Biopolymer-Based Magnetic Nanocomposites and Their Flocculating Properties

Magnetic flocculants based on Fe3O4 magnetite nanoparticles and natural polysaccharides (chitosan and apple and citrus pectins) have been synthesized. Magnetite has been functionalized at an optimal biopolymer : magnetite ratio of 5 : 1. Individual particles of magnetite, polysaccharides, and magnetic flocculants based thereon have been characterized by dynamic light scattering, IR spectroscopy, and СHN-analysis. NMR-relaxometry has been employed to show that the distribution of these systems in biological media can be studied using magnetic resonance tomography. The concentration of magnetic flocculants based on magnetite and natural polymers and the pH value of the medium have been varied to study their effects on the flocculating parameters of the system. Among the studied magnetic flocculants, chitosan-based magnetic flocculant (MFC) has the greatest flocculating effect at a concentration of 2 × 10–2 g/L. The efficiency of flocculation in a suspension of blue clay with the participation of MFC has been shown to increase in a highly alkaline pH region. It has been found that the sedimentation of clay with the participation of magnetic flocculants based on citrus and apple pectins occurs via a bridging flocculation mechanism, while the neutralization mechanism of flocculation is mainly realized with the participation of the MFC. It has been shown that the highly efficient multifunctional flocculant is selective for the separation of multicomponent disperse systems.