Cellulose derived magnetic mesoporous carbon nanocomposites with enhanced hexavalent chromium removal
Magnetic carbon-iron nanoadsorbents fabricated by carbonizing cellulose and reducing Fe3O4 nanoparticles or Fe(NO3)3 (the products are denoted as MC-O and MC-N, respectively) have demonstrated great Cr(vi) removal. MC-N with a higher proportion of zero-valence iron (ZVI) and bigger specific surface area exhibited better resistance to oxygen and acid than MC-O due to its smaller pore size. The Cr(vi) removal was highly pH-dependent. For example, 4.0 mg L-1 Cr(vi) neutral solution was completely purified by 2.5 g L-1 MC-O and MC-N within 10 min. 1000 mg L-1 Cr(vi) solution at pH 1.0 was completely removed by both nanoadsorbents in 10 min. The MC-O nanoadsorbents had a higher removal percentage (98.1%) than MC-N (93.5%) at pH 7.0, while MC-N had a removal capacity of 327.5 mg g-1, much higher than 293.8 mg g-1 of MC-O at pH 1.0. A chemical adsorption was revealed from the pseudo-second-order kinetic study. Monolayer adsorption of Cr(vi) was revealed by a better fitting of the Langmuir model isotherm, rather than multilayer adsorption for the Freundlich model. These nanoadsorbents could be easily separated from solution by using a permanent magnet after being treated with Cr(vi). Finally, the Cr(vi) removal mechanisms were proposed considering the Cr(vi) reduction and precipitation of Cr(iii).
Publication Source (Journal or Book title)
Journal of Materials Chemistry A
Qiu, B., Gu, H., Yan, X., Guo, J., Wang, Y., Sun, D., Wang, Q., Khan, M., Zhang, X., Weeks, B., Young, D., Guo, Z., & Wei, S. (2014). Cellulose derived magnetic mesoporous carbon nanocomposites with enhanced hexavalent chromium removal. Journal of Materials Chemistry A, 2 (41), 17454-17462. https://doi.org/10.1039/c4ta04040f