刚果红交联聚乙烯醇薄膜／K^＋交换玻璃光波导检测氯化氢气体

用环氧氯丙烷为交联剂合成了刚果红(CR)交联聚乙烯醇(PVA)CR-PVA敏感试剂.用匀胶机将其做成薄膜固定在钾离子交换玻璃光波导表面,研制出一种光波导氯化氢气体传感器.CR-PVA薄膜碱式结构的最大吸收波长在600 nm以下,对波长为632.8 nm的激光吸收很弱;薄膜与酸性气体发生反应后强烈吸收波长在632.8 nm附近的导波或消失波;检测输出光强度的变化,即能够测出酸性气体浓度.测试结果表明,本传感器对低浓度HCl气体有快速响应,且对1.6～192 mg/m3范围内有良好的线性响应;SO2、NO2气体的浓度大于18000 mg/m3时才有响应,而对于高、低浓度H2S气体均无响应.

Detection of Hydrogen Chloride Gas by Congo Red Cross-linked Poly(vinyl alcohol) Thin Film/K+ Ion-exchanged Glass Optical Waveguide

The compound of Congo red(CR) cross-linked poly(vinyl alcohol)(PVA) was prepared and used as a sensitive material.A glass optical waveguide(OWG) hydrogen chloride gas sensor was fabricated by coating a thin film of CR-PVA on the surface of ion-exchanged glass OWG with spin coating.The basic form of the sensitive material absorbs light wavelength below 600 nm,but does not absorb the 632.8 nm He-Ne laser beam.In the presence of HCl gas,CR-PVA film changes its color from red to blue,which allowed the absorption of the 632.8 nm guided wave or envanescent wave on the OWG.Then the HCl gas concentration can be measured by detecting output light intensity change.The results show that the sensor has rapid and good linear response in the range of 1.6-192 mg/m3 HCl gas,and has response to SO2and NO2 gas when the concentration of these gases was higher than 18000 mg/m3.It was found that this sensor has no response to H2S gas even it is concentration was very high.The present sensor has high sensitivity and selectivity with regard to HCl gas,and its characteristic features include low cost,simple structure,and simple fabrication.