Remediation of polybrominated diphenyl ethers in soil using Ni/Fe bimetallic nanoparticles: Influencing factors, kinetics and mechanism
Introduction
Polybrominated diphenyl ethers (PBDEs) have been widely used as brominated flame retardants in various industrial products, especially in electronic and telecommunication equipment (Mrof et al., 2005). It is estimated that 67,000 metric tons/year of PBDEs may have been released into the environment via electronic waste generation alone (Kwan et al., 2013). These compounds are highly recalcitrant to different types of degradation (Kwan et al., 2013). As a result, PBDEs are ubiquitously detected in the environment. Due to their high hydrophobicity and high octanol/water partition coefficients (Kow), PBDEs tend to accumulate in soil, particularly in e-waste disposal and recycling sites. As pointed by Wang et al. (2011), the total concentration of PBDEs (ΣPBDEs) in soil ranged from 4.8 to 533 ng/g dry wt near a typical e-waste recycling site in South China.
PBDEs pose various adverse effects, on human and environmental health, particularly when they accumulate in living organisms, including teratogenicity and carcinogenicity, etc. (Kierkegaard et al., 1999). Therefore, there has been an urgent need for developing effective remediation technologies to eliminate PBDEs in contaminated soils.
The reported methods for remediation of PBDEs contaminated soil include biodegradation (Vonderheride et al., 2006), phytoremediation (Kevin et al., 2006), electrokinetic remediation (Wu et al., 2012) and electric-magnetic methods (Wu et al., 2013a, Wu et al., 2013b). Recently, various nanomaterials, especially those based on nanoscale zero-valent iron (nZVI) have offered a new approach for developing the next generation of environmental remediation technologies. Numerous publications have demonstrated that nanoscale zero-valent iron (nZVI) can be effectively used for soil in-situ remediation of several contaminant groups, such as chlorinated organic compounds, toxic metals and inorganic compounds (Li et al., 2007). However, there is a lack of investigations of its application for PBDEs contaminated soil remediation.
However, previous work has shown that nZVI was able to effectively degrade PBDEs in the aqueous solution (Li et al., 2007, Fang et al., 2011a). For instance, Shih and Tai (2010) reported that nZVI was able to degrade 90% BDE209 in water within 40 min at various initial pHs. The Fang group (Fang et al., 2011b) showed that nZVI prepared from steel pickling liquor degraded 95% of tetrahydrofuran (THF) in water within 24 h at 4 g/L.
While over the years of research, researchers have identified several constraints with nZVI. First, due to the extremely small size and high surface energy, nZVI particles are vulnerable to aggregation via Van der Waals and magnetic attraction forces, hence diminishing their reaction effectiveness (Phenrat et al., 2007). Second, the formation of iron oxide or hydroxide on the surface of nZVI (Li et al., 2006) also decreases the electron transfer and reductive reactivity. Third, the reactivity of nZVI alone was often found insufficient for degrading recalcitrant chemicals such as halogenated chemicals. To prevent the aggregation of nanoparticles, researchers found that loading a second metal catalyst such as Ni or Pd on nZVI can greatly speed up the reaction rate (Fang et al., 2011a, Choi et al., 2008, Choi et al., 2009). Based on literature, bimetallic nanoparticles have been investigated to enhance the reactivity and mobility of nanoparticles. Thus, they have been used to employ for the remediation of Persistent Organic Pollutants (POPs) in soil. For example, Pd/Fe0 bimetallic nanoparticles show significant performance on catalytic dechlorination of polychlorinated biphenyls (PCBs) and gamma-hexachlorocyclohexane (γ-HCH) in soil (He et al., 2009, Singh et al., 2012). Recently, Fang et al. utilized Ni as a catalyst to synthesize Ni/Fe bimetallic nanoparticles, which demonstrated about 53-fold faster debromination rate for BDE209 than plain nZVI (Fang et al., 2011a). And Ni was shown to have better corrosion stability and lower cost while compared to Pd (Theron et al., 2008). However, the degradation of PBDEs in soil using the nano bimetallic Ni/Fe particles needs yet to be explored.
The objectives of this study were to: 1) investigate the degradation effectiveness of BDE209 in soil by Ni/Fe bimetallic nanoparticles, 2) test the influencing factors (pH, dosage of the nanoparticles and BDE209 initial concentration, and Ni loading), and 3) identify the reaction intermediates and products and elucidate the degradation pathways and mechanisms.
Section snippets
Chemicals and materials
Decabromodiphenyl ether (BDE209 > 98%), ferrous sulfate (FeSO4·7H2O,>99%), sodium borohydride (NaBH4 > 98%), nickel chloride (NiCl2·6H2O, > 99%), polyvinylpyrrolidone (PVP, K-30), and ethanol (EtOH, 99.7%) were purchased from Tianjin Damao Company. Acetonitrile and methanol (HPLC grade) were obtained from Tianjin Kermel Chemical Reagents Company. All chemicals were used as received without further purification. We have demonstrated the preparation and characterization of Ni/Fe bimetallic
Effect of Ni/Fe dosage
As shown in Fig. 1, the variations on removal efficiency during the initial phase of reaction showed a marked increase, and then tended to be balanced in the late phase of reaction. Finally, the reaction achieved a balance within 72 h. And BDE209 removal efficiency increased with the increasing Ni/Fe dosage. An increase of removal efficiency ranged from 21.19% to 52.86% (increasing nearly 32%) when the dosage increased from 0.01 g/g to 0.02 g/g. But it enhanced by 12% when the dosage increased
Conclusion
As mentioned above, the use of nZVI and modified-nZVI has been studied intensely for dehalogenation of halogenated organic in aqueous phase. But knowledge about the applicability of nZVI for the remediation of PBDEs contaminated soil is poorly understood. Laboratory experiments presented here involved the preparation of Ni/Fe bimetallic nanoparticles and investigation of remediation of PBDEs in soil using Ni/Fe nanoparticles. Information obtained from these experiments will lead to the
Conflict of interest
We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of the manuscript entitled, “In-situ Remediation of Polybrominated Diphenyl Ethers in Soil Using Ni/Fe Bimetallic Nanoparticles: Influencing Factors, Kinetics and
Acknowledgments
This research was supported by the Guangdong Technology Research Centre for Ecological Management and Remediation of Urban Water Systems (2012gczxA005), Science and Technology Planning Project of Guangdong Province (2012B031000015) and the Scientific Research Foundation of the Graduate School of South China Normal University (2012kyjj239).
References (42)
- et al.
Simultaneous adsorption and degradation of g-HCH by nZVI/Cu bimetallic nanoparticles with activated carbon support
Environ Pollut
(2011) - et al.
Cross-column prediction of gas-chromatographic retention of polybrominated diphenyl ethers
J Chromatogr A
(2013) - et al.
Debromination of polybrominated diphenyl ethers by Ni/Fe bimetallic nanoparticles: influencing factors, kinetics, and mechanism
J Hazard Mater
(2011) - et al.
Degradation of the polybrominated diphenyl ethers by nanoscale zero-valent metallic particles prepared from steel pickling waste liquor
Desalination
(2011) - et al.
Catalytic dechlorination of polychlorinated biphenyls in soil by palladium–iron bimetallic catalyst
J Hazard Mater
(2009) - et al.
Retention-time database of 126 polybrominated diphenyl ether congeners and two Bromkal technical mixtures on seven capillary gas chromatographic columns
J Chromatogr A
(2005) - et al.
Sedimentary PBDEs in urban areas of tropical Asian countries
Mar Pollut Bull
(2013) - et al.
Bioaccumulation and bioavailability of polybrominated diphynel ethers (PBDEs) in soil
Environ Pollut
(2010) - et al.
Nanoscale Pd/Fe bimetallic particles: catalytic effects of palladium on hydrodechlorination
Appl Catal B Environ
(2007) - et al.
Catalytic dechlorination of chlorophenols in water by palladium/iron
Water Res
(2001)
Sorption isotherms of brominated diphenyl ethers on natural soils with different organic carbon fractions
Environ Pollut
Reaction of decabrominated diphenyl ether by zerovalent iron nanoparticles
Chemosphere
Degradation of γ-HCH spiked soil using stabilized Pd/Fe0 bimetallic nanoparticles: pathways, kinetics and effect of reaction conditions
J Hazard Mater
Remediation of PCB contaminated soils using iron nano-particles
Chemosphere
Characterization of PBDEs in soils and vegetations near an e-waste recycling site in South China
Environ Pollut
Catalytic dechlorination of Aroclor 1242 by Ni/Fe bimetallic nanoparticles
J Colloid Interface Sci
Synthesis of reactive nano-Fe/Pd bimetallic system-impregnated activated carbon for the simultaneous adsorption and dechlorination of PCBs
Chem Mater
Adsorption and simultaneous dechlorination of PCBs on GAC/Fe/Pd: mechanistic aspects and reactive capping barrier concept
Environ Sci Technol
Influence of the oxidizing species on the reactivity of iron-based bimetallic reductants
Environ Sci Technol
Sorption and desorption of naphthalene by soil organic matter: importance of aromatic and pliphatic components
J Environ Qual
Fe/Ni bimetallic particles transport in columns packed with sandy clay soil
Ind Eng Chem Res
Cited by (92)
Modified nano zero-valent iron coupling microorganisms to degrade BDE-209: Degradation pathways and microbial responses
2024, Journal of Hazardous MaterialsRecent advances in bimetallic nanoscale zero-valent iron composite for water decontamination: Synthesis, modification and mechanisms
2024, Journal of Environmental ManagementDegradation on BDE209 in the soil by kaolin-supported sulfurized nano-zero-valent iron activated persulfate system: Insights mechanism and DFT calculations
2024, Journal of Environmental Chemical EngineeringSimultaneous remediation of co-contaminated soil by ball-milled zero-valent iron coupled with persulfate oxidation
2023, Journal of Environmental Management