Some Thermodynamic Data on Copper-Chitin and Copper-Chitosan Biopolymer Interactions

Area of Science:

• Environmental Science
• Materials Science
• Physical Chemistry

Background:

• Chitin and chitosan are natural biopolymers with cation removal capabilities.
• Wastewater treatment often requires efficient methods for heavy metal ion removal.

Purpose of the Study:

• To investigate the interaction between copper cations and chitin/chitosan in aqueous solutions.
• To quantify the thermodynamic parameters of copper ion complexation with these biopolymers.

Main Methods:

• Batch adsorption studies at 298 K.
• Calorimetric titration using copper nitrate solution.
• Adsorption isotherm analysis using a modified Langmuir equation.

Main Results:

• The interaction was spontaneous, with negative Gibbs free energy (ΔG) values.
• Enthalpic (ΔH) values indicated exothermic complexation: -19.85 kJ/mol for chitin and -41.27 kJ/mol for chitosan.
• Entropy (ΔS) values varied, suggesting complexation mechanisms involving polymer chain disorder or water molecule release.

Conclusions:

• Chitin and chitosan form stable complexes with copper ions, likely through coordination with pendant groups.
• The thermodynamic data supports the use of these biopolymers for copper removal from aqueous environments.
• The observed complexation mechanisms highlight the versatility of chitin and chitosan in environmental remediation.