Newly modified silica-based magnetically driven nanoadsorbent: A sustainable and versatile platform for efficient and selective recovery of cadmium from water and fly-ash ameliorated soil

• Novel and stable magnetically driven silica based nanoadsorbent.
• Highly efficient for selective recovery of cadmium from environmental samples.
• Equilibrium, kinetic and thermodynamic parameters were investigated.
• Facile separation using external magnet.
• High reusability with good adsorption performance for eight consecutive cycles.

The interface of magnetically driven nanotechnology with solid phase extraction methodology has been realized to form a novel nanoadsorbent via covalent linkage of amine functionalized silica-coated magnetic nanoparticles with a newly synthesized Schiff’s base. The final nanoadsorbent and parental nanosupport, with each step of successive modifications, were characterized by SEM, TEM, EDS, XRD, VSM and FT-IR. The nanoadsorbent was examined as a versatile, potent, promising and sustainable platform for highly selective determination, separation and recovery of cadmium from the environmental matrix. Further, the sorption equilibrium followed Langmuir isotherm model, and the maximum sorption capacity was found to be 200 mg g−1 at 318 K. The adsorption rate agreed well with pseudo second-order kinetics and the evaluated thermodynamic parameters suggested that the sorption process was endothermic, spontaneous and energetically favourable in nature. Desorption of cadmium ions was readily achieved with ultrasonic assisted mild acid treatment. Moreover, the stability and preconcentration efficiency of the recovered magnetic nanoadsorbent was retained over several separation cycles. Under optimal conditions, detection limit, preconcentration factor and relative standard deviation for six replicate extractions are 0.11 ng mL−1, 250 and 2.1% respectively. In addition, the proposed protocol was successfully applied with an excellent reliability and reproducibility for the recovery of Cd2+ ions from water and fly-ash ameliorated soil samples.

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