Patent information: preparation method of lanthanum oxide-loaded zeolite for defluoridation.21115897.219999996

V fluoride is one of the essential trace elements for human body, and a proper amount of fluoride is essential to maintain the development of bones and teeth. However, drinking high fluoride water for a long time will lead to dental fluorosis and skeletal fluorosis, and even lead to bone deformation, pain, joint stiffness, tendon calcification, difficulty in walking and even paralysis. At present, there are still tens of millions of people drinking high-fluorine water in China, which seriously threatens human health. In order to explore the economic and effective methods and techniques of fluoride removal, this paper studies the fluoride removal performance of calcium-based bentonite, finds for the first time that the adsorption of bentonite to fluoride-containing solution can be divided into two parts, analyzes the adsorption law of bentonite to fluoride, and modifies it to prepare a series of bentonite fluoride removal agents. Through batch and column adsorption experiments, the defluoridation performance of bentonite series defluoridation agents and the feasibility of practical application were systematically studied. The main conclusions are as follows: (1) The adsorption isotherm equations of bentonite and its modified defluoridation agent products all conform to Fleundlich adsorption isotherm model. (2) In low concentration fluoride solution, the adsorption of fluoride ion by adding a certain amount of hydrochloric acid solution to calcium-based bentonite is mainly due to ion exchange. In high concentration fluoride solution, the adsorption of fluoride ion is mainly due to the exchange of Ca~(2+) in bentonite and Na~+ in solution. CaF_2 precipitate is generated or enters the electric double layer as counter ions to be removed. (3) The adsorption capacity of natural bentonite is low and the dosage is large. It can be modified by sulfuric acid and hydrochloric acid or zirconium oxychloride solution, and the fluoride removal ability of modified bentonite is significantly improved. However, there are some defects in the practical application of bentonite and its modified products, such as poor operating conditions, difficult solid-liquid separation of the treated mixed liquid, easy swelling during column adsorption and poor permeability, which limit its practical application. (4) Through experiments, polyvinyl alcohol was selected as the binder for granulation, and the granulation of bentonite products was realized. The prepared granular soil has good stability in water, among which zirconium loaded granular soil can be used for defluorination of wastewater, and granular acidic bentonite can be used for defluorination of drinking water and wastewater, and can be regenerated by 1% potassium aluminum sulfate solution, which has a good application prospect. (5) Both kinds of granular bentonite products have good adsorption capacity for fluoride ions, and the granular acidic bentonite after regeneration of preparation of bentonite defluoridator and the study of heirdefloridat-onProPerties shows a trend of better use. (6) The granular acid bentonite has a good operation effect when treating drinking water. Except for pH, all the indexes of the effluent meet the drinking water quality standard, and it also has a certain adsorption capacity for other harmful ions in the water. (7) The adsorption capacity of granular acidic bentonite is about 1/6-1/5 of that of activated alumina and bone charcoal, and about 3 times of that of zeolite. The effect of regenerated granular acidic bentonite is better than that of original granular acidic bentonite. The defluoridation performance of staggered bentonite is about four times that of granular acid bentonite. The cost of granular acid bentonite is slightly lower than that of activated alumina and boiling stone, but higher than that of bone charcoal. However, the cost of regenerant consumed by granular acid bentonite and zeolite is lower than that of bone charcoal and activated alumina, and the regeneration cost of bone charcoal is the highest. Granular acid bentonite can be used as an economical and effective defluorinating agent for drinking water treatment because of its low one-time investment and operation cost and good operation effect.