Arsenic Contaminated Groundwater Remediation by Entrapped 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

Application of nanoscale zero valent iron (NZVI) for groundwater remediation in Europe

Environmental Science and Pollution Research ◽

10.1007/s11356-011-0576-3 ◽

2011 ◽

Vol 19 (2) ◽

pp. 550-558 ◽

Cited By ~ 293

Author(s):

Nicole C. Mueller ◽

Jürgen Braun ◽

Johannes Bruns ◽

Miroslav Černík ◽

Peter Rissing ◽

...

Keyword(s):

Groundwater Remediation ◽

Zero Valent Iron ◽

Nanoscale Zero Valent Iron

Download Full-text

The decreasing aggregation of nanoscale zero-valent iron induced by trivalent chromium

Environmental Chemistry ◽

10.1071/en16144 ◽

2017 ◽

Vol 14 (2) ◽

pp. 99

Author(s):

Danlie Jiang ◽

Xialin Hu ◽

Rui Wang ◽

Yujing Wang ◽

Daqiang Yin

Keyword(s):

Aquatic Environment ◽

Groundwater Remediation ◽

Trivalent Chromium ◽

Zero Valent Iron ◽

Environmental Behaviour ◽

Magnetic Attraction ◽

Aggregation Behaviour ◽

Nanoscale Zero Valent Iron ◽

Magnetite Content ◽

Acidic Conditions

Environmental contextNanoscale zero-valent iron is a promising material for environmental engineering and groundwater remediation. However, the environmental behaviour and fate of nanoscale iron that is essential for applications and risk assessment is still uncertain. We report a study on the aggregation behaviour and mobility of nanoscale iron in the aquatic environment using colloidal chemical methods. AbstractDespite high magnetisation, nanoscale zero-valent iron (nZVI) exhibits weak aggregation when treating hexavalent chromium (CrVI) (0.02mmol L–1) under anaerobic circumstances, which leads to the enhancement of its mobility in the aquatic environment. To elucidate such an unexpected phenomenon, the influences of different valences of chromium on the aggregation behaviour of nZVI were examined. Results indicate that trivalent chromium (CrIII) greatly decreases the aggregation of nZVI in acidic conditions (pH 5), while little influence is observed at a higher pH (pH 7). We suggest that such influences are mainly a result of precipitation on the surface of nZVI particles, which prevents the formation of chain-like aggregates. Accordingly, although the particles are highly magnetic (magnetite content >70%, saturation magnetisation=363 kA m–1), the magnetic attraction between aggregates and particles is not strong enough to promote further aggregation. Furthermore, the Cr(OH)3 shell blocks collisions between particles and greatly enhances their zeta-potential, which also assists in preventing aggregation. Our results suggest that heavy metals can significantly affect the environmental behaviours of nanoparticles.

Download Full-text

Review on remediation of contaminated groundwater by Fe0-PRB technology

E3S Web of Conferences ◽

10.1051/e3sconf/202123701019 ◽

2021 ◽

Vol 237 ◽

pp. 01019

Author(s):

Xiaohui Zhang ◽

Xiaodong Wang ◽

Xianfeng Sun

Keyword(s):

Groundwater Remediation ◽

Preparation Method ◽

Zero Valent Iron ◽

Contaminated Groundwater ◽

Pilot Test ◽

Application Technology ◽

Remediation Technology ◽

Test Stage ◽

Working Principle ◽

At Home

PRB technology is a new groundwater remediation technology, which is currently in the pilot test stage in China. Zero-valent iron is one of the most commonly used fillers in permeable reaction walls. In this paper, the principle and structure of PRB technology, the working principle of zero-valent iron in PRB, the preparation method and the optimization and improvement of application technology, the application examples at home and abroad and the prospect of PRB technology are introduced.

Download Full-text

Improved Affinity of Nanoscale Zero Valent Iron toward Hydrophobic Organic Solvent using Poly(1-vinylpyrrolidone-co-vinyl acetate)

Journal of Korean Society of Environmental Engineers ◽

10.4491/ksee.2020.42.9.431 ◽

2020 ◽

Vol 42 (9) ◽

pp. 431-441

Author(s):

Jeongmin Hong ◽

Hayeon Yang ◽

Taeyeon Cha ◽

Younggyo Seo ◽

Yuhoon Hwang

Keyword(s):

Particle Size ◽

Porous Media ◽

Vinyl Acetate ◽

Soil Remediation ◽

Organic Contaminants ◽

Nitrate Reduction ◽

Groundwater Remediation ◽

Reduction Rate ◽

Zero Valent Iron ◽

Nanoscale Zero Valent Iron

Objectives : Levels of organic contaminants in excess of the standard minimum have been detected in many commercial and residential sites, and the severity of soil and groundwater pollution is increasing. In particular, non-aqueous phase liquids (NAPLs) are hydrophobic organic pollutants that do not mix with water and are difficult to remove with existing soil remediation technology. These pollutants slowly dissolve into the groundwater over long periods of time, thus contaminating the groundwater. With the increasing need to remove NAPLs for soil and groundwater remediation, widespread interest has focused on the use of nanoscale zero valent iron (nZVI). However, nZVI has the disadvantage of reduced subsurface mobility. Hence, in the present study, the nZVI surface is modified with poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA), which has both hydrophilic and hydrophobic groups, to improve the mobility and selectivity of nZVI for the removal of NAPL.Methods : The PVP/VA modified nZVI is synthesized through the reaction of FeSO4･7H2O and NaBH4 in the presence of PVP/VA. To confirm the dispersibility of the prepared material, a precipitation experiment is performed using a visible light spectrometer, and the mobility through a sand-filled column is evaluated. In addition, the variation in particle size and characteristics according to the presence of PVP/VA is examined via transmission electron microscopy. The nitrate reduction ability of nZVI with PVP/VA is also evaluated to reveal changes in reactivity depending upon the degree of dispersion. To confirm the selective mobility towards NAPL, trichloroethylene and dodecane are used to evaluate the mobility with and without PVP/VA. Finally, the ratio of nZVI passing through the sponge layer absorbing dodecane is evaluated to determine the selective mobility towards NAPL in the porous medium.Results and Discussion : Although the dispersibility of the PVP/VA-nZVI is not significantly changed, the particle size is significantly decreased. Both the mobility in porous media and the nitrate reduction rate are improved via PVP/VA modification. The affinity for hydrophobic contaminants and the selective migration of PVP/VA-nZVI towards the NAPL layer are also improved. The high affinity for the NAPL was also shown by the column with NAPL layer.Conclusions : Surface-modification with PVP/VA, which has both hydrophilic and hydrophobic ends, enabled the synthesis of nZVI with a smaller and more uniform particle size, thus providing high mobility in porous media and high reactivity towards contaminants. The combined hydrophilicity and hydrophobicity of PVP/VA is shown to increase the affinity of nZVI towards NAPL and, thus, promote its migration to the NAPL layer. Thus, it is anticipated that the efficiency of soil remediation can be improved by promoting the movement of nZVI towards the target NAPL layer.

Download Full-text

Effects of common dissolved anions on the reduction of para-chloronitrobenzene by zero-valent iron in groundwater

Water Science & Technology ◽

10.2166/wst.2011.392 ◽

2011 ◽

Vol 63 (7) ◽

pp. 1485-1490 ◽

Cited By ~ 19

Author(s):

C. Le ◽

J. H. Wu ◽

S. B. Deng ◽

P. Li ◽

X. D. Wang ◽

...

Keyword(s):

Humic Acid ◽

Groundwater Remediation ◽

Reduction Rate ◽

Zero Valent Iron ◽

Iron Surface ◽

Contaminated Groundwater ◽

Carbonate Complex ◽

Ion Concentrations ◽

Batch Tests ◽

Inner Sphere Complexes

Batch tests were conducted to evaluate the influences of several common dissolved anions in groundwater on the reduction of para-chloronitrobenzene (p-CNB) by zero-valent iron (ZVI). The results showed that p-CNB reduction was enhanced by both Cl− and SO42−. HCO3− could either improve or inhibit p-CNB reduction, depending on whether the mixing speed was intense enough to rapidly eliminate Fe–carbonate complex deposited on ZVI surface. Above a concentration of 100 mg L−1, NO3− increased the p-CNB reduction rate. The reduction rate by ClO4− decreased because the ClO4− competed with p-CNB for electrons. The p-CNB reduction was inhibited by PO43−, SiO32− and humic acid, in the order humic acid < PO43− < SiO32−, since these ions could form inner-sphere complexes on iron surface. The reaction even ceased when the ion concentrations were greater than 4, 0.5, and 30 mg L−1, respectively. The results indicated that common dissolved anions in groundwater should be taken into account when ZVI is applied for contaminated groundwater remediation.

Download Full-text