Cu-Al_2O_3中骨架铜类芬顿催化去除水中有机污染物

Fenton-like Catalytic Removal of Organic Pollutants in Water by Framework Cu in Cu-Al_2O_3

为解决传统铁基芬顿催化剂在水体通常酸碱(pH>6)条件下活性低的问题,采用简单共沉淀法制备了Cu掺杂的Al_2O_3类芬顿催化剂.通过X射线衍射(XRD)、X射线光电子能谱(XPS)和紫外可见(UV-vis)吸收光谱分析表明,Cu-Al_2O_3中铜掺杂的质量分数低于4.77%时,催化剂中铜主要以Cu^(2+)和Cu^+的形式共存于Al_2O_3的骨架结构中,形成Al—O—Cu键;过量的铜掺杂会导致外骨架铜物种如铜氧化物团簇的存在.以难降解有机污染物2-氯苯酚(2-chlorophenol,2-CP)和染料罗丹明B(Rhodamine B,Rh B)为目标污染物,对Cu-Al_2O_3的类芬顿催化性能进行了详细地研究.结果表明,骨架铜物种在中性温和条件下对2-CP和Rh B显示出很高的催化去除效率和稳定性,反应2 h,Cu-Al_2O_3(Cu质量分数4.77%)对2-CP的去除率达到54%,相应的TOC去除率达到49%,而铜离子溶出浓度仅为0.025 5 mg·L-1,而Cu-Al_2O_3(Cu质量分数7.58%)由于外骨架铜的存在导致催化活性增加缓慢和稳定性下降.ESR测试结果表明,·OH和HO_2^-/O_2^-·是反应中主要的活性物种.

To address the problem of low activity for Fe-based Fenton-like catalysts at neutral pH,Cu-Al2O3Fenton-like catalyst was prepared by a simple co-precipitation method. The samples were characterized by means of X-ray diffraction（ XRD）, X-ray photoelectron spectroscopy（ XPS） and diffuse reflectance UV-vis spectra（ UV-vis DRS）. The results showed that both Cu2 ＋and Cu＋mainly existed in the bulk framework of Al2O3 for Cu-Al2O3 with appropriate Cu doping（ lower than 4. 77% Cu）,forming the bond of Al—O—Cu,while excessive Cu doping in Al2O3（ e. g. 7. 58% Cu） could result in the occurrence of extraframework Cu species. The Fenton-like catalytic performance of the prepared samples was evaluated by the degradation of 2-chlorophenol（ 2-CP） and Rhodamine B（ Rh B）. The results showed that the catalyst with framework Cu species had high catalytic activity and stability for the degradation of 2-CP and Rh B. After reaction for 2 h,the degradation rate of 2-CP reached up to 54% over Cu-Al2O3（ 4. 77% Cu） in the presence of H2O2,the corresponding TOC removal reached 49%,and the Cu release concentration was only 0. 025 5 mg·L- 1. However,the existence of extraframework Cu in Al2O3 would lead to the reduction of the catalytic performance. ESR analysis showed that ·OH and HO2-/ O2-·were the primary active species.