Abstract
The biosorption of manganese(II) ions from aqueous solution by glutaraldehyde cross-linked chitosan (GCC) was studied under equilibrium conditions. The biosorbent was characterised by FT-IR spectroscopy and scanning electron microscopy (SEM) methods. The effects of the variable experimental parameters such as pH, metal ion concentration, adsorbent amount, contact time and temperature on the adsorption process were investigated. The equilibrium adsorption data were interpreted via the Freundlich, Langmuir and Sips isotherm models. Based on the error function values, the kinetic data were fitted to a better extent by the pseudo-second-order kinetic model and the chemisorption model, relative to the pseudo-first-order, fractional order and Weber-Morris models. The monolayer adsorption capacity of GCC as obtained from the Langmuir isotherm at 25 degrees C was found to be 278 mg/g. Thermodynamic studies indicated that the adsorption process was spontaneous (Delta G(0) < 0) and exothermic (Delta H-0 < 0).