The application of ultrasonic treatment and a bis(2-ethylhexyl)sulfosuccinate-based novel ionic liquid for cadmium extraction

Abstract

A hydrophobic functional ionic liquid (IL) [N₄₄₄₄]AOT based on bis(2-ethylhexyl)sulfosuccinate anions was designed and synthesized for cadmium extraction. To study the characteristics of [N₄₄₄₄]AOT, Fourier transform infrared (FTIR) spectroscopy, hydrogen nuclear magnetic resonance spectroscopy (¹H NMR), and thermogravimetric analysis were used. The extraction ability of [N₄₄₄₄]AOT towards Cd under ultrasonic conditions was also investigated. The results showed that more than 95.08% of Cd in a water solution could be extracted with [N₄₄₄₄]AOT under ultrasonic conditions. The results of FTIR and ¹H NMR analyses showed that Cd mainly coordinated with the S–O bond provided by [N₄₄₄₄]AOT during extraction. The extraction of Cd from soil with [N₄₄₄₄]AOT was high and reached the value of 62.57%. Furthermore, [N₄₄₄₄]AOT could extract some stable and bound Cd species from the soil, which existed in a weakly acidic, reducible or oxidizable state. The application of [N₄₄₄₄]AOT significantly decreased the bioavailability of Cd in the soil. [N₄₄₄₄]AOT can be a good agent for Cd-contaminated soil remediation without changing the soil properties.