College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, People's Republic of China.
Laboratorio de Química de Superficie, Instituto de Metalurgia, Universidad Autónoma de San Luis Potosí, Av. Sierra Leona 550, 78210, San Luis Potosi, Mexico.
Environ Sci Pollut Res Int. 2017 Aug;24(24):20050-20062. doi: 10.1007/s11356-017-9426-2. Epub 2017 Jul 11.
New microscale zero-valent iron adsorbent on fly ash and bentonite matrix for removal of crystal violet (CV) and methylene blue (MB) was synthesized through direct reduction of iron oxide using coke and palm kernel shell. The adsorbent was prepared as cylindrical shaped pellets to remove the CV and MB from the aqueous solution. Nitrogen adsorption-desorption isotherm and scanning electron microscopy (SEM) studies showed that the adsorbent is highly porous, and the iron particles are finely dispersed on the supporting material surfaces. FTIR and UV studies indicated that the C=C bonds in CV and C=N(CH) bonds in MB were affected in the adsorption process. MB switched to the reduced MBH species while CV was reduced to two small-size molecular compounds, explaining the higher CV adsorption in comparison to that of MB. The reduction of these compounds was coupled to the oxidation of Fe to FeO as revealed by XRD characterization of the adsorbent after adsorption. CV and MB adsorption isotherms fitted well with the Langmuir adsorption model. Different adsorption and reduction kinetic models were examined for the MB and CV removal processes. A better fit of the experimental data with the pseudo-second-order model was observed. CV and MB adsorption increased with temperature in the 30-50 °C range. At 50 °C, adsorption capacities of CV and MB reached to 89.9 and 42.8 mg/g, respectively. This new adsorbent showed a superior adsorption capacity for CV and MB when compared to other adsorbents.
通过使用焦炭和棕榈仁壳直接还原氧化铁，合成了一种新型的基于粉煤灰和膨润土基质的微尺度零价铁吸附剂，用于去除结晶紫（CV）和亚甲基蓝（MB）。该吸附剂被制备成圆柱形颗粒，用于从水溶液中去除 CV 和 MB。氮吸附-脱附等温线和扫描电子显微镜（SEM）研究表明，该吸附剂具有高度多孔性，铁颗粒在支撑材料表面上精细分散。FTIR 和 UV 研究表明，CV 中的 C=C 键和 MB 中的 C=N(CH)键在吸附过程中受到影响。MB 转化为还原的 MBH 物种，而 CV 被还原为两个小分子量的化合物，这解释了 CV 的吸附量高于 MB 的原因。这些化合物的还原与 Fe 被氧化为 FeO 耦合，这可以通过吸附后吸附剂的 XRD 表征来揭示。CV 和 MB 的吸附等温线很好地符合 Langmuir 吸附模型。对 MB 和 CV 去除过程的不同吸附和还原动力学模型进行了检验。实验数据与准二级动力学模型的拟合更好。CV 和 MB 的吸附随温度在 30-50°C 范围内增加。在 50°C 时，CV 和 MB 的吸附容量分别达到 89.9 和 42.8mg/g。与其他吸附剂相比，这种新型吸附剂对 CV 和 MB 具有更高的吸附容量。
