Cu-Al2O3中骨架铜类芬顿催化去除水中有机污染物

为解决传统铁基芬顿催化剂在水体通常酸碱(pH6)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.

Fenton-like Catalytic Removal of Organic Pollutants in Water by Framework Cu in Cu-Al2O3

To address the problem of low activity for Fe-based Fenton-like catalysts at neutral pH, Cu-Al₂O₃ Fenton-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 (RhB). The results showed that the catalyst with framework Cu species had high catalytic activity and stability for the degradation of 2-CP and RhB. 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 0.0255 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.