Smart Magnetic Ferrite/Organoclay Composites for Sustainable Water Remediation

In this study, magnetic spinel ferrites (i.e., CoFe2O4 and NiFe2O4) are embedded in an organically modified montmorillonite clay using selected alkoxysilanes, forming magnetic ferrite/organoclay composite systems. These prepared composite materials, along with pristine ferrites and montmorillonite, are characterized employing different physicochemical, morphological, structural, and magnetic characterization techniques. Additionally, magnetic ferrite/organoclay composites are tested as sorbing substrates in environmental remediation processes for the removal of target dye species from aqueous matrix. Kinetics tests validate that the kinetic mechanism concerning both composite systems seems more related to the involvement of chemisorption phenomena associated with surface interactions. Lastly, experimental adsorption isotherm tests, explained by means of the most common models, demonstrate that the CoFe2O4/modified-montmorillonite composite seems better described by the Langmuir model (monolayer coverage) with a theoretical maximum adsorption capacity (qm) of 8.46 mg·g-1, whereas the NiFe2O4 analogous seems better described by the Temkin model with a qm value of 13.44 mg·g-1 (more governed by adsorbent–adsorbate interactions and adsorption energy). The demonstrated effectiveness of these magnetic sorbent systems opens the way to their application as magnetically recoverable materials, potentially recyclable, and reusable for sustainable water remediation applications.