Desorbing of decabromodiphenyl ether in low permeability soil and the remediation potential of enhanced electrokinetic

Abstract

In this study, desorption kinetic was determined for decabromodiphenyl ether (BDE209) in a low permeability soil, and the remediation potential of hydroxypropyl-β-cyclodextrin (HPCD) enhanced electrokinetic (EK) technique was investigated. The results indicated that the release rate of BDE209 in slowly and very slowly desorbing process was accounted for 31% and 68% in the whole desorption process, respectively. The final desorption rate of BDE209 was 20.7% after 70 h treatment with 5% HPCD in an ideal solution reaction system (without electric field). However, the removal efficiency of BDE209 in section S5 (near anode) of EK1 and EK2 had reached 22% and 20% after 14 days treatment, respectively. Thus it can be assumed that the interaction between BDE209 (on soil particles) and HPCD had been promoted under the electric field. A higher cumulative EOF did not remove more BDE209 with HPCD as facilitating agent, which might due to the low viscosity of HPCD and it did not react completely with BDE209 in soils. In addition, the removal efficiency of BDE209 in section S5 of CK1 and CK2 (without HPCD) had reached 6% and 10%, respectively, which might attribute to the desorption promoting effect of the uniform electric field on hydrophobic organic contaminants. In summary, it is feasible to use the EK to remove BDE209 in low permeability soils using HPCD as solubilizing agent, and the technique key is maintaining sufficient EOF and ensuring the contact reaction efficiency between HPCD and BDE209 synchronously.