| 低氧烟道环境制备污泥活性炭 |
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| 引用本文： | 赵培涛,葛仕福,刘长燕.低氧烟道环境制备污泥活性炭[J].农业工程学报,2013,29(15):215-222. |
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| 作者姓名： | 赵培涛 葛仕福 刘长燕 |
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| 作者单位： | 1. 东南大学能源热转换及其过程测控教育部重点实验室，南京 2100962. 东京工业大学环境科学与技术系，横滨 226-8503;1. 东南大学能源热转换及其过程测控教育部重点实验室，南京 210096;1. 东南大学能源热转换及其过程测控教育部重点实验室，南京 210096 |
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| 基金项目： | 水体污染控制与治理科技重大专项（2010ZX07319-002）；江苏省2012环保科技计划（2012033）；国家建设高水平大学公派研究生项目（2011609050） |
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| 摘 要： | 为降低污泥制备活性炭的成本，以高温低氧烟道气为媒介，研究了活化时间、温度、蒸气含量以及氧含量对污泥活性炭性能的影响规律，结果表明：活化温度、活化时间及水蒸气流量的最佳值分别为800°C、90 min和34.8%，该条件下污泥活性炭比表面积、产率、甲基橙及亚甲基蓝吸附值分别为：246.3 m2/g、46%、14.8 mg/g、18.1 mg/g。因而，高温低氧烟气直接用于物理活化法制备污泥活性炭，活化气量（水蒸汽）不够，产品活性炭的性能差，活化温度高达800°C，运行成本仍偏高。将湿污泥用ZnCl2按1∶1浸渍16 h后活化炭化，在活化温度、活化时间、氧含量分别为550°C、90 min、2%时，污泥活性炭的产率为59%，其比表面积和亚甲基蓝吸附值分别达516.1 m2/g和129.8 mg/g，孔体积为0.29 cm3/g，微孔体积为0.16 cm3/g，平均孔径为3.95 nm，性能较好。氧气能促进活性炭微孔的形成与发展，最佳的氧含量为2%~4%。与无氧条件下制备的污泥活性炭相比，氧含量为4%时制得的污泥活性炭的比表面积增加了6.82%，亚甲基蓝吸附值提高了2.75倍。该研究表明：高温烟气作为热源、保护气和活化气，结合化学活化法，可将脱水湿污泥直接制成污泥活性炭。该结果可为低成本制备污泥活性炭、实现污泥处理的资源化利用提供一定的参考。
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| 关 键 词： | 活性炭，温度，吸附，物理活化，ZnCl2活化，高温低氧烟道气 |
| 收稿时间： | 2012/12/24 0:00:00 |
| 修稿时间： | 2013/4/26 0:00:00 |
Activated carbon production from sewage sludge employing low-oxygen flue gas |
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| Zhao Peitao,Ge Shifu and Liu Changyan.Activated carbon production from sewage sludge employing low-oxygen flue gas[J].Transactions of the Chinese Society of Agricultural Engineering,2013,29(15):215-222. |
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| Authors: | Zhao Peitao Ge Shifu and Liu Changyan |
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| Institution: | 1. Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast University, Nanjing 210096, China2. Department of Environmental Science and Technology, Tokyo Institute of Technology, Yokohama 226-8503, Japan;1. Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast University, Nanjing 210096, China;1. Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast University, Nanjing 210096, China |
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| Abstract: | Abstract: Sludge treatment and disposal have been a significant environmental problem because of the huge yield due to the high-speed urbanization and industrialization in China. Recently, in virtue of potential energy contained in organic matters of sewage sludge, thermal conversion technologies, such as pyrolysis, gasification, combustion and some high value-added products production, have been recognized as promising methods to deal with sludge aiming at energy recovering. Among them, sludge-derived activated carbon had been developed and worked as one of the most effective methods to realize the harmless sludge treatment and energy recycling simultaneously. However, the cost of the sludge-based activated carbon production was still high due to the huge amount of heat and gas required during the carbonization and activation. Therefore, this study proposed to produce the sludge-derived activated carbon with flue gases. The feasibility of exploiting low oxygen flue gas to prepare activated carbon from the sludge was investigated by focusing on the operating conditions, such as the activation method (physical activation and ZnCl2 activation), activation temperature, activation time, steam content, the ratio of sludge to ZnCl2 and oxygen content. The Brunauer-Emmett-Teller (BET) surface area and the adsorption value of the methylene blue and methyl orange of the derived activated carbon were taken as the indexes to evaluate its performance.The results showed that the optimal operating parameters of activation temperature, activation time and steam content were 800°C, 90 min and 34.8% respectively for the physical activation. However, the products were not so good comparing with the commercial products. The BET surface area, the yield of activated carbon, and the adsorption value of methylene blue and methyl orange were only 246.3 m2/g, 46%, 18.1 mg/g and 14.8 mg/g respectively. It was indicated that the single use of flue gas was not sufficient for physical activation of sludge to produce activated carbon due to its low vapor content and high operation cost to support the energy demands of high activation temperature. Some other activation method should be incorporated or modified to improve the thermal efficiency of this whole process as well the performance of sludge-based activated carbon.In respect to the ZnCl2 activation, the existence of oxygen can promote formation and development of the microspores of activated carbon. The BET surface area of the products produced under an oxygen content of 4%, was improved 6.82% comparing with what was prepared without oxygen. Correspondingly, the adsorption properties were improved with an increment of 2.75 times in the adsorption value of methylene blue. The optimal oxygen content was about 2%-4% for ZnCl2 activation. Under the optimal condition of activation temperature 550°C, activation time 90 min and oxygen content 2%, the yield of sludge-derived activated carbon as 59%; its BET surface area and methylene blue adsorption value were the highest of 516.1 m2/g and 129.8 mg/g, respectively; the pore volume, microspore volume and average pore size were 0.29 cm3/g, 0.16 cm3/g and 3.95 nm, respectively. All the data demonstrated that combination with chemical activation, the flue gas with high temperature and low oxygen content could be used as a heat resource, shielding gas and activation agent to produce activated carbon from dewatered sludge with moisture content higher than 80% directly. This study could provide a theoretical basis to lower the cost of sludge-derived activated carbon production from dewatered sewage sludge. It also provided a viable option to realize the harmless sludge treatment and cost-effective energy recycling simultaneously. |
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| Keywords: | activated carbon temperature adsorption physical activation ZnCl2 activation low oxygen flue gas |
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