Studies On The Physicochemical Remediation Of Hexachlorobenzene Contaminated Soils

Hexachlorobenzene (HCB) is a typical persistent organic pollutant (POPs). HCB contained in water and air tends to accumulate in soils and sediments, it is therefore of importance to develop effective technology to remediate the contaminated soils and sediments. This paper reviewed the soil remediation technology firstly, investigated the MnO₂ enhanced microwave (MW) remediation of HCB contaminated soils and the electrokinetic (EK) remediation of HCB contaminated soils enhanced by facilitating agents.The results of the paper were concluded in the following:(1) The mechanism of the decomposition of HCB using MnO₂ as MW absorber is very complex because many chemical reactions were involved under MW radiation. The viability was primarily denied by the harsh conditions required (≥50%H2SO4). However, this study provided insight inforation on the behavior of MnO₂ in MW radiation and offered guidance for the selection of MW absorbers. In contrast, powdered Fe restricted the decomposition of HCB in the first stage in basic media and had slight enhancement on the decomposition in acidic and neutral media. The mechanism of the decomposition of HCB with Fe was proposed to be similar to that with MnO₂.(2) The desorption sequence of HCB on soil with different facilitating agents were obtained to be: Tween80 > HTAB (Hexadecyl trimethyl ammonium bromide) >>β- Cyclodextrin > SDS (sodiumdodecylsulfonic)> H₂O.(3) The addition of 1% Tween80 to Na₂CO₃/NaHCO₃ buffer used as anodic purging solution showed significant enhance ment effect on the EK properties such as electric current, electroosmatic flow, moisture and pH distribution, and obtained more obvious HCB migration.