无机盐工业
主管:中海油天津化工研究设计院有限公司
主办:中海油天津化工研究设计院有限公司
   中海油炼油化工科学研究院(北京)有限公司
   中国化工学会无机酸碱盐专业委员会
ISSN 1006-4990 CN 12-1069/TQ

无机盐工业 ›› 2023, Vol. 55 ›› Issue (10): 136-144.doi: 10.19964/j.issn.1006-4990.2022-0752

• 环境·健康·安全 • 上一篇    下一篇

响应曲面法优化碳热还原重铬酸钠制备超细氧化铬

张志强1(), 崔康平1(), 陈星1, 李海洋1,2   

  1. 1.合肥工业大学资源与环境工程学院,安徽 合肥 230009
    2.中新联科环境科技安徽有限公司,安徽 合肥 230009
  • 收稿日期:2022-12-22 出版日期:2023-10-10 发布日期:2023-10-16
  • 通讯作者: 崔康平(1969— ),男,博士,教授,研究方向为固体废物处理处置技术;E-mail:cuikangping@hfut.edu.cn
  • 作者简介:张志强(1995— ),男,硕士,研究方向为工业固废资源化;E-mail:zhangzhiqiang500@163.com

Optimization of preparation of ultrafine chromium oxide by carbothermal reduction of sodium dichromate by response surface methodology

ZHANG Zhiqiang1(), CUI Kangping1(), CHEN Xing1, LI Haiyang1,2   

  1. 1.School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China
    2.Zhongxin Lianke Environmental Technology(Anhui) Co. , Ltd. , Hefei 230009, China
  • Received:2022-12-22 Published:2023-10-10 Online:2023-10-16

摘要:

以含铬电镀污泥中分离提取的重铬酸钠为前驱体,采用响应曲面法优化碳热还原法制备了高纯度超细氧化铬,有效避免了传统工艺生产过程中产生大量含铬废弃物而引起环境污染等弊端,实现了铬资源综合利用与零污染物排放目标。考察了n(C)/n(Na2Cr2O7)、反应时间、反应温度对RECr(Ⅵ)[Cr(Ⅵ)还原转化率]的影响,在此基础上运用响应曲面法进行优化选择,并通过热重分析仪、X射线衍射仪等分析手段对反应物及还原产物进行表征分析,探讨了碳热还原机理。实验结果表明:最佳还原条件为n(C)/n(Na2Cr2O7)=4、反应时间为2 h、反应温度为550 ℃,此时RECr(Ⅵ)达到99.947%;各因素对RECr(Ⅵ)影响的显著性由大到小的顺序依次为n(C)/n(Na2Cr2O7)、反应温度、反应时间。碳热还原机理为还原过程中Na2Cr2O7率先被炭黑还原为Cr2O3与Na2CO3,之后熔融状Na2Cr2O7中和Na2CO3生成Na2CrO4,最后Na2CrO4进一步被炭黑还原为Cr2O3。碳热还原反应温度不宜过高,过高的反应温度会促使Cr2O3向NaCrO2转变。在最佳条件下制备的Cr2O3产品纯度达到99%以上、平均粒径为214.246 nm,符合工业三氧化二铬一类优等品指标要求,满足等离子喷涂、铬绿颜料等材料高值化利用需求。

关键词: 碳热还原, 三氧化二铬, 重铬酸钠, 响应曲面法

Abstract:

The high purity ultrafine chromium oxide was prepared by carbothermal reduction method optimized by response surface method using sodium dichromate separated and extracted from chromium-containing electroplating sludge as precursor.It effectively avoided the disadvantages of environmental pollution caused by a large amount of chromium-containing waste produced in the production process of traditional processes,and achieved the goal of comprehensive utilization of chromium resources and zero pollution emission.The effects of n(C)/n(Na2Cr2O7),reaction time and reaction temperature on RECr(Ⅵ) were investigated.On this basis,the response surface method was used to optimize the selection,and the reactants and reduction products were characterized by thermogravimetric analyzer and X-ray diffractometer.The mechanism of carbothermal reduction was discussed.The results showed that the optimum reduction conditions were n(C)/n(Na2Cr2O7)=4,reaction time of 2 h,reaction temperature of 550 ℃,and the RECr(Ⅵ) reached 99.947%.The significant order from big to small of the influence of various factors on RECr(Ⅵ) was:n(C)/n(Na2Cr2O7),reaction temperature,reaction time.The mechanism of carbothermal reduction was that Na2Cr2O7 was first reduced to Cr2O3 and Na2CO3 by carbon black during the reduction process,then molten Na2Cr2O7 neutralized Na2CO3 to form Na2CrO4,and finally Na2CrO4 was further reduced to Cr2O3 by carbon black.At the same time,the reaction temperature should not be too high,too high reaction temperature would promote the transformation of Cr2O3 to NaCrO2.The purity of the prepared Cr2O3 product was more than 99%,and the average particle size was 214.246 nm,which met the first-class quality index of industrial chromium trioxide and met the high-value utilization requirements of materials such as plasma spraying and chrome green pigments.

Key words: carbothermal reaction, chromium oxide, sodium dichromate, response surface methodology

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