Journal of Hazardous Materials 166 (2009) 1449–1458 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Preconcentration of Zn(II) in water samples using a new hybrid SBA-15-based material Damián Pérez-Quintanilla, Alfredo Sánchez, Isabel del Hierro, Mariano Fajardo, Isabel Sierra ∗ Departamento de Química Inorgánica y Analítica, E.S.C.E.T, Universidad Rey Juan Carlos, C/Tulipán s/n, 28933 Móstoles, Madrid, Spain article info Article history: Received 11 November 2008 Received in revised form 11 December 2008 Accepted 12 December 2008 Available online 24 December 2008 Keywords: Heavy metal adsorption SBA-15 Preconcentration Zinc Hybrid materials abstract A SBA-15 mesoporous silica has been chemically modified with 5-mercapto-1-methyltetrazole. The newly synthesized material (MTTZ-SBA-15) has been characterized, by powder X-ray diffraction, N 2 adsorption, FT-IR, 13 C NMR spectroscopy and elemental analysis, and used to preconcentrate Zn(II) in water samples. The effect of some variables on the adsorption capacity has been studied using the column techniques. The adsorption capacity of the prepared material followed the order: Zn ≫ Cu > Cd ≫ Mn, and under opti- mized conditions the maximum adsorption value for Zn(II) was 0.96 ± 0.01 mmol/g with the adsorption efficiency of 0.76. In column experiments, adsorption was quantitative for 1000mL of 7.65 × 10 -4 mM of Zn(II) solution and adsorbed ions were eluted out by 5 mL of 1 M HCl (preconcentration factor of 200). Spiked tap water and mineral water were used for the preconcentration and determination of Zn(II) by flame atomic absorption spectrometry (FAAS), and a 102 ± 2 and 98 ± 3% recoveries were obtained. The LOD and LOQ values of the proposed method were found to be 8.0 × 10 -6 and 1.23 × 10 -5 mM, respec- tively. The relative standard deviation for four preconcentration experiments was found to be ≤4% in all cases. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Zinc is present in the air, soil, water and almost all foods. Although it is naturally released into the environment, industrial activities are mostly responsible for zinc pollution (mining and foundry, metal cleaning, steel production, carbon combustion, solid waste incineration, etc.) [1]. In addition, various zinc salts are used industrially in wood preservatives, catalyst, photographic paper, accelerators for rubber vulcanisation, fertilizers, ceramics, textiles, pigments and batteries [1]. Acute exposure to Zn(II) causes health problems such as stomach cramps, skin irritations, vomiting, nau- sea and anaemia. Very high levels of zinc can damage the pancreas, disturb the protein metabolism and cause arteriosclerosis [2]. The presence of heavy metals in the environment is of seri- ous concern as the number of ecological and health problems associated with them is very high [3,4]. Consequently, a great atten- tion has been paid in the last years to determine and/or remove these contaminants from aqueous systems. Adsorption onto solid materials (activated carbon, silica, clays, zeolites and ion-exchange resins) is a valuable technique for separation, preconcentration and/or elimination of heavy metals ions from these samples [5–16]. However, these materials are non-specific adsorbents and suffer from inherent problems, like low removal capacity, low selectiv- ∗ Corresponding author. Tel.: +34 914887018; fax: +34 914888143. E-mail address: isabel.sierra@urjc.es (I. Sierra). ity, long equilibrium time or mechanical and thermal instability. In order to circumvent these limitations, some promising adsorbents have been prepared by functionalization of novel inorganic sup- ports (mesoporous silicas) with organics groups. These materials have recently gained recognition as the most exceptional adsor- bents for heavy metal ion trapping [17–26]. The adsorption capacity and selectivity of hybrid mesoporous silica-based materials mainly depends on the structure of the immobilized organic ligand, the nature of the incorporated donor atoms (O, N, S and P), the position- ing of the functional groups along the surface of the silica support, the steric requirements of the complex formed after uptake of the desired metal ion and the characteristics of the silica support (struc- ture, surface area, pore size and shape, etc.). Obviously, changing the organic ligand and the solid support it is possible to prepare the rationally designed materials with great adsorption capacity and selectivity. Recently, some studies have been carried out to prepare hybrid mesoporous silica-based materials to remove Zn(II) in aqueous media [26–28]. The Zn(II) adsorption capacity of these materi- als ranged from 0.0011 to 1.59mmol/g. Hossain and Mercier [27] obtained a very low zinc loading (1.1 mol/g) with functionalized HMS mesoporous silica prepared by the inclusion of the binding sites inside the framework walls of the material. Jiang et al. [28] reported the competitive removal of Cr 3+ , Cu 2+ , Pb 2+ and Zn 2+ by SBA-15 functionalized with polyamidoamine dendrimers (PAMAM- SBA-15) and EDTA modified PAMAM-SBA-15. In 2008, Yang et al. [26] synthesized a mesoporous adsorbent in ethanol, via the 0304-3894/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2008.12.065