C掺杂纳米硅藻土@TiO2催化剂吸附-光催化降解油田废水

Adsorption-Photocatalytic Degradation of Oilfield Wastewater by C-doped Diatomite@TiO2 Catalyst

硅藻土@TiO2复合材料已被证明对液态和气态的有机污染物如染料、甲醛等具有较高的吸附能力、光催化活性和重复使用性,而C掺杂则能够调控TiO2的能带结构并拓展其吸收范围至可见光区域。本研究以四氟化钛为前驱体,采用简单的水热合成法制备了硅藻土@TiO2复合材料,并以葡萄糖为碳源,通过焙烧的方法得到C掺杂硅藻土@TiO2光催化剂,探索了C掺杂纳米硅藻土@TiO2在可见光下对油田废水中有机污染物的去除效果。研究表明,C的掺杂并未使硅藻土@TiO2的形貌发生改变,产物保持了丰富的孔隙结构,TiO2颗粒较为均匀地负载在硅藻土上;同时,紫外-可见光谱证实了C掺杂使得材料的禁带宽度明显减小。根据吸附-光催化测试结果,C掺杂量为20%、焙烧时间为3 h的光催化剂样品,在吸附20 min+光照射75 min后可使油田废水的COD降低82.59%,其去除污染物效果显著优于纯硅藻土@TiO2。

D iatomite/TiO2 composites have been proven by sufficient works to have high adsorption capacity and high photocatalytic activity for organic pollutants,e.g.dyes and formaldehyde,as well as good reusability.And carbon doping can help to adjust the band structure of TiO2,and consequently,to extend the absorbing range of TiO2 to the visible light region.In this work,by using titanium tetrafluoride as precursor and appl-ying a simple hydrothermal synthesis method,diatomite@TiO2 composites were prepared,and into which,by using glucose as C source,carbon was then doped so as to prepare C-diatomite@TiO2 photocatalysts via the calcination method.The characterization of the resulted C-diatomite@TiO2 and the COD removal experiment(under visible light irradiation)for oilfield wastewater were carried out,obtaining some useful and satisfactory results.The morphology of C-diatomite@TiO2 changes very little after C doping(compared with diatomite@TiO2),as the porous structure is well retained and TiO2 particles are uniformly distributed on diatomite.UV-vis spectroscopy confirmed the significant reduction of the band gap induced by C doping.Moreover,according to the experiment of 20 min adsorption plus 75 min visible-light-photocatalyzed degradation,the COD of oilfield wastewater can be decreased by 82.59%under the presence of the photocatalyst sample with a carbon doping amount of 20%and a calcination time of 3 hours.This removal efficiency of organic compounds is much higher than that of pure diatomite@TiO2.