Environmentální aspekty oxidace siřičitanů na sírany v průmyslových aplikacích

Abstract

This thesis focuses on the oxidation of sulfites to sulfates in industrial applications, specifically in the sulfite pulp production process. Sulfites in wastewater pose a risk and must be oxidized to more stable sulfates using an oxidation flow reactor that processes excess cooking liqour (high sulfite content). The theoretical part of the thesis summarizes the problem of waste sulfite occurrence, sulfite oxidation, and the influence of key factors such as pH and catalysis, and also includes a description of chemical reactors. The practical part was developed in cooperation with the Biocel Paskov plant and presents a series of experiments. The material balance showed that the reactor operates with high initial concentrations of sulfites (average 52,620,7 mg∙l-1), requiring an removal efficiency of over 99,43 %. It was observed that the dosage of soda solution (pH adjustment) and air supply have the greatest influence on oxidation. The study of the influence of pH confirmed the suitability of a slightly acidic environment for oxidation. Homogeneous catalysis was investigated as a possible way to optimize the processes in the reactor. These experiments showed that cobalt and iron ions can be effective, but it is important to use the catalyst in the correct concentration (0,005 to 0,008 mol∙l-1). High concentrations of the catalyst impair the reaction. Design calculations for the introduction of continuous homogeneous catalysis indicated high consumption of catalytic salts and and savings in soda solution to a lesser extent. Overall, the work provides valuable insights into reactor operation, the influence of key parameters, and possible optimization.