Impregnation of multiwall carbon nanotubes in alginate beads dramatically enhances their adsorptive ability to aqueous methylene blue

In this work, novel environmentally benign nanocomposites, carboxyl functionalized multiwall carbon nanotubes (MWCNT-COOH) impregnated into calcium-alginate (CA) beads (CA-MWCNT-COOH), were tested for their abilities to remove a common dye contaminant, methylene blue (MB), from aqueous solution. Kinetic studies showed that the adsorption process of CA-MWCNT-COOH had similar speed to that of CA beads but was slower than that of undispersed MWCNT-COOH. With a Langmuir maximum MB adsorption capacity of 1189 mg g−1, the CA-MWCNT-COOH performed best, outperforming both CA beads alone (1144.7 mg g−1) and the undispersed MWCNT-COOH (33.4 mg g−1). Furthermore, the impregnation also dramatically enhanced the adsorption of MB onto other types of MWCNTs, indicating CA beads are an excellent supporting material to disperse and stabilize carbon nanotubes for their optimal application as a high-capacity adsorbent.