Adsorption of Copper by Biochar

Aims: To study the possibility of using biochar as an inexpensive sorbent material for the removal of copper ions in aqueous solution.

Place of Study: Department of Chemistry, University of Ibadan, Ibadan, Oyo State, Nigeria.

Methodology and Results: Batch adsorption studies were conducted to determine the optimum conditions for adsorption. The biochar was prepared by pyrolysis of pinecones in a furnace at 573K. To create an inert environment, nitrogen gas was introduced into the furnace. The biochar produced was treated with 1M HCl to demineralise it and the slurry separated by vacuum filtration. The residue was washed several times with distilled water and oven dried at 378K. Langmuir and Freundlich isotherm models were used to analyse the experimental data. Equilibrium data fitted well the Langmuir model (R2=0.961). The monolayer adsorption capacity of Cu2+ on the biochar was found to be 8.85mg/g. Kinetic data was found to show very good fit with the pseudo second order kinetic model. The thermodynamic parameters such as ∆G, ∆H and ∆S were calculated for predicting the nature of adsorption and this showed the adsorption to be exothermic.

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