Preparation Of Ultrasonic Assisting Ferric Chloride Modified Cinder And Fluoride In Performance Research

This study, through the orthogonal experiments and single factor experiments,evaluated the effectiveness of cinder in removing fluoride from solution. Usingcinder as raw materials for sulfuric acid modification, sodium hydroxidemodification, high temperature modification and ultrasonic modification on thisbasis, found the ultrasonic modification was the best one. The fluorideadsorption on UC and cinder were well described by the Langmuir adsorptionmodel. Under the same experimental conditions, the fluoride adsorption capacityof UC was1.54times of cinder, reached0.9726mg/g.Ultrasonic assisting ferric chloride modified cinder (UFC) was prepared toimprove adsorption capacity for fluoride. Batch experiments were performed totest and optimize various operational parameters such as mixture of pH,concentration of ferric chloride solution, aging time and ultrasonic order. Resultsshowed that the best preparation conditions of UFC as follows: mixed cinderand FeCl3solution in1:5(W/V), adjusted pH to7, oscillated mixture with100%oscillation frequency of in the60min at30℃, and last dried at105℃.Infrared spectrometry (IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX),thermogravimetric analysis surface (TG) and surface area analysis (BET) wereused to characterize the adsorbents. Results revealed that with ultrasonicmodification, the changes of cinder’s structure and thermal stability could beignored and its specific surface area decreased while active site increased whichimproved the adsorption of cinder. Compared with cinder, the content of Fe inUFC increased, iron oxide covered on the surface of cinder leading to biggerspecific surface area and poor thermal stability. The figure of XRD and EDXtold that iron oxides played an important role in the process of adsorption.Adsorption experiments suggested that pH of solution had a negligibleimpact on the UFC removing fluoride. UFC which was more effective thancinder and UC showed the highest fluoride adsorption capacity of2.139mg/gand removal percentage of85.24%when the dose was20mg/L. Equilibriumadsorption isotherms and kinetics were investigated. The results were achievedwith the Langmuir isotherm model and the pseudo-second-order kinetic withliquid film diffusion as the rate determining step. In addition, thermodynamicparameters indicated that the adsorption process of fluoride on UFC was aspontaneous and endothermic process of entropy increase.