title: EDTA modified LDHs as Cu2+ scavengers: removal kinetics and sorbent stability.
abstract: EDTA modified layered double hydroxides (LDHs) were investigated as potential sorbents to remediate heavy metals pollution. The polidentate ligand was introduced by an exchange method in a Zn-Al-LDH, which takes place with partial erosion of the layers, causing the intercalation of [Zn(EDTA)](2-) complex instead of the ligand. [Cu(H(2)O)(6)](2+) cation was selected as a model cation to study the uptake mechanism, exploring the elimination kinetics from the first minutes up to the steady state. A flow injection analysis system coupled to an amperometric detector (FIA-AM) was applied to perform fast and reliable [Cu(H(2)O)(6)](2+) determinations in monodisperse solid-aqueous solution systems. Furthermore, the sorbent stability was determined as a function of the pH and the nitrate concentration. The [Cu(H(2)O)(6)](2+) elimination is produced by an exchange reaction with [Zn(EDTA)](2-) anions placed either in the solid interlayer or in the aqueous solution, this last being released from the sorbent. Additional [Cu(H(2)O)(6)](2+) removal is produced by Cu(OH)(2) precipitation at high copper concentrations due to the LDHs high pH buffering capacity. The sorbent removes [Cu(H(2)O)(6)](2+) with high affinity in a wide concentration range. The elimination process reaches equilibrium in less than 30 min and leaves metal cation concentrations lower than 0.05 ppm in the supernatants.
authors.affiliation: INFQC, Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Rojas
authors.forename: M Rosario
authors.initials: MR
authors.lastname: Perez
authors.forename: Eustaquio M
authors.initials: EM
authors.lastname: Erro
authors.forename: Patricia I
authors.initials: PI
authors.lastname: Ortiz
authors.forename: Maria Angeles
authors.initials: MA
authors.lastname: Ulibarri
authors.forename: Carla E
authors.initials: CE
authors.lastname: Giacomelli