Study On Preparation Of Modified Imino Phosphonate Acid Resin And Its Performance Of Remove Of Fluorine

Fluorine is an essential trace element. Fluorine is one of the main components of thecomposition of human teeth and bones. Lack or excessive intakes of fluorine are detrimentalto human health. When the body long-term intake of excessive fluorine, conditions that couldcause abnormal metabolism of calcium and phosphorus, while inhibiting the activity ofenzymes, resulting in the endocrine system disorders, and ultimately lead to dental fluorosis,fluoride bone disease and other diseases, serious impact on health. As people continue toattach importance to human health and public health, endemic fluorosis is more and moreattracting people’s attention. Drinking water is the largest source of human ingested fluoride.When the fluorine content is more than1.0mg/L in the water, it is known as fluoridated water,also known as high fluoride water. Our country is relatively lack of water resources country;Fluorine pollution can cause some damage to water resources. Therefore it is particularlyimportant for the study of fluorinated water treatment methods and materials.In the water fluoride exists as Free State anion. Due to Pathologies concentration limit offluoridated water is very low (<1.0mg/L), and F-ion solution has a unique chemical properties,it is difficult to react with other substances, there are difficulties to depth removal tracefluorine from fluorinated water. Therefore, fluorinated water processing method andtechnology have been an important research topic. In recent years there have been manyresearches on treatment containing fluorine water at home and abroad, however manymethods of defluoridation exists some defects, such as high cost, large reagent consumption,low processing capacity, easy to cause secondary pollution, processing materials cannotregenerate. Therefore, it has a very important significance to look for a new type ofdefluoridation material and fluorine removal process which is simple operation, low cost,stable performance, high efficiency, and can be used in the actual production for the currentresearch of fluoride in drinking water problem.Currently, there are some theory difficulties on the study of fluorinated water treatmentmethods and processes, so that research methods to reduce fluoride from fluoridated waterhave not been practical application. This study proposed a new method for treatmentfluoridated water based on coordination chemical properties of fluoride ion, namely fluorideions and metal ions can form complexes of high stability in aqueous solution. In this paper,imino phosphonate acid resin as skeleton material, aluminum and zirconium are chelated onresin imino phosphonate acid groups. They forming coordination sites center, havingunsaturated coordination number complexes morphology. Ligand exchange adsorption can occur between ligand water on coordination sites center and trace fluoride by ligand exchange.So as to achieve the purpose of removing fluorine ion, and achieve fluoride material separatedfrom the solution.The main contents of this paper and the results are as follows.1. In this paper, iminophosphonate acid resin groups as skeleton material, aluminum and zirconium are as thecentral ions. We get two new types of modified imino phosphonate acid resin ligand exchangefluoride materials by dipping chelating process. This experiment identify the pH value,temperature, reaction time, solid-liquid ratio and other conditions of metal ion chelatingreaction in modification process. When the pH value is2, the temperature is50℃, thereaction time is3h, solid-liquid ratio is1:50, the immobilization rate of Al3+on iminophosphonate acid chelate resin is51.09%; When the pH value is1.1, the temperature is50℃,the reaction time is2h, solid-liquid ratio is1:50, the immobilization rate of ZrO2+on iminophosphonate acid chelate resin is36.87%. Infrared spectroscopy comparative analysisconfirms Al3+and ZrO2+are immobilized on the resin skeleton chelating group as the centralions, ligand exchange center was constructed, we get two types of modified resin ligandexchange fluoride materials.2. We use two kinds of modified resin material as defluorination materials, according toR.G. Pearson soft hard acid base theory, fluoride ion can form stable coordination compoundswith Al3+and ZrO2+on chelating resin. Two modified defluorination materials optimalconditions of defluorination reaction process are identified by defluorination experiment.Defluorination performance experiments show that two kinds of modified resin defluorinationperformance is fine. The cumulative removal rates of fluoride ion are up to93.18%and97.81%. In particular, the modified zirconium ligand exchange resins, in the processing of5mg/L~40mg/L concentration range fluorine-containing solution, after once defluorination,defluorination rate is up to97.81%, fluoride concentration in solution can meet the nationaldrinking water standards. Through the research in the eluting effects of variety of eluent usedfor two kinds of defluoridation materials, and the eluting effects of the same kind of eluentunder the condition of different concentration and pH value, ultimately we select oxalic acidas the eluent. Thereby the process conditions of the imino acid fluoride resin are improved.3. Through the research in the adsorption thermodynamics of defluoridation process, thefluorine adsorption process of two kinds of defluoridation materials conforms to theFreundlich, Langmuir isotherm adsorption. According to the Langmuir adsorption isotherm,the saturated adsorption capacities of fluorine ion for aluminium and zirconium ligandexchange resins are26.667mg g-1and71.429mg g-1. And we calculate the Arrhenius activation energy Ea of the two ligand exchange resins in adsorption thermodynamics process,the values are48.984KJ mol-1and144.0707KJ mol-1respectively. This indicates that thefluorine adsorption process of the two ligand exchange resins can occur, and can be conductedat room temperature.In summary, advantage of these two kinds of ligand exchange fluoride materials are lowcost, simple preparation process, the obvious effects of fluoride removing, so they have verygood application prospect.