Activation Of PMS By Cyclodextrin Modified Amorphous Manganese Oxide For The Degradation Of BPA And Other Pollutants

Up to this day,there are new studies published continuously showing that emerging contaminants(ECS)still exist in surface water in many countries and regions.Although bisphenol A(BPA)is prohibited from food packaging industry in China,its actual requirement is considerable under the huge demand of industry and manufacturing industry,and the toxic risk to human body and environment has never been completely eliminated.Thanks to the rapid and efficient oxidation of organic pollutants by reactive oxygen species(ROS),the activation of persulfate by transition metal is one of the ideal methods to for ECs removal,and manganese oxide has attracted more and more attention as a cheap heterogeneous catalyst.Traditional manganese oxide catalysts often require a high-temperature crystallization processes such as hydrothermal or roasting.The crystal structure is easily affected by the reaction conditions and resulting in different catalytic activities,which increases the cost and complexity of catalyst synthesis.In this study,in order to simplify the preparation process and avoid the factor of crystal phase on the activity,β-cyclodextrin(CD)was introduced into the synthesis of manganese oxide.CD modified amorphous manganese oxide(CD-AM)catalyst was prepared with the oil bath(80℃)to activate peroxymonosulfate(PMS)for the degradation of BPA.The introduction of CD improved the properties and activity of the catalyst:The pore volume is expanded to 5.5 times,the average particle size is reduced by about 53%,the removal efficiency of 20 mg/L BPA in CD-AM/PMS is increased from 33.1%to 99.4%,and the kinetic constant is increased to 14.9 times.In addition to BPA,when[cat]=200 mg/L and[PMS]=1.0 mmol/L,the final removal efficiency of PCMX,2,4-DCP,and SA(20 mg/L)in CDAM/PMS are 93.8%,72.0%,and 45.1%,respectively.With the same conditions,the catalyst prepared by hydrothermal method(CD-AM)provides a poor performance,indicating that crystallization did not mean that one more outstanding performance.1O2 and·OH are the main ROS that degrade BPA in CD-AM/PMS,and O2-produced in this system obviously,which may play an important role in the conversion of ROS and Mn valence cycle.In order to understand the performance and potential of CD-AM/PMS in practical polluted water,the degradation process of BPA under various factors was investigated.In the range of 0.75～1.50 mM of PMS dosage,the degradation efficiency of BPA was stable between 97.46%and 99.41%,indicating a low dependence on PMS dosage.Although the degradation performance of CD-AM/PMS is outstanding under acidic conditions,98.4%BPA removal rate obtained in 30 min under neutral conditions is more conducive to the actual process operation.The effects of cations and humic acids on the degradation performance of CD-AM/PMS can be ignored,while CO32-or HCO3-can lead to an obvious inhibitory effect for the system.In addition,a stable performance of BPA degradation by CD-AM can be observed in the re-cyclic experiment,but there was high leaching concentration of Mn and it was difficult to collect catalysts after experiment.In consideration of the form of "supported membrane"(AMSM),the reusability was further improved and the Mn leaching concentration was reduced effectively.In the treatment of BPA in river surroundings by AMSM/PMS,although the degradation kinetic process was slightly slower than that in deionized water environment,the final removal efficiency still reached 94.75%.The EEMs image also confirmed an obvious downward trend of BPA concentration,which shows that the supported membrane AMSM has the potential to deal with the problem of real water pollution.