【作者】 刘晶；

【导师】 刘福强；

【作者基本信息】 南京大学 ， 环境工程， 2011， 硕士

【摘要】 我国高氟地下水分布很广,遍布27个省、市、自治区,致使华北、西北等干旱半干旱地区饮用高氟水的人较多,危害严重。同时,橡胶、肥料、半导体、玻璃、陶瓷、电镀、矿山开采、制药等行业排放出的含氟废水对生态环境带来明显的污染破坏。因此,除氟技术研究一直是国内外环保领域的热点课题之一。本论文采用自主合成的改性树脂作为除氟材料,并利用红外光谱、比表面积、孔结构、电子能谱等方法对其理化结构进行分析表征,并系统研究了其对低浓度氟离子的吸附特性及作用机理,从而为含氟废水的深度处理探索新途径。选择苯乙烯-二乙烯苯共聚物(NDA-1800、XAD-4、NDA-150)为母体,采用硝化-胺化、磺化-载金属及硝化-磺化-胺化-载金属等反应制得系列不同功能基的除氟树脂,通过静态吸附实验筛选出吸附容量大的氨基改性树脂、氨基改性及金属负载树脂进行结构分析,改性前NDA-1800和XAD-4树脂以中孔为主,NDA-150树脂以微孔为主,改性后树脂孔径均有所降低。系统考察了不同改性树脂对低浓度氟离子的吸附特性。氨基改性树脂(NDA-1800-NH2、XAD-4-NH2、NDA-150-NH2)的静态吸附等温线能用R-P方程进行较好的描述,热力学结果表明该反应是自发进行的放热反应。动力学实验结果符合二级动力学方程,三种改性树脂对氟离子的Qe顺序为NDA-1800-NH2 >XAD-4-NH2>NDA-150-NH2。动态穿透吸附曲线符合Thomas模型和Y-N模型,以出水为1mg/L为穿透点,NDA-1800-NH2、XAD-4-NH2、NDA-150-NH2的穿透时间分别为11h、9h、4h,进一步证明了NDA-1800-NH2的优越性。将氨基改性后的树脂负载金属制得系列复合功能除氟材料(NDA-1800-N-S-Fe、XAD-4-N-S-Fe、NDA-150-N-S-Fe),静态吸附等温线能用Langmuir方程进行拟合,热力学结果表明该反应是自发进行的吸热反应。动力学实验结果符合二级动力学方程,三种改性树脂对氟离子的吸附量顺序为NDA-1800-N-S-Fe<XAD-4-N-S-Fe<NDA-150-N-S-Fe.动态穿透吸附曲线符合Thomas模型和Y-N模型,以出水为1mg/L时为穿透点,NDA-150-N-S-Fe、XAD-4-N-S-Fe、NDA-1800-N-S-Fe树脂的穿透时间分别为26h、24h、23h。通过对改性树脂吸附氟离子前后的FT-IR及XPS分析可知,氨基改性树脂对氟离子的吸附主要是物理作用,即质子化的氨基与氟离子之间的静电作用。孔结构也对吸附性能有一定的影响,孔径越大,负载的氨基含量越多,从而引起吸附量的增加。同时粒径在动态吸附过程中发挥了重要作用,粒径越小,传质速率越快,吸附容量越大。氨基改性及金属负载树脂对氟离子的吸附主要以化学作用为主,即铁离子与氟离子之间的络合作用,同时NDA-1800上氨基与氟离子之间的物理作用表观较明显。更多还原

【Abstract】 In our country, ground water with high concentration of fluoride is widely distributed in 27 provinces, municipalities or autonomous regions. In arid or semiarid areas of north and northwest China, a large number of people drink water containing high concentrated fluoride which poses a significant health hazard. At the same time, high-concentrated fluoride effluent from rubber, fertilizer, semiconductor factories, glass, ceramics, electroplating industries, mine or pharmaceutical industries has caused serious impact on ecological environment. Therefore, research on available techniques for the removal of fluoride has been a very hot topic in the realm of environmental protection at home and abroad. In this paper, several kinds of resins synthesized by using new methods were used to remove fluoride in the aqueous media. IR-FT, SEM, Pore Structure and XPS were used to characterize the structure and properties of the resins. The mechanism for the removal of fluoride has also been discussed. The object of current study aims at exploring a new way to the deep removal of fluoride.Series of differently functional resins were synthesized by nitration-amination, sulfonation-metal supporting, and nitration-sulfonation-amination-metal supporting, using styrene-divinylbenzene polymer (NDA-1800, XAD-4, NDA-150) as matrix. Amino modified resins and amino modified-metal ion supported resins, which had large adsorption capacities, were chosen by adsorption isotherms to study the structure. The result shows that mesopores were dominant for NDA-1800 and XAD-4 modified resins, while micropores for NDA-150.The adsorption performance of the modified resins was also studied. Adsorption isotherms of the amino modified resins indicated that R-P model fitted better with the experimental data than Langmuir and Freundlich isotherm. The values of thermodynamic parameters confirmed that the fluoride sorption was spontaneous and exothermic. The kinetic curves and obtained adsorption rate followed the pseudo-second-order better and Qe followed NDA-1800-NH2>XAD-4-NH2> NDA-150-NH2. Thomas and Y-N model could be used to predict the breakthrough point in the column adsorption. The breakthrough time of NDA-1800-NH2, XAD-4-NH2 and NDA-150-NH2 were 11h,9h and 5h, respectively, when using 1mg/L as the effluent concentration.Series of compound functional materials (NDA-1800-N-S-Fe、XAD-4-N-S-Fe、NDA-150-N-S-Fe) to remove fluoride were synthesized by supporting metal to the amino modified resins. Static adsorption isotherms fitted Langmuir model better. Thermodynamic parameters showed that the reaction was also spontaneous and exothermic. The date of dynamic experiment also followed the pseudo-second-order The adsorption capacity of the above three resins followed the order: NDA-1800-N-S-Fe<XAD-4-N-S-Fe<NDA-150-N-S-Fe. Thomas model and Y-N model could also be used to predict the breakthrough point in the column adsorption As lmg/L the penetration point, the breakthrough time was 26h,24h and 23h for NDA-150-S-N-Fe, XAD-4-N-S-Fe, and NDA-1800-N-S-Fe, respectively.FT-IR and XPS indicated the physic-sorption such as electrostatic attraction between the protonated amine and fluoride. Pore structure and granularity played important part in the adsorption of fluoride. As for amino modified-metal ion supported reins and fluoride, chemical adsorption was dominant. Fluoride was adsorbed by complexion formation of iron. The physical interaction between fluoride and the amino groups on NDA-1800 was also distinct.更多还原