层析聚酰胺树脂对茶多酚的吸附热力学和吸附动力学研究

通过静态吸附实验,研究了温度对聚酰胺树脂吸附茶汤中茶多酚的影响,探讨了吸附的热力学和动力学规律.结果表明,升高温度会降低聚酰胺树脂的饱和吸附量,但会提高初始吸附速率.等温吸附规律可用Freundlich和Langmuir方程表示,吸附过程为熵驱动的放热、熵增的自发过程,属化学吸附范畴,吸附作用力主要是氢键.吸附动力学规律可用Lagergren一级速率方程表示,以颗粒内扩散为主.     

木犀草素在C_(60)衍生物修饰电极上的电化学行为

将新型的C_(60)吡咯烷衍生物(FPD)的异构体之一修饰于玻碳电极表面,通过循环伏安法研究了木犀草素在FPD/GCE上的电化学行为,结果显示该电极对木犀草素的氧化还原过程具有良好的电催化活性。在最优实验条件下,在2×10~(-8)mol/L~10~(-5)mol/L浓度区间范围内,氧化峰电流与木犀草素的浓度呈线性关系,其线性方程为:I_(pc)=-0.0103C-3.5955(R~2=0.9901),检测限为6.6×10~(-9) mol/L。表明所制备的修饰电极对木犀草素的测定具有较高的灵敏度和良好的选择性。     

HPD-100大孔吸附树脂与聚酰胺吸附黄酮的对比研究

对比研究了HPD-100大孔吸附树脂与聚酰胺吸附树脂对总黄酮的静态和动态吸附性能,考察影响吸附的主要因素。结果表明,Freundlich等温方程较Langmuir等温方程更适宜描述树脂对总黄酮的吸附,聚酰胺树脂的方程拟合更好。黄酮溶液的浓度及流速对HPD-100的吸附影响不大,吸附率均高达90%以上,相同条件下,聚酰胺树脂只有其80%左右。而解吸剂流速对HPD-100解吸的影响则相反,只有聚酰胺树脂的80%左右。两种树脂对于黄酮的吸附解析总过程无明显差异。     

HPD-100大孔吸附树脂与聚酰胺吸附黄酮的对比研究

对比研究了HPD-100大孔吸附树脂与聚酰胺吸附树脂对总黄酮的静态和动态吸附性能,考察影响吸附的主要因素。结果表明,Freundlich等温方程较Langmuir等温方程更适宜描述树脂对总黄酮的吸附,聚酰胺树脂的方程拟合更好。黄酮溶液的浓度及流速对HPD-100的吸附影响不大,吸附率均高达90%以上,相同条件下,聚酰胺树脂只有其80%左右。而解吸剂流速对HPD-100解吸的影响则相反,只有聚酰胺树脂的80%左右。两种树脂对于黄酮的吸附解析总过程无明显差异。     

聚酰胺吸附硝基苯酚的热力学与机理探讨

探讨了水溶液中聚酰胺树脂吸附硝基苯酚的热力学特性及其机理，测定了不同温度下的吸附等温线。结果表明：在稀溶液中吸附硝基苯酚均符合Freundlich或Langmuri模型；聚酰胺对苦味酸、2，4—二硝基苯酚的吸附为熵驱动的吸热、熵增的自发过程；对对硝基苯酚的吸附为焓驱动的放热、熵减的自发过程；硝基苯酚主要以酚羟基及邻位硝基与聚酰胺中的酰胺基形成氢链吸附；吸附过程均具有物理吸附特征，主要为氢链吸附和范德华吸附。     

木犀草素分子印迹聚合物的合成

以木犀草素为模板分子,偶氮二异丁腈为引发剂,丙烯酰胺为功能单体,N,N-亚甲基双丙烯酰胺为交联剂,在极性溶剂中合成了木犀草素分子印迹聚合物(LMIP)。考察了溶剂用量及种类和功能单体对合成的影响,得到了最佳合成工艺条件,简化了模板分子的洗脱工艺。红外光谱分析表明:洗脱前分子印迹聚合物中原木犀草素在1 270 cm-1处的O—H吸收峰移至1 300 cm-1处,说明模板分子被功能单体、交联剂经聚合交联固定在聚合物中,洗脱后该峰完全消失;扫描电子显微镜观察发现:洗脱后的分子印迹聚合物表面凹凸不平,产生了大量吸附模板分子的空穴。探讨了LMIP的吸附特性,用与木犀草素结构相似的槲皮素作对比实验,分子印迹聚合物对木犀草素的吸附量(33.653μmol/g)明显高于槲皮素的吸附量(8.654μmol/g),表明LMIP对模板分子具有较高的吸附选择性。     

木犀草素配位印迹聚合物的制备及吸附性能

采用沉淀聚合法,结合Zn2+的配位作用,在水溶液中制备了木犀草素配位印迹聚合物(LUT-CIPs),并考察了LUT-CIPs的吸附性能。结果表明,LUT-CIPs的最佳制备条件为:n〔模板分子(木犀草素-Zn2+)〕∶n〔功能单体(丙烯酰胺)〕∶n〔交联剂(N,N?-亚甲基双丙烯酰胺)〕=1∶4∶30。在该条件下聚合物对醇相中的木犀草素的吸附量达36.45 mg/g、对芹菜素和芸香叶苷竞争底物的选择性系数分别达到5.09和3.35;木犀草素在LUT-CIPs的吸附过程符合Freundlich等温吸附模型和准二级动力学方程;吸附液中加入的14种金属盐均可提高LUT-CIPs的吸附容量,金属离子和酸根离子种类对吸附有影响,其中加入Pb(Ac)2后吸附容量提高最明显,为加入Zn(Ac)2的2.48倍、未加金属盐的5.20倍。     

木犀草素在纳米NiOx/单壁碳纳米管修饰玻碳电极上的电化学行为

采用电沉积法结合表面滴涂法制备了纳米氧化镍/单壁碳纳米管修饰玻碳电极(NiO_x/SWCNTs/GCE),通过循环伏安法、扫描电子显微镜对修饰电极进行了表征,运用方波伏安法和循环伏安法研究了木犀草素在NiO_x/SMWCNTs/GCE修饰电极上的电化学行为。结果表明,电极表面纳米氧化镍和单壁碳纳米管的存在对木犀草素具有良好的电催化活性,电极稳定性高,表面可以更新。在pH 2.8±0.2的伯瑞坦-罗宾森缓冲溶液中,木犀草素在NiO_x/SWCNTs/GCE修饰电极上的氧化、还原峰电位均负移,峰电流明显增加,据此,建立了测定木犀草素的方法。在-0.2～0.6 V电位区间内,在方波伏安曲线上的还原峰电位E为0.43 V,峰电流I木犀草素浓度在2.4×10~(-6)～1.0×1.0~(-10) mol/L范围内与电位有良好的线性关系,线性回归方程为I=5.39×10~6c+4.171 6,R~2=0.999,检出限(3S/N)为3.4×10~(-11) mol/L,此方法用于砂珍棘豆中木犀草素含量的测定。样品回收率为98.69%～104.40%,相对标准偏差为1.05%～1.37%。     

木犀草素温敏分子印迹聚合物的合成及性能研究

以木犀草素为模板分子、丙烯酰胺为功能单体、N,N-亚甲基双丙烯酰胺为交联剂、N-异丙基丙烯酰胺为温敏单体,采用沉淀聚合法制备木犀草素温敏分子印迹聚合物。扫描电镜观察聚合物形貌,表明印迹空穴的存在。不同温度下吸附及洗脱实验证明所得印迹材料具备较好的特异性吸附性能及温度响应行为,可为天然药物中黄酮类木犀草素成分的提取分离提供新思路与新方法。     

木犀草素合成研究进展

木犀草素具有重要的生理活性,应用广泛。文章根据合成工艺所用起始原料的不同,将合成路线分为全合成和半合成两大类,分别介绍了各合成路线。其中半合成路线具有收率高、步骤简单等优点,具有生产开发价值,值得进一步深入研究。     

柱撑膨润土对刚果红的吸附热力学与吸附动力学研究

制备了铝柱撑膨润土,研究其对废水中刚果红的吸附性能.利用X射线衍射(XRD)和傅里叶红外光谱分析仪(FTIR)对其进行表征.考察了投加量和pH值对吸附性能的影响,研究了吸附热力学和动力学规律.结果表明,pH值在3～7时,脱色率较高;在投加量为5 g/L,溶液为原始pH值时,对浓度为50 mg/L的废水,脱色率可达98.2％;柱撑膨润土对刚果红的吸附符合准二级动力学模型和Langmuir方程,吸附为自发放热物理过程.     

阴离子交换树脂对茶氨酸的吸附动力学和热力学

以酶法制备茶氨酸,研究了碱性条件下阴离子交换树脂对茶氨酸的吸附与分离. 结果表明,强碱性树脂对茶氨酸的吸附性能优于弱碱性树脂,且其吸附容量受pH值的影响较小,pH=9.0时凝胶型强碱性树脂HZ202对茶氨酸的平衡吸附量可达96.3 mg/g. 对HZ202吸附茶氨酸的吸附等温模型及动力学、热力学参数进行了分析,结果表明,茶氨酸在HZ202树脂表面为非均一分布,Spis模型可较好模拟其吸附等温线数据;热力学参数计算结果显示,不同温度下吸附过程的吉布斯自由能变DG均为负值,表明吸附为自发的放热过程;吸附过程的焓变DH=20.9~418.4 kJ/mol,可判断其为化学吸附. 茶氨酸吸附过程符合准二级动力学方程,吸附过程受化学反应控制,提高茶氨酸初始浓度可提高吸附速率.     

Equilibrium Isotherms,Thermodynamics, and Kinetic Studies for the Adsorption of Food Azo Dyes onto Chitosan Films

The adsorption of FD&C red 2 and FD&C yellow 5 onto chitosan films (CFs) was evaluated by equilibrium isotherms, thermodynamics, and kinetic studies. The effects of temperature (298–328 K), initial dye concentration (50–300 mg L^?1), stirring rate (50–350 rpm), and contact time (0–120 min) were investigated at pH of 2.0 and 100 mg L^?1 of CFs. The dye concentration was determined by spectrophotometry. Freundlich and Langmuir models were used to represent the equilibrium data. The Langmuir model was the more adequate to represent the equilibrium data (R² > 0.99 and average relative error <2.50%) and the maximum adsorption capacities were 494.13 and 480.00 mg g^?1 for FD&C red 2 and FD&C yellow 5, respectively, obtained at 298 K. The R_L values ranged from 0.044 to 0.145. The adsorption was exothermic, spontaneous, and favorable. For the FD&C red 2, 90% of saturation was attained at 120 min and the Elovich model was the more appropriate. For the FD&C yellow 5, 95% of saturation was attained at 20 min and the pseudo first-order model was the more adequate to fit the kinetic data. CFs were easily separated from the liquid phase after the adsorption process, providing benefits for industrial applications, and its application range can be extended for azo dyes.     

螯合树脂对铜离子的吸附动力学和热力学

针对以谷氨酰胺-铜(II)配合物为供体酶法制备茶氨酸体系,研究了D401螯合树脂对Cu2+的吸附,探讨了吸附过程的热力学和动力学,通过红外光谱鉴定了树脂的配位结构. 结果表明,树脂吸附量随离子浓度和温度升高而增加,当pH为5.6时吸附量最大,达1.887 mmol/g. 不同温度下Langmuir方程均呈现很好的拟合度. 热力学平衡方程计算得DG<0, DH=21.5 kJ/mol, DS>0,表明该吸附过程是自发的、吸热、熵增加的过程. 动力学研究表明,该过程符合准二级动力学模型,吸附反应速率由颗粒扩散和液膜扩散共同控制. 该树脂在较宽的pH范围内对Cu2+具有很好的选择吸附性,可用于酶转化茶氨酸体系中Cu2+的去除.     

交联木质素磺酸钠的制备及吸附动力学

以木质素磺酸钠为原料,环氧氯丙烷为交联剂,制备了交联木质素磺酸钠吸附材料。采用红外光谱(FT-IR)和X-射线衍射(XRD)对吸附材料进行表征,用原子吸收光谱测定其对Cu~(2+)的吸附性能。结果表明,木质素磺酸钠通过环氧氯丙烷成功交联。吸附性能分析表明,吸附动力学过程符合准二级动力学模型,平衡吸附量为109.2 mg/g。     

Isotherm,Thermodynamics, and Kinetics of Methyl Orange Adsorption onto Magnetic Resin of Chitosan Microspheres

Severe environmental pollution problems arising from toxic dyestuffs (e.g., methyl orange) are receiving increasing attention. Therefore, dyes’ safe removal has become a research hotspot. Among the many physical–chemical removal techniques, adsorption using renewable biological resources has proved to be more advantageous over others due to its effectiveness and economy. Chitosan is a natural, renewable biopolymer obtained by deactivated chitin. Thus, the magnetic resin of chitosan microspheres (MRCM), prepared by reversed-phase suspension cross-linking polymerization, was used to remove methyl orange from a solution in a batch adsorption system. The main results are as follows: (1) The results of physical and swelling properties of MRCM indicated that MRCM was a type of black spherical, porous, water-absorbing, and weak alkali exchange resin, and it had the ability to adsorb methyl orange when it was applied in solutions above pH 2.0. (2) In batch adsorption studies, the maximum adsorption capacity was obtained at pH 5; the adsorption equilibrium time was 140 min; and the maximum adsorption was reached at 450 mg/L initial concentration. (3) Among the three isotherm adsorption models, Langmuir achieved the best fit for the adsorption of methyl orange onto MRCM. (4) The adsorption thermodynamics indicated that the adsorption was spontaneous, with increasing enthalpy, and was driven by the entropy. (5) The pseudo-second-order kinetics equation was most suitable to describe the adsorption kinetics, and the adsorption kinetics was also controlled by the liquid–film diffusion dynamics. Consequently, MRCM with relatively higher methyl orange adsorption exhibited the great efficiency for methyl orange removal as an environment-friendly sorbent. Thus, the findings are useful for methyl orange pollution control in real-life wastewater treatment applications.     

Development of a First-Order Kinetics Based Model,Equilibrium Studies,and Thermodynamics for the Adsorption of Methyl Orange onto a Lignocellulosic Anion Exchanger

The present article describes the adsorption behavior of methyl orange (MO) on polyacrylamide-grafted aminomethylated tamarind fruit shell anion exchanger. The optimum pH for MO removal was 3.0 and the equilibrium was attained within 2 h. The kinetic and isotherm data obtained at different pH and temperatures, could be fitted with the pseudo-first-order rate equation and the Sips isotherm model, respectively. The adsorption process was exothermic and spontaneous in nature. The decrease in isosteric heat of adsorption with increasing MO uploading on the adsorbent reflects the surface energetic heterogeneity of the adsorbent. The reusability of the adsorbent was demonstrated over 4 cycles using 0.2 M NaOH as the desorbing agent.