Paraquat is the most important herbicide of the bipyridyl group. The aim of the present study was to compare the removal of paraquat herbicide from aqueous solutions using nanoscale zero-valent iron-pumice/diatomite composites. In this study, nZVI was supported with diatomite and pumice. Scanning electron microscopy (SEM) analysis, X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectrometry (FTIR), and specific surface area tests (BET) were used to evaluate the properties of nanoadsorbents. The residual concentration of paraquat in aqueous solution was detected by high-performance liquid chromatography (HPLC). Then, the effects of different variables including the pollutant concentration, contact time, temperature, adsorbents (D-nZVI and P-nZVI) dose, and pH, were investigated in a lab scale batch system. The results showed that the optimal pH for both processes was 3.74. In optimal conditions, the efficiencies of D-nZVI and P-nZVI were 92.76% and 85.28%, respectively. In addition, isotherm and adsorption kinetics studies indicated that P-nZVI follows the Langmuir and Freundlich isotherm models, and D-nZVI follows the Langmuir isotherm model, and both processes follow pseudo-second-order kinetics. The results indicated that the synthesized nanoparticles were suitable for removing paraquat from aqueous solutions. Both adsorbents were found to be very effective in removing similar compounds at ambient temperature in a short time.

中文翻译：

---

使用纳米零价铁-浮石/硅藻土复合材料从水溶液中去除百草枯除草剂的比较

百草枯是最重要的联吡啶类除草剂。本研究的目的是比较使用纳米级零价铁-浮石/硅藻土复合材料从水溶液中去除百草枯除草剂的效果。在这项研究中，nZVI 由硅藻土和浮石支撑。使用扫描电子显微镜 (SEM) 分析、X 射线衍射光谱 (XRD)、傅里叶变换红外光谱 (FTIR) 和比表面积测试 (BET) 来评估纳米吸附剂的性能。百草枯在水溶液中的残留浓度采用高效液相色谱法 (HPLC) 检测。然后，在实验室规模的批量系统中研究了不同变量的影响，包括污染物浓度、接触时间、温度、吸附剂（D-nZVI 和 P-nZVI）剂量和 pH 值。结果表明，两种工艺的最佳 pH 值为 3.74。在最佳条件下，D-nZVI 和 P-nZVI 的效率分别为 92.76% 和 85.28%。此外，等温线和吸附动力学研究表明，P-nZVI 遵循 Langmuir 和 Freundlich 等温线模型，D-nZVI 遵循 Langmuir 等温线模型，并且两个过程都遵循伪二级动力学。结果表明合成的纳米颗粒适用于从水溶液中去除百草枯。发现这两种吸附剂在环境温度下短时间内去除相似化合物方面非常有效。等温线和吸附动力学研究表明，P-nZVI 遵循 Langmuir 和 Freundlich 等温线模型，D-nZVI 遵循 Langmuir 等温线模型，并且这两个过程都遵循伪二级动力学。结果表明合成的纳米颗粒适用于从水溶液中去除百草枯。发现这两种吸附剂在环境温度下短时间内去除相似化合物方面非常有效。等温线和吸附动力学研究表明，P-nZVI 遵循 Langmuir 和 Freundlich 等温线模型，D-nZVI 遵循 Langmuir 等温线模型，并且这两个过程都遵循伪二级动力学。结果表明合成的纳米颗粒适用于从水溶液中去除百草枯。发现这两种吸附剂在环境温度下短时间内去除相似化合物方面非常有效。