太阳光照射浮石负载二氧化钛降解氨氮废水

采用溶胶-凝胶法制备了Ti O_2,并使Ti O_2负载在浮石上制备Ti O_2/浮石光催化剂。用X射线荧光光谱(XRF)、电镜扫子显微描(SEM)和傅里叶红外光谱(FT-IR)表征浮石、Ti O_2及Ti O_2/浮石。在太阳光照射下,用Ti O_2/浮石处理模拟氨氮废水,以废水中氨氮降解率为标准,考察影响氨氮降解因素。结果表明,Ti O_2成功固定在浮石表面,负载率为3.71%;废水中氨氮降解率随太阳光照射时间、废水p H值、催化剂Ti O_2/浮石含量增加而增大。当初始氨氮浓度为500 mg/L、太阳照射180 min、废水p H=11、催化剂Ti O_2/浮石剂量为20 g/L时,氨氮降解率达82.0%,氨氮除去率86.8%,降解产物中未发现污染成分NO_2~-和NO_3~-产生。催化剂再生/催化3次,每次再生后氨氮降解率约下降10.0%。该方法快速、简单、低消耗和产生二次污染少,能有效地降解废水中的氨氮。

Degradation of Ammonia-Nitrogen in Wastewater by TiO2/Pumice Photocatalyst under Solar Light

Photocatalytic degradation of ammonia-nitrogen in simulated wastewater was investigated by the TiO₂/pumice photocatalyst under solar light. TiO₂ prepared by the sol-gel method was used as the photocatalyst and immobilized on porous pumice granules. To optimize the photocatalytic reaction, the effect of the initial concentration of ammonia-nitrogen, pH, reaction time and catalyst loading on the ammonia-nitrogen degradation rate were investigated in an aerated reactor. Also, the morphology and chemical structure properties of the prepared catalysts were characterized by scanning electron microscopy(SEM), X-ray fluorescence spectrometer(XRF) and Fourier transform infrared spectroscopy(FT-IR) analyses. The experimental results indicate that the coating ratio of TiO₂ on pumice is 3.71%; the ammonia-nitrogen degradation rate is increased by increasing the pH value, time of solar light irradiation and dose of TiO₂/pumice. After solar light irradiation for 180 min, a high degradation rate of 82.0% and a removal rate of 86.8% are achieved under 500 mg/L ammonia-nitrogen, pH 11 and 30 g/L TiO₂/pumice. Moreover, the NO^-₂ and NO^-₃ pollutes are not found in degradation products. The photocatalyst can be reused at least three consecutive times with about 10.0% decrease on the ammonia-nitrogen degradation rate. The results suggest that the photocatalytic purification by photocatalysis is a rapid, low consumed and effective method for the degradation of ammonia-nitrogen in wastewater.