Use of sodium decanoate for selective precipitation of metals contained in industrial wastewater

• Published in: Chemosphere (Oxford) Vol. 69; no. 5; pp. 763 - 768
• Main Authors: Mauchauffée, Stephanie, Meux, Eric
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.10.2007; Elsevier
• Subjects: Applied sciences; Chemical Precipitation; Decanoic acid; Decanoic Acids - chemistry; Exact sciences and technology; Industrial Waste - analysis; Industrial wastewater; Industrial wastewaters; Metal decanoate; Metals, Heavy - chemistry; Models, Chemical; Pollution; Selective precipitation; Solubility; Wastewaters; Water Purification - methods; Water treatment and pollution; Industrial wastewater; Decanoic acid; Metal decanoate; Selective precipitation; Solubility; Material recovery; Recovery metals; Chemical precipitation; Selectivity; Sewage sludge; Heavy metal; Waste management; Industrial waste water; Upgrading; Waste reuse; Organic salt; Carboxylate; Water solubility; Separation process; Physicochemical purification; Waste water purification
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2007.05.006

Conventional methods for heavy metal removal from industrial wastewater involve a chemical precipitation. This process leads to sludges without any commercial value which are stored in specialized landfills. This paper describes a study on the possibility to perform selective precipitation of binary mixtures of metal cations using sodium decanoate. First, the solubility product of six metal decanoates is determined. These six compounds were prepared and controlled before determining their solubility in pure water at 20 °C. The solubility product K sp obtained for Cd, Cu, Mn, Ni, Pb and Zn decanoates are respectively 10 −11.69, 10 −14.65, 10 −10.16, 10 −9.17, 10 −16.05 and 10 −13.05. Additionally, the selective precipitation of binary mixtures was studied. Using p K sp values above, the solubility domain of each decanoate was established. The six superimposed curves allow prediction of the feasibility of separation. According to these curves, nine separations seem to be possible. In each case, precipitation was experimentally performed. The obtained results verify the reliability of this prediction tool. The feasibility of the selective precipitation of metal cations using sodium decanoate is clearly shown.