[Study on the defluoridation of drinking water with model-La cation exchange resin]

Model-La cation exchange resin was transformed from strong acid cation exchange resin, which was used for the defluoridation of drinking water. The 001 x 7 strong acid cation exchange resin was transformed into model-La cation exchange by soaking in the La(NO3)3 solution. The F- in the water was removed by model-La cation exchange resin under the optimum condition because it was combined into fluoride with the La3+ in the model-La cation exchange resin. The used resin was regenerated with the La(NO3)3 solution and was used to defluoridate many times. The optimum conditions of transform and defluoridation and regeneration were d(rasin) = 0.315-0.600 mm, V(rasin):V(regeneration) = 1:6, t(transform) = 48 h, T = 298.16 K(25 degrees C). The defluoridation capacity was 5.60 mg/g in column test, and 4.08 mg/g in batch test. The model-La cation exchange resin could be used for defluoridation for 8 times. The results suggest that the model-La cation exchange resin is a novel material of defluoridation. This method is easy to master and the pH value of the solution doesn't need to be regenerated that the cost of defluoridation can be reduced significantly and it can be used for a long time.