Influence of Ca2+ on tetracycline adsorption on montmorillonite

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:368

Article

Eugenia Parolo, M.¹  Avena, Marcelo J.²  Pettinari, Gisela R.¹  Baschini, Miria T.¹ 

[1] Univ Nacl Comahue, Fac Ingn, RA-8300 Neuquen, Argentina

[2] Univ Nacl Sur, Dept Quim, INQUISUR CONICET, RA-8000 Bahia Blanca, Buenos Aires, Argentina

关键词: Adsorption;    Intercalation;    Clays;    Tetracycline;    Antibiotics;   

DOI  :  10.1016/j.jcis.2011.10.079

来源: Elsevier

【 摘 要 】

The adsorption of tetracycline (TC) on montmorillonite was studied as a function of pH and Ca2+ concentration using a batch technique complemented with X-ray diffraction and transmission electron microscopy. In the absence of Ca2+, TC adsorption was high at low pH and decreased as the pH increased. In the presence of Ca2+, at least two different adsorption processes took place in the studied systems, i.e., cation exchange and Ca-bridging. Cation exchange was the prevailing process at pH < 5, and thus, TC adsorption decreased by increasing total Ca2+ concentration. On the contrary. Ca-bridging was the prevailing process at pH > 5, and thus, TC adsorption increased by increasing Ca2+ concentration. The pH 5 represents an isoadsorption pH where both adsorption processes compensate each other. TC adsorption became independent of Ca2+ concentration at this pH. For TC adsorption on Ca2+-montmorillonite in 0.01 M NaCl experiments, the ratio adsorbed TC/retained Ca2+ was close to 1 in the pH range of 5-9, indicating an important participation of Ca2+ in the binding of TC to montmorillonite. X-ray diffraction and transmission electron microscopy showed that TC adsorption induced intercalation between montmorillonite layers forming a multiphase system with stacking of layers with and without intercalated TC. (C) 2011 Elsevier Inc. All rights reserved.

【 授权许可】

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