Adsorption of acid orange 7 on the surface of titanium dioxide
Adsorption of acid orange 7 on the surface of titanium dioxide
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DOI：
10.1021/la051434g
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发表时间：
2005-09-27
期刊：
影响因子：
3.9
通讯作者：
Verykios, XE
中科院分区：
文献类型：
--
作者：
Bourikas, K;Stylidi, M;Verykios, XE
在不同浓度(1 × 10（-4)-3 × 10(-3) M）和PH值（2-10）范围内，广泛研究了模型织物偶氮染料酸橙7 （AO7）在二氧化钛表面的吸附。利用电位滴定、吸附等温线、吸附边和微电泳等多种技术获得的结果，用于描述“AO7溶液/TiO2表面”界面。这是通过考虑PH对溶液中染料形态的影响以及对TiO2表面基团的性质和居群的影响而实现的。使用最近引入的CD-MUSIC方法可以很好地模拟结果。根据所采用的模型，TiO2表面不是均匀的，而是存在不同类型的表面基团，即单（TiOH-1/3）、双（Ti2O-2/3）和三（ti300）协同。表面配合物不被视为点电荷，但它们的电荷在空间上分布在界面区域。研究发现，AO7仅在PH值低于7时，通过偶氮染料的磺酸基，通过形成双齿内球表面配合物，才在TiO2表面上发生显著的吸附。通过非原位FTIR结果对TiO2吸附模式的测定，以及吸附常数K-ads的测定，可以描述AO7吸附在大PH和AO7浓度范围内的PH依赖性。
The adsorption of a model textile azo-dye, Acid Orange 7 (AO7), on the surface of titanium dioxide was extensively investigated in aqueous TiO2 suspensions over wide ranges of AO7 concentrations (1 X 10(-4)-3 X 10(-3) M) and PH values (2-10). Results obtained with the use of a variety of techniques, including potentiometric titrations, adsorption isotherms, adsorption edges, and microelectrophoresis, were used for the description of the "AO7 solution/TiO2 surface" interface. This has been achieved by taking into account the effects of PH on the speciation of the dye in solution and on the nature and population of the surface groups of TiO2. Results could be modeled very well with the use of the recently introduced CD-MUSIC approach. According to the model employed, the TiO2 surface is not considered homogeneous but is characterized by the presence of different types of surface groups, namely singly (TiOH-1/3), doubly (Ti2O-2/3), and triply (Ti3O0) coordinated. Surface complexes are not treated as point charges, but their charge is spatially distributed in the interfacial region. It has been found that adsorption of AO7 on the TiO2 surface occurs to a significant extent only at PH values lower than 7, via the sulfonic group of the azo-dye, through the formation of a bidentate innersphere surface complex. The determination of the adsorption mode of TiO2, which is supported by ex situ FTIR results, as well as of the adsorption constant, K-ads, allowed the description of the PH dependency of the AO7 adsorption over large PH and AO7 concentration ranges.