Abstract:

Infrared spectrum technique was applied to analyzing the changes of surface —OH structures and characteristic adsorption peaks of the
goethite and δ-MnO₂ which had adsorbed Cu²⁺ under different ionic strengths (c(NaNO₃)=0.01—1.0 mol/L). The results show that the surface free —OH participated in the adsorption of Cu²⁺ on goethite and δ-MnO₂, the hydrogen ions of Fe—O—(H) and Mn—O—(H) were replaced by copper ions, resulting in the formation of Fe—O—(Cu) and Mn—O—(Cu). With the ionic strength increasing, —NO₂ from NO^-₃ of NaNO₃ can be attached to the surfaces of goethite and δ-MnO₂. After the adsorption of Cu²⁺, the infrared spectrum of δ-MnO₂ was not changed significantly, but that of goethite was inverse.

Key words: infrared spectrum, goethite, δ-MnO₂, copper ion