Acta Phys. -Chim. Sin. ›› 2006, Vol. 22 ›› Issue (02): 172-177.doi: 10.3866/PKU.WHXB20060209

• ARTICLE • Previous Articles     Next Articles

Effect of Dextran on the Crystallization of Ferric Hydroxide

SUN Zhen-ya; HUANG Jiang-bo   

  1. School of Resource and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, P. R. China; The Center of Research and Analysis of Materials, Wuhan University of Technology, Wuhan 430070, P. R. China
  • Received:2005-08-02 Revised:2005-09-28 Published:2006-01-22
  • Contact: SUN Zhen-ya

Abstract: The initial nucleation and phase transformatin process of the Fe(OH)3 gel in five different mineralization systems with different dextran concentrations(from 0~2.0%(w) and the same [Fe3+]=0.012 mol•L-1) have been investigated. The mineralizational phases in the initial stage were characterized by FTIR, XRD and ICP-AES spectrometry. The results showed that the concentration of Fe3+ ions in supernatant increased suddenly in the third day during aging and then its secondary reduction stage occurred. There were the same chages of pH as [Fe3+] in these process. The initial phases formed in the systems with dextran were mainly β-FeOOH, not α-FeOOH which growing rapidly in the system without dextran. The dextran molecules were adsorbed on the surfaces of iron oxide particles by complexing with Fe3+. The adsorbed dextran molecules would facilitate the phase transformation from β-FeOOH into α-Fe2O3 by a dissolution-recrystallization mechanism. The secondary reduction stage of [Fe3+] corresponded to the process of the phase transformation from β-FeOOH into α-Fe2O3. With the increasement of the concentrations of dextran (up to 2.0%(w)) in solution, the dissolution of β-FeOOH and the formation of α-Fe2O3 in these mineralization systems were accelerated. It was clear that dextran molecules could control the nuclei type and its phase transformation of the Fe(OH)3 gel.

Key words: Biomineralization, Dextran, Ferric hydroxide gel, Transformation, Dissolution-recrystallization