Treatment of Oilfield Soils Contaminated With ²²⁶Ra, ²¹⁰Pb and ²¹⁰Po Using Ultrasound and Acid Washing

A method to treat soils contaminated with ²²⁶Ra, ²¹⁰Pb and ²¹⁰Po using ultrasonic waves has been developed. Diluted acidic solutions were used as washing media for the radionuclides. The optimum treatment conditions such as the ratio of soil to solution, contact time, temperature, concentration of washing solution, and soil particle size have been determined. The results showed that the efficiency of soil washing using ultrasonic waves could reach 95% for both ²²⁶Ra and ²¹⁰Pb. The acidic solutions HCl (5%) and HNO₃ (5%) were found to give the highest removal efficiency for ²²⁶Ra and ²¹⁰Pb. On the other hand, the efficiency of ultrasonic treatment was found to be inversely related to both electrical conductivity of soil solution, the concentration of dissolved ions (Cl^-, HCO^3-, Ca²⁺, and Mg²⁺), and the concentration of organic matter in the soil. However, the method may be useful for treatment of the oilfields soil contaminated with ²²⁶Ra, ²¹⁰Pb and ²¹⁰Po.