Fast adsorption of methylene blue on polyacrylic acid-bound iron oxide magnetic nanoparticles

The adsorption of methylene blue (MB) from an aqueous solution by polyacrylic acid-bound iron oxide magnetic nanoparticles was studied. It was shown that the novel magnetic nano-adsorbent was quite efficient for the adsorption/desorption of NIB. In the aqueous solution of MB at 25 degreesC, the adsorption data could be fitted by the Langmuir equation with a maximum adsorption amount of 0.199 mg/mg and a Langmuir adsorption equilibrium constant of 10.1 ml/mg. The adsorption capacity increased with the increase in solution pH (2-10) and the adsorption process was endothermic in nature with an enthalpy change (DeltaH) of 30.9 kJ/mol at 10-40 degreesC. By using the methanol solution of acetic acid, the adsorbed MB could be desorbed. In addition, it was notable that both the adsorption and desorption of MB were quite fast and could be completed within 2 min due to the absence of internal diffusion resistance. (C) 2003 Elsevier Ltd. All rights reserved.