光催化剂钨酸铋的形貌对罗丹明B吸附行为的热力学研究

Thermodynamic Studies on the Adsorption Processes of Rhodamine B on Bismuth Tungstate Photocatalyst of Different Morphologies

半导体光催化剂的催化活性与其表面吸附密切相关,故吸附过程的热力学行为亟需研究。本研究采用等温滴定量热法(ITC)研究了具有代表性的水污染物罗丹明B(RhB)在三种不同形貌的钨酸铋(Bi_(2)WO_(6))纳米结构(花状、扁球状和片状)表面的吸附过程。利用量热数据计算了吸附过程中重要的热力学参数,包括摩尔吸附焓、吸附平衡常数和单层吸附饱和度等。结果表明,不同形貌的纳米材料表面的吸附过程存在显著差异。从静电力、取向力、水合作用、吸附部位和被吸附分子(或离子)的脱水作用等几个重要的弱相互作用出发,讨论了液固吸附体系的热力学行为。

The catalytic of semiconductor photocatalyst is closely related to its surface adsorption,so the thermodynamic behavior of adsorption process needs to be studied.In this study,nano-watt-scale isothermal titration calorimetry(ITC)was conducted to explore the adsorption process of Rhodamine B(RhB),a representative water pollutant,onto Bismuth Tungstate(Bi_(2)WO_(6))nanostructures of three different morphologies,namely flower-like,pancake-like and sheet-like.Important thermodynamic parameters,such as molar adsorption enthalpies,equilibrium constants of adsorption,and the saturation of monolayer adsorption for the adsorption process of RhB on Bi_(2)WO_(6) nanoparticles have been calculated from the calorimetric data.The results have demonstrated significant differences in the adsorption processes between the surfaces of nanoparticles with different morphologies.The thermodynamic behaviors of the liquid-solid adsorption systems have been discussed in light of several important weak interactions,including electrostatic force,orientation force,hydration,and dehydration of the adsorption sites and the adsorbed molecules(or ions).