Nanoparticulate Zeolitic Tuff for Immobilizing Heavy Metals in Soil: Preparation and Characterization Ayoup M. Ghrair & Joachim Ingwersen & Thilo Streck Received: 1 August 2008 / Accepted: 26 January 2009 / Published online: 13 February 2009 # Springer Science + Business Media B.V. 2009 Abstract Nanoparticles derived from natural materials are promising compounds in the field of environmental remediation. The present study produces and character- izes Na-zeolitic tuff in the nanorange, stabilizes the nanotuff in suspension, and investigates the effect of Na-zeolitic nanotuff on sorption of Cd. Breakdown of raw zeolitic tuff with a mean particle size of 109 μm to the nanorange was achieved by attrition milling. In the first stage of grinding, a mixture of Al-oxide beads of 1 to 2.6 mm diameter was used. The milling process lasted 4 h. In the second stage, the dried powder was milled again using a mixture of a fine zirconia beads (0.1 mm) and Al-oxide beads (1.0 mm). The powder was treated with 1 M NaCl solution. Finally, the powder was sonicated in water. After this procedure, the mean and median particle diameters were 47.6 and 41.8 nm, respectively. The nanoparticulate zeolitic tuff had a surface area of 82 m 2 g -1 . The estimated zero charge point of the nanoparticle suspension was 3.2. The surface zeta potential was pH dependent. The Na- zeolitic nanotuff increased Cd sorption by a factor of up to 3 compared to the raw zeolitic tuff. Our results indicate that zeolitic nanoparticles can be produced by grinding using a mixture of fine beads in an attrition mill and that this procedure increases their metal immobilizing potential. Keywords Nanoparticles . Zeolitic nanotuff . Surface area . Attrition mill . Heavy metals . Sorption . Zeta potential 1 Introduction Heavy metal contamination of soil is a key concern because of its toxicity, which threatens human life and the environment (Bhogal et al. 2003; Carmichael 1994; Purves 1985). Cadmium (Cd) is of particular interest because it is one of the most bioavailable and mobile heavy metals in soil and the environment. Cadmium is a highly toxic element that is not known to be essential for any type of organism (McBirde 1994). Cd is easily absorbed by roots and transported to shoots. It is then uniformly distributed in plant organs (Sekara et al. 2005). Uptake of Cd by plants depends on several plant and soil factors such as solution-phase concentration, pH, and organic carbon content. Moreover, the environmental conditions (temperature and saturation deficit) may play an important role in controlling Cd uptake (Ingwersen and Streck 2005). Anthropogenic contamination of soils by heavy metals (Cd, Pb, and Zn) occurs from many sources such as mining, atmospheric deposition Water Air Soil Pollut (2009) 203:155–168 DOI 10.1007/s11270-009-9999-6 A. M. Ghrair (*) : J. Ingwersen : T. Streck Biogeophysics Section, Institute of Soil Science and Land Evaluation, University of Hohenheim, Emil-Wolff-Str. 27, 70593 Stuttgart, Germany e-mail: ghrair@uni-hohenheim.de