Synergistic Effects of Multiple Metal Contaminants on Electrokinetic Remediation of Soils

Abstract

This article presents a bench‐scale study performed to investigate the removal of heavy metals when they exist individually and in combination in soils. Electrokinetic experiments were conducted using two types of clayey soils, kaolin and glacial till. These soils were contaminated with Cr(VI) only, with Ni(II) only, and with Cr(VI), Ni(II), and Cd(II) combined. It was found that in kaolin, a significant pH variation occurred due to electric potential application, affecting the adsorption‐desorption and dissolution‐precipitation, as well as the extent of migration of the contaminants. In glacial till, however, pH changes were not affected significantly. In both kaolin and glacial till, the migration of Cr(VI) and Ni(II) was higher when they were present individually compared to when they existed together with Cd(II). Cr(VI) migration as single or combined contaminant was lower in kaolin as compared to that in glacial till. This result was due to the low pH conditions created near the anode region in kaolin that led to high Cr(VI) adsorption to the clay surfaces. In glacial till, however, nickel precipitated with or without the presence of co‐contaminants due to high pH conditions in the soil. Overall, this study demonstrates that adsorption, precipitation, and reduction are the significant hindering mechanisms for the removal of heavy metals using electrokinetic remediation. The direction of the contaminant migration and overall removal efficiency depend on the polarity of the contaminant, the presence of co‐contaminants, and the type of soil. © 2001 John Wiley & Sons.

Performance of electroremediation in real contaminated sediments using a big cell, periodic voltage and innovative surfactants

“…8-17 mS cm -1 ) in sections near the anode, he lowest values in the middle of the cell and finally increasing trends towards the sediment slices close to the cathode. Such behaviour, that has also been reported in other studies [14,49] can be attributed to the strong presence of ionic particles near the anode and to the absorption and/or precipitation of metals due to high pH near the cathode. on the maximum removal percentages obtained (see Fig.…”

Surface Speciation Modeling of Heavy Metals in Kaolin: Implications for Electrokinetic Soil Remediation Processes

“…Adsorption/desorption process is one of the important physico-chemical processes affecting the transport of the heavy metals during electrokinetics (Reddy et al, 2001;Reddy and Parupudi, 1997). This importance stems from the fact that the pH and solution chemistry change throughout the soil during electrokinetics, affecting the adsorption/desorption process.…”

Correlation of the Physicochemical Properties in Soils from Tenerife Island, Measuring the Electric Current in an Electrokinetic Experiment

“…Entre estas magnitudes, la corriente de electrólisis, cuando se trabaja a potencial aplicado constante, es una de las reportadas habitualmente en la literatura científica [1][2][3][4][5][6][7][8][9][10][11][12]. Entre otros, podemos destacar estudios encaminados a la eliminación de metales pesados tales como Pb, Cd, Cr, Ni, Cu y Zn [1,5,7,[8][9][10][11][12], en los que la corriente † Dedicado a la Dra. …”

“…Por otra parte, estudios sobre la disminución de la salinidad de suelos o la utilización de agentes complejantes como EDTA [2][3] para favorecer la eliminación de metales, han recurrido al análisis de la corriente de electrólisis con respecto al tiempo, para discutir sus resultados. También se ha utilizado dicho análisis en experimentos de electrorremediación que utilizan membranas selectivas a cationes en el proceso de eliminación de contaminantes [4], en estudios de la influencia de la capacidad buffer del suelo sobre el rendimiento de la eliminación [10] o en el estudio de procesos de eliminación múltiple simultánea [7]. Por último, cabe decir que en los últimos años, nuestro grupo de investigación ha llevado a cabo una serie de experiencias de "electro-caracterización" de suelos [13][14][15][16][17][18], en los cuales también se hace uso de la medida de la corriente de electrólisis.…”