Environmental application of millimetre-scale sponge iron (s-Fe(0)) particles (III): The effect of surface silver.
To enhance the dechlorination reactivity of millimetric sponge iron (s-Fe(0)), a facile one-pot method was used to decorate s-Fe(0) with Ag(+) ions under ambient conditions. The results recorded by X-ray diffraction patterns, X-ray photoelectron spectra and high-resolution transmission electron microscopy demonstrated that the growth of Ag(0) was dominated primarily by (111) plane with a mean length of ∼20 nm. The roles of Ag(0) loading, catalyst dosage, particle size, initial pH and contaminant concentration were assessed during the removal of pentachlorophenol (PCP). Catalyst recyclability was also studied. The results revealed that 3-5mm s-Fe(0) particles with 5 wt% Ag(0) loading exhibited the best performance with a dose of 3.0 g per 60 mL PCP solution. In addition, the dechlorination of PCP followed two-step, pseudo-first-order reaction kinetics, and Ag(0)-s-Fe(0) was advantageous compared with bimetals of nanoscale zero-valent iron, iron power and iron flakes. The dechlorination mechanism of PCP over Ag(0)-s-Fe(0) was attributed to the surface Ag(0) decoration, which catalyzed the formation of reactive hydrogen atoms for indirect reaction, and the direct electron transfer via Fe-Ag(0) galvanic cells for direct reaction. This suggests that Ag-based bimetals of s-Fe(0) have great potential in the pretreatment of organic halogen compounds in aqueous solution.
South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655, PR China; South China Subcenter of State Environmental Dioxin Monitoring Center, Guangzhou 510655, PR China; Innovative Laboratory for Environmental Functional Materials and Environmental Applications of Microwave Irradiation, Guangzhou 510655, PR China.
Yongming
Y
Ju
South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655, PR China. Electronic address: yuyunjiang@scies.org.
Yunjiang
Y
Yu
South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655, PR China; Innovative Laboratory for Environmental Functional Materials and Environmental Applications of Microwave Irradiation, Guangzhou 510655, PR China.
Xiaoyan
X
Wang
South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655, PR China.
Sukun
S
Zhang
South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655, PR China; Innovative Laboratory for Environmental Functional Materials and Environmental Applications of Microwave Irradiation, Guangzhou 510655, PR China.
Runlong
R
Liu
South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655, PR China.
Jianping
J
Fu
South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655, PR China.
Jinglei
J
Han
South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655, PR China.
Jiande
J
Fang
Environmental Engineering and Science Program, Department of Biomedical, Chemical and Environmental Engineering (DBCEE), University of Cincinnati, Cincinnati, OH 45221-0012, USA. Electronic address: dionysios.d.dionysiou@uc.edu.
Dionysios D
DD
Dionysiou
Mechanism; Millimetric zero valent iron (mmZVI); Organic halogen compounds; Pentachlorophenol (PCP); Silver-loaded sponge iron