Preparation Of Calcium Molybdate Based Catalyst And Its Catalytic Ultrasonic Degradation Of Dye Wastewater

CaMoO₄ is one of the main materials of scheelite group.It has been widely used in tetrahedral molybdate unit because of its high chemical stability and strong and wide charge transfer zone.At present,the study on the acoustic catalytic performance of CaMoO₄ has been few reported.The application of CaMoO₄ in the degradation of dye wastewater by acoustic catalysis was studied.Firstly,the CaMoO₄ semiconductor nanomaterials were synthesized by hydrothermal synthesis.The products were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）and UV visible diffuse reflection（DRS）.The results show that the surface area of the synthesized CaMoO₄,the particle size is mainly in the nanometer level and has excellent photosensitivity.Secondly,the synthesized CaMoO₄ semiconductor nanomaterials were used as acoustic catalysts for the degradation of golden orange II（AO7）by ultrasonic catalysis.The photocatalytic activity of CaMoO₄ was investigated by taking the absorbance of AO7 solution as the index before and after ultrasonic degradation.The results show that the degradation effect of AO7 solution is the best when the p H=7,the amount of CaMoO4 is 1 g/l,the initial concentration of AO7 solution is 5 mg/l,the initial p H of AO7 solution is 5,the ultrasonic power is 200 W and the ultrasonic time is 120 min.In addition,the mechanism of ultrasonic catalytic degradation was deduced by adding different active component scavengers to identify the ROS species produced in the process of AO7 degradation,including·OH,·O₂^-,and h⁺.The reusability of CaMoO₄ catalyst was investigated.After four times of recovery,the degradation rate decreased by 5.58%.The stability of CaMoO₄ catalyst in the process of AO7degradation was verified by XRD,XPS and ICP-MS.Finally,the p-n heterojunction（molar ratio of 1%,5%,10%,15%,20%）of the p-n heterojunction with Ag₂O was constructed on the basis of CaMoO4 to enhance its ultrasonic catalytic activity.Ag₂O-CaMoO₄ was characterized by XRD,SEM,XPS and DRS.The Ag₂O-CaMoO₄ heterojunction was used as the acoustic catalyst for the degradation of crystalline violet（CV）by ultrasonic catalysis.The photocatalytic activity of Ag₂O-CaMoO₄was investigated by taking the absorbance of CV solution as the index before and after ultrasonic degradation.When the molar ratio of Ag₂O-CaMoO₄ heterojunction is 10%,the addition of Ag₂O-CaMoO₄ is 1 g/l,the initial concentration of crystal violet solution is 5 mg/l,ultrasonic power is 200 W and ultrasonic time is 120 min,the maximum degradation rate of CV solution is obtained.Secondly,the effect of different active component scavengers（D-Man,L-AA,EDTA-2Na and N₂）on the degradation rate of crystal violet was studied.The results showed that h+was the main ROS in the degradation process of crystal violet,and the degradation process of·OH and·O₂^-also played a role in the degradation process of crystal violet.Finally,the recovery and reuse experiments proved that 10%Ag₂O-CaMoO₄ was used to accelerate the degradation of crystal violet The chemical agent has good reusability and stability.