Selective removal of caffeine from tea extracts using macroporous crosslinked polyvinyl alcohol adsorbents

The hydrolysis reaction of ester groups in vinyl acetate (VAc) was used to introduce hydroxyl groups into the matrix of a macroporous adsorbent, which was itself prepared by free radical suspension copolymerization of triallyl isocyanurate (TAIC) and VAc. Therefore, the copolymerization incompatibility between the hydrophilic and the hydrophobic monomer was overcome successfully and the hydrophobic matrix of the polymeric adsorbent containing a polyvinyl alcohol (PVA) segment was obtained. Introduction of the PVA segment decreased the hydrophobic adsorption affinity of the adsorbent while producing the hydrogen-bonding interaction. When isolating the two active components, polyphenols (TPh) and caffeine (CAF), from green tea extracts, this polymeric adsorbent, namely poly(TAIC-co-VA), exhibited good adsorption selectivity towards TPh over CAF. The adsorption mechanism leading to this selectivity involved a hydrophobic interaction mechanism for CAF and multiple weak hydrophobic and hydrogen-bonding interactions for TPh. The adsorption thermodynamics for TPh on poly(TAIC-co-VA) were studied. The effects of adsorbent structure and gradient desorption conditions on isolation were investigated. The result showed that adsorbent, with 20% TAIC content, was able to efficiently remove CAF from different tea extracts with different ratios of TPh and CAF. Finally, almost no CAF was detected in the TPh fraction and the recovery of TPh was greater than 95%.     

微多相聚氨酯大孔树脂吸附胆红素的研究

本文报道了一种具有新型骨架结构的微多相聚氨酯大孔树脂对胆红素的吸附，结果表明，该吸附剂对水溶液中的胆红素吸附率为77.5％，对与人血清白蛋白结合胆红素的吸附率为56．6％，并且吸附的选择性高，受人血清白蛋白和氨基酸的影响比较小。     

葡萄色素的提取及稳定性研究

用树脂吸附、膜分离方法处理葡萄酒糟色素提取液 并将色素提取液对热、光和长时间放置的稳定性进行了评价     

HAuCl_4在笼形聚偕胺肟树脂上的吸附及结晶过程

制备了一系列以无机酸、有机酸和酚类化合物处理的宪形聚偕胺后树脂（HX/ACAO、RCO2H/ACAO、Ph/ACAO），测定了它们对HAuCl4的吸附容量，发现吸附能力与质子酸的pka值有关，酸阴离子的结构也有一定的影响，pka值越高，酸阴离子的空间位阻越小，吸附HAuCl4的能力越强。从扫描电镜观察到HAuCl4被还原为单质金后，在ACAO表面上形成晶核，并迅速增长成晶粒、晶须和晶块。     

Potential of metal–fullerene hybrids as strong nanocarriers for cytosine and guanine nucleobases: A detailed DFT study

In this article, the adsorption of cytosine and guanine molecules on the surface of Cr-doped C20 fullerene (C19Cr) and Ni-doped C20 fullerene (C19Ni) are studied using first-principles density functional theory (DFT) calculations. In order to thoroughly comprehend the influences of the molecules on the metal-fullerene complexes, the geometric parameters, the binding energies, transferred charges, the magnitude of dipole moments, thermochemical parameters, frontier molecular orbitals, and the global indices of activities are calculated. The results highlighted that the interactions of both cytosine and guanine molecules with metal-fullerene complexes are highly exothermic, suggesting that these molecules might be chemisorbed on their adsorbents. The C19Cr exhibits a better adsorption behavior toward the molecules compared to C19Ni, and cytosine has the higher binding energies with metal-fullerene complexes in comparison with guanine. Further analyses showed that the C19Cr experiences significant changes in its electronic properties upon adsorption of the cytosine molecule. However, the small variations in the electronic properties of C19Ni after complexation with guanine indicate that this complex is not sensitive to the guanine. Furthermore, the results of frontier molecular orbital reveal the strong (moderate) interactions between the C19Cr with the cytosine (guanine) molecule and moderate (weak) interactions between the C19Ni with the cytosine (guanine) molecule. Therefore, the C19Cr and C19Ni have moderate sensitivities to cytosine and guanine molecules. More excitingly, our findings divulge promising potential of the Cr-fullerene complex as a biochemical adsorbent for cytosine.     

STUDY ON THE TREATMENT OF3-PHENOXY-BENZALDEHYDE INDUSTRIAL WASTEWATER WITH POLYMERIC ADSORBENT

1.INTRODUCTIONResinadsorption(RA)iswidelyusedinthetreatmentofwastewatercolltainingorganiccontaminantsll--5].Theprocessincludesadsorptionanddesorption.WhenaflowofwastCwaterisdeliveredtoanadsorptionresinbed(oftenfixedbed,foritsconveniencetooperate),thedrainwateriscleanedandtheimpuritiesareabsorbed.Theusedresinisdesorpedorregeneratedbyusingaregenerant.Theorganiccompoundsabsorbedintheresinarethenextraaedbytheregenerant16'71.Insomecases,theorganiccompoundintheregenerantsolutionisvaluableandw…     

Characterization of pore structure of a strong anion-exchange membrane adsorbent under different buffer and salt concentration conditions

The quantitative characterization of pore structure of Sartobind Q, a strongly basic membrane anion exchanger that is formed by cross-linked cellulose support and a hydrogel layer on its pore surface, was made combining the results obtained by several experimental techniques: liquid impregnation, batch size-exclusion, inverse size-exclusion chromatography, and permeability. Mercury intrusion and nitrogen sorption porosimetry were carried out for a dry cellulose support membrane in order to get additional information for building a model of the bimodal pore structure. The model incorporated the distribution of the total pore volume between transport and gel-layer pores and the partitioning of solutes of different molecular weights was expressed through the cylindrical pore model for the transport pores and random plane model for the gel layer. The effect of composition of liquid phase on the pore structure was investigated in redistilled water, phosphate and Tris–HCl buffers containing up to 1 M NaCl. Evident differences in the bimodal pore structure were observed here when both the specific volume and size of the hydrogel layer pores significantly decreased with the ionic strength of liquid phase.     

A new catalytic mode of the modularly designed organocatalysts (MDOs): enantioselective synthesis of dihydropyrano[2,3-c]pyrazoles

The enantioselective tandem Michael addition-cyclization reaction between 3-methyl-2-pyrazolin-5-one and benzylidenemalononitriles was studied with modularly designed organocatalysts (MDOs) to yield 6-amino-5-cyanodihydropyrano[2,3-c]pyrazoles in high yields and moderate to good enantioselectivities. Most importantly, a new catalytic mode of the MDOs was established. Instead of being used as a nucleophile to form an enamine intermediate, the reaction center modules (amino acids) of the MDOs are now used as a Lewis base in this base-catalyzed reaction. Since there are more reactions catalyzed by Lewis bases than by the enamine mechanism, this finding greatly expands the scope of the MDOs in organic reactions. On the other hand, because the stereocontrolling modules (cinchona alkaloid derivatives) themselves may be used as Lewis base catalysts, this new method may also be viewed as an expeditious way for the modification of the reaction center of the cinchona alkaloid catalysts.     

基于QuEChERS-HPLC法检测油炸食品中丙烯酰胺的含量

建立了基于QuEChERS(quick,easy,cheap,effective,rugged and safe)-HPLC测定油炸食品中丙烯酰胺含量的方法。 该方法的优势在于：改进的QuEChERS前处理方法中没有引入有机溶剂而直接采用纯水消除样品基底的影响。 研究中,使用纯水超声提取丙烯酰胺,丙基乙二胺(PSA)吸附剂分散净化提取液,乙腈和水(体积比1∶99)作为流动相,水系C18色谱柱分离,208 nm紫外波长条件下检测丙烯酰胺的含量。 结果表明,丙烯酰胺在0.020~0.800 μg/g浓度范围内与出峰面积呈线性关系,相关系数r=0.9994;检测限为0.005 μg/g;加标回收率为83.96%~89.43%,相对标准偏差(RSD)为2.13%~5.87%。 该方法具有操作简单、快速、可靠和灵敏度高等特点,成功应用于方便面等油炸食品中丙烯酰胺含量的测定。     

提拉法生长高质量氟化镁单晶

设计了适合提拉法生长氟化镁单晶体的温场,采用提拉法成功生长出了直径100 mm的高质量氟化镁单晶.晶体内无气泡等宏观缺陷、无开裂;通过精密退火处理后,晶体透过率达到95;,平均应力双折射小于0.5 nm/cm.上述结果表明采用提拉法可以生长高质量的氟化镁单晶.