Immobilization of arsenic in soils by stabilized nanoscale zero-valent iron, iron sulfide (FeS), and magnetite (Fe3O4) particles

Abstract

Arsenic is a widespread contaminant in soils and groundwater. While various iron-based materials have been studied for immobilizing arsenic in contaminated soils, the feasibility of stabilized iron-based nanoparticles has not been reported. This study investigates the effectiveness of using three types of starch-stabilized iron-based nanoparticles, including zero-valent iron (ZVI), iron sulfide (FeS), and magnetite (Fe 3 O 4 ), for immobilization of arsenic in two representative As-contaminated soils (an orchard soil and a fire range soil). To test the effect of the nanoparticles on the arsenic leachability, As-contaminated soils were amended with the nanoparticles at various Fe/As molar ratios (5 : 1-100 : 1) and contact time (3 and 7 d). After three days' treatments of a field-contaminated sandy soil, the PBET-based bioaccessibility of As decreased from an initial (71.3±3.1)% (mean±SD) to (30.9±3.2)% with ZVI, (37.6±1.2)% with FeS, and (29.8± 3.1)% with Fe 3 O 4 at an Fe/As molar ratio of 100 : 1. The TCLP-based leachability of arsenic in a spiked fire range soil decreased from an initial (0.51±0.11)% to (0.24±0.03)%, (0.27±0.04)% and (0.17±0.04)% by ZVI, FeS, and Fe 3 O 4 nanoparticles, respectively. The Fe 3 O 4 nanoparticles appeared to be more effective (5% or more) than other nanoparticles for immobilizing arsenic. When the two soils were compared, the treatment is more effective on the orchard soil that has a lower iron content and higher initial leachability than on the range soil that already has a high iron content. These results suggest that these innocuous iron-based nanoparticles may serve as effective media for immobilization of As in iron-deficient soils, sediments or solid wastes. particles. Chinese Sci Bull, 2010Bull, , 55: 365−372, doi: 10.1007 Various natural sources (e.g., natural geochemical reactions) and anthropogenic activities (e.g., mining, discharges of industrial wastes, military activities, and application of agricultural pesticides) can lead to arsenic (As) contamination of soils and groundwater. Arsenic is ranked the second most common inorganic pollutant in the U.S. superfund sites [1]. Arsenic-contaminated soils, sediments and waste slurry are major sources of arsenic in food and water. To mitigate the toxic effect on human health, the maximum contaminant level (MCL) for arsenic in the U.S. drinking water was lowered from the previous 50 ppb to 10 ppb, effective in January 2006. Arsenic is a redox active element, with As(V) or As (III) being the two most common stable oxidation states in soils [2]. In general, As(III) is more toxic than As(V), and inorganic arsenic is more toxic than organic arsenic [3], and arsenic in soils is less bioavailable and less bioaccessible than As in water due to soil adsorption effect [4].Arsenate can strongly interact with soils, especially, iron (hydr)oxides. Adsorption of arsenate by iron (hydr)oxides 366 ZHANG MeiYi, et al. Chinese Sci Bull February (2010) Vol.55 No.4-5 have been widely studied [5−13]. These studies have focused on the adsor...

XAFS study of starch-stabilized magnetite nanoparticles and surface speciation of arsenate

“…Among various stabilizers tested, starch has been recognized as an effective, low-cost and environmentally benign material. Starch-stabilized magnetite nanoparticles (SMNP) have displayed much improved physical stability, soil mobility, and sorption capacity for arsenic compared with non-stabilized bare magnetite particles (He and Zhao, 2005;Zhang et al, 2010;An et al, 2011).…”

Application of stabilized zero valent iron nanoparticles for immobilization of lead in three contrasting spiked soils

“…In last decade, ZVINs have been investigated as a new tool for the treatment of contaminated water and soil [8][9][10][11][12][13]. The ZVINs applications as a solution for some problems caused by pollutants are being used successfully for treating the various heavy metal ions including Cr 6?…”

“…It has been suggested that the use of ZVINs to remediate As-polluted soils is a promising in situ strategy [30]. Zhang et al [13] reported a high reduction of As bioavailability in soils after treatment with ZVINs. Alidokht et al [31] also found good results for Cr immobilization in a spiked soil following the starch-stabilized ZVINs application.…”

A brief review of graphene-based material synthesis and its application in environmental pollution management

“…Graphene is a two-dimensional nanomaterial that has between one and ten layers of sp 2 -hybridized carbon atoms arranged in six-membered rings. It has many unique properties, including interesting transport phenomena, and high Young's modulus (approximately 1100 GPa) [ Importantly, it could be used in pollutant removal in environmental remediation, which has attracted increasing research in recent few years [5][6][7][8][9][10] and is the focus of this review. Aggregation of graphene layers determines the practical specific surface area, and modification of pristine graphene with other compounds will decrease the aggregation and increase the effective surface area.…”