Facile preparation of mesoporous silica/nano zero-valent iron composite for Pb(II) removal from aqueous solution

Nano zero-valent iron (NZVI) particles were prone to forming aggregates owing to their intrinsic magnetism and van der Waals force. In this work, a composite material containing mesoporous silica MCM-41 and NZVI was prepared to avoid the problem of NZVI aggregation. The structures and morphologies of the as-prepared composite were confirmed using X-ray diffraction, Fourier transform infrared spectrometry, transmission electron microscopy, N-2 adsorption-desorption, and X-ray photoelectron spectroscopy techniques. It was found that NZVI particles were well dispersed in the composite, although the size of NZVI particle was larger than that of bare NZVI. Moreover, the composite was used as adsorbent for removing Pb(II) from aqueous solution at room temperature. The effects of contact time, initial solution pH, and adsorbent dosage on the removal efficiency of Pb(II) were studied using batch adsorption experiments. The results indicated the composite exhibited enhanced adsorption properties, with the maximum adsorption capacity of 416.17mg/g for Pb(II) removal from aqueous solution. In addition, the adsorption isotherms and adsorption kinetics were also investigated systematically, it was found that the isothermal data were well fitted to Langmuir model, and the kinetic data were well suitable to pseudo-second-order kinetics model.