Kinetic Rate Equations Application on the Removal of Copper (II) and Zinc (II) by Unmodified Lignocellulosic Fibrous Layer of Palm Tree Trunk- Single Component System Studies

The kinetics of biosorption of Zinc and copper using unmodified lignocellulosic fibrous layer of palm tree trunk was investigated. Batch adsorption technique was employed for the metal ions biosorption in a single component system. The amount of metal ions biosorped increased with time. Zinc was more rapidly removed but the highest sorption rates for the metal ions were 79.7% for Cu2+, and 78.05% for Zn2+. The fractional attainment of equilibrium showed that Zn2+ reached equilibrium before Cu2+. The biosorption process for the metals used was selective to be in the order Cu (II) > Zn (II). Six kinetic rate equations applied to the data include First-order, Second-order, Pseudo first-order, Pseudo second-order, Elovich equation and the intra-particle diffusion equation. The rate equations applied gave good fit to experimental data for Cu2+ as shown by the regression coefficients R2 > 0.9. For Zn2+, only pseudo-second order kinetic model could explain the experimental kinetic data with regression coefficient R2 = 0.992. The biosorption process was found to follow the physisorption and chemisorptions mechanism for Cu2+ and chemisorptions for Zn2+. This experiment shows that unmodified lignocellulosic fibrous layer of palm tree trunk can be effectively utilized for Cu2+ and Zn2+ removal from diluted solutions