Avena fatua as a natural biosorbent for Cu(II) and Zn(II) and the effect of these metals on weed growth

MARIA DEL MAR ARECO; MARIA DOS SANTOS AFONSO

Vancouver, BC. Canada

Congreso; 5th International Weed Science Congress; 2008

International Weed Science Society, Canadian Weed Science Society, Weed Science Society of America

Justification for the research Metal contamination is consider one of the most concerning types of contamination, they are bio accumulated along the trophic chain and are discarded from an enormous number of different industries, being the environment the disposal storage. During the past few years different ways of effluent treatments are being studied. Plants, such as weeds, can be used as biosorbents for metal uptake from the environment because metals are taken by plants and can be accumulate in them. Objectives The objective is to determinate if Avena fatua can be used as a metal biosorbent substrate in order to remove Cu(II) and Zn(II) from waste waters, as well as to determine the effect of these metals onto A. fatua growth when it is treated with different concentrations of metal solutions. Methods A. fatua was collected in Buenos Aires, Argentina. Seeds were separated. The biomass was washed, dried and crushed. Batch biosorption experiments were carried out using solutions of Zn(II) and Cu(II). Assays were conducted with a fixed metal (50 mg/l) and weed (1 g/l) concentrations for 24 hours. Aliquots of the different solutions were filtered and analyzed by spectrophotometric techniques. Kinetic biosorption experiments were carried out for both metals at the best pH value for metal removal (pH=5). The Langmuir sorption model was chosen for the estimation of maximum metal uptake (qmax). The effect of Zn(II) and Cu(II) concentration on A. fatua growth was studied by planting two seeds of A. fatua on each of a total of 22 flowerpots. The flowerpots were grouped in pairs and each pair was irrigated with a different metal concentration solution (1, 10, 20, 50 and 100 ppm), two of them were used as controls so they were irrigated only with tab water. Results A. fatua biosorbs Cu(II) and Z(II). Adsorption of copper was much more efficient than zinc. Maximum metal equilibrium concentration was reached after three hours for both metals. A. fatua biosorbs more than 30% of the initial Cu(II) concentration in the solution. This result confirms the capacity of this weed to biosorb copper from waste waters. Zn(II) uptake were much less efficient. The effect of metal concentration on A. fatua growth was marked. The effect of zinc concentration for the development of A. fatua was less than the copper effect. Conclusions A. fatua can be used as a biosorbent for Cu(II) uptake from contaminated effluents. For the uptake of Zn(II) other kind of biomasses should be considered, such as seaweeds, which are much more efficient for Zn(II) biosorption from waste waters. Natural substrates should be considered as an alternative technique for effluent treatment. Metals affect A. fatua growth. The presence of copper on the water affect more the growth of this weed than the same concentration of Zn(II).