电解条件对Cr^(3+)电化学氧化过程瞬时电流效率的影响研究  

Effects of Operating Conditions on Instantaneous Current Efficiency in the Electrochemical Oxidation Process of Cr^(3+) to Cr_2O_7^(2-)

作　　者：王雅琼[1] 周涛林[1] 许文林[1] 

机构地区：[1]扬州大学化学化工学院,江苏扬州225002

出　　处：《高校化学工程学报》2005年第6期824-828,共5页Journal of Chemical Engineering of Chinese Universities

基　　金：国家自然科学基金资助项目(20176047);江苏省教育厅自然科学基金资助项目(03KJB530164)

摘　　要：在隔膜式电解槽中,分别以PbO2和Ti/SnO2+Sb2O3/PbO2为阳极,以Cu为阴极,对硫酸介质中影响Cr3+电化学氧化生成Cr2O72-过程瞬时电流效率的因素进行了研究。实验结果表明,在硫酸介质中进行Cr3+电化学氧化时,操作电流密度、反应温度、硫酸浓度、阳极材料、超声等因素都会影响Cr3+电化学氧化生成Cr2O72?过程的瞬时电流效率。瞬时电流效率随操作电流密度和硫酸浓度的增大而下降,随反应温度的升高而增大;Ti/SnO2+Sb2O3/PbO2电极与PbO2电极比有较大的比表面积,瞬时电流效率高于PbO2电极;电解体系中引入超声,减小了电极表面的扩散层厚度,强化了Cr3+向电极表面的传质,超声场作用提高了瞬时电流效率。在25℃、硫酸浓度为1.5mol?L?1、Cr3+浓度为0.070mol.L-1、操作电流密度为0.02~0.15A.cm-2时,Ti/SnO2+Sb2O3/PbO2为阳极的瞬时电流效率比PbO2电极提高了4%~12%;在Cr3+浓度为0.040mol.L-1下操作,以Ti/SnO2+Sb2O3/PbO2为阳极,有超声场作用的瞬时电流效率比无超声作用时的瞬时电流效率提高了4%~11%。The factors affecting the instantaneous current efficiency in the electrochemical oxidation process of Cr^3＋ to Cr2O7^2- in H2SO4 solutions were studied in a divided electrolytic cell using PbO2 or Ti/SnO^2＋Sb2O3/PbO2 as anode and Cu as cathode. The results show that the instantaneous current efficiency for the Cr2O7^2- formation decreases with the increase of operating current density and the acid concentration, and it increases as the reaction temperature rises. The instantaneous current efficiency of using Ti/SnO^2＋Sb203/PbO2 electrode with a larger specific surface area is higher than that of using PbO2 electrode. The instantaneous current efficiency may be increased by the presence of ultrasound, since the action of ultrasound improves the mass-transport process. Under the conditions of 1.5 mol·L^-1 H2SO4 and 0.02 -0.15 A·cm^-2 at 25℃, the instantaneous current efficiency of the Ti/SnO2＋Sb2O3/PbO2 electrode is 4%～12% higher than that of the PbO2 electrode in 0.070 mol·L^-1 Cr^3＋ solution and when the ultrasound is used, the instantaneous current efficiency can be increased 4%～11% for the Ti/SnO2＋Sb2O3/PbO2 electrode in 0.040 mol·L^- Cr^3＋ solution.

关 键 词：电化学氧化 电流效率 CR3+ PBO2电极 

分 类 号：TQ150.1[化学工程—电化学工业] TQ151.41