水杨酸和5-磺基—水杨酸表面修饰纳米TiO_2吸附去除对硝基苯酚

Surface-modification of titanium dioxide nanoparticles with salicylic acid & 5-sulfosalicylic acid to remove p-nitrophenol by adsorption

利用化学吸附法合成了水杨酸和5-磺基—水杨酸表面修饰的TiO2纳米粒子.对表面修饰前后的TiO2纳米粒子,采用红外光谱法、固体紫外-可见漫反射电子光谱法比较其官能团和吸光性能的变化.研究发现,经水杨酸和5-磺基—水杨酸改性后的TiO2分别呈浅黄色、土黄色,吸收带边发生了明显的红移,吸收边起始点分别延伸至420nm和450nm处,出现—COOTi—和芳香羧酸酯的特征吸收峰;这说明TiO2表面羟基与水杨酸或5-磺基—水杨酸间发生类似酸和醇之间的酯化反应,分别形成的稳定六元环化合物;在最佳吸附pH值4.0和吸附平衡时间100min的条件下,水杨酸和5-磺基—水杨酸表面修饰的TiO2纳米粒子对硝基苯酚的吸附率可由改性前的43%分别提高至89%和94%,突破了TiO2吸附去除芳香族污染物的瓶颈——在吸附剂表面的低覆盖率;同时表层链接苯环的极性减弱,非极性增强,并在水、苯和乙醇中具有良好的分散性.

Nanometer size titanium dioxides modified by salicylic acid （SA） and 5-sulfosallcylic acid （5-SA） were prepared by using sudace-modification method. Infrared spectroscopy （IR） and UV-Vis reflectance spectra were used to investigate the structure of the modified TiO2 nanopacficles and their absorption spectrum. Effects of modification on the adsorption of p-nitmphenol （PNP） and dispersion in water, benzene and ethanol were also studied. The salicylic acid or 5-sulfosalicylic acid is bonded to the surface of TiO2 nanoparticles, resulting in the formation of a stable, surface sixring complex which color is, respectively, buff and yellow. Through surface modification, the formation of Ti^Ⅳ-SA and Ti^Ⅳ-5-SA surface complex results in a red shift of UV-Vis reflectance spectra, towards the visible region, up to 420 and 450 nm, respectively. Under the optimum pH value 4.0, the adsorption rate of PNP by TiO2 was improved from 43% to 89% and 94%, respectively, through modification by SA and 5-SA. The SA-modified TiO2 and 5- SA-modified TiO2 nanoparticles have good dispersive capacity in water, benzene and ethanol.