Release kinetics of vanadium from vanadium titano-magnetite: The effects of pH, dissolved oxygen, temperature and foreign ions.
Release kinetics of vanadium from vanadium titano-magnetite: The effects of pH, dissolved oxygen, temperature and foreign ions.
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DOI：
10.1016/j.jes.2017.07.001
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发表时间：
2017-07
影响因子：
6.9
通讯作者：
Xingyun Hu;Yuyan Yue;Xianjia Peng
中科院分区：
文献类型：
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作者：
Xingyun Hu;Yuyan Yue;Xianjia Peng
作为钒（V）环境地球化学行为研究的一部分，研究了在环境相关条件下，天然钒钛磁铁矿溶解过程中V的释放动力学。在酸性和碱性域中，V的释放速率被发现是成比例的分数功率的氢离子和溶解氧的活动。速率对溶解氧的依赖性也可以用Langmuir吸附模型来描述。经验速率方程由下式给出：r= k′ α H+ α Kα O2 1+ Kα O2式中，α= 0.0 99 ~ 0.2 6 5，k′= 3.2× 10− 6 ~ 1.7× 10− 5，K= 2.7 × 10 4 ~ 3.9× 10 4mol/L（pH4.1），α=− 0.494−（− 0.527），k′= 2.0× 104 -2.5× 10− 11，K= 4.1× 103 -6.5× 103mol/L。根据温度对钒释放速率的影响，测定了pH值为8.8时矿物的活化能为148-235 kJ/mol，表明钒钛磁铁矿的溶解是一个表面控制过程。Na+、Ca 2+、Mg 2+、K+、NO3-、Cl-、SO 42-和CO 32-的存在加速了V的释放。该研究提高了对某些矿区V污染风险和V在环境中归趋的认识。
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 O 2 1+ Kα O 2 where, α= 0.099–0.265, k′= 3.2× 10− 6–1.7× 10− 5, K= 2.7× 10 4–3.9× 10 4 mol/L in acid solution (pH 4.1), and α=− 0.494−(− 0.527), k′= 2.0× 10 4–2.5× 10− 11, and K= 4.1× 10 3–6.5× 10 3 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 pH 8.8 were determined to be 148–235 kJ/mol, suggesting that the dissolution of vanadium titano-magnetite is a surface-controlled process. The presence of Na+, Ca 2+, Mg 2+, K+, NO 3−, Cl−, SO 4 2− and CO 3 2− 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.