Study On Preparation Of Fluorine Removing Gelatum Based On Ligand Exchange And Its Performance Of Removing Fluoride

Fluorine is one of the essential trace elements in life activities with a wide range ofphysiological effects. But it will cause kinds of harm if intakes too much. The excess exists offluorine in human body will destroy the normal metabolism of calcium and phosphorus andinhibit the role of enzyme which affect the endocrine function and causes fluorosis at lastwith signs of skeletal deformities, lumbar stiffness and so on. The main way of human intakeof fluorine is drinking high fluorine content water, so the process of fluoridated watertreatment is particularly important.There are certain difficulties in removing the trace amount of fluorine from water, so theprocess of fluoridated water treatment is an important issue in environmental protection andhealth research from home and abord. Currently, there are some limitations in the commonmethods and processes of defluoridation. Therefore, it has great significance in searching fornew defluoridation materials with a suitable price and simple operation while the rate ofdefluoridation is effencial.This study proposes a new treatment in removing fluorine from drinking water. It startsfrom searching for an appropriate skeleton not dissolve in water which can occur graftingreaction with amine. We select Polyacrylamide Gel （PAG） as a reinforcing material and graftchelating groups from the Mannich reaction. Then fix Fe³⁺and Al³⁺to the skeleton andremove fluorine from water using the role of coordination to achieve the solid-liquidseparation.In this paper, we use Polyacrylamide Gel as skeleton and formate three different groupsof amine chelate from grafting DETA and TETA and IDA based on its pore structure of PAG.Through the research in affert of ratio of materials and reaction pH and temperature and time,the results showed that the graft rate of IDA is up to96.58%while its90.51%of TETA and79.60%of DETA. In the experiments of metal-chelate grafted gel, we choose Fe³⁺and Al³⁺aschelating metal and investigate the affect of factors in chelation reaction such as reaction pH,reaction temperature, time and the initial concentration of metal. The results showed that theprocess conditions of grafting Fe³⁺is more moderate and has more higher metal loading rate than that of Al³⁺. By using the six fluoride removing gelatum based on Ligand Exchange influoride removal experiment, the reaults show that Al³⁺-chelate grafted gel is significantlybetter than that of Fe³⁺while dealing with low-concentration fluoridated water. Among thesematerials, the performance of fluoride removal is similar between Al³⁺-chelate grafted gelwith IDA and that of DETA with the rate of94.3%and95.4%and the rest concentration of F-comply with the national standards for drinking water. It has the same affect while dealingwith high-concentration fluoridated water and the Al³⁺-chelate grafted gel with IDA has themost performance.Through research on the mechanism of defluoridation, the process of defluoridation canbe regarded as the adsorption process. It matchs the Langmuir adsorption by fitting theadsorption concentration. The adsorption capacity of the five fluorine removing gelatumbased on ligand exchange is from2.96mg·g^-1to3.54mg·g^-1.Through the calculation of theapparent activation energy of the defluoridation process, the average is54.7407KJ·mol^-1. Sothe process is of ligand exchange and we can consider that it has produced a coordinationbond during this process.Through the new idea of defluoridation, a novel and low-cost method to remove F-fromdrinking water is obtained.