Surfactants-enhanced electrokinetic transport of xanthan gum stabilized nanoPd/Fe for the remediation of PCBs contaminated soils

摘要

Polychlorinated biphenyls (PCBs) in the environment pose long-term risk to public tiealth because of their persistence and toxicity. In this study, a novel technology called EK + nano (electrokinetic technology combined with engineered nanoparticles) was used to remediate polychlorinated biphenyls (PCBs) contaminated soil. Three different surfactants (anionic surfactant - SDBS, nonionic surfactant - Brij35 and biosurfactant - rhamnolipid) for enhancing the solubilization of soil PCBs were applied separately with xanthan gum stabilized nanoPd/Fe. The stabilized nanoPd/Fe was injected in the compartment located 3 cm from the anode chamber daily in EK tests. The results indicated that the surfactants addition enhanced the solubilization capacity of PCB28 significantly but did not affect the stability of xanthan gum-nanoPd/Fe suspension. The nanoparticles were successfully transported along with the soil column by EK, and apparent increase of Fe content was found toward the cathode. Higher electroosmotic flow favored the migration of nanoparticles, but the degradation was limited without addition of surfactant. Brij35-xanthan gum stabilized nanoPd/Fe gave the highest removal efficiency of PCBs, both in batch experiments and EK tests, in which the removal rates of approximately 50% and 20% were achieved, respectively. The functions of SDBS and rhamnolipid in soil PCBs removal were not significant in all tests.