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Article

Surface Chemical Modification of Nanosized Oxide Particles with a Titanate Coupling Reagent in Isopropanol

Xiao-Yong Fang, Ting-Jie Wang,* Hai-Xia Wu, and Yong Jin

Department of Chemical Engineering, Tsinghua University, 100084 Beijing, China

Ind. Eng. Chem. Res., 2008, 47 (5), pp 1513–1517

DOI: 10.1021/ie0710824

Publication Date (Web): February 8, 2008

Corresponding author. Tel.: +86-10-62788993. Fax: +86-10-62772051. E-mail: wangtj@mail.tsinghua.edu.cn.

Abstract

The function of the hydroxyl on particle surface in chemical modification in isopropanol with titanate coupling reagent CA7 was investigated. Four kinds of nanosized oxide particles: anatase TiO₂, rutile TiO₂, γ-Al₂O₃, and monoclinic ZrO₂, were used in experiments. The effects of different crystal structures of polymorph TiO₂ on the chemical modification, i.e., anatase and rutile TiO₂, were studied. Fourier tranform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric (TG) analyses showed that the surfaces of anatase TiO₂, γ-Al₂O₃, and monoclinic ZrO₂ were chemically modified, and the quantities of CA7 reacted on particle surfaces were 1.66, 1.79, and 4.29 molecule nm^-2, respectively. It was difficult to chemically modify rutile TiO₂. The hydroxyl groups on anatase TiO₂ have IR adsorption bands at 3714 and 3672 cm^-1. The 3714 cm^-1 hydroxyl reacted with CA7. The hydroxyl on rutile TiO₂ particle has a frequency of 3739 cm^-1, but this did not react with CA7. XPS analysis showed that the binding energies of the oxygen and metal atoms on the modified oxide surfaces were increased. It was inferred that the hydroxyl group has its proton displaced to form a Me−O: species that, together with existing Me−O: on the particle surface, reacted with CA7 to form a Me−O−Ti bond.