title: Excellent performance of cobalt-impregnated activated carbon in peroxymonosulfate activation for acid orange 7 oxidation.
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.
authors.affiliation: School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215001, People's Republic of China.|Brook Byers Institute for Sustainable Systems and the School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
authors.forename: Tianyin
authors.initials: T
authors.lastname: Huang
authors.affiliation: School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215001, People's Republic of China. chenjiabincn@163.com.
authors.forename: Jiabin
authors.initials: J
authors.lastname: Chen
authors.affiliation: School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215001, People's Republic of China.
authors.forename: Zhongming
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Brook Byers Institute for Sustainable Systems and the School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Guo
authors.affiliation: 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.
authors.forename: John C
authors.initials: JC
authors.lastname: Crittenden
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D001557:Benzenesulfonates / Q000737:chemistry; D003035:Cobalt; D010084:Oxidation-Reduction; D010545:Peroxides
chemical_list: D001391:Azo Compounds; D001557:Benzenesulfonates; D010545:Peroxides; C038288:peroxymonosulfate; D003035:Cobalt; C014722:2-naphthol orange
keywords: Activated carbon; Chloride; Cobalt; Orange acid 7; Peroxymonosulfate