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1.
Comparison of hexamethylenedithiocarbamate and tetramethylenedithiocarbamate as flotation reagents for the concentration of zinc 总被引:1,自引:0,他引:1
Gorica Pavlovska Traje Stafilov Katarina undeva 《Fresenius' Journal of Analytical Chemistry》1998,361(2):213-216
A procedure for zinc flotation separation from fresh water prior to its determination by atomic absorption spectrometry (AAS)
has been developed. Hexamethyleneammonium hexamethylenedithiocarbamate (HMA-HMDTC) added to the first precipitate collector
of hydrated Fe(III) oxide (Fe2O3· xH2O) gives the second precipitate collector of Fe(HMDTC)3. After addition of a surfactant, the precipitate of collectors is separated from the water phase by a stream of air bubbles,
dissolved by strong acid and the solution then tested by AAS. The experimental parameters (amount of collector used, pH, ionic
strength, type of foaming reagent, ζ potential, induction time etc.) affecting the flotation efficiency were optimized. At
a pH of 6, Zn is separated quantitatively (98.5%) by addition of 5 mg Fe(III) and 3 mL 0.1 mol/L HMA-HMDTC to the sample.
Results are compared with those obtained by ammonium tetramethylenedithiocarbamate.
Received: 21 August 1997 /Revised: 19 November 1997 / Accepted: 23 November 1997 相似文献
2.
Colloid flotation of zinc from fresh water with a combination of two collectors, hydrated iron(III) oxide (Fe(2)O(3).xH(2)O) and iron(III) tetramethylenedithiocarbamate (Fe(TMDTC)(3)), permits rapid separation of the precipitate before its atomic absorption spectrometric (AAS) analysis. All important parameters necessary for the successful flotation like optimal mass of collectors, pH of the medium, electrokinetic potential of the collector particle surfaces, type of tenside, induction time etc., were checked. At the optimal pH value of medium (5.5) establishing by recommended procedure, zinc was separated quantitatively (97.4-98.8%) with 5 mg Fe(III) as constitutive element of the two collectors used. The content of zinc was determined by flame atomic absorption spectrometry (FAAS). These results were compared with the results obtained by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The FAAS detection limit for zinc is 9.4 mug 1(-1). The proposed method is simple, rapid and applicable to the zinc separation at mug 1(-1) levels from a large volume of water. 相似文献
3.
Tl(I) and Tl(III) are preconcentrated simultaneously from aqueous solutions by colloid precipitate flotation using two collectors: hydrated iron(III) oxide (Fe2O3·xH2O) and iron(III) tetramethylenedithiocarbamate (Fe(TMDTC)3). After the coprecipitation step and the addition of foaming agents, Tl(I) and Tl(III) were separated from the water by a stream of air bubbles. Various factors affecting Tl(I) and Tl(III) recoveries during the separation from water, including the collector mass, the nature of the supporting electrolyte, pH, ζ potential of the collector particle surfaces, type of tenside, etc., were investigated. Within the optimal pH range (6–6.5), establishing by a recommended procedure, Tl(I) and Tl(III) were separated quantitatively (94.9–100.0%) with 30 mg Fe(III). Both Tl ions were simultaneously separated without any previous conversion of one type of Tl ion to the other. Total Tl determination was performed by electrothermal atomic absorption spectrometry by previous matrix modification of the concentrated samples. The determination limit of Tl by this method is 0.108 μg l−1. 相似文献
4.
In the paper, simultaneous removal of Al(III) and Cu(II) from dilute aqueous solutions by ion and precipitate flotation methods is investigated. Influence of the pH of the initial solution, the surface active collector concentration and the gas flow rate on the final removal ratio and the course of ion and precipitate flotations is presented. The results show that simultaneous flotations of Al(OH)3 and Cu(OH)2 insoluble species occur allowing to achieve their almost complete removal in the pH range between 7 and 9. An increase of the surface active agent concentration causes a decrease of the final removal ratio as well as of the flotation rate constant. An increase of the gas flow rate results in an increase of ion and precipitate flotation rates. 相似文献
5.
The separation behavior of mercury by a flotation system consisting of ammonium sulfate, ammonium thiocyanate and ethyl violet, and the conditions for the separation of Hg(II) with other common metal ions have been studied. The studies show that in aqueous solutions, Hg(II) combines with NH4SCN and ethyl violet(EV) into dissoluble ternary ion‐association complex [Hg(SCN)42?]?(EV)2. In the presence of ammonium sulfate, the precipitate is floats well on the surface of the water phase and separates from water thoroughly. It shows that Hg(II) can be separated completely from Cd(II), Fe(II), Co(II), Ni(II), Mn(II) and Al(III) by flotation at pH1.0. The flotation mechanism of Hg(II) is described in this paper. 相似文献
6.
Colloid precipitate flotation of silver from fresh water is applied for preconcentration and separation. Optimal conditions using hydrated iron(III) oxide and iron(III) tetramethylenedithiocarbamate as collectors were investigated. Various factors affecting the silver recovery, including collector mass, nature of the supporting electrolyte, pH of the working medium, electrokinetic potential of the collector particle surfaces, type of surfactant, induction time etc., were checked. Within the optimal pH range (5.5–6.5) silver was separated quantitatively (94.9– 100.0%) with 30 mg Fe(III) as collector. The content of silver was determined by electrothermal atomic absorption spectrometry and compared to that from inductively coupled plasma-atomic emission spectrometry. The detection limit of silver by the method described is 0.01 μg/L. 相似文献
7.
Traces of Fe, Co, Ni, Cu, Zn, Cd and Pb in salt solutions (e.g. KCl, Ca(NO3)2, A12(SO4)3, Cr2(SO4)3, (NH4)2SO4) are determined by flame AAS after preconcentration with thiuram disulphide (TDS) as collector precipitate. The preconcentration recovery is mainly influenced by pH, TDS amount and its aging in the sample solution. Conditions of an optimal preconcentration procedure were elaborated. Detection limits vary from 0.5 ng/ml (for Cd) to 8.3 ng/ml (for Pb) and the relative standard deviation is 2 to 6 %. The accuracy of the results was checked by differential pulse anodic stripping voltammetry and by electrothermal AAS. 相似文献
8.
The applicability of tetramethylenedithiocarbamate (TMDTC−) and hexamethylenedithiocarbamate (HMDTC−) for colloid flotation separation of manganese in traces from fresh (spring, well and tap) water was studied. The experimental
conditions for the successful manganese separation and preconcentration before electrothermal atomic absorption spectrometric
(ETAAS) determination were optimised. Higher enrichment of manganese was achieved when a larger amount of HMDTC− is used. Applying iron(III) hexamethylenedithiocarbamate, Fe(HMDTC)3, as a precipitate collector, manganese was determined at μg/L levels singly or simultaneously with lead and zinc in 1 L of
water sample. The applicability of the proposed procedure have been verified by analyses of fresh water samples using the
method of standard addition, as well as by comparing the results obtained by ETAAS with those obtained by inductively coupled
plasma-atomic emission spectrometry (ICP-AES). The detection limit of manganese using this method is 0.025 μg/L.
Received August 30, 1999. Revision May 15, 2000 相似文献
9.
Ion, precipitate and adsorbing colloid flotation of cobalt(II) have been investigated at different pH values, using N-dodecylpyridinium chloride (DPCl), A strong cationic surfactant, and sodium lauryl sulfate (NaLS), a strong anionic surfactant, as collectors. In case of adsorbing colloid flotation, hydrous manganese dioxide was used as an adsorbent. The precipitate flotation curves experimentally obtained with the two tested collectors were compared with the corresponding theoretical one calculated from the data published for Co(II) hydrolysis. The effects of the collector concentration, ageing of the water-MnO2–Co(II) system, bubbling time period, cobalt(II) concentration and foreign salts on the percent removal of Co(II) by adsorbing colloid flotation using DPCl as collector were determined. Removals approaching 100% could be achieved under the optimum conditions. 相似文献
10.
The flotation separation behavior of lead with Sodium Nitrate‐Potassium Iodide‐Cetyltrimethyl Ammonium Bromide system and the conditions for the separation of lead with other metal ions are studied in this research. With 0.1 M potassium iodide, 1.0 × 10?2 M Cetyltrimethyl Ammonium Bromide and 1.0 g/10 mL of sodium nitrate, Pb(II) can form an ion‐association complex (PbI42?) (CTMAB+)2 and be separated completely from Zn(II), Fe(III), Co(II), Ni(II), Mn(II) and Al(III) by flotation at pH = 1.0–3.0. 相似文献
11.
Summary A cellulose collector with immobilized triethylenetetraminepentaacetic acid (TETPA) groups has been developed for multielement preconcentration (e.g., Al, Be, Bi, Cd, Co, Cu, Fe(III), In, Mn, Ni, Pb, Tl(III), U(VI), V(IV), Zn) using a low-pressure flow system. Analyte distribution coefficients Kd of the order of 104–105 ml/g (0.5 mol/l NaCl, pH 3–8) and fast exchange kinetics enable effective trace/matrix separations by means of small TETPA-filled (75 mg) columns even at high flow rates (contact time<1 s). Accordingly, recovery rates ranging from 88 (Tl(III)) to 99.5% (Ni), relative standard deviations sr mostly between 1.5 and 4.0% (off-line determined by flame AAS) and blank levels (e.g., Cu, Fe, Zn) in the lower ng range (quantified by ETAAS) can be achieved. Metal-complexing dissolved organic substances (e.g. humic substances), however, considerably lower the recovery rates of some analytes (e.g., Cu, Fe, Ni). A series of water analyses (e.g., river, sea, bog water) prove the reliability of the developed flow-preconcentration system.Dedicated to Prof. Dr. V. Krivan on the occasion of his 60th birthday 相似文献
12.
The behavior and conditions of liquid‐liquid extraction‐separation of Fe(III) by ammonium thiocyanate‐H2O‐n‐propyl alcohol system in the presence of NaCl were studied, and the possible reactive mechanism of extraction of Fe(III) was deduced. The study showed that, in the presence of a given amount of NaCl, phases were separated thoroughly between n‐propyl alcohol and water. In the process of phase separation, the complex [Fe(SCN)n](3‐n) formed by NH4SCN and Fe(III) was quantitatively extracted into the n‐propyl alcohol phase. The extracted Fe(III) exists in the n‐propyl alcohol phase mainly as the forms of Fe(SCN)2+ and Fe(SCN)3. Also, the relationship between extraction yield of Fe(III) and the amount of NH4SCN agreed well with the quadratic equation E = 0.54 + 58.14x ? 8.39x2 (E and x represent the recovery rate of Fe(III) and the volume (mL) of 0.1 M NH4SCN respectively). The quadratic R‐Square is 0.9990. With this method, Fe(III) can be completely separated from Co(II), Ni(II), Mn(II), Al(III), Bi(III) and Cd(II) at pH 1.0?2.0. The present method was applied in determining Fe(III) in samples with satisfactory results such as relative standard deviation from 2.06% to 2.89% and recovery rate in the range of 98.4?101.4%. 相似文献
13.
The liquid-liquid extraction, ion and precipitate flotation of Co(II) from chloride media of 1·10–4M initial Co(II) concentration and =0.1 have been investigated using decanoic acid and the results are compared. Organic solvents used were chloroform in the case of liquid-liquid extraction and ethanol (used as a solvent for the collector and a frother) in the case of flotation. From the results it appears that liquid-liquid extraction takes place through the formation of the complex: (CoR2)2(HR)2 but flotation occurs through the formation of a surface active product which has the empirical formula CoR2. The effects of pH and of decanoic acid concentration on the three separation processes were also investigated and the results discussed. Good agreement was observed between the experimental precipitate flotation curves and the theoretical curve calculated from the data published for Co(II) hydrolysis. 相似文献
14.
A method is described for the flotation and determination of Mo(VI) in water at ng/ml levels. Mo(VI) is preconcentrated and separated by adsorbing colloid flotation employing aluminium(III) hydroxide as collector and sodium lauryl sulphate as surfactant at pH 5.3 ± 0.1. The molybdenum content in the froth is estimated by using the catalytic wave of Mo(VI) in the presence of nitrate by charging current compensated d.c. polarography (CCCDCP) or differential pulse polarography (DPP). The effect of variables such as pH, ionic strength, concentration of collector and surfactant, time of stirring and gas flow-rate on the recovery of Mo by flotation is reported. The effects of various cations and anions on the flotation and determination of Mo are studied. This method is employed for the determination of molybdenum in natural fresh water samples. 相似文献
15.
Reiner Goguel 《Fresenius' Journal of Analytical Chemistry》1990,336(4):311-315
Summary Oxygen stoichiometry is a critical parameter defining the Tc of cuprate superconductors (e.g. YBa2Cu3O7). On dissolution excess or deficiency of oxygen can be converted into shifts of the Fe(II)/Fe(III) concentration ratio of an aqueous solution. For small samples a solvent extraction technique for the separation of Fe(III) from Fe(II) was developed, to make use of the superior sensitivity of atomic spectrometry (AAS, ICP-AES). The system n-benzoylphenylhydroxylamine (BPHA)/CHCl3 was chosen because it is relatively inactive as a redox partner. Despite the catalytic effect of Cu(II) on the oxidation of Fe(II), oxidation blanks can be kept down at negligible levels. Less than 0.55% of residual Fe(II) is converted to Fe(III) during the extraction procedure (argon atmosphere). In the presence of air, oxidation levels are still practical (3%). Extraction is from 0.3 mol/l HBr providing excellent recovery of Fe(III) (e.g. 98.8%). All Fe(II), Y, Ba (including BaSO4 precipitate) and 99.4% of the Cu remain in the aqueous phase. Fe(III) is rapidly back-extracted into an aqueous phase by 6 mol/l HCl for dilution and aspiration into the flame or ICP. Recovery of Fe(III) after the two extraction steps is still 98.3%. 相似文献
16.
Summary The sorption of microamounts of gallium(III) on Fe(OH)3 and Fe2O3 precipitates was studied by using67Ga as radioactive indicator. The dependence of sorption of microamounts of gallium(III) on pH, sorbent concentration, and duration of the contact between gallium-(III) and Fe(OH)3 precipitate, was established. In the presence of sodium citrate the sorption of microamounts of gallium (III) on Fe2O3 markedly decreased. Iron(III) hydroxide and Fe2O3 precipitates are suitable collectors for the preconcentration of gallium (III) traces in solution.
Zusammenfassung Die Adsorption von Mikromengen Ga(III) an Niederschlägen von Fe(OH)3 und Fe2O3 wurde mit Hilfe von67Ga als radioaktivem Indikator untersucht. Die Abhängigkeit der Adsorption vom pH, von der Konzentration des Sorptionsmittels und von der Dauer des Kontakts zwischen Ga(III) und Fe(0H)3 wurde festgestellt. In Gegenwart von Na-Citrat wird die Sorption an Fe2O3 merklich geringer. Eisen (III)hydroxid- und Fe2O3-Niederschläge eignen sich als Kollektoren zur Anreicherung von Ga(III)-Spuren in einer Lösung.相似文献
17.
Sibel Yalçin 《Analytica chimica acta》2004,505(1):25-35
Chromium may exist in environmental waters as Cr(III) and Cr(IV), the latter being the toxic and carcinogenic form. Since atomic absorption spectrometry (AAS) and inductively coupled plasma atomic emission spectrometry can only yield information on total Cr concentration, a polymer resin bearing O,O-donor chelating groups such as the maleic acid-functionalized XAD(CO)CHCHCOOH resin was synthesized to selectively retain Cr(III) at pH 4.0-5.5. The dynamic breakthrough capacity of the resin for Cr(III) at pH 5.0 was 7.52 mg g−1, and the preconcentration factor extended to 250-300. Chromium(III) in the presence of 250-fold Cr(VI)—which was not retained—could be effectively preconcentrated on the NH4+-form of the resin and determined by AAS or diphenylcarbazide (DPC) spectrophotometry. When Cr(VI) was reduced to Cr(III) with Na2SO3 solution brought to pH 1 by the addition of 1 M H2SO4, and preconcentrated on the resin, total Cr could be determined. The developed method was validated with a blended coal sample CRM-1632. Since the adsorption behavior as a function of pH of possible interferent metal ions, e.g. Ni(II), Co(II), Cu(II), Cd(II), Zn(II), Pb(II) and Fe(III), was similar to that of Cr(III), selective elution of Cr(III) from the resin was realized using a mixture of 1 wt.% H2O2+1 M NH3. The eluate containing Cr as chromate could be directly analyzed by diphenyl carbazide spectrophotometry without any adverse effect from the common interferents of this method, i.e. Fe(III), Cu(II) Hg(II), VO3−, MoO42− and WO42−. Various synthetic waste solutions typical of electroplating bath effluents containing Cr, Cu, Ni, Zn, Na, Ca, cyanide (and chemical oxidation demand (COD), achieved by glucose addition) were subjected to pretreatment procedures such as hypochlorite oxidation (of cyanide) and catalytic oxidation (of COD) with peroxodisulfate. Chromium determination gave satisfactory results. The combined column preconcentration—selective elution—diphenylcarbazide spectrophotometric determination was also successfully applied to the determination of Cr in artificial and real seawater. 相似文献
18.
Magda Ali Akl 《Microchemical Journal》2003,75(3):199-209
Preconcentration, speciation and separation with solvent extraction of Fe(III) from samples of different origin, using methyl isobutyl ketone (MIBK) as a solvent and the sodium salt of 2-carboethoxy-1,3-indandione (CEIDNa) as a complexing agent for Fe(III), were studied. CEIDNa reacts with Fe(III) in the pH range 1.5–3.5 to produce a red colored complex of Fe(III)–CEIDNa (1:3 molar ratio) soluble in MIBK. The investigation includes a study of the characteristics that are essential for solvent extraction, spectrophotometric and flame atomic absorption spectrometric determination (AAS) of iron. A highly sensitive, selective and rapid spectrometric method is described for the trace analysis of iron(III) by CEIDNa. The complex formed obeys Beer's law from 0.06 to 1.8 mg l−1 with an optimum range. A single step extraction was efficiently used with a distribution ratio (D)=103.6. The extracted red colored (1:3) Fe–CEIDNa was measured spectrophotometrically at 500 nm with a molar absorptivity of 1.2×104 l mol−1 cm−1. In addition, the organic phase was directly aspirated to the flame for AAS determination and the signals related to Fe(III) concentration were recorded at 243.3 nm. The complexation of iron(III) with CEIDNa allows the separation of the analyte from alkali, alkaline earth and other elements, which are not complexed. The proposed preconcentration procedure was applied successfully to the determination of trace Fe(III) in soil, milk and natural water samples. 相似文献
19.
A highly sensitive and selective combined method of flotation followed by spectrophotometry/d.c. polarography for the determination of tungsten and tin ions in acid and alkaline waste waters and hydrometallurgical solutions is presented here. Both kinds of ions are coprecipitated in the analyte solution with zirconium hydroxide after addition of ZrOCl2 solution and ammonia. Afterwards, the collector precipitate is separated from the aqueous phase and preconcentrated by flotation for which sodium oleate and a frother are added. The precipitate is dissolved in a small amount of acid, with the organic reagents being destroyed by oxidation. The enrichment factor of the proposed technique is 100, with variations possible. Recovery is 94% for tungsten and 99% for tin. Spectrophotometry of the thiocyanate complex and d.c. polarography are applied as determination techniques for tungsten and tin, respectively. Detection limits attainable by this technique are 6 ng · ml–1 for tungsten and 5 ng · ml–1 for tin for the initial sample. 相似文献
20.
《Analytical letters》2012,45(9):643-651
Abstract Polarography with a sodium carbonate-oxalic acid supporting electrolyte was used to determine both Fe(II) and Fe(III) simultaneously in actual coal mine water samples. The average relative percent error was 2.2% for Fe(II) and 2.1% for Fe(III) over a range of 10 to 500 ppm. In actual mine water the Fe(II) content was highest where the mine water emerged. As the water moved down stream from the source of pollution Fe(II) decreased and Fe(III) concentration increased as Fe(II) was oxidized to Fe(III) by oxygen. This was accompanied by a decrease in pH. Further down the stream Fe(III) started to precipitate and then its concentration steadily decreased. 相似文献