Preparation Of Zeolite Modified By Pfs And Its Ability For Arsenic,fluoride Removal

Serious drinking water problem exists in many rural areas of our country due to the constraints of natural, social, and economic conditions. China has become one of the most serious countries with drinking water fluoride and arsenic poisoned, which is harmful to people in these contaminated areas. Lowering fluoride concentration and removing arsenic from drinking water is an effective measure to improve water quality and prevent sickness related to fluoride and arsenic. The main methods include coagulation and precipitation, adsorption, ion exchange, membrane separation. Each of them has advantages, and also disadvantages. Therefore, common water purification method should be improved, and new water purification materials should be developed to enhance the quality of drinking water. In this paper, natural zeolite modified by polyferric sulfate (PFS) for water purification were prepared by impregnation.Various factors which include active component solution, impregnation concentration, impregnation time, ratio of solid to liquid, and drying temperature are studied so as to determine the optimal experimental conditions. The best preparation conditions of modified natural zeolite are determined. The active component is PFS, which solid content is 44%, the impregnation time is 1.5h, the ratio of solid to liquid is 1:5 and the drying temperature is 105℃.SEM, EDS are used to analyze the natural zeolite modified by PFS. The results show that impurity on the surface is decomposed and the porous channels are opened. The specific surface area and porosity of the natural zeolite increased after modified by PFS. The iron is loaded on the natural zeolite by replacing ions in the crystal structure of natural zeolite, which is not changed after modifying. XRD shows that there are FexSiOy and Fe2O3 in the modified zeolite.The ability of removing fluoride and arsenic by natural zeolite modified by PFS is discussed. The study found that the static saturated capacity of fluoride removal is 25mg/g, the capacity of arsenic removal is 4mg/g. The influencing factors (flow rate, initial concentration, PH value, bed height and sample consumption) on the fluoride, arsenic removal are also investigated by dynamic defluorination experiments. While the residence time and the bed height were 68s and 47mm respectively, the initial fluoride concentration would be decreased from 5.8mg/L to 0.95mg/L by the natural zeolite modified by PFS, lower than the limit 1mg/L. And the best fluoride removal residence time and the minimum bed height of the modified zeolite could be reduced when the initial fluoride concentration was falling; While the flow rate, the residence time and the sample consumption were 2.2L/min, 3.2s and 100g respectively, the initial arsenic concentration could be declined from 0.1mg/L to less than 0.01mg/L, meeting the national drinking water standard. The sample consumption could be reduced when the flow rate decreased. The natural zeolite modified by PFS for arsenic removal could be adapted to different PH value of water.The natural zeolite modified by PFS has a certain life in the fluoride, arsenic removal with dynamic capacity of fluoride removal 183μg/g and arsenic removal 63μg/g.