Dried sugar beet pulp, an agricultural solid waste by-product, was used as an biosorbent for the removal of copper(II) from aqueous
solution. A series of experiments were conducted in a batch system to assess the effect of the system variables, i.e. initial pH, temperature and
initial metal ion concentration. The results indicated that at 250 mg l1 initial copper(II) concentration dried sugar beet pulp exhibited the
highest copper(II) uptake capacity of 28.5 mg g1 at 25 8C and at an initial pH value of 4.0. The equilibrium data were analyzed using the
Freundlich, Langmuir, Redlich–Peterson and Koble–Corrigan isotherm models depending on temperature. The Langmuir model was found to
best describe the data in the concentration and temperature ranges studied. Simple mass transfer and kinetic models were applied to the
experimental data to examine the mechanisms of biosorption and potential rate-controlling steps such as external mass transfer, intraparticle
diffusion and biosorption process. It was found that the intraparticle diffusion played an important role in the biosorption mechanisms of
copper(II), and biosorption kinetics followed pseudo first- and pseudo second-order kinetic models rather than the saturation type kinetic
model for all temperatures studied. The activation energy of biosorption (EA) was determined as 58.47 kJ mol1 using the Arrhenius
equation. Using the thermodynamic equilibrium coefficients obtained at different temperatures, the thermodynamic constants of biosorption
(DG8, DH8 and DS8) were also evaluated.