The Mössbauer spectra at ambient temperature and 80 K of 57Fe-humic acid complexes,of which were centrifuged or electrodialyzed,were recorded respectively,and the nature of Fe3+,Fe2+ bound with humic acid at different pH values was studied.The Mössbauer spectra and parameters of 57Fe-humic acid slurry at pH 3 fitted by computer show that three doublets(Fig.1 AA',BB",CC') are reasonable.The Fe3+ in the humic acid at pH 3.0 occurs in more than one type of enviroment and high spin forms.The Mussbauer spectrum signal for Fe3+ was observed but not for Fe2+ in the 57Fe-humic acid at pH 1.0.59% of iron doped was detected in the decantate at pH 1.0.It showed that considerable proportion of Fe3+ was reduced to Fe2+ by humic acid at pH 1.0,but no Fe2+ bound with humic acid strongly.The Mössbauer spectra for Fe3+,Fe2+ were found in the 57Fe-humic acid samples (pH 2.8) which were electrodialyzed at 30 V.This indicates that a part of Fe3+ is reduced to Fe2+.Owing to the decrease of pH of 57Fe-humic acid complexes suspension in the process of electrodialysis,considerable proportion of Fe2+ was bound with humic acid at pH 2.8 strongly.According to Mössbauer spectra recorded at 80 K,there is evidence for magneticallyordered component in the range of the pH 1-3 but no evidence for that at ambient temperature.
邢光熹,张汉辉,韩勇.应用穆斯堡尔(Mössbauer)谱学方法研究Fe+++, Fe++与胡敏酸结合的性质[J].土壤学报,1987,24(3):218-225. Xing Guangxi, Zhang Hanhui, Han Yong. STUDY ON THE NATURE OF Fe3+ AND Fe2+ BOUND WITH HUMIC ACID BY MÖSSBAUER SPECTROSCOPIC METHOD[J]. Acta Pedologica Sinica,1987,24(3):218-225.复制