Removal of metal ions from a petrochemical wastewater using brown macro-algae as natural cation-exchangers

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 286; pp. 1 - 15
• Main Authors: Cechinel, Maria A.P., Mayer, Diego A., Pozdniakova, Tatiana A., Mazur, Luciana P., Boaventura, Rui A.R., de Souza, Antônio Augusto U., de Souza, Selene M.A. Guelli U., Vilar, Vítor J.P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-02-2016
• Subjects: Fixed-bed column; Macro-algae; Multi-metal systems; Natural cation exchanger; Petrochemical wastewater; Multi-metal systems; Fixed-bed column; Macro-algae; Petrochemical wastewater; Natural cation exchanger
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2015.10.042

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•Heavy metals removal from petrochemical wastewater (PW) by ion-exchange.•Brown marine macro-algae as natural cation exchanger for PW treatment.•Trapping of heavy metals by raw biomass occurs by the release of light metals.•L. hyperborea showed an useful capacity of 1558, 515 and 528 BV for Cu, Zn and Ni.•Desorption using 1.2% HCl eluent (11 BV) was fast and near 100% effective.
Four brown macro-algae, Ascophyllum nodosum, Fucus spiralis, Laminaria hyperborea and Pelvetia canaliculata, were investigated as natural cation exchangers for the removal of transition metals from a petrochemical wastewater. The wastewater presents a high conductivity due to chloride, sulfate, sodium, calcium and residual concentrations of copper, zinc and nickel species. According to all-inorganic species evaluated, the molar fraction of Zn2+, Cu2+ and Ni2+ is near 92% and the remaining species are ZnCl+, ZnSO4, CuSO4, NiCl+ and NiSO4. A Langmuir multicomponent model was able to predict the ion-exchange equilibrium data for Cu, Ni, Zn and Ca species present in the petrochemical wastewater. L. hyperborea showed a higher uptake capacity than the other brown algae tested. The equilibrium affinity constants for the functional groups decreased in the following order: Cu>Zn>Ni≈Ca, except for L. hyperborea, which presents a lesser affinity for Ca. Ion-exchange breakthrough curves obtained from a fixed-bed column packed with raw L.hyperborea, led to an operating capacity of 0.22, 0.10 and 0.05mEq/g for Cu, Zn and Ni, corresponding to 1558, 515, 528BV (7.2BV/h), respectively. The treatment strategy consisted in the operation of two consecutive columns, the first one for copper ions removal (operating capacity of 1558 BV – 7.2 BV/h) and the second one for zinc and nickel removal (operating capacity of 163BV–7.3BV/h). The elution of Cu, Zn and Ni from the natural resin was achieved with 10 and 6BV of HCl (0.4M, 1.2%) (150 and 90g HCl/L of resin), using a flow rate of 3.6BV/h, respectively for the first and second columns.