Thermodynamic aspects of sorption of Fe2+ onto unbleached kraft fibres

The sorption of Fe2+ onto unbleached kraft fibre was investigated at different conditions such as pH, temperature, and concentrations. The sorption, which increased with concentration and temperature, followed the Langmuir isotherm. Thermodynamically, the process was spontaneous and endothermic. It was found that the precipitation of Fe2+ was highly dependent on pH and reached 100% when pH exceeded ∼8.

The sorption of Fe2+ increased when pH >3 due to the increased degree of ionization of the cellulosic components in the fibres. When pH exceeded 8, 100% of Fe2+ precipitated in the solution.Figure optionsDownload as PowerPoint slide