典型含钒矿物中钒的溶解释放动力学和机理

发布时间：2018-07-28 16:38

【摘要】：钒(V)是一种潜在有毒的元素,有金属“维生素”之称,普遍应用于机械、汽车、造船、电子技术、铁路、航空等行业,全钒液流电池中电解质溶液,制硫酸和硫化橡胶的催化剂,陶瓷着色剂和显影剂等。因为人们的自然活动以及钒化合物的普遍使用,环境中钒的污染愈来愈严重,中国《重金属污染综合防治规划》,已经把钒作为14(5+9)种被重点防控的重金属之一。由于钒是中国的优势资源之一,全球过半数的钒都是由中国提供的,在矿区钒污染事件的发生越来越多。造成钒污染除了人为活动排放的废水、废气和废渣,钒矿石的敞天堆放、废石经过雨水或者是矿区中排水冲洗是钒溶解释放的主要途径。已有的研究主要是钒的环境化学、形态分布、生物有效性以及钒矿中钒的提取和测定,有关于钒矿物本身的溶解、风化及其钒的地球环境化学循环的研究很少,钒矿物的溶解作为钒地球化学循环的首步,目前,钒的溶解释放动力学和机理仍然十分不清楚。本论文主要是针对我国钒资源丰富、消耗量大和钒的潜在危害性,在已经研究的基础上,初步地开展了典型的含钒矿物(石煤钒矿,钒钛磁铁矿)和钒的氧化物(V2O5,VO2,V2O3)中钒的溶解释放动力学特征和和主要影响因素的研究,揭示了含钒矿物溶解释放机理,探讨化学过程对钒释放的影响。不但可以利于我们更深入地了解钒的地球化学循环,还能为水体中钒污染的预防和控制提供强有力地理论支持。实验中研究结果如下:1、钒氧化物(III,IV和V)的溶解释放在pH值3.1-10.0的条件下,做批量实验研讨钒的主要氧化物(III,IV和V)的溶解速率定。实验中发现,钒的溶解释放与溶液中的pH值有密切的关系,并且清晰地观察到溶液中V2O5和钒氧化物(III,IV)的溶解释放行为。在第一个2 h,V2O3的溶解速率是r=1.14·([H+])0.269(pH 3.0-6.0)和r=0.016·([H+])-0.048(pH 6.0-10.0);VO2的溶解速率是r=0.362·([H+])0.129(pH 3.0-6.0)和r=0.017·([H+])-0.097(pH 6.0-10.0);V2O5在溶液pH3.1-10.0的溶解速率是r=0.131·([H+])-0.104。钒的三种氧化物的等电点pH PZC大约是2或者更小。钒的氧化物的释放率随着温度的增加而增加,在不同的pH(3.8,6.0和7.7)下,温度对其溶解速率的影响各不相同,实验测得钒的三种氧化物的激活能是33.4-87.5kJ·mol-1,表明钒氧化物的释放是解散表面控制反应机制。钒的释放速率随着钒氧化物的剂量增加而增加,虽然不成比例。这作为更大量的钒的释放行为研究,有助于阐明钒的污染问题和环境中钒的迁移转化。2、有机质作用下,石煤中钒的溶解释放动力学在自然环境状态下,低分子溶解性有机质(LMWDOMs)对钒矿物中钒的溶解释放的影响是目前广泛研究的一个热点。实验中做了八种典型的含有羧基、羟基和氨基的天然低分子溶解性有机质:柠檬酸、草酸、EDTA、水杨酸、邻苯二酚、甘氨酸、半胱氨酸和葡萄糖。在全恒温培养箱中保持室温(25℃)下,实验中每种LMWDOMs分别在pH4.0、6.0和8.0的缓冲溶液中进行。结果表明,在酸性和碱性溶液中,含羧基的低分子溶解性有机质对钒的释放作用比较大。在pH 4.0时,柠檬酸、草酸和EDTA溶液中,钒最开始的释放速率大约是空白对照实验的25-39倍;溶解平衡时的释放速率分别是对照实验的164、95和49倍;邻苯二酚存在的情况下,pH 8.0溶液中的释放率约是pH 4.0的20倍;氨基酸和醇类对钒的释放影响比较小。此外,利用衰减全反射红外光谱(ATR-FTIR)和电子顺磁共振技术(EPR)对于低分子溶解性有机质对金属离子钒释放机制的特征进行了分析。本章实验的研究有助于理解一些矿山地区钒的污染风险和环境中钒的迁移转化过程。3、钒钛磁铁矿的溶解释放动力学实验的设计是在混合蠕动泵反应器中,V的释放行为在很大程度上受pH值、温度、溶解氧和离子的影响。V的释放速率方程式是基于酸性和碱性条件下来探讨钒钛磁铁矿反应速率定律。实验中得出,钒的反应速率与部分氢离子和溶解氧活度成正比,溶解氧对钒钛磁铁矿表面中钒的溶解可以用朗格缪尔定律来解释,这种现象也对解释钒的溶解饱和度有很大的优势;同样地,碱性条件下研究钒溶解的饱和度需要更高的氧分压。反应温度是影响V释放的另一个重要因素,酸性溶液和碱性溶液中,矿物表面的激活能量对矿物的溶解机制有一定的控制作用;实验还发现铁离子促进了钒的释放。此外,矿物中钒在溶液中的溶解浓度远远小于V2O5理论溶解度,这是归因于钒矿物样本共存组分对钒的吸附和沉淀作用。
[Abstract]:Vanadium (V) is a potentially toxic element, known as a metal "vitamin". It is widely used in machinery, automobile, shipbuilding, electronic technology, railway, aviation and other industries, electrolyte solutions of all vanadium redox cells, sulfuric acid and vulcanized rubber catalysts, ceramic coloring agents and developer, etc. because of the natural activities of people and the common vanadium compounds. For use, the pollution of vanadium is becoming more and more serious in the environment. China has taken vanadium as one of the 14 (5+9) heavy metals to prevent and control heavy metals. As vanadium is one of the dominant resources in China, more than half of the vanadium in the world is provided by China, and more and more vanadium pollution events occur in the ore area. Waste water, waste gas and waste residue, the open stack of vanadium ore, the waste stone passing through the rainwater or the drainage in the mining area is the main way to dissolve the vanadium. The existing research is mainly on the environmental chemistry of vanadium, the distribution of the form, the bioavailability and the extraction and determination of vanadium in the vanadium ore, and the dissolution of the vanadium mineral itself. There are few studies on the chemical cycle of the earth environment of vanadium and its vanadium. The dissolution of vanadium minerals is the first step in the geochemical cycle of vanadium. At present, the kinetics and mechanism of the dissolution and release of vanadium are still unclear. This paper is mainly aimed at the abundant vanadium resources in China, the great consumption of vanadium and the potential harmfulness of vanadium. The dissolution and release kinetics of vanadium containing typical vanadium containing minerals (vanadium minerals, vanadium and titanium magnetite) and vanadium (V2O5, VO2, V2O3) are studied. The dissolution and release mechanism of vanadium containing minerals and the effect of chemical process on the release of vanadium are revealed, which can not only help us to understand vanadium more deeply. The study cycle can provide strong theoretical support for the prevention and control of vanadium pollution in the water. The experimental results are as follows: 1, the dissolution of vanadium oxide (III, IV and V) is released under the condition of pH 3.1-10.0, and the dissolution rate of the main oxides (III, IV and V) of vanadium is studied in batch experiments. The dissolution and dissolution of vanadium and dissolution of vanadium are found in the experiment. The dissolution rate of V2O5 and vanadium oxide (III, IV) in the solution was clearly observed. In the first 2 h, the dissolution rate of V2O3 was r=1.14. ([H+]) 0.269 (pH 3.0-6.0) and r=0.016 ([H+]). (pH 6.0-10.0); the dissolution rate of V2O5 in solution pH3.1-10.0 is about 2 or smaller at the isoelectric point pH PZC of three oxides of r=0.131 ([H+]) -0.104. vanadium. The release rate of vanadium oxide increases with the increase of temperature. At different pH (3.8,6.0 and 7.7), the effect of temperature on the dissolution rate of vanadium is not the same, and the experimental results show three of the vanadium. The activation energy of the oxide is 33.4-87.5kJ. Mol-1, which indicates that the release of vanadium oxide is a disbanded surface controlled reaction mechanism. The release rate of vanadium increases with the increase of the dose of vanadium oxide, although it is disproportionate. This is a study of the release behavior of a larger number of vanadium, which helps to clarify the problem of vanadium pollution and the transfer of vanadium in the environment to.2. Under the action of organic matter, the dissolution and release kinetics of vanadium in stone coal in natural environment, the effect of low molecular dissolved organic matter (LMWDOMs) on the dissolution and release of vanadium in vanadium minerals is a hot spot at present. In the experiment, eight typical natural low molecular dissolved organic matter containing carboxyl groups, hydroxyl groups and amino groups: citric acid Oxalic acid, EDTA, salicylic acid, catechol, glycine, cysteine and glucose were kept at room temperature at room temperature (25 degrees C) in a full thermostat incubator. Each LMWDOMs was carried out in the buffer solution of pH4.0,6.0 and 8 respectively. The results showed that the release of low molecular dissolved organic matter with carboxyl group was larger in the acid and alkaline solution. At pH 4, the initial release rate of vanadium in citric acid, oxalic acid and EDTA solution is about 25-39 times as much as that in the blank control experiment; the release rate of the dissolution balance is 164,95 and 49 times of the control experiment; the release rate of pH 8 in the presence of catechol is about 20 times as much as pH 4, and the release of amino acids and alcohols on vanadium In addition, the characteristics of the mechanism of the release of vanadium from metal ions by low molecular dissolved organic matter were analyzed by the attenuated total reflection infrared spectroscopy (ATR-FTIR) and electronic paramagnetic resonance (EPR). This chapter is helpful to understand the pollution risk of vanadium in some mining areas and the transition and transformation process of vanadium in the environment,.3, vanadium. The dissolution and release kinetics experiment of titanium magnetite was designed in a mixed peristaltic pump reactor. The release behavior of V was greatly influenced by the pH value, temperature, dissolved oxygen and ions. The equation of the release rate of.V was based on the acid and alkaline conditions, and the reaction rate of vanadium and titanium magnetite was determined in the experiment. The dissolution of vanadium in the vanadium and titanium magnetite surface can be explained by Langmuir's law, which is also proportional to some hydrogen ions and dissolved oxygen activity. This phenomenon also has a great advantage to explain the dissolved saturation of vanadium. Similarly, the study of the saturation of vanadium in the alkaline condition requires a higher oxygen partial pressure. The reaction temperature is the influence of V release. In the acid solution and the alkaline solution, the activation energy of the mineral surface has a certain control effect on the dissolution mechanism of the mineral. The experiment also found that iron ions promote the release of vanadium. In addition, the dissolved concentration of vanadium in the solution is far less than the V2O5 theory solubility, which is attributed to the coexistence of vanadium mineral samples. The adsorption and precipitation of vanadium.
【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X142

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