LAUSR

Abstract In order to explore the effect of SO42– in natural water on the defluorination behaviors of different types of aluminum salts, a coagulation experiment by simulating raw water in the laboratory was conducted. After jar tests, the aluminum forms in supernatant were analyzed by ESI-TOF-MS, and the precipitation was characterized by solid-state NMR and XPS. The results show that when AlCl3 is used as a coagulant, as the rise of SO42– content, the production of Al(OH)3 is almost unaffected. In addition, AlCl3 can be hydrolyzed to form a small amount of polyaluminum species, and they also have a defluorination function. When these polyaluminum species encounter SO42–, they react with it to generate Al-SO4 co-precipitation, which reduces the content of Al-F complex and hinders the defluorination. When Al13 is used as the coagulant, the low content of SO42– enhances the attack of F- on Al13, and reacts with a large number of Al-F complexes to produce Al-SO4 co-precipitation, releasing F–, and rapidly decreasing the defluorination rate. The high content of SO42– reacts weakly with Al-F complex. As its content rises, the defluorination rate slowly decreases.