Acta Phys. -Chim. Sin. ›› 2006, Vol. 22 ›› Issue (12): 1542-1546.doi: 10.3866/PKU.WHXB20061221

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Adsorption of Hexavalent Chromium Ions on Multi-wall Carbon Nanotubes in Aqueous Solution

QIU Kai-Dong;LI Wei-Bin   

  1. (Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, P. R. China; Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, P. R. China)
  • Received:2006-04-20 Revised:2006-06-05 Published:2006-12-06
  • Contact: LI Wei-Bin E-mail:wbli@mail.tsinghua.edu.cn, wblichem@yahoo.com.cn

Abstract: Carbon nanotubes (CNTs) were employed to remove toxic hexavalent chromium ions from aqueous solution. Effects of concentration of hexavalent chromium, solution pH, coexistent trivalent chromium in the solution on the Cr(VI) adsorption were examined. The results show that the adsorption capacity of Cr(VI) on CNTs increased with increase of Cr(VI) concentration, and then reach a plateau between 300~700 mg•L−1 of Cr(VI); the maximum value of 532.215 mg Cr(VI) per g CNTs was achieved at the Cr(VI) concentration of 493.557 mg•L−1, and followed by a decrease at still higher concentration of Cr(VI). The capacity was also significantly affected by the pH value of the solution between 2 and 7, and little change was observed above pH value of 7. Addition of Cr(III) into the Cr(VI) solution could decrease the Cr (VI) removal capacities because of their competitive adsorption on CNTs. Under the same experimental conditions, CNTs showed an adsorption capacity of Cr(VI) 6 times as large as the commercial activated carbon at 190 mg•L−1 of the concentration of Cr(VI).

Key words: Carbon nanotubes, Adsorption, Cr(VI), Activated carbon