Zn2+–Silica Modified Cobalt Ferrite Magnetic Nanostructured Composite for Efficient Adsorption of Cationic Pollutants from Water

摘要

A Zn2+–silica modified CoFe₂O₄ (CZFS) nanostructured composite, useful for adsorbing cationic pollutants from water, was prepared by a wet-chemical method. The composite comprises cubic spinel crystallites (average 18 nm size) with amorphous silica clusters decorated on the crystallites-surface. Improved surface area (59.8 m2/g) of CZFS over those of Zn2+ modified CoFe₂O₄, CZF (32.6 m2/g), and CoFe₂O₄, CF (42.8 m2/g), together with its high negative ζ-potential of ?35.4 mV (from surface SiO–) provides CZFS with improved adsorption capacity for Methylene blue (MB) over that of CZF and CF. MB adsorption (initial adsorbate concentration C₀ = 5–25 mg/L) conforms to the Langmuir isotherm model, with maximum monolayer adsorption capacity Q_m = 25.6 mg/g. CZFS exhibits adsorption efficiency A_e ≥ 98% for removal of heavy metal ions Cr3+, Cu2+ and Pb2+ (C₀ = 5 mg/L). High A_e = 99.9% for Pb2+ dropped only to A_e = 98.8% for higher C₀ = 20 mg/L (Q_m = 19.8 mg/g). Saturation magnetization of 39 emu/g enables easy magnetic separation of CZFS from water. Good reusability of CZFS adsorbent was observed for up to three cycles. In summary, CZFS efficiently removes MB as well as heavy metal ions (especially Pb2+) from contaminated water.]]>