【作者】 单悦；

【导师】 郭华明；

【作者基本信息】 中国地质大学（北京） ， 地下水科学与工程， 2014， 博士

【摘要】 众所周知，氟是人体健康不可缺少的元素，但过量的摄入氟能导致氟中毒。在众多除氟技术中，吸附法一直被广泛关注。虽然有些吸附剂具有良好的除氟性能，但它们主要作为粉末状存在，大大限制了在实践中的应用。为了克服这些缺点，本论文研究一种以天然菱铁矿为骨架的新型颗粒状除氟吸附剂。本文研制了硫酸铝和铝溶胶联合改性天然菱铁矿（AMNS）。通过批实验，探讨了初始氟浓度、接触时间、共存阴离子和温度等因素对AMNS除氟性能的影响。AMNS的除氟容量是未改性天然菱铁矿的7.5倍，吸附过程符合伪二级速率方程。AMNS吸附氟是自发吸热反应。HCO3-或PO43-对氟吸附有明显的负面作用，而Cl-、SO42-和NO3-对氟吸附无显著抑制作用。通过优化天然菱铁矿、硫酸铝和铝溶胶的混合比、灼烧温度和时间，进一步优化吸附剂的除氟性能，得到最优除氟吸附剂（OMNS）。溶液pH值在3.5-10.0之间对氟去除率没有明显影响。动力学结果表明，氟离子吸附遵循二级动力学方程。外扩散和内扩散同时促进了氟的吸附。柱实验表明，在进水氟浓度和流量较高的情况下，吸附柱的除氟容量较低。通过X射线衍射研究表明，氟离子吸附主要是由于改性材料中赤铁矿和γ-氧化铝的形成。此外，研制了硫酸铝、膨润土和可溶性淀粉联合改性天然菱铁矿（ABS-NS），并表征了其除氟性能。溶液pH值在5-7之间时，保持比较高的除氟容量。吸附过程符合二级动力学模型，内扩散不是控制吸附速率的决定性因素。热力学数据表明，氟的吸附是自发吸热反应。阴离子在溶液中与氟离子共存时,对ABS-NS吸附氟的影响程度依次为PO43-> HCO3-> SO42-> Cl-> NO3-；As(V)、Ca2+和Mg2+的存在，对氟离子的吸附起促进作用。选取昌平小汤山苗圃高氟地下水为原水，利用灼烧-浸泡方法改性天然菱铁矿（CS-NS）进行中试除氟试验。结果表明，调节进水pH能显著提升CS-NS除氟容量。单柱运行，调节进水pH，合格出水量是未调节进水pH时的6.5倍；双柱串联运行，调节进水pH，处理的合格水量是两柱串联未调节进水pH时的6.7倍。吸附柱再生三次后，吸附柱仍有较高的除氟性能。更多还原

【Abstract】 It is well known that fluoride is an indispensable element for human health, butexcessive fluoride intake can result in endemic fluorosis. Adsorption is believed to be agood technology for fluoride removal from water solution, which has been receivedmuch attention. Although many adsorbents had good fluoride adsorption capacities,most of them were commonly fine powders, leading to the limitation in practicalapplication. To overcome these limitations, this study has developed a novel granularadsorbent for defluoridation using natural siderite.Aluminum modified granular natural siderite (AMNS) was fabricated for fluorideremoval from drinking water. Effects of initial fluoride concentration, contact time,coexisting anions, and reaction temperature on F-adsorption on AMNS wereinvestigated. Adsorption capacity of AMNS was7.5times higher than pristine naturalsiderite. Adsorption closely followed the pseudo-second-order rate equation. Fluorideadsorption on AMNS was reasonably spontaneous and endothermic. Moreover, it wasobserved that the coexistence of HCO3-or PO43-negatively affected F-removal, whileCl-, SO42-, and NO3-had no significant effect on fluoride adsorption.The modified natural siderite was fabricated for F-removal by optimizing themixing ratio of natural siderite, Al2(SO4)3, and AlOOH, calcination temperatures andtime durations, and the optimaized adsorbent was obtained.(OMNS). Solution pH hadno significant effect on F-removal between3.5and10.0. Kinetic results showed thatadsorption followed the pseudo-second-order kinetic equation. Both the externaladsorption and the intra-particle diffusion contributed to adsorption processes.Thermodynamic data showed that fluoride adsorption was reasonably spontaneous andendothermic. Moreover, fluoride adsorption was obviously constrained by thecoexistence of HCO3-and PO43-. Column studies revealed that breakthrough time andadsorption capacity were lower at the higher F-concentration and/or higher flow rate.The XRD analysis indicated that the uptake of fluoride attributed to the coexistence ofhematite and γ-Al2O3in the modified material. In addition, aluminum, bentonite and soluble starch were used to modify naturalsiderite (ABS-NS) for fluoride removal from drinking water. Solution pH had nosignificant effect on F-removal between5and7. Adsorption closely followed thepseudo-second-order rate equation, which indicated that both external mass transferand intra-particle diffusion controlled F-adsorption. Thermodynamic data showed thatF-adsorption was reasonably spontaneous and endothermic. Effects of co-existinganions on fluoride adsorption followed: PO43-> HCO3-> SO42-> Cl-> NO3-. Thepresence of As(V), Ca2+and Mg2+promoted fluoride adsorption on ABS-NS.Pilot test was conducted at Changping Xiaotangshan nursery to remove F-fromhigh F-groundwater, using calcination-soaked modified natural siderite (CS-NS).Influence of solution pH was significant for fluoride removal. In single column withadjusted pH around6.5in influents, fluoride adsorption capacity is6.5times higherthan that pristine groundwater as influents (pH=7.79). In double-column series withadjusted pH around6.5in influents, fluoride adsorption capacity is6.7times higherthan that pristine groundwater as influents (pH=7.79). Adsorbent still showed highadsorption capacity after three regeneration cycles.更多还原