Abstract

Heavy metals constitute a serious health risk because they accumulate in soils, water and organisms. One of the methods of removing these pollutants from water and soil is the use of plants. There are many plants (hyperaccumulators) which have the ability to accumulate large amounts of heavy metals. One of them is the aquatic fern Azolla filiculoides, which can bind some substances. A dried A. filiculoides biomass was used to remove heavy metal from aqueous solution using batch experiments. The aim of this study was to verify the ability of A. filiculoides to fix Ni and Cu from polluted waters. The maximum uptake capacities of the collected A. filiculoides from the Asbchin Wetland west of Mazandaran in the northern part of Iran at the optimal conditions for Ni and Cu ions were approximately 0.77 and 0.54 mmol/g (dry Azolla), respectively. Fourier transform infrared (FT-IR) spectroscopy was used to examine functional groups that may take part in the dried A. filiculoides biomass. Results showed that the amino, carboxyl and hydroxyl groups may be responsible for the biosorption of metal ions on the biomass. Desorption experiments indicated that ethylenediaminetetraacetic acid (EDTA), HNO₃ and HCl were efficient desorbents for recovery from Ni (II) and Cu (II).

Key words: Azolla filiculoides, wastewater, batch biosorption, heavy metals