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The activation regeneration of spent diatomaceous earth for manufacturing porous materials
Spent diatomaceous earth
|上傳時間: ||2008-10-08 15:45:30 (UTC+8)|
本研究之目的乃利用一套仿旋轉窯爐之水平式旋轉反應爐於不同條件下進行熱再生；並進一步利用硫酸、硝酸、鹽酸、氫氧化鈉等試劑配合不同活化參數(濃度、時間、溫度)進行化學活化。研究結果顯示熱活化對提升廢矽藻土物性效果並不明顯，而化學活化之最佳條件為活化濃度2.25 M NaOH、活化時間2 hr、活化溫度為沸騰狀態、樣品重/活化液比為5/100的條件下，比表面積由0.3 m2/g提升至約100 m2/g，孔洞體積也由0.0039 cm3/g提升至0.258 cm3/g。
Diatomaceous earth, a clay mineral and characteristic of pore structure and negatively polar nature in the surface, is used extensively as filter and/or filter aid for the removal of all impurities in the industrial processes. The spent diatomaceous earth is thus generated and mostly disposed of landfill without further treatment for resource utilization.
The objective of this work is to study thermal regeneration by using horizontally rotary activation furnace under different parameters. Further, chemical activation has been carried out by using acid /alkaline agents such as sulfuric acid, acetic acid, hydrochloric acid and sodium hydroxide, and different activation parameter such as concentration, time and temperature. Under the experimental conditions investigated, the thermal regeneration process is not good for upgrading the physical properties of spent diatomaceous earth, The impregnation conditions at concentration of NaOH 2.25 M, impregnation temperature of boiling, holding time of 2 hr and sample/solution ratio of 5/100 seemed to have the most determining effects on the development of pores. The chemically activated clay have larger surface areas (109 vs 0.3 m2/g) and total pore volumes (0.26 vs 0.004 cm3/g) than those of the spent diatomaceous earth.
The physical and chemical characterization of the resulting products obtained in this study were further examined based on the analyses of surface area/pore volume, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and main elements. Results showed that these samples are characteristic of type IV from N2 isotherm, indicating mesoporous structure. Further, the optimal porous material thus obtained was used as mineral adsorbent for paraquat adsorption, showing that it has a good adsorption capacities for removal of this organic contaminant from the fittings of Langmuir and Freundlich isotherms.
|Appears in Collections:||[環境工程與科學系(所)] 博碩士論文|
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