电场法水中除砷机理及不同材料除砷效率研究

【作者】 王娟；

【导师】 张曙；

【作者基本信息】 云南大学 ， 材料加工工程， 2010， 硕士

【摘要】 早在公元317年中国人就首先发现了砷。砷广泛存在于自然界中,目前已知在三百多种矿物中都含有砷。砷主要通过含砷矿物的风化、人类的生产生活活动等途径而进入水体。据文献报道,每年全球通过上述途径进入水圈的砷就有11万吨。元素砷对人和生物无毒,但砷化物对人体非常有害,砷化物能使人致癌、致畸和致突变,长期饮用高砷水会对皮肤、肝、肾、神经系统和生殖系统等造成伤害。砷化合物的毒性及其大小与其形态有关,无机砷化物的毒性大于有机砷。砷污染治理已是当今全球环境保护刻不容缓的问题。阳宗海砷污染及其治理就是向人类提出的一个严重挑战。目前砷污染治理主要是针对工业废水,处理的主要方法有:沉淀法、离子交换法、氧化法、吸附法、膜分离法、生物法等。电场法水中除砷以受砷污染的农灌、养殖、饮用水体为研究对象,以全新的视角、方法对砷污染治理展开研究。砷在水中主要以三价砷As(Ⅲ)和五价砷As(Ⅴ)的形态存在。As(Ⅲ)可经氧化形成As(Ⅴ),As(Ⅴ)在弱酸、中性和碱性水体呈电性,占80%以上,且是砷的主要存在形态。本论文在云南阳宗海砷污染治理的大背景下,针对大型受砷污染的弱碱性(pH =8.5-9.0)的水体(如湖泊、水库等)除砷进行机理和实验探索。研究表明,电场法水中除砷产生三个效应两个过程:水中砷酸根在正极富集效应,极板金属原子的电离效应,水电解、砷酸根氧化效应;通过金属离子与砷酸根反应形成难溶性砷酸盐沉淀过程,金属氢氧化物与砷酸根、亚砷酸根的络合反应( As ?O?)的共沉淀吸附过程,达到低碳、高效、无污染除砷。通过对不同材料电极除砷的实验研究,分析总结不同材料电极(铜、铝、铁)除砷的规律及其效率,并在此基础上提出在实际应用中采用间歇电场,可充分实现低碳、高效的观点,设计间歇电场法水中除砷装置,在实际水体中进行试验,结果好于预期。选择适当的作用参数,水中砷含量可降3个数量级。本论文对电场法水中除砷进行总结归纳,提出了研究的特色和创新之处。更多还原

【Abstract】 At about AD 317, the arsenic was found by Chinese people. Arsenic widely exists in nature, more than 300 kinds of minerals are known to contain arsenic. Arsenic mainly filters into water by the weathering of arsenic minerals, or by the production of human activities. It was reported that there are 110,000 tons of arsenic enter into the cycle water each year.Element arsenic is Non-toxic, but the arsenides can harm people and cause carcinogenic、teratogenic and mutagenic. Long-term consumption water with high concentration of arsenic will damage skin, liver, kidney, nervous system and reproductive system. The toxicity of arsenic compounds is relevant to its shape, and the toxicity of inorganic arsenic is greater than organic arsenic. Arsenic pollution becomes imperatively a global environmental problem at present. The control and decrease of arsenic pollution of Yangzonghai is a serious challenge.Currently, the main target is the control of arsenic pollution from industrial wastewater, and the main control methods include such techniques as precipitation, ion exchange, oxidation, adsorption, membrane separation, and biological methods, etc. Using the electric field method on the removal of arsenic in water for agricultural irrigation、aquaculture、drinking water, can be a new perspective and method to study the arsenic pollution. The arsenic in the water mainly exists as trivalent arsenic As (Ⅲ) and pentavalent arsenic As (Ⅴ). As (Ⅲ) can be transformed from the oxidation of As (Ⅴ), As (Ⅴ) in weak acid, neutral and alkaline water are electric, more than 80%, and is the primary form of arsenic.The background of this thesis is arsenic contamination in Yangzonghai, Yunnan province, for large-scale arsenic contamination by weak alkaline (pH= 8.5-9.0) of water bodies (such as lakes, reservoirs, etc.) in addition to the mechanism and experimental exploration of arsenic. The results show that removing the arsenic in water by the electric field method include three effects and the two processes: Plate metal atom ionization effect, arsenate accumulation in the anode, water electrolysis, oxidation of arsenate. Reaction of metal ions and arsenate induces the formation of insoluble arsenate, metal hydroxide and arsenate, sub-arsenite complexation reaction ( As ? O?) form of coprecipitation adsorption. These productions of reaction favor the achievement of low-carbon, efficient, pollution-free removal of arsenic in water. Electrodes with different metal materials (copper, aluminum, iron) have been used in the arsenic removal experiment. Then, we analyze and summarize the law and efficiency of removal of arsenic. On this basis, the intermittent electric field method, which can be fully realized the view of low-carbon, high efficiency, is proposed to be used in the practical application. In this thesis, the arsenic removal device has been designed, and the intermittent electric field method has been conducted, and the results of removing arsenic are better than our prevenient expected. There three orders of magnitude of arsenic concentration can be decreased by selecting the appropriate role of parameters. The remove the arsenic in water by the electric field method are well summarization in the thesis, and the features and innovations of this method are also proposed.更多还原