Application of Solar Photocatalysis and Solar Photo-Fenton Processes for the Removal of Some Critical Charged Pollutants: Mineralization Trends and Formation of Reaction Intermediates

摘要

The present study investigated the efficiency of the titanium dioxide (TiO_2 )-assisted solar photocatalytic degradation (SPCD) process and the solar photo-Fenton degradation (SPFD) process for the removal of some crit- ical charged aqueous-phase pollutants under solar radiation conditions in Dhahran. The findings revealed that phenol and its reaction intermediate compounds can be success- fully removed via the SPCD process at acidic pH values via a one sun-type re-circulating plug flow-type reactor. A similar trend was noted for the solar photo-Fenton process, which also indicated high phenol degradation at pH of 4 and 6; however, at pH 10, the overall total organic carbon removal was low because of increased Fe-species precipita- tion and reduced ·OH radical formation. The SPCD process showed greater ammonia removal efficiency than the SPFD process. Based on the successful application of the SPCD process,wefurtherinvestigatedthedegradationofothercrit- ical charged cationic and anionic pollutants using the SPCD process.Tetramethylammonium(TMA)SPCD-baseddegra- dation resulted in near-complete TMA degradation within a reactiontimeof4h.Furthermore,theintermediatesproduced by TMA solar-energized degradation showed a stepwise de- methylationofTMAintotrimethylammonium,dimethylam- monium,andmethylammonium, followedbymineralization to NH_4~+/NH_3 and NO_3~-. In general, the results of the present work confirmed successful application of the SPCD process for the removal of several important pollutants.