title: Removal of aqueous manganese using the natural zeolitic tuff from the Vranjska Banja deposit in Serbia.
abstract: The natural zeolite tuff from the Vranjska Banja deposit (Serbia) has been studied as sorbent for Mn(II) ions from aqueous solutions. The zeolite sample containing mainly clinoptilolite (more than 70%) removes Mn(II) ions by ion-exchange process, which was confirmed by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDXS). XPS showed that there is no surface accumulation of Mn but an almost uniform distribution inside the sorbent; EDXS confirmed that Mn(II) replaced the clinoptilolite Na counter ions. The sorption isotherms were studied at 298 K by batch experiments showing that the Mn(II) removal is best described by the Langmuir-Freundlich or Sips model. The kinetics followed the pseudo-second-order model, the activation energy being 128 kJ mol(-1). The intra-particle diffusion is not the rate-controlling step in the sorption of Mn(II) on clinoptilolite. Thermodynamic data suggest spontaneity of the endothermic ion-exchange process in the 298-338 K range.
authors.affiliation: Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia. nena@tmf.bg.ac.rs
authors.forename: Nevenka
authors.initials: N
authors.lastname: Rajic
authors.forename: Djordje
authors.initials: D
authors.lastname: Stojakovic
authors.forename: Sanja
authors.initials: S
authors.lastname: Jevtic
authors.forename: Natasa
authors.initials: N
authors.lastname: Zabukovec Logar
authors.forename: Janez
authors.initials: J
authors.lastname: Kovac
authors.forename: Venceslav
authors.initials: V
authors.lastname: Kaucic
mesh_terms: D000327:Adsorption; D007474:Ion Exchange; D007700:Kinetics; D008345:Manganese / Q000302:isolation & purification*; D055771:Serbia; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods; D017641:Zeolites / Q000737:chemistry*
chemical_list: D014874:Water Pollutants, Chemical; D017641:Zeolites; D008345:Manganese