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排序方式: 共有923条查询结果,搜索用时 93 毫秒
921.
近红外光谱法同时测定卷烟纸中的钾和钠 总被引:2,自引:0,他引:2
为适应快速分析卷烟纸中K和Na含量的需要,应用傅立叶变换近红外(FT-NIR)光谱法和常规化学分析方法分别测定了101个卷烟纸样品的光谱数据和K及Na含量.以光谱数据和检测数据为基础,利用偏最小二乘法建立了预测卷烟纸中K和Na含量的数学模型,并进行了样品扫描条件和模型的优化.结果表明:每个纸样取14张扫描比较适宜;K和Na建模的适宜谱区范围均为4 000-7 700 cm<'-1>;一阶导数+Norris导数滤波法进行光谱预处理;K和Na优化模型的R分别为0.990 6和0.986 5,RMSECV为0.065 7和0.035 9,其预测值与化学测定值的平均相对偏差各为9.63%和9.03%. 相似文献
922.
Ren A. Rozendal Emilie Leone Jürg Keller Korneel Rabaey 《Electrochemistry communications》2009,11(9):1752-1755
Hydrogen peroxide (H2O2) is an important industrial chemical, but its current production methods are highly energy-intensive. This study presents a novel process for the production of H2O2 based on the bioelectrochemical oxidation of wastewater organics at an anode coupled to the cathodic reduction of oxygen to H2O2. At an applied voltage of 0.5 V, this system was capable of producing 1.9 ± 0.2 kg H2O2/m3/day from acetate at an overall efficiency of 83.1 ± 4.8%. As most of the required energy was derived from the acetate, the system had a low energy requirement of 0.93 kWh/kg H2O2. 相似文献
923.
Alexander Kaszonyi Lívia Izsk Milan Krlik Michal Jablonsky 《Molecules (Basel, Switzerland)》2022,27(9)
Samples of papers artificially (2 to 60 days) and naturally (10, 45, and 56 years) aged were studied by the Py-GC/MS method to identify decomposition products. Possible reaction scenarios for cellulose degradation were developed. One of the degradation products is acetic acid, which can (auto)catalyze the cleavage of cellulose β(1→4)-glycosidic bonds of cellulose polymer chains. However, during 20 s of Py-GC/MS analysis, temperatures of up to 300 °C did not significantly increase or modify the formation of decomposition products of paper components. At 300 °C, the amount of several cellulose decomposition products increased regularly depending on the number of days of artificial aging and natural aging, demonstrated mainly by the generation of 2-furancarboxaldehyde, 5-hydroxymethylfurfural, and levoglucosan and its consecutive dehydration products. No correlation between the amount of lignin decomposition products and the time of aging was found when the pyrolysis was performed at 300 °C and 500 °C. Compounds present in the products of decomposition at 500 °C bear the imprint of the chemical composition of the sampled paper. Pyrograms taken at 300 °C using the Py-GC/MS method can give additional information on the changes in the chemical structure of paper during natural or artificial aging, mainly about the cleavage of β(1→4)-glycosidic bonds during aging. 相似文献