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Fe-Zr改性生物炭制备及去除矿井水中硫酸根的关键参数研究

Preparation of Fe-Zr bimetallic modified biochar based on response surface methodology and optimization of key parameters for removing sulfate ions from mine water

  • 摘要: 作为非常规水资源,黄河流域矿井水资源化利用是黄河流域生态保护和高质量发展的关键。目前,黄河中上游各大煤炭企业的外排矿井水中各指标已基本满足地表III类水质标准,但绝大部分排水中硫酸根离子(SO42−)超标(≈300 mg/L)。针对以上问题,制备了Fe-Zr双金属改性银杏叶生物炭(Fe-Zr@GBC),并利用响应曲面法对制备过程中的关键参数(热解温度、热解时间、Fe和Zr的比例等)进行了优化,使用Box-Behnken设计探究多个因素及其交互作用的影响,最终通过静态吸附实验检验了其对矿井水中SO42−的去除效果。结果表明:在热解温度700 ℃,热解时间4.0 h,Zr∶Fe质量比7∶3,球磨时间2.0 h条件下制备的Fe-Zr@GBC对矿井水中SO42−的去除效果最佳;与Design-Expert优化结果(热解时间为5.45 h、热解温度为601.9 ℃、球磨时间为1.75 h)非常接近。对比预测SO42−的去除率(预测值92.36%),静态吸附实验验证的SO42−的去除率为88.38%,模型值与验证值仅差4.3%,说明Design-Expert优化结果可靠性强。在此基础上,探讨了吸附动力学和热力学特性。结果显示:Fe-Zr@GBC对SO42−的吸附过程主要以单层吸附为主,且准二级动力学动力拟合能够很好地模拟SO42−在Fe-Zr@GBC颗粒内的扩散情况,说明Fe-Zr@GBC吸附反应更符合化学吸附。综上,所制备的Fe-Zr@GBC及其对SO42−的高效去除效果,为解决黄河流域外排矿井水中SO42−超标的问题提供了绿色、高效、稳定的新解决思路,为黄河流域生态保护和高质量发展提供技术支撑。

     

    Abstract: As an unconventional water resource, the utilization of mine water resources in the Yellow River Basin is the key to ecological protection and high-quality development of the Yellow River Basin. At present, the various indicators of the discharged mine water from major coal enterprises in the upper and middle reaches of the Yellow River can basically meet the surface III standard, but the majority of the drainage contains excessive sulfate ions (SO42−) (≈300 mg/L). In response to the above issues, Fe-Zr bimetallic modified Ginkgo biloba leaf biochar (Fe-Zr@GBC) was prepared, and the key parameters in the preparation process (pyrolysis temperature, pyrolysis time, Fe and Zr ratio, etc.) were optimized using response surface methodology. Box Behnken design was used to explore the effects of multiple factors and their interactions. Finally, the adsorption and removal efficiency of SO42− in mine water was tested through static adsorption experiments. The results showed that under the conditions of pyrolysis temperature of 700 ℃, pyrolysis time of 4.0 hours, Zr∶Fe mass ratio of 7∶3, and ball milling time of 2.0 hours Fe-Zr@GBC The best removal effect for SO42− in mine water; The results are very close to the Design Expert optimization results (pyrolysis time of 5.45 h, pyrolysis temperature of 601.9 ℃, ball milling time of 1.75 h). Compared with the predicted removal rate of SO42− (92.36%), the static adsorption experiment verified that the removal rate of SO42− was 88.38%, and the difference between the model value and the verification value was only 4.3%, indicating that the Design Expert optimization results have strong reliability. On this basis, the adsorption kinetic and thermodynamic characteristics were investigated. The results show that the adsorption process of SO42− by Fe-Zr@GBC is mainly monolayer adsorption, and the pseudo-second-order kinetic model can well simulate the diffusion of SO42− in Fe-Zr@GBC particles, indicating that the adsorption reaction of Fe-Zr@GBC is more consistent with chemical adsorption. In summary, the prepared Fe-Zr@GBC and its efficient removal effect on SO42− provide a green, efficient, and stable new solution for addressing the problem of excessive SO42− in mine drainage of the Yellow River Basin, and offer technical support for the ecological protection and high-quality development of the Yellow River Basin.

     

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