利用高除污能力碳球用以吸附氮氧化物之研究

Preparation of Activated Carbon Sphere to adsorption NOX with high contaminant Removal EfficiencyEfficiency

林清濤(Cing-Tao Lin)

指導教授 ： 王雅玢 ； 游勝傑

中原大學/工學院/環境工程學系/碩士(2017年)

https://doi.org/10.6840/cycu201700639

摘要

氮氧化物可經由光化學反應而形成臭氧及光化學煙霧。此外，二氧化氮也會在空氣中氧化成硝酸與硝酸鹽，是造成酸雨的主因。活性碳為多孔性結構產物，具有高比表面積與不錯的吸附能力，目前廣泛應用於生活污水、工業污水、工廠廢氣及毒性氣體等淨化。
經SEM及BET分析結果可知，以葡萄糖作為活性碳之製備原料可獲得表面平整且光滑的碳球結構，在添加K2CO3活化後，可使活性碳具有更良好的孔隙度(孔徑約2.03 nm)及比表面積(1,181.5 m2/g)。另依粒徑分析結果來看，約有35%介於0.149~0.25 nm，約有50%介於0.106~0.149 nm，另約有15%小於0.106 nm。
在固定NOX濃度1,000 ppb下，利用3,000 ml/min、2,000 ml/min、1,000 ml/min等三種流量進行測試，係以最低流量1,000 ml/min的表現最佳，其最佳吸附濃度約490ppb，直至72小時，其濃度約達752ppb，仍未達飽和濃度。另在吸附量表現上，同樣以流量1,000 ml/min的表現最佳，24小時內累積吸附量可達364mg/g以上。
再生後活性碳在NOX濃度1,000 ppb與流量為3,000 ml/min下，直至24小時內其濃度仍可維持在890ppb，且其累積吸附量可達355mg/g。
此外，在NOX濃度1,000ppb及流量3,000 ml/min的測試環境下，市售活性碳的最佳吸附濃度約798ppb，飽和濃度到達時間約9小時，24小時累積吸附量約86mg/g；而本研究活性碳的最佳吸附濃度約730ppb，飽和濃度到達時間約19小時，24小時累積吸附量約268mg/g。兩者相較下，本研究活性碳之整體吸附能力遠高於市售活性碳。
由碘值分析結果來看，本研究自製活性碳之碘值約為2,291mg/g，若與台灣南部6座垃圾資源回收(焚化)廠粉狀活性碳之碘值的採購規格(600~1,250mg/g)相較下，本研究自製活性碳之碘值吸附能力則明顯優異許多。
由各不同流量之測試結果來看，本研究的實驗流速太快且滯留時間太短，而無法更有效呈現出本研究所製備之活性碳的最佳吸附效益。

關鍵字

氮氧化物 ； 水熱合成法 ； 活性碳 ； 吸附

並列摘要

Photochemical smog were formed when emissions containing nitrogen oxide, such as car exhaust, interact with volatile organic compounds in the presence of sunlight. The ground-level ozone were formed by the combination of oxygen in the compounds and the heat from the sunlight. Also, acid rain was formed by the combination of nitrogen dioxide and sulfite with moisture in the atmosphere, and were lead nitric and sulfuric acids. Activated carbon is a form of carbon processed to have small, low-volume pores that increase the surface area available for adsorption or chemical reactions. Active carbon adsorption has numerous applications in removing pollutants from air or water streams both in the field and in industrial processes such as: Drinking water filtration and Air purification.
In this study, the activated carbon with a smooth and smooth carbon ball structure can be obtained by using glucose as the raw material for the preparation of activated carbon. As a result of SEM and BET analysis shows the process of making activated carbon K2CO3 activation, might lead the activated carbon got a better porosity(pore size about 2.03 nm) and specific surface area (1,181.5 m2/g). According to the results of particle size analysis of activated carbon, about 35% of activated carbon is between 0.149 and 0.25 nm, and about 50% of activated carbon is between 0.106 and 0.149 nm, and about 15% of activated carbon less than 0.106 nm.
The NOx adsorption capacity of activated carbon was measured by three flow rates of 3,000 ml / min, 2,000 ml / min, and 1,000 ml / min at a fixed NOX concentration of 1,000 ppb. In the experiment of adsorption concentration, the lowest flow rate of 1,000 ml / min of the best performance, and the adsorption concentration of 490 ppb, after 72 hours its concentration was 752 ppb, may still not reach the saturation concentration. In addition, the adsorption capacity of as-prepared material was same as the flow of 1,000 ml / min were best performance in 24 hours cumulative adsorption capacity of up to 364 mg / g or more. However, under the experimental conditions NOX concentration of 1,000 ppb and flow rate of 3,000 ml / min. After the regeneration of activated carbon, its effect of adsorption can still maintain about 890ppb after 24, and the cumulative adsorption capacity of 355 mg / g.
In addition, the adsorption capacity of activated carbon and commercially available activated carbon for NOX was compared with that in the same NOX concentration of 1,000 ppb and flow rate of 3,000 ml / min. The results show that the optimum adsorption concentration of commercially activated carbon was 798 ppb, the saturation time was 9 hours, and the cumulative adsorption capacity was 86 mg / g after 24 hours; On the other hand, the optimum adsorption concentration of as-prepared activated carbon was 730 ppb, the saturation time reached was19 hours, and the cumulative adsorption capacity was about 268 mg / g after 24 hours. The overall adsorption capacity of activated carbon in this study was much higher than commercial activated carbon.
From the iodine value analysis results, the study of self-made activated carbon iodine value of about 2,291mg / g. Compared with the purchase standard (600 ~ 1,250mg / g) of the six kinds of powdered activated carbon in the garbage collection (incineration) plant in the south of Taiwan, the iodine value of the self-made activated carbon is obviously superior. The experimental results show that the experimental flow rate was too fast and the residence time was too short to show the best adsorption benefit of as-prepared activated carbon.

並列關鍵字

Nitrogen Oxides ； Hydrothermal Synthesis ； Activated Carbon ； Adsorption

參考文獻

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