石墨/钒氧化物的制备、表征及其对亚甲基蓝的吸附性能

Preparation, Characterization of Graphite/Vanadium oxide and It’s Adsorption Properties for Methylene Blue Solution

摘要:

以V2O5为原料，石墨粉为还原剂，采用碳热还原法制备石墨/钒氧化物复合材料。以亚甲基蓝为模拟污染物，系统评价了不同还原工艺条件下所制备样品的吸附性能，并选定在还原温度为650℃、还原时间为60min和石墨配比为18.03%的还原条件下所制备的样品进行表征和作为目标吸附剂。采用X射线衍射、扫描电镜、X射线光电子能谱、拉曼光谱、透射电镜和微孔分析对目标吸附剂的微观结构和形貌进行表征和分析。表征结果表明，样品的物相由石墨、VO2和少量V6O13组成，且钒氧化物呈块状、条状和辐射状分散在片层石墨表面；样品颗粒尺寸从几微米到数十微米不等，BET比表面积和孔体积分别为6.84m2/g和0.02cm3/g，且绝大部分孔径分布在介孔和大孔区间。吸附实验结果表明，在pH值为3～8的范围内石墨/钒氧化物对亚甲基蓝均有较好的吸附性能，平衡吸附量均在200mg/g以上；吸附过程符合Langmuir等温线和准二级动力学方程。

Abstract:

The graphite/vanadium oxide composites were prepared by a carbothermal reduction method using V2O5 as the raw material and graphite powder as the reducing agent. The Methylene blue was used as a simulated pollutant, the adsorption properties of the prepared samples in different reduction conditions were systematically evaluated, and the samples prepared at the reduction temperature of 650 ℃, reduction time of 60 min and graphite ratio of 18.03% were selected for characterization and as the target adsorbent. The microstructure and surface morphology were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, high-resolution transmission electronic microscope and BET microporous analysis. The characterization results showed that the phase of the samples consisted of graphite, VO2 and a small amount of V6O13, the vanadium oxides were dispersed on the lamellar graphite surface in the form of lumps, strips and radiations, the particle sizes of the samples ranged from a few microns to tens of microns. The BET specific surface area box pore volumes of the graphite/vanadium oxide were 6.84 m2/g and 0.02 cm3/g, respectively, and most of the pore sizes were distributed in the mesoporous and macroporous regions. The adsorption experiments results showed that the graphite/vanadium oxide had good adsorption performance on methylene blue in the pH range of 3-8, and the equilibrium adsorption amounts were above 200 mg ? g-1. The adsorption process was in accordance with the Langmuir isotherm and quasi-secondary kinetic equations.