Photoinduced redox reactions between colloidal manganese dioxide and some organic compounds of environmental importance |
| |
Authors: | Ottó Horváth Gergő Z Bakota Judit Marosfi Zoltán Zsilák |
| |
Institution: | (1) Department of General and Inorganic Chemistry, University of Pannonia, 8201 Veszprém, P.O. Box 158, Hungary |
| |
Abstract: | Numerous organic compounds of environmental importance, i.e., phenol, citric, tartaric, and oxalic acids, proved to promote
or accelerate reductive dissolution of colloidal manganese dioxide upon irradiation. This is accounted for the formation of
surface-located charge-transfer complexes between the MnO2 particulates and the organic electron donors. From the dependences of the rate of the photoassisted and thermal dissolution
on the concentration of the organic compounds, the equilibrium constants for the formation of these complexes have been determined
in the case of phenol, resorcinol, citrate, and tartaric acid. The quantum yields for these photoinduced reactions (at λ
ir = 365 nm), however, do not show any correlation with the values of the corresponding equilibrium constants, although adsorption
is prerequisite for the efficient reductive dissolution of MnO2. The changes in pH markedly affect the rate of this process, indicating that protonation of both the electron donors and
the surface of the MnO2 particulates may play significant roles in these systems. The results of experiments carried out in manganese dioxide excess
suggest that total mineralization of organic electron donors is strongly hindered by the disadvantageous adsorption properties
of the primary redox products.
Dedicated to Professor Janos H. Fendler on the occasion of his 70th birthday. |
| |
Keywords: | Photoredox Manganese dioxide Dissolution Organic compounds Surface complex |
本文献已被 SpringerLink 等数据库收录! |
|