Study On The Modification And Defluorination Of Fuxin Natural Zeolite

Fluorine is one of the essential trace elements, the amount of fluorine is good for human growth, but the excessive fluorine intake will bring serious harm to human body. While the risk of dental fluorosis, fluorosis of bone, or lead to paralysis, even to death. At present, China's population of about 77 millions in the high fluoride in the water environment and long-term consumption of excess fluoride content of groundwater. Therefore, the research is of great significance to the effective method of fluoride. This subject are founded by the project of Liaoning Provincial Department of Education "Study on Preparation of Adsorbent Using Natural Zeolites in Fuxin (NO.L2012114)" and has completed the preparation and characterization of modified zeolites. In addition, the fluoride removing factors and mechanism of modified zeolites are also investigated.In this paper, natural zeolite was used as raw materials, modified respectively by using roasting, microwave radiation, hydrochloric acid, sulfuric acid, NaOH solution, MgSO4 solution, Al2(SO)3 solution, Ti(SO4)2 solution, EDTA, and DTAB as a single modifier and then fluoride removing experiment was carried out. The results show that:The fluoride removing effect of zeolite is preferably which modified by Ti(SO4)2 solution, under the test condition of zeolite particle size of 40 to 60 mesh, the temperature is 20?, pH velue is 7, concentration is 10 mg/L, fluoride removal capacity of the modified zeolite reached 0.928 mg/g, it is 6.7 times of the natural zeolite.Shock soaked in 1.0 mol/L NaOH solution under 40 ? for 24 h. Then soaked in 0.4 mol/L Ti(SO4)2 solution under 40 "C for 12 h with a solid-liquid ratio of 1:10 after washed and dried, composite modified zeolite was obtained.Static and dynamic experiment was carried out respectively by composite modified zeolite for removing fluoride, and the best condition of the static test is:reaction temperature is 20 ?, the reaction time of 300 min and pH value is 6-7. Using 6 g composite modified zeolite samples with granularity of 40-60 can make the fluoride ions concentration of the water of 80 mg/L down to 0.98 mg/L, meeting the needs of the level of below 1.0 mg/L by the industrial wastewater discharge standard, and the fluoride removal rate is of 98.8%. Adsorption process conforms to the secondary dynamics equation and the Freundlich adsorption model, is a spontaneous and heat release reaction. Optimal dynamic test conditions are:adsorption storey 20 cm, the flow rate of 5 mL/min, the qualified water yield reaches a maximum of 850 mL. The dynamic test results show that the adsorption process conforms to the Bed Depth Service Time adsorption model and dynamics equation of Thomas.In this paper, the morphology, composition and crystal structure of samples were characterized respectively by SEM, EDS and XRD detection methods. It was concluded that fluoride removing mechanism of composite modified zeolite was mainly through adsorption of [Ti(H2O)m(OH)2m-3n]n+ loaded on the surface.