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1.
The metal anions of vanadium (V) and chromium (VI) in aqueous solution can be effectively adsorbed by Zr(IV)-impregnated collagen
fiber (ZrICF). The maximum adsorption capacity of V(V) takes place within the pH range of 5.0 to 8.0, while that of Cr(VI)
is within the pH range of 6.0 to 9.0. When the initial concentration of metal ions was 2.00 mmol L−1 and the temperature was 303 K, the adsorption capacity of V(V) on Zr-ICF was 1.92 mmol g−1 at pH 5.0, and the adsorption capacity of Cr(VI) was 0.53 mmol g−1 at pH 7.0. As temperature increased, the adsorption capacity of V(V) increased, while that of Cr(VI) was almost unchanged.
The adsorption isotherms of the anionic species of V(V) and Cr(VI) can be fit by the Langmuir equation. The adsorption rate
of V(V) follows the pseudo-first-order rate model, while the adsorption rate of Cr(VI) follows the pseudo-second-order rate
model. Furthermore, ZrICF shows high adsorption selectivity to V(V) in the mixture solution of V(V) and Cr(VI). Practical
applications of ZrICF could be expected in consideration of its performance in adsorption of V(V) and Cr(VI). 相似文献
2.
Isaida Shiozawa Giuseppe Lubes Mildred Rodríguez Vito Lubes 《Journal of solution chemistry》2011,40(1):17-25
In this work we present results for the speciation of the ternary complexes formed in the aqueous vanadium(III)–dipicolinic
acid and the amino acids cysteine (H2cys), histidine (Hhis), aspartic acid (H2asp) and glutamic acid (H2glu) systems (25 °C; 3.0 mol⋅dm−3 KCl as ionic medium), determined by means of potentiometric measurements. The potentiometric data were analyzed with the
least-squares program LETAGROP, taking into account the hydrolysis of vanadium(III), the acid-base reactions of the ligands,
and the binary complexes formed. Under the experimental conditions (vanadium(III) concentration = 2–3 mmol⋅dm−3 and vanadium(III): dipicolinic acid: amino acid molar ratio 1:1:1, 1:1:2 and 1:2:1), the following species [V(dipic)(H2asp)]+, [V(dipic)(Hasp)], [V(dipic)(asp)]−, [V(dipic)(asp)(OH)]2−, and [V(dipic)(asp)(OH)2]3− were found in the vanadium(III)–dipicolinic acid–aspartic acid system. In the vanadium(III)–dipicolinic acid–glutamic acid
system [V(Hdipic)(H2glu)]2+, [V(dipic)(H2glu)]+, [V(dipic)(Hglu)], [V(dipic)(Hglu)(OH)]−, and [V(dipic)(Hglu)(OH)2]2− were observed. In the vanadium(III)–dipicolinic acid–cysteine system the complexes [V(dipic)(H2cys)]+, [V(dipic)(Hcys)], [V(dipic)(cys)]−, and [V(dipic)(cys)(OH)]2− were present. And finally, in the vanadium(III)–dipicolinic acid–histidine system the complexes [V(Hdipic)(Hhis)]2+, [V(dipic) (Hhis)]+[\mathrm{V}(\mathrm{dipic}) (\mathrm{Hhis})]^{+}, [V(dipic)(his)], [V(dipic)(his)(OH)]−, and [V(dipic)(his)(OH)2]2− were observed. The stability constants of these complexes were determined. The species distribution diagrams as a function
of pH are briefly discussed. 相似文献
3.
A simple and selective method using ammonium pyrrolidinedithiocarbamate modified activated carbon (APDC-AC) as solid phase
extractant has been developed for speciation of As(III) in water samples. At pH 1.8–3.0, As(III) could be adsorbed quantitatively
by APDC-AC, and then eluted completely with 2.0 mL of 0.1 mol L−1 HNO3, while As(V) could almost not be retained at pH 1–7. Effects of acidity, sample flow rate, concentration of elution solution
and interfering ions on the recovery of As(III) have been systematically investigated. Under the optimal conditions, the adsorption
capacity of APDC-AC for As(III) is 7.3 mg g−1. The detection limit (3σ) of As(III) is 0.05 ng mL−1 for graphite furnace atomic absorption spectrometry (GFAAS) with enrichment factor of 50, and the relative standard deviation
(RSD) is 4.1% (n = 9, C = 5 ng mL−1). The method has been applied to the determination of trace As(III) in water, and the recoveries of As(III) are 100 ± 10%.
Correspondence: Yiwei Wu, Department of Chemistry and Environmental Engineering, Hubei Normal University, Huangshi 435002,
P.R. China 相似文献
4.
B. Das M. V. Reddy G. V. Subba Rao B. V. R. Chowdari 《Journal of Solid State Electrochemistry》2011,15(2):259-268
Nano-composites of SnO(V2O3)
x
(x = 0, 0.25, and 0.5) and SnO(VO)0.5 are prepared from SnO and V2O3/VO by high-energy ball milling (HEB) and are characterized by X-ray diffraction (XRD), scanning electron microscopy, and
high-resolution transmission electron microscopy techniques. Interestingly, SnO and SnO(VO)0.5 are unstable to HEB and disproportionate to Sn and SnO2, whereas HEB of SnO(V2O3)
x
gives rise to SnO2.VO
x
. Galvanostatic cycling of the phases is carried out at 60 mA g−1 (0.12 C) in the voltage range 0.005–0.8 V vs. Li. The nano-SnO(V2O3)0.5 showed a first-charge capacity of 435 (±5) mAh g−1 which stabilized to 380 (±5) mAh g−1 with no noticeable fading in the range of 10–60 cycles. Under similar cycling conditions, nano-SnO (x = 0), nano-SnO(V2O3)0.25, and nano-SnO(VO)0.5 showed initial reversible capacities between 630 and 390 (±5) mAh g−1. Between 10 and 50 cycles, nano-SnO showed a capacity fade as high as 59%, whereas the above two VO
x
-containing composites showed capacity fade ranging from 10% to 28%. In all the nano-composites, the average discharge potential
is 0.2–0.3 V and average charge potential is 0.5–0.6 V vs. Li, and the coulombic efficiency is 96–98% after 10 cycles. The
observed galvanostatic cycling, cyclic voltammetry, and ex situ XRD data are interpreted in terms of the alloying–de-alloying
reaction of Sn in the nano-composite “Sn-VO
x
-Li2O” with VO
x
acting as an electronically conducting matrix. 相似文献
5.
Crosslinked chitosan-bound FeC nanoparticles (CCBFeCNP) were prepared, and the adsorptive behavior of Cr(III) and Cr(VI) on
CCBFeCNP were assessed. At pH 6.0–10.0, CCBFeCNP is selective towards Cr(III) but hardly selective towards Cr(VI). The retained
Cr(III) is subsequently eluted with 0.5 mol L−1 HCl. Total chromium is determined after reduction of Cr(VI) to Cr(III) by ascorbic acid. A new method of flow injection using
a micro-column packed with CCBFeCNP as solid phase extractant has been developed for speciation of Cr(III) and Cr(VI) in water
samples, followed by flame atomic absorption spectrometry. The effects of pH, sample flow rate and volume, elution solution
and interfering ions on the recoveries of Cr(III) were systematically investigated. Under optimum conditions, the adsorption
capacity of CCBFeCNP for Cr(III) is 10.5 mg g−1 at pH 7.5. The procedure presented was applied to chromium speciation in water samples, and the results were satisfactory. 相似文献
6.
A selective, sensitive and simple catalytic method is developed for the determination of vanadium in natural and highly polluted
waste waters. The method is based on the catalytic effect of VV and/or VIV on the bromate oxidative-coupling reaction of metol with phloroglucinol (PG). The reaction is followed spectrophotometrically
by tracing the oxidation product at 464 nm after 10 minutes of mixing the reagents. The optimum reaction conditions are metol
(8.0×10−3 M), PG (4.0×10−3 M) and bromate (2×10−2 M) at 35°C and in presence of an activator-b uffer mixture of 5×10−2 M of each of citric and monochloroacetic acids (pH 2.40). Following the recommended procedure, vanadium can be determined
with a linear calibration graph up to 8.0 ng mL−1 and a detection limit, based on the 3sb criterion, of 0.1 ng mL−1. Spectrophotometric determination of as little as 1.0 ng mL−1 of VV or VIV in aqueous solutions gave an average recovery of 98% with relative standard deviations of ?1.8% (n = 5). The proposed method
was directly applied to the determination of vanadium in Nile river water and highly polluted industrial wastes. Statistical
treatments of analytical results could not detect any systematic error and showed the high accuracy and precision of the developed
method.
Received November 25, 1999. Revision March 10, 2000. 相似文献
7.
A fluorescence quenching method for the determination of vanadium (V) based on the vanadium- catalyzed oxidation of rhodamine
6G (R6G) with periodate in the presence of ethylenediaminetetraacetic acid disodium salt (EDTA) in sulfuric acid medium is
described. The fluorescence was measured with excitation and emission wavelengths of 525 and 555 nm, respectively. The calibration
graph for vanadium (V) had linear ranges of 3.0 × 10−9–1.5 × 10−8 mol/l and 1.5 × 10−8–4.0 × 10−8 mol/l, respectively. The detection limit was 1.7 × 10−9 mol/l. The proposed method was successfully applied to the determination of vanadium (V) in river water, rain water and cast
iron samples.
Received June 29, 2001 Revision October 9, 2001 相似文献
8.
Citric acid was thermochemically esterified onto defatted cotton fibre to produce a carboxyl cotton chelator (CCC), which
had been used for extraction of copper prior to its determination by flame atomic absorption spectrometry. The extraction
of copper has been studied under both batch and column methods. Quantitative extraction of copper was achieved in the pH range
4–7. The time needed to extract each sample was less than 30 min by the batch method. The copper extraction capacity of CCC
was found to be 22.7 mg g−1 at optimal pH value. The elution was quantitative with 1 mol L−1 hydrochloric acid. The feasible flow rate of copper-containing solution for quantitative extraction onto the column packed
with CCC was 0.5–4.0 mL min−1, whereas for elution it was less than 1.5 mL min−1. A 100-fold extraction factor could be achieved under the optimal column conditions. The tolerance limits for common metal
ions on the extraction of copper and the time of column reuse were investigated. The proposed method has been successfully
applied for extraction and determination of copper in industrial wastewater and natural water samples. 相似文献
9.
In this work we prepared the hybrid material (SG) by the sol–gel method through the reaction between tetraethylortosilicate
(TEOS) and acetylacetonatepropyltrimethoxysilane (ACACSIL). We also immobilized the acetylacetonate on silica surface (GR)
by the grafting method through the reaction between a commercial silica and ACACSIL. Infrared thermal analysis showed that
these materials were thermally stable until 200 °C. SG is a microporous material and has surface area of 500 m2 g−1, average porous volume of 0.09 cm3 g−1 and organic content of 1 mmol g−1. GR is a mesoporous material and has surface area of 300 m2 g−1, average porous volume of 0.7 cm3 g−1 and organic content of 0.4 mmol g−1. Iron(III) was coordinated to SG and GR resulting in the SG–Fe and GR–Fe silicas which were tested as catalysts on the aerobic
epoxidation of cis-cyclooctene. SG–Fe yielded 100% of conversion and 94% of selectivity in epoxide whereas GR–Fe silica led
to a maximum conversion of 50% and 100% of selectivity. 相似文献
10.
Franco Varsano Francesca Decker Enrico Masetti 《Monatshefte für Chemie / Chemical Monthly》2001,132(1):83-95
Summary. Ce-V mixed oxide films have been deposited by RF sputtering with the aim of increasing the Li charge capacity of counter
electrodes in smart windows. Such mixed oxides have shown high transmittance and optical passivity in the visible region.
After electrode pre-conditioning by cyclic voltammetry, a good electrochemical reversibility in LiClO4– propylene carbonate electrolyte was observed, and large Li-charge capacity under galvanostatic charging (up to 50 mCċcm−2) has been measured. The electrode charge capacity decreased after prolonged insertion-deinsertion cycles, whereas the photoptic
transmittance remained about constant. After 800 cycles the Li-charge capacity decreased to 40 mCċcm−2. The Li diffusion coefficient inside the films measured by electrochemical impedance and by galvanostatic titration ranged
from 10−11 cm2ċs−1 to 10−13cm2ċs−1. We observed that the Li charge capacity of the film electrodes is a function of the film deposition conditions, because
it increased with the vanadium oxide concentration in the target and with the oxygen content in the sputtering atmosphere.
Received June 23, 2000. Accepted (revised) August 7, 2000 相似文献
11.
Franco Varsano Francesca Decker Enrico Masetti 《Monatshefte für Chemie / Chemical Monthly》2001,15(2):83-95
Ce-V mixed oxide films have been deposited by RF sputtering with the aim of increasing the Li charge capacity of counter electrodes in smart windows. Such mixed oxides have shown high transmittance and optical passivity in the visible region. After electrode pre-conditioning by cyclic voltammetry, a good electrochemical reversibility in LiClO4– propylene carbonate electrolyte was observed, and large Li-charge capacity under galvanostatic charging (up to 50 mCċcm−2) has been measured. The electrode charge capacity decreased after prolonged insertion-deinsertion cycles, whereas the photoptic transmittance remained about constant. After 800 cycles the Li-charge capacity decreased to 40 mCċcm−2. The Li diffusion coefficient inside the films measured by electrochemical impedance and by galvanostatic titration ranged from 10−11 cm2ċs−1 to 10−13cm2ċs−1. We observed that the Li charge capacity of the film electrodes is a function of the film deposition conditions, because it increased with the vanadium oxide concentration in the target and with the oxygen content in the sputtering atmosphere. 相似文献
12.
Gisele B. Tonietto José M. Godoy Ana Cristina Oliveira Marcia V. de Souza 《Analytical and bioanalytical chemistry》2010,397(5):1755-1761
High-performance liquid chromatography (HPLC) coupled to an ICP-MS with an octapole reaction system (ORS) has been used to
carry out quantitative speciation of selenium (Se) and arsenic (As) in the stream waters of a refining process. The argon
dimers interfering with the 78Se and 80Se isotopes were suppressed by pressurizing the octapole chamber with 3.1 mL min−1 H2 and 0.5 mL min−1 He. Four arsenic species arsenite—As(III), arsenate (As(V)), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)—and
three inorganic Se species—selenite Se(IV), selenate Se(VI), and selenocyanate (SeCN−)—were separated in a single run by ion chromatography (IC) using gradient elution with 100 mmol L−1 NH4NO3, pH 8.5, adjusted by addition of NH3, as eluent. Repeatabilities of peak position and of peak area evaluation were better than 1% and about 3%, respectively.
Detection limits (as 3σ of the baseline noise) were 81, 56, and 75 ng L−1 for Se(IV), Se(VI), and SeCN−, respectively, and 22, 19, 25, and 16 ng L−1 for As(III), As(V), MMA, and DMA, respectively. Calibration curve R
2 values ranged between 0.996 and 0.999 for the arsenic and selenium species. Column recovery for ion chromatography was calculated
to be 97 ± 6% for combined arsenic species and 98 ± 3% for combined selenium species. Because certified reference materials
for As and Se speciation studies are still not commercially available, in order to check accuracy and precision the method
was applied to certified reference materials, BCR 714, BCR 1714, and BCR 715 and to two different refinery samples—inlet and
outlet wastewater. The method was successfully used to study the quantitative speciation of selenium and arsenic in petroleum
refinery wastewaters. 相似文献
13.
A new adsorbent is proposed for the solid-phase extraction of phenol and 1-naphthol from polluted water. The adsorbent (TX-SiO2) is an organosilica composite made from a bifunctional immobilized layer comprising a major fraction (91%) of hydrophilic
diol groups and minor fraction (9%) of the amphiphilic long-chain nonionic surfactant Triton X-100 (polyoxyethylated isooctylphenol)
(TX). Under static conditions phenol was quantitatively extracted onto TX-SiO2 in the form of a 4-nitrophenylazophenolate ion associate with cetyltrimethylammonium bromide. The capacity of TX-SiO2 for phenol is 2.4 mg g−1 with distribution coefficients up to 3.4 × 104 mL g−1; corresponding data for 1-naphthol are 1.5 mg g−1 and 3 × 103 mL g−1. The distribution coefficient does not change significantly for solution volumes of 0.025–0.5 L and adsorbent mass less than
0.03 g; 1–90 μg analyte can be easily eluted by 1–3 mL acetonitrile with an overall recovery of 98.2% and 78.3% for phenol
and 1-naphthol, respectively. Linear correlation between acetonitrile solution absorbance (A
540) and phenol concentration (C) in water was found according to the equation A
540 = (6 ± 1) × 10−2 + (0.9 ± 0.1)C (μmol L−1) with a detection range from 1 × 10−8 mol L−1 (0.9 μL g−1) to 2 × 10−7 mol L−1 (19 μL g−1), a limit of quantification of 1 μL g−1 (preconcentration factor 125), correlation coefficient of 0.936, and relative standard deviation of 2.5%. A solid-phase colorimetric
method was developed for quantitative determination of 1-naphthol on adsorbent phase using scanner technology and RGB numerical
analysis. The detection limit of 1-naphthol with this method is 6 μL g−1 while the quantification limit is 20 μL g−1. A test system was developed for naked eye monitoring of 1-naphthol impurities in water. The proposed test kit allows one
to observe changes in the adsorbent color when 1-naphthol concentration in water is 0.08–3.2 mL g−1. 相似文献
14.
Christie Thomas Cherian M. V. Reddy G. V. Subba Rao Chorng Haur Sow B. V. R. Chowdari 《Journal of Solid State Electrochemistry》2012,16(5):1823-1832
Sol–gel auto-combustion method is adopted to prepare solid solutions of nano-crystalline spinel oxides, (Ni1 − x
Zn
x
)Fe2O4 (0 ≤ x ≤ 1).The phases are characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy, selected
area electron diffraction, and Brunauer–Emmett–Teller surface area. The cubic lattice parameters, calculated by Rietveld refinement
of XRD data by taking in to account the cationic distribution and affinity of Zn ions to tetrahedral sites, show almost Vegard’s
law behavior. Galvanostatic cycling of the heat-treated electrodes of various compositions are carried in the voltage range
0.005–3 V vs. Li at 50 mAg−1 up to 50 cycles. Phases with high Zn content x ≥ 0.6 showed initial two-phase Li-intercalation in to the structure. Second-cycle discharge capacities above 1,000 mAh g−1 are observed for all x. However, drastic capacity fading occurs in all cases up to 10–15 cycles. The capacity fading between 10 and 50 cycles is
found to be greater than 52% for x ≤ 0.4 and for x = 0.8. For x = 0.6 and x = 1, the respective values are 40% and 18% and a capacity of 570 and 835 mAh g−1 is retained after 50 cycles. Cyclic voltammetry and ex situ transmission electron microscopy data elucidate the Li-cycling
mechanism involving conversion reaction and Li–Zn alloying–dealloying reactions. 相似文献
15.
A novel method for the determination of five sulfonylurea herbicides in soil was developed by a dispersive solid-phase extraction
(DSPE) clean-up followed by dispersive liquid–liquid microextraction (DLLME), prior to sweeping micellar electrokinetic chromatography
(MEKC). In the DSPE-DLLME, 10 g of soil sample was first extracted with 10 mL of acetonitrile containing 5% formic acid (pH 3.0).
The extract was then cleaned-up by a DSPE with C18 as sorbent. A 1 mL aliquot of the resulting extract was then added into a centrifuge tube containing 5 mL of water adjusted
to pH 2.0 and 60.0 μL chlorobenzene (as extraction solvent) for DLLME procedure. Then, the organic sample extraction solution
was evaporated to dryness, and reconstituted with 20.0 μL of 1.0 mmol L−1 Na2HPO4 (pH 10.0) for sweeping-MEKC analysis after DLLME. Under optimized conditions, the method provided as high as 3,000- to 5,000-fold
enrichments factors. The linearity of the method was in the range of 3.3–200 ng g−1 for chlorimuron ethyl and bensulfuron methyl, and in the range of 1.7–200 ng g−1 for tribenuron methyl, chlorsulfuron and metsulfuron methyl, with the correlation coefficients (r) ranging from 0.9965 to 0.9983, respectively. The limits of detection (LODs) ranged from 0.5 to 1.0 ng g−1. The intraday relative standard deviations (RSDs, n = 5) were below 5.3% and interday RSDs (n = 15) within 6.8%. The recoveries of the method for the five sulfonylureas from soil samples at spiking levels of 5.0, 20.0,
and 100.0 ng g−1 were 76.0–93.5%, respectively. The developed method has been successfully applied to the analysis of the target sulfonylurea
herbicide residues in soil samples with a satisfactory result. 相似文献
16.
Covalent modification of a glassy carbon electrode with penicillamine for simultaneous determination of hydroquinone and catechol 总被引:1,自引:0,他引:1
Liang Wang Peng Fei Huang Jun Yue Bai Hong Jing Wang Li Ying Zhang Yu Qing Zhao 《Mikrochimica acta》2007,158(1-2):151-157
A simple and highly selective electrochemical method has been developed for the simultaneous determination of hydroquinone
(HQ) and catechol (CC) at a glassy carbon electrode covalently modified with penicillamine (Pen). The electrode is used for
the simultaneous electrochemical determination of HQ and CC and shows an excellent electrocatalytical effect on the oxidation
of HQ and CC upon cyclic voltammetry in acetate buffer solution of pH 5.0. In differential pulse voltammetric measurements,
the modified electrode was able to separate the oxidation peak potentials of HQ and CC present in binary mixtures by about
103 mV although the bare electrode gave a single broad response. The determination limit of HQ in the presence of 0.1 mmol L−1 CC was 1.0 × 10−6 mol L−1, and the determination limit of CC in the presence of 0.1 mmol L−1 HQ was 6.0 × 10−7 mol L−1. The method was applied to the simultaneous determination of HQ and CC in a water sample. It is simple and highly selective. 相似文献
17.
Leydi Erika Sarmiento Mildred Rodríguez Lorenzo Echevarria Vito Lubes 《Journal of solution chemistry》2010,39(10):1484-1491
The complex species formed between vanadium(III) and 1,10-phenanthroline (phen), 2,2′-bipyridine (bipy), and 8-hydroxyquinoline
(8hq) were studied in aqueous solution by means of electromotive forces measurements, emf(H), at 25 °C with 3.0 mol⋅dm−3 KCl as the ionic medium. The potentiometric data were analyzed using the least-squares computational program LETAGROP, taking
into account the hydrolytic vanadium(III) species formed in solution. Analysis of the vanadium(III)–phen system data shows
the formation of [VHL]4+, [V(OH)L]2+, [V2OL2]4+ and [V2OL4]4+ complexes. In the vanadium(III)–bipy system the [VHL]4+, [V(OH)L]2+, [V2OL2]4+ and [V2OL4]4+ complexes were observed, and in the vanadium(III)–8hq system the complexes [V(OH)L]+, [V(OH)2L], [VL2]+ and [VL3] were detected. 相似文献
18.
Akhmad Sabarudin Osamu Noguchi Mitsuko Oshima Keiro Higuchi Shoji Motomizu 《Mikrochimica acta》2007,159(3-4):341-348
Chitosan resin functionalized with 3,4-dihydroxy benzoic acid (CCTS-DHBA resin) was used as a packing material for flow injection
(FI) on-line mini-column preconcentration in combination with inductively coupled plasma-atomic emission spectrometry (ICP-AES)
for the determination of trace elements such as silver, bismuth, copper, gallium, indium, molybdenum, nickel, uranium, and
vanadium in environmental waters. A 5-mL aliquot of sample (pH 5.5) was introduced to the minicolumn for the adsorption/preconcentration
of the metal ions, and the collected analytes on the mini-column were eluted with 2 M HNO3, and the eluates was subsequently transported via direct injection to the nebulizer of ICP-AES for quantification. The parameters
affecting on the sensitivity, such as sample pH, sample flow rate, eluent concentration, and eluent flow rate, were carefully
examined. Alkali and alkaline earth metal ions commonly existing in river water and seawater did not affect the analysis of
metals. Under the optimum conditions, the method allowed the determination of metal ions with detection limits of 0.08 ng mL−1 (Ag), 0.9 ng mL−1 (Bi), 0.07 ng mL−1 (Cu), 0.9 ng mL−1 (Ga), 0.9 ng mL−1 (In), 0.08 ng mL−1 (Mo), 0.09 ng mL−1 (Ni), 0.9 ng mL−1 (U), and 0.08 ng mL−1 (V). By using 5 mL of sample solution, the enrichment factor and collection efficiency were 8–12 fold and 96–102%, respectively,
whereas the sample throughput was 7 samples/hour. The method was validated by determining metal ions in certified reference
material of river water (SLRS-4) and nearshore seawater (CASS-4), and its applicability was further demonstrated to river
water and seawater samples. 相似文献
19.
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
20.
A quaternary super-ion-conducting system, 20CdI2 − 80[xAg2O − y(0.7V2O5 − 0.3B2O3)] where 1 ≤ x/y ≤ 3, has been prepared by melt quenching technique. The electrical conductivity measured was the order of 10−4 S/cm at room temperature. The values of silver-ion transport number obtained by electromotive force technique are nearly
unity. The thermoelectric power and electrochemical studies were done on the CdI2–Ag2O–V2O5–B2O3 system. The discharge and polarization characteristics were examined for different cathodes to evaluate the utility of these
cells as power sources for low energy applications. 相似文献