Journal of Hazardous Materials 166 (2009) 74–78 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Research article Removal of chromium Cr(VI) by low-cost chemically activated carbon materials from water Zhongren Yue a,b,∗ , Samantha E. Bender a , Jinwen Wang a , James Economy a,∗∗ a Department of Materials Science & Engineering, University of Illinois at Urbana-Champaign, 1304 W Green St., Urbana, IL 61801, United States b The University of Tennessee Space Institute, 411 B. H. Goethert Parkway Tullahoma, TN 37388, United States article info Article history: Received 25 June 2008 Received in revised form 30 October 2008 Accepted 31 October 2008 Available online 11 November 2008 Keywords: Chromium (VI) removal Activated carbon Porous materials Chemical activation abstract Low-cost, chemically activated carbon materials, Pellet-600 and PVA-300, were prepared at relatively low temperatures and show more effective removal efficiency of Cr(VI) from water than commercially available activated carbons tested. The Pellet-600 is a pelletized carbon material with high mesoporous volumes and surface area, and the PVA-300 is composed of a high surface area carbon coating on a fiberglass mat substrate. A much faster adsorption kinetics and a much higher adsorption capacity for Cr(VI) are achieved by the Pellet-600. At very low concentrations of Cr(VI), the PVA-300 displays a strong adsorption ability for Cr(VI). XPS data show an increase in the atomic ratio of Cr/C and oxidation of carbon materials after adsorption of Cr(VI). These results suggest that a high content of mesopores with a high surface area and surface functional groups greatly improve the Cr(VI) removal efficiency from water. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Chromium (Cr) compounds are widely used in industry such as electroplating, metal finishing, leather tanning, pigments, etc. The predominant use of chromium in industry unfortunately intro- duces an environmental concern. Cr exists almost exclusively in the Cr(III) oxidation state or in the Cr(VI) oxidation state. In the environ- ment Cr(III) is typically not a problem, its relative toxicity is low. In contrast, Cr(VI) compounds are toxic chemicals and genotoxic car- cinogens [1]. Thus, the presence of Cr(VI) ions in the environment is posing serious problems and causing great public concern [2,3]. Currently, the United States Environmental Protection Agency (US EPA) has set a Maximum Contaminant Level (MCL) for chromium at 0.1 parts per million (ppm) in drinking water [4]. The increasing concern with Cr(VI) pollution, significantly motivates the investi- gation and development of new and improved materials to address the problems. A wide range of technologies have been investigated for the removal of Cr(VI) from water [5–11]. Adsorption using activated carbons proved to be the most efficient technique [7–11]. To fur- ther improve the removal efficiency of Cr(VI) ion from water, the ∗ Corresponding author at: The University of Tennessee Space Institute, 411 B. H. Goethert Parkway Tullahoma, TN 37388, United States. Tel.: +1 931 393 7362; fax: +1 931 393 7530. ∗∗ Corresponding author. Tel.: +1 217 333 9260; fax: +1 217 333 2736. E-mail addresses: zyue@utsi.edu (Z. Yue), jeconomy@uiuc.edu (J. Economy). commercially available activated carbons were chemically modi- fied with acid and different oxidizing agents such as HNO 3 ,H 2 O 2 and Fe(NO 3 ) 3 [7,8]. It was found that the adsorption mechanism and rate of Cr(VI) are affected by the modified pore structure and surface properties of the activated carbons. A family of chemically activated carbon materials has been developed by a new approach in our laboratory [12]. This new method provides the carbon materials with relatively low-cost, high surface area, high mesopore volumes, and some unusual pore surface chemistries [13–17]. Some of these activated carbon materials, without any post-chemical treatments, contain high con- centration of functional groups. In most cases, these groups include –OH, O, and –COOH. Some other groups such as >P(O)OH and –P(O)(OH) 2 may exist on the activated materials made from certain raw materials and H 3 PO 4 activation [16]. The previous studies have shown that those kinds of materials have improved removal effi- ciency for trace toxic organics over the granular activated carbons (GACs) [17–20]. Therefore, the novel activated carbon materials with tailored porosity and surface chemistry are expected to have great potential as highly effective adsorbents for removal of Cr(VI) from water. In this work, two chemically activated carbon materials with highly mesoporous volumes and functional groups were prepared and then tested in comparison to standard activated carbons for Cr(VI) removal. The Cr(VI) adsorption kinetics and adsorption isotherms were performed to demonstrate the superior activity of the new materials. The effect of porous and chemical structures on the adsorption of Cr(VI) was also elucidated. 0304-3894/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2008.10.125