Synthesis Catalyst Of ZnCo₂O₄@NF And Its Catalytic Activity On Bisphenol A By Peroxymonosulfate Activation

Bisphenol A（BPA）is widely and enduringly distributed in the environment as a toxic and refractory Environmental Endocrine Disrupting Chemical,which seriously endangers to the environment and the organism health.Sulfate-based Radical Advanced Oxidation Process（SR-AOPs）can generate sulfate radicals(SO₄^·-)with strong oxidation ability to degrade BPA efficiently.In this study,the cobalt zinc bimetallic oxide catalyst was prepared and then loaded on nickel foam（NF）,of which the catalytic performance on activating permonosulfate（PMS）over the degradation of BPA was optimized.A facile and efficient route for controllable synthesis of the cobalt zinc bimetallic oxide catalyst by microwave assisted method was proposed.Different oxidation systems were compared and the results showed that the cobalt zinc bimetallic oxide catalyst/PMS system exhibited the most significant enhancement for BPA degradation.Under this system,four preparation conditions of the as-prepared catalyst were optimized through single-factor experiments and response surface method which was carried out based on single-factor experiments.The results indicated that the removal efficiency of BPA could reach 99.28%over the optimal catalyst by activating PMS when the microwave temperature,microwave time,calcination temperature and calcination time are 70℃,17.6 min,428℃ and 2.86 h,respectively.The optimal catalyst was systematically characterized using various techniques,such as SEM,XRD,BET and XPS.It was illustrated that the catalyst was confirmed to be cubic ZnCo₂O₄with some fine nanoparticles attached to the surface of sheet structure dispersing evenly,possessing mesoporous structure and high specific surface area of 105.90 m²?g^-1.After that,the process study of BPA degradation in aqueous solution in ZnCo₂O₄/PMS system was conducted.With the removal efficiency of BPA as the evaluation index,three process parameters of the catalytic oxidation in the system were optimized.The BPA removal in aqueous solution of 20 mg?L^-1reached almost 100%within 5 min by using 0.2 g?L^-1of catalyst and[PMS]/[BPA]=5 at pH ranging from4.0-9.0.According to the trapping experiments and the EPR test,it was found that the activation process and the generation of radicals happened on the surface of the catalyst and the surface-bound SO₄^·-was the dominant active specie in the BPA removal compared with the surface-bound·OH.According to the recycle experiments,it was proved that the as-prepared catalyst is environmentally friendly and has a high stability and reusability.Finally,the supported cobalt zinc bimetallic oxide catalyst was prepared with nickel foam（NF）as the carrier.The influence of ZnCo₂O₄@NF catalyst loading and preparation conditions were investigated.It was found that when the actual catalyst loading is 6.0%,calcination temperature is 300℃ and calcination time is 3 h,the highest removal efficiency of BPA could reach 89.8%over the supported catalyst by activating PMS;The optimal supported catalyst was characterized with various techniques,such as SEM,XRD and XPS.It was illustrated that ZnCo₂O₄ was successfully imbedded in NF.The process parameters of catalytic oxidation in the ZnCo₂O₄@NF/PMS system were optimized in details.The results showed that BPA can be degraded efficiently when the ratio of[PMS]/[BPA]is 5 at pH ranging from 3.0-9.0.According to the trapping experiments,it was found that the main active species in the ZnCo₂O₄@NF/PMS system are surface-bound SO₄^·-and·OH.According to the recycle experiments,it was proved that the supported catalyst ZnCo₂O₄@NF is efficient and stable and can be easily recycled.