Removal of heavy metals from a contaminated soil using organic chelating acids

Abstract

Changes in heavy metal speciation and uptake by maize in a soil before and after washing with chelating organic acids, citric acid, tartaric acid and ethylenediaminetetraacetic acid were assessed. A sandy loam was collected from the vicinity of the Benue industrial layout, Makurdi, Nigeria and spiked with a quinternary mixture of nickel, copper, zinc, cadmium and lead nitrates to achieve higher levels of contamination. Batch soil washing experiments performed on 1.0 g portions of the spiked soil using 0.05 M chelating agents at a solid:liquid ratio of 1:25 showed that washing efficiencies varied in the order: ethylenediaminetetraacetic acid> citric acid> tartaric acid with metal extraction yields typically following the sequence, copper> nickel> zinc> cadmium> lead. Sequential extractions proposed by the European Communities Bureau of Reference method used to assess the redistribution of heavy metal forms in the soil showed that apparent metal mobilities were reduced upon soil washing. Citric acid removed most of the metals hitherto associated with the exchangeable and reducible fractions; tartaric acid, the exchangeable metal pools; and ethylenediaminetetraacetic acid, the non-residual metal pools. Heavy metal assay of harvested biomass of maize grown on unwashed and washed soil samples indicated that metal transfer coefficients, decreased in the order of treatment: ethylenediaminetetraacetic acid <citric acid <tartaric acid <unwashed soil. Ethylenediaminetetraacetic acid and citric acid appeared to offer greater potentials as chelating agents to use in remediating the high permeability soil. Tartaric acid, however, is recommended in events of moderate contamination.

Biotechnological advances in bioremediation of heavy metals contaminated ecosystems: an overview with special reference to phytoremediation

“…The remediation can be attempted through conventional remedial measures such as land filling and leaching, excavation and burial or soil washing (Wuana et al 2010;Vesely et al 2012). An extensive use of solidwaste landfills for disposal of municipal and industrial wastes as well as inappropriate use of agro-chemicals has generated a huge amount of leachate causing groundwater pollution (Nouri et al 2008), and the potential for groundwater contamination by leachate has necessitated for the invention of novel engineering designs for landfills (Sivakumar 2012).…”

Interaction of organic acids and pH on multi-heavy metal extraction from alkaline and acid mine soils

“…Schwab et al (2008) found that citric acid greatly enhanced the movement of Zn and Cd in soils, but had little influence on Pb movement. And some researchers also found that citrate had the most efficiency in releasing Cd, Pb and Zn than other organic acids (Wuana et al 2010;Vesely et al 2011). Low concentration of tartrate and citrate inhibited the desorption of Cd and Cu, but high concentration of tartrate and citrate promoted the desorption (Gao et al 2003).…”

Hexavalent chromium removal from aqueous solutions by using low-cost biological wastes: equilibrium and kinetic studies

“…Different types of biosorbents have been investigated for the removal of heavy metals from aqueous solutions (Abdel-Ghani and El-Chaghaby 2007; Okoye et al 2010;Wuana et al 2010;Zavvar Mousavi and Seyedi 2011;Gueu et al 2007). Among many biosorbents naturally available, plant biomass can be used as an inexpensive biosorbent for removal of metal ions from synthetic solutions and industrial effluents (Manal 2007).…”