Abstract

The present study focuses mainly on the efficiency of surfactants sodium dodecyl sulfate (SDS), sodium dioctyl sulfosuccinate (AOT) and Triton X-100 (Tx-100) for the extraction of heavy metals Cr (VI), Ni (II) and Zn (II) from an artificially contaminated sandy soil. In addition, it also discusses metal extraction by a complexing agent EDTA with or without the addition of surfactants. To investigate metal extraction efficiency, both batch and column studies were performed. In batch studies, all surfactants are found to be nearly 2 to 3 times more effective for Cr (VI) removal, 3.0 to 6.2 times more effective for Ni (II) removal and 1.75 to 2.88 times more effective for Zn (II) removal, compared to the metal extraction by distilled water alone. Compared to the metal extraction by distilled water alone, metal extraction by EDTA in combination with SDS was 11 times greater for Cr (VI) removal, 8.07 times greater for Ni (II) removal and 4.94 times greater for Zn (II) removal, Column studies showed that 50 pore volumes of water alone can remove about 18% of Cr (VI), 19% of Ni (II) and 20% of Zn (II). On the other hand, at 50 pore volumes, the amount of Cr (VI), Ni (II) and Zn (II) removal by SDS appears to be relatively high about 24%, 27% and 33% respectively. However, injections of 50 pore volumes of SDS with EDTA were able to elute about 57% of Cr (VI), 67% of Ni (II) and 71% of Zn (II). These results suggest that surfactants do improve the efficiency of soil washing by enhancing the extraction of heavy metals such as chromium, nickel and zinc