Catalytic Ozonation Of Methylene Blue In Aqueous Solution By Cu/Ac From Brewing Yeast

Ozone has received extensive interests for its strong ability of oxidation anddecolorization. Nevertheless, low solubility and stability of ozone in water limit itspractical application. It has been demonstrated that catalytic ozonation with transitionmetal loaded catalyst can improve ozone utilization and the efficiency wastewatertreatment.In this thesis, AC and Cu/AC catalyst were prepared using brewing yeast as rawmaterial. The adsorption properties and mechanisms of AC and Cu/AC wereinvestigated. The properties of catalytic ozonation with the Cu/AC catalyst and thedegradation mechanism of pollutant were studied. The main finds of this thesis aresummarized as follows:1．Preparation and evaluation of adsorptive property for AC and transition metalloaded AC catalystThe performance of prepared AC for MB removal in various conditions usingsodium carbonate as activator in terms of adsorption-activation was determined. Theoptimum condition for preparation of AC was found as follows: carbonization for4h，at carbonization temperature of700℃and massratio of yeast and sodium carbonate of4:1. It was shown that AC and Cu/AC contains graphite structural microcrystals fromXRD, FTIR and BET characterization; carbonyl, amide, carboxyl and hydroxyl groupswere found on the surface of both AC and Cu/AC. Specific surface area, volume of poreand average pore size of AC and Cu/AC were957.7m²/g and438.47m²/g,0.81mL/gand0.32mL/g,3.83nm and2.91nm, respectively. The result of effect of solution pH,adsorption time and pollutant concentration to AC and Cu/AC adsorption for MBremoval indicated that pH had little influence on adsorption capacity of MB，equilibrium time for AC and Cu/AC were3h and2h, respectively. The adsorptionprocess followed the pseudo-first-order and pseudo-second-order kinetics; Freundlichequation matched better for the description of AC adsorption of MB. Langmuir equationand Freundlich equation both fitted isotherms of the Cu/AC adsorption of MB; Themaximum adsorption capacity of MB were407.77mg/g and121.25mg/g, respectively.The mechanism of MB removal and adsorption by AC and Cu/AC Zeta potentialand FTIR was discussed. It is determined that surface functional groups （samido,carboxyl, and hydroxy） were involved in the adsorption of MB. 2. Catalytic performance evaluation of Cu/ACFive reaction systems namely O₃, O₃/UV, O₃/UV/AC, O₃/Cu/AC andO₃/UV/Cu/AC were applied for the treatment of MB in the aquatic environment. It wasfound that TOC removal rate in O₃/UV/Cu/AC system reached68.05%which was thebest among the systems. It is obvious that Cu/AC had catalytic ozonation activity. TheO₃/UV/Cu/AC system had the highest ozone utilization with minimum OI and Cu/ACwith loading dosage of7.98%was found to be optimum for TOC removal. After reusefour times, TOC removal rate decline slightly and the dissolution of Cu estimated as1.4%¹5.6%.3. Kinetics of catalytic ozonation of Cu/ACMB degradation process in the O₃/UV/Cu/AC system with three kinetics has beenstudied. It was found that both the First and Second Kinetic Models were applicatedwell to the process of MB degradation using Cu/AC; Langmuir Hinshelwood reactionkinetics equation fitting result revealed that adsorption rate of pollutant on the catalystsurface controlled catalytic ozonation reaction; With Langmuir Isothermal AdsorptionModel coupling reaction kinetics model. It was built Langmuir–1st order andLangmuir–2nd order models to fit result. It indicated that Langmuir–1st order model fitthe data better.4. Factor influencing the Cu/AC catalytic ozonation for MB removalThe effect of solution pH value, salt concentration, dosage of Cu/AC, MB initialconcentration were studied for MB degradation in the O₃/UV/Cu/AC system. It is foundthat pH value had little influence in the system. The increase of salt concentrationdecreased the rate of catalytic ozonation. With an increase of MB initial concentration,the TOC final removal rate increased gradually, and the dosage of Cu/AC was found tobe1.6g/L.5. Mechanism of Cu/AC catalytic ozonation for MB removalThe effect of hydroxyl radical masking agent tert-butyl alcohol to MB degradationhas been investigated. It was found that the result revealed that tert-butyl alcoholshowed inhibition of Cu/AC, and it was observed that a large number of hydroxylgroups were produced on the surface after catalytic ozonation reaction. MB eventuallydegraded into small molecules of esters and acids.