太赫兹时域光谱技术的重金属离子吸附检测方法研究

随着工业化进程的不断推进，水体重金属污染问题日益严重。秸秆具有来源广泛、价格低廉、易再生等优点，故成为水体重金属污染处理的理想吸附剂。为研究太赫兹波技术在水体重金属污染检测的应用前景，实验选取原始秸秆和碱化秸秆分别对重金属离子进行吸附，利用太赫兹时域光谱技术(THz-TDS)在室温氮气环境下对原始秸秆样品、碱化秸秆样品、原始秸秆吸附重金属离子样品、碱化秸秆吸附重金属离子样品和碱化秸秆吸附重金属离子解吸后的样品进行光谱测量，秸秆经碱化处理后处于1.75～1.85 THz的杂合吸收峰带吸收系数有明显下降，并伴有肩峰式吸收带后移的现象，在吸附重金属离子后，原始秸秆样品中原有的1.75～1.85 THz杂合吸收带消失，却在1.8～2.05 THz形成了杂合吸收带。碱化秸秆在1.7～2.05 THz呈现复杂的多个肩峰式吸收，而碱化秸秆吸附重金属样品在1.7～2.05 THz呈现平滑的强吸收带，碱化秸秆吸附重金属离子水解吸后吸收谱线近乎平行。结合秸秆及碱化吸附重金属的化学反应过程对吸收谱进行分析，可得到不同组分样品的分子振动及官能团信息，并得到碱化秸秆吸附重金属应为络合吸附和静电吸附两种吸附方式。证明了太赫兹时域光谱技术在水体重金属污染检测中的可靠性和良好的应用前景。

Detection of Adsorption for Heavy Metals Ions Based on Terahertz Time Domain Spectroscopy

With the continuous progress of industrialization, heavy metal pollution in water is becoming more and more serious. Straw has many advantages such as wide availibility, low cost and easy production, which makes it an ideal biological adsorbent to deal with heavy metal pollution.In order to study the application prospect of terahertz wave technology in the detection of heavy metal pollution in water body, original straw and alkaline straw were selected to absorb heavy metal ions. Terahertz time-domain spectroscopy (THz-TDS) was utilized at a room temperature under nitrogen atmosphere to conduct spectral measurement for original straw samples, alkaline straw samples, samples of original straw with heavy metal ions absorbed, samples of alkaline straw with heavy metal ions absorbed, and samples of desorbed alkaline straw. The absorption coefficient of the alkali-treated straw under 1.75~1.85 THz hybrid absorption peak band was significantly decreased, accompanied by an acromion backward shifting phenomenon of the absorption band. After absorbing heavy metal ions, the intrinsic 1.75~1.85 THz hybrid absorption band was disappeared in original straw samples, but formed a hybrid absorption band in the range from 1.8 to 2.05 THz. Alkaline straw in 1.7~2.05 THz presented a number of complex acromino-absorption, while heavy metal ions absorbed alkaline straw showed a smooth and strong absorption band in 1.7~2.05 THz. In addition, the absorption spectrum of the hydrolyzed heavy metal ion absorbed alkaline straw was nearly parallel. Though integrating the chemical reaction process of the samples, absorption spectrum was analyzed, and the information of molecular vibration and functional group of different components were gained. Furthermore, the conclusion that complex adsorption and electrostatic adsorption are the two methods for alkaline straw to absorb heavy metal can be drawn. It proved the reliability and good application prospect of the terahertz time-domain spectroscopy on detecting heavy metal pollution in water.