Novel Hybrid Polymer Materials with Magnetic Properties for Effective Purification of Aqueous Environments

A series of pectin/polyethylenimine (Pectin-PEI) composites was developed in combination with other components such as Fe 3 O 4, activated carbon, complexing metal ions, and HCl to optimize the removal of methyl orange (MO) from aqueous solutions. The PEI content in the samples ranged from 35 to 53 wt %. The morphology of the obtained samples was analyzed by using SEM images, and their composition was determined through elemental analysis, EDX spectra, and acid–base titration. The adsorption capacity for methyl orange was studied, which for the initial (nonprotonated) samples was 814–1460 mg/g. A significant increase in affinity for MO was observed for protonated samples (1516–2470 mg/g), as well as for composites loaded with metal ions like Cu 2+, Zn 2+, and Fe 3+ (1246–3015 mg/g). According to the diffuse reflectance spectra of samples with adsorbed MO, the formation of H- and J-aggregates of MO was confirmed. The most effective sorbent was the sample containing PEI with a molecular weight of 0.61 × 10 6 Da at a pectin-to-PEI weight ratio of 1:2. Based on this, magnetic composites with Fe 3 O 4 and activated carbon were produced. The materials were prepared both by solid-phase dispersion of mixtures of Pectin-PEI, activated carbon (AC), and Fe 3 O 4 and by direct formation of a cross-linked Pectin-PEI product in a mixture of AC and Fe 3 O 4 . The highest efficiency was demonstrated by samples with Pectin-PEI:AC:Fe 3 O 4 ratios of 36:54:10 and 45:45:10. To examine the adsorption characteristics, the composite samples were prepared as hydrochloride and metal complexes with Cu 2+, Zn 2+, Cd 2+, Hg 2+, Pb 2+, and Fe 2+ . The kinetics of methyl orange adsorption from aqueous solutions were analyzed using various models, including pseudo-first-order, pseudo-second-order, intraparticle (Weber-Morris), and film-diffusion models.