Food Azo-Dyes Removal from Water by Heterogeneous Photo-Fenton with LaFeO3 Supported on Honeycomb Corundum Monoliths
JOURNAL OF ENVIRONMENTAL ENGINEERING(2015)
摘要
Heterogeneous photo-Fenton process with structured catalyst was investigated in the removal of two typical food azo dyes, red allura (RED) and tartrazine (TRZ). The influence of LaFeO3 loading (with and without Pt) on corundum honeycombs monolithic support was evaluated in the discoloration and mineralization of the target azo dyes. The results for discoloration were reported for different experimental conditions: UV, UV + H2O2, UV+ H2O2 + structured catalysts. In the case of UValone the discoloration occurs very slowly and not completely (approximately 36 and 20% in 120 min of irradiation for RED and TRZ, respectively); but the process efficiency has been enhanced in the presence of H2O2 (approximately 77 and 80% in 5 min of irradiation for RED and TRZ, respectively). The best efficiency in RED dye discoloration and mineralization by heterogeneous photo-Fenton process was observed for a LaFeO3 loading equal to 4.5% by weight (complete discoloration and 95% of TOC removal in 60 min of irradiation time), whereas for TRZ dye the optimal LaFeO3 loading was lower (2.2% by weight) (total discoloration and TOC removal in 60 min of irradiation time). Pt loading of 0.1 wt% resulted in the highest total organic carbon (TOC) removal rate during RED dye solution treatment with together the highest CO2 selectivity. For TRZ, the higher the content of Pt on the catalyst, the better is the removal of TOC. The efficiency improvement obtained in presence of Pt can be explained considering that the noble metal suppresses to some extent the charge carriers' recombination rate determining an increase of photo Fenton activity. (C) 2015 American Society of Civil Engineers.
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关键词
Heterogeneous photo-Fenton process,Food-azo dyes,Structured catalysts,Discoloration,Mineralization
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