颗粒羟基氧化锆的除氟性能

Fluoride adsorption by granular hydroxyl zirconia

以羟基氧化锆粉末为原料,制备颗粒羟基氧化锆,评价了颗粒羟基氧化锆对溶液中F-的吸附性能。结果表明:颗粒羟基氧化锆除氟过程符合Freundlich吸附等温线模型和拟二级动力学模型,F-的吸附过程包括液膜扩散和颗粒内的孔扩散;pH在3～4时,颗粒羟基氧化锆的氟吸附量达到最大值27.72 mg/g,其他范围内pH的升高或降低都会导致氟吸附量的降低;Cl-对颗粒羟基氧化锆除氟过程无明显影响,而SO24-和PO34-对颗粒羟基氧化锆除氟过程影响较大,且浓度越高影响越大;扫描电镜和X射线能谱测试结果显示颗粒内随着颗粒深度的增加,F-含量逐渐降低,F-在颗粒内部的传质过程受到阻碍,SO24-和PO34-对颗粒羟基氧化锆除氟的干扰作用主要发生在颗粒表面。

The adsorbents of granular hydroxyl zirconia （GHZ） were prepared from the hydroxyl zirconia powder, and their properties of defluoridation were studied. The results showed that the F- adsorption of GHZ fitted better with Freundlich isotherm model than Langmuir model, and the kinetic data showed that it fitted pseu- do-second order model. The process of F- adsorption involved liquid membrane diffusion and intra-particle diffu- sion. The adsorption capacity of GHZ can reach the maximum value of 27.72 mg/g at pH from 3 to 4, which would decrease with the pH out of this range. Chloridion had no appreciable impact on the defluoridation process, but the F- adsorption was obviously influenced by sulfate ions and phosphate ions, and the higher the concentration the greater the effect. Scanning electron microscope and X-ray spectrometer showed that fluorine content gradually reduced along with the increase of depth of particles, which indicated that the mass transfer process of fluorinion inside the particle was blocked. SEM-EDS data also showed that the interference of sulfate ions and phosphate ions on defluoridation mainly occurred on the particle surface.