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Environ Sci Pollut Res Int. 2017 Apr;24(10):9651-9661. doi: 10.1007/s11356-017-8648-7. Epub 2017 Mar 1.

Excellent performance of cobalt-impregnated activated carbon in peroxymonosulfate activation for acid orange 7 oxidation.

Author information

1
School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215001, People's Republic of China.
2
Brook Byers Institute for Sustainable Systems and the School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
3
School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215001, People's Republic of China. chenjiabincn@163.com.
4
Brook Byers Institute for Sustainable Systems and the School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA. john.crittenden@ce.gatech.edu.

Abstract

Cobalt-impregnated activated carbon (GAC/Co) was used to produce sulfate radical (SO4·-) from peroxymonosulfate (PMS) in aqueous solution (hereafter called PMS activation). We evaluated its effectiveness by examining the degradation of orange acid 7 (AO7). GAC/Co exhibited high activity to activate PMS to degrade AO7. The degradation efficiency of AO7 increased with increasing dosage of GAC/Co or PMS and elevated temperatures. pH 8 was most favorable for the degradation of AO7 by GAC/Co-activated PMS. The radical quenching experiments indicated that the reactions most likely took place both in the bulk solution and on the surface of GAC/Co. We found that SO4·- played a dominant role in AO7 degradation. Sodium chloride (NaCl) which presents in most dye wastewater had a significant impact on AO7 degradation. Low dosages (<0.4 M) of NaCl showed a slight inhibitory effect, whereas high dosages (0.8 M) increased the reaction rate. HOCl was confirmed as the main contributor for accelerating AO7 degradation with high concentration of NaCl. In a continuous-flow reaction with an empty-bed contact time of 1.35 min, AO7 was not detected in the effluent for 0 to 18.72 L of treated influent volume (156 h) and 85% removal efficiency was still observed after 40.32 L of treated volume (336 h). Finally, the azo bond and the naphthalene structure in AO7 were destroyed and the degradation pathway was proposed.

KEYWORDS:

Activated carbon; Chloride; Cobalt; Orange acid 7; Peroxymonosulfate

PMID:
28251528
DOI:
10.1007/s11356-017-8648-7
[Indexed for MEDLINE]

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