Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (12): 1171-1175.doi: 10.3866/PKU.WHXB20031217

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Study on the Relationship between Charge and Structure of Montmorillonite

Hu Xiu-Rong;Lü Guang-Lie;Gu Jian-Ming;Chen Lin-Shen   

  1. Central Laboratory of Zhejiang University, Hangzhou 310028
  • Received:2003-05-20 Revised:2003-07-22 Published:2003-12-15
  • Contact: Lü Guang-Lie

Abstract: Chemical composition analysis, CEC method, and alkylammonium method were used to study the charge density and distribution of 12 montmorillonite samples coming from different sources. The results show that the total charge of all dioctahedron montmorillonites is between 0.40 to 0.45 eq/[(Al, Si)4O10], but the layer charge and the variable surface charge vary with the ratio of Al/Mg in octahedron. For the montmorillonites with lower layer charge and higher variable surface charge, the occupancy of Al and Mg in the octahedron site is above 1.5 and 0.3~0.4 respectively, while for the montmorillonites with higher layer charge and lower variable surface charge, the occupancy of that is 1.3~1.4 and about 0.3 respectively. Charge that mostly origin from Mg2+ substituting Al3+ in octahedron and Al3+ substituting Si4+ in tetrahedron is mainly related to Mg content and Al/Mg ratio in montmorillonites. Generally, montmorillonites with higher Mg content have higher charge. The difference of Al/Mg ratio and Fe content accounts for the structural variety, charge and physicochemical property of montmorillonites.

Key words: Montmorillonite, Charge density, Alkylammonium, Chemical composition,  Cation exchange capacity(CEC)