Preparation Study Of Ce-loaded Fly Ash Adsorbent And Removal Fluorides From Groundwater

High-fluorine in groundwater is the main reason for the endemic fluorosis. In our country, the high-fluorine-groundwater are mainly distributed in the provinces of Inner Mongolia, Shanxi, Gansu and other regions. Especially in Inner Mongolia, it abounds in natural resources. In the process of exploitation and use, it resulted in varying degrees of fluorine pollution. The limit of fluoride in groundwater is less 1.0mg/L in China. For the fluoride contamination in groundwater, the adsorption is aneffective method. In my paper, we developed a new type of adsorbent——Ce-loadedfly ash adsorbent, for the fluoride removal on groundwater. It includes four parts:In my study, a novel adsorbent, Ce-loaded fly ash adsorbent was prepared. The conditions of preparation of the adsorbent were investigated. The conditions of preparation was obtained: modified acid concentration 6mol/L, cerium ions concentration 0.2g/L, calcinations temperature 400℃and contact time 16h.In the second part of this paper, the adsorption characteristics of this adsorbent for fluoride were analyzed under various conditions, such as pH, adsorbent dosage, initial concentration and agitation time. In addition, the salinity and rigidity of solution did not interfere with fluoride adsorption by the adsorbent. Both nitrate and phosphate showed some adverse effects, existed great competitive adsorption with fluoride on the adsorbent.In the third part, the thermodynamics and kinetics in the process of adsorption of fluoride on adsorbent were analysed. The adsorption capacity increased with rising temperature. In the isotherm studies, Langmuir and Freundlich isotherm models were applied and it was determined that the experiment data conformed to Langmuir isotherm model. As a result of kinetics, it was observed that the adsorption data conforms to Lagergren's pseudo-second-order rate mode. Thermodynamic parameter such as change in free energy(G°), enthalpy(H°), entropy(S°) were also determined. The investigation on desorption experiment indicated that this adsorbent is easily regenerated by use of NaOH solution. The desorption amount of fluoride is up to 95% in 30 min. In addition, column studies and leaching heavy metal were made. The Thomas and the Yoon-Nelson models were applied to experimental data to predict the breakthrough curves and to determine the characteristics parameters of the column useful for process design. The capacity value for column study was obtained by calculated as 40.47mg/g, 40.33mg/g. As a result of the metal leach-out, it was observed that the adsorbent fitted for removal fluoride on groundwater.In the last part, the adsorption mechanism was proposed on basis of analysis SEM, XPS, XRD, surface area and surface charge of adsorbent. It can be concluded that the fluoride of adsorption process maybe conform to the model of surface complexation,...