负载镧镁活性氧化铝的制备及除氟性能研究
RESEARCH ON PREPARATION AND FLUORIDE REMOVAL PERFORMANCE OF LANTHANUM-MAGNESIUM-LOADED ACTIVATED ALUMINA
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摘要: 采用浸渍法制备负载镧镁活性氧化铝改性除氟剂,用于去除溶液中氟离子。通过正交实验考察镧镁摩尔比、焙烧温度和焙烧时间对改性活性氧化铝吸附性能的影响,得出最佳合成条件为镧、镁物质的量比1∶2,焙烧温度300℃,焙烧时间2.0 h。研究吸附时间、投加量、p H值和共存阴离子对氟离子吸附效果的影响。结果表明:吸附时间为3.0 h、投加量为3.6 mg/L,p H值在6~9,除氟效果最好,氟离子去除率为94.5%;对比不同阴离子对除氟性能的影响,除氟性能受阴离子影响力大小为:CO2-3>SO2-4>Cl->NO-3;吸附剂对氟离子的吸附过程符合伪二级动力学模型,吸附等温线满足Langmuir吸附等温式,其饱和吸附量为7.663 mg/g;不同温度下的热力学结果表明该反应为自发吸热反应。Abstract: Lanthanum-Magnesium-loaded activated alumina prepared through impregnation was used to remove fluoride from aqueous solution. By orthogonal experiment,the paper studied effect of absorbability with La3 + /Mg2 + molar ratio,calcination temperature and calcination time. The optimum conditions were as follows: The molar ratio of La3 + to Mg2 + was 1 ∶ 2,the calcination temperature was 300 ℃,the calcination time was 2. 0 h. The influence of contact time,absorbent dosage,pH, and coexisted negative ions on fluoride adsorption were performed. Results showed that the optimum effect was contact time of 3. 0 h,absorbent dosage of 3. 6 mg /L,pH of 6 ~ 9, and the removal rate was 94. 5%. The influence of different anions on the adsorption was: CO2 - 3 > SO2 - 4 > Cl - > NO - 3 . Kinetic data were well described by the pseudo-second-order kinetic model. The adsorption isotherm could be well fitted by the Langmuir equation. The max adsorption capacity was 7. 663 mg /g. The results demonstrated that the adsorption process was spontaneous and endothermic.
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