Adsorptive Removal of Copper (II) Ions from Aqueous Solution Using a Magnetite Nano-Adsorbent from Mill Scale Waste: Synthesis, Characterization, Adsorption and Kinetic Modelling Studies

In this study, magnetite nano-adsorbent (MNA) was extracted from mill scale waste products, synthesized and applied to eliminate Cu2+ from an aqueous solution. Mill scale waste product was ground using conventional milling and impacted using high-energy ball milling (HEBM) for varying 3, 5, and 7 milling hours. In this regard, the prepared MNA was investigated using X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), field emission scanning electron microscopy-energy-dispersive X-ray spectroscopy (FESEM-EDS), UV-Vis spectroscopy, Fourier-transform infrared (FTIR), Brunauer-Emmett-Teller (BET) and zeta potential. The resultant MNA-7 h milling time displayed a crystalline structure with irregular shapes of 11.23 nm, specific surface area of 5.98 m(2)g(-1), saturation magnetization, Ms of 8.35 emug(-1), and isoelectric point charge at pH 5.4. The optimum adsorption capacity, q(e) of 4.42 mg.g(-1) for the removal of Cu2+ ions was attained at 120 min of contact time. The experimental data were best fitted to the Temkin isotherm model. A comparison between experimental kinetic studies and the theoretical aspects showed that the pseudo-second-order matched the experimental trends with a correlation coefficient of (R-2 > 0.99). Besides, regeneration efficiency of 70.87% was achieved after three cycles of reusability studies. The MNA offers a practical, efficient, low-cost approach to reutilize mill scale waste products and provide ultra-fast separation to remove Cu2+ from water.

Automated summary

In this study, magnetite nano-adsorbent (MNA) was successfully synthesized from mill scale waste products and applied for the removal of Cu2+ from aqueous solutions. The optimal MNA with specific characteristics was obtained after 7 hours of milling time. The experimental results demonstrated high adsorption capacity and regeneration efficiency of MNA, making it a promising candidate for water treatment applications.