[Mg/Al layered double hydroxides prepared by microwave-assisted co-precipitation method for the removal of bromate]

In this paper, Mg/Al layered double hydroxides (Mg/Al LDHs) were prepared by the microwave-assisted co-precipitation method and the conventional co-precipitation method. The samples were labeled as Mg/Al LDHs-MW and Mg/Al LDHs-H, respectively. Mg/Al LDHs were characterized by X-ray diffractometer (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). The results showed that the application of microwave in the preparation process promoted the formation of smaller pore diameter and higher crystallinity particles. The pore size and particle size of Mg/Al LDHs-MW were 41.13 nm and 427.08 nm, respectively. Batch experiments were investigated to evaluate the effect of dosage, initial pH and regeneration frequencies for bromate removal. The conclusion showed that the process of bromate removal on Mg/Al LDHs could be described by the pseudo-second kinetic model. The Langmuir isotherm well described the experimental data, and the Mg/Al LDHs-MW has a stronger adsorption capacity while the maximum adsorption capacity (q(0)) of Mg/Al LDHs-MW for bromate was 321.26 microg x g(-1) which was larger than the q(0) (288.74 microg x g(-1)) of Mg/Al LDHs-H. For the continuous fixed-bed column, model simulations using the Thomas model showed that the experimental data obtained at three different columns packed with Mg/Al LDHs-MW were able to predict breakthrough curves. Simulating the maximum adsorption capacity of adsorption column for bromate removal was 288.81 microg x g(-1). When the bed depth was 10 cm, inlet concentration was 800 microg x L(-1) and flow rate was 4.0 mL x min, the correlation coefficient of model was 0.92, indicating that the experimental data was described well by the Thomas model.