五氯苯酚在赤铁矿表面吸附的红外光谱研究

FTIR Study of Adsorption of PCP on Hematite Surface

由静态实验得到了五氯苯酚在赤铁矿表面吸附的pH等温线,最大吸附量发生在pH值6.0处,赤铁矿等电点pH值8.5处的吸附量为最大吸附量的31%。通过FTIR分析了赤铁矿吸附前后的变化,研究了吸附时五氯苯酚、赤铁矿存在形态和比例,结果表明:(1)α-Fe2O3565 cm-1处特征峰吸附前后未发生改变,吸附发生在赤铁矿表面。(2)pH6.0时,α-Fe2O3表面OH与水形成的氢键产生的伸缩振动峰3 438 cm-1位移到了3417 cm-1,1643 cm-1表面的H—O—H+的弯曲振动峰由于络合反应发生明显的减弱,1050~1100 cm-1处的Fe—OH键峰位移到了950 cm-1且强度增加。五氯苯酚中的1215 cm-1的C—O键伸缩振动峰位移到1122 cm-1,两者之间作用以静电吸附为主。(3)pH8.5时,α-Fe2O3表面OH与水形成的氢键产生的伸缩振动峰3438 cm-1位移到了3428 cm-1,1643 cm-1处弯曲振动峰由于氢键反应发生明显的减弱,1050~1100 cm-1处的H—O—H+的弯曲振动峰位移到了947 cm-1且强度明显增加,两者之间主要是氢键作用。

The adsorption of pentachlorophenol on hematite was studied through adsorption experiments and FTIR analysis. The pH adsorption isotherms of pentachlorophenol onto hematite were obtained by the static state experiments. The largest adsorption quantity occurred at about pH 6. The adsorption quantity at pH 8. 5 of the isoelectric point of hematite was about 31% of the largest adsorption quantity. Fourier transform infrared （FTIR） spectroscopy was used to analyse the change of hematite before and after PCP adsorption, and the species of PCP on hematite. It was discovered that： （1） the typical peak at 565 cm^-1 of the Fe-O bond in α-Fe2O3 did not change before and after adsorption, and the adsorption occurred on the surface of hematite. （2） At pH 6. 0, the stretching vibration peak at 3 438 cm^-1 due to the hydrogen bond formed between O-H on the surface of α- Fe2O3 and water molecules shifted to 3 417 cm^-1. The bending vibration peak of H-O-H^＋ on the surface at 1 643 cm^-1 was weakened because of complex reaction. The peak owing to F^-OH bond was displaced from 1 050-1 100 cm^-1 to 950 cm^-1 with increased intensity. The C-O bond stretching vibration peak of PCP was displaced from 1215 to 1122 cm^-1. The main interaction between PCP and hematite was static electric interaction. （3） At pH 8. 5, the stretching vibration peak of the hydrogen bond formed between O--H on the surface of α-Fe2O3 and water molecules was displaced from 3 438 to 3 428 cm^-1. The bending vibration peak at 1 643 cm^-1 was obviously weakened because of the hydrogen bonding. The H-O-H^＋ bending vibration peak at 1 050-1 100 cm^-3 was displaced to 947 cm^-1 with obviously increased intensity, indicating that the interaction was mainly through hydrogen bond.