Monday, April 29, 2013
Exhibit Hall
Although 70% of the surface of our planet is covered with water, less than 3% is freshwater, that 65% is suitable for human direct consumption. The shortage of this precious liquid is real in several regions of the world. In recent years, the chelating agents have been extensively investigated due to their behavior as sequestrant agent of metal ions present in aqueous solutions. Among the substances that have a high chelating capacity, lignin highlights because of the presence in its structure of coordinating atoms with metal ions. The objective of the present work was to study the interaction between the cane straw lignin and Cu2+ ions in ammonium hydroxide medium. To this propose, solutions were prepared containing lignin(0.01 g.L-1), ammonium hydroxide and Cu2+, varying the ammonia concentrations in the reaction medium from 2 to 5% (v/v), Cu2+ from 0.004 mol.L-1 to 0.010 mol.L-1. Ammonium hydroxide was chosen because it solubilizes lignin and forms a soluble complex with copper, thus facilitating interaction with the lignin. All solutions were analyzed in spectrophotometer at 200 to 800 nm region. The results showed that the hydroxide is suitable for this test, because Cu2+ ions were completely solubilized. It was also verified that lower amount of hydroxide studied (2% v/v) is enough for the total dissolution of the metal ion. The interaction between lignin and Cu2+ was low, but caused shift in UV absorption. Because of this, a deeper study of this interaction is being carried out [Acknowledgments due to CNPq].