Pedosphere 5(3): 229--235, 1995
ISSN 1002-0160/CN 32-1315/P
©1995 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Transformation of coordinate forms of phosphate adsorbed on goethite surfaces under conditions of varying pH
JIE Xiao-Lei1, LIU Fan1, ZHOU Dai-Hua1, XU Feng-Lin1, LI Xue-Yuan1 and WANG Dian-Fen2
1 Hnazhong Agricultural University, Wuhan 430070 (China)
2 Wuhan University of Technology, Wuhan 430O70 (China)
ABSTRACT
      X-ray photoelectron spectroscopy (XPS) and automatic titrimeter were used to study the relation between pH and the transformation of the coordinate forms of P on goethite surfaces. The results showed that for a given P concentration, increasing the pH of suspension could cause a fast transformation of monodentate complexes of phosphate ions on goethite surfaces to binuclear ones. When lowering the pH, additional adsorption of P occurred and the binuclear complexes reverted slowly to the monodentate ones. The dissociation and association of protons of the sorbed P caused by pH changes was considered to be a major reason leading to the transformation of the coordinate forms of P on the surfaces. The stability of binuclear surface complex of P was greater than that of monodentate complex. The possible reactions on the interface of goethite and solutions with pH changes, and the reasons causing the different stabilities of the two coordinate P complexes are discussed in the paper.
Key Words:  coordinate form, goethite, pH, phosphate, X-ray photoelectron spectroscopy
Citation: Jie, X. L., Liu, F., Zhou, D. H., Xu, F. L., Li, X. Y. and Wang, D. F. 1995. Transformation of coordinate forms of phosphate adsorbed on goethite surfaces under conditions of varying pH. Pedosphere. 5(3): 229-235.
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