https://scholars.lib.ntu.edu.tw/handle/123456789/77010
標題: | 以微波輔助重金屬污泥回收再利用之研究 Microwave Enhanced Reclamation of Heavy Metal Sludge |
作者: | 謝慶弘 Hsieh, Ching-Hong |
關鍵字: | 重金屬污泥銅;微波;安定化;吸附;Heavy metal sludge;Copper;Microwave;Stabilization;Adsorption | 公開日期: | 2008 | 摘要: | 重金屬污泥在台灣為一產量甚大的有害事業廢棄物,其中以含銅污泥產amp;#63870;為最大宗。若未加以處理而棄置,則會造成土壤及地下水的污染並危害人健康。本研究嘗試以微波輻射程序進行重金屬污泥之安定化,期望達到無化及資源化之目標。驗中探討之影響因子為:微波誘發程序影響、安定劑劑量與種類、微時間及功率、反應氣氛、微波吸收質、微波混成程序及溫度之影響。除了討其重金屬溶出濃度及安定化效率,並研究其固相化學反應。而安定化污amp;#63971;亦進行資材化之研究,探討其對於金屬離子的吸附性質與吸附量。果顯示不同的處理程序當中,以同時添加還原性金屬安定劑並供給微輻射方能有效達到含銅重金屬污泥之安定化,且還原性金屬添加劑量與該amp;#63754;屬之反應性成反比。當微波功率越強或微波時間越長時都有較佳之安定化果。但在高功率微波照射下,樣品間會產生較大之之熱壓力造成顆粒之間裂隙進而降低安定化的穩定性。無添加安定劑時,以空氣做為反應氣體及冷卻氣體(Air/Air)會造成污amp;#63971;中的有機物完全燃燒並使銅大量溶出;而填充氮氣(N2/N2)則能阻隔有機物氧氣接觸,因此銅溶出濃度較低。若同時添加安定劑與控制反應氣氛,實污泥填充氮氣(N2/N2)能有效的增進安定化效率,縮短安定化所需的時間;amp;#63860;配合空氣進行冷卻(N2/Air),則可使高能鋁粉氧化釋出氧化熱,促成銅物脫水反應及CuO 的生成。而無機污泥(De10)方面,在(Air/Air)環境鋁粉會漸釋出氧化熱,安定化效率會逐漸上升;而N2/N2 組電弧程序的產生應為要污泥安定化的方式。在微波程序中,有機物的悶燒與否將微影響污泥安定化之穩定性。但amp;#63860;污泥中的有機物及水分一併去除而僅添加安定劑,則會使得安定化效果不V。當添加吸收微波能力較強的微波吸收質於污泥中時,微波安定化之效率明顯的提升。而在銅污泥安定時卻造成Al 及Fe 的溶出濃度增加,可能是l0 可在微波提供能量的狀況下,直接或間接將Fe3+及Cu2+還原成Fe2+ (或其溶解性較高的鐵氧化物)及Cu0 或CuO,而本身則氧化為Al3+。微波混成程序中添加活性碳收並控制反應環境(N2/N2),仍能達到安定之效果;安定化反應包括脫水反應、物種轉換、玻璃化、還原反應及硫化生成。高溫固相化學反應方面,當溫度高達900 ℃時,CuAl2O4 有較高的換率。當混合Cu4SO4(OH)6 與α-Al2O3 進行高溫鍛燒時,顯示溫度升高有於CuO 的生成,但是CuO 與α-Al2O3 的顆粒可能只在表面層生成uAl2O4,因此無法明確地以XRD 鑑定。以CuO 與α-Al2O3 混合,反應轉換amp;#63841;不高;若以CuO 與γ-Al2O3 混合,在800 ℃有大量CuAl2O4 生成,因為-Al2O3 有較鬆散之結晶結構,有助於CuO 與γ-Al2O3 嵌合及CuAl2O4 生成。材化研究方面,當溶液的pH 範圍在2-11 之間時,安定化污泥表面的荷皆為負電,因此適合作為陽離子之吸附劑。動力學研究中,吸附實驗數較符合pseudo-second order model,顯示銅離子與安定化污泥之間的吸附視為一種活性吸附機制。而等溫吸附實驗(Isotherm)數據與Langmuirquation 有較高的相關係數。從熱力學的參數中可得知銅離子於安定化污泥面的吸附為吸熱反應。但是整體的吸附現象確有可能包含物理性及化學性附。而銅離子於安定化污泥表面的吸附容量分別約為23 mg/g (SL07-FeA)15.5 mg/g (SL07-AlA), 此吸附容量大於許多其他固體廢棄物吸附劑的吸容量。因此安定化污泥可被應用於含重金屬廢水吸附的資材化物質。 The leaching concentration of heavy metal sludge is above the TCLPriteria for land disposal (< 15 mg/L) and regarded as a hazardous solid waste.ithout proper treatments, the hazardous sludge would contaminate the soil andround water and even human health. Therefore, a stabilizing process for theremendous amount of heavy metal sludge is required before land disposal andeuse. In this study, microwave processes were conducted for the stabilization ofeavy metal sludge. The effects different processes, stabilizing agents, processime, microwave power, reaction atmosphere, microwave adsorbents, microwaveybrid process and temperature variation were investigated. The solid stateeaction and adsorption study of stabilized sludge were also discussed.esults indicated that better stabilization ratio was reached when microwaveadiation was applied coincided with the addition of reductive metal powder. Thedding dose of metal powder at same stabilization ration was in reverse order ofetal reactivity. As copper was stabilized, Fe and Al also leached out duringCLP process. Al3+, Fe2+ and Cu0 (or CuO) was formed as redox reaction wasccurred. The stabilization efficiency improved at higher microwave power, buthe thermal pressure caused by higher microwave power could decline theIeproducibility of experimental data. For raw heavy metal sludge (TD10), theludge would smolder under oxygen atmosphere leading to the leaching of metalons when only microwave radiation was applied. Moreover, as microwaveadiation was served coupled with stabilizing agent to TD10, an inert reactiontmosphere (N2) during heating and oxidizing atmosphere (air) for cooling gaveetter performance. Oxidation heat released from the oxidation of aluminumowder may be attributed to the formation of CuO. When metal powder wasdded into inorganic sludge (De10) with microwave radiation at N2/N2, theicroarcing process may be responsible for the dehydration reaction of sludge.ppropriate amounts of microwave adsorbents in the sludge would increasehe homogeneity of microwave energy to increase the reactions betweentabilizing agents and copper. In Hybrid Microwave process, when processingime was longer than 18 min and AC dosage was more than 3 g, a minor portionf the De10 was vitrified and leading to low copper leachability. Addingarbonaceous materials in the samples would enhance the transformation ofopper into CuAl2O4 due to the additional burning heat. Also, in this process, theeduction reaction may be attributed to the formation of Cu2S. In the solid stateeaction, the transformation of CuAl2O4 was higher at 900 ℃. Calcination ofixture of CuO and γ-Al2O3 gave better transformation ratio of CuAl2O4 whenIIompared with mixture of CuO and α- Al2O3. The diffusion rate of solid particles,ormation of surface layer, lattice structure, and amorphous intermediate productay be attributed to the differences of transformation ratio.n the adsorption study, the surface charge of stabilized-sludge was negativet the pH range of 2-11. The removal of copper ions increased as the initial pHose, and the final pH maintained at a constant of pH 7.2 while the initial pH isrom 6 to 8. In the kinetic study, the adsorption of copper ions onto adsorbentas fitted to the pseudo-second order model with great correlation coefficient (R2 0.994). This result shows the adsorption of copper ions onto stabilized-sludgeo be an activated adsorption mechanism. The experimental data was alsonalyzed by the isotherm equations and correlation coefficient of the Langmuirquation was better than that for the Freundlich equation. In isotherm experiment,oth the Q0 and b increased as the temperature ure rose from 15℃ to 55℃. Thismplies that this adsorption reaction was an endothermic reaction which can alsoe demonstrated by the thermodynamic study with the parameters, ΔG0, ΔH0 andS0. The adsorption capacity of copper ions onto stabilized-sludge was around5-23 mg/g, which was greater than that on many other solid wastes. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/181525 |
顯示於: | 環境工程學研究所 |
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ntu-97-D92541006-1.pdf | 23.53 kB | Adobe PDF | 檢視/開啟 |
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