Catalytic Ozonation Of Dyeing Sludge With Six Heterogeneous Catalysts

With the development of dyeing industries, the production of the dyeing sludge vastly increased. The problem that the treatment of dyeing sludge with high moisture is different to treatment becomes a roadblock to the progress of the dyeing industries, thereby causing a widely urgent concerning. In order to try to solve this problem, this paper adopts a series of catalysts coupled with ozone to treat with the dyeing sludge. Six catalysts (AC/M (M=Cu, Fe, Zn, Ni, Mn, Ce)) were made of six transition metal (Cu, Fe, Zn, Ni, Mn and Ce) compounds separately supported on activated carbon (AC), which were prepared by impregnation method, were assessed as ozonation catalysts for the removal of aqueous phenol solution and dyeing sludge at room temperature. Six AC/M catalysts were characterized by Boehm titrations, XRD, SEM, BET and microcomputer differential thermal balance analyses. The presence of either AC/M catalysts considerably improved their degradation in the ozonation of phenol and dyeing sludge.In order to accelerate the speed of COD analysis, we replacing sulphoacid and silver sulfate solution by combining acid of sulphoacid with phosphoric acid as catalysts in the reflux process, the analysis is quicker than the standard method and the time is shortened from120min to20min. Compared to the standard method, the optimization method also has a high degree of precision and accuracy.The comparison of the phenol decomposition rates was carried out under the different conditions of employing following oxidants:a) ozone (O3) only, b) AC/M catalysts only, and c) AC/M catalysts with O3, catalystic effect of phenol decreased in the order of c)>b)>a). Decomposition of phenol decreased in the order of AC/Fe> AC/Zn> AC/Ni> AC/Ce> AC/Cu> AC/Mn. With the increasing of pH value of phenol solution, the greater degradation could be found. The results show that the ozonation of phenol catalyzed by AC/M are strongly inhibited in the presence of TBA (tert-Butanol), suggesting that the uncharged surface hydroxyl groups on the catalysts in water can induce aqueous ozone decomposition to generate hydroxyl radicals. After25min of catalytic ozonation of dyeing sludge, decomposition of dyeing sludge filtrate’s COD values was decreased in the order of AC/Fe> AC/Zn> AC/Ce> AC/Ni> AC/Cu> AC/Mn. When the pseudo-second-order rate constant values were plotted against various phenol concentrations, a good linearity was observed, suggesting that the ozonation reaction is of second-order with respect to phenol concentration. All the tested six catalysts were found to be effective ozonation catalysts. Among the catalysts, AC/Fe enabled the highest mineralization degree. Decomposition of the organic matter of dyeing sludge decreased in the order of AC/Fe>AC/Zn> AC/Ce≈AC/Ni> AC/Cu> AC/Mn, and the organic matter of dyeing sludge could be reduced by8.17%by applying AC/Fe catalyst with ozone. Reduction of moisture content of dyeing sludge in the order of AC/Fe> AC/Zn> AC/Ce> AC/Ni≈AC/Cu> AC/Mn. With respect to the non-processed sludge, AC/Fe with ozone could reduce36.9%volume of dyeing sludge.