Water quality,natural chemical weathering and ecological risk assessment of the contaminated area of vanadium ore in Yinhua River,China:Evidence from major ions and trace elements

There are abundant vanadium ores in the Cambrian strata in southern Shaanxi,China.Many years of mining activities and surface leaching have polluted the surface water to a certain extent,but the researches on the water quality characteristics and pollution degree are relatively weak.This contribution was organized to investigate the surface water quality by general parameters,including TDS,Eh,pH,DO,TOC,COD,and EC,in the vanadium ore belt(Yinhua River basin).Major ions were determined to detect the water type and natural chemical weathering,while trace elements were used to illustrate their geochemical characteristics and ecological risk assessment of heavy metals.The study found that the surface water was weakly alkaline and mainly dominated from normal to pool grade.The particle size with1000–10,000 nm of suspended particles was the main carrier of organic matter.The concentration of HCO_(3)^(-)and SO_(4)^(2-)in the anions and Ca^(2+)and Mg^(2+)ions in the cations were relatively high,and the water type was Ca-Mg-HCO_(3)-SO_(4) type.Rock weathering had a great influence on surface water,and the weathering products were mainly silicate and carbonate.Compared with the Type river,the contents of V elements showed an obvious positive anomaly,which may be affected by mining activities of vanadium ore and the annual leaching of the tailings pond.As and Cd in the surface water was polluted seriously.The integrated pollution index suggested that the surface water pollution was serious,and the main stream was more serious with the increasing tailings ponds.

Determination of Trace Vanadium (Ⅴ) in Seawater and Fresh Water by the Catalytic Kinetic Spectrophotometric Method

A new kinetic spectrophotometric method has been developed for the determination of vanadium (Ⅴ).The method is based on the catalytic effect of vanadium (Ⅴ) on the oxidation of weak acid brilliant blue dye (RAWL) by KBrO3 using the citric acid as activation reagent.The obtained optimum conditions are:c (RAWL)=1×10-4 molL-1, c (KBrO3)=3×10-2 molL-1, c (citric acid)= 9×10-3 molL-1, pH=2.50, the reaction time being 7.0 min and the temperature being 25.0℃.Under the optimum conditions, the pro-posed method allows the determination of vanadium (Ⅴ) in the range of 0?70.0 ng mL-1 and the detection limit is down to 0.407 ng mL-1.For standard vanadium (Ⅴ) solution determination, the recovery efficiency is in the range of 98.5%?102% and the RSD ranges from 0.76%?1.25%.Moreover, it is demonstrated that most cations and anions do not interfere with the determination of vanadium (Ⅴ) under the analytical condition.The new method was successfully applied in the determination of vanadium (Ⅴ) in fresh water and seawater samples with satisfactory results.Vanadium (Ⅴ) in the seawater samples from Qingdao offshore was determined using the method and the distribution of vanadium (Ⅴ) was mapped.Compared with other instrumental analytical methods, the proposed method shows good selectivity, sensitivity, simplicity, lower cost and rapidity.It can be employed on shipboard easily.

Solvent extraction of vanadium from sulfuric acid solution

The behaviour of vanadium（V） extracted from sulfuric acid solution was investigated using Cyanex 923 as an extractant. The effects of the concentration of Cyanex 923 and the pH of the solution were studied. The extraction of vanadium（V） increases with the increase of Cyanex 923 concentration and shaking time. Cyanex 923 can extract vanadium（V） from sulfuric acid solution at low pH conditions, and the best pH conditions for extraction of vanadium（V） are at pH 1.0-2.0. The species extracted into the organic phase is VO2HSO4 with one molecule of Cyanex 923. Equilibrium studies were used to assess the extraction efficiency of vanadium（V） recovery from the sulfuric acid solution.

A new process of extracting vanadium from stone coal

A new process of extracting vanadium from the stone coal vanadium ore in Fangshankou, Dtmhuang area of Gansu Province, China was introduced. Various leaching experiments were carried out, and the results show that the vanadium ore in Fangshankou is difficult to process due to its high consumption of acid and the high leaching rate of impurities. However, the leaching rate can be up to 80% and the content of V2O5 in the residue can be between 0.22%-0.25% in the process of ore fme grinding→oxidation roasting→mixing and ripening→aqueous leaching→P2O4 solvent extraction→sulfuric acid stripping→oxidation and precipitation→decomposition by heat. Also, the quality of flaky V205 produced by this process can meet the requirements of GB3283--87. The total leaching rate of vanadium is 70%. Also, three types of wastes are easy to treat. The vanadium extraction process is better in relation to the aspect of environmental protection than the sodium method.

Hydrothermal synthesis of vanadium oxide nanotubes by a facile route

Vanadium oxide nanotubes were synthesized by hydrothermal treatment from V2O5·nH2O sols as precursor and dodecylamine as structure-directing template. The morphology and structure of the nanotubes were characterized by SEM, TEM, XRD, TG-DTA and FTIR. The experimental results reveal that the duration of the hydrothermal treatment is of importance for obtaining VOx-NTs which have a layered structure. TG-DTA study indicates that V5+ cations in nanotubes are partially reduced to V4+ cations. The results from FTIR spectra indicate the difference in V-O vibrations between before and after hydrothermal treatment. From the results, it suggests that during hydrothermal treatment, the rearrangement of the vanadium oxide structure leads to the formation of VOx nanotubes from lamellar structure because of the presence of V4+ species.

Effect of cooling rate on morphology and type of vanadium-containing phases in Al-10V master alloy

Effects of cooling rates on the morphology, sizes and species of primary vanadium-containing phases in Al-10V master alloys were investigated. The results show that the primary vanadium-containing phases with different morphologies and compositions present in Al-10V master alloys at different cooling rates with the pouring temperature of 1,170 °C. When the Al-10V master alloy is solidified in the refractory mold at a cooling rate of 2 °C·s-1, the vanadium-containing phases are mainly plate-like Al10V phases, with the average size of 100.0 μm in the center and 93.2 μm at the edge of the ingot. When the master alloy is solidified in the graphite mold at a cooling rate of 24.3 °C·s-1, the primary vanadium-containing phases are dendritic Al3V phases, with the average length of 297.0 μm for the first dendrite in the center and 275.0 μm at the edge of the ingot. The secondary dendrite arm spacing (SDAS) is 9.5 μm in the center and 9.3 μm at the edge of the ingot, respectively. When the solidification is carried out in the copper mould at a cooling rate of 45.7 °C·s-1, the primary vanadium-containing phases are also Al3V phases but with smaller size, compared with that prepared at the cooling rate of 24.3 °C·s-1. As a result, the average length is 190.0 μm for the first dendrite in the center and 150.0 μm at the edge of the ingot. The SDAS is 9.8 μm in the center and 4.4 μm at the edge of the ingot, respectively.

The occurrence state of vanadium in the black shale-hosted vanadium deposits in Shangling of Guangxi Province, China

The Shangling vanadium deposit, which occurs in the Lower Devonian Tangding formation black rock series strata, has V2O5 reserves of more than 1.5 million tons and prospective reserves of more than 2 million tons. Preliminary studies on the occurrence state of vanadium(V) in this deposit have been conducted by artificial heavy minerals concentrates, leaching experiments, scanning and transmission electron microscopy and X-ray powder diffraction.These experiments have revealed no independent vanadium mineral occurrences in the Shangling vanadium deposit and the percentages of water-soluble vanadium, hydrochloric acid soluble vanadium and HF soluble vanadium were1.93 %, 21.42 % and 76.47 %, respectively. Based on our data and earlier research, we estimate that the valences state of V absorbed onto the surface of organic matter or clastic particles are +5 and +4, accounting for 10.00 % and13.35 % of the total amount of V, respectively and the valences state of V that exist in the octahedral crystal lattice of authigenic illite include +3 and +4, accounting for71.64 % and 4.83 % of the total amount of V, respectively.By calculating the correlation between the total organic carbon and V, we infer that after deposition and before entering the crystal lattice of illite, V occurs in the form of humate complex or is adsorbed by organic matter. About4.24 % of the Al is in the octahedral crystal lattice of illite,which was replaced by the vanadium under the metallogenic environments of Shanglin.

Catalytic Oxidative Desulfurization of Gasoline Using Vanadium(V)-substituted Polyoxometalate/H_2O_2/Ionic Liquid Emulsion System

Aiming at deep desulfurization of gasoline,three amphiphilic catalysts [C18H37N(CH3)3]3+x [PMo12-xVxO40](x=1,2,or 3) were prepared and characterized.The amphiphilic vanadium(V)-substituted polyoxometalates were dissolved in water-immiscible ionic liquid([Bmim]PF6),forming a H2O2-in-[Bmim]PF6 emulsion desulfurization system with 30 m% H2O2 serving as the oxidant.The catalytic oxidation of sulfur-containing model oil has been studied in detail under various reaction conditions using this system.The ionic liquid emulsion system showed high catalytic oxidative activity in the treatment of commodity gasoline.Furthermore,the mechanism of catalytic oxidative desulfurization was also elaborated.

Syntheses,Structures and Characterizations of Two New Vanadium(V) Complexes:[PyH][V^VO_2(C_(14)H_9N_2O_3Br)] and [V^VO(C_(14)H_9N_2O_3Br)(OCH_3)]

The new oxovanadium(V)complex,[PyH][VO2(L)]1(salicyladehyde 5-bromo salicyloylhydrazone is abbreviated as H2L;Hpy is protonated pyridine)was obtained from a refluxed solution of VOSO4 and H2L in acetonitrile-methanol-pyridine.Similarly,another new complex,[VO(L)(OCH3)]2 was synthesized by refluxing VOSO4 and H2L in methanol-pyridine.Crystal data for 1:C19H15N3O5BrV,Mr=496.2,monoclinic,P21/n,a=7.1885(3),b=9.2718(3),c=28.803(1)A,β=96.185(1)°,Z=4and V=1908.6(1)A^3;for 2:C15H12N2O5BrV,Mr=431.1,monoclinic ,P21/n,a=12.202(2),b=8.045(2),c=16.604(3)A,β=101.29(3)°,Z=4 and V=1598.4(2)A^3.The structures of 1 and 2 have been determined by X-ray analyses and reveal that the coordination environments of V atoms in both complexes are of square-based pyramid.Three of the four based donor atoms are from the tridentate“ONO”donor ligand while the fourth is one terminal oxygen atom with the V(1)-O(3)distance 1.646(4)Afor 1 and one-OCH3 group with the V(1)-O(3) distance 1.753(3)Afor 2.The V(1)-O(4) terminals occupy the axial sites in both cases.The complexes are also characterized by IR and ^1HNMR spectroscopies.

KINETICS OF POLYMERIZATION OF ACRYLONITRILE INITIATED BY VANADIUM(V)-THIOUREA REDOX SYSTEM

The kinetics of polymerization of acrylonitrile (AN) initiated by quinquevalent vanadium (V^(5+))-thiourea (TU) redox system has been investigated in aqueous nitric acid in the temperature range from 30 to 50℃. The polymerization rate (R_p) can be expressed as follows: In the copolymerization of acryionitrile with methyl acrylate (MA), the reactivity ratios were found to be 1.0 and 1.1, respectively. The experimental observations suggest that the initiating species is probably a complex consisting of a central ion of Lewis acid-VO_2^+ and the ligands of Lewis bases-acrylonitrile, thiourea, and nitrate anions, while the initiating system in lower concentration, the polymerization of acrylonitrile does not occur if the thiourea is acidified prior to its reaction with quinquevalent vanadium. This indicates that the primary radicals (or the monomeric radicals in the present article) are produced by associated thiourea rather than isothlourea.

Synthesis, Crystal Structure and Properties of a Novel Vanadium(Ⅴ) Oxoperoxo Complex Incorporating a Tridentate Hydrazone Ligand

A novel vanadium（V） oxoperoxo complex [VOO2（APTCH）（CH3OH）] （HAPTCH = 2-acetylpyridine thiophene-2-carboxylic hydrazone） has been synthesized and characterized by IR, TGA and X-ray single-crystal structure determination. The complex crystallizes in the monoclinic system, space group P21/c with a = 11.232（2）, b = 10.762（2）, c = 112.613（3）, β = 99.44（3）°, V = 1504.1（5）3, Dc = 1.657 g·cm-3, Z = 4, F（000） = 768, μ = 0.827 mm-1, the final R = 0.0392 and wR = 0.1073 for 2266 observed reflections with I 〉 2σ（I）. Single-crystal X-ray diffraction studies reveal that the vanadium（V） is coordinated by a tridentate ligand, methanol molecule and peroxo group to form a pentagonal-bipyramidal geometry. The crystal structure is stabilized by intermolecular hydrogen bonds of O-H···N and C-H···O.

Determination and Quantification of Vanadium(V) in Environmental Samples Using Chemically Modified Chitosan Sorbent

The application of biopolymers such as chitosan is one of the emerging sorption methods for the removal of metal ions, even at low concentrations. A rapid, sensitive and selected method is de- scribed for preconcentrative determination of vanadium(V) using the synthesized 3-Hydroxyben- zaldehyde-4 Amino antipyrine (HBAP), which was chemically immobilized on chitosan. This is easy to prepare in comparison to many other sorbents. The synthesized sorbent material was se- lective to vanadium(V) within a better response time of 30 min. The method was selective in presence of other foreign ions like Cl-, F-, , , Na+, Ca2+, Zn2+, Fe3+, Fe2+, Cu2+, Cr3+, EDTA, Mn2+, Co2+ and Ni2+. The calibration plots were linear over the concentration range of 0.5 μg·L-1 to 7 μg·L-1 of vanadium(V). These values are 100 times lower than by the direct determination of vanadium by FAAS. The developed procedure was reproducible with a relative standard deviation of 2.84%. The developed sorbent was successfully applied for the determination of vanadium(V) in real water and soil samples. Unlike most preconcentration procedures, the present enrichment method allowed for a rapid and reliable determination of vanadium(V) in environmental samples by the simple and routinely available flame atomic absorption spectrometry technique.

SYNTHESIS AND STRUCTURE OF A LINEAR TRIVANADIUM COMPOUND(Ph_4P)[V_3(OC_6H_4S-o)_6]-SIMULATION OF THE VANADIUM SITE OF ALTERNATIVE NITROGENASE

Compound(Ph_4P)[V_3MP_6](MPH_2=o-HOC_6H_4SH)was obtained by reaction of VCl_3 and Na_2MP in ethanol in the presence of Ph_4PBr.It is triclinic and crystallizes in space group P1,fw=1237.3,a=14.127(4), b=14.342(4),c=15.878(4);α=65.08(2),β=73.09(2),T=78.68(2)°;V=2781.3~3, Z=2,d_c=1.48 g/cm^3.Final R factor is 0.063.The three vanadium atoms are linearly arranged and bridged by the oxygen atoms and terminally chelated by the thiolato-atoms of the six MP^2-ligands in pseudo-S_6 symmetry.

THE ELECTROCHEMICAL BEHAVIOUR OF THE NEW VANADIUM BRONZE (Li_3V_5O_(15)) CATHODE IN SECONDARY LITHIUM BATTERY

A new kind of vanadium bronze with rich lithium (Li_5V_5O_(15))was prepared from Li_2CO_3 and V_2O_5 at 680℃ for 24 hrs. The charge and discharge curves of bronze electrode were determined in organic electrolyte. One mole of this material could be incorporated up to 4 mole lithium at 0.2mA/cm^2 and 1.0V cut-off voltage, corresponding capacity about 340Ah/kg. Compared with the cell of Li/Li_(1+x)V_3O_5 the cell of Li/new bronze had higher capacity, smoother discberge curve, but lower plateau voltage (about 1.8V). The cycling behaviour of this material was good. The electrode insertion reaction was controlled by the lithium diffusion process in the bronze. This new bronze could be used for low voltage rechargeable lithium battery.

PREPARATION OF V_2O_3 BY THERMAL DECOMPOSITION OF HYDRAZINE-CONTAINING VANADIUM SALT

A new method of preparing V_2O_3 by thermal decomposition from hydrazine-containing vanadium salt was described. The process was investigated by thermal analysis (TG and DSC) and the thermally decomposed product was studied by S.E.M., chemical analysis and X-ray diffraction. The result indicated that the product obtained in this way was V_2O_3.

Application of Nanometer-Size Titanium Dioxide in Extreme-Trace V(Ⅴ) Analysis

The adsorption properties of nanometer-size TiO2 for V（Ⅴ ） were studied. The adsorption rate could reach above 99~ when the pH values were at the range of 4 10. The adsorption balance time was 10 min , the saturation capacity of adsorption of nanometer-size TiO2 to V（Ⅴ） was 6.43 mg per gram. Using 2 mL 1.5 mol · L^-1 NaOH as elution, we found the elution rate could reach 95%. A novel method of extreme-trace V（Ⅴ ） preconeentration with nanometer-size titanium dioxide and determination by graphite furnace atomic absorption spectroscopy （GFAAS） was advanced. The detection limit（3σ）of the method was 0.61μg ·L^-1 , and the relative standard deviation was 8.1% （n=6） of 2.5μg ·L-^1 V（Ⅴ）. Environmental samples experiments were also conducted to test the feasibility of the method, and it came out that the recovery rates were between 91.2% and 102.0%.

The petrogenesis of modern and ophiolitic lavas reconsidered:Ti-V and Nb-Th

Tectonic discrimination diagrams are a key tool for understanding ancient volcanic rock origins.In this contribution we compile over 15,000 whole rock compositions to re-evaluate the Ti-V discrimination diagram and compare it to another commonly used tool,the Nb/Yb-Th/Yb diagram.We have reformulated the Ti-V diagram into a log-log plot to distinguish samples more clearly at lower concentrations.The compilation shows that MORB are dominated by Ti/V=20-43,whereas juvenile arc tholeiites and boninites are characterized by Ti/V<20 generally,although there is minor overlap at the boundary(Ti/V=20-22).Plume-related volcanic rocks(ocean island basalts,oceanic plateaux,and continental flood basalts)generally have Ti/V>43,although there may be significant overlap with MORB-like ratios for ridgecentered OIB and for some oceanic plateaux.About 56%of alkaline OIB have Ti/V>70.Back-arc basins are dominantly MORB-like.Melt models show that MORB and juvenile arc volcanics most likely formed under different fO;conditions,but are permissive of similar fO_(2)if the arc rocks form by much higher melt fractions.The Nb/Yb vs.Th/Yb plot clearly distinguishes most oceanic basalts(MORB,plateaux,OIB)from subduction-related volcanic rocks(boninite,juvenile arc tholeiite,calc-alkaline)and from flood basalts.We propose here a new two-proxy diagram of Ti/V vs.Th/Nb,which incorporates the advantages of both.

一株钒还原菌的分离鉴定及V(V)还原机理研究

从钒(V)污染土壤中筛选出一株对钒具有还原能力的细菌,探讨不同V(V)浓度、接种量、pH值条件对菌株还原V(V)的影响,研究菌株胞外、胞内还原V(V)的过程及酶活性变化,解析菌株对V(V)的还原机制.结果表明,筛选菌株NC1-2鉴定为一株神户肠杆菌(Enterobacter kobei).该菌株在160mg/L V(V)下培养7d时,V(V)还原率达96.29%;增加接菌量能加快V(V)还原;pH值8.0时菌株对V(V)的还原效果最佳.降低细胞膜通透性,V(V)还原率从71.2%提高至75.0%.不同亚细胞组分对V(V)的还原存在差异,胞外分泌物及细胞质组分对V(V)的还原率分别为41.71%和80.17%,细胞膜组分未发生V(V)还原.菌株还原V(V)过程中,亚硝酸还原酶(NIR)活性和还原型烟酰胺腺嘌呤二核苷酸(NADH)含量均有不同程度的提高.发生V(V)还原的细胞组分,胞外多糖及胞外蛋白含量增加,钒在细胞内外均有分布.傅里叶红外光谱(FTIR)分析表明菌体表面羟基、羰基、酰胺基参与生物吸附;扫描电镜(SEM)显示V(V)还原后菌体周围出现沉淀,能量散射x射线谱(EDS)结果表明沉淀物中有钒元素存在;X射线光电子能谱(XPS)分析表明菌株NC1-2将V(V)还原为V(IV);透射电镜(TEM)结果表明钒在细菌体内被沉淀.综上结果,菌株NC1-2能在细胞内和细胞外还原V(V)并形成不溶性V(IV)沉淀,NIR和NADH参与这一胞内生物转化过程.研究揭示了神户肠杆菌NC1-2还原V(V)的特性及内在机理,并简析其胞内电子传递过程.该菌株在钒污染修复中具有良好的应用前景.

Synthesis and Structural Characterization of [(C_2H_5)_4N][V^((V))O_2(OC_6H_3(OCH_3)CHNNCSNH_2)]·H_2O

The reaction of tetraethylammonium metavanadate, （Et4N）VO3, with isovanillin semithiocarbazone（VSTC）, HOC6H3（OCH3）CH=NNHCSNH2, in a mixed solvent of ethanol, water and DMSO yields the mononuclear dioxovanadate（V） complex, [（C2H5）4N][V（V）O2 （OC6H3- （OCH3）CHNNCSNH2）](H2O （C17H31N4O5SV, Mr = 454.5） and its single-crystal structure has been determined by X-ray diffraction. The crystal belongs to orthorhombic space group P212121 with unit cell parameters a = 12.940（3）, b= 15.414（3）, c = 10.703（2） ?, V = 2134.8（11） ?3, Z=4, Dcalc = 1.414 Kg/m3, ( = 0.597 mm-1, and F（000） = 960. The final agreement factors are R = 0.076 and Rw=0.096 for 1600 observed independent reflections with F ≥4.0(（F）. The structure revealed that the vanadium atom is bound to two terminal oxygen atoms and one tridentate donor ligand in a distorted square pyramidal arrangement. The sulphur-nitrogen-oxygen donor Schiff-base ligand in the thiol form rather than the thione form is coordinated to the vanadium via the mercapto sulphur, the (-nitrogen and the hydroxylate oxygen.

Electrochemical and structural evolution of structured V_(2)O_(5) microspheres during Li-ion intercalation

With the development of stable alkali metal anodes,V_(2)O_(5) is gaining traction as a cathode material due to its high theoretical capacity and the ability to intercalate Li,Na and K ions.Herein,we report a method for synthesizing structured orthorhombic V_(2)O_(5) microspheres and investigate Li intercalation/deintercalation into this material.For industry adoption,the electrochemical behavior of V_(2)O_(5) as well as structural and phase transformation attributing to Li intercalation reaction must be further investigated.Our synthesized V_(2)O_(5) microspheres consisted of small primary particles that were strongly joined together and exhibited good cycle stability and rate capability,triggered by reversible volume change and rapid Li ion diffusion.In addition,the reversibility of phase transformation(a,e,d,c and xLixV_(2)O_(5))and valence state evolution(5+,4+,and 3.5+)during intercalation/de-intercalation were studied via in-situ X-ray powder diffraction and X-ray absorption near edge structure analyses.