Solid-phase extraction of Cu²⁺ and Pb²⁺ from waters using new thermally treated chitosan/polyacrylamide thin films; adsorption kinetics and thermodynamics

<p>New biologically safe thin adsorptive films were synthesised using chitosan/polyacrylamide polymer blend (Ch/PA) via thermal crosslinking technique for the separation of Cu²⁺ and Pb²⁺ from aqueous solution and natural water samples. The prepared films were characterised using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and Thermogravimetric analysis (TGA) techniques. Thermo-gravimetric analysis revealed an enhancement in the thermal stability of the prepared thin films with increasing polyacrylamide content. Kinetic and thermodynamic studies were evaluated by batch-type experiments. The obtained results indicated that the adsorption isotherms were well described by Freundlich model, and Ch/PA have adsorption capacities of 177.9 and 126.58 mg.g⁻¹ to Cu²⁺ and Pb²⁺, respectively. Under optimum conditions, calculated detection limits were as low as 0.018 and 0.034 μg.L⁻¹ for Cu²⁺ and Pb²⁺, respectively, and relative standard deviations of less than 4% for five separate experiments. Moreover, the traditional <i>Lagergren</i> adsorption kinetic model provided the best fitting for the kinetic data. Furthermore, the reusability studies revealed a decrease in the adsorption capacity by about 8% after three adsorption–desorption cycles. The prepared thin films were successfully applied for the separation of Cu²⁺ and Pb²⁺ from natural water samples.</p

Additional file 1 of A novel isatin Schiff based cerium complex: synthesis, characterization, antimicrobial activity and molecular docking studies

Additional file 1: Fig. S1. The FT-IR spectra of Schiff base L2, and Ce(III)-complex C2. Fig. S2. The electronic absorption spectra of Schiff base L2, and Ce(III)-complex C2. Fig. S3. The 1H-NMR spectrum of Schiff base L2. Fig. S4. The 1H-NMR spectrum of Ce(III)-complex C2. Fig. S5. The 13C-NMR spectrum of Schiff base L2. Fig. S6. The 13C-NMR spectrum of Ce(III)-complex C2. Fig. S7. The mass spectrum of Schiff base L2. Scheme S1. The proposed fragmentation Scheme of Schiff base L2. Fig. S8. The mass spectrum of Ce(III)-complex C2. Scheme S2. The proposed fragmentation Scheme of the Ce(III)-complex C2. Fig. S9. DTA and TGA curves of Ce(III)-Schiff base complex (C2). Fig. S10. EDX images: [a–b] of Schiff base L2 and Ce(III)-complex C2. Table S1. Decomposition steps with the temperature range and weight loss for Ce(III)-Schiff base complex (C2). Table S2. EDX analysis of Schiff base L2. Table S3. EDX analysis of the Ce(III)-complex C2