Preparation And Adsorption And Photocatalytic Performance Of UiO-66and Its Composites

N-K2Ti4O9was prepared by direct calcination, and N-K2Ti4O9/UiO-66and PANI/N-K2Ti4O9/UiO-66composites were synthesized via self-assembly route. Then theobtained samples were systematically characterized, and their adsorption andphotocatalysis performance were studied. This dissertation is composed of three parts.(1) The adsorption behavior of UiO-66(a Zr-containing metal–organic frameworkformed by terephthalate) for Rhodamine B (RhB) about the isotherms, kinetic andthermodynamic analyses was systematically investigated. The batch adsorption dataconform well to the Langmuir and Freundlich isotherms. The adsorption kinetics ofUiO-66for RhB can be well described by the pseudo first-order model, and the fittedadsorption thermodynamic parameters G0, H0and S0are-6.282kJ/mol,15.096kJ/mol and78.052J/mol·K in273K, respectively. The results of thermodynamicanalyses show that the adsorption process of RhB on UiO-66becomes more favorableat higher temperatures. UiO-66can be regenerated by desorbing in DMF solution alongwith ultrasonic1h. UiO-66can keep good performance for regeneratedsorption/desorption after at least five cycles.(2) N-K2Ti4O9/UiO-66composites possessing a hierarchical core-shell structure withUiO-66forming the shell around the N-K2Ti4O9core were successfully synthesized bya facile solvothermal method at393K for24h.Photocatalytic activity of N-K2Ti4O9,UiO-66and the composites were investigated by the degradation of rhodamine B (RhB)under visible light irradiation,meanwhile, the synergistic effect induced bycompounding was quantitatively evaluated by the proposed synergistic factor. Theresults show that N-K2Ti4O9/UiO-66composites exhibit higher photocatalytic activityas compared with the parent materials due to UiO-66’s good adsorption capacity and theenhanced separation efficiency of photogenerated electron-hole pairs induced bycompounding. In particular, when the molar ratio of N-K2Ti4O9to ZrCl4is3:7, thecomposite exhibits the highest photocatalytic activity, and the synergistic factor is4.90.(3) Via self-assembly route, UiO-66was loaded onto the surface of a low band-gapsemiconductor, N-K2Ti4O9, and then composite photocatalysts ofPANI/N-K2Ti4O9/UiO-66(referred to as Composite A) where polyaniline (PANI) acts asadhesion agent were prepared by in-situ oxidization polymerization, and the ratio ofcomponents was optimized. For comparison, N-K2Ti4O9and UiO-66were prepared separately, and mixed to act as a physical mixture, which were wrapped by PANI anddenominated Composite B. The results show that the core-shell structure was furtherwrapped by PANI to yield PANI/N-K2Ti4O9/UiO-66. Photocatalytic experimentsindicate that PANI wrapping is beneficial to reduce the electron hole recombination rate,and Composite A exhibits the best photocatalytic performance.