title: Electrochemical EDTA recycling after soil washing of Pb, Zn and Cd contaminated soil.
abstract: Recycling of chelant decreases the cost of EDTA-based soil washing. Current methods, however, are not effective when the spent soil washing solution contains more than one contaminating metal. In this study, we applied electrochemical treatment of the washing solution obtained after EDTA extraction of Pb, Zn and Cd contaminated soil. A sacrificial Al anode and stainless steel cathode in a conventional electrolytic cell at pH 10 efficiently removed Pb from the solution. The method efficiency, specific electricity and Al consumption were significantly higher for solutions with a higher initial metal concentration. Partial replacement of NaCl with KNO(3) as an electrolyte (aggressive Cl(-) are required to prevent passivisation of the Al anode) prevented EDTA degradation during the electrolysis. The addition of FeCl(3) to the acidified washing solution prior to electrolysis improved Zn removal. Using the novel method 98, 73 and 66% of Pb, Zn and Cd, respectively, were removed, while 88% of EDTA was preserved in the treated washing solution. The recycled EDTA retained 86, 84 and 85% of Pb, Zn and Cd extraction potential from contaminated soil, respectively.
authors.affiliation: Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
authors.forename: Maja
authors.initials: M
authors.lastname: Pociecha
authors.forename: Damijana
authors.initials: D
authors.lastname: Kastelec
authors.forename: Domen
authors.initials: D
authors.lastname: Lestan
mesh_terms: D002104:Cadmium / Q000737:chemistry / Q000302:isolation & purification*; D004492:Edetic Acid / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D007854:Lead / Q000737:chemistry / Q000302:isolation & purification*; D012989:Soil Pollutants / Q000737:chemistry / Q000302:isolation & purification*; D015032:Zinc / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D012989:Soil Pollutants; D002104:Cadmium; D007854:Lead; D004492:Edetic Acid; D015032:Zinc