|
The right amount of fluoride on human cellular enzymes beneficial to the reproductive system and can strong teeth and bones. But excessive fluoride is harmful to human health, causing fluorosis, fluoride water which is the main cause of endemic fluorosis. In China, the situation is quite serious fluorine pollution, fluoride water distribution throughout 29 provinces, autonomous regions and municipalities. Fluorosis can cause dental fluorosis and skeletal fluorosis, may result in severe tissue damage and skeletal deformities may also lose the ability to work. So fluoride water treatment to protect human health is very important. Currently, the fluoride treatment methods include coagulation and sedimentation, adsorption, electrochemical, membrane separation method, which is relatively common fluoride adsorption. Adsorption method is the key to high adsorption capacity of fluoride removal agent, so environmentally friendly, high adsorption capacity, Fluor is a focus of the study investigators. In this paper, shell sand as raw materials, citric acid or sucrose solution immersion, roasting, and then phosphoric acid, ammonia-modified materials or SPAS CPAS prepared materials, and to study the impact of factors during the preparation of the material were characterized. Prepared under optimum conditions with CPAS materials and SPAS material, study materials, fluoride treatment conditions, such as solution pH, adsorption time, dose, concentration of the initial solution and coexistence fluoride ion impact, while the filter column study materials testing and SPAS recycled materials testing, and finally discuss the reaction mechanism, get some main conclusions: (1) The citric acid or sucrose, phosphoric acid, ammonia-modified shell sand prepared two new efficient fluoride materials. (2) Preparation of CPAS materials, the best conditions: the mass fraction of 5% citric acid solution to liquid ratio of 1:5 soaked 24 h, washed eight times, drying, 600 ℃ calcination] h, with 0.6mol · L- a phosphoric acid solution to liquid ratio of 1:30 soak 3 h, and then adjusted to pH 8 ammonia at room temperature aging 3h. (3) Preparation of optimal conditions for SPAS material: 5% sucrose solution mass fraction solid-liquid ratio of 1:10 soaked 24 h, filtration, drying, 500 ℃ calcined 2h, with 0.6mol · L-1 phosphoric acid solution soaked with liquid ratio of 1:30 0.25h, and then aqueous ammonia to pH 8, aged at room temperature 3h. (4) Materials for CPAS and SPAS factors found fluoride solution fluoride concentration, pH and fluoride doses have a certain influence on the material, while coexisting ions have little effect. SPAS CPAS material or material dosage 1.33 gL-1, pH of the solution in the 3-10 range, handling 12 h, the removal of fluoride were above 95%. (5) on the material and the SPAS materials CPAS dynamic filter column test study materials and SPAS material obtained CPAS on fluoride removal capacity was 7.53 mg.g1 and 7.67mg · g-1. SPAS material after repeated regeneration decreased fluoride removal. (6) Material fluoride mechanism is the CPAS and SPAS material OH ~ - and F ~ - ions occurs (lattice) as well as the role of exchange or replacement CPAS and SPAS materials F ~ - adsorption.
|