Removal of toxic metals from solution by leaf, stem and root phytomass of Quercus ilex L. (holly oak)

Increased consciousness for safeguarding the aqueous environment has prompt ed a search for alternative technologies for the removal of toxic metal ion s from aqueous solutions. In this regard, a wide variety of biomass is bein g considered as adsorbents of heavy metals for treatment of industrial and domestic wastewaters as well as natural waters, including drinking water. I n the present investigation, the potential of Quercus ilex phytomass from s tem, leaf and root as an adsorbent of chromium (Cr), nickel (Ni), copper (C u), cadmium (Cd) and lead (Pb) at ambient temperature was investigated. The metal uptake capacity of the root for different metals was found to be in the order: Ni > Cd > Pb > Cu > Cr; stem Ni > Pb > Cu > Cd a Cr; and leaf Ni > Cd > Cu > Ph > Cr. The highest amount adsorbed was Ni (root > leaf > ste m). Data from this laboratory demonstrated that Ni is sequestered mostly in the roots, where concentrations can be as high as 428.4 ng/g dry wt., when 1-year-old seedlings were treated with Ni (2000 mg/l) in pot culture exper iments, compared to 7.63 ng/g dry wt., control (garden and greenhouse soil) topsoil where Ni was present in trace amounts. This proves that the root b iomass of Q. ilex has the capacity for complexing Ni. Cr exhibited the leas t adsorption values for all the three types of phytomass compared to other metals. The trend of adsorption of the phytomass was similar for Ni and Cd, i.e. root > leaf > stem. Desorption with 10 mM Na-4 EDTA was effective (55 -90%) and, hence, there exists the possibility of recycling the phytomass. The biosorption results of recycled phytomass suggest that the selected ads orbents are re-usable. The advantages and potential of the Q. ilex phytomas s as a biofilter of toxic trace metals, the scope and need for enhancing th e efficiency of the Q. ilex phytomass as an adsorbent of metals are present ed. (C) 2000 Elsevier Science Ltd. All rights reserved.