Adsorption of Copper by Raw Pinecone

This work was carried out in order to study the possibility of using pinecones as inexpensive sorbent material for the removal of copper ions in solution. The experiment was carried out in the Department of Chemistry, University of Ibadan, Ibadan, Oyo State, Nigeria. Batch adsorption studies were conducted to determine the optimum conditions for adsorption of copper ions on pinecone. 20mL of the aqueous metal ion solution was agitated with 1g of the adsorbent and different parameters varied. Langmuir and Freundlich isotherm models were used to analyse the experimental data. Equilibrium data fitted well the Langmuir model (R2=0.988). The monolayer adsorption capacity of Cu2+ was found to be 38.46mg/g. The Lagergren’s pseudo first order and pseudo second order kinetic models were selected to study the adsorption process. Kinetic data was found to show very good fit with the pseudo second order kinetic model (R2 = 1). This shows that the adsorption of copper can be described by the pseudo second order equation, showing that the adsorption process is chemisorption between the metal ions and pinecone. The thermodynamic parameters ∆G, ∆H and ∆S were calculated for predicting the nature of adsorption. The negative value of the calculated Gibbs free energy value obtained for the sorption of Cu2+ on raw pinecone shows the adsorption to be spontaneous and feasible.

The results show that pinecone can be used as a low-cost and effective adsorbent for removal of heavy metal ions from aqueous solutions.