Study On The Activation Of Periodate By Cuprous Oxide To Degrade Organic Pollutants In Water

Refractory organic wastewater has adverse effects on aquatic ecosystem and human health,but traditional biological methods are difficult to treat the organic pollutants in it.In order to effectively remove organic pollutants in water and provide theoretical reference,in this paper,heterogeneous catalyst cuprous oxide（Cu₂O）was introduced into periodate（PI）activation system for the first time to establish an organic degradation system in water,explore the influencing factors and reaction mechanism,and evaluate the catalytic stability.On the basis of that,thermal energy is introduced to enhance the treatment efficiency of Cu₂O/PI system,and the influencing factors and degradation mechanism are explored.Firstly,the factors influencing the catalytic activation of PI by Cu₂O were studied,and the degradation efficiency of methylene blue（MB）by Cu₂O/PI system was evaluated by initial concentration of PI,dosage of Cu₂O,initial p H and inorganic anions.Under the conditions of PI initial concentration 0.5 m M,Cu₂O dosage 1.0 g/L and system temperature25±1℃,the degradation rate of MB reached 96.3%.When p H was neutral and acidic,the removal rate of MB by Cu₂O/PI system increasesd,but it was inhibited under alkaline condition.The high concentration of SO₄^2-and the high concentration of NO₃^-（5.0 m M and 10.0 m M）slightly inhibited the removal effect of MB in Cu₂O/PI system,while the high content of Cl^-significantly inhibited the removal effect.CO₃^2-had significant inhibitory effect,and the effect increased with increasing concentration.The active species in Cu₂O/PI system were hydroxyl radical（·OH）,superoxide radical(O₂^·-)and singlet oxygen（¹O₂）.Main active species for singlet oxygen,the super oxygen free radical also played an important role.XPS spectra showed that the valence state of Cu in Cu₂O/PI system changed,and some of them changed into high-valence State Cu（Ⅱ）.Combined with the free radical scavenging experiments,it was found that the redox of Cu played an important role in the production of ¹O₂.Dissolved oxygen promoted MB degradation.In addition,the catalyst had strong stability,and the degradation rate of MB did not decrease significantly after 5 cycles of reaction.XRD and XPS characterization showed that the catalyst structure was basically unchanged before and after reaction.Then,the degradation efficiency of the organic pollutant ofloxacin（OF）was evaluated by the initial concentration of PI,dosage of Cu₂O,initial p H,reaction temperature and co-existing inorganic anions in the thermal/Cu₂O/PI system.The results showed that the degradation rate of OF by thermal/Cu₂O/PI reaction system increases with the increase of initial concentration of PI or Cu₂O dosage.With the decrease of p H,the removal rate of OF increased.The thermal activation energy could effectively enhance the degradation performance of Cu₂O/PI system.After 40 min,the removal rate of OF by thermo/Cu₂O/PI system reached 89.3%,which increase by 44.5%.The degradation of OF by thermo/Cu₂O/PI system increased with the increase of reaction temperature.NO₃^-slightly inhibited the reaction rate in the early stage of thermo/Cu₂O/PI system,the high content of Cl^-significantly inhibited the degradation of OF,and the effect of CO₃^2-significantly inhibited,and increased with the increase of concentration.The active species in thermo/Cu₂O/PI system were·OH,O₂^·-and ¹O₂.Main active species for singlet oxygen,the super oxygen free radical also played an important role.XPS spectra showed that the valence state of Cu element in Cu₂O changed after the reaction of thermal/Cu₂O/PI system,and some of them changed into high-valence State Cu（Ⅱ）.Combined with the free radical scavenging experiments,it was found that the redox of Cu played an important role in the production of ¹O₂.Dissolved oxygen promoted the degradation of thermal/Cu₂O/PI system.In addition,the catalyst had strong stability,and the degradation rate of OF did not significantly decreased after 5 cycles of reaction.XRD and XPS characterization showed that the structure of the catalyst was basically unchanged before and after reaction.