Preparation And Characterization Of Mg-Fe-La Composites

Here, Chaerhan salt lake brine was used as raw material to prepare Mg-Fe-La composite material for fluoride removal by a facile co-precipitation method. The structures and interface properties of the as-prepared adsorbent were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD), Fourier Transform infrared(FT-IR), X-ray photoelectron spectroscopy(XPS) and Brunauer-Emmett-Teller(BET). The adsorption thermodynamics and kinetics were studied, and the safety of the composite material was also researched in this article.The solid phase extraction experiments were carried out and the possible adsorption mechanisms were put forward. The experimental conclusions were as follows.(1) Chaerhan salt lake brine was used as raw material to prepare Mg-Fe-La composite material by a facile co-precipitation method in this study. The results proved that the Ca2+ and Cl-in the salt lake brine had no effect on the fluoride removal performance. When the Mg/Fe/La mole ratio was 25:1:4; synthesis temperature was room temperature(25 o C); calcination temperature was 400 o C; the largest adsorption capacity for fluoride could reach 112.17 mg/g.(2) EDS analysis results indicated that the actual compositions of Mg-Fe-La composite material were consistent with the theory compositions. The BET surface area, average pore diameter and particle size of the Mg-Fe-La composite material were 178.55 m2/g, 31.16 nm and 0.727 μm, respectively.(3) Adsorption thermodynamics research showed that the adsorption process wa fitted well with the Langmuir isotherm, indicating monolayer adsorption. The relate thermodynamic parameters showed that the adsorption process was a spontaneou exothermic process and low temperature was beneficial to the adsorption behavior.(4) Adsorption kinetics study showed that the adsorption process reached equilibrium state after 4 h. The adsorption process was mainly irreversible chemical adsorption. In addition, the adsorption process was fitted well with the pseudo-second-order kinetic model.(5) The solid phase extraction experiments indicated that Mg-Fe-La composite material could be used for dynamic adsorption and had no effect on the p H of water.The ICP analysis results showed that there was no metal ion dissolution during the adsorption process, which would not cause the secondary pollution.(6) Based on the results of FT-IR, XPS, Zeta potential, the adsorption kinetics and thermodynamics models, the adsorption mechanisms of the Mg-Fe-La composite material were considered as complexation and ion exchange.