Kinetic study on removal of copper(II) using goethite and hematite nano-photocatalysts

Goethite and hematite nanomaterials (nano-goethite and nano-hematite) can be synthesized using a coprecipitation method. Nano-hematite is synthesized via the reaction of HCl and FeCl3 solution at 100 degrees C for 2 days, while nano-goethite is prepared by adding Fe-2(SO4)(3) into the 2.5 M NaOH solution for 4 h, and then heated at 40 degrees C for 2 days. Afterward the photocatalytic decomposition of methylene blue solution is performed by UV-light irradiation, and the adsorption procedure is carried out by batch experiments. It is observed that both nano-hematite and nano-goethite exhibit some photocatalytic activity and possess a high adsorption capacity for copper ions. The maximum Cu(II) adsorption capacity is 149.25 and 84.46 mg/g for nano-goethite and nano-hematite, respectively. Further, the experimental data are well fitted to the pseudo-second-order equation. It also suggests that the Langmuir isotherm is more adequate than the Freundlich isotherm in simulating the adsorption isotherm of Cu2+, and the Cu2+ adsorption onto nanomaterials is a spontaneous process. Therefore, these findings indicate that nano-goethite and nano-hematite are effective materials for Cu2+ removal and, together with its photocatalytic activity, may be applied in the removal of heavy metal ions from aqueous streams. Crown Copyright (C) 2010 Published by Elsevier Inc. All rights reserved.