混晶纳米TiO2的制备及其光催化降解有毒有机污染物

Preparation of Mixed Crystal TiO_2 Nanoparticles and Photocatalytic Degradation of Toxic Organic Pollutants

以无定形TiO2沉淀为前驱体,在水热条件下得到了含板钛矿(121)相混晶纳米TiO2,考察了水热反应的温度和时间等因素对含板钛矿型TiO2光催化活性的影响.采用XRD、TEM对制备的TiO2进行初步表征,并结合光催化(λ≤387 nm)降解有机染料的光活性探针反应.结果表明,水热温度为150℃,时间为24 h时,可制得具有较高光催化活性的纳米TiO2,其纳米尺寸为14.20 nm,板钛矿相含量63.6%,锐钛矿含量为36.4%.光催化实验中跟踪研究了其对染料酸性桃红(sulforhodmineB,SRB)的褪色及2,4-DCP的降解情况,并对降解中间产物H2 O2、.OH进行跟踪测定,实验结果表明板钛矿相混晶TiO2的光催化主要涉及.OH氧化历程,光照射9 h对SRB和2,4-DCP的矿化氧化分别达到89%和78%,循环5次光催化降解SRB实验,催化剂表现出较好的稳定性,催化性能无明显变化.

Mixed crystal TiO2 nanoparticles were prepared from a precursor of TiO2 by hydrothermal-steam method.The effects of the reaction temperature and the reaction time on the photocatalytic activity of the brookite TiO2 were studied.The TiO2 samples were characterized by X-ray diffraction（XRD） and transmission electron microscopy（TEM）.Photocatalytic degradation of organic dye sulforhodamine B（SRB） under UV light（λ ≤387 nm） was used as probe reaction to evaluate the properties of the TiO2.The result showed that TiO2 prepared under 150℃ for 24 h had high photocatalytic activity.The size of the mixed crystal TiO2 was 14.20 nm.Brookite and anatase phase of the mixed crystal TiO2 were 63.6% and 36.4%,respectively.The dye discoloration and degradation rates were tracked,and the intermediate products hydrogen peroxide（H2 O2） and hydrogen radicals（.OH） were determined during the photocatalytic experiments.The results indicated that photocatalytic degradation of brookite TiO2 mainly referred to the.OH radical mechanism.After 5 h,the mineralization and oxidation rates of SRB and 2,4-DCP mineralization were 89% and 78%,respectively.The catalyst showed good stability with no significant changes in catalytic properties after 5 cycles of SRB photocatalytic degradation experiments.