The comparison of direct oxidation process and electrodialysis process for preparing polyferric sulphate

doi:10.16085/j.issn.1000-6613.2017-0232

Abstract

Abstract: Two different processes for preparing polyferric sulphate(PFS) were investigated and compared. Firstly,PFS was generated through direct oxidation process with ferrous sulfate and sulfuric acid as raw materials,and with the potassium chlorate as oxidizing agent. The effect of reaction temperature,reaction time,and the molar ratio of ferrous sulfate to sulfuric acid in raw materials on basicity was investigated. Results showed that basicity improved from 7.68% to 9.34% when reaction temperature increased from room temperature to 70℃. As the molar ratio in raw materials increased from 2.01 to 4.08,basicity increased from 8.65% to 11.91%. However,The increase of the reaction time did not improve the basicity. Secondly,ion exchange membrane electrodialysis was used to prepare PFS. The effects of current density and membrane stack configuration on basicity were investigated. Results showed that the basicity increased from 7.68% to 20.13% remarkably when current density increased from 0 to 30mA/cm². And basicity was not affected by membrane stack configurations. Compared with BP-A configuration,BP-A-C configuration could decrease membrane stack voltage drops and energy consumption. Thirdly,the two processes were compared in terms of PFS performance and production cost. Results showed that the performance of PFS generated by electrodialysis process was better than that of PFS generated by direct oxidation process,while the former cost was 1.16$/L PFS higher that the latter cost.

Key words: ion exchange, membrane, coagulation, chemical reaction

摘要： 究并比较了制备聚合硫酸铁（PFS）的两种不同工艺。首先，使用直接氧化法制备PFS，主要考察反应温度、反应时间、原料中硫酸亚铁和硫酸的摩尔比对产品盐基度的影响，研究结果表明当反应温度从室温增加到70℃，盐基度由7.68%增加到9.34%；当原料摩尔比从2.01增加到4.08，盐基度从8.65%增加到11.91%；延长反应时间不能提高盐基度。其次，使用离子膜电渗析法制备PFS，主要考察电流密度和膜堆构型对产品盐基度的影响，研究结果表明电流密度从0增加到30mA/cm²，盐基度从7.68%显著增加到20.13%；改变膜堆构型不影响PFS的盐基度，但是相比BP-A膜堆构型，BP-A-C膜堆构型可减少过程能耗。最后，从产品性能、生产成本两方面比较两种制备工艺，结果表明离子膜电渗析法制得的PFS性能优于直接氧化法的产品性能，但生产成本至少高出1.16$/LPFS。

关键词: 离子交换, 膜, 混凝, 化学反应

CLC Number:

TQ028.8

CHEN Qianru, WANG Xiaoyao, WANG Tingting, LIU Xiaorui, ZHANG Xu. The comparison of direct oxidation process and electrodialysis process for preparing polyferric sulphate[J]. Chemical Industry and Engineering Progress, 2017, 36(10): 3800-3806.

陈倩如, 汪小尧, 汪婷婷, 刘晓瑞, 张旭. 直接氧化法和离子膜电渗析法制备聚合硫酸铁工艺的比较[J]. 化工进展, 2017, 36(10): 3800-3806.

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