Degradation Of Flotation Reagents-butyl Xanthate By O₃,O₃/H₂O₂ And UV/O₃ Methods

In this thesis,O3,O3/H2O2 and UV/O3 system were introduced for flotation reagents-butyl xanthate.The rate constant for the potassium xanthate with ozone was determined for the first time. Two different kinetic models were used for the determination of rate constant for the direct reactions between ozone and potassium n-butyl xanthate:(1)the log-reduction of ozone with potassium n-butyl xanthate in excess, (2) the competition kinetic model. Then the influences of initial pH value, gas flow, initial concentration butyl xanthate and hydroxyl radicals scavenger on pollutant degradation were investigated. The degradation rate of butyl xanthate increases as the pH value and ozone concentration increases while descends as its initial concentration increases. The removal efficiency of butyl xanthate declined along with the increasing of the hydroxyl free radical inhibitor. Meanwhile, changes in COD,TOC and UV254,pH and conductivity were also discussed. The results show that ozonation could not reduce COD and TOC observably and pH value of the solution reduced significantly. The butyl xanthate decay followed a pseudo first-order reaction. Results of GC-MS analysis showed that the main degradation products and oxidation intermediates were alcohol and carbonyl compounds.The degradation of butyl xanthate in water solution has been studied using O3/H2O2.The effect of H2O2/O3 molar ratios, initial pH value, initial concentration butyl xanthate, temperatures and scavenger of hydroxyl radicals were investigated. The degradation rate of butyl xanthate increases as the hydrogen peroxide concentration increases. The removal efficiency was high when pH was the 7-9 and temperature was 293-303K by O3/H2O2 system. The removal efficiency of butyl xanthate declined along with the increasing of the hydroxyl free radical inhibitor. The experimental result also demonstrated that with the same dosage of applied ozone and hydrogen peroxide, the multiple steps addition of ozone and hydrogen peroxide showed much higher removal efficiency than that obtained by adding hydrogen peroxide within one step before the start of the experiment. The butyl xanthate decay followed a pseudo first-order reaction. Results of GC-MS analysis showed that the main degradation products and oxidation intermediates were carbonyl compounds.The wastewater containing butyl xanthate was treated by UV/O3, and the effect of pH value and initial concentration was discussed. The experimental results showed that when initial concentration was 100mg/L, pH value was 11.36 and ozone concentration was 7.32 mg/L, the removal efficiency could reach 99% within 10 min. The degradation of butyl xanthate by UV/O3 satisfied the rule of pseudo-first order reaction kinetics. The removal rate of COD and TOC were 33.9% and 14.5%. The results suggest that UV/O3 could not generalize butyl xanthate completely, and a series of intermediate products were produced. Results of GC-MS analysis showed that the main degradation products and oxidation intermediates were alcohol and carbonyl compounds.