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In this study, the potential of organic acids (formic acid, acetic acid) in a catalytical and mechanocatalytic conversion of lignocellulosic barley straw to valuable sugars is explored using sulfuric acid as a reference. Acid-catalyzed hydrolysis has been carried out with acid-impregnated samples as well as unmodified barley straw. In the mechanocatalytical approach, pretreatment consists of impregnation with the acid catalyst and mechanical treatment by ball milling following chemical hydrolysis. Straw samples and residues were analyzed by Fourier transform infrared spectrometry (FT-IR) whereas hydrolysate analysis was based on total reducing sugar (TRS) determination following the DNS method and capillary electrophoresis (CE) analysis. The results indicated that acetic acid and formic acid are rather mild acids yielding low TRS levels compared to the reference acid. Mechanocatalytical pretreatment slightly increased TRS yields, but not significantly. Strikingly, sulfuric acid showed an efficient conversion efficiency yielding almost 45% of TRS. Furthermore, this study provided evidence for the acetylation of straw components when acetic acid was used as catalyst. Alkali hydrolysis induced the de-esterification, but revealed no significant increase of TRS yields. 相似文献
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目的为减少大肠菌群检测中的实验误差,提高检验精确度,对大肠菌群MPN计数法不确定度进行评估。方法使用大肠杆菌标准菌株,分析大肠菌群检测结果的不确定度来源,对测定过程中引入的不确定度分量进行评定。采用合成的方法计算检验结果的不确定度。结果合成不确定度为0.06398,扩展不确定度为0.1446(以对数计)。大肠杆菌含量范围结果为1212~2358 MPN/m L。结论本研究发现重复性对不确定度影响最大,应在分析过程中注意控制。 相似文献
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