Treatment Of Papermaking Wastewater By O₃Oxidation With Mn²⁺/UV As Catalyst

Ozone catalytic method has a strong effect of oxidative degradation,increasingly widespread in a variety of water treatment processes. But the technologyhave some disadvantages,such as,homogeneous catalysis,the metal is not easy to berecycled,and H₂O₂stay in water and other issues,these have become barriers tolarge-scale promotion of ozone catalytic oxidation.Non-homogeneous catalyticozone during the reaction,the catalyst is easy to overcome the above-mentionedtrouble with the nature of the separation of water,the process has a good prospect ofapplication.The paper was study expanded perlite modified and find it havecharacteristics:a large surface area and porous overall structure;high mechanicalstrength; strong adhesion to the active substance;easy to fall off, and prepared a newtype of Mn²⁺catalyst used in heterogeneous catalytic ozone oxidation treatmenttechnology to achieve low-cost,high efficiency removal of refractory organicpollutants in the wastewater.In this paper,using a continuous flow of water,the choice of papermakingwastewater biodegradable COD and chroma as a typical organic, The effects of Mn²⁺/UV catalytic O₃on the degradation of organic pollutants in energy efficiency throughexperiments has the following conclusions:Mn²⁺catalyst was made by modified expanded perlite as the carrier and itssurface load of Mn²⁺new catalyst to the system. prepared by impregnation method ofMn2+catalyst, its preparation process as: The particle size of30-60mesh modifiedexpanded perlite as a carrier. MgO;MgSO₄;MgCl₂;water and modified expandedperlite mixing ratio of150：118：16：100：10, impregnated for24hours at roomtemperature,after removing dried at this temperature. Put it into the oven at200℃for2hours, cooled to room temperature after the catalyst use.Catalyst carrier surface structure is more uniform, and has developed voidsstructure,thus increasing the adsorption and adhesion of the catalyst by scanning electron microscopy （SEM） of the catalyst characterization experiments.Continuouscatalytic reaction,the surface structure has not change much, indicating that thecatalyst surface structure is relatively stable.And content of Mn²⁺dose not changethan before,after the reaction of Mn²⁺in the catalyst it in carrier surface loadwas stability.The above experiment illustrates that it has the higher catalyst on thecatalytic ability of O₃, and can be used repeatedly.The experiment was degradation COD and chroma in papermakingwastewater,than through the different processes to determine the treatment process:Mn²⁺/UV catalyst O₃. The best conditions of the process system for the degradation ofCOD in wastewater and chroma: Amount of ozone aeration60mL/min; Aeration time40min; Catalyst dosage30g; The sewage initial concentration of523;pH7,Under thiscondition, the process of COD and chroma removal rates were73%（40min）and13%（40min）；Catalyst adsorption on the removal of COD and chroma respectively.6%（40min）and9%（40min）。Mn²⁺/UV catalyst O₃, thetechnology system of simulated wastewater COD andchroma continuous catalytic oxidation effect is good, stable operation in48hours.The catalytic performance is satisfactory, the catalyst surface of Mn²⁺loss in thereactor.Load the modified expanded perlite as a carrier of Mn²⁺in the catalystpreparation process is simple, high hardness, good wear resistance, and organic matterremoval efficiency of stable, long-term operation without further addition of otheragents, saving operating costs. Mn²⁺/UV catalytic O₃is a promising technology.