Surface modification with EDTA molecule: A feasible method to enhance the adsorption property of ZnO

• First study on surface adsorption of EDTA-functionalized ZnO nanoparticles.
• EDTA was chemically immobilized on ZnO.
• The immobilized EDTA species enhanced the adsorption capacity of ZnO.
• The immobilized EDTA changed the adsorption mechanism of ZnO.
• The functionalized ZnO can be a promising adsorbent for removal of metal ions.

Surface-functionalized zinc oxide (ZnO) nanoparticles were synthesized with ethylene diamine tetraacetic acid (EDTA) as a modification agent, which were used as adsorbents in the adsorption of Cu2+ at certain conditions. The transmission electron microscopy (TEM) results show that the average size of ZnO particles is about 45 nm, and it exhibits hexagonal wurtzite structure. Fourier transform infrared (FTIR) spectra reveal that the EDTA species are chemically bonded on the surface of ZnO. Compared with bare ZnO particles, the functionalized ZnO nanoparticles have a better activity in the Cu2+ adsorption. The maximum adsorption capacity of functionalized ZnO nanoparticles is 20.97 mg/g, while it is 17.93 mg/g for the bare ZnO. The adsorption isotherm of bare ZnO particles is in accordance with the Freundlich model, and the chemical adsorption is in a dominant position in the adsorption process of Cu2+ on functionalized ZnO particles.

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