二氧化铅的水溶液体系还原研究

分别采用硫酸亚铁和亚硫酸钠对PbO_2进行还原研究,考察了还原剂浓度(过量系数)、反应时间、反应温度等工艺参数对PbO_2还原率的影响。利用X射线衍射(XRD)、扫描电子显微镜(SEM)等分析还原产物的物相和形貌。结果表明:硫酸亚铁为还原剂时,PbO_2的还原率随着还原剂浓度的降低、反应温度的升高而增加,反应时间对PbO_2还原率影响较小。硫酸亚铁还原最佳条件为:硫酸亚铁过量系数为1~1.1,反应时间为60 min,反应温度为90℃,n(H_2SO_4)∶n(PbO_2)为3∶1,二氧化铅还原率最高仅为52.4%;亚硫酸钠作为还原剂时,PbO_2的还原率随着亚硫酸钠过量系数增加和反应温度的提高而增大,反应时间对PbO_2还原率影响较小,当亚硫酸钠过量系数为6.0、反应温度为90℃、反应时间为60 min时,PbO_2还原率可达100%,完全还原后,粉体由近球形演变为短棒状。

REDUCTION OF LEAD DIOXIDE IN AQUEOUS SOLUTION

Lead dioxide (PbO2) powder were reduced and transformed in aqueous solution by ferrous sulfate(FeSO4) and sodium sulfite(Na2SO3),respectively.The influences of process parameters,such as reducing agent concentration,reaction time and reaction temperature,upon the reduction rate of PbO2 were studied in detail.The phase and morphology of reduction products were examined by X-ray diffraction (XRD) and scan electron microscope (SEM),respectively.The experimental results showed that,when FeSO4 was used as reducing agent,PbO2 reduction rate was increased with lower reducing agent concentration and higher temperature,while the time has little effect on the reduction rate.The optimum conditions for the FeSO4 reduction were as follows:The excess coefficient of FeSO4 was 1 ～ 1.1,the reaction time was 60 min,the reaction temperature was 90 ℃,the molar ratio of H2SO4 to PbO2 was 3∶ 1,and the maximum reduction rate of PbO2 was only 52.4％.When Na2SO3 was used as reducing agent,PbO2 reduction rate was increased with higher excess coefficient at elevated temperature,while the time has little effect on the reduction rate.The reduction rate of PbO2 could reach 100％ with Na2SO3 excess coefficient of 6.0 at 90 ℃ for 60 min.After reduced by Na2SO3,the morphology of the powder transformed from nearly spherical to rod like particles.