A turbidity compensation method for COD measurements by UV-vis spectroscopy
A turbidity compensation method for COD measurements by UV-vis spectroscopy
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DOI：
10.1016/j.ijleo.2019.04.096
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发表时间：
2019-01-01
期刊：
影响因子：
3.1
通讯作者：
Li, Dongbo
中科院分区：
文献类型：
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作者：
Li, Jingwei;Tong, Yifei;Li, Dongbo
在紫外可见分光光度法水质检测中，检测设备面向不同的水体。容易受到悬浮固体颗粒（SSP）引起的浊度干扰，导致整个光谱非线性上升，化学需氧量（COD）测量精度显着下降。研究了一种基于朗伯-比尔定律的紫外可见光谱浊度补偿算法，用于拟合全光谱范围内浊度引起的吸光度。根据吸光度的可加性，通过过滤和差分法得到了一些浊度的吸光度光谱。然后将它们用作基础光谱，以线性拟合任何浊度值水的吸收光谱。最后通过减法的方法实现了整个区域内所有样品的浊度补偿。与350 nm比例补偿（350 nm PC）和乘性散射校正（MSC）相比，本文方法的补偿光谱与0.45 tun滤光膜的滤光光谱吻合得最好。采用偏最小二乘法(PLS)建立了三种方法的原始光谱和补偿光谱的COD预测模型。结果表明，该方法的Rpred最大，RMSEP最小。实验结果表明，所提出的浊度补偿方法能够有效校正吸收光谱，且不影响水样的吸收特性。此外，提高了紫外可见光谱法 COD 测量的准确性。
In water quality detection by ultraviolet-visible (UV-vis) spectroscopy, the detection equipment faces diverse water bodies. It is easy to be interfered by turbidity caused by suspended solid particles (SSP), resulting in a nonlinear rise of the whole spectrum and a significant decrease in measurement accuracy of chemical oxygen demand (COD). A turbidity compensation algorithm for UV-vis spectroscopy based on Lambert-Beer's law for fitting the absorbance caused by turbidity in the whole spectrum region is studied. According to the additivity of absorbance, a few absorbance spectra of turbidity were obtained by filtering and difference method. They are then used as base spectra to linearly fit the absorbance spectrum of any turbidity value water. Finally, turbidity compensation of all samples in the whole region is realized by the subtraction method. Compared with 350 nm proportional compensation (350 nm PC) and multiplicative scatter correction (MSC), the compensated spectra of the method proposed in this paper are in the best coincidence with the filtered spectra by a 0.45 tun filter membrane. Partial least squares (PLS) method is used to establish the COD prediction model of the raw spectra and compensated spectra of the three methods. The results show that the Rpred of the proposed method is the biggest and the RMSEP is the smallest. The experimental results show that the proposed turbidity compensation method can effectively correct the absorption spectrum without affecting the absorption characteristics of water samples. Furthermore, improving the accuracy of COD measurement by UV-vis spectroscopy.