|Title||Application of manganese oxides under anoxic conditions to remove diclofenac from water|
|Author(s)||Liu, Wenbo; Langenhoff, Alette A.M.; Sutton, Nora B.; Rijnaarts, Huub H.M.|
|Source||Journal of Environmental Chemical Engineering 6 (2018)4. - ISSN 2213-2929 - p. 5061 - 5068.|
Sub-department of Environmental Technology
|Publication type||Refereed Article in a scientific journal|
|Keyword(s)||Anoxic abiotic pharmaceutical removal - Application - Co-solutes - Manganese oxides - MnO:diclofenac ratio - Temperature|
This study focuses on the potential of applying manganese oxides (MnO2) under anoxic conditions (absence of oxygen) to remove diclofenac (DFC). By investigating parameters that are important for application, including temperature, MnO2: DFC molar ratio, and co-solutes, the DFC removal potential is evaluated in terms of efficiency and observed initial kinetics (kobs,init). Four commonly-used kinetic models are compared in this study and the best fitting one is employed. Overall, DFC removal and kobs,init both increase upon changing temperature from 10 to 30°C and both decrease after further increasing temperature to 40°C. Increasing the MnO2: DFC molar ratio improves degradation, as this provides more reactive surface sites for DFC conversions. However, DFC removal does not further increase when increasing the MnO2:DFC from 2200:1 to 8900:1. The presence of metal ions inhibits DFC removal, possibly because the ions adsorb onto the reactive sites at the MnO2 surface and compete with DFC. Phosphate has a diverse effect on DFC degradation: low concentrations inhibit and high concentrations promote removal. The presence of humic acids significantly promotes diclofenac removal. These findings are a first step towards further developing pharmaceutical removal technology using MnO2 under anoxic conditions.