Fluoride Removal From Drinking Water By La-Ce-Cu-Zn Alloy Filter Media

Flouride is necessary for our health. But drinking water containing high fluoridewill be harmful to our health after long-term consumption. In the paper, theCu-Zn-La-C alloy filter media was used for the removal of fluoride from drinkingwater. The batch experiments were performed for investigating the influence factorson the removal of fluoride, such as the size of filter material particle, filter materialdose, contact time, temperature, initial concentration of fluoride, value of pH.Moreover, height of filter material, flow rate, temperature, initial concentration offluoride, value of pH, and the effect of co-existing ions was also evaluated in thecolumn experiments. The mechanisms of fluoride removal were explored by kineticsand thermodynamics studies, and Scanning Electron Microscope/Energy dispersiveX-ray spectroscopy. The research indicated that the Cu-Zn-La-C alloy filter mediahad shown good performance of fluoride removal from drinking water, and haspotential application prospects.The research results and conclusions as follows:1. The method of fluoride ion selective electrode was used to determine theconcentration of fluoride ions in solutions. When the mixing time is kept at5min andthe volume of adding TISAB is10mL, the voltage signal is stable. The working curveis linear in the range of0.05–8mg/L, the corresponding equation of linear regressionis E=-56.35logCF-+115.66（R=0.9990）.2. The optimal conditions of batch experiments were obtained as follows:contact time,120min; experiment temperature, room temperature; pH6.5; the dose ofthe filter material,6g; initial concentration of fluoride,5mg/L. Under the aboveconditions, the concentration of fluoride ions was reduced to be0.746mg/L, and thecorresponding efficiency of fluoride removal85.0%.3. The optimal column experiment conditions were obtained as follows:experiment temperature, room temperature; the flow rate,5mL/min; pH=8.5; theheight of filter material,7cm. Under the above conditions, the efficiency of fluorideremoval is86.2%, and the corresponding fluoride concentration of fluoride removal 0.690mg/L. Moreover, the influences of co-existing ions including Mg²⁺, Ca²⁺, Fe3+,Cl-, SO₄^2-were examined. Mg²⁺, Ca²⁺and Fe³⁺can promote the fluoride removal; Cl-and SO4^2-have less effect on the fluoride removal; CO3^2-and HCO₃^-have negativeinfluence on fluoride removal.4. The Langmuir isotherm model can match the experiment better than theFreundlich isotherm model. Thermodynamic parameter was ΔH0＞0，ΔG0＜0. Itindicated that the fluoride removal is endothermic and spontaneous process.Lagergren second order kinetic model can match the experiment better thanLagergren first order kinetic model. Adsorption rate increase with the increase oftemperature. Based on the results of the kinetics and thermodynamics studies andSEM analysis, the possible mechanism for fluoride removal from drinking water isthrough the physical adsorption after the chemical reaction.5. The Cu-Zn-La-Ce alloy filter media was used for removing fluoride ions fromthe synthesized water samples. When a column with a diameter of60mm was used toremove fluoride at a flow rate of12L/min and a filter height of4cm, the fluorideconcentration in the effluent solution was found to be0.75mg/L, which did notexceed the national safety stands for drinking water.