赤铁矿和三羟铝石吸附Cu^(2+)的红外光谱研究

FTIR Spectroscopic Analysis of Cu^(2+) Adsorption on Hematite and Bayerite

应用红外光谱法,研究了不同pH值和Cu2+浓度条件下,合成赤铁矿和三羟铝石吸附Cu2+后表面羟基结构及其特征吸收峰的变化。结果表明:(1)随Cu2+浓度增加,赤铁矿表面H—O—H和OH的变形振动参与了吸附反应,Cu2+强烈地缔结在Fe—O上,形成了Fe—O—(Cu)结构。(2)酸性条件下,H+破坏了赤铁矿表面的O—H结构,NO3-促使弱峰1 131 cm-1的产生。随pH值增大,赤铁矿表面OH-逐渐由伸缩振动转变为变形振动,Fe—OH和Fe3+—O2-结构不断发生改变。(3)三羟铝石对Cu2+的吸附发生在高波位,随Cu2+浓度增大,其表面游离羟基的O—H弯曲振动、水分子的OH-伸缩振动和H—O—H弯曲振动均参与了吸附反应,Al—O基中的Al3+渐被Cu2+取代从而加强了较低波位的振动强度。(4)随pH值增加,三羟铝石Al—OH的弯曲振动和Al—O的伸缩振动逐渐发生着改变,表明吸附Cu2+后,在其表面形成了AlOCu+与AlOCuOH结构。

The changes in surface hydroxyl structures and their absorption peaks after the adsorption of Cu2＋ on the hematite and hayerite were studied by FTIR spectroscopy under the different pH values and Cu2＋ concentrations. The result indicated that： （1） with the increase of Cu2＋ concentrations, the H--O--H and OH deformation vibration of the hematite participated in the adsorption and Cu2＋ combined with the Fe--O structure strongly, then Fe^（Cu） had been formed on the hematite surface. （2） In acid conditions, H＋ in the solution destroyed the O--H structure of hematite surface and the existence of NO3- prompted the production of a new peak （1 131 cm^- 1 ）. With pH value increasing, the hydroxy structure of hematite surface changed gradu- ally from stretching vibration to deformation vibration, then the structures of Fe-OH and Fe3＋ O2 constantly changed. （3） The adsorption of Cu2＋ on the bayerite happened in the high wave position. With the Cu2＋ concentration increasing, the free OH bending vibration, the OH- stretching vibration and its H--O--H bending vibration were all involved in the adsorption, and at the same time, AP＋ of Al--O was gradually replaced by Cu2＋ , which enhanced the vibration intensity of the low waves position. （4） With the increase in pH, the Al- OH bending vibration and Al--O stretching vibration changed gradually, which indicated that AlOCu＋ and AlOCuOH structure had been formed on the bayerite surface after the adsorption.