As part of a broader study of the environmental geochemistry behavior of vanadium（V）, the release kinetics of V from the dissolution of natural vanadium titano-magnetite under environmentally relevant conditions was...As part of a broader study of the environmental geochemistry behavior of vanadium（V）, the release kinetics of V from the dissolution of natural vanadium titano-magnetite under environmentally relevant conditions was investigated. In both the acidic and basic domains, the V release rate was found to be proportional to fractional powers of hydrogen ion and dissolved oxygen activities. The dependence of the rate on dissolved oxygen can also be described in terms of the Langmuir adsorption model. The empirical rate equation is given by： r= k′α（H＋）α（Kα（O2））/（1＋Kα（O2）） where, α = 0.099–0.265, k′ = 3.2 × 10-6–1.7 × 10-5, K =2.7 × 104–3.9 × 104 mol/L in acid solution（pH 4.1）, and α =-0.494-（-0.527）, k′ = 2.0 × 104–2.5 × 10-11, and K = 4.1 × 103–6.5 × 103 mol/L in basic solution（pH 8.8） at 20°C. Based on the effect of temperature on the release rate of V, the activation energies of minerals at p H 8.8 were determined to be 148–235 k J/mol, suggesting that the dissolution of vanadium titano-magnetite is a surface-controlled process. The presence of Na＋, Ca2＋, Mg2＋, K＋, NO3-, Cl-, SO42-and CO32-was found to accelerate the V release rates. This study improves the understanding of both the V pollution risk in some mine areas and the fate of V in the environment.展开更多
Batch experiments were performed to derive the rate laws for the proton-promoted dissolution of the main vanadium（Ⅲ, Ⅳ and Ⅴ） oxides at pH 3.1–10.0. The release rates of vanadium are closely related to the aqueo...Batch experiments were performed to derive the rate laws for the proton-promoted dissolution of the main vanadium（Ⅲ, Ⅳ and Ⅴ） oxides at pH 3.1–10.0. The release rates of vanadium are closely related to the aqueous pH, and several obvious differences were observed in the release behavior of vanadium from the dissolution of V2O5 and vanadium（Ⅲ, Ⅳ） oxides. In the first 2 hr, the release rates of vanadium from V2O3 were r = 1.14·（[H＋]）-0.269 at pH 3.0–6.0 and r = 0.016·（[H＋]）-（-0.048） at pH 6.0–10.0; the release rates from VO2 were r = 0.362·（[H＋]）-0.129 at pH 3.0–6.0 and r = 0.017·（[H＋]）-（-0.097） at pH 6.0–10.0; and the release rates from V2O5 were r = 0.131·（[H＋]）--（0.104） at pH 3.1–10.0. The release rates of vanadium from the three oxides increased with increasing temperature, and the effect of temperature was different at pH 3.8, pH 6.0 and pH 7.7. The activation energies of vanadium（Ⅲ, Ⅳ and Ⅴ） oxides（33.4–87.5 kJ/mol） were determined at pH 3.8, pH 6.0 and pH 7.7, showing that the release of vanadium from dissolution of vanadium oxides follows a surface-controlled reaction mechanism. The release rates of vanadium increased with increasing vanadium oxides dose,albeit not proportionally. This study, as part of a broader study of the release behavior of vanadium, can help to elucidate the pollution problem of vanadium and to clarify the fate of vanadium in the environment.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21607166,41641034 and 41473113)the National Water Pollution Control and Treatment Science and Technology Major Project(No.2015ZX07205-003)
文摘As part of a broader study of the environmental geochemistry behavior of vanadium（V）, the release kinetics of V from the dissolution of natural vanadium titano-magnetite under environmentally relevant conditions was investigated. In both the acidic and basic domains, the V release rate was found to be proportional to fractional powers of hydrogen ion and dissolved oxygen activities. The dependence of the rate on dissolved oxygen can also be described in terms of the Langmuir adsorption model. The empirical rate equation is given by： r= k′α（H＋）α（Kα（O2））/（1＋Kα（O2）） where, α = 0.099–0.265, k′ = 3.2 × 10-6–1.7 × 10-5, K =2.7 × 104–3.9 × 104 mol/L in acid solution（pH 4.1）, and α =-0.494-（-0.527）, k′ = 2.0 × 104–2.5 × 10-11, and K = 4.1 × 103–6.5 × 103 mol/L in basic solution（pH 8.8） at 20°C. Based on the effect of temperature on the release rate of V, the activation energies of minerals at p H 8.8 were determined to be 148–235 k J/mol, suggesting that the dissolution of vanadium titano-magnetite is a surface-controlled process. The presence of Na＋, Ca2＋, Mg2＋, K＋, NO3-, Cl-, SO42-and CO32-was found to accelerate the V release rates. This study improves the understanding of both the V pollution risk in some mine areas and the fate of V in the environment.
基金supported by the National Natural Science Foundation of China(Nos.21607166,41641034 and 41473113)the National Water Pollution Control and Treatment Science and Technology Major Project(No.2015ZX07205-003)
文摘Batch experiments were performed to derive the rate laws for the proton-promoted dissolution of the main vanadium（Ⅲ, Ⅳ and Ⅴ） oxides at pH 3.1–10.0. The release rates of vanadium are closely related to the aqueous pH, and several obvious differences were observed in the release behavior of vanadium from the dissolution of V2O5 and vanadium（Ⅲ, Ⅳ） oxides. In the first 2 hr, the release rates of vanadium from V2O3 were r = 1.14·（[H＋]）-0.269 at pH 3.0–6.0 and r = 0.016·（[H＋]）-（-0.048） at pH 6.0–10.0; the release rates from VO2 were r = 0.362·（[H＋]）-0.129 at pH 3.0–6.0 and r = 0.017·（[H＋]）-（-0.097） at pH 6.0–10.0; and the release rates from V2O5 were r = 0.131·（[H＋]）--（0.104） at pH 3.1–10.0. The release rates of vanadium from the three oxides increased with increasing temperature, and the effect of temperature was different at pH 3.8, pH 6.0 and pH 7.7. The activation energies of vanadium（Ⅲ, Ⅳ and Ⅴ） oxides（33.4–87.5 kJ/mol） were determined at pH 3.8, pH 6.0 and pH 7.7, showing that the release of vanadium from dissolution of vanadium oxides follows a surface-controlled reaction mechanism. The release rates of vanadium increased with increasing vanadium oxides dose,albeit not proportionally. This study, as part of a broader study of the release behavior of vanadium, can help to elucidate the pollution problem of vanadium and to clarify the fate of vanadium in the environment.
