Adsorptive Elimination of Cu(II) Ions from Aqueous Solution onto Chitosan Modified with Uracil.

The remediation of industrial wastewater to eliminate heavy metal ions represents a pressing environmental requirement. A previously prepared adsorbent, based on chitosan modified with uracil (UCs), was investigated for the first time in this work to eliminate Cu(II) ions. The best conditions for elimination were as follows: adsorbent dose = 0.01 g, Cu(II) ions solution concentration = 0.2 g L⁻¹, pH = 6, and temperature = 25 °C. The adsorption kinetics were favorable for the pseudo second order due to the correlation coefficient's value being the highest (R² = 1.0). The experimental value of q_e (99.65 mg g⁻¹) was comparable to that of the theoretical one (100 mg g⁻¹). The removal efficiency reached 99.65%, and the adsorption isotherm coincided with the Freundlich model, denoting that the nature of its adsorption was multi-layered. Cu(II) ions removal mainly relies on the physisorption phenomenon. The desorption percentages reached 92.65, 75.29, 49.29, and 19.92% after four successive cycles. So, the insertion of nitrogen-rich uracil along the chitosan chains, as binding sites for Cu(II), is deemed to be an outstanding opportunity to produce an appropriate, efficacious adsorbent that is a good choice to apply in the metal removal domains. [ABSTRACT FROM AUTHOR]