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萃取精馏是分离沸点相近或具有恒沸组成混合物的一种重要方法。选择最优的萃取剂是提高生产能力和降低能耗的根本途径。萃取剂选择的计算机辅助分子设计(CAMD)是基于性质估算的方法即通过CAMD来生成一组具有期望性质的分子,然后再对候选分子进行筛选。目前,CAMD法的研究主要可分为生成一验证、数学优化和组合优化。生成一验证法通常使用启发式的策略,是基于知识的,无法克服基团的组合爆炸问题,也不能保证结果的最优性;数学优化方法,包括混合整数非线性规划(MINLP)和混合整数线性规划(MILP),可用于表达非线性或线性的结构.性质关系,但准确表达结构-性质关系还有困难;组合优化法是使用遗传算法或模拟退火算法、禁忌搜索等的方法,理论上可克服以上问题。本文评述了以上三种方法在萃取精馏溶剂选择领域中的用途、原理及其工业化所面临的主要问题。 相似文献
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过氧化氢(H2O2)是强氧化剂,在治理污水中有十分重要的意义,对水中脉冲放电中电压对它的影响进行了研究。结果表明,电压越高,时间越长,H2O2的生成速率减小越快;不同气体成分和流量对H2O2生成也有影响。 相似文献
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H2O2能够氧化偶氮染料刚果红使之褪色,而模拟酶—血红蛋白对其具有催化作用。据此建立了一种以刚果红为指示剂的H2O2-刚果红-血红蛋白酶催化反应体系测定痕量H2O2的新方法。确定了反应的最佳条件,体系的酸度为pH10.7的NH3-NH4Cl缓冲溶液,最大吸收波长为497 nm。该法的线性范围为8.0×10^-8-8.0×10^-5mol/L,检出限为1.97×10^-9mol/L,表观摩尔吸光系数为4.6×10^4L.mol-1.cm^-1。该方法可用于雨水及消毒水中H2O2的测定。 相似文献
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色谱法筛选C_9芳烃萃取精馏溶剂 总被引:4,自引:0,他引:4
将萃取精馏溶剂作为气相色谱固定液,利用气-液色谱法对C9芳烃所用溶剂进行了选择。共测试环丁砜、邻苯二甲酸二甲酯等7种溶剂。其中邻苯二甲酸二甲酯对C9芳烃异构体的分离效果较好。方法省时省力,消耗少,结果可靠。 相似文献
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A Fuzzy Divisive Hierarchical Clustering Algorithm for the Optimal Choice of Sets of Solvent Systems
《Analytical letters》2012,45(5):1031-1054
Abstract This paper proposes a Fuzzy Divisive Hierarchical Clustering Algorithm (FDHC) for the optimal choice of sets of solvents systems in thin layer chromatography. This new approach described here is capable of finding the best system and the optimal combination of two or more TLC systems according to, for instance, the quality partition coefficient (QP). In this order an IBM-PC computer has been used to run the corresponding program written in Pascal. 相似文献
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WeiHuang CuihongZhang LihuaYin KechangXie 《天然气化学杂志》2004,13(2):113-115
The possibility of synthesizing acetic acid from CH4 and CO2 in the presence of O2 over a V2O5-PdCl2/Al2O3 catalyst has been explored. The result shows that it is feasible in catalyzing a direct conversion of CH4, CO2 and O2 to acetic acid. It is concluded that both CO2 and O2 are involved in the formation of acetic acid. 相似文献
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A simple and sensitive method is presented for the determination of two well‐known xenoestrogens alkylphenols (4‐tert.‐octylphenol (4‐t‐OP) and 4‐nonylphenol isomers (4‐NPs)) in oysters and snails. The method involves extraction of the sample by a modified Nielson‐Kryger steam distillation extraction, and the alkylphenols were then identified and quantitated by gas chromatography‐mass spectrometry (GC‐MS) in selected ion monitoring (SIM) mode. The quantitation limit of this method was less than 20 ng/g in 0.5 g (dry weight) of the samples. The perfect applicability of the steam distillation extraction method for 4‐t‐OP and 4‐NPs was determined after testing it with spiked and real samples. Recovery of 4‐t‐OP and 4‐NPs in spiked tissue samples was above 88% while relative standard deviation (RSD) ranged from 7 to 14%. 4‐tert.‐octylphenol and 4‐nonylphenol isomers are ubiquitous in oysters and snails with the concentrations of 4‐t‐OP and 4‐NPs ranging from 70 to 820 ng/g and from 210 to 2750 ng/g (dry weight), respectively. 相似文献
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Zincisanecessarylifeelementinhumanbody.L-α-aminoacidisthebasicunitofproteinrelatedwithlife.L-α-Thr(Threonine),L-α-Phe(Phenylalanine),L-α-Val(Valine)andL-α-Met(Methionine)arein-dispensabletolifewhichhavetobeabsorbedfromfoodbecausetheycannotbesynthesizedinhumanbody.Thecomplexesofzincsaltswithα-aminoacidasad-ditivehaveawideapplicationinmedicine,foodstuffandcosmetics犤1~3犦.Thesynthesismethodsofthecom-plexesofzincsaltswithα-aminoacidhavebeenre-viewed犤… 相似文献
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Cecil F. Wells 《Journal of solution chemistry》2000,29(3):271-287
The photo-absorbing, basic sensor, 4-nitroaniline, has been used to determine theequilibrium constant for solvent reorganization around the proton in mixtures ofvarying composition of water with acetic acid. In all the mixtures used, theself-ionization of the acetic acid was suppressed. In contrast to mixtures of waterwith the related ethanol or acetone, this equilibrium is shifted more toward thewater-solvated species as the mole fraction x
2 of the cosolvent increases. TheGibbs energy of transfer of protons from water into the mixture G
o
t
(H+) can bederived with the aid of this equilibrium constant for the solvent reorganization.Using G
o
t
(H+), G
o
t
(i) for i denoting anions and other cations can be evaluated.In comparison the G
o
t
(i) for cations have lower negative values than when eitherethanol or acetone is added to water. Correspondingly, for halide anions, thepositive G
o
t
(i) with added acetic acid are rather less than is found with eitherethanol or acetone added. The influence on the ion-solvent interaction of bothelectron withdrawing hydroxy and carbonyl groups in acetic acid may beresponsible for this. Although G
o
t
(i) for C10–
4 and Re0–
4 are also positive, both picrateions and OH– give negative values with acetic acid added to water. With picrateions, the hydrophobic effect of the carbon ring produces stabilization in themixture relative to water. With OH–, complete conversion to acetate anionsoccurs. As is found with other cosolvents, the contribution of the charge onacetate anion to G
o
t
(CH3COO–) is found to increase as x
2 rises. The aciddissociation constant K
a
for acetic acid is found to decrease slowly as x
2 rises to0.5, followed by a rapid decrease for x
2 greater than 0.7 where dimerization ofacetic acid occurs. 相似文献
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In this technoeconomic evaluation of the manufacture of acetic acid by fermentation, the use of the bacterium:Acetobacter suboxydans from the old vinegar process was compared with expected performance of the newerClostridium thermoaceticum bacterium. Both systems were projected to operate as immobilized cells in a continuous, fluidized bed bioreactor, using solvent
extraction to recover the product.
Acetobacter metabolizes ethanol aerobically to produce acid at 100 g/L in a low pH medium. This ensures that the product is in the form
of a concentrated extractable free acid, rather than as an unextractable salt. Unfortunately, yields from glucose by way of
the ethanol fermentation are poor, but near the biological limits of the organisms involved. 相似文献
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绿豆提取物排铅效果的实验研究 总被引:9,自引:0,他引:9
林宣贤 《广东微量元素科学》2005,12(5):66-68
观察了绿豆提取物对铅中毒动物的排铅作用,用SD雄性大鼠建立铅中毒模型,按体质量随机分组对照。结果表明,绿豆提取物可以增加铅中毒大鼠的铅排出量,降低骨铅和肝铅。提示绿豆提取物具有促进铅的排出和减少体内铅蓄积的作用。 相似文献
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《Analytical letters》2012,45(4):293-298
Abstract A carrier distillation method is described for determination of boron in calcium fluoride. The sample is mixed with 5 % copperoxyfluoride containing 200 ppm of gallium. 50 mg of this mixture is loaded in pre-arced U. C. C. 1990 electrode and excited using 15 amp. d. c. arc. The resulting spectra are recorded in the region 2200 to 2850 A employing Hilger large quartz spectrograph. The detection limit for boron is 0.1 ppm and the precision of the method is ± 12%. 相似文献