Jatropha gossypifolia has been known to thrive well in tropical climate, most importantly in Nigeria where they are found to grow naturally on dumpsites. The potential use of this robust tropical plant in phytoremediation technology should be advocated especially for developing countries. This study investigates the effect of enhanced phytoextraction on the accumulation of the following heavy metals; (Cd, Cr, Fe, Mn, Pb, Zn, Ni, Cu, Co and Sn) by J. gossypifolia cultivated on soil collected from dumpsites in Ekiti state, South Western Nigeria, with application of 1g/kg EDTA (Experiment) and without (control). Application of 1g/kg EDTA did not adversely affect plant growth, except at preflowering stage where were yellowing of leaves. The concentration of heavy metals in tissues of plant were higher in the experiment than control, with concentration of

The recovery of valuable metals from waste printed circuit boards (WPCBs) is crucial in order to harness their economic resources, and prevents potential environmental contamination. However, selective extraction of Cu and Zn, and the co-extraction of other metals as impurities at ambient temperature using selected lixiviants such as HCl, H2SO4, HNO3, trifluoromethanesulfonic acid (TFMS), NaOH, and mixtures of NaCl and CuCl2 was studied. It is shown that the extraction efficiencies of all the metals increased with increases in lixiviant concentrations. High selectivity of Cu and Zn toward Fe were achieved in dilute H2SO4, HNO3, TFMS, and 0.5 M NaCl + 0.1 M CuCl2, and low dissolution of Pb (<5%) was observed in all H2SO4 lixiviants. Almost 100% Zn extraction using NaOH lixiviants without trace of other metals was achieved. Therefore, 0.5 M NaCl + 0.5 M CuCl2, 1.0 M HNO3, 0.5 M H2SO4, and 1.0 M TFMS showed high extraction selectivity toward Cu and Zn with low chemical consumption, and produced pregnant leach solution rich in Cu and Zn, as well as residue containing Fe, Ni, and other metals.

Abstract. This study investigates the effect of enhanced phytoextraction on the accumulation of heavy metals by Alocasia microrrhiza cultivated on soil collected from selected dumpsites in Ekiti State, Nigeria. The application of 1g/kg EDTA decreased the heights of plants relative to control, but significantly increased the concentration of heavy metals in various tissues of the plant. Notably, concentration of Pb and Cu were greater than the threshold value of 100mg/kg, indicative of the fact that Alocasia microrrhiza could be a good candidate for Pb and Cuphytoextraction. BF, TF and RR values (1.1-1.6), (4.3-4.8) and (1.4-2.3) revealed the effectiveness of the plant to translocate Pb and Cu to their harvestable portion. RRs values greater than one also indicated the efficiency of plant under chelate-induced phytoextraction. However, the concentration of heavy metals did not vary significantly at p < 0.05 (LSD test) in all dumpsites investigated.

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