农作物秸秆热解制备高效吸附材料及其对含氮废水的处理
毕业论文关键词：生物质炭；铵态氮；吸附；CEC
Efficient adsorption materials prepared by pyrolysis of crop straw and their use in treatment of wastewater containing nitrogen
Abstract: [Objectives]: The biochar adsorbents were prepared from crop straws, which provided a new method for treatment of swastewater containing nitrogen. [Methods]: Rice straw, maize straw and peanut straw were pyrolyzed under oxygen-limited conditions by muffle furnace at 300℃,400℃ and 500 ℃. An activated carbon and a zeolite were also used for comparison. The adsorption isotherms for NH+ 4 were investigated with a batch method, and the CECs of these adsorption materials were measured by a modified ammonium acetate compulsory displacement method. The wastewater containing ammonium nitrogen was obtained from nitrogen fertilizer plant, and biochars were used for purification treatment of the wastewater in order to verify the removal efficiency of ammonium nitrogen by the biochars. [Results]: Biochars had considerable CECs, and their CECs decreased with the increase of pyrolysis temperature, the CEC of the biochars decreased. In addition, the adsorption isotherms of ammonium on these biochars were fitted the Freundlich model well, which showed that the adsorption of NH+ 4 by the biochars from aqueous solution was dominated by heterogeneous multi-molecular layer adsorption. [Conclusions]: The biochars prepared by pyrolysis of crop straws can be used as an efficient adsorbents for ammonium in wastewater containing nitrogen.
Key Words:biochar;ammonium nitrogen;adsorption;CEC
目 录
摘要1
关键词1
Abstract1
Key words1
引言1
1材料与方法2
1.1 生物质炭的制备2
1.2 溶液的配制2
1.3 吸附实验2
1.4 生物质炭CEC的测定2
1.5 生物质炭改性处理2
1.6 实际含氮废水的处理3
2 结果与讨论3
2.1 不同热解温度下农作物秸秆生物质炭的产率3
2.2 生物质炭、活性炭及沸石的CEC3
2.3 沸石、活性炭及生物质炭对铵的吸附量4
2.4 吸附等温线拟合9
2.5 不同地区稻草秸秆生物质炭对铵的吸附量 10
2.6 改性前后生物质炭的Zeta电位 11
2.7生物质炭对实际含氮废水的处理 12
3 讨论13
3.1 结论 13
3.2 问题与展望 13
致谢13
参考文献14
农作物秸秆热解制备高效吸附材料及其对含氮废水的处理
引言:污水中氮的形态有四种，即有机氮、氨氮、亚硝酸盐氮和硝酸盐氮。其中，氨氮主要以游离氨态氮（NH3-N）和铵盐态氮（NH+ 4-N）的形式存在。水体中氨氮的来源有两个方面，一个是有机氮化合物的分解，另一个是工业含氮废水的排放。当氨氮大量进入水环境后，会消耗水体中的溶解氧，引起部分水生动物的死亡，导致水质迅速恶化；另外，它还会引起水体富营养化，促进藻类等浮游生物的繁殖，产生水华、赤潮等现象[1, 2]。因此，去除含氮废水中的氨氮是水环境治理过程中亟待解决的问题。目前，废水中氨氮常用的去除方法有化学沉淀法[3, 4]、离子交换法[4]、生物法[5]和吸附法[6]等。其中，吸附法的工艺较为简单，且具有高效、吸附剂可再生等优点，因而被广泛关注，而决定污水中氨氮去除效果的关键在于吸附剂的选择。