基于Er^(3+)∶YAlO_3/TiO_2的可见光催化降解室内甲醛

Photocatalytic Degradation of Indoor Formaldehyde by Er^(3+)∶ YAlO_3/TiO_2 Photocatalyst Under Visible Light Irradiation

为使TiO2能够在可见光下发挥其于紫外激发的高光催化活性降解室内甲醛,采用水热处理法将TiO2与掺杂稀土离子Er3+的上转换发光剂Er3+∶YAlO3结合,制备具有可见光响应的Er3+∶YAlO3/TiO2光催化剂,并对其进行了表征分析。结果表明,TiO2以锐钛矿为主,且Er3+∶YAlO3可有效地将可见光上转换至可激发TiO2的紫外光。在箱式反应器中进行光催化降解气态甲醛,研究了甲醛初始浓度与催化剂用量对甲醛降解效率的影响。结果表明,该光催化反应的假一级反应速率常数(kapp)与甲醛初始浓度成正相关,而随催化剂用量的增加先升高后降低。当甲醛初始浓度为0.058 mg/m3、催化剂用量为0.122 4 g/L时,kapp最大为3.65×10-3min-1。该反应符合Langmuir-Hinshelwood模型,反应速率常数为5×10-8mg/(L·min)。

In order to develop the photocatalytic activity of TiO2 under visible light as that under ultra-violet light to degrade indoor ormaldehyde pollution, a visible light response photocatalyst consisting of TiO2 and upconversion luminescence agent Er3+∶YAlO3 was prepared using hydrothermal treatment method. The photocatalyst was characterized by X-ray diffractometer (XRD) , UV-Vis diffuse reflec-tance spectrophotometer (DRS) and fluorescence spectrometer (FS) . The prepared TiO2 is anatase-dominant. Er3+∶YAlO3 can convert visible light to ultraviolet ( UV) light to expand the absorption range of TiO2 . The upconverted UV light can excite TiO2 effectively to produce active materials with strong oxidation ability. The photocatalyst was applied to degrade gaseous formaldehyde in the sealed reactor, and the effect of initial formaldehyde concentration and photocatalyst dosage on the degrada-tion efficiency of formaldehyde were investigated. The results show that the prepared photocatalyst can efficiently degrade the formaldehyde. The apparent first order reaction rate constant for gaseous formal-dehyde degradation is positively correlated with the initial formaldehyde concentration, but increases first then decreases with the increasing of photocatalyst dosage from 0. 061 2 g/L to 0. 234 8 g/L. When the formaldehyde concentration is 0. 058 mg/m3 and the photocatalyst dosage is 0. 122 4 g/L, the apparent first order reaction rate constant is the biggest of 3. 65 × 10-3 min-1 . The degradation fol-lows Langmuir-Hinshelwood model, and the reaction rate constant is 5 × 10-8 mg/( L·min) .