Transient behavior of heavy metals in soils during electrokinetic remediation

Al-Hamdan, Ashraf Z.; Reddy, Krishna R.

doi:10.1016/j.chemosphere.2007.11.028

Cited by 111 publications

(56 citation statements)

References 20 publications

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“…Al-Hamdan and and Al-Hamdan (2002) conducted a series of batch adsorption experiments and showed that the adsorption behavior of Cr(VI), Cr(III), Ni(II), and Cd(II) by glacial till can be described by a non-electrostatic adsorption models (i.e., Freundlich models). The adsorption parameters were determined by performing regression analysis for the experimental adsorption results.…”

Section: Adsorption Experimental Datamentioning

confidence: 99%

Geochemical assessment of metal transport in glacial till during electrokinetic remediation

Al-Hamdan

Reddy

2007

Environ Monit Assess

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This paper presents the chemical speciation and retention behavior of chromium (Cr), nickel (Ni), and cadmium (Cd) prior to and after the electrokinetic remediation in glacial till soil. The speciation of the metals was predicted using the chemical speciation program MINEQL(+). The simulations were performed for single-contaminant with only Cr(VI) or Ni, and multi-contaminants consisting of: (1) Cr(VI), Ni, and Cd; (2) Cr(III), Ni and Cd; (3) Cr(VI), Cr(III), Ni and Cd; (4) Cr(VI), Ni, and Cd with reducing agents; and (5) Cr(III), Ni, and Cd with oxidizing agent (Mn). The results showed that the speciation and distribution of cationic metals [Ni, Cd, and Cr(III)] in glacial till soil remain unaffected or slightly affected during electrokinetics. This is attributed to the high pH buffering capacity of the glacial till, leading the metals to precipitate in the soil prior to and after electrokinetics. This study showed that during electrokinetics, Cr(VI) existed as anionic complex and migrated towards the anode and the migration is maximum in case of a single-contaminant system. The study also showed that near the anode in the absence of any reducing and oxidizing agent, Cr(VI) mostly adsorbed, and some of Cr(VI) reduced to Cr(III) and migrated towards the cathode and finally precipitated due to high pH conditions. Ni and Cd remain adsorbed or precipitated due to the high pH conditions throughout the soil. Among the reducing agents, the sulfide had significant effect on the migration of metals compared to ferrous ions. While in the presence of oxidizing agent (Mn), no noticeable Cr(VI) was found in the soil sample indicating the reduction of Cr(VI) to Cr(III) and the predominance of reducing conditions due to the presence of naturally occurring iron in the glacial till soil. Overall, this study provides a reasonable explanation of the speciation and distribution of chromium, nickel and cadmium during the electrokinetic remediation of glacial till soil.

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Section: Adsorption Experimental Datamentioning

confidence: 99%

Geochemical assessment of metal transport in glacial till during electrokinetic remediation

Al-Hamdan

Reddy

2007

Environ Monit Assess

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“…Modeling of the surface speciation can be used to predict the trends in adsorption behavior of heavy metals in soils with master variables such as pH and redox status. Application of sound thermodynamic principles to adsorption reactions provides a modeling framework that is theoretically rigorous, which can be applied for even complex adsorption reactions (Grenthe and Puigdomenech, 1997;Al-Hamdan, 2002).…”

Section: Introductionmentioning

confidence: 99%

“…The actual nature of the association between the charged surface and the counterions depends on the mechanism of retention of the counterion with the surface i.e., the extent of adsorption depends on either the respective charges on the adsorbing surface and the metallic cation or on the intrinsic formation constants for the complexation reactions. Various models have been developed to predict and quantify the adsorption/ retention of metals by charged soil surfaces and are discussed in Schecher and McAvoy (1994) and Al-Hamdan (2002).…”

Section: Introductionmentioning

confidence: 99%

Adsorption of heavy metals in glacial till soil

Al-Hamdan

Reddy

2006

Geotech Geol Eng

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The charged sites on soil particles are important for the retention/adsorption of metals. Metallic counterions can neutralize the intrinsic charges on the surfaces of soil particles by forming complexes. In this study, efforts have been made to determine the effect of surface potential, pH, and ionic strength on the adsorption of four metal ions, hexavalent chromium Cr(VI), trivalent chromium Cr(III), nickel Ni(II) and cadmium Cd(II), in glacial till soil. Batch tests were performed to determine the effect of pH (2-12) and ionic strength (0.001-0.1 M KCl) on zeta potential of the glacial till soil. The point of zero charge (pH PZC ) of glacial till was found to be 7.0±2.5. Surface charge experiments revealed the high buffering capacity of the glacial till. Batch adsorption experiments were conducted at natural pH (8.2) using various concentrations of selected metals. The adsorption data was described by the Freundlich adsorption model. Overall glacial till shows lower adsorption affinity to Cr(VI) as compared to cationic metals, Cr(III), Ni(II) and Cd(II).

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“…The biggest contributor to contaminant transport processes in the soil depends largely on the type of contaminants (organic or inorganic), soil type, water content, ion species as well as its concentration. Normally the mass transport by electromigration, is 10-300 times greater than the mass transport by electroosmosis advection [1][2]. In addition, continuous electrochemistry process will cause the soil pH to become more acidic and gradually drop the soil particle zeta potential, thus reducing the electroosmosis process [3].…”

Section: Introductionmentioning

confidence: 99%