大孔树脂对甘油的静态吸附及其热力学研究

研究了8种大孔树脂对甘油的静态吸附行为,根据吸附等温线研究了吸附热力学性质,在303~323 K和研究的浓度范围内,树脂HPD500对甘油的吸附平衡数据符合Freundlich吸附等温方程。实验结果表明,较大的比表面积和带有一定极性的树脂有利于吸附,吸附过程为放热的物理吸附,降低温度有利于吸附。并计算了甘油在大孔树脂HPD500上的吸附焓变、吉布斯自由能变、吸附熵变,并对吸附行为做了合理的解释。     

Adsorption Kinetics and Equilibria of Strontium onto Kaolinite

Adsorption of Sr²⁺ onto kaolinite has been studied by means of a radiotracer technique using the ⁹⁰Sr isotope. Bangham’s and McKay models have been applied to kinetic results in Sr²⁺ concentrations between trace ?0.1 mol.L^?1. The magnitudes of film and intra-particle diffusion coefficients are 10?10 and 10?14 m²·s^?1, respectively. Concentration dependence of diffusion coefficients indicated that Sr²⁺ ions are adsorbed on two different adsorption sites by an exothermic and spontaneous process. The Freundlich isotherm parameters and exchange equilibrium constants derived from selectivity coefficients indicate that Sr adsorption are depressed by competing cations in the order of Na⁺< Mg²⁺< Al³⁺.     

大孔树脂对喹乐霉素的静态吸附

考察了9种不同极性的大孔树脂对喹乐霉素的静态吸附解吸效果,探讨了吸附过程中树脂静态吸附动力学和25℃时的等温吸附过程,并用Langmuir与Freundlich方程分别对吸附过程进行了拟合。结果表明,XAD-16和D101树脂对喹乐霉素的吸附解吸效果较好,比较两种树脂等温吸附的Langmuir和Freundlich参数,D101树脂对喹乐霉素的吸附解吸作用最好,吸附量最大,达到0.976 mg/g干树脂,吸附过程更易发生。因此,D101树脂更适用于从标桩菌WXNXJ-B发酵液中吸附并解吸喹乐霉素。     

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.     

红霉素在大孔树脂上的吸附动力学研究

采用液膜及孔内扩散模型,模拟不同温度和不同红霉素(EM)初始浓度条件下,大孔吸附树脂HZ816及XAD16吸附红霉素的动态吸附曲线,并获得液膜传质及孔内扩散系数;考察了温度及溶质浓度对红霉素在两种树脂中吸附动力学的影响.结果表明,在实验范围内,红霉素在HZ816和XAD16两种树脂上的吸附平衡数据满足Langmuir吸附等温线方程,液膜及孔内扩散模型能较好地描述红霉素在两种树脂上的吸附动力学,同时,模型拟合得到的液膜传质系数随着温度的升高而增大,随着初始浓度的增大而增大,孔内扩散系数随着温度的升高而增大,随着初始浓度的增大而减小.     

聚醚型螯合树脂的合成及其等温吸附性能

通过接枝反应制备了一系列以聚环氧氯丙烷为主链,侧链末端含吡咯配位基的HPnCP(n=6,4,2)螯合树脂,各步产物的化学结构经IR和1H NMR检测得以确认。静态吸附实验及等温吸附实验结果表明:该类树脂对Cu(Ⅱ)和Hg(Ⅱ)有着较好的吸附性能(大于1.0mmol/g);对Co(Ⅱ)和Cd(Ⅱ)达到饱和吸附时的平衡浓度约为0.06～0.07mol/l;HP_4CP对Co(Ⅱ)和Cd(Ⅱ)以及HP_2CP对Co(Ⅱ)的等温吸附既可用Langmuir方程描述也可用Freundlich方程描述;但HP_2CP对Cd(Ⅱ)的等温吸附不符合Langmuir方程,只可用Freundlich方程描述。     

大孔树脂复配纯化油茶多酚的吸附特性研究

为提高大孔吸附树脂对油茶多酚的吸附性能,采用不同极性的大孔树脂复配的方法,对油茶籽饼粕中提取的多酚物质进行吸附纯化。研究表明,90%(wt)D101-1/10%(wt)DM301复配对油茶多酚的吸附效率最高、达83.75%,且高于单一树脂对油茶多酚的吸附。在温度为298~315 K,三种模型的非线性拟合结果表明复配树脂对油茶多酚吸附平衡数据符合Langmuir等温吸附模型;对吸附焓、自由能、吸附熵的计算进一步验证了复配树脂对油茶多酚的吸附是放热自发的物理吸附。在此基础上进一步研究了298 K下复配树脂对油茶多酚的吸附动力学,结果表明Pseudo-second-order动力学模型能够很好地描述该吸附过程。     

汽车摩擦材料用酚醛树脂的研究概况

本文简要介绍了汽车摩擦材料用酚醛树脂的发展概况及目前国内外的研究动向。     

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.     

Adsorption Equilibrium and Kinetics of Toxic Dye-Erythrosine B Adsorption onto Montmorillonite

Erythrosine B is extensively used in the textile and food industry. It is reported to be a neurotoxicant and is carcinogenic in nature. It can induce DNA damage in the gastrointestinal organs even at low doses. In this study, adsorption efficiency of montmorillonite (MMT) has been investigated for the removal of erythrosine B (EB) from aqueous solution. The batch adsorption model was developed to predict the equilibrium adsorption capacity with respect to the pH of the dye solution, contact time, initial dye concentration, and adsorbent dosage. A maximum monolayer adsorption capacity of 578.03 mg/g was obtained at the original pH (7.5) of the aqueous dye solution within 5 minutes of contact time. It was found that the Langmuir adsorption isotherm yielded the most favorable representation of the adsorption behavior of EB. The dye was found to be chemisorbed on the adsorbent as confirmed by the FTIR spectral analysis. Although anionic in nature, the dye was found to be intercalated into the clay interlayers as suggested by the X-ray diffraction studies.     

Adsorption of Cu(II) and Cr(VI) onto Treated Shorea dasyphylla Bark: Isotherm,Kinetics, and Thermodynamic Studies

The efficacy of treated Shorea dasyphylla bark for Cu(II) and Cr(VI) adsorption was assessed in a batch adsorption system as a function of pH, agitation period, and initial metal concentration. The equilibrium nature of Cu(II) and Cr(VI) adsorption was described by the Freundlich, Langmuir, and Dubinin-Radushkevich isotherms. The maximum monolayer capacities of treated Shorea dasyphylla bark, estimated from the Langmuir equation were 184.66 and 42.72 mg/g for Cu(II) and Cr(VI), respectively. The experimental results were fitted using pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models; the pseudo-second order showed the best conformity to the kinetic data. Thermodynamic parameters such as enthalpy change (ΔH°), free energy change (ΔG°) and entropy change (ΔS°) were determined by applying the Van't Hoff equation. The adsorption of Cu(II) and Cr(VI) onto treated Shorea dasyphylla bark was found to be spontaneous and exothermic. The adsorption mechanism was confirmed by means of Fourier transform infrared (FTIR) and Energy dispersive X-ray (EDX) spectroscopy. The dimensionless constant separation factor (R _L), indicated that treated Shorea dasyphylla bark was favorable for Cu(II) and Cr(VI) adsorption.     

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.     

NTS在大孔吸附树脂上的吸附动力学及机理

在298 K时,采用静态法研究了H1020大孔吸附树脂对染料中间体对硝基甲苯邻磺酸(NTS)在水溶液中的吸附动力学,发现低pH值条件下有利于吸附进行,拟二级吸附动力学可很好地描述此吸附过程,膜扩散为此吸附体系控制步骤,并通过菲克定律计算出扩散系数D=0.64×10-9cm2/s.     

Comparison of Cr(VI) Adsorption Using Synthetic Schwertmannite Obtained by Fe3+ Hydrolysis and Fe2+ Oxidation: Kinetics,Isotherms and Adsorption Mechanism

Good sorption properties and simple synthesis route make schwertmannite an increasingly popular adsorbent. In this work, the adsorption properties of synthetic schwertmannite towards Cr(VI) were investigated. This study aimed to compare the properties and sorption performance of adsorbents obtained by two methods: Fe³⁺ hydrolysis (SCH_A) and Fe²⁺ oxidation (SCH_B). To characterise the sorbents before and after Cr(VI) adsorption, specific surface area, particle size distribution, density, and zeta potential were determined. Additionally, optical micrographs, SEM, and FTIR analyses were performed. Adsorption experiments were performed in varying process conditions: pH, adsorbent dosage, contact time, and initial concentration. Adsorption isotherms were fitted by Freundlich, Langmuir, and Temkin models. Pseudo-first-order, pseudo-second-order, intraparticle diffusion, and liquid film diffusion models were used to fit the kinetics data. Linear regression was used to estimate the parameters of isotherm and kinetic models. The maximum adsorption capacity resulting from the fitted Langmuir isotherm is 42.97 and 17.54 mg·g⁻¹ for SCH_A and SCH_B. Results show that the adsorption kinetics follows the pseudo-second-order kinetic model. Both iron-based adsorbents are suitable for removing Cr(VI) ions from aqueous solutions. Characterisation of the adsorbents after adsorption suggests that Cr(VI) adsorption can be mainly attributed to ion exchange with SO₄²⁻ groups.     

5种大孔吸附树脂对沙棘叶黄酮苷元的静态吸附/解吸附性能

以槲皮素、山奈酚和异鼠李素的静态吸附率/解吸附率为评价指标,考察了HPD600、YWD01G3、YWD01F、07C、AB-8 5种大孔吸附树脂对沙棘叶黄酮苷元的吸附/解吸附性能。实验结果表明:非极性树脂YWD01G3在吸附/解吸附方面显示出最佳的综合性能,对槲皮素、山奈酚、异鼠李素的平均吸附率和解吸附率分别为90.81%和59.51%。该实验为初步确定沙棘叶黄酮纯化用大孔树脂和进一步研究其动态吸附/解吸附提供了依据。该工作经中国科学院兰州查新咨询中心2006年3月28日出具的第2006033101号《科技查新报告》证实,未见相同文献报道。     

Enrichment and Purification of Total Chlorogenic Acids from Tobacco Waste Extract with Macroporous Resins

In the present study, an evaluation was conducted on the performance and separation characteristics of nine macroporous resins for the enrichment and purification of total chlorogenic acids from tobacco (Nicotiana tobaccum L.) waste extracts. Based on the results, XAD-4 offered higher adsorption and desorption capacities for total chlorogenic acids than other resins. To optimize the separation process of total chlorogenic acids, a column packed with XAD-4 resin was used to perform dynamic adsorption and desorption tests. The results show that the highest purity of the total chlorogenic acids product was 89.27% when optimum parameters for the adsorption process packed with the XAD-4 resin were as follows: flow rate 3.6 BV/h, pH 3.0; for desorption: ethanol–water (40:60, v/v) used as eluent, flow rate 3.6 BV/h, respectively. Therefore, the XAD-4 resin revealed a good ability to enrich and purify total chlorogenic acids. The method developed will provide a potential approach for the large-scale separation and purification of chlorogenic acid in pharmaceutical applications as a medical intermediate or a material for traditional Chinese medicine.     

Adsorption of bark derived polyphenols onto functionalized nanocellulose: Equilibrium modeling and kinetics

This article describes the kinetics and capacity of adsorbing condensed conifer tannins onto cationic cellulose nanocrystals (CCNCs). Batch adsorption experiments were carried as a function of pH, contact time, and initial tannin concentration with constant cationic cellulose nanocrystal concentration (0.01%). The adsorption process was highly pH dependent as adsorption capacities ranged from 13.2 mg/g to 112.7 mg/g at pH of 3–10. The amount of tannin adsorbed per unit mass of the cationic cellulose nanocrystals increased with increasing of tannin concentration until equilibrium was attained. The experimental data followed the Langmuir adsorption model, and the maximum experimental and theoretical adsorption capacities for the cationic nanocrystals reached 1,008 mg/g and 1,111 mg/g, respectively. The kinetics of adsorption was described best by the pseudo-second-order kinetics indicating a chemisorption process. The inherent adsorption has interesting applications for CCNC-complexes with natural polyphenolics in green chemical applications for adhesives, adsorbents, preservatives, and packaging materials.     

Kinetic and Equilibrium Study for the Fluoride Adsorption using Pyrophyllite

Batch adsorption study was carried out to remove excess fluoride from water using pyrophyllite. Result showed that adsorption of fluoride was rapid in first 20 min and thereafter increased slowly to reach the equilibrium in about 2 hrs. About 85% removal efficiency was obtained within 2 hrs at an adsorbent dose of 4 g/L for initial fluoride concentration of 10 mg/L. Maximum fluoride adsorption takes place at pH 4.9. Thermodynamic parameters such as Gibb's free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) changes were determined for the adsorption process. Negative ΔH° value signified that the adsorption process was exothermic in nature. From the kinetic study it was found that fluoride adsorption by pyrophyllite followed pseudo-second-order kinetics with an average rate constant of 0.92 g/mg · min. Intraparticle diffusion model was studied to determine the rate limiting step of the adsorption process. The system followed the Langmuir isotherm with maximum adsorption capacity of 2.2 mg/g of fluoride.     

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.     

我国塑料加工企业现状及相关树脂市场分析

通过对天津地区塑料加工企业的调研,阐述了目前塑料加工企业的现状及其对石化树脂产品－聚乙烯,聚丙烯,聚氯乙烯的需求状况,进而分析了石化树脂产品在国内市场销售中存在的问题及今后改进方向。