Determination Of Chlorine Dioxide And Degradation Of Dinitrophenolic Organic Wastewater In Chlorine Dioxide Catalytic Oxidation Process

Dinitrophenolic compounds, such as 2-sec-butyl-4,6-dinitrophenol (DNBP) and 2,6-dinitro-p-cresol (DNPC), have been widely used in the chemical industry as an effective inhibitor of the styrene polymerization. Industrial effluent which is contained dinitrophenolic compounds poses a severe problem of environmental pollution because of its toxicity and poor biodegradability. So it is necessary to develop new methods which could treat the dinitrophenolic wastewater more efficiently and conveniently. Chlorine dioxide is the most attractive disinfectant because the formation of trihalomethanes hardly occurs during the disinfecting process. And the use of chlorine dioxide as a disinfectant has become increased in many countries, owing to its effectiveness. Recently with the development of catalytic oxidation, chlorine dioxide has been used for the treatment of wastewater containing different kinds of organic compounds. In this paper, dinitrophenolic organic wastewater was treated in the chlorine dioxide catalytic process. And it can be divided into the following three parts:(1) The concentration of chlorine dioxide in solution was determined by using Acid Chrome Black 7 (MB 7) differential spectrophotometry. And the effect of pH values, chlorine dioxide/MB 7 molar ratios and coexistence substances on the determination was examined.(2) The catalyst was prepared by dipping method usingα-Al2O3 as carrier. Carrier pretreatment, kinds and concentration of dipping solution, dipping time, calcined temperature and time were examined in the paper. Based on the experimental results,α-Al2O3 which was selected as the catalyst was used in treatment of dinitrophenolic organic wastewater by chlorine dioxide.(3) DNBP and DNPC were treated in the chlorine dioxide oxidation process withα-Al2O3 as the catalyst. The experimental parameters such as pH values, catalyst dosage, initial concentration of DNBP/DNPC, initial concentration of chlorine dioxide and reaction time were systematically studied in the paper. The repetitive use of the catalyst was also examined. The kinetics of DNBP/DNPC degradation in aqueous solution by chlorine dioxide catalytic oxidation was analyzed.Finally, we conducted a study to determine the potential use of chlorine dioxide catalytic oxidation process for decolorization and chemical oxygen demand (COD) reduction of real nitrophenols wastewater from DNBP manufacturing. It was found that chlorine dioxide catalytic oxidation process had obvious advantages in both decolorization and chemical oxygen demand (COD) reduction compared with no catalyst process.