Study on the removal of chromium(III) by solvent extraction

abstract

The extraction of chromium(Ш) from aqueous waste solution by extractants 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (HEHPEHE), di(2-ethylhexyl) phosphoric acid (D2EHPA), and mixture of D2EHPA with other extractants is carried out, respectively. It is found that the extractant HEHPEHE exhibited high extraction selectivity for chromium(III) from aqueous waste solution. Based on the molecular structure of HEHPEHE, it is confirmed that the extraction mechanism of chromium(III) by HEHPEHE is mainly determined by cation exchange and chelation. Furthermore, the influences of major factors, such as the initial pH, the initial concentration of extractant, phase ratio, and the extraction temperature on the extraction efficiency of chromium(III) are also investigated and the appropriate process conditions are obtained. At the appropriate conditions, the extraction efficiency of chromium(III) above 99% can be achieved and the treated aqueous waste solution can be discharged directly without polluting the environment.

Keywords:

• Extraction process
• HEHPEHE
• Chromium(III)

Acknowledgments

The authors gratefully acknowledge the financial support of this work by Eleventh Five Year National key Technology R&D program (No.2008BAE58B01) and New Century Excellent Talents of Ministry of Education (NCET-07-0577), the People’s Republic of China.