氨基修饰超高交联树脂对单宁酸的吸附行为及机理研究

选用单宁酸作为天然有机酸中典型中分子、高水溶性有机酸,系统研究了氨基修饰超高交联树脂对单宁酸的吸附行为和机理.吸附等温线表明氨基修饰超高交联树脂WJN-08对单宁酸有较高的吸附容量,其静态饱和吸附量比传统商业吸附剂高15%以上;吸附表面分析表明离子键、π-π共轭作用和阳离子-π键是重要吸附作用力;吸附热力学试验表明树脂WJN-08吸附单宁酸是化学吸附主导,吸附焓变在20~22 kJ mol-1;吸附动力学试验表明树脂WJN-08吸附单宁酸速率同时受控于颗粒内扩散和膜扩散过程.动态小柱吸附-脱附实验表明树脂WJN-08对单宁酸有较好的吸附-脱附性能,饱和吸附量和穿透吸附量分别为24.43 mg g-1和19.56 mg g-1,脱附率为98.6%。     

复合功能树脂对水体中天然有机酸的吸附

合成了胺基修饰复合功能树脂WJN-07, 研究了富里酸、单宁酸和没食子酸在树脂上的吸附行为. 与去除DOM的商品树脂XAD-7相比, 树脂WJN-07对3种天然有机酸有较高的吸附容量, 这是由于新型树脂表面具有修饰的化学官能团和丰富的微孔结构所致. 选择单宁酸作为吸附质进行吸附热力学研究, 结果表明, 树脂WJN-07对单宁酸的吸附为吸热过程, 以化学吸附为主导. 溶液中重金属离子Pb²⁺作为影响树脂吸附性能的重要因素在实验中得到证实, 其作用机理也得到合理解释.     

胺基修饰的高度交联聚苯乙烯树脂对间苯二酚吸附行为研究

研究了AH系列胺基修饰的超高交联树脂对水溶液中间苯二酚的静态吸附行为特征,结果表明,它们对间苯二酚的吸附容量明显高于母体交联树脂NDA-100和大孔弱碱性阴离子交换树脂D301.AH系列树脂与吸附质分子之间不仅有范德华作用力,还存在着氢键等作用力.该类树脂对间苯二酚的吸附为自发的放热过程,属于以物理作用为主兼有弱化学作用的吸附过程.吸附速率符合准一级动力学方程,表观吸附速率常数随树脂胺基含量的升高而降低.     

酚羟基修饰的超高交联聚苯乙烯树脂对苯酚吸附及脱附性能的研究

对超高交联聚苯乙烯树脂进行酚羟基修饰得到修饰后的超高交联聚苯乙烯树脂(JN-2),将该树脂与大孔吸附树脂(Amberlite XAD-4)和超高交联树脂(NDA-150)在水溶液中对苯酚进行吸附-脱附性能比较,经过酚羟基修饰的超高交联聚苯乙烯树脂(JN-2)对苯酚的吸附性能有所提高,同时脱附性能明显改善,该树脂可望在含酚废水治理中得到广泛应用.     

超高交联树脂对水中双酚A的吸附行为研究

双酚A (BPA)作为一种内分泌干扰物可严重损害人类身体健康。本研究通过对苯乙烯系大孔树脂进行傅-克烷基化反应或三甲胺修饰,制得超高交联树脂HCR与胺基修饰超高交联树脂HCR-N。氮气吸附-脱附测试表明,HCR的比表面积为1262.51m²/g,远高于HCR-N。等温吸附结果显示,303K时HCR对BPA的最大吸附量为665.61mg/g,是HCR-N的3倍。与Lewis酸碱作用相比,BPA与树脂表面的π-π作用对吸附起到主导作用。此外,还考察了温度、pH值、吸附时间以及干扰离子对BPA吸附性能的影响。再生实验证实,乙醇对HCR具有更好的脱附效果,经过5次吸附-解吸,对BPA的吸附率仍高于80%,脱附率均超过90%,可实现对废水中BPA的资源化利用。     

不同基团修饰的吸附树脂对芳香两性化合物的吸附等温线研究

研究了带有不同功能基团的超高交联吸附树脂NG-10和NJ-99对水溶液中芳香两性化合物氨基苯甲酸的静态吸附性能,并与不带功能基团的吸附树脂CHA-111和XAD-4进行了比较.研究结果表明,树脂NJ-99对水溶液中氨基苯甲酸的吸附能力高于其他树脂.邻氨基苯甲酸在4种树脂上的吸附量均大于对氨基苯甲酸,主要原因是其溶解度小.吸附等温线采用经验的Freundlich方程和理论的Langmuir吸附方程来拟合,在实验所研究的浓度范围内,方程的拟合相关性均很好.     

新型胺基修饰的超高交联聚合吸附剂吸附水中酚类化合物的研究

合成了新的胺基修饰的超高交联AH系列吸附树脂．以弱碱树脂D301和超高交联吸附树脂ND100为参照，测定了AH系列吸附树脂吸附水中苯酚、对氯苯酚、对甲苯酚、对硝基苯酚的吸附性能。结果表明：修饰的超高交联吸附树脂对苯酚．对甲苯酚、对氟苯酚的吸附量比ND100和D301更大，而D301树脂对对硝基苯酚有最大的吸附量．提出了AH系列树脂对4种酚类化合物吸附行为的作用机理．     

酸性吸附树脂对2,6-二氯苯酚的吸附热力学和动力学研究

本文以二硫代二苯甲酸、均苯四甲酸酐和没食子酸为修饰剂,通过后交联反应和化学修饰反应制备了3种酸性功能基修饰的超高交联树脂。通过等温吸附实验和吸附动力学实验,探讨了3种酸性吸附树脂对2,6-二氯苯酚(2,6-DCP)的吸附性能和吸附机制。结果表明,3种酸性吸附树脂对2,6-DCP均具有良好的吸附性能,吸附量随着2,6-DCP初始浓度的增大而增加,随着温度的升高而减小。Langmuir和Freundlich等温吸附方程均能够较好地拟合吸附等温线,3种酸性树脂对2,6-DCP的吸附机理较复杂。吸附热力学结果表明,吸附过程主要为放热、自发的物理吸附过程。3种酸性树脂对2,6-DCP的吸附动力学过程符合准一级动力学方程,颗粒内扩散是该吸附过程的主要控制步骤。3种酸性吸附树脂对2,6-DCP的吸附速率常数大小顺序为kGAMRkDSTAMRkPMDAMR。     

苯酚和苯胺在超高交联吸附树脂上的共吸附行为

研究了水溶液中苯酚和苯胺在超高交联吸附树脂NDA103、NDA101、NDA100上的竞争吸附和协同吸附行为.实验结果表明,单组分苯酚或苯胺水溶液和双组分共存水溶液中吸附质分子在超高交联吸附树脂上的吸附等温线均符合Langmuir模型.当双组分摩尔比为1∶1时,在较低平衡浓度范围内苯酚和苯胺在树脂上呈现竞争吸附行为,其主导机制是两种吸附质分子对树脂内外表面上π-π作用吸附位点的直接竞争;而在较高平衡浓度范围内呈现协同吸附行为,其主导机制是两种吸附质分子之间的氢键作用.吸附温度由293K升至313K时,苯酚和苯胺在NDA103上的协同吸附作用加强,而在NDA101和NDA100上的协同吸附作用变化不明显.     

2,4-二硝基-6-溴苯胺生产废水中有机物的吸附回收工艺研究

通过Friedel-Crafts后交联反应制备了超高交联吸附树脂(YSS150)及二甲胺修饰的超高交联吸附树脂(YSS99),以Amberlite XAD-4树脂做参照,通过等温吸附-脱附、动态吸附-脱附及树脂稳定性实验,在筛选的基础上,研究了YSS150树脂对2,4-二硝基苯胺(2,4-dinitroaniline,DA)及2,4-二硝基-6-溴苯胺(2,4-dinitro-6-bromoaniline,DBA)的吸附效果及对2,4-二硝基苯胺及2,4-二硝基-6-溴苯胺的吸附回收工艺的可靠性.结果表明:YSS150树脂对水中2,4-二硝基苯胺及2,4-二硝基-6-溴苯胺具有较高的吸附容量,吸附等温线符合Freundlich方程,甲醇或8%盐酸具有较好的脱附效果.     

Adsorption and radical stabilization of humic-Acid analogues and Pb2+ on restricted phyllomorphous clay

Humic acids have stable radicals that are indigenous to their structure. Hydroxybenzoic acid derivatives such as gallic acid (GA) and protocatechuic acid are appropriate models for the radical properties of humic acids. Here we show that the adsorption or intercalation of gallic acid in Laponite clay results in a significant thermodynamic stabilization of gallic acid radicals. Moreover, the formed organoclay shows enhanced stability against acid dissolution. The structural details of the association of gallic acid with Laponite depend on the GA/Laponite loading. At low GA/Laponite ratios (approximately 10(-6) M of gallic acid per gram of clay), gallic acid is adsorbed at the variable charge sites of Laponite. This adsorption can be adequately described by surface complexation modeling. At higher GA/Laponite ratios (approximately 10(-3) M of gallic acid per gram of clay), X-ray diffraction data show that gallic acid is intercalated at the interlamellar sites of Laponite. In the presence of Pb2+ ions, the formed GA/Pb complex is associated with Laponite in an analogous structural manner, that is, adsorption at variable charge sites or intercalation at the interlamellar sites of Laponite, depending on the loading. Laponite stabilizes the GA/Pb radicals. At prolonged exposure to ambient O2, Laponite promotes the formation of stable oligomeric GA/Pb radical species, which are intercalated into interlamellar sites.     

没食子酸磁性表面分子印迹聚合物的制备与选择性识别性能

羟基苯甲酸类化合物用途广泛,极性较强,在复杂水溶液体系中这些类似物的分离纯化与分析非常困难。 本文以磁性Fe₃O₄纳米颗粒为载体,没食子酸(GA)为模板分子,制备了磁性表面分子印迹聚合物(MIP)。 利用透射电子显微镜、红外光谱、磁强测定等检测手段对MIP进行了结构表征。 并对其吸附性能进行研究,比较了该MIP对GA及其它3种结构类似物的吸附性能差异。 结果表明,制备的以GA为模板的磁性分子印迹聚合物为核壳球形结构,键合牢固,对GA的吸附动力学符合准二级动力学方程模型,吸附过程属于Langmuir单分子层吸附。 该聚合物对GA表现出优异的选择性识别能力,其吸附量(318 K时37.736 mg/g)远远高于结构类似物。 该磁性分子印迹聚合物对模板分子不仅具有特异识别能力,而且能够磁控分离,分离效率高,可用于固相萃取。     

Interfacial thermodynamics of gallic acid adsorption on a chargeable hydrophobic surface

The thermodynamics of adsorption of gallic acid (GA, 3,4,5-trihydroxylbenzoic acid) on the hanging mercury drop electrode (HMDE) surface was studied by temperature-dependent stripping voltammetry (TD-SV), at physiological pH 7.4. The thermodynamic parameters, e.g., Gibbs free energy, ΔG(ADS), enthalpy, ΔΗ(ADS) and entropy, ΔS(ADS), of adsorption have been determined at physiological temperatures 2-40 °C. Chemisorption of the radical species ≡[GA(OH)(2)(O(-))]* is the energetically important reaction. The thermodynamic data show a complex mechanism of adsorption of GA on the electrode surface, which is strongly dependent on temperature. At low-temperatures T<12 °C, adsorption is controlled by enthalpy, while at T>22 °C, adsorption is entropy driven. In the temperature range 12 °C and 22 °C, a combined enthalpy-entropy stabilization occurs. A mechanism is proposed which analyses the implication of thermodynamics to the interfacial adsorption of polyphenols with cell membranes under physiological conditions.     

Influence of some organic ligands on the adsorption of lead by agricultural soil

The adsorption of lead onto agricultural soil in the presence of organic compounds such as, humic acid, gallic acid or phenol was studied. The study included the factors affecting the adsorption process such as contact time, pH, adsorbent dose, metal concentration and organic ligands concentration. The experimental isotherm data were found to fit both Langmuir and Freundlich isotherms. The results show that the pseudo second-order equation provides the best correlation for the adsorption process. The results indicate that both humic acid and phenol increase the adsorption of lead while gallic acid slightly decreases the adsorption.     

没食子酸在电活化玻碳电极上的电化学行为及测定

采用循环伏安法和线性扫描伏安法对没食子酸在电活化玻碳电极上的电化学行为进行了研究。玻碳电极在pH7.0的磷酸盐缓冲溶液中,用恒电位法在1.7 V电位阳极氧化400 s。然后在pH3.0的柠檬酸盐缓冲溶液中,没食子酸在0.479 V和0.442 V处有一良好的氧化还原峰,在0.02～0.40 V s-1范围内,其氧化峰电流与扫描速率呈良好线性关系,表明电极过程为受吸附控制的准可逆过程。线性循环伏安法的氧化峰电流与没食子酸浓度1×10-6～1×10-4mol L-1范围内呈良好的线性关系(r=0.980 6),检出限为7.6×10-7mol L-1(S/N=3)。该方法操作简便,重现性较好,并应用此法分析了健民咽喉片剂中的没食子酸的含量。     

Adsorption of humic substances by macro weakly basic ion-exchange resin and their effects on removal of Cu2+ and Pb2+

<正>Adsorption ofhumic,tannic and gallic acids by a macro weakly basic ion-exchange resin JN-01 was studied.The adsorption capacity of this resin for gallic and tannic acids is much higher than that for humie acid,which can be explained on the basis of both their molecular size and ionization degree.Furthermore,humic acid is separated into different components with molecular weight in the range from 2000 Da to 100000 Da by ultra-filter,and their adsorption isotherms on resin JN-01 indicate that humic acid's molecular weight is an important factor which makes significant influence on adsorption.Finally,changes in the amount of Cu~(2+) and Pb~(2+) adsorbed on resin JN-01 as a function of the concentration of each of these three acids were studied.A large increase in the heavy metal ions uptake is observed in the presence of humic substance,such advantages are due to the interactions between the heavy metal ions and the unbound functional groups of the adsorbed organic acids.     

Characterization of Gallic Acid Interaction with Human Serum Albumin by Spectral and Molecular Modeling Methods

The binding of drugs with human serum albumin(HSA)is a crucial factor influencing the distribution and bioactivity of drugs in the body.To understand the action mechanisms between gallic acid(GA,3,4,5-...     

Stabilization of antioxidant gallate in layered double hydroxide by exfoliation and reassembling reaction

As for the stabilization of chemically sensitive bioactive molecule in this study, gallic acid (GA) with antioxidant property was intercalated into interlayer space of layered double hydroxide (LDH), which was realized by exfoliation and reassembling reaction. At first, the pristine nitrate-type Zn₂Al-LDH in solid state was synthesized via co-precipitation followed by the hydrothermal treatment at 80 °C for 6 h, and then exfoliated in formamide to form a colloidal solution of exfoliated LDH nanosheets, and finally reassembled in the presence of GA to prepare GA intercalated LDH (GA-LDH) desired, where the pH was adjusted to 8.0 in order to deprotonate GA to form gallate anion. According to the XRD analysis, GA-LDH showed well-developed (00l) diffraction peaks with a basal spacing of 1.15 nm, which was estimated to be larger than that of the pristine LDH (0.88 nm), indicating that gallate molecules were incorporated into LDH layers with perpendicular orientation. From the FT-IR spectra it was found that gallic acid was completely deprotonated into gallate, and stabilized in between LDH lattices via electrostatic interaction. The content of GA in GA-LDH was determined to be around 23 wt% by UV–vis spectroscopic study, which was also confirmed by HPLC analysis. According to the in-vitro release of GA out of GA-LDH in PBS solution (pH 7.4) at 4 °C, GA was sustainably released from GA-LDH nanohybrid up to 86% within 72 h. The antioxidant property of GA-LDH was almost the same with that of intact GA which was examined by DPPH. The photostability of GA-LDH under UV light irradiation was immensely enhanced compared to intact GA. It is, therefore, concluded that the present GA-LDH nanohybrid can be considered as an excellent antioxidant material with high chemical- and photo-stabilities, and controlled release property.