Chemiluminescence Kinetic Study On The Generation Of Hydroxyl Radicals In Fenton-like Reaction And Its Application In Sterilization And Dye Degradation Processes

Hydroxyl radical(-OH)is widely used in waste water treatment and chemiluminescence systems due to its excellent performances in oxidizing biomacromolecules,organic molecules and inorganic molecules.In conventional Fenton/Fenton-like reactions(Fe2+-H2O2,Co2+-H2O2,etc.),the reduced form of metal ions(Mred)are rapid consumed in the presence of H2O2,while the rate constant of oxidized form of metal ions(Mox)to Mred is slow.Therefore,the generation of ·OH is blocked at the initial stage of the reaction.In addition,the half-lifetime of OH is extremely short(10-9 s)in aqueous solution,partially of the OH will be annihilated before they diffuse to reactants.To overcome these demerits of the conventional systems,some modified Fenton/Fenton-like reactions(photo-Fenton process,eletro-Fenton process,water sonolysis,etc.)have been developed for the continuous generation of OH.However,these methods have to be used under special conditions,which limit their further applications.In this thesis,Tris is introduced in the conventional Co(?)-H2O2 Fenton-like system to build a new type Tris-Co(?)complex-H2O2 system.The formation of Tris-Co(?)complexes can induce a continuous generation of OH in Fenton-like reaction by decreasing the redox potential of Co(?)/Co(?).Moreover,applications of the Tris-Co(?)complex-H2O2 system in chemiluminescence,sterilization and degradation processes were investigated in this thesis,the main contribution of this paper are as follows:(1)A series of ligand-Co(?)complexes were synthesized in this section.Firstly,the stoichiometry of each complex was determined by the continuous variation method(i.e.,Job plot).Luminol-Tris-Co(?)complex-H2O2 system was find to have the longest glowing time.Moreover,Tris-Co(?)complexes were characterized by FT-IR spectra and XPS spectra.It is found that the nitrogen atoms and oxygen atoms of Tris were bound to Co(?)in the Tris-Co(?)complexes solution.Meanwhile,the main valence of cobalt ion in the Tris-Co(?)complexes is concluded to be divalent.Furthermore,the decrease of redox potential in the presence of Tris-Co(?)/Co(?)complexes improved the reduction ability of Tris-Co(?)complexes to Tris-Co(?)complexes.In addition,scavenger(SOD,t-BuOH),ESR spectra(DMPO,BMPO)and fluorescence spetra(C3C)were used to characterize the ROS in the proposed system,indicating the existence of OH and O2·-.The mechanism of continuous generating OH in the proposed system was also concluded.(2)Taken advantage of the continuous generation of OH in Tris-Co(?)complexes-H2O2 system,luminol-based chemical light system was fabricated in aqueous solution.In the chemical light system,hydrophilic carrier materials(HPMC and PVP)were adopted to supply the sustained-release of luminol and H2O2,realizing a?13 h emission with intensive and stable CL.Moreover,some CL resonance energy transfer(CRET)acceptors,such as acriflavin and eosin Y,were applied in the proposed system as to obtain the different chemical lights with tunable colors in aqueous solutions(3)High-efficiency inactivation of E.Coli by Tris-Co(?)complexes-H2O2 system in aqueous solution.The combination between Tris-Co(?)complexes and E.Coli cells could be strengthened as a result of their electrostatic interactions,facilitating the utilization of OH on the surface of E.Coli.In Tris-Co(?)complex-H2O2 system,the population of E.Coli was reduced gradually in 70 min and reduced-3.4 log at the end of the reaction.Therefore,the proposed Tris-Co(?)complex-H2O2 system exhibited great advantages in sterilization.Moreover,the morphological changes and survival rate of the E.Coli cells at different stage of the inactivation were visually observed by SEM and CLSM,indicating the high-efficiency inactivation of E.Coli in Tris-Co(?)complexes-H2O2 system.(4)High-efficiency degradation of anionic azo dyes was realized in Tris-Co(?)complex-H2O2 system.The enhanced sunset yellow(SY)degradation is based on the strong electrostatic attraction between SY and Tris-Co(?)complexes.Therefore,the continuous generated OH could react with SY in a s rt period of time.These results show that SY realized a decolorization rate of 98%and TOC removal rate of 59.4%after reacting for 50 min in Tris-Co(?)complex-H2O2 system.In addition,the universality of this system to other anionic azo dyes was validated by evaluating the high degradation efficiencies of reactive red and congo red.