| 摘要: | 本研究主要探討利用下水污泥與淨水污泥灰作為碳及矽、鋁源，以鹼熔與水熱兩階段程序合成活性碳-沸石複合吸附材料，並藉由有機及無機污染物吸附試驗來評估其作為環境淨化資材之可行性。複合吸附材料製備過程是以混合不同比例之下水污泥與淨水污泥灰，來配置污泥原料中之Si/Al莫耳比與碳含量，進而探討其對複合吸附材料中沸石結晶物種之影響。實驗結果證實影響沸石結晶物種之主要因子為原料之Si/Al莫耳比。下水污泥與淨水污泥灰之混合比例1:9之原料理論Si/Al為1.57，所製備出複合材料ACZ1090為低活性碳含量之純相Na-A型沸石；而混合比例為3:7之ACZ3070與5:5之ACZ5050原料之理論Si/Al分別為1.72與1.93，所製備出之兩複合材料活性碳含量則分別為2.75 %及4.14 %，而主要沸石結晶物種皆為Na-X型沸石。等溫吸附試驗結果，發現三組以不同混合比例之水處理污泥所製備出的活性碳-沸石複合吸附材料ACZ1090、ACZ3070及ACZ5050個別吸附MB、Cu(II)、Cd(II)皆符合Langmuir模式，而複合吸附材料ACZ1090對MB、Cu(II)及Cd(II)之最大吸附量依序為0.10、0.68、0.49 mmole/g；ACZ3070為0.11、0.64、0.50 mmole/g；ACZ5050則為0.14、0.56、0.45 mmole/g。而在多成份污染物吸附試驗發現三組以水處理污泥為原料所製備出的複合吸附材料對污染物之吸附選擇性順序為Cu(II)>Cd(II)>MB。最後，比較市售沸石與自製複合吸附材料之污染物去除能力，確定以水處理污泥所製備出之活性碳-沸石複合吸附材料具有一定之污染物去除效力，確實可作為環境淨化資材。 This study investigated the feasibility of synthesizing activated carbon-zeolite composites (AC-Z composites), using primarily sewage and water purification sludge as starting silicon, aluminum and carbon sources; and the AC-Z composites as synthesized in this study were evaluated for their adsorption behavior of Cd, Cu and methylene blue (MB), in hope that such composites could be applied to remove organic and inorganic pollutants simultaneously. Firstly, the starting sludges as received were pretreated by drying and/or incineration to provide the dry sewage sludge (DSS) and the water purification sludge ash (WPSA), respectively, for the subsequent study. Secondly, it is supposed that the silicon and aluminum sources are provide by both DSS and WPSA, and the carbon source solely by DSS, and that the molar ratio of Si/Al and carbon content can affect the synthesis of zeolite and production of activated carbon; therefore, starting materials with various Si/Al ratio and carbon content were prepared by a mix design of DSS and WPSA (i.e., DSS:WPSA=1:9, 3:7 and 5:5). Thirdly, the synthesis of AC-Z composites were conducted by an alkali fusion, followed by a hydrothermal process. The results indicate that the resultant ACZ1090 composite ( i.e., DSS:WPSA=1:9 for the starting mixture) was confirmed to contain trace amount of activated carbon and single-phased Na-A zeolite as main phase; in contrast, ACZ3070 composite, 2.75% activated carbon and Na-X zeolite as main phase; and ACZ5050 composite, 4.14% activated carbon and Na-X zeolite also as main phase. The results suggest that the activated carbon content in the resultant composites increased with increasing mix portion of DSS; and the theoretical Si/Al ratio of the starting mixture increased with the increasing portion of DSS (i.e., from 1.57 to 1.93), it seemed that with the increasing Si/Al ratio, the main crystal phase of in the resultant composites shifted from Na-A type to Na-X type. The resultant AC-Z composites were evaluated for their adsorption of MB, Cu(II) and Cd(II). The adsorption of MB, Cu(II) and Cd(II), respectively, in a single component system, was found well fitted with the Langmuir model. The maximum adsorption of MB, Cu(II) and Cd(II), in a single component system was found to be 0.10, 0.68 and 0.49 mmole/g, respectively for ACZ1090 composite; and in comparison, 0.11, 0.64 and 0.50 mmole/g, respectively, for ACZ3070 composite; and 0.14, 0.56 and 0.45 mmole/g, respectively, for ACZ5050 composite. All the adsorption performance was comparable to that of the commercial grade 4A zeolite and 13X zeolite. However, the adsorption of MB, Cu(II) and Cd(II), in a multi-component system showed decreased adsorption quantity for the tested adsorbates, possibly due to the competition among the adsorbates. It was found that the selectivity for the tested adsorbates in decreasing order was Cu(II)>Cd(II)>MB. This work demonstrated that it is feasible and beneficial to synthesize activated carbon-zeolite composites (AC-Z composites) with primarily sewage and water purification sludge as starting silicon, aluminum and carbon sources. The results may contribute to the recycling of water treatment sludges and the production of green activated carbon-zeolite composites. |
