Porous Alkali-Activated Manganese and Copper Composites for Wastewater Treatment. Catalytic Wet Air Oxidation of Bisphenol A and Pharmaceutical Residues

Based on the published research, municipal and industrial wastewater contains highly toxic and non-biodegradable compounds, such as plastic manufacturing raw materials and pharmaceutical residues. This also poses challenges for the wastewater treatment and especially for its sensitive biological process and bacteria. To secure the distribution and use of clean water now and in the future, new and even more efficient wastewater treatment techniques are needed. Such are the new advanced oxidation processes, where e.g., active metal catalysts, such as platinum and ruthenium or cheaper manganese and copper, enhance the oxidation of toxic and non-biodegradable compounds into less harmful compounds, even to carbon dioxide and water.
In this thesis, ecological porous supports for manganese and copper catalysts were prepared from inexpensive raw materials. These composites were prepared from a clay-based raw materials by a simple and inexpensive alkali-activation process. The functionality of the metal composites was investigated in an efficient and ecological oxidation process, catalytic wet air oxidation (CWAO), with toxic bisphenol A (BPA) model solution, and with pharmaceutical wastewater containing several different toxic organic compounds. In the reactions of BPA in CWAO with copper composite, BPA decomposed by 98 percent and with manganese composite by 60 percent, respectively. In the reactions of pharmaceutical wastewater in CWAO with manganese composite the toxic organic compounds decomposed by 54 percent and with copper composite by 43 percent, respectively. In addition, the biodegradability of the treated pharmaceutical wastewater was determined, i.e., how the non-biodegradable compounds had been converted into a biodegradable form. The biodegradability of toxic organic compounds increased by 65 percent with manganese composite and 75 percent with copper composite, respectively.
The results obtained in this work showed that a simple manufacturing method could produce ecological and inexpensive metal composites that were catalytically highly active and chemically and mechanically stable. The significantly increased biodegradability of organic compounds achieved in the oxidation of pharmaceutical wastewater with metal composites was a very promising and encouraging result for further research and development of manganese and copper composites.