II), Chromium Research Articles

Potentials of 3, 31, 41, 5, 7-pentahydroxyflavylium of Hibiscus rosa-sinensis L. (Malvaceae) flowers as ligand in the quantitative determination of Pb, Cd and Cr.

3, 31,41,5,7-Pentahydroxyflavylium chloride (cyanidin chloride) was extracted from the flowers of Hibiscus rosa-sinensis L. and blackberry fruits and the purity confirmed by co-chromatography with authentic marker on thin layer chromatography (TLC) and paper chromatography (PC). UV-Visible spectrophotometric determinations of the sample and its Pb (II), Cr (III) and Cd (II) complexes at various pH were carried out. The cyanidin sample absorbs at 530 and 540 nm in methanol and ethanol respectively. A Cyanidin-Pb (II) complex was formed at pH 4.2 (λmax = 555 nm, in methanol). A Cyanidin-Cr (III) complex was formed at pH 1.0 (λmax = 682 nm, methanol and ethanol) while a Cyanidin-Cd (II) complex was formed at pH 3.0 [λmax = 706 nm (methanol) and 679 nm (ethanol)]. All the metal-ligand complexes occur in the ratio of 1:2 and the molar absorptivities are 9.66 x 102, 8.77 x 102 and 9.77 x 102 L.mol-1.cm-1 for Pb, Cr and Cd respectively. Under optimum conditions, the absorbance of the complexes was found to increase linearly with increase in metal-ion concentrations, which corroborated with the correlation coefficient values. The linear range of the calibration graph was 0.1 – 0.5 mM for all the complexes. The results show that cyanidin could be used as a reagent for the spectrophotometric determination of Cr (III), Pb (II) and Cd (II) and by varying the pH, these metals could be determined simultaneously in solution. Key words: Cyanidin chloride, Hibiscus rosa-sinensis, metal - ligand complex, Lead (II), chromium (III), Cadmium (II), spectrophotometric assay.

Solvothermal synthesis of nanocrystalline zinc oxide doped with Mn2+, Ni2+, Co2+ and Cr3+ ions

ZnO nanopowders doped with Mn2+, Ni2+, Co2+ and Cr3+ ions have been synthesised for the first time using a solvothermal reaction with microwave heating. The nanopowders were produced from a solution of zinc acetate and manganese (II), chromium (III), nickel (II) and cobalt (II) acetates, using ethylene glycol as a solvent. The content of Ni2+, Co2+ and Cr3+ ions in the solution and in the solid phase were close to each other up to 5 mol%. The doping level of Mn2+ ions in the solid is about 50% of that in the solution. No phases or compounds other than ZnO were detected by X-ray diffraction with Mn2+, Co2+ and Ni2+ doping. With Cr3+ ions a small amount of chromium oxide was found. None of the powders displayed any luminescence after doping. The Mn2+-doped powder displayed a paramagnetic behaviour. ESR and magnetisation investigations have revealed that no clustering of Mn2+ ions occurred up to a doping level of 3.9 mol%. The average grain size of powders doped with Ni2+, Cr3+, Co2+ and Mn2+ for a 10 mol% ion content in the solution was about 20 nm and the grain size dispersion 30%. With increasing dopant content the grain size decreased. It appears that the solvothermal process employed allows relatively high doping levels of the transition metal ions to be achieved without any dopant clustering or oxide precipitation.

Metal inclusion in expanded clays

The possibility to include in expanded clay little amounts of metallic ions present in waste material, without significant influence on the environment, was investigated. In this article, known quantities of cadmium(II), lead(II), chromium(III), and chromium(VI) were added to a mixture of raw pit clay, adding a small amount of mineral oil. The resultant paste was heated at 1200°C, in conditions to provide the commercial product with the best characteristics of lightness. The obtained pellets were analyzed in two ways. A sample of expanded clay was crushed, added to with KNaCO3 and melted. The melted mass, after cooling, was dissolved in HCl or in water and analyzed. The composition of the raw pit clay was analyzed as a blank. In parallel, pellets were subjected to a leaching process and the eluate was analyzed for the added cations. The concentration of the metal ions in the leached water is negligible compared with that generally admitted in drinking water.

Comparative study of the biosorption of cadmium(II), chromium(III), and lead(II) by olive stone

AbstractThis research focuses on potential of using olive stone as a low‐cost biosorbent, for cadmium, chromium, and lead removal from aqueous solutions in a batch system as a function of pH, contact time, and temperature. Experimental data were tested in terms of biosorption kinetics using pseudo‐second‐order kinetic model. The results showed that the biosorption processes of the three metal ions followed well pseudo‐second‐order kinetics at 25, 40, and 60°C and for a metal initial concentration of 10 mg/L. The activation energy of biosorption (E) was determined as 7.09 kJ/mol for Cd(II), 12.39 kJ/mol for Cr(III), and 10.29 kJ/mol for Pb(II) indicating that the biosorption of these metal ions was taken place mainly by physical interactions. The equilibrium biosorption was also studied at these temperatures applying Sips isotherm model. Using the Sips constant, b, the thermodynamic parameters were calculated. The values of these parameters showed that the biosorption of Cd(II), Cr(III), and Pb(II) ions by olive stone was feasible and spontaneous and reflected the endothermic nature of the process for the removal of Cr(III) and Pb(II) except Cd(II). © 2008 American Institute of Chemical Engineers Environ Prog, 2008

Environmental Evaluation of Metals in Sediments and Dragonflies Due to Sugar Cane Cultivation in Neotropical Streams

The use of fertilizers, containing different metals ions such as lead(II), chromium(III), cadmium(II), copper(II) and zinc(II), in the soil, for sugar cane cultivation, may cause impacts on the hydric resources of the adjacent areas. The scope of this study was to evaluate the impacts of sugar cane cultivation based on metal concentrations in sediments and dragonflies (Odonata). The bioavailability of such metals was determined in ten Neotropical streams. Six streams were located on areas with sugar cane cultivation, without riparian vegetation (classified as impacted area) and four streams were located on forested areas (reference sites). The results showed that there are high concentrations of metals in the sediments and dragonflies in streams located on impacted areas. The contamination by metals of aquatic insects of terrestrial adult life cycle, as Odonata organisms, represents a dangerous link for the transference of metals to upper trophic levels, as fishes, reptiles, birds and mammals.

Multi-element coprecipitation for separation and enrichment of heavy metal ions for their flame atomic absorption spectrometric determinations

A preconcentration–separation technique for lead(II), cadmium(II), chromium(III), nickel(II) and manganese(II) ions has been established. The procedure is based on coprecipitation of these ions by the aid of Cu(II)-dibenzyldithiocarbamate precipitate. The precipitate was dissolved in 0.5 mL of concentrated HNO 3, and made up to 5 mL with distilled water. The heavy metals were determined by flame atomic absorption spectrometer. The effects of analytical parameters like pH, amounts of reagents, sample volume, etc. on the recoveries of heavy metals were investigated. The influences of matrix ions were also examined. The detection limits for the heavy metals based on 3 sigma ( N = 21) were found in the range of 0.34–0.87 μg L −1. In order to validate the proposed method, two certified reference materials of NIST SRM 2711 Montana soil and NIST SRM 1515 Apple leaves were analyzed with satisfactory results. The proposed method was applied for the determination of lead, cadmium, chromium, nickel and manganese in environmental samples.

Identification of homemade inorganic explosives by ion chromatographic analysis of post-blast residues

Anions and cations of interest for the post-blast identification of homemade inorganic explosives were separated and detected by ion chromatographic (IC) methods. The ionic analytes used for identification of explosives in this study comprised 18 anions (acetate, benzoate, bromate, carbonate, chlorate, chloride, chlorite, chromate, cyanate, fluoride, formate, nitrate, nitrite, perchlorate, phosphate, sulfate, thiocyanate and thiosulfate) and 12 cations (ammonium, barium(II), calcium(II), chromium(III), ethylammonium, magnesium(II), manganese(II), methylammonium, potassium(I), sodium(I), strontium(II), and zinc(II)). Two IC separations are presented, using suppressed IC on a Dionex AS20 column with potassium hydroxide as eluent for anions, and non-suppressed IC for cations using a Dionex SCS 1 column with oxalic acid/acetonitrile as eluent. Conductivity detection was used in both cases. Detection limits for anions were in the range 2–27.4 ppb, and for cations were in the range 13–115 ppb. These methods allowed the explosive residue ions to be identified and separated from background ions likely to be present in the environment. Linearity (over a calibration range of 0.05–50 ppm) was evaluated for both methods, with r 2 values ranging from 0.9889 to 1.000. Reproducibility over 10 consecutive injections of a 5 ppm standard ranged from 0.01 to 0.22% relative standard deviation (RSD) for retention time and 0.29 to 2.16%RSD for peak area. The anion and cation separations were performed simultaneously by using two Dionex ICS-2000 chromatographs served by a single autoinjector. The efficacy of the developed methods was demonstrated by analysis of residue samples taken from witness plates and soils collected following the controlled detonation of a series of different inorganic homemade explosives. The results obtained were also confirmed by parallel analysis of the same samples by capillary electrophoresis (CE) with excellent agreement being obtained.

Biosorption of lead(II), chromium(III) and copper(II) by R. opacus: Equilibrium and kinetic studies

Micro-organisms and microbial products can be highly efficient to uptake soluble and particulate forms of metals, particularly from dilute solutions. The aim of this work was to evaluate the fundamental aspects of the biosorption of Pb(II), Cr(III) and Cu(II) metal species using Rhodococcus opacus strain. Zeta potential studies and adsorption experiments were carried out in order to evaluate the sorption metals uptake and the possible interaction mechanisms between the metal species and the surface cell wall. The electrophoretic studies showed that the presence of the metal species affected the zeta potential profiles. Moreover, the equilibrium biomass – metals systems followed the Langmuir isotherm model and the pseudo-second order kinetic model. The influence of Cr(III) and Cu(II) on Pb(II) biosorption capacity in binary and ternary systems was evaluated and biosorption capacity of the Pb(II) ions was found to be reduced by the presence of the other competing metal ions. The nature of possible cell–metal ions interactions was also evaluated by FT-IR and SEM/EDS analysis. These examinations indicated the involvement of –COOH, –OH and –NH groups in the biosorption process.

Biosorption Characteristics of Copper (II), Chromium (III), Nickel (II), and Lead (II) from Aqueous Solutions by Chara sp. and Cladophora sp

The aim of this research was to expose individual removals of copper, chromium, nickel, and lead from aqueous solutions via biosorption using nonliving algae species, Chara sp. and Cladophora sp. Optimum pH values for biosorption of copper (II), chromium (III), nickel (II), and lead (II) from aqueous solutions were determined to be 6, 7, 7, and 3 for Cladophora sp. and 5, 3, 5, and 4 for Chara sp. respectively. Maximum adsorption capacities of Chara sp. [10.54 for chromium (III) and 61.72 for lead (II)] and Cladophora sp. [6.59 for chromium (III) and 16.75 and 23.25 for lead (II)] for chromium (III) and lead (II) are similar. On the other hand, copper (II) and nickel (II) biosorption capacity of Cladophora sp. [14.28 for copper (II) and 16.75 for nickel (II)] is greater than Chara sp. [6.506 for copper (II) and 11.76 for nickel (II)]. Significantly high correlation coefficients indicated for the Langmuir adsorption isotherm models can be used to describe the equilibrium behavior of copper, chromium, nickel, and lead adsorption onto Cladophora sp. and Chara sp.

REMOVAL OF METAL IONS WITH IMPACT ON THE ENVIRONMENT BY WATER-INSOLUBLE FUNCTIONAL COPOLYMERS: SYNTHESIS AND METAL ION UPTAKE PROPERTIES

The crosslinked resins poly(4-acryloylmorpholine-co-4-vinyl pyridine) P(AMo- VPy), poly(N-(3-dimethylamino)propylmethacrylamide-co-4-vinyl pyridine) P(NDAPA-VPy), and poly((3-dimethylamino)propylacrylate-co-4-vinyl pyridine) P(DAPA-VPy) were obtained by radical polymerization. The resins were completely insoluble in water. The uptake metal ion properties are studied by batch equilibrium procedure for the following metal ions: silver(I), copper(II), cadmium(II), zinc(II), lead(II), mercury(II), chromium(III), and aluminum(III). P(AMo-VPy) resin shows a lower metal ion affinity than P(DAPA-VPy), except for Hg(II) which is retained in almost 100 % at pH 2. At pH 5, the resin shows the higher affinity for Ag(I) (80%) and Cu(II) (60%) but it is very low for Zn(II) and Cr(III). The polymer ligand metal ion equilibrium is achieved during the first 20 min. By changing the pH is possible to remove between 50 % and 70 % of Cd(II) and Cu(II) ions by using (1 M, 4 M) HClO4 and (1 M, 4 M) HNO3

Pseudomonas aeruginosa immobilized multiwalled carbon nanotubes as biosorbent for heavy metal ions

Pseudomonas aeruginosa immobilized multiwalled carbon nanotubes has been used as biosorbent for the solid phase extraction of some heavy metal ions in environmental samples. Cobalt(II), cadmium(II), lead(II), manganese(II), chromium(III) and nickel(II) ions have been selected as analytes for the presented study, due to their important negative and positive roles in human life. In order to investigate quantitative biosorption conditions of the analytes, the influences of pH of the aqueous solution, eluent type, eluent volume, samples volume, etc. were examined. The effects of alkaline, earth alkaline and some transitions metals on the biosorption of analyte ions on P. aeruginosa immobilized multiwalled carbon nanotubes were also investigated. The presented biosorption procedure was applied to the determination of analytes in tomato leaves, bovine liver, boiled wheat, canned fish, black tea, lichen and natural water samples.

Bacillus thuringiensis var. israelensis immobilized on Chromosorb 101: A new solid phase extractant for preconcentration of heavy metal ions in environmental samples

Bacillus thuringiensis var. israelensis immobilized on Chromosorb 101 that is a new solid phase extractor has been presented at this work for the preconcentration and separation of cadmium(II), lead(II), manganese(II), chromium(III), nickel(II) and cobalt(II) in environmental samples. The analytical parameters including pH of aqueous solutions, sample volume, eluent types, etc. were investigated for the quantitative recoveries of the analytes. The influences of the some metal ions as concomitant were investigated. Under the optimized conditions, the detection limits by 3 σ for analyte ions were in the range of 0.37–2.85 μg L −1. The accuracy of the developed procedure was confirmed by IAEA 336 Lichen and NIST SRM 1573a Tomato leaves certified reference materials. The method was also applied successfully to the determination of analytes in microwave digested red wine, rice and canned fish samples and sea water, spring water and urine samples.

A novel multi-element coprecipitation technique for separation and enrichment of metal ions in environmental samples

A multi-element preconcentration–separation technique for heavy metal ions in environmental samples has been established. The procedure is based on coprecipitation of gold(III), bismuth(III), cobalt(II), chromium(III), iron(III), manganese(II), nickel(II), lead(II), thorium(IV) and uranium(VI) ions by the aid of Cu(II)–9-phenyl-3-fluorone precipitate. The Cu(II)–9-phenyl-3-fluorone precipitate was dissolved by the addition 1.0 mL of concentrated HNO 3 and then the solution was completed to 5 mL with distilled water. Iron, lead, cobalt, chromium, manganese and nickel levels in the final solution were determined by flame atomic absorption spectrometer, while gold, bismuth, uranium and thorium were determined by inductively coupled plasma mass spectrometer. The optimal conditions are pH 7, amounts of 9-phenyl-3-fluorone: 5 mg and amounts of Cu(II): 1 mg. The effects of concomitant ions as matrix were also examined. The preconcentration factor was 30. Gold(III), bismuth(III), chromium(III), iron(III), lead(II) and thorium(IV) were quantitatively recovered from the real samples. The detection limits for the analyte elements based on 3 sigma ( n = 15) were in the range of 0.05–12.9 μg L −1. The validation of the presented procedure was checked by the analysis of two certified reference materials (Montana I Soil (NIST-SRM 2710) and Lake Sediment (IAEA-SL-1)). The procedure was successfully applied to some environmental samples including water and sediments.

Heavy metal removal from waste waters by ion flotation

Flotation studies were carried out to investigate the removal of heavy metals such as copper (II), zinc (II), chromium (III) and silver (I) from waste waters. Various parameters such as pH, collector and frother concentrations and airflow rate were tested to determine the optimum flotation conditions. Sodium dodecyl sulfate and hexadecyltrimethyl ammonium bromide were used as collectors. Ethanol and methyl isobutyl carbinol (MIBC) were used as frothers. Metal removal reached about 74% under optimum conditions at low pH. At basic pH it became as high as 90%, probably due to the contribution from the flotation of metal precipitates.

Rapid In Vitro Screening of Drug–Metal Ion Interactions

ABSTRACTThe toxic side effects of synthetic drugs may, in part, be arising due to their interactions with essential metal ions, especially when the metal ions are administered along with the drug as mineral supplements. In this paper we report the feasibility of establishing such drug–metal ion interactions through in vitro spectrophotometric studies, which are rapid and can be used for routine screening prior to clinical studies. The interaction of the drugs levothyroxine and ranitidine with eight metal ions, copper(II), chromium(III), molybdenum(VI), magnesium(II), calcium(II), iron(II), manganese(II), and zinc(II), commonly used in mineral supplements, was verified through in vitro UV-visible spectrophotometric studies. The experiments were carried out at the physiological pH values 1.5, 7.4, and 8.0 and the concentrations of the drugs and mineral supplements used were comparable to those in their usual doses. These studies indicated interaction between ranitidine and calcium(II), magnesium(II), and iron(II) ions and between levothyroxine and copper(II) and iron(II) ions. A comparison of the results with those reported from clinical studies demonstrated the efficacy of this method.

Synthesis of water‐insoluble functional copolymers containing amide, amine, and carboxylic acid groups and their metal‐ion‐uptake properties

AbstractThe crosslinked poly[N‐(3‐dimethylamino)propylmethacrylamide] [P(NDAPA)] and poly[N‐(3‐dimethylamino)propylmethacrylamide‐co‐acrylic acid] [P(NDAPA‐co‐AA)] were synthesized by radical polymerization. The resins were completely insoluble in water. The metal‐ion‐uptake properties were studied by a batch equilibrium procedure for the following metal ions: silver(I), copper(II), cadmium(II), zinc(II), lead(II), mercury(II), chromium(III), and aluminum(III). The P(NDAPA‐co‐AA) resin showed a lower metal‐ion affinity than P(NDAPA), except for Hg(II), which was retained at 71% at pH 2. At pH 5, the resin showed a higher affinity for Pb(II) (80%) and Cu(II) (60%), but its affinity was very low for Zn(II) and Cr(III). The polymer ligand–metal‐ion equilibrium was achieved during the first 20 min. By changing the pH, we found it possible to remove between 60 and 70% of Cd(II) and Zn(II) ions with (1M, 4M) HClO4 and (1M, 4M) HNO3. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5232–5239, 2006

Spinel-type HgCr2O4from single-crystal data

The crystal structure of mercury(II) chromium(III) tetroxide has been redetermined from a single crystal grown from an HgO–CrO3 mixture at 743 K in an evacuated silica ampoule. The present investigation confirms the previous study, which was based on powder data [Wessels, Czekalla & Jeitschko (1998). Mater. Res. Bull. 33, 95–191], but with higher precision and with all displacement parameters refined anisotropically. HgCr2O4 adopts the normal 2–3-spinel structure, with mercury in one-eighth of the tetra­hedral and chromium in one-half of the octa­hedral voids of the cubic closed-packed O atoms.

Rapid Coprecipitation Technique with Hybrid Hydroxide System Using Ytterbium(III), Gallium(III), and Magnesium(II) for Simultaneous Concentration of 13 Elements in Concentrated Salt Solution Prior to Their Inductively Coupled Plasma Atomic Emission Spectrometric Determination

Abstract Beryllium(II), chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), zinc(II), arsenic(V), selenium(IV), cadmium(II), antimony(III), and lead(II) ions in concentrated salt solutions, such as seawater or sodium chloride and sulfate solutions, were collected quantitatively by coprecipitation with hydroxides of ytterbium(III), gallium(III), and magnesium(II). In this method, a rapid coprecipitation technique combined with internal standardization was applied to simplify the operation; yttrium was used as an internal standard. The 13 elements collected were readily determined by inductively coupled plasma atomic emission spectrometry using internal standardization. The detection limits (3σ, n = 10) were in the range of 0.003 μg (for beryllium(II)) to 0.13 μg (for zinc(II)) in the initial sample solution (up to 150 mL). The proposed method was applied to the analyses of some commercially available salts and an effluent as well as the certified reference materials; the elements ranging from 0.03–0.14 μg g−1 in the salts, 0.004–0.041 mg L−1 in the effluent, or 0.006–0.30 mg L−1 in the certified reference materials could be determined with the relative standard deviation of 7–33, 0.3–3, or 2–17%, respectively. The time required for the preconcentration was approximately 20 min.

Celtek clay as sorbent for separation–preconcentration of metal ions from environmental samples

The sorption conditions including pH of the aqueous solution, sample volume, etc., on Celtek clay of copper(II), cadmium(II), lead(II), chromium(III), nickel(II) and cobalt(II) ions from environmental samples has been studied. The effects of electrolytes as matrix on the preconcentration were also investigated with the recoveries >95%. The 3 sigma detection limits for copper, cadmium, lead, chromium, nickel and cobalt ions were found to be 0.25, 0.32, 0.73, 0.45, 0.50 and 0.41 μg/l, respectively. The relative standard deviation was <10% for the determination of analytes. The procedure was validated by analysis of a NRCC-SLRS 4 Riverine Water, SRM 1573a Tomato leaves and IAEA 336 Lichen standard reference materials. The developed method was successively utilized for the determination of Cu(II), Cd(II), Pb(II), Cr(III), Ni(II) and Co(II) in various samples including natural waters, wheat and human hair by flame atomic absorption spectrometry (FAAS) with satisfactorily results (recoveries > 95% and R.S.D.'s < 10%).

Chemiluminescent determination of vanadium(IV) using a cinchomeronic hydrazide–H 2O 2 system and flow injection analysis

This paper proposes a new chemiluminescent flow injection analysis (FIA) method for the determination of vanadium(IV) ions in aqueous media. The method is based on the chemiluminescent reaction that occurs between cinchomeronic hydrazide (CH) and hydrogen peroxide in a strongly alkaline medium, in which vanadium(IV) acts as a catalyst. The chemical and physical variables involved in the flow injection system are optimised using a modified simplex method. Vanadium ions can be detected in the 0.08 and 1.00 μg mL −1 range; the detection limit for a signal-to-noise ratio of 3 is 0.08 μg mL −1. Great variations in the quantum yield were observed when cobalt(II), chromium(III), copper(II) and/or nickel(II) were present in the reaction medium. The proposed method is selective and simple, and can be successfully used to analyse water samples without the need for separation or preconcentration processes.