DETERMINATION OF COD IN WATER SAMPLES BY BiVO4/rGO BASED ON PHOTOELECTROCHEMICAL DETERMINATION
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摘要: 准确、及时且环境友好地检测水体的化学需氧量(COD)已成为环境监测领域的重要研究课题。采用溶液燃烧法和旋转涂膜法制备了一种可见光响应型BiVO4/rGO涂膜电极用于COD测定,并考察了该电极用于COD检测的光电化学性能。利用X-射线衍射(XRD)、扫描电子显微镜(SEM)、比表面积分析(BET)探究复合电极结构,表明基底完全被BiVO4/rGO覆盖。采用循环伏安法(CV)、光电流-时间法(I-t)测试其光电性能,确定最佳制备条件为:煅烧温度为500℃、掺杂rGO为5 mL、涂膜厚度为4层。通过考察其测试参数得出,在工作电压为1.0 V、支持电解质为0.1 mol/L Na2SO4、光照强度为400 μW/cm2、pH为6~8可得到稳定可靠的测试结果。利用BiVO4/rGO涂膜电极测定有机物溶液COD的测定范围为12.18~719.8 mg/L,转移净电荷量(Qnet)和理论COD间呈良好的线性关系。用于实际水样COD测定时,在60 s内可达稳态光电流,测定结果与国标法测定COD结果具有良好的一致性,相对偏差均<5%。因此BiVO4/rGO涂膜电极具有响应速度快、线性范围宽、操作便捷等优点,可替代传统COD测定仪器。
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关键词:
- 光电催化反应 /
- BiVO4/rGO涂膜电极 /
- 化学需氧量(COD) /
- 净电荷量 /
- 水处理
Abstract: Accurate, timely and environmentally friendly detection of water Chemical oxygen demand has become an important research topic in the field of environmental monitoring. A visible-light-responsive BiVO4/rGO film electrode was prepared by solution combustion method and rotating coating method for the determination of COD. The structure of the composite electrode was investigated by X-ray diffraction (XRD), surface area analysis(BET) and scanning electron microscope analysis(SEM). The results showed that the substrate was completely covered by BiVO4/rGO. The photoelectric properties were tested by cyclic voltammetry(CV), photocurrent-time (I-t) method, and the best performance was obtained when the calcination temperature was 500℃, the doped rGO was 5 mL, and the coating thickness was 4 layers. The results showed that stable and reliable test results could be obtained in the condition of a working voltage of 1.0 V, supporting electrolyte of 0.1 mol/L Na2SO4, illumination intensity of 400 μW/cm2 and pH of 6~8. The determination range of COD by BiVO4/rGO film electrode was 12.18~719.8 mg/L, and there was a good linear relationship between the transfer net charge (Qnet) and the theoretical COD value. When it was applied to the determination of COD in real water samples, the steady photocurrent could be reached within 60 seconds. The results were in good agreement with the national standard method, and the relative deviation was less than 5%. Therefore, BiVO4/rGO coated electrode has the advantages of fast response, wide linear range and convenient operation, which can replace the traditional COD determination instrument. -
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