Ultrasound-assisted treatment of kaolin artificially contaminated with henanhtrene, fluoranthene and hexachlorobenzene

Application of ultrasound in decontamination of polluted soil is a new and promising technology. The feasibility of ultrasonic treatment of clayey soil (kaolin) highly contaminated with persistent organic pollutants (POPs), such as phenanthrene (PHE), fluoranthene (FLU), hexachlorobenzene (HCB), was the main target of the work. The laboratory experiments were conducted at various conditions (moisture, power, irradiation duration and the initial concentration of contaminants) and the effects of these parameters on the process efficiency were examined. Experimental results showed that ultrasonication alone has a potential to remove POPs, although the removal efficiencies were relatively low when a short irradiation duration (1-6 hours) was adopted. Intermittent ultrasonication over longer periods (up to the total of 46 hours) increased the removal efficiencies to 45% of HCB and nearly 100% of PHE. The optimum moisture content of the slurry was found to be in the range of 50-70%. The total electric energy consumption during the experiments using the optimum operational conditions (100 W and above ultrasound irradiation power and 67% moisture content) was 1.5 kWh in comparison to 1.84 kWh during experiments utilizing minimum operational conditions.