Adsorptive uptake of arsenic (V) from water by aquatic fern Salvinia natans

Abstract

The sorption potential of the As (V) ion from aqueous solution has been studied using the water fern Salvinia natans as a scavenging candidate for aquatic arsenic. Sodium arsenate was used to prepare the stock solution of As (V). The diluted stocks with nutrient as sample solutions with As-free pond water were kept in different Perspex cells of a multiple chamber and for each concentration a varying amount of dry mass of the plants were nourished under adequate lighting for supporting the growth of the plants. The samples were drawn from each chamber at 24 h intervals up to 5 days and for each sample the residual As (V) was estimated by the silver diethyl dithio carbonate (SDDC) method. Test results indicate that the plant could effectively uptake As (V) between 0.25 and 2 mg l−1 to the extent of 74.8 to 54%, respectively, after 120 h contact time for a plant mass of 20 g l−1 at neutral pH. The experimental data were fitted well to both Langmuir and Freundlich isotherms. The effect of pH and biomass quantities on sorption rate have been also investigated along with some metabolic parameters.