Journal of Hazardous Materials 163 (2009) 58–64 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Biosorption of Pb(II) ions by modified quebracho tannin resin Meral Yurtsever ∗ , ˙ I. Ayhan S ¸ engil Department of Environmental Engineering, Engineering Faculty, Sakarya University, 54187 Sakarya, Turkey article info Article history: Received 23 January 2008 Received in revised form 10 June 2008 Accepted 16 June 2008 Available online 27 June 2008 Keywords: Biosorption Isotherms Kinetics Lead Quebracho tannin resin abstract In this study, the effect of temperature, pH and initial metal concentration on Pb(II) biosorption on mod- ified quebracho tannin resin (QTR) was investigated. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to investigate QTR structure and morphology. Besides, the specific BET surface area and zeta-potential of the QTR were analysed. Thermodynamic functions, the change of free energy (G ◦ ), enthalpy (H ◦ ) and entropy (S ◦ ) of Pb adsorption on modified tannin resin were calculated as -5.43 kJ mol -1 (at 296 ± 2 K), 31.84 kJ mol -1 and 0.127 J mmol -1 K -1 , respectively, indicating the spontaneous, endothermic and the increased randomness nature of Pb 2+ adsorption. The kinetic data was tested using pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffu- sion model. The results suggested that the pseudo-second-order model (R 2 > 0.999) was the best choice among all the kinetic models to describe the adsorption behavior of Pb(II) onto QTR. Langmuir, Freundlich and Tempkin adsorption models were used to represent the equilibrium data. The best interpretation for the experimental data was given by the Langmuir isotherm and the maximum adsorption capacity (86.207 mg g -1 ) of Pb(II) was obtained at pH 5 and 296 K. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Heavy metal ions such as Pb, Cd, Hg, Cr, Ni, Zn and Cu are non-biodegradable, can be toxic and carcinogenic even at very low concentrations, and, hence, usually pose a serious threat to the environmental and public health [1]. Due to industrial activ- ity and technological development, releases of Pb(II) metal ions to the environment are on the rise. They pose a significant threat to the environment and public health because of toxicity, incremental accumulation in the food chain and persistence in the ecosys- tem [2,3]. Lead is extremely toxic, which makes it a hazardous environmental pollutant [4]. This pollutant is introduced into nat- ural waters by a variety of industrial wastewaters including those from battery, paper and pulp, mining, electroplating, lead smelting and metallurgical finishing, dyeing, storage-battery and automotive industries. It directly enters the water bodies through the effluent discharges and causes a marked increase in concentrations [5,6]. When accumulated at high levels, lead can generate serious health problems. Lead poisoning causes damage to liver, kidney and reduc- tion in hemoglobin formation, mental retardation, infertility and abnormalities in pregnant women [7,8]. Among the techniques employed for the treatment of heavy metals are chemical precipitation, adsorption, electrolytic methods, ion-exchange, solvent extraction, chemical oxidation or reduction, ∗ Corresponding author. Tel.: +90 264 2955643; fax: +90 264 2955601. E-mail address: mevci@sakarya.edu.tr (M. Yurtsever). filtration, membrane systems and reverse osmosis [9,10]. However, these methods require high capital investment as well as creat- ing sludge disposal problem [11]. Most of the recent studies to remove heavy metals from aqueous solutions focus on the produc- tion of much more effective low-cost adsorbents through naturally occurring materials [12]. Many researchers suggest a cost effec- tive process, such as biosorption, for removing heavy metals from wastewaters [13]. Biosorption, a biological method of environmen- tal control can be an alternative to conventional waste-treatment facilities [10]. The concept of biosorption refers to the passive sorp- tion and/or complexation of metal ions by biomass [14]. Mohanty et al. argue that a wide range of non-living biomass like bark, lignin, peanut hulls as well as living biomass like fungi, bacteria, yeast, moss, aquatic plants and algae has been used as biosorbents [15]. To remove some heavy metals there are other studies in which var- ious waste biomaterial sources in different parts of the world are used as adsorbent. For instance; tea waste adsorbent (for Cu and Pb) [6], pectin compounds (for Pb) [2], lichen (Cladonia furcata) biomass (for Pb and Ni) [16], diethylenetriamine functionalized polymeric adsorbent (for Cu and Pb) [1], crab and arca shell biomass (for Cu and Pb) [17], olive stone waste (for Cu, Pb, Cd and Ni) [18], tamarind wood activated carbon (for Pb) [7], treated sawdust (Acacia arabica) (for Cr(VI), Cu and Pb) [19], anaerobic granular biomass (for Cu, Pb, Cd and Ni) [13], formaldehyde polymerized banana stem (for Pb) [5], Cassia grandis seed gum-graft-poly(methylmethacrylate) (for Pb) [8]. Several studies have been proposed in the literature about the use of modified tannin resins, in relation with heavy metal biosorption from water (Table 1). In the last decade, researches 0304-3894/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2008.06.077