the recovery were investigated. Under optimized experimental conditions, copper and lead can be recovered within the 95% confidence level in certificated waste water, but also in spiked sea water samples. The technique is fast, simple, and leads to complete elution. The limit of detection (3δ, at n?=?10) was 0.37 μg L?1 for Cu(II), and 0.38 μg L?1 for Pb(II).
Figure
We report on the separation and preconcentration of lead(II) and copper(II) ions using silver-coated titanium dioxide nanoparticles modified with cysteamine (Fig. 1), and their determination by slurry analysis via flame atomic absorption spectrometry. Under optimized experimental conditions, copper and lead can be recovered within the 95% confidence level in certificated waste water and spiked sea water samples. The technique is fast, simple, and leads to complete elution. Figure 1. Schematic illustration of the preparation of TiO2@Ag–Cysteamine nanoparticles and inset shows the color of the nanoparticles.  相似文献   

2.
A solid phase extraction procedure for the separation and preconcentration of trace amounts of Cd(II) and Pb(II) using the alizarin red S modified TiO2 nanoparticles prior to their determination by flame atomic absorption spectrometry has been proposed. The influences of some analytical parameters such as pH, flow rates of sample and eluent, type and concentration of the eluent, and interfering ions on the recovery of Cd(II) and Pb(II) by the sorbent were investigated. The analytes were quantitatively sorbed from the aqueous solution at pH 5.5 onto a microcolumn packed with the sorbent and recovered with 2.0?mL of 1.5?mol?L?1 hydrochloric acid. Under the optimum experimental conditions, the detection limits for Cd(II) and Pb(II) were 0.11 and 0.30?ng?mL?1 and the relative standard deviations for ten replicate measurements of 5.0 and 50.0?ng?mL?1 of Cd(II) and Pb(II) were 2.1 and 1.9%, respectively. A sample volume of 200?mL resulted in a preconcentration factor of 100. The method was successfully applied to the determination of Cd(II) and Pb(II) in water and biological samples, and accuracy was examined by the recovery experiments, independent analysis using electrothermal atomic absorption spectrometry, and analysis of a water standard reference material (SRM 1643e).  相似文献   

3.
Silica gel was prepared by the sol–gel method, modified with nanometer-sized zirconium oxide, and this material was characterized by X-ray diffraction. A micro-column packed with silica gel modified with nanometer zirconium oxide as sorbent has been developed for the quantitative separation and preconcentration of trace amounts of chromium(III) prior to their determination by electrothermal atomic absorption spectrometry. Total chromium was determined after the reduction of chromium(VI) to chromium(III) by 10% (m/v) of aqueous ascorbic acid as reducing reagent. The adsorption capacity for chromium(III) was found to be 2.36 mg g−1. The detection limit for chromium(III) was 15 ng L−1 with an enrichment factor of 100. The relative standard deviation was 3.2% (n = 7, c = 2.0 ng mL−1).  相似文献   

4.
The present article reports the application of Thiosemicarbazide‐modified multiwalled carbon nanotubes (MWCNTs‐TSC) as a new, easily prepared selective and stable solid sorbent for the preconcentration of trace Co(II), Cd(II), Cu(II) and Zn(II) ions in aqueous solution prior to the determination by flame atomic absorption spectrometry. The studied metal ions can be adsorbed quantitatively on MMWNTs at pH 5.0 and then eluted completely with HNO3 (1.5 mol L?1) prior to their determination by flame atomic absorption spectrometry. The separation/preconcentration conditions of analytes were investigated, including the pH, the sample flow rate and volume, the elution condition and the interfering ions. The maximum adsorption capacity of the adsorbent at optimum conditions were found to be 32.5, 27.3, 44.5 and 34.1 mg g?1 for Co(II), Cd(II), Cu(II) and Zn(II), and the detection limits of the method were found to be 0.28, 0.13, 0.21 and 0.17 μg L?1, respectively. The proposed method was successfully applied for extraction and determination of the analytes in well water, sea water, wastewater, soil, and blood samples.  相似文献   

5.
Au core Ag shell composite structure nanoparticles were prepared using a sol method. The Au core Ag shell composite nanoparticles were loaded on TiO2 nanoparticles as support using a modified powder–sol method, enabling the generation of Au @ Ag/TiO2 photocatalysts for photocatalytic decomposition and elimination of ozone. The sols were characterized by means of ultraviolet–visible light (UV–Vis) reflection spectrometry, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The activity of the Au @ Ag/TiO2 photocatalysts for photocatalytic decomposition and elimination of ozone was evaluated and the effect of Cl? anions on the photocatalytic activity of the catalysts was highlighted. Results showed that Au @ Ag/TiO2 prepared via the modified powder–sol route in the presence of an appropriate amount of NaCl solid as demulsifier had better activity in the photocatalytic decomposition and elimination of ozone. At the same time, Au @ Ag/TiO2 catalysts had better ability to resist poisonous Cl? anions than conventional Au/TiO2 catalyst. The reasons could be, first, that NaCl was capable of reducing the concentration of free Ag+ by adsorption on the surface of Ag particles forming AgCl and enhancing the formation of Au core Ag shell particles, leading to a better resistance to Cl? anions of the catalysts, and, second, AgCl took part in the photocatalytic decomposition of ozone together with Au @ Ag/TiO2 catalysts and had a synergistic effect on the latter, resulting in better photocatalytic activity of Au @ Ag/TiO2 catalysts.  相似文献   

6.
用浸渍-分解法将Bi2O3纳米颗粒沉积在TiO2纳米管壁上, 制备了Bi2O3/TiO2纳米管阵列. 用电感耦合等离子体发射光谱(ICP-AES)测定了Bi2O3/TiO2 纳米管阵列的化学组分, 利用X 射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和紫外-可见(UV-Vis)吸收光谱表征了所制备的样品. 通过在可见光下(λ>400 nm)降解甲基橙(MO)水溶液来评价样品的光催化活性. 结果表明, Bi2O3纳米颗粒均匀地沉积在TiO2纳米管中. Bi2O3/TiO2纳米管阵列具有比纯Bi2O3膜和N-TiO2纳米管阵列高得多的可见光催化活性. Bi2O3/TiO2纳米管阵列活性的增强是其强可见光吸收和Bi2O3与TiO2之间形成的异质结的协同作用的结果.  相似文献   

7.
Uniform flower-like TiO2 coated Au nanostars and core-shell Au@Ag nanostars with different amounts of Ag coating were prepared through a facile method by hydrolysis of TiF4 under an acidic environment. The photocatalytic capability of these flower-like nanocomposites under visible light irradiation was found to be enhanced by up to 4.7-fold compared to commercial P25 TiO2 nanoparticles. The enhanced photocatalytic activity was ascribed to improved light absorption and hot electron injection from the photo-excited Au@Ag core to the TiO2 shell.  相似文献   

8.
A new method using dithizone-modified TiO2 nanoparticles (nanometer TiO2-DZ) as solid-phase extractant has been developed for the simultaneous preconcentration of trace amounts of chromium and lead prior to their measurement by inductively coupled plasma atomic emission spectrometry (ICP-AES). The preconcentration conditions of the analytes, including the effects of pH, sample flow rate and volume, elution conditions and interfering ions on the recovery of the analytes were investigated. At pH 5, the adsorption capacity of the nanometer TiO2-DZ was found to be 5.8 mg g−1 and 22.5 mg g−1 for Cr and Pb, respectively. According to the definition of IUPAC, the detection limits (3σ) of this method for Cr and Pb were 0.38 and 1.72 ng mL−1, respectively. The proposed method was applied to the determination of trace chromium and lead in foodstuffs, plants and water samples with satisfactory results.  相似文献   

9.
A procedure was developed for determining chromium(VI) in the soil organic fraction; it consisted of three steps: the preparation of a soil solution; the isolation and separation of chromium(VI) and chromium(III); and the determination of chromium(VI). Soil solutions were prepared by leaching soil samples with a Na4P2O7 solution (the Rudd method). Chromium(VI) was extracted from the soil solution with a solution of sodium diethyldithiocarbamate in n-amyl alcohol; the conditions of the extraction and separation of chromium(VI) and chromium(III) were optimized. Chromium(VI) in solutions was determined after back extraction by spectrophotometry with diphenylcarbazide or by flame atomic absorption spectrometry. The procedure was validated using a reference soil sample, and the material balance of chromium in the systems under study was calculated.  相似文献   

10.
In this paper, we prepared TiO2@CdS core–shell nanorods films electrodes using a simple and low-cost chemical bath deposition method. The core–shell nanorods films electrodes were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV–vis spectrometry techniques. After applying these TiO2@CdS core–shell nanorods electrodes in photovoltaic cells, we found that the photocurrent was dramatically enhanced, comparing with those of bare TiO2 nanorods and CdS films electrodes. Moreover, TiO2@CdS core–shell nanorods film electrode showed better cell performance than CdS nanoparticles deposited TiO2 nanoparticles (P25) film electrode. A photocurrent of 1.31 mA/cm2, a fill factor of 0.43, an open circuit photovoltage of 0.44 V, and a conversion efficiency of 0.8% were obtained under an illumination of 32 mW/cm2, when the CdS nanoparticles deposited on TiO2 nanorods film for about 20 min. The maximum quantum efficiency of 5.0% was obtained at an incident wavelength of 500 nm. We believe that TiO2@CdS core–shell heterostructured nanorods are excellent candidates for studying some fundamental aspects on charge separation and transfer in the fields of photovoltaic cells and photocatalysis.  相似文献   

11.
This study describes the successful sequential modification of multi-walled carbon nanotube (MWCNT) by Fe3O4 magnetic nanoparticles and 2-mercaptobenzothiazole (MBT) followed by its application as a novel sorbent for simultaneous magnetic solid phase microextraction of lead and cadmium. Fourier transform infrared spectroscopy and scanning electron microscopy were employed to confirm the chemical surface modification of the MWCNT. The ions retained on the 2-MBT/magnetic nanoparticles modified MWCNTs were eluted with 1.0 mL of nitric acid (0.8 mol L?1) in methanol solution and determined by the flame atomic absorption spectrometry. All parameters affecting the extraction condition were thoroughly investigated and optimised. Under the optimised condition preconcentration factor of 150.0, enhancement factors of 149.0 and 149.2 and limits of detection of 0.21 and 0.01 µg L?1 were achieved for lead and cadmium, respectively. Using the prepared magnetic nanocomposite, the possible interference of other common ions associated with lead and cadmium determination was effectively avoided and the method was successfully applied to the simultaneous determination of the target ions in various environmental water samples.  相似文献   

12.
Novel magnetic chromium and sulfur co-doped TiO2 photocatalysts (M-Cr/S/TiO2) have been prepared by a sol?Cgel process, using magnetic hollow fly ash microspheres as support material. The crystal phase of M-Cr/S/TiO2 was characterized by X-ray diffraction, UV?Cvisible absorption spectroscopy, and transmission electron microscopy. The photocatalytic activity of the photocatalysts was examined by photodegradation of methyl orange in aqueous solution under visible light irradiation. The results showed that chromium and sulfur co-doped catalysts (Cr/S/TiO2) containing 0.60?% (atomic ratio) chromium and 1.2?% (atomic ratio) sulfur calcined at 450?°C for 2?h had high catalytic efficiency under visible irradiation. It is worth mentioning that the floating M-Cr/S/TiO2 catalyst had greater photocatalytic activity than Cr/S/TiO2 powder. Therefore, M-Cr/S/TiO2 is a promising, high-performing, visible-light-driven photocatalyst.  相似文献   

13.
A novel and facile method was developed to prepare a visible‐light driven TiO2/Ag‐AgCl@polypyrrole (PPy) photocatalyst with Ag‐AgCl nanoparticles supported on TiO2 nanofibers and covered by a thin PPy shell. During the synthesis, the PPy shell and Ag‐AgCl nanoparticles were prepared simultaneously onto TiO2 nanofibers, which simplified the preparation procedure. In addition, because Ag‐AgCl aggregates were fabricated via partly etching the Ag nanoparticles, their size was well controlled at the nanoscale, which was beneficial for improvement of the contact surface area. Compared with reference photocatalysts, the TiO2/Ag‐AgCl@PPy composite exhibited an enhanced photodegradation activity towards rhodamine B under visible‐light irradiation. The superior photocatalytic property originated from synergistic effects between TiO2 nanofibers, Ag‐AgCl nanoparticles and the PPy shell. Furthermore, the TiO2/Ag‐AgCl@PPy composite could be easily separated and recycled without obvious reduction in activity.  相似文献   

14.
A new modified nanometer SiO2 using 5-sulfosalicylic acid (SSA) as a solid-phase extractant was used for separation, preconcentration and determination of Fe(III) in aqueous solutions by inductively coupled plasma atomic emission spectrometry (ICP-AES). Its adsorption and preconcentration behaviour for Fe(III) in aqueous solutions was investigated using static procedures in detail. The optimum pH value for the separation of Fe(III) on the newly designed sorbent was 3.5. Complete elution of the adsorbed Fe(III) from the nanometer SiO2-SSA was carried out using 2.0 mL of 0.01 mol L− 1 of HCl. The time of 90% sorption was less than 2 min for Fe(III) at pH 3.5. Common coexisting ions did not interfere with the separation and determination of Fe(III) at pH 3.5. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 44.01 mg of Fe(III) per gram of sorbent. The relative standard deviation (RSD) of the method under optimum conditions was 3% (n = 5). The procedure was validated by analyzing three certified reference materials (GBW 08301, GBW 08504, GBW 08511), the results obtained were in good agreement with standard values. The nanometer SiO2-SSA was successfully employed in the separation and preconcentration of the investigated Fe(III) from the biological and natural water samples yielding 100-folds concentration factor.  相似文献   

15.
Liu Y  Liang P  Guo L 《Talanta》2005,68(1):25-30
Nanometer titanium dioxide immobilized on silica gel (immobilized nanometer TiO2) was prepared by sol-gel method and characterized by using X-ray diffraction (XRD) and scanning electron microscope (SEM). The adsorptive potential of immobilized nanometer TiO2 for the preconcentration of trace Cd, Cr, Cu and Mn was assessed in this work. The metal ions studied can be quantitative retained at a pH range of 8-9, and 0.5 mol L−1 HNO3 was sufficient for complete elution. The adsorption capacity of immobilized nanometer TiO2 for Cd, Cr, Cu and Mn was found to be 2.93, 2.11, 6.69 and 2.47 mg g−1, respectively. A new method using a microcolumn packed with immobilized nanometer TiO2 as sorbent has been developed for the preconcentration of trace amounts of Cd, Cr, Cu and Mn prior to their determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). The method has been successfully applied for the determination of trace elements in some environmental samples with satisfactory results.  相似文献   

16.
Pei Liang  Qian Li  Rui Liu 《Mikrochimica acta》2009,164(1-2):119-124
A new method has been developed for the determination of trace molybdenum based on separation and preconcentration with TiO2 nanoparticles immobilized on silica gel (immobilized TiO2 nanoparticles) prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS). The optimum experimental parameters for preconcentration of molybdenum, such as pH of the sample, sample flow rate and volume, eluent and interfering ions, have been investigated. Molybdenum can be quantitatively retained by immobilized TiO2 nanoparticles at pH 1.0 and separated from the metal cations in the solution, then eluted completely with 0.5 mol L?1 NaOH. The detection limit of this method for Mo was 0.6 ng L?1 with an enrichment factor of 100, and the relative standard deviation (RSD) was 3.4% at the 10 ng mL?1 Mo level. The method has been applied to the determination of trace amounts of Mo in biological and water samples with satisfactory results.  相似文献   

17.
N,N'-bis-(α-methylsalicylidene)-2,2-dimethyl-1,3-propanediimine (SBTD) modified silica gel was prepared and used as sorbent for solid phase extraction of Cr(III) ions from aqueous solution. This sorbent showed a high sorption affinity for Cr(III) while recovery of Cr(VI) was very low. The analyte ion retained on the column was eluted with 1 mol L(-1) HNO(3). The chromium ion in the eluent was determined by graphite furnace atomic absorption spectrometry. The effects of different parameters such as pH, eluent type and volume, Schiff's base concentration, sample and eluent flow rate, interfering ions and adsorbent amount were investigated.  相似文献   

18.
A sol–gel method has been proposed to prepare uniform TiO2 nanoparticles whose average size is about 30 nm. The prepared nanometer TiO2 particles are modified by acetamide via different self-assembled processes. X-ray diffraction analyses, scanning electron microscopy, and Fourier transform infrared spectrometry are used to determine the structure of the nanoparticles. The results indicate that the different synthesis processes do not change the morphology of the TiO2/acetamide nanoparticles; nevertheless, they affect the interaction between amide and acetamide. The electrorheological (ER) activity is studied by shear stress under DC electric field. The acetamide-modified TiO2 ER fluid shows notable ER activity with shear stress about 45 kPa (at 5 kV/mm), which outclasses the shear stress (2 kPa) of unmodified TiO2 ER fluid. It is also found that the ER effect is very sensitive to the interaction of molecules on TiO2 particles. The chemical bond between core and shell can enhance the ER activity of the sample.  相似文献   

19.
Phospholipids possess important physiological, structural and nutritional functions in biological systems. This study described a solid-phase extraction (SPE) method, employing graphene and titanium dioxide (G/TiO2) nanocomposite as sorbent, for the selective isolation and enrichment of phospholipids from avocado (Persea americana Mill.). Based on the principal that the phosphoryl group in the phospholipid can interact with TiO2 via a bridging bidentate mode, an optimum condition was established for SPE, and was successfully applied to prepare avocado samples. The extracts were monitored by matrix-assisted laser desorption ionization time-of-flight/tandem mass spectrometry (MALDI-TOF/MS) in both positive-ion and negative-ion modes. Results showed that phospholipids could be efficiently extracted in a clean manner by G/TiO2 based SPE. In addition, the signals of phospholipids were enhanced while the noise was reduced. Some minor peaks became more obvious. In conclusion, the nanocomposite material of G/TiO2 was proved to be a promising sorbent for selective separation of phospholipids from crude lipid extract.  相似文献   

20.
A nitrogen doped TiO2/Ni0.5Zn0.5Fe2O4 core–shell structure nanoparticles was prepared by low temperature sol–gel-hydrothermal process. The characterizations of the catalyst indicate that the Ni0.5Zn0.5Fe2O4 nanocrystals of about 25 nm are well-coated with crystalline N-doped titania. The absorption edges in the diffusion reflectance spectra of TiO0.98N1.02 and TiO1.37N0.63/Ni0.5Zn0.5Fe2O4 shift to visible light region. The core–shell nanocatalysts can effectively photodegrade organic pollutants in the dispersion system and can be recycled easily by an external magnetic field.  相似文献   

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