Effects of Sulfidation, Magnetization, and Oxygenation on Azo Dye Reduction by Zerovalent Iron.
Applications of zerovalent iron (ZVI) for water treatment under aerobic conditions include sequestration of metals (e.g., in acid mine drainage) and decolorization of dyes (in wastewaters from textile manufacturing). The processes responsible for contaminant removal can be a complex mixture of reduction, oxidation, sorption, and coprecipitation processes, which are further complicated by the dynamics of oxygen intrusion, mixing, and oxide precipitation. To better understand such systems, the removal of an azo dye (Orange I) by micron-sized granular ZVI at neutral pH was studied in open (aerobic) stirred batch reactors, by measuring the kinetics of Orange I decolorization and changes in "geochemical" properties (DO, Fe(II), and Eh), with and without two treatments that might improve the long-term performance of this system: sulfidation by pretreatment with sulfide and magnetization by application of a weak magnetic field (WMF). The results show that the changes in solution chemistry are coupled to the dynamics of oxygen intrusion, which was modeled as analogous to dissolved oxygen sag curves. Both sulfidation and magnetization increased Orange I removal rates 2.4-71.8-fold, but there was little synergistic benefit to applying both enhancements together. Respike experiments showed that the enhancement from magnetization carries over from magnetization to sulfidation, but not the reverse.
School of Environmental Science and Engineering, Shandong University , Jinan, Shandong 250100, P.R. China.
Chunhua
C
Xu
School of Environmental Science and Engineering, Shandong University , Jinan, Shandong 250100, P.R. China.
Bingliang
B
Zhang
School of Environmental Science and Engineering, Shandong University , Jinan, Shandong 250100, P.R. China.
Yahao
Y
Wang
School of Environmental Science and Engineering, Shandong University , Jinan, Shandong 250100, P.R. China.
Qianqian
Q
Shao
School of Environmental Science and Engineering, Shandong University , Jinan, Shandong 250100, P.R. China.
Weizhi
W
Zhou
Office of Superfund Remediation and Technology Innovation, U.S. Environmental Protection Agency , Arlington, Virginia 22202, United States.
Dimin
D
Fan
School of Sciences, Saint Francis University , 117 Evergreen Drive, Loretto, Pennsylvania 15940, United States.
Joel Z
JZ
Bandstra
School of Environment and Energy South China, University of Technology, Guangzhou , Guangdong 510006, P.R. China.
Zhenqing
Z
Shi
Institute of Environmental Health, Oregon Health & Science University , 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States.
Paul G
PG
Tratnyek
D001391:Azo Compounds / Q000737:chemistry; D004396:Coloring Agents; D007501:Iron / Q000737:chemistry*; D062065:Wastewater; D018508:Water Purification
D001391:Azo Compounds; D004396:Coloring Agents; D007501:Iron; D062065:Wastewater