OXIDATION OF MOLYBDENUM-CONTAINING WATER EFFLUENT OF PJSC NIZHNEKAMSKNEFTEKHIM IN SUPERCRITICAL FLUID CONDITIONS OF THE REACTION MIXTURE

In wastewater generated as a result of multi-tonnage industrial process of propylene epoxidation at PJSC Nizhnekamskneftekhim, accumulation of molybdenum in the form of various salts along with organic compounds is observed. During the reaction of propylene epoxidation, the catalytic molybdenum complex, which is obtained by chemical dissolution of metallic molybdenum in a mixture of ethyl alcohol and ethylbenzene hydroperoxide, is destroyed. This complex is used as a catalyst for the production of propylene oxide and is discharged into industrial wastewater, mainly in the form of sodium molybdate. Economic losses are aggravated by the environmental problems that have arisen, which is associated, first of all, with a lack of effective and cost-effective methods for isolating molybdenum salts from wash water. This paper presents the results of testing the oxidation process of industrial wastewater generated as a result of propylene epoxidation, which was carried out under conditions of a supercritical fluid medium. The studies were carried out both on batch-type plants, where hydrogen peroxide was used as an oxidizer, and on continuous-type plants with air, at temperatures from 673 to 723 K and pressures from 22 to 40 MPa with induction heating. Regularities were revealed, showing how the efficiency of wastewater oxidation depends on the thermodynamic parameters of the reaction and the physicochemical characteristics of the oxidizer. In addition, the elemental composition of the solid residue was determined, which opens up new prospects for further research and practical application of the data obtained. Regularities were determined, reflecting changes in the efficiency of water runoff oxidation depending on the process conditions and the physicochemical characteristics of the oxidizer used. The presence of molybdenum, which is a target product for further extraction, was recorded in the samples of the inorganic residue.