Phytofiltration of Chromium (Cr) and Manganese (Mn) from polluted waters using Luffa Cylindrica

The phytofiltration potential of Luffa Cylindrica (sponge and seeds) to remove Mn2+ and Cr3+ from aqueous solutions was studied. The effect of various parameters on the removal process was investigated. Such parameters included; pH, initial concentration of metal ion, temperature, and contact time. The binding capacity of seeds with the metal ion (mg/g) was determined. The effect of the presence of other competing ions was also studied. Adsorption isotherms were investigated, the reaction order and Gibbs free energy were determined. The results showed that the maximum percent removal of Cr3+ by sponge and seeds were 42% and 40% respectively, while were 82% and 78% for the removal of Mn2+ respectively. The optimum pH was 5.0 for the removal of Cr (III) and 7.0 for Mn (II). The percent removal of metal ions was optimum at initial concentration of 5 mg/L, a temperature range of 35°C - 40°C, and a contact time of 30 minutes. The equilibrium concentration of metal ions in solution was followed by using flame atomic absorption spectrometry. Binding capacity of seeds was 1.7 mg/g for Cr (III) and 3.4 mg/g for Mn (II). The results of the uptake of Cr (III) by seeds fit well with the Langmiur adsorption isotherm, while Freundlich adsorption isotherm was found to be more applicable for the removal of Mn (II) by seeds. The binding of both metal ions with seeds followed a second order kinetics. The values of Gibbs free energy were also determined.