Influence of particle size on fluoride removal by La2O3 . nH2O.

The best pH range for fluorine removal using La_2O_3·nH_2O,and the influence of particle size on its defluorination capacity and dynamics were studied in this paper.On this basis,the defluorination capacity of La_2O_3·nH_2O was compared with activated alumina.The experimental results showed that:the best pH range of fluorine removal using La_2O_3·nH_2O was 5.5-6.5;the adsorption of fluoride on La_2O_3·nH_2O accorded with the Langmuir single molecular layer adsorption principle;and,the maximum adsorption capacity and adsorption rate were significantly improved with the particle size decreasing.In these experiments,the maximum adsorption capacity of La_2O_3·nH_2O with size 0.038-0.050 mm was 3.32 times as much as that with size 0.500-0.710 mm,and when the balance fluoride concentration was 1 mg/L,the calculated adsorption capacity of the former size was 10.13 times as much as that of the latter size.Compared with activated alumina,when the balance fluoride concentration was 1 mg/L,the capacity of La_2O_3·nH_2O was 2.55-13.88 times as much as that of activated alumina with the same particle size.