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 Langm