基于电化学法处理含铊废水的技术研究

发布时间：2019-01-18 19:14

【摘要】：铊(Tl)具有生物蓄积性,是一种剧毒重金属元素,在自然界中主要以Tl(I)形式存在。随着工业的不断发展,铊矿石的开采、冶炼导致环境铊污染现象日益严重。将迁移性强的Tl(I)氧化为Tl(III)并原位沉淀,是一种有前景的含铊废水处理方法。电化学技术性能高效、操作简便,近年来受到广泛关注,但当前尚未有利用电化学技术处理含铊废水的报道。本研究基于电化学技术,从供电电源、阳极材料、原位沉淀等角度,实现了含铊废水的高效处理。针对电化学技术电能消耗大的问题,引进新兴的微生物燃料电池作为供电电源,所采用的单室微生物燃料电池的输出功率达到518.5 mW/m2,最大电压达到700 mV(1000?)。以此为供电电源,以碳毡作为阳极,石墨板作为阴极并曝气,在初始Tl(I)浓度为5 mg/L,pH为2.0,施加电压为600 mV的条件下,经过4 h的电解,Tl(I)的氧化率达到了80.5%,再经过絮凝沉淀后,总铊的去除率为82.3%。并用X射线光电子能谱(XPS)证实了Tl(III)的生成。阳极材料对电化学氧化技术尤为关键。针对传统阳极材料氧化能力弱的问题,引进掺硼金刚石薄膜电极(BDD)作为阳极,石墨板作为阴极,在Tl(I)初始浓度为10 mg/L,pH为2.0,电流密度为5 mA/cm2的条件下,经过15 min的电解,Tl(I)的氧化率达到了99.2%,经过絮凝沉淀后,总铊得到完全去除,XPS证实了Tl(III)的生成,起作用的主要是电化学过程中产生的羟基自由基。针对电化学氧化后仍需经絮凝沉淀才能彻底净化含铊废水的问题,引进电絮凝工艺处理含铊废水,一步实现了Tl(I)的氧化与产物同步絮凝。比较了铁电极和铝电极的处理效果,结果表明铝电极更适用于含铊废水的电絮凝处理。当Tl(I)初始浓度为10 mg/L,pH为9.0,电流密度为5 mA/cm2时,经过60 min的电解,总铊的去除率达到了86.4%。对絮凝实验得到的沉淀进行XPS分析,结果表明沉淀物中的铊元素主要以Tl(III)为主。综上,本研究基于电化学技术实现了含铊废水的有效处理,利用微生物燃料电池作为供电装置降低了电化学技术的成本,利用BDD电极提高了电化学氧化技术的效率,利用电絮凝体系实现了一步法处理含铊废水,研究结果为含铊废水的高效处理,提供了新的方向和思路。
[Abstract]:Thallium (Tl), a highly toxic heavy metal element, is bioaccumulative and exists mainly in the form of Tl (I) in nature. With the development of industry and the exploitation of thallium ore, the environmental thallium pollution is becoming more and more serious. Oxidation of highly mobile Tl (I) to Tl (III) and in situ precipitation is a promising method for treatment of thallium containing wastewater. Electrochemical technology has attracted wide attention in recent years due to its high performance and simple operation. However, there are no reports on the treatment of thallium wastewater by electrochemical technology. Based on electrochemical technology, the high efficiency treatment of thallium wastewater was realized from the aspects of power supply, anode material and in situ precipitation. In order to solve the problem of high power consumption in electrochemical technology, a new microbial fuel cell is introduced as power supply. The output power of single-chamber microbial fuel cell is up to 518.5 mW/m2, and the maximum voltage is 700 mV (1000?). With carbon felt as anode, graphite plate as cathode and aeration, the initial Tl (I) concentration of 5 mg/L,pH is 2.0, and the applied voltage is 600 mV, after electrolysis for 4 h, the anode is used as power supply, the graphite plate is used as cathode and aeration, and the initial concentration of Tl (I) is 2.0, and the applied voltage is 600 mV. The oxidation rate of Tl (I) reached 80.5 and the removal rate of total thallium was 82.3 after flocculation and precipitation. The formation of Tl (III) was confirmed by X-ray photoelectron spectroscopy (XPS). Anode materials are particularly important for electrochemical oxidation. In order to solve the problem of weak oxidation ability of traditional anode materials, boron doped diamond film electrode (BDD) was introduced as anode, graphite plate as cathode, and the initial concentration of Tl (I) was 2.0 mg/L,pH at 10 mg/L,pH. At the current density of 5 mA/cm2, the oxidation rate of electrolytic, Tl (I) reached 99.2 after 15 min. After flocculation and precipitation, the total thallium was completely removed. The formation of Tl (III) was confirmed by XPS. The main action is the hydroxyl radical produced in the electrochemical process. Aiming at the problem that the wastewater containing thallium can be completely purified by flocculation and precipitation after electrochemical oxidation, this paper introduces an electroflocculation process to treat the wastewater containing thallium, and realizes the simultaneous flocculation of Tl (I) oxidation and product in one step. The results show that the aluminum electrode is more suitable for the treatment of thallium containing wastewater by electroflocculation. When the initial concentration of Tl (I) was 9. 0 mg/L,pH and the current density was 5 mA/cm2, the removal rate of total thallium reached 86.4% after 60 min electrolysis. The precipitation obtained from flocculation experiment was analyzed by XPS. The results showed that the main element of thallium in the precipitate was Tl (III). In summary, the effective treatment of thallium containing wastewater was realized based on electrochemical technology. The cost of electrochemical technology was reduced by using microbial fuel cell as power supply device, and the efficiency of electrochemical oxidation technology was improved by using BDD electrode. The one-step treatment of thallium wastewater was realized by using electric flocculation system. The results provided a new direction and thought for the efficient treatment of thallium containing wastewater.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703

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