Islam Mazahirul

When applied to wastewater treatment, natural gibbsite has a low fluorine capacity and is therefore rarely used. In this work, the gibbsite was calcined at different temperatures to improve the fluoride adsorption capacity. The adsorption responsible parameters, such as calcination temperature and time, initial fluoride concentration, dosage, reaction time and temperature were optimized. The results showed that the adsorption capacity of fluorine ion varies significantly by the gibbsite calcined at different temperatures. The best fluorine removal effect is the gibbsite calcined at 573 K for 0.75 h and its adsorption fluoride capacity of 8.3470 mg/g, which is 7.4 times that of natural gibbsite under the same conditions. Calcination temperature on its structural properties by means of scanning electron microscopy (SEM), thermogravimetric and differential thermal analysis (TGA/DSC), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) for the gibbsite were investigated. The results of characterization analysis showed that the phase composition of gibbsite calcined at different temperatures is different and the significantly different effect of fluorine removal may be attributed to the increase of specific surface area after calcination. The pseudo-second-order kinetic model and Langmuir adsorption isotherm model can better describe the fluorine removal process of gibbsite calcined at high temperature.