Magnetically responsive ferrite/organoclay composites for water remediation

Magnetic ferrite/organoclay composites were developed as magnetically recoverable adsorbents for water remediation. Spinel ferrites (i.e., CoFe2O4 and NiFe2O4) were incorporated into an organically modified montmorillonite clay using GPTMS and APTES alkoxysilanes as coupling agents. These composite materials, along with pristine ferrites and montmorillonite, were characterized in terms of morphology, structure, surface properties, and magnetic behavior. Magnetic ferrite/organoclay composites were tested as sorbing substrates for the removal of Methylene Blue dye species from aqueous matrix. Compared to pristine ferrites (3.58–2.93 mg g−1), the composites exhibited enhanced adsorption capacities of 4.73 mg g−1 (CoFe2O4-based composite, with removal efficiency of 50.6%) and 8.29 mg g−1 (NiFe2O4-based composite, with removal efficiency of 88.5%). Kinetic analysis indicated the predominance of pseudo-second-order mechanisms, suggesting the involvement of surface-mediated interactions. Magnetic composites exhibited enhanced adsorption performances compared to pristine ferrites, with maximum capacities of 8.46 mg g−1 (CoFe2O4-based composite) and 13.44 mg g−1 (NiFe2O4-based composite), and distinct adsorption behaviors described by Langmuir (monolayer coverage) and Temkin (more governed by adsorbent–adsorbate interactions and adsorption energy) models, respectively. The efficacy, structural integrity, and facile magnetic separation of these sorbent systems demonstrate significant potential as stable, recoverable materials for sustainable water remediation.