Stabilization of heavy metals in mining soil using palygorskite loaded by nanoscale zero-valent iron

Abstract Risk associated with heavy metals in soil has been received widespread attention. In this study, a porous biochar supported nanoscale zero-valent iron (BC-nZVI) was applied to immobilize cadmium (Cd) and/or lead (Pb) in clayey soil. Experiment results indicated that the immobilization of Cd or Pb by BC-nZVI process was better than that of BC or nZVI process, and about 80 % of heavy metals immobilization was obtained in BC-nZVI process. Addition of BC-nZVI could increase soil pH and organic matter (SOM). Cd or Pb immobilization was inhibited with coexisting organic compound 2,4-dichlorophenol (2,4-DCP), but 2,4-DCP could be removed in a simultaneous manner with Cd or Pb immobilization at low concentration levels. Simultaneous immobilization of Cd and Pb was achieved in BC-nZVI process, and both Cd and Pb availability significantly decreased. Stable Cd species inculding Cd(OH)2, CdCO3 and CdO were formed, whereas stable Pb species such as PbCO3, PbO and Pb(OH)2 were produced with BC-nZVI treatment. Simultaneous immobilization mechanism of Cd and Pb in soil by BC-nZVI was thereby proposed. This study well demonstrates that BC-nZVI has been emerged as a potential technology for the remediation of multiple metals in soil.

Download Full-text

APPLICATION OF NANOSCALE ZERO-VALENT IRON FOR GROUNDWATER REMEDIATION: LABORATORY AND PILOT EXPERIMENTS

NANO ◽

10.1142/s1793292008001118 ◽

2008 ◽

Vol 03 (04) ◽

pp. 287-289 ◽

Cited By ~ 8

Author(s):

STEPANKA KLIMKOVA ◽

MIROSLAV CERNIK ◽

LENKA LACINOVA ◽

JAROSLAV NOSEK

Keyword(s):

Heavy Metals ◽

Groundwater Remediation ◽

Laboratory Experiments ◽

Permeable Reactive Barriers ◽

Zero Valent Iron ◽

Chlorinated Ethenes ◽

Soluble Form ◽

Chemical Decontamination ◽

Nanoscale Zero Valent Iron

It is known that the reductive effects of zero-valent iron ( Fe 0) and the sorptive capability of iron and its oxides can be used for both the dehalogenation of chlorinated hydrocarbons (CHC), especially of chlorinated ethenes (PCE → TCE → DCE → VC → ethene, ethane), and the removing of heavy metals from groundwater by turning them into a less-soluble form through changes of their oxidation state, or by adsorption. These consequences are being exploited in the construction of iron filling permeable reactive barriers for a longer time.1 The advantages of nanoscale zero-valent iron ( nanoFe 0) over the macroscopic one consist not only in the better reactivity implicit in their greater specific surface area but also in their mobility in rock environment.2,3 Numerous laboratory experiments, especially the batch-agitated experiments, with samples from seven various contaminated localities in Europe have been carried out with the aim to discover the measurement of the reductive effect of the nanoFe 0 on selected contaminants. It was found that the nanoFe 0 can be reliably usable as a reductive reactant for in-situ chemical decontamination of sites polluted by chlorinated ethenes (CEs), or hexa-valent chromium ( Cr VI ). The rate of reductive reaction and the optimal concentrations for the real remediation action were determined. On the basis of these laboratory experiments, the methods for pilot application of nanoFe 0 have been specified. Subsequently the pilot experiments were accomplished in surveyed localities.

Download Full-text