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镓电解电极材料及溶液中阴离子的影响
Alternative TitleThe Effect of Electrode Materials and Anions in the Electrolyte on the Gallium Electro-deposition
李科科
Subtype硕士
Thesis Advisor张亦飞
2013-05-01
Degree Grantor中国科学院研究生院
Degree Discipline化学工艺
Keyword镓   电沉积   电流效率   阴极电位   阴离子
Abstract镓被誉为高新技术的支撑材料。近年来,随着其在电子工业的广泛应用,世界对镓的需求不断增长。但镓是一种稀散金属,没有独立的矿床,目前大约90%的镓是在氧化铝生产中回收的。利用树脂吸附法从氧化铝生产的循环碱液中回收镓被越来越多的企业所采用。树脂吸附得到的镓经过碱液淋洗造液、净化后,通过电沉积的方法从碱性电解液中提取镓,可得到纯度高于99.9%的金属镓。但镓电解的电流效率很低。本论文主要从阴极电位和电流效率两方面对从碱性电解液中电沉积提取镓进行了系统的研究,以考察电沉积的各项条件,尤其是电极材料和溶液中阴离子对电流效率的影响。首先,实验对电极材料和电解液的碱浓度进行了研究。研究发现,SUS304不适合作电解阳极。当采用SUS304作阳极时,其会被腐蚀,电解液被严重污染,同时阴极电位相对较高,最终在阴极得到的是铁,电流效率几乎为0。当采用SUS316作为阴极和阳极时是比较合适的;实验中发现,随着NaOH浓度的增大,阴极电位逐步升高。过高的碱浓度不仅会加速阴极沉积镓的返溶,同时会产生阳极钝化现象,造成电流效率的大幅降低。当电解液中NaOH浓度为4 mol/L 时,电流效率最高,为6.30%。其次,实验考察了电解条件,包括搅拌速度、电极间距、温度及电流密度,对镓电沉积的影响。搅拌速度对阴极电位和电流效率几乎没有影响,当电极间距为2 cm、电解温度为40 ℃、电流密度为0.10 A/cm2时对镓的电沉积最有利。再次,实验对碱性电解液中的阴离子,包括SO42-、SiO32-、CO32-、AlO2-、F-和Cl-对镓电沉积的影响进行了研究。当电解液中加入不同浓度的SO42-、CO32-、F-和Cl-时,阴极电位会有所降低,但最大不超过0.1V;对于SiO32-和AlO2-,其在溶液中浓度的增大会使阴极电位升高,并且当其浓度过大时,阴极电位剧增,同时在阴极得到的Ga表面呈现如同灼烧般的灰黑色,并且比较粗糙。当电解液中含有SO42-、SiO32-、CO32-、AlO2-、F-和Cl-时,基本上都会造成电流效率的下降,但当溶液中含有0.2 mol/L的Cl-时,电流效率会有略微的提升。与其它离子相比,Cl-对电流效率的影响较小。
Other AbstractGallium is honoured as the backing material of high and new technology. The demands for gallium has increased much because of its more and more extensive application in electronics industry. As a dissipated metal, gallium has no its own independent deposits and is mainly, about 90%, produced as a by-product from the production of alumina. Pre-concentration by adsorbing gallium from cyclic alkaline solutions using resin is adopted by more and more enterprises. The gallium got by resin adsorption is eluted by alkaline solution and then the metal gallium with purity over 99.9% could be got by electro-deposition from the purified alkaline solution.However, the current efficiency of gallium electro-deposition is very low. The present work focused on the effect of electrolysis terms and conditions on the current efficiency of gallium electro-deposition (mainly on the cathode potential and current efficiency) by systematic study.Firstly, the electrode material and the alkalinity of electrolyte were studied. It was found that SUS304 was unsuitable to be used as the anode for gallium electro-deposition because of its serious corrosion, the severe being contaminated of electrolyte, the relatively-high cathode potential, the final product with none-gallium and the current efficiency with nearly 0%. SUS316 was suitable to be used as anode and cathode. The cathode potential increased with the NaOH concentration in electrolyte. The highest current efficiency with 6.30% was got when the NaOH concentration was 4 mol/L. High NaOH concentration would cause anodic passivation and sharp decrease of current efficiency.Secondly, the effect of stirring speed, electrode distance, electrolysis temperature and current density on gallium electro-deposition was studied. The stirring speed had no influence on the cathode potential and current efficiency almost. The best conditions for gallium electro-deposition were the electrode distance with 2 cm, the electrolysis temperature with 40 ℃,and the current density with 0.10 A/cm2. Thirdly, the effect of SO42-, SiO32-, CO32-, AlO2-, F- and Cl- in the electrolyte on gallium electro-deposition was studied. The cathode potential would decrease, less than 0.1V, with the addition of SO42-, CO32-, F- and Cl- with various concentrations. On the contrary, the addition of SiO32- and AlO2- would make the cathode potential increase. Especially, high SiO32- and AlO2- concentration not only made the cathode potential increase sharply but also harmed the gallium deposited on the cathode severely, tiny black and coarse. The current efficiency for gallium electro-deposition decreased with increasing the concentrations of almost all the anions, SO42-, SiO32-, CO32-, AlO2-, F- and Cl- in the electrolyte, except for that the current efficiency was slightly improved in the electrolyte with 0.2M Cl-. Compared with other anions, the effect of Cl- on the current efficiency was most slight.
Pages67
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/8266
Collection研究所(批量导入)
Recommended Citation
GB/T 7714
李科科. 镓电解电极材料及溶液中阴离子的影响[D]. 中国科学院研究生院,2013.
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