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首页> 外文学位 >The speciation of molybdenum in sulfidic natural waters.
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The speciation of molybdenum in sulfidic natural waters.

机译：硫化自然水中的钼形态。

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摘要

In the presence of sulfide, MoO{dollar}sb4sp{lcub}2-{rcub}{dollar} undergoes a series of reactions in which O is replaced by S. In order to predict the rate of formation of thiomolybdates in natural waters, the kinetics of the reaction between MoO{dollar}sb4sp{lcub}2-{rcub}{dollar} and H{dollar}sb2{dollar}S were investigated in aqueous solutions buffered with {dollar}rm NHsb4sp+/NHsb3{dollar} (pH = 8.3-8.5) and {dollar}rm Hsb2S/HSsp-{dollar} (pH 7.0) at {dollar}25spcirc{dollar}C, I = 0.7-2 M. Equilibrium constants were determined from UV-vis spectral data obtained during kinetic runs for reactions with the general form:{dollar}{dollar}rm MoOsb{lcub}x{rcub}Ssb{lcub}4-x{rcub}sp{lcub}2-{rcub}+Hsb2S sbsp{lcub}gets{rcub}{lcub}to{rcub} MoOsb{lcub}x-1{rcub}Ssb{lcub}5-x{rcub}sp{lcub}2-{rcub}+Hsb2O (x=1{lcub}-{rcub}4){dollar}{dollar}All reactions were found to be catalyzed by NH{dollar}sb4sp+.{dollar} Acid catalysis was not observed in H{dollar}sb2{dollar}S buffered systems. The uncatalyzed rate of reaction was investigated in unbuffered solutions (pH = 8.0-9.0) in both deionized and filtered Chesapeake Bay water. No differences were observed between the rates of formation in the natural water sample and those in deionized water. Rate constants for the formation of the di-, tri-, and tetra-thiomolybdate anions were calculated according to rate law: -{dollar}dlbrack{lcub}rm MoOsb{lcub}x{rcub}Ssb{lcub}4-x{rcub}{rcub}sp{lcub}2-{rcub}rbrack/dt = {lcub}Sigma ksb{lcub}rm HA{rcub}lbrack{lcub}rm HA{rcub}rbrack{rcub}lbrack{lcub}rm MoOsb{lcub}x{rcub}Ssb{lcub}4-x{rcub}{rcub}sp{lcub}2-{rcub}rbracklbrack{lcub}rm Hsb2S{rcub}rbrack{dollar} - {dollar}{lcub}Sigma krmsb{lcub}HA{rcub}lbrack HArbrack/Ksb{lcub}eq{rcub}{rcub}lbrack MoOsb{lcub}x-1{rcub}Ssb{lcub}5-x{rcub}sp{lcub}2-{rcub}rbrack,{dollar} where {dollar}(Sigma ksb{lcub}rm HA{rcub}lbrack{lcub}rm HA{rcub}rbrack = ksb{lcub}rm Hsb2O{rcub}+ksb{lcub}rm H+{rcub}lbrack{lcub}rm H{rcub}sp+rbrack +krmsb{lcub}NH4+{rcub}lbrack NHsb4sp+rbrack +...).{dollar}; The concentration of Mo in seawater is {dollar}{lcub}sim{rcub}10sp{lcub}-7{rcub}{dollar} M, large enough that thiomolybdates are potentially important ligands for transition metals. The solubilities of FeS (pyrrhotite) and two Cu-S mineral assemblages, chalcocite-djurleite and anilite-covellite, were measured as a function of {dollar}rmSigma Ssp{lcub}2-{rcub}, Sigma Mo,{dollar} and pH. Copper and iron concentrations in solutions containing thiomolybdates are enhanced by many orders of magnitude relative to similar solutions containing no Mo. The following constants were obtained for I = 0.7 M:{dollar}{dollar}eqalign{lcub}&rm 2FeS (s){lcub}+{rcub}2MoOsb2Ssb2sp{lcub}2-{rcub}sbsp{lcub}spgets{rcub}{lcub}sbto{rcub}lbrack (MoOsb2Ssb2)sb2Fesb2Ssb2rbracksp{lcub}4-{rcub} K = (1.81pm0.65){lcub}times{rcub}10sp{lcub}-3{rcub}cr&rm 0.5Cusb2S+MoSsb4sp{lcub}2-{rcub}+ 0.5Hsp+sbsp{lcub}spgets{rcub}{lcub}sbto{rcub}CuMoSsb4sp- + 0.5HSsp- K = 295pm201cr&rm NHsb4CuMoSsb4 (s)sbsp{lcub}spgets{rcub}{lcub}sbto{rcub}NHsb4sp+ + CuMoSsb4sp- Ksb{lcub}sp{rcub} = (3.45pm0.69)times10sp{lcub}-7{rcub}cr{rcub}{dollar}{dollar}Rate constants for the formation of thiomolybdates and stability constants for their complexes with Fe and Cu are used to predict the speciation of Mo under a variety of naturally occurring conditions.
机译：在硫化物的存在下，MoO {dollar} sb4sp {lcub} 2- {rcub} {dollar}进行一系列反应，其中O被S取代。为了预测天然水中硫代钼酸盐的形成速率，在用rmrm NHsb4sp + / NHsb3 {dollar}（pH）缓冲的水溶液中研究了MoO {dolb} sb4sp {lcub} 2- {rcub} {dollar}和H {dollar} sb2 {dollar} S之间的反应动力学＝ 8.3-8.5）和{rm Hsb2S / HSsp- {dollar}（pH 7.0），在25spcirc {dollarC}，I = 0.7-2M。平衡常数是根据在一般形式的反应的动力学运行：{dollar} {dollar} rm MoOsb {lcub} x {rcub} Ssb {lcub} 4-x {rcub} sp {lcub} 2- {rcub} + Hsb2S sbsp {lcub} gets {rcub} {lcub}至{rcub} MoOsb {lcub} x-1 {rcub} Ssb {lcub} 5-x {rcub} sp {lcub} 2- {rcub} + Hsb2O（x = 1 {lcub}-{ rcub} 4）{dollar} {dollar}发现所有反应均被NH {dollar} sb4sp +催化。{dollar}在H {dollar} sb2 {dollar} S缓冲体系中未观察到酸催化。在去离子水和过滤的切萨皮克湾水中，在非缓冲溶液（pH = 8.0-9.0）中研究了未催化的反应速率。在天然水样品和去离子水中的形成速率之间未观察到差异。根据速率定律计算形成二，三和四硫代钼酸根阴离子的速率常数：-{dl} dlbrack {lcub} rm MoOsb {lcub} x {rcub} Ssb {lcub} 4-x { rcub} {rcub} sp {lcub} 2- {rcub} rbrack / dt = {lcub} Sigma ksb {lcub} rm HA {rcub} lbrack {lcub} rm HA {rcub} rbrack {rcub} lbrack {lcub} rm MoOsb {lcub} x {rcub} Ssb {lcub} 4-x {rcub} {rcub} sp {lcub} 2- {rcub} rbracklbrack {lcub} rm Hsb2S {rcub} rbrack {dollar}-{dollar} {lcub} Sigma krmsb {lcub} HA {rcub} lbrack HArbrack / Ksb {lcub} eq {rcub} {rcub} lbrack MoOsb {lcub} x-1 {rcub} Ssb {lcub} 5-x {rcub} sp {lcub} 2- { rcub} rbrack，{dollar}，其中{dollar}（西格玛ksb {lcub} rm HA {rcub} lbrack {lcub} rm HA {rcub} rbrack = ksb {lcub} rm Hsb2O {rcub} + ksb {lcub} rm H + { rcub} lbrack {lcub} rm H {rcub} sp + rbrack + krmsb {lcub} NH4 + {rcub} lbrack NHsb4sp + rbrack + ...）。{dollar};海水中Mo的浓度为{dol} {lcub} sim {rcub} 10sp {lcub} -7 {rcub} {dollar} M，其浓度足以使硫代钼酸盐成为过渡金属的潜在重要配体。测量了FeS（硫铁矿）和两种Cu-S矿物组合（辉绿辉绿辉石和苯胺体-珍珠岩）的溶解度，其函数为{dol} rmrm Ssp {lcub} 2- {rcub}，Sigma Mo，{dollar}和pH值相对于不含Mo的类似溶液，含硫代钼酸盐的溶液中的铜和铁浓度提高了多个数量级。对于I = 0.7 M，可获得以下常数：{dollar} {dollar} eqalign {lcub}＆rm 2FeS（s）{ lcub} + {rcub} 2MoOsb2Ssb2sp {lcub} 2- {rcub} sbsp {lcub} spgets {rcub} {lcub} sbto {rcub} lbrack（MoOsb2Ssb2）sb2Fesb2Ssb2rbracksp {lcub} 4- {rcub} 5 = 1 ）{lcub}次{rcub} 10sp {lcub} -3 {rcub} cr＆rm 0.5Cusb2S + MoSsb4sp {lcub} 2- {rcub} + 0.5Hsp + sbsp {lcub} spgets {rcub} {lcub} sbto {rcub} CuMoSsb4sp -+ 0.5HSsp- K = 295pm201cr＆rm NHsb4CuMoSsbb（s）sbsp {lcub} spgets {rcub} {lcub} sbto {rcub} NHsb4sp + + CuMoSsb4sp- Ksb {lcub} sp {rcub} =（3.45pm0.69）times10sp {lcub} -7 {rcub} cr {rcub} {dollar} {dollar}用于形成硫代钼酸盐的速率常数以及其与Fe和Cu的配合物的稳定性常数可用于预测在多种自然条件下Mo的形态。

著录项

  • 作者

    Erickson, Britt Elise.;

  • 作者单位

    University of Maryland, College Park.;

  • 授予单位 University of Maryland, College Park.;
  • 学科 Geochemistry.; Biology Limnology.; Chemistry Analytical.
  • 学位 Ph.D.
  • 年度 1998
  • 页码 259 p.
  • 总页数 259
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;化学;
  • 关键词

  • 入库时间 2022-08-17 11:48:35

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