Study On The Supported Spinel Catalyst:Preparation And Activation For Peroxymonosulfate To Degrade P-nitrophenol

Organic pollution in water brings great challenges to the environment and human beings.Peroxymonosulfate（PMS）activation technology is a new technology for the treatment of organic pollution in water.The development of efficient PMS catalysts without secondary pollution is a hot research direction.The powder PMS catalyst in the existing research will face some problems in practical application,such as caking,component loss,difficult separation and recovery and so on.In order to overcome these shortcomings,taking the formed activated alumina pellets（Aaps）as the carrier,cobalt aluminate and copper aluminate spinel phases with high stability were immobilized on Aaps by industrialized impregnation method,and the performance and mechanism of different catalysts activating PMS to degrade p-nitrophenol（PNP）were consistently discussed.The crux contents and results are as follows:（1）The main active component of Co Al₂O₄ was immobilized on Aaps,Co Al-Aaps-600 prepared at 600℃and with the addition of Al Cl₃·6H₂O was the best.The addition of Al Cl₃·6H₂O can significantly inhibit the leaching of cobalt ions,which was related to the polyhedral occupation law of ions in spinel.In the batch reaction,when the dosage of catalyst and PMS were 10 g/L and 0.4 g/L respectively,the removal ratio of 100 m L PNP solution with concentration of 10 mg/L reached84.9%,and the removal ratio of TOC reached 52.6%.Under different conditions,Co Al-Aaps-600 showed excellent catalytic performance and low cobalt leaching.In particular,it can continuously treat 60 L PNP solution with PNP concentration of 10 mg/L in a column reactor,and the average cobalt leaching was only 0.2 mg/L.It was found that the valence transition of Co²⁺/Co³⁺was the crux to activate PMS,and the main active substances were sulfate radical and singlet oxygen.（2）The copper-aluminum component was fixed on Aaps.After characterization,it was considered that copper ions were embedded into the lattice ofγ-Al₂O₃,and"surface spinel"phase was formed.The samples were screened by batch experiment,and the optimal conditions were verified by cyclic experiment.The most suitable catalyst Cu Al_1.5-Aaps-600 was obtained at 600℃and the addition ratio of Al Cl₃·6H₂O was 1.5.The effect of reaction conditions on PNP degradation in Cu Al_1.5-Aaps-600/PMS system was studied by innovative column reaction,PMS of 0.6 g/L,p H≈9 and flow rate of 5 m L/min were selected as appropriate reaction conditions,and this condition can maintain the removal ratio of 200 m L PNP solution with a concentration of 10 mg/L at more than 71%.The durability of the catalyst was verified by a long-term column reaction,the reactor can treat more than 15 L PNP solution with a concentration of 10 mg/L,and about 60%of the catalytic activity can be recovered through simple calcination.The dominant active group in Cu Al_1.5-Aaps-600/PMS system was singlet oxygen,and sulfate radical,hydroxyl radical,and superoxide radical were also found.Through characterization and detection,it was speculated that the key mechanism of PMS activation is related to Cu⁺/Cu²⁺and oxygen vacancy.