Preparation, Characterization And Photocatlytic Activity Research Of Doped TiO₂ On Wastewater Containing Polymer

In order to research feasibility of TiO₂ photocatalytic degradation partially hydrolysis polyacrylamide (HPAM), anatase nanocrystallin TiO₂ was prepared by sol-gel method. The conditions of synthesis catalyst were studied according to effect of photocatalytic degradation HPAM solution of containing oil waste. The results show that the best reaction conditions were gained: when calcination temperature is 500℃, catalytic activity achieved high; The optimal aging time is about 1 day; When ratio of Ti(OBu)4 and alcohol is 1:8, ratio of Ti(OBu)4 and water is 10:4 photocatalytic activity of as prepared TiO₂ is highest.Doping is in favor of enhancing photocatalytic activity of TiO₂. Firstly, the mesoporous TiO₂ was prepared from a poly(ethylene glycol)-poly(propylene glycol)-based triblock copolymer (P123), titanium isopropoxide and H₃PW₁₂O₄₀ by using sol–gel and solvothermal method. The structure of as-synthesized composites were Characterizaed by UV/DRS, FT-IR,XRD, solid Raman and ICP-AES. The results show the as-prepared compositions exhibited anatase and brookite phase structure, larger BET areas, and mesoporosity with uniform pore size distribution. It also indicated that the primary Keggin structure remained intact after immobilization of the unit into TiO₂ network, and chemical interactions between the unit and the TiO₂ network existed in the composites. The composites exhibited UV-light photocatalytic activity to degradation of MO, RB, MB and CV and visible-light activity to degradation CV. The intermediates and the final products of CV degradation were detected by ES-MS. According to the experimental results, we proposed a possible mechanism of the photodegradation of CV under UV-light irradiation in the aqueous system. Afterwards, rare-earth oxide doped titania nanocomposites (RE³⁺/TiO₂, where RE³⁺ = Eu³⁺, Pr³⁺, Nd³⁺, Gd³⁺, and Y³⁺) were prepared by a single step sol-gel-solvothermal method. The products exhibited anatase phase structure, nanosized with average size of 9 nm, and rare erath entered into the crystal cell of TiO₂ (interstitial mode) in the form of oxide. Furthermore, the photocatalytic activity of prepared RE³⁺ doped TiO₂ was studied by degrading HPAM under UV light irradiation. The results showed that the enhanced photocatalytic activity was obtained on Eu³⁺ (Gd³⁺, Pr³⁺)/TiO₂. HPAM was completely degraded and maximal mineralization ratio reached 67% when Eu³⁺, Gd³⁺ and Pr³⁺ loading were 2.4% (w). In addition, intermediate products were detected via liquid chromatography/mass spectrometry/ mass spectrometry, and degradation mechanism was analyzed. The photocatalytic degradation of HPAM has been studied in the presence of UV light under different conditions such as pH, catalyst concentration, substrate concentration, Na₂CO₃, NaHCO₃ and NaCl concentration. The degradation of HPAM was found to be strongly influenced by all the above parameters except for NaCl concentration. Increasing reaction time, optimal concentration of catalyst, pH≈6 and lower substrate concentration are in favor of photocatalytic reaction.