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1.
目的研究基于中红外光谱(mid infrared spectroscopy,MIRS)技术定性判别有机微量元素添加剂掺假的可行性。方法以甘氨酸铁螯合物和硫酸亚铁为研究对象,分析样品的中红外光谱,解析不同样品光谱的特异性;建立偏最小二乘判别(partial least squares discriminant analysis,PLS-DA)校正模型对掺假样品进行判别,并比较不同预处理方法、全光谱与特征波段对校正模型判别效果的影响。结果甘氨酸铁螯合物与硫酸亚铁光谱差异显著,主要分布在(3500~3000) cm~(-1)、(1600~1300) cm~(-1)、(1300~1000) cm~(-1)、(660~550) cm~(-1),通过采用平滑(smoothing,SM)、归一化(normalization,Norm)与一阶导数(first derivative,FD)相结合的方法对光谱进行预处理,结合1300 cm~(-1)~1000 cm~(-1)波段建立的PLS-DA校正模型判别效果最优,校正集的判别正确率为97.5%,验证集的判别正确率为100.0%,对外部样品的判别正确率达到92.7%。结论中红外光谱技术结合化学计量学方法能够对甘氨酸铁螯合物的掺假进行准确判别。 相似文献
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Weihua Shen Qing Ge Kaijie Gu Yingying Nie Linyu Jiao Zhiqing Zhu Yunjin Fang 《化学工程与技术》2020,43(12):2359-2364
The transesterification of dimethyl carbonate with phenol to methyl phenyl carbonate (MPC) was investigated on novel catalysts such as titanium diisopropoxide bis(ethyl acetoacetate) and titanium dibutoxide bis(ethyl acetoacetate) in a closed batch reactor at 185–206 °C under high pressure. The produced methanol could be removed efficiently by reactive distillation in order to overcome the equilibrium. The prepared catalysts have higher resistance to water than titanium alkoxides. Phenol conversion as high as 86.4 % with an MPC selectivity of 99.4 % was achieved under optimal reaction conditions within 9 h. Most of the catalytic activity was retained after repeated use for ten times. 相似文献
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Yuhan Jiang Jing Li Huan Zhao Runtian Zhao Yi Xu Xiaoling Lyu 《International Journal of Food Science & Technology》2021,56(1):166-177
Grape seed polypeptide (GSPP) was obtained by liquid fermentation with Bacillus subtilis TK15.015 from waste grape seed pomace. Its chelation ability with calcium ions was excellent. Simulation of in vitro gastrointestinal digestion showed that GSPP and calcium chelate (GSPP-Ca) slowly released calcium and decreased stomach stimulation. The solubility and transmission rate of GSPP-Ca after digestion in the gastrointestinal tract for 8 h maintained high levels of 74.4% and 46.4%, respectively, which far exceeded the levels achieved by other calcium supplements. Structural characterisation showed that calcium ions mainly react with binding sites present in peptides such as carboxyl oxygen, hydroxyl oxygen, amino nitrogen and amide bonds. GSPP-Ca may be a state in which a calcium-encapsulating complex formed, leaving calcium ions in a soluble state, suggesting its possible use as a high-quality calcium supplement. 相似文献
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以苯酚、乙醛酸和乙二胺等为原料,通过曼尼希反应一步得到乙二胺二邻羟苯基乙酸(o,o-EDDHA),通过FT-IR、1H NMR对其进行了表征。研究了反应温度、反应时间、配料比、原料浓度、相转移催化剂种类等对o,o-EDDHA收率和选择性的影响。研究结果表明EDDHA的优化合成条件为:反应温度55℃,反应时间为3 h,配料比为苯酚∶乙醛酸∶乙二胺∶氢氧化钠=2.6∶2∶1∶0.1(摩尔比),乙醛酸的浓度为20%,相转移催化剂为四丁基氢氧化铵,目标产物o,o-EDDHA的最高收率可达到69.7%,选择性达97%,与相关文献报道中的收率和选择性相比具有很大提高。 相似文献
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The displacement of sorbed metals during the treatment of soils and groundwater with modified Fenton's reagent was investigated using five common metal contaminants (cadmium, copper, lead, nickel, and zinc) and kaolinite as a model sorbent. Modified Fenton's conditions included three H(2)O(2) concentrations (0.9, 1.8, 2.7 M) and two catalysts: soluble iron (III) at pH 3 and iron (III)-NTA chelate at pH 6. Iron (III)-catalyzed Fenton's reactions released significant amounts of zinc, cadmium, and copper. Modified Fenton's reactions catalyzed by iron (III)-NTA released zinc, cadmium, copper, and lead, and resulted in greater amounts of metals release than the iron (III)-catalyzed reactions. Metals release may have been mediated by transient oxygen species, such as superoxide, generated by propagation reactions, which become dominant at the relatively high hydrogen peroxide concentrations used. Metals release from kaolinite was undetectable when sufficiently low hydrogen peroxide concentrations were maintained to minimize propagation reactions. These results indicate that using dilute concentrations of hydrogen peroxide for Fenton's ISCO may minimize potential metals mobility when treating contaminated soils and groundwater containing a mixture of organic and metal contaminants. 相似文献
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Girish M. Deshmukh Aparna Shete Deepali M. Pawar 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(3):432-436
BACKGROUND: Oxidative absorption of hydrogen sulfide into a solution of ferric chelates is studied in a stirred cell glass reactor. The experiments were performed to investigate the degradation of chelates sodium salt of nitrilotriacetic acid (NTA) (Merck), ethylenediaminetetraacetic acid diadisodium salt (EDTA) and diethylenetriaminepentaacetic acid (DTPA) at 313 K, pH 6, iron concentration 10 000 g L?1 and Fe:chelate molar ratio 1:2. RESULTS: Oxidative absorption of hydrogen sulfide into a solution of Fe‐NTA was found to be more successful, therefore, further experiments with 10%, 50% and 100% concentrations of hydrogen sulfide were performed. It was shown that this process is applicable for removal of low and high concentrations of hydrogen sulfide. The effect of antioxidants using sodium thiosulfate was also studied in order to minimize degradation of NTA. The kinetics were studied and it was observed that the reaction appeared to be first order in ferric chelate with rate constants for 100, 50 and 10% hydrogen sulfide concentration: 0.035, 0.013 and 0.019 h?1, respectively. CONCLUSIONS: Gas sweetening processes have commercial importance in natural gases, refinery of gases and biogas processing. Desulphurization and cleaning (i.e. removal of H2S and CO2) of petroleum gas and biogas is important to make the gas methane rich and to increase the calorific value of fuel. The same techniques of desulphurization and cleaning can be used for treating natural gas or petroleum gas. The desulphurization and cleaning processes can minimize the atmospheric emission of gases like SOx, NOx and CO. As the iron chelate based process is based on the principle of redox reaction of metal chelate with hydrogen sulfide, this method is very useful for desulphurization of petroleum gas and biogas. This work studied the effective use of Fe‐NTA solution for removal of high to low concentrations of H2S as found in biogas and industrial waste gases. © 2012 Society of Chemical Industry 相似文献
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