Uptake and biosorption potential of Pistia stratiotes for Cr6+.

Uptake and biosorption potential of Pistia stratiotes for Cr6+ was examined. The study was conducted in two phases: in the first phase, the effect of different Cr6+ concentrations on plant weight, leaf number and root length was determined along with plants uptake potential. Higher concentration of Cr6+ (> 8 ppm) had inhibitory effects on increase in plant weight due to impairment of the metabolic machinery. Leaf number and root length showed no increase when exposed to a Cr6+ concentration of ~ 10 ppm. When grown in solutions containing 2, or 4 ppm Cr6+ concentrations, P. stratiotes removed 100% of Cr6+. However at increasing concentrations of 6 and 8 ppm, only 50% reduction in respective solutions was recorded. In a second phase biosorption capacity of dead P. stratiotes was determined. The optimal pH range for maximum Cr6+ biosorption lied between 1-2. Maximum biosorption capacity of dead biomass was recorded at 200 ppm of the initial Cr6+ concentration. The volume and pH of a Cr6+ solution passing through the columns were critically important affecting the biosorption capacity of P. stratiotes. These findings are important for cost-effective and environmental friendly removal of Cr6+ from tannery effluents which are posing serious risk to human and environmental health in tannery hubs of Pakistan. [ABSTRACT FROM AUTHOR]