Selection of Anodic Material Used in Electrolytic Process for Producing Hypophosphorous Acid Selection of Anodic Material Used in Electrolytic Process for Producing Hypophosphorous Acid

Selection of Anodic Material Used in Electrolytic Process for Producing Hypophosphorous Acid

  • 期刊名字:中国化学快报
  • 文件大小:832kb
  • 论文作者:Fu Sheng WANG,Bing Kui SONG,Xi
  • 作者单位:College of Environmental Science &Engineering
  • 更新时间:2020-11-22
  • 下载次数:
论文简介

Chinese Chemical Letters Vol. 15, No.12, pp 1487- 1490, 20041487http://www.imm.ac.cn/journal/ccl.htmlSelection of Anodic Material Used in Electrolytic Process forProducing Hypophosphorous AcidFu Sheng W ANG*, Bing Kui SONG, Xiao Li HAN, Bao Gui ZHANGCollege of Environmental Science & Engineering, Nankai University, Tianjin 300071Abstract: Black lead, Ti-Ru and Ti- PbO2 were used as anode and stainless steel was used as cathode.The electrolytic process of producing hypophosphorous acid with four-compartment electrodialyticcell was studied. The comparison of some factors, such as anodic voltage, product concentrationand current efficiency, of black lead, Ti-Ru, and Ti-PbO2 electrodes was conducted. As a result, theTi-PbO2 elctrode is the optimal anode material used, it can be in electrolytic process for producinghypophosphorous acid.Keywords: Hypophosphorous acid, electrolysis, anodic material.There are some references in abroad and in China. Sodium hypophosphite was used asraw material to produce hypophosphorous acid by electrolysis 15. According to thepatents and literatures reported, Ti-Ru electrode and black lead electrode have been usedas anode in electrolytic process for producing hypophosphorous acid. Ti-Ru electrodecannot be applied widely in industry due to high cost and scarce resource of ruthenium inChina. Although black lead anode is much cheaper, the application of black lead anode islimited because of following shortcomings: short lifetime, severely environmentalpollution, and affecting the permeated capability of membrane. Therefore, it is veryimportant to search new anodic material used for electrolytic process of producinghypophosphorous acid. Based upon correlative information', Ti- PbO2 electrode, cheaperthan Ti-Ru electrode, was selected as the anode. In this paper, the performances of blacklead electrode, Ti PbO2 electrode and Ti-Ru electrode were compared and discussed.The experimental apparatus is a four-compartment electrodialytic cell shown inFigure 1.When a direct current flowed through the electrodialytic cell, the water wasdecomposed, and generated hydrogen ions in anodic compartment. The hydrogen ionsmembrane (C) nder the action of electric field force. The anionic exchange membrane (A)isted cation diffusion and retained the hydrogen ions in product compartment. Thematerial compartment started with a concentrated solution of sodium hypophosphite.The hypophosphite ions transferred through anionic exchange membrane from materialcompartment to product compartment under the action of electric field force. The"E-mail: fswang3418@ sohu.com中国煤化工MHCNMH G.1488Fu Sheng WANG et al.cationic exchange membrane resisted anion diffusion and retained the hypophosphite ionsin product compartment. As a result, the hypophosphite ions were combined withhydrogen ions forming hypophosphorous acid solution in the product compartment.Because of the cationic exchange membrane resistant, the hypophosphite ions did notenter into anodic compartment so as not to contact with oxygen liberated from anode,therefore the hypophosphite ions did not be oxidized. The following equations arereactions in anodic compartment, product compartment and cathodic compartment,respectively.Anodic compartment :2H2O=4H++O2↑+4eProduct compartment:H++ H2PO2- =H3PO2Cathodic compartment:2H2O+ 2e=2OH +H21Na*+OH = NaOHThe reagents and preliminary concentration of various compartment electrolyte are asfollows: 10 g/L sulfuric acid (anolyte), 10 g/L hypophosphorous acid (productcompartment), 400 g/L hypophosphite sodium solution (material compartment), 10 g/Lsodium hydroxide (catholyte). The black lead, Ti-PbO2, and Ti-Ru electrodes arecustom-made.Black lead, Ti-PbO2, and Ti-Ru were used as anodes and stainless steel was used ascathode. The electrodialytic cell ran for three hours. The electrode area was 40 cm2 andcurrent density was 30 mA/cm'. To make sure the penetrability and lifetime of the ionexchange membranes, the electrolyte temperature was kept below 40°C by using thecooling devices. Saturated calomel electrode was inserted into the anolyte as a referenceelectrode, keeping the constant distance between saturated calomel electrode and anode.During the electrolyzing, the anodic voltage between reference electrode and anode wasmeasured continuously with potentiometer. The variation of anodic voltage with run timeis shown in Figure 2Figure 1 The four compartments electrodialytic cellAnodeCCathode| OHAnodicProdcutMaterialCathodiccompartment compartment compartment compartment中国煤化工MHCNMH G.Selection of Anodic Material Used in Electrolytic Process1489Figure 2 Variation of anodic voltage with run time◆black lead anode+Ti PbO2 anode-▲Ti-Ru anodeI 0.5run time (hFigure 3 Variation of product (hypophosphorous acid) concentration with run time1208310086(- 1 Ti PbO2 anode4士-Ti-Ru anodeFigure 4 Variation of current efficiency of product compartment with run time80%E 60%” 509◆+ FTi PbO2 anode5 20%; 10%)%621C12run time (H中国煤化工MHCNMH G.1490Fu Sheng WANG et al.After 3 hours, the anodic voltages of black lead electrode, Ti-PbO2 electrode andTi-Ru electrode decreased from 1.839V, 2.19V and 1.99 V to 1.444 V, 1.589 V and 0.418V, respectively (Figure 2). Therefore, the electric energy consumption of Ti-Ruelectrode is the least among these electrodes. The electric energy consumption ofTi-PbO2 electrode is a lttle more than that of black lead electrode.The electrodialytic cell then ran for 12 hours while other above conditions were kept.The variation of production concentration and current efficiency of product compartmentwith run time is shown in Figure 3 and Figure 4.As shown in Figure 3 and Figure 4, after running for 12 hours, the productconcentration for Ti-Ru, Ti-PbO2, and black lead are 97.58 g/L, 93.76 g/L and 81.95 g/L,respectively. The current efficiency of product compartment for Ti-Ru, Ti-PbO2, andblack lead are 49.54%, 47.95% and 41 59%, respectively. In comparing the productconcentration and current efficiency of product compartment, it is easy to deduce that theperformance of Ti PbO2 anode is better than black lead anode and close to Ti- Ru anode.Using electrodialytic cell applying Ti-PbO2 as anode and running for 12 hours, thehypophosphorous acid was enriched. The density and concentration of the enrichedhypophosphorous acid are 1.26 g/mL and 56.8% respectively. The values of varioustargets in the enriched hypophosphorous acid are shown in Table 1. The product(enriched hypophosphorous acid) accords with the demand of analytical reagent.Table 1 The values of various targets in the enriched hypophosphorous acidItemValue (%)cr0.004so,2-0.05HPO0.689NaH2PO20.55Heavy metal (Pb)0.0008As discussed above, within various aspects, Ti-PbO2 electrode is an optimal anodeand should be fitful for extensive industrial application in china.ReferencesY. Song, Tianjin Chemical Industry, 1995, (5), 11.A. Gregory, D. Kirk, U S Patent, 4265866, 1981.N. Fred, B. William, T. Donald, et al., U s patent, 5480517, 1996.4. J. Z. Cheng, Y. Z. Zhang, B. G. Zhang et al, Ion Exchange and Adsorption, 2001, 17(3), 271.5. J. Z. Cheng, Y. Z. Zhang, B. G. Zhang et al., Chinese Journal of Reactive Polymers, 2001, 10B. G. Zhang, Y. z. Zhang, J. z. Cheng, China Patent, 01142024.3, 2001.7. T. Zheng, Q. Y. Dong, Quanmian Fushi Kongzhi (Corrosion Control Completely, in Chinese),2001, 15 (5), 42.Received 20 October, 2003中国煤化工MHCNMH G.

论文截图
版权:如无特殊注明,文章转载自网络,侵权请联系cnmhg168#163.com删除!文件均为网友上传,仅供研究和学习使用,务必24小时内删除。