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修改文章，主要从语言逻辑和行文顺序上修改，最好修改的地方标注出来。需要全文的请留言。 2. Experimental 2.1 Materials and reagents Analytic reagents H2SO4, H2O2 and NH3•H2O (Tianjin Kaitong Chemical Co.) were used without further purification. Ultrafine iron oxide particles (Hunan three-ring Pigment Co.), uniformity in spherical shape and approximately 0.3 µm in diameter, were used as seed crystal for the hydrothermal reaction. The pyrite cinders used as a raw material for iron source in the experiment were obtained from Guangdong Pyrite Mine Corporation in Guangdong province of China. Its chemical composition was examined by X-ray fluorescence spectroscopy (XRF), mainly consisted of Fe (58.15 wt. %), Si (5.545 wt. %), S (1.951 wt. %), Al (1.62 wt. %), Ca (1.04 wt. %), Mg (0.368 wt. %) and so on. The mixture of ferric and ferrous sulfate was prepared from pyrite cinders through sulfuric acid leaching process following the protocol described by Zheng et al. [30]. Initially, 6.5 L 50 wt. % sulfuric acid solution was added to a three-necked flask (10 L in volume). Then, 3 kg of pyrite cinders was gradually added into the sulfuric acid solution under vigorous stirring. The leaching temperature was controlled at 115 °C by an electric heating-jacket, and kept for 4 hours. After filtration, the leached solution was diluted to 9.0 L with deionized water, which was mainly composed of a mixture of ferric sulfate and ferrous sulfate (Table 1), containing trace impurity elements such as Al, Mg, Ca and so on. The as-prepared acidic leached solution was used as the starting material to prepare hematite. 2.2 Synthesis of hexagonal hematite (α-Fe2O3) platelets The typical procedure used to prepare hexagonal hematite platelets from an acidic leached solution of pyrite cinders is summarized in Fig. 1. Under vigorous stirring, hydrogen peroxide solution was added dropwise into the filtrate solution, and a part of ferrous sulfates was oxided in order to regulate ferrous concentration to a desired value (n Fe(II)/n Fe(III) =0.08). Liu et al [31] proposed a small amount of Fe (II) could catalyze the formation of hematite. Then, ammonia solution (25 wt. %) was dropwise added into 200 mL above iron solution (total iron concentration 2.5 M) until the pH of the suspension reached 7. Subsequently, 2 g of ultrafine hematite particles were added into the suspension with a total volume of 400 mL. The final suspension was transferred to a 500 mL autoclave with a mechanical stirrer, sealed and maintained at 140 °C, 170 °C, 200 °C and 230 °C for 0.5 h, respectively. After the heating treatment, the reactor was allowed to cool down to room temperature by an internal cooling coil of it. The resulting products were filtered and rinsed with deionized water, and finally dried at 105 °C for 12 h. 2.3 characterization Chemical analysis of the liquids was performed to examine the ferrous and ferric ion concentrations by a titration method according to GB 1863-2008 (China Industrial Standard). The results were the mean values of the two experiments using the same sample. X-ray diffraction (Rigaku, D/max-rA) with Cu-Kα (λ=1.540562Å  radiation was used to check the formation and to identify the compositions of the obtained particles. 2θ scanning scope was 10.0° to 70.0° with a step of 0.01°/s. TEM patterns were recorded on a Hitachi Model H-800 transmission electron microscope at an accelerating voltage of 200 kV. The samples were dispersed in absolute ethanol in an ultrasonic bath. Then a drop of suspension was put onto a copper grid and dried naturally. Selected area electron diffraction (SAED) was further performed to identify the crystallinity. The mean particle size and surface morphology of the typical particles were observed with a scanning electron microscope (SEM, JSM-6360LV, JEOL, Ltd., Tokyo, Japan). |
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小修改
allen123456(金币+15): 2010-04-12 20:37
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2. Experimental 2.1 Materials and reagents Analytic reagents H2SO4, H2O2 and NH3•H2O 格式应该规范(Tianjin Kaitong Chemical Co.) were used without further purification. Ultrafine iron oxide particles (Hunan three-ring Pigment Co.), uniformity in spherical shape and approximately 0.3 &micr o既然用分号，就应该是一句话，但是没有系表动;m in diameter, were used as seed crystal for the hydrothermal reaction. The pyrite cinders used as a raw material for iron source in the experiment were （应该是was 主谓一致性）obtained from Guangdong Pyrite Mine Corporation in Guangdong province of China. Its chemical composition was examined by X-ray fluorescence spectroscopy (XRF), mainly consisted of Fe (58.15 wt. %), Si (5.545 wt. %), S (1.951 wt. %), Al (1.62 wt. %), Ca (1.04 wt. %), Mg (0.368 wt. %) and so on（好像有点口语etc是不是好点）. The mixture of ferric and ferrous sulfate was prepared from pyrite cinders through sulfuric acid leaching process following the protocol described by Zheng et al. [30]. Initially, 6.5 L 50 wt. % sulfuric acid solution was added to a three-necked flask (10 L in volume). Then, 3 kg of pyrite cinders was gradually added into the sulfuric acid solution under vigorous stirring. The leaching temperature was controlled at 115 °C by an electric heating-jacket, and kept for 4 hours. After filtration, the leached solution was diluted to 9.0 L with deionized water, which was mainly composed of a mixture of ferric sulfate and ferrous sulfate (Table 1), containing trace impurity elements such as Al, Mg, Ca and so on. The as-prepared acidic leached solution was used as the starting material to prepare hematite. 2.2 Synthesis of hexagonal hematite (α-Fe2O3) platelets The typical procedure used to prepare hexagonal hematite platelets from an acidic leached solution of pyrite cinders is （时态保持一致性 过去时啊）summarized in Fig. 1. Under vigorous stirring, hydrogen peroxide solution was added dropwise into the filtrate solution, and a part of ferrous sulfates was oxided in order to regulate ferrous concentration to a desired value (n Fe(II)/n Fe(III) =0.08). Liu et al [31] proposed a small amount of Fe (II) could catalyze the formation of hematite. Then, ammonia solution (25 wt. %) was dropwise added into 200 mL above iron solution (total iron concentration 2.5 M) until the pH of the suspension reached 7. Subsequently, 2 g of ultrafine hematite particles were added into the suspension with a total volume of 400 mL. The final suspension was transferred to a 500 mL autoclave with a mechanical stirrer, sealed and maintained at 140 °C, 170 °C, 200 °C and 230 °C for 0.5 h, respectively. After the heating treatment, the reactor was allowed to cool down to room temperature by an internal cooling coil of it. The resulting products were filtered and rinsed with deionized water, and finally dried at 105 °C for 12 h. 2.3 characterization Chemical analysis of the liquids was performed to examine the ferrous and ferric ion concentrations by a titration method according to GB 1863-2008 (China Industrial Standard). The results were the mean values of the two experiments using the same sample. X-ray diffraction (Rigaku, D/max-rA) with Cu-Kα (λ=1.540562Å radiation was used to check the formation and to identify the compositions of the obtained particles. 2θ scanning scope was 10.0° to 70.0° with a step of 0.01°/s. TEM patterns were recorded on a Hitachi Model H-800 transmission electron microscope at an accelerating voltage of 200 kV. The samples were dispersed in absolute ethanol in an ultrasonic bath. Then a drop of suspension was put onto a copper grid and dried naturally. Selected area electron diffraction (SAED) was further performed to identify the crystallinity. The mean particle size and surface morphology of the typical particles were observed with a scanning electron microscope (SEM, JSM-6360LV, JEOL, Ltd., Tokyo, Japan). 不好意思，只看到了一些小错误，好象不是一个方向的，有的看不懂 |
2楼2010-04-12 17:18:20
3楼2010-04-12 20:35:26
4楼2010-04-12 20:37:35
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