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Reactive Extraction of Nicotinic Acid with Trialkylamine in n-Octanol 被引量:2
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作者 李德亮 于飞 常志显 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2012年第5期843-848,共6页
The distributions of nicotinic acid (NA) between water and trialkylamine (N235) dissolved in n-octanol was studied. The complexes of N235 and NA were investigated by Fourier transformation infrared spectrometry to ded... The distributions of nicotinic acid (NA) between water and trialkylamine (N235) dissolved in n-octanol was studied. The complexes of N235 and NA were investigated by Fourier transformation infrared spectrometry to deduce the reaction mechanism. It was found that N235/n-octanol was an efficient extractant for extracting nicotinic acid. The favorable operation conditions were equilibrium aqueous pH 4.2 to 5.5 and initial N235 concentration<0.42 mol·L-1 . The reaction processes included the reaction between neutral N235 and neutral NA and the reaction between protonated N235 and anionic NA. Based on the mass action law and some assumptions, an expression for distribution coefficient D was proposed. The apparent extraction equilibrium constants were calculated by fitting the experimental data and the results were satisfactory. 展开更多
关键词 nicotinic acid reactive extraction trlalkylamlne proton-transter
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北京市食品中天然铀、钍的测定及人体内照射有效剂量的估算 被引量:7
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作者 孔令海 徐海峰 +2 位作者 李宏 吕彩霞 高艳辉 《环境与职业医学》 CAS CSCD 北大核心 2016年第11期1089-1092,共4页
[目的]了解北京市市售主要食品的天然铀、钍含量及公众膳食中铀、钍放射性核素的摄入水平,估算所致人体内照射剂量,全面地掌握和评价公众膳食的安全性。[方法]本研究选用市场上销售的肉类、蔬菜、薯类、谷类、奶类5种食品样品,使用三正... [目的]了解北京市市售主要食品的天然铀、钍含量及公众膳食中铀、钍放射性核素的摄入水平,估算所致人体内照射剂量,全面地掌握和评价公众膳食的安全性。[方法]本研究选用市场上销售的肉类、蔬菜、薯类、谷类、奶类5种食品样品,使用三正辛胺萃取-分光光度法测定食品样品中铀、钍浓度,然后依据联合国原子辐射效应科学委员会(UNSCEAR)2008年报告书中的方法,估算人体受到内照射的有效剂量。[结果]5种食品样品中,铀含量浓度最高的为谷类,其值为1.86×10-6 g/kg;钍含量浓度最高的为肉类,其值为2.28×10-6 g/kg,测定结果均低于GB 14882—1994《食品中放射性物质限制浓度标准》的浓度限值。铀、钍放射性核素对人体内照射的年待积有效剂量成人为0.951μSv/a,其中铀的剂量贡献为0.318μSv/a,钍的剂量贡献为0.633μSv/a;儿童为0.666μSv/a,其中铀的剂量贡献为0.243μSv/a,钍的剂量贡献为0.423μSv/a。[结论]5种食品中铀、钍含量测定结果均低于GB 14882—1994中规定的浓度限值;成人的铀、钍放射性核素内照射剂量大于儿童,钍的剂量贡献大于铀。 展开更多
关键词 食品 三正辛胺萃取 内照射 有效剂量
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