In this work, the phytoremediation of Cr (VI) and Hg (II) ion from water by an aquatic plant Eichhornia crassipes has been studied. Plants were cultured in a double distillated water with modified Hoagland’s nutrient solution at pH 6.8 supplemented with 0, 0.75, 1.50, 2.50, and 4 mg Cr/L as potassium dichromate (K2Cr2O7) and 0, 5, 10, 15, and 20 mg Hg/L as mercuric chloride (HgCl2). They were separately harvested after 3, 6 and 9 days. Plants treated with 4 mg/L of Cr (VI) accumulated the highest concentration of metal in roots (1.22 mg/g, dry weight) and shoots (0.24 mg/g, dry weight) after 9 days; while those treated with 20 mg/L of Hg (II) accumulated the highest concentration of metal in roots (4.22 mg/g, dry weight) and shoots (2.43 mg/g, dry weight) after 9 days. Eichhornia crassipes biomass was characterised using AAS, SEM and FTIR. The accumulation and relative growth of metal ions at different concentrations of chromium and mercury solution significantly increased (P<0.05) with the passage of time. The maximum values of bio-concentration factor (BCF) for Cr (VI) and Hg (II) were found to be 413.33 and 502.40 L/kg respectively.
Keywords: accumulation, bio-concentration, chromium (VI), Eichhornia crassipes, mercury (II), phytoremediation
