Wet air oxidation of a direct dye solution catalyzed by CoAlPO4-5. Performance assessment and kinetic study

Citation
Ss. Lin et al., Wet air oxidation of a direct dye solution catalyzed by CoAlPO4-5. Performance assessment and kinetic study, J ENVIR S A, 36(10), 2001, pp. 2055-2068
Citations number
35
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART A-TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING
ISSN journal
1093-4529 → ACNP
Volume
36
Issue
10
Year of publication
2001
Pages
2055 - 2068
Database
ISI
SICI code
1093-4529(2001)36:10<2055:WAOOAD>2.0.ZU;2-H
Abstract
Wet air oxidation (WAO) of a prepared direct dye solution was tested by usi ng the CoALPO(4)-5 catalyst. Addition of CoAlPO4-5 could effectively improv e rate of color removal and the activation energy of color removal could de crease from about 110 kJ/mole to about 75 kJ/mole as the catalyst loading w as increased from 0.0 g/L to 3.0 g/L. Performance of WAO on color removal w ould somewhat increase with catalyst loading at 145 degreesC whereas the ef fect of catalyst loading was not significant at 135 degreesC. With no addit ion of CoAlPO4-5, the chemical oxygen demand (COD) value was low. This was due to difficulty of exactly measuring the true COD value of dye solution i f the dye was not degraded. Via CoAlPO4-5, COD of dye solution could be eff ectively decreased. The rate of COD removal would increase with catalyst lo ading, oxygen pressure and reaction temperature. Furthermore, a maximum COD value observed, which was due to catalyzed degradation of dye molecule via CoAlPO4-5, could be characterized by a consecutive reaction scheme. Kineti c study of color removal is expressed as follows: rate = k x [dye](0.8) x W -0.5 x P " (145 degreesC) or rate = k x [dye](0.8) x W-0 x P " (135 degrees C); where k means rate constant, [] means concentration, W means catalyst l oading, P means oxygen pressure and n means uncertain number.