Influence of nickel speciation on electrokinetic sediment remediation efficiency

Abstract

This article presents a bench-scale investigation of nickel removal during electrokinetic (EK) remediation of sediment, and the dependency of removal efficacies upon the speciation of the metal, as influenced by the duration of the nickel-sediment interaction. The sediment used in this study was from the Grand Backa canal (Vojvodina, Republic of Serbia). The sediment used is anaerobic and the nickel pollution has been aged for several years, so it is mostly sorbed by sulphides and organic mater (57%). In EXP I, conventional EK remediation was conducted on this sediment for 7 days, but was ineffective (0% removal). EXP II investigated the influence of the duration of nickel sorption onto the sediment, by contaminating the sediment with additional nickel. In this sediment, nickel appeared mainly in the most mobile, acid-soluble fraction, and was thus available for migration towards the cathode. Consequently, conventional EK remediation of this sediment resulted in significantly better nickel removal (23%) than EXP I. During EXP III, the same spiked sediment was investigated using an increased applied current density, with no significant increase in removal efficacy. This study demonstrates that metal-sediment interaction duration affects efficacy of metal removal during EK remediation.

Keywords

• electrokinetics
• remediation
• sediment
• nickel
• speciation