【作者】 杜俊逸；

【导师】 吴代赦；

【作者基本信息】 南昌大学 ， 环境科学， 2010， 硕士

【摘要】 为了研究粘土矿物吸附氟后的表层形态变化和反应机制,四种粘土矿物(高岭石、蒙脱石、绿泥石、伊利石)浸泡在高氟浓度溶液(5-1000 mg/L)和低氟浓度溶液(0.3-1.5 mg/L)进行吸附实验,并利用X射线光电子能谱进行表面形态分析。粘土矿物在高氟浓度溶液吸附时,溶液平衡氟浓度、吸附量、溶液pH和释放羟基量随氟浓度增加而增加；而且吸附量在50/100 mg/L以上时显著增加。用酸碱调节维持氟溶液pH时,粘土矿物氟吸附量增加。各浓度浸泡后吸附数据和氟电子能峰位表明：粘土矿物在氟浓度溶液小于5～100 mg/L时预先吸附氢离子使表面活性位质子化,然后与氟发生交换；随氟浓度升高,氟直接交换铝活性位羟基,并且与其它阳离子结合；而在氟溶液浓度大于100 mg/L时生成冰晶石(及氟化铝)沉淀。粘土矿物在高氟浓度溶液吸附时生成的新矿物与溶液铝离子浓度有关,铝离子浓度大于10-11.94mol/L生成冰晶石沉淀,铝离子浓度小于10-11.94mol/L生成氟化铝沉淀。粘土矿物在低氟浓度溶液吸附时会发生质子迁移现象,这使得溶液氟浓度随时间推移持续降低。研究了硫酸铝浸渍活性氧化铝球(AIAA)处理高氟水的能力。静态实验通过改变吸附剂量(2-40 g/L)、氟浓度(2-100 mg/L)、pH(4-10)、温度(11-33℃)、时间,研究这些因素对吸附过程的影响。动态柱实验研究氟浓度(10-50 mg/L)、流速(2-10mL/min)、填料高(10-20 cm)三个操作参数对柱除氟性能的影响。当温度11-33℃、pH4-10、吸附剂量20g/L时,AIAA 3h内处理10 mg/L氟溶液效率可达90%以上,少量阴离子的共存对氟离子的吸附没有影响。吸附平衡拟合模型表明低浓度氟溶液的吸附中,Langmuir模型线性拟合或非线性拟合是最优拟合方式；而高浓度氟溶液的吸附中,Freundlich模型非线性拟合是最优拟合方式。热力学研究表明AIAA吸附主要为化学吸附；动力学研究表明吸附速度受表面扩散控制,吸附反应更符合二级动力学。动态柱实验中降低流速、增加填料层高度可以提高除氟效果。0.1M NaOH再生效果良好,三次更换再生液基本可以完全解吸。更多还原

【Abstract】 Kaolinite (K), Montmorillonite (M), Chlorite (Ch), Illite (I) are four representative clay minerals in nature which are selected as research objects. This research investigates fluoride (F-) adsorption mechanism onto four kinds of clay minerals under different pH, F- concentration and reaction time, and studies superficial layers morphology of F as well as elements composition by X-ray photoelectron spectroscopy (XPS) analysis. In high F- concentration(Co) solution (5-1000 mg/L), F-adsorption amount(QF), hydroxyl release amount(HRA) of clay minerals, equilibrium F- concentration(CF) and equilibrium pH increase with increasing Co, especially remarkably when above 50 mg/L. And by modifying and maintaining solution pH at 6, F- adsorption amount of clay minerals is higher than that without pH regulation. Various adsorption data and F- binding energy of superficial layers (FSBE) detected by XPS indicate that at Co less than 5-100 mg/L clay minerals firstly adsorb H+ to protonate aluminum active hydroxyl sites (AAHS) in superficial layers, and react with F-; and as Co gradually increases clay minerals can adsorb F- directly together with the adsorption of some cations; and at Co greater than 100 mg/L F- precipitates in the forms of cryolite or AIF3. The type of new minerals formed in superficial layers in high Co solution depends on Al3+ concentration (CAl)-cryolite at CAl greater than 10-11.94mol/L, AIF3 at CAl less than 10-11.94mol/L. In low CO (0.3-1.5 mg/L) solution proton transfer occurs to make CF decrease continuously with passing of time.The second chapter research the defluoridation capacity of aluminum sulfate impregnated alumina granule (AIAA) in treating high fluoride water. Batch experiments study the influence of operational factors on fluoride adsorption by varying adsorption amount (2-40 g/L), fluoride concentration (2-100 mg/L), pH (4-10), temperature (11-33℃), time. Column experiments study the influence of fluoride concentration (10-50 mg/L), flow rate (2-10 mL/min), filler height (10-20 cm) on defluoridation capacity of AIAA column. At 11-33℃, pH 4-10 and adsorbents amount 20 g/L, the efficiency of AIAA treating 10 mg/L fluoride solution in 3 h is more than 90%, and the existence of a little amount of anions do not influence fluoride adsorption. The study of adsorption equilibrium fitting models illustrate that Langamuir model linear fitting is the optimistic fitting method when AIAA in low fluoride concentration solution; while Freundlich model non-linear fitting is the optimistic fitting method when AIAA in high fluoride concentration solution. Thermodynamic studies show that chemical adsorption plays the dominant role of fluoride adsorption by AIAA; kinetic studies show that adsorption rate is controlled by surface diffusion process and adsorption reaction tallies with pseudo-second order kinetics. In column experiments, lowering flow rate or increasing filler height can improve defluoridation efficiency. In regeneration process,0.01 M NaOH has the best regenerated effect which can regenerate saturated AIAA completely by three times renewing.更多还原