Fundamental Study On Reactive Oxygen Species Generation Of Alkaline Medium With Microbubbles' Intensification

Currently,advanced oxidation processes?AOPs?are usually applied to decompose refractory compounds.However,the mainstream advanced oxidation technologies are more studied on neutral or acidic solutions and less on strong alkali solution.Intensified by physical or chemical means,AOPs generate reactive oxygen species?ROS?with high oxidative activity,such as·OH,O₂^2-and O₂^-.Microbubbles'collapsing is one of the most efficient methods of ROS generation but related research lack systematic analysis,especially in strong alkaline media.In order to obtain formation mechanism and conversion principles of ROS,different ROS quantitative methods aimed at alkaline solutions were established.Microbubbles'enhancing effects into ROS generation and its quantitative regulation patterns under different conditions were studied.The following innovative results were obtained:?1?Methods of ROS quantitative detection in alkaline media were established and ROS was quantified for the first time by using fluorescent probe and potassium hexacynoferrate???.The appropriate probe was screened out and the optimum probe addition and reaction time were determined.In addition,potassium hexacynoferrate???was innovatively used to quantify ROS concentration of alkaline solution and its decomposition rate was identified under high temperature and concentrated alkaline solutions.Compared to experimental data by two methods,the applicable temperature and alkaline concentration scope of each method were determined.?2?The conversion principles of ROS in KOH and NaOH solutions exerted by size-controllable microbubbles were obtained.ROS generation principles under different microbubble size,temperature and alkaline concentration were studied using the probe and potassium hexacynoferrate???methods.It proved that microbubbles enhance ROS formation considerably.And the optimum microbubble size,temperature and alkaline concentration value of KOH and NaOH solution were determined and analyzed.?3?The oxidative activity of ROS was verified by degradation of disodium ethylenediamine tetraacetate?EDTANa₂?of NaOH solution intensified by microbubbles.Compared with H₂O₂ concentration measured by potassium hexacynoferrate???method and EDTANa₂ degradation respectively at different temperatures and NaOH concentrations,the values were both in the range of milimole,which verified the accuracy of ROS concentration within a certain scope by using potassium hexacynoferrate???method.