A new synthesizing method of TiO2 with montmorillonite: Effective photoelectron transfer to degrade Rhodamine B

Montmorillonite (MMT), with many excellent features, such as nano-layered structure, ion exchange ability and high hydrophilicity, could be considered as a kind of modified materials, so it is widely applied in many fields. In this study, novel photocatalyst material-TMC, is synthesized via the method of filling cations, accomplishing with prepared by loading TiO2 on the surface of MMT, which is proposed to remove Rhodamine B (Rh-B) via photocatalytic degradation. In the preparing process, the negative potential of MMT plays an important role in uniformly distributing TiO2 as well as limiting the size of distributed particles. Meanwhile, obtaining more oxygen vacancies could be attributed to optimal by screen calcination temperature. In addition, the specific surface area of TMC is measured to be three times larger than that of single TiO2. Furthermore, coupled with UV-DRS, FT-IR, XPS and PL, it is confirmed that Ti-O-Si bonds have been formed, and the narrowest bandgap (2.79 eV) is formed with the sample that calcinated at 450 degrees C. Meanwhile, the positions of conduction band and valence band with TMC contribute that it reaches higher Fermi level as compared with single TiO2. In addition, the negative potential (on the surface of MMT) acts as effectively extending the recombination time between electrons (e(-)) and holes (h(+)), so that the transferred photoelectrons can directly form O-center dot(2)- to degrade Rh-B that adsorbed on the surface of MMT. Finally, the main free radical scavenging experiment is conducted to indicate that O-center dot(2)- and (OH)-O-center dot are the dominant free radicals that involve in photocatalytic process, and the degradation pathways for Rh-B are speculated with characterization of HPLC-MS.

Automated summary

In this study, a novel photocatalyst material, TMC, was synthesized by loading TiO2 on the surface of MMT to remove Rhodamine B via photocatalytic degradation. The negative potential on the surface of MMT played a crucial role in distributing TiO2 and limiting particle size. Experimental results confirmed that O-center dot(2)- and (OH)-O-center dot were dominant free radicals involved in the photocatalytic process.