Alkali modified Abies bornmulleriana cones as a costeffective biosorbent for enhanced removal of Pb (II) ions, and its comparison with normal biosorbent: Isotherm, kinetic, and thermodynamic parameters

The purpose of this investigation is the increase the biosorption efficiency and capacity in the removal of Pb (II) ions using Abies bornmulleriana cones modified with NaOH. The biosorption capacity of Pb (II) ions decreased in the presence of Cu (II), Cd (II), Ni (II), and Co (II) ions. Brunauer, Emmett, and Teller surface area and pore volume of the NB and MB after the biosorption decreased by (4.37 m(2) g(-1) and 0.00154 cm(3) g(-1)) and (0.41 m(2) g(-1) and 0.00014 cm(3) g(-1)), respectively. The pseudo-second-order kinetic gave the best fit to the biosorption data (R-2 0.97, 0.97). The biosorption data for the NB and MB fitted well to Dubinin-Radushkevitch (D-R) isotherm due to the high R-2 values (0.97, 0.97), and the maximum biosorption capacities were determined as 24.42 and 43.67 mg g(-1), respectively. The change of free energy, enthalpy, and entropy of the biosorption for the NB and MB were determined as [(-2.10 kJ mol(-1), 14.72 kJ mol(-1), and 0.057 kJ mol(-1) K-1) and (-7.04 kJ mol(-1), 121 kJ mol(-1), and 0.438 kJ mol(-1) K-1)], respectively. The NB and MB regeneration with 0.1 N HNO3 showed that the biosorption and desorption processes were reversible.