2-巯基苯并噻唑直接键合硅胶的制备及其对Cu（Ⅱ）的吸附性能研究

采用一种简单有效的方法合成了2-巯基苯并噻唑(MBT)直接键合硅胶.将键合硅胶用于水中Cu(Ⅱ)的吸附,考查了溶液pH值的影响.结果表明当pH为6时,键合硅胶的吸附量最大.通过分批实验,研究了278K、293K和308K 3个温度条件下的吸附平衡.应用Langmuir和Freundlich两个双参数等温线模型进行拟合,MATLAB软件的误差分析表明,Freundlich模型与实验数据更加吻合.计算得到吸附过程的热力学参数△G°、△H°和△S°的值分别为-21.90kJ/mol(293K)、14.57kJ/mol和124.61J/(mol·K).结果表明,键合硅胶对Cu(Ⅱ)的吸附是一个自发进行的吸热过程.     

新型离子交换树脂CG-6对人凝血酶原复合物的吸附行为分析及研究

根据人凝血酶原复合物(Prothrombin Complex Concentrate,以下简称PCC)的性质,对合成的大孔阴离子交换树脂进行静态吸附研究,并与已经商品化的DEAE Sephadex A50、Streamline DEAE凝胶型离子交换树脂进行比较,筛选出吸附性能较优的CG-6树脂.通过静态吸附实验,测定了CG-6对PCC在不同温度下的吸附等温线、考察了吸附过程中的动力学和热力学行为并初步探讨了吸附机理.结果表明,吸附动力学可用拟二级速率方程来描述,计算值与实测值吻合较好.CG-6对PCC的吸附等温线可分为两段,在较低的平衡浓度下,吸附平衡符合Langmuir方程,温度的升高有利于平衡吸附量的增大,表明该吸附反应为一吸热过程.求出反应的焓变△H=115.1kJ/mo1,熵变△S分别为2.37J/mol·K(5℃)、20.97 J/mol·K(15℃)、23.11J/mol·K(20℃)、37.32J/mol·K(30℃),吉布斯自由能变化△G分别为-0.54kJ/mol(5℃)、-5.93kJ/mol(15℃)、-6.66kJ/mol(20℃)、-11.20kJ/mol(30℃).此外,除了离子交换,CG-6对PCC也有物理吸附现象.     

活性白土对油脂溶液中β-胡萝卜素的吸附热力学及动力学研究

探讨了活性白土(AAB)对油脂溶液中β-胡萝卜素的吸附热力学及动力学特征,AAB对β-胡萝卜素的吸附行为可用Langmuir和Freundlich等温式进行描述,相关性均较好,在高温条件下(75～95℃),AAB对β-胡萝卜素的吸附更符合Freundlich模型的吸附行为.分别采用拟一级反应乖拟二级反应模型描述了吸附动力学数据,表明AAB吸附β-胡萝卜素适合于拟二级吸附动力学行为,且高温有利于提高吸附量和吸附速率.AAB对β-胡萝卜素的吸附表现活化能E_a为38.673kJ/mol,表明整个吸附过程涉及到化学吸附作用;通过对吸附热力学参数△H、△S及△G的分析,表明吸附过程是自发进行且伴随着吸热及熵值的增加,吸附趋势随着温度的升高而有所增大.     

大孔丙烯酸树脂对镧元素的静态与动态吸附研究

研究了大孔丙烯酸树脂(MAR)对镧离子的吸附与解吸行为.静态吸附研究pH值、接触时间和温度对吸附的影响.结果表明,大孔丙烯酸树脂可以有效地将镧离子从水溶液中去除.吸附平衡的时间为14 h.在308 K时,缓冲液pH值6.50,由Langmuir等温线模型得出大孔丙烯酸树脂对镧离子的最大吸附量是379 mg·g-1.吸附过程符合液膜扩散动力学(k=4.37×10-5～5.06×10-5s1).与Freundlich等温线相比,吸附过程更符合Langmuir等温线模型.吸附热力学参数分别为:△H=16.7 kJ·mol-1,△S=130 J·(mol·K)-1,△C298K=-22.0 kJ·ml-1.托马斯模型用于确定动态吸附的特征参数以及预测突破曲线.镧离子可以用浓度为0.5 mol·L-1的HCl溶液洗脱.利用红外光谱技术对大孔丙烯酸树脂的表面进行吸附前与吸附后的表征.     

纳米TiO2去除氟离子的性能

研究了锐钛型纳米TiO2吸附剂对氟离子的吸附行为,考察了吸附平衡时间、温度、溶液的pH值等因素对吸附过程的影响.结果表明,纳米TiO2对氟离子的吸附在2.0 min基本达到平衡,在pH值2.0～10.0范围内,吸附率大于97％;吸附的氟离子可用0.1 mol/L NaOH溶液洗脱,3.0 min基本达到解析平衡,解析率能达到96％;该吸附过程符合准二级反应动力学模型,其反应的表观活化能(Ea)为6.85 kJ/mol;颗粒内扩散过程为吸附控制步骤,但不是唯一的控制步骤,同时还受液膜扩散的影响;吸附过程符合Langmuir、D-R等温模型,常温下纳米TiO2对氟离子的平均吸附能为4.26 kJ/mol.吸附反应的△G0＜0,焓变△H0＞0,说明该吸附过程是自发的吸热反应.共存阴离子HCO3-和pO43-对氟离子的吸附有影响.纳米TiO2在动态和静态吸附实验中的除氟效果相近.     

717型阴离子交换树脂吸附水溶性芳香族有机污染物研究

研究了717型阴离子交换树脂对苯酚、苯甲酸和十二烷基苯磺酸钠(SDBS)等水溶性芳香族污染物吸附过程的基本化学问题.研究结果表明:717型树脂对苯酚、苯甲酸和SDBS的吸附过程均符合Lagergren二级吸附动力学方程,吸附速率均随着温度的升高而加快,吸附表观活化能Ea分别为13.2kJ/mol、59.5kJ/mol和48.1kJ/mol,吸附过程△H0和△S0均为正值,△G0均为负值,吸附能够自发进行;吸附等温模型符合Langmuir等温式;318K时,717型树脂在pH=9.1对SDBS的饱和吸附容量为360mg/g;在pH=10.2,对苯酚和苯甲酸的饱和吸附容量分别为194mg/g和286mg/g.用浓度均为0.5mol/L,体积比为5∶1的NaCl-NaOH混合溶液可快速洗脱树脂上吸附的污染物,洗脱率达98％以上.该树脂对水溶性芳香族污染物吸附容量大,易于再生和循环利用,可用于环境水体中水溶性芳香族有机污染物的吸附治理.     

D160大孔吸附树脂对染料木黄酮吸附性能的研究

研究了D160大孔吸附树脂对染料木黄酮的吸附性能.结果表明,在pH4.00时,该树脂对染料木黄酮有较好的吸附性能;静态饱和吸附容量为64.5mg/g树脂;用95%乙醇溶液作解吸剂,二次累计解吸率接近100%;表现速率常数k298=1.01×10-4s-1;测得吸附热力学参数分别为:△H=32.2kJ/mol,△S=119J/(mol·K),△G288=-2.03kJ/mol,△G298=-3.22kJ/mol,△G308=4.41kJ/mol.等温吸附服从Freundlich和Langmuir等温吸附规律;研究还表明,提高振荡频率对吸附有利.     

D301大孔树脂吸附钒(V)的性能研究

研究了D301大孔树脂对钒的吸附性能.结果表明,pH值对D301树脂吸附钒的影响很大,与钒在溶液中的赋存状态有关,且在pH=2时吸附效果最好:测得吸附热力学参数分别为:△H=8.97kJ/mol,△G_(313)=-5.69kJ/mol,△G_(303)=-5.2kJ/mol,△G_(293)=-4.9kJ/mol,△S=46.84J/mol·K.等温吸附服从Freundlich经验式;考察了溶液浓度、搅拌速率对交换过程的影响,并对实验数据运用相关理论模型进行拟合,结果显示钒(V)在D301树脂上吸附交换过程控制步骤为颗粒扩散控制,反应级数n为0.2391.     

一种球形木质素吸附剂对L-天门冬氨酸的吸附行为研究

以硫酸盐木质素为原料,利用反相悬浮技术制备出球形木质素吸附剂.通过静态吸附试验,研究了球形木质素吸附剂对L-天门冬氨酸的吸附动力学和热力学特性,探讨了pH对吸附过程的影响.结果表明,当溶液pH值为3.0时,SLA的平衡吸附容量为518.0mg/g,球形木质素吸附剂对L-天门冬氨酸的吸附速率同时受液膜扩散和颗粒内扩散过程控制.吸附符合Langmuir和Freundlich等温吸附方程.且焓△H-16.81kJ/mol,表明该吸附反应是以吸热的化学吸附过程为主,活化能Ea=3.3406kJ/mol,说明球形木质素吸附剂的吸附过程是以颗粒内扩散为主.     

纳米TiO_2粒径、孔径对酸性紫43吸附动力学与热力学行为的影响

探究锐钛型纳米TiO2粒径(5-10、25、40、60、100nm)及孔径(96,120,134,143,52)对染料废水(酸性紫43)吸附动力学与热力学行为的影响。假二级方程和准一级方程分别能准确描述TiO2粒径≤100nm吸附动力学过程。经Weber-Morris和Dumwald-Wagner扩散模型分析,吸附速率由膜扩散和内扩散共同控制并受粒径影响。吸附热力学符合Langmuir等温吸附方程,最大吸附量(Qmax)与孔径正相关,与粒径无关,60nm TiO2孔径最大,吸附效果最好,Qm可达104.17mg/g;参数40kJ/mol△H0,吉布斯自由能△G0,受温度影响不大,说明吸附过程是自发的吸热反应,以物理吸附为主。     

Thermal degradation of epoxy-silica organic-inorganic hybrid materials

Degradation kinetics of organic-inorganic hybrid materials based on epoxy resin were investigated by thermogravimetric analysis (TGA). The hybrid materials were prepared from diglycidyl ether of bisphenol A (DGEBA) and 3-glycidyloxypropyltrimethoxysilane (GLYMO) polymerised simultaneously by poly(oxypropylene)diamine (Jeffamine D230). Nanometric level of homogeneity in the hybrids was verified by electron microscopy. Energy of activation of degradation for the hybrids with varying inorganic content, as well as for the unmodified epoxy-amine system, was determined by the isoconversional Kissinger-Akahira-Sunose method, and was found to be significantly higher for the hybrid materials than for the unmodified epoxy-amine system. The degradation process was described by empirical kinetic models. The results indicated that presence of the inorganic network influences the mechanism of degradation of organic phase. Greater thermal stability of hybrid materials was confirmed by other parameters obtained from TGA curves.     

Study of the thermal degradation of bioactive sol–gel coatings for the optimization of its curing process

A set of materials has been prepared by sol–gel process containing different quantities of hydroxyapatite (0, 2.5 and 5% HAp w/w) using as silica precursors glycidyloxypropyltrimethoxysilane (GPTMS) and triethoxyvinylsilane (VTES). In order to optimize the curing process to obtain sintherized systems (inorganic network) or hybrid systems (organic–inorganic) a TG and FTIR studies have been developed and degradation kinetic triplet parameters were obtained (the activation energy, pre-exponential factor, and function of degree of conversion). The kinetic study was analyzed by means of an integral isoconversional non-isothermal procedure (model free), and the kinetic model was determined by the Coats–Redfern method and through the compensation effect (IKR). All the systems followed the n = 6 kinetic model. The addition of HAp increases the thermal stability of the systems. The isothermal degradation was simulated from non-isothermal data, and the curing process could be defined to obtain the two types of materials. Temperature under 250 °C allows the formation of hybrids networks.     

ZnO/C纳米球的亚甲基蓝单吸附特性:平衡、动力学及机理

采用电弧放电法制备了ZnO/C纳米球,利用FESEM、XRD和N₂吸附/脱附测试进行了表征。在避光条件下研究了复合材料对亚甲基蓝的吸附性能。研究结果表明,随着亚甲基蓝的浓度及接触时间的增长吸附量明显上升,在吸附时间为150 min时达到吸附平衡。采用Langmuir、Freundlich及Temkin等温吸附模式对吸附平衡进行了研究。结果表明,吸附等温线符合Langmuir等温吸附模式,单层吸附饱和容量可达188.68 mg·g^-1。利用动力学模型、内扩散模型和外扩散速率控制模型拟合实验数据,拟合数据表明其动力学符合伪二级动力学模型;内扩散机理不是吸附速率的唯一限制机理,亚甲基蓝的总吸附速率受膜扩散控制。     

ZnO/C纳米球的亚甲基蓝单吸附特性:平衡、动力学及机理

采用电弧放电法制备了ZnO/C纳米球,利用FESEM、XRD和N₂吸附/脱附测试进行了表征。在避光条件下研究了复合材料对亚甲基蓝的吸附性能。研究结果表明,随着亚甲基蓝的浓度及接触时间的增长吸附量明显上升,在吸附时间为150 min时达到吸附平衡。采用Langmuir、Freundlich及Temkin等温吸附模式对吸附平衡进行了研究。结果表明,吸附等温线符合Langmuir等温吸附模式,单层吸附饱和容量可达188.68 mg·g^-1。利用动力学模型、内扩散模型和外扩散速率控制模型拟合实验数据,拟合数据表明其动力学符合伪二级动力学模型;内扩散机理不是吸附速率的唯一限制机理,亚甲基蓝的总吸附速率受膜扩散控制。     

PMMA/SiO_2/OV-POSS杂化材料的制备与表征

以乙烯基三氯硅烷为原料水解制得八乙烯基多面体低聚倍半硅氧烷(OV-POSS),将其与经KH570改性的SiO2溶胶和甲基丙烯酸甲酯(MMA)混合均匀,采用热固化的方法制得PMMA/SiO2/OV-POSS杂化材料,通过透射电镜、红外谱图、差热分析和热重分析对材料的微观结构以及热性能进行表征,结果表明:杂化材料结构均匀,有机相和无机相之间通过双键聚合的方式形成了共价键;杂化材料耐热性好,玻璃化转变温度比纯PMMA提高约72℃,分解温度提高约121℃。     

Structural diversity and chemical trends in hybrid inorganic-organic framework materials

Hybrid framework compounds, including both metal-organic coordination polymers and systems that contain extended inorganic connectivity (extended inorganic hybrids), have recently developed into an important new class of solid-state materials. We examine the diversity of this complex class of materials, propose a simple but systematic classification, and explore the chemical and geometrical factors that influence their formation. We also discuss the growing evidence that many hybrid frameworks tend to form under thermodynamic rather than kinetic control when the synthesis is carried out under hydrothermal conditions. Finally, we explore the potential applications of hybrid frameworks in areas such as gas separations and storage, heterogeneous catalysis, and photoluminescence.     

Multistep adsorption of anionic dyes on silica/chitosan hybrid. 1. Comparative kinetic data from liquid- and solid-phase models

In this work, a hybrid silica/chitosan was synthesized and characterized by nitrogen elemental analysis and thermal analysis (TG, DTG, DTA, and DSC) and BET surface area. The hybrid was used in adsorption studies of two anionic dyes from aqueous solutions. A rise of temperature accelerates mass transfer of dyes into the hybrid. However, the maximum adsorption capacities reach similar values from 25 to 55 degrees C. The kinetic data were first evaluated in relation to the decrease of the time-related residual concentration of the dyes in solution, where the second-order model has presented the best fitting. The solid-phase interaction of dye data presents a rough fitting to the traditional first-order Lagergren kinetic model. However, a modified Avrami kinetic equation was successfully fitted to the kinetic quantities, where from five to seven kinetic regions were found. A pore-diffusion model has also demonstrated that the diffusion is the rate-controlling interaction mechanism. However, the experimental-calculated comparative values are the best way to evaluate a specific aqueous- or solid-phase kinetic model.     

Flow‐through immobilized enzyme reactors based on monoliths: II. Kinetics study and application

In the last decade, the application of monolithic materials has rapidly expanded to the realization of flow‐through bioconversion processes. Up to these days, different classes of enzymes such as hydrolases, lyases, and oxidoreductases have been immobilized on organic, inorganic, or hybrid monolithic materials to prepare the effective flow‐through enzymes reactors for application in proteomics, biotechnology, pharmaceutics, organic synthesis, and biosensoring. Current review describes the results of kinetic study and specialties of flow‐through immobilized enzyme reactors based on the existing monolithic materials.     

烷氧基硅烷溶胶-凝胶反应机理

利用烷氧基硅烷作为前驱体之一,进行溶胶-凝胶(sol-gel)反应制备无机氧化物和有机－无机杂化材料,近几十年来一直是一个研究热点。对烷氧基硅烷的sol-gel反应过程,特别是起始的水解和初步缩合过程已有较多的研究。本文综述了烷氧基硅烷的sol-gel反应机理研究的进展,并对未来发展提出了看法。     

Real‐time Fourier transform infrared study of the free‐radical ultraviolet‐induced polymerization of a hybrid sol–gel. II. The effect of physicochemical parameters on the photopolymerization kinetics

Free‐radical photocurable hybrid sol–gel materials have gained special interest during the last decades. Compared to thermally processed materials, they present the advantages of fast curing, low energy consumption, and spatiotemporal control of the reaction. Although comprehension of the photochemical step is fundamental, little is known about the characteristic of photochemistry in this kind of material. Real‐time Fourier transform infrared spectroscopy was used to study the photopolymerization of a hybrid sol–gel upon ultraviolet irradiation. Various photoinitiator systems were tested for their efficiency in inducing the polymerization of pendant polymerizable moieties anchored on a partially condensed silicate network. The presence of O₂ and the nature of the polymerizable function were shown to be crucial factors in the photoinduced process. The effects of the photoinitiator concentration and light intensity were also studied. These results were explained in terms of classical kinetic models developed for all‐organic photopolymers to point out the distinctive aspects related to the use of photoinitiated polymerization in hybrid sol–gel materials. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 831–840, 2003