Effective Removal of Cu(II) Ions from Aqueous Solution by Cross-Linked Chitosan-Based Hydrogels.

The elimination of metal ions from industrial waste water is one of the most significant environmental needs. For the first time, two chitosan hydrogels that we had previously synthesized, cross-linked with varying concentrations of trimellitic anhydride isothiocyanate (represented by H₁ and H₂), were utilized in this investigation to adsorb Cu(II) ions. We found that pH 6, 25 °C, 200 mg L⁻¹ of Cu(II) ions concentration, and 15 mg of hydrogel dosage were the ideal parameters for Cu(II) ion elimination. The kinetics of their adsorption fitted to the pseudo-second-order model with the highest correlation coefficient (R²) values equal to 0.999 and 1.00 for H₁ and H₂, respectively. The experimental q_e values were found when H₁ was equal to 97.59 mg g⁻¹ (theoretical value is equal to 98.04 mg g⁻¹) and H₂ was equal to 96.20 mg g⁻¹ (theoretical value is equal 99.01 mg g⁻¹). The hydrogels achieved a removal effectiveness of 97.59% and their adsorption isotherms matched the Freundlich model, indicating the multi-layered and homogeneous adsorption nature. The removal of copper ions is significantly driven by the physisorption phenomenon. The hydrogels have a great possibility to be utilized as promising, efficacious, reusable adsorbents for industrial wastewater remediation. Thus, incorporation of a cross-linker, containing binding centers for Cu(II) ions, between chitosan chains is a good way to obtain suitable efficient adsorbents which are good choices for application in the field of metal elimination. [ABSTRACT FROM AUTHOR]