Study On Visible-light Photocatalytic Remove Of Cr(?)-Containing Organic Wastewater Upon Novel Photocatalytic Composite

Photocatalytic technology is a kind of green technology for water treatment,which can remove and recycle heavy metals while mineralize and remove refractory organics.The core of photocatalysis technology is to develop photocatalyst with high visible light response and improve the utilization ratio of sunlight.In this study,CsPMo/Bi₂O₃ was synthesised by etching-precipitation method.The results shown that Bi₂O₃ was successfully complexed with CsPMo forming Bi₂O₃-CsPMo heterojunction.Besides,both the photocurrent and photogenerated eletron transfer rate were increased.Photocatalytic activity of CsPMo/Bi₂O₃ was investigated on visible light irradiation.The degradation rate of phenol on CsPMo/Bi₂O₃ was Ca.2.68 times that of Bi₂O₃.Mechanistic study suggests that superoxide radical plays a major role,while hydroxyl radical and hole play surpporting role in the process of photocatalytic degradation of phenol on CsPMo/Bi₂O₃.Furthermore,AgI/BiOI-Bi₂O₃ with multi-heterojunctions was prepared using simple etching-deposition process.Different characterization techniques were performed to investigate the structural,light absorption and electrical properties of the as-prepared photocatalysts.It was found that the ternary AgI/BiOI-Bi₂O₃ composite exhibited:improved photocurrent response,smaller band gap,greatly reduced charge transfer resistance and negative shift of flat band potential,which finally led to easier generation and more efficient separation of photo-generated electron-hole pairs at the hetero-interfaces.Thus,for reduction of Cr?VI?,AgI/BiOI-Bi₂O₃ exhibited excellent photocatalytic activity under visible light irradiation at near neutral pH.The optimal AgI/BiOI-Bi₂O₃ was found to be when the initial molar ratio of KI to Bi₂O₃ and AgNO3 to Bi₂O₃ was 1:1 and 10%,respectively.The estimated kCr???on optimized AgI/BiOI-Bi₂O₃ was about 16 times that on pure Bi₂O₃.Good stability was also observed in cyclic runs,indicating that the current multi-heterostructured photocatalyst is highly desirable for the remediation of Cr?VI?-containing wastewater.AgI/?-Bi₂O₃-Bi₂O₂CO₃ with multi-heterojunctions was also prepared using etching-deposition and calcination processes.XRD and FT-IR were used to characterize the structure.Besides,SEM,XPS,and UV-Vis-DRS were used to test the morphology,surface spectroscopy,and light absorption.It can be found that:?1?Agl,?-Bi₂O₃,and Bi₂O₂CO₃ were successfully complexed,?2?calcination temperature can significant affect the activity of AgI/?-Bi₂O₃-Bi₂O₂CO₃ and 325 ? was the optical temperature during the test range,?3?visible light absorption was greatly increased.The photocatalytic activity was also investigated by simultaneous of Cr?VI?and phenol.The result suggested that Cr???and phenol were well removed.