The development of sorbents that combine high capacity with ease of extraction is critical for efficient water purification. This work presents a new type of composite particles that utilize the synergistic interaction of magnetite Fe3O4, calcium carbonate CaCO3 (aragonite), and polyacrylic acid. Structural analysis showed that optimal sorption properties are achieved at magnetite contents up to 20 wt %, while higher content promotes secondary phase formation and aggregation. Sorption tests confirmed the strong synergism of Fe3O4 and CaCO3: particles with 20 wt % Fe3O4 achieved a maximum sorption capacity for Methylene Blue of 645 mg g–1 that significantly exceeds the values for pure Fe3O4 and CaCO3. The obtained results confirm that the presented particles are promising, tunable magnetically extractable platforms for dye removal. It illustrates the general design principle in which the combination of complementary chemical functionalities provides sorption properties superior to the sum of the properties of the individual components.
Salnikov et al. (Mon,) studied this question.