阳离子树脂催化合成萜烯——邻苯二酚的研究

本文以强酸型阳离子交换树脂为催化剂 ,松节油和邻苯二酚为原料 ,合成了萜烯—邻苯二酚 ,对产物进行了红外、紫外光谱分析以及分子量测定 ,探讨邻苯二酚与萜烯的反应机理 ,并考察了反应条件对实验结果的影响。结果表明 ,在强酸型阳离子交换树脂催化下 ,邻苯二酚与萜烯发生烷基化反应生成萜烯—邻苯二酚 ,催化剂易于与产物分离 ,可重复使用 ;本实验中的较佳反应条件为 :松节油 邻苯二酚的摩尔比为 3∶1 ,催化剂用量为原料的 1 0 % ,温度为 1 2 0℃ ,反应时间为1 6h。     

PREPARATION AND CHARACTERIZATION OF SAWDUST/N-METHYLOLACRYLAMIDE/METHACRYLIC ACID CATION EXCHANGE COMPOSITES

Highly concentrated mixtures of methacrylic acid (MA) and N-methylolacrylamide (NMA) were polymerized in presence of purified sawdust using ammonium persulfate/sodium thiosulfate redox system in order to prepare sawdust/NMA/MA cation exchange composites. Polymerization was carried out under different conditions including the concentration of ammonium persulfate and sodium thiosulfate, temperature, liquor-to-sawdust ratio (LR) as well as concentration of both NMA and MA. Reaction conditions were optimized to prepare three cation exchange composites having capacities of 805, 615, and 530 meq/100 g. Potentiometric titration indicated that these composites were weak base cation exchangers and their strength, pK _a, decreased by decreasing the capacity. Characterization involved also the durability test, water solubility, and water swellability.     

NEW CATION EXCHANGE RESINS BASED ON POLYVINYL ALCOHOL CONTAINING CARBOXYL GROUPS FOR THE REMOVAL OF SOME TEXTILE CONTAMINANTS FROM AQUEOUS SOLUTIONS

Two cation exchange resins having carboxyl contents, 628 and 424 meq/100 g sample were prepared by free radical polymerization of acrylic acid in presence of polyvinyl alcohol aqueous solution using methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The prepared resins were characterized by investigation of their potentiometric titration, durability, water solubility, and swellability. The removal of Cu²⁺ ions (in the form of copper sulfate) from aqueous solution using these resins was studied under different conditions, including resin particle size, copper sulfate concentration, time, pH, liquor to resin ratio (LR), agitation speed, and resin capacity. A comparison was also held among the removal of other cations, namely Ni²⁺ and Co²⁺, in their sulfate forms. The resins were also utilized in the removal of some basic dyes from their aqueous solutions.     

阳离子交换树脂吸附焦化废水中氨氮影响因素研究

采用大孔H-103阳离子交换树脂分别对配制氨氮水溶液和焦化废水进行了动态吸附试验.结果表明,在优化流量条件下,树脂对氨氮水溶液和焦化废水中氨氮的饱和吸附量分别为66.86和12.5 mg·g-1;在吸附焦化废水中氨氮的同时,树脂对焦化废水中COD、SS、钙镁离子总硬度的去除率分别为20％、27％、70％,说明焦化废水中的部分有机物、悬浮物,特别是钙、镁离子,对树脂吸附氨氮产生了较强的竞争作用,使树脂对氨氮的最大饱和吸附量降低.对吸附处理前后焦化废水的气相色谱-质谱联用分析结果表明,可能与树脂吸附氨氮产生竞争吸附的有机物主要有苯酚及其衍生物、苯胺、喹啉、吲哚和萘等.     

CONFINEMENT EFFECTS ON ADSORPTION AND DIFFUSION OF HEXANE IN NANOPOROUS MCM-41 WITH DIFFERENT PORE SIZES: A MOLECULAR DYNAMICS STUDY

We report the results of molecular dynamics (MD) simulations using a new semi-empirical intermolecular interaction potential on the adsorption and diffusion of hexane in siliceous MCM-41 at 300 K. The potential function is tuned to give an adsorption energy of ? 9.1 kcal/mol, reproducing the experimental value for a corresponding pore size. We investigated MCM-41 models with four different pore sizes and studied loadings from one molecule of hexane up to a loading corresponding to the density of liquid hexane. As a result of confinement in MCM-41, the free energy of adsorption of hexane increases when the pore sizes decrease; for example, the adsorption energy increases from ? 9.1 to 13.7 kcal/mol for the largest to the smallest pore size for a loading of one molecule. Also, the adsorption energy increases by 3–4 kcal/mol for all pore sizes when the loading is increased from one hexane molecule to the density of liquid hexane. The calculated self-diffusion coefficients of hexane in MCM-41 with a pore diameter of 27 Å are in the order of 1 × 10^?5 cm²/s, depending on the loading, which is in reasonable agreement with available experimental data. The self-diffusion coefficients decrease with increasing loadings and when the pore sizes decrease. The average distance between the centers of the mass of hexane molecules in the smallest pores is only marginally less than in the larger pores and in the liquid phase. For low loadings the hexane molecules lie parallel to the pore channel for every pore size. When the loading is increased, they build up concentric rings. These rings of hexane molecules are less well separated from each other in the larger models, and thus their structure more resembles the liquid phase.     

ADSORPTION AND DESORPTION DYNAMICS OF SULPHUR DIOXIDE ON A SINGLE LARGE ACTIVATED CARBON PARTICLE

A single particle sorption model based on dual diffusion processes (pore diffusion and diffusion of adsorbed species) with equilibrium (Freundlich isotherm) between the macropore fluid phase and the sorbed phase was developed. The model was fitted to experimentally determined adsorption and desorption of SO₂ on large (0.2 cm radius) activated carbon particles over a range of temperatures and SO₂ concentrations. The model fitted the experimental data well and typical extracted values of the macropore and surface diffusivities were D_P = 0.038 cm²/s and D_s = 1.0 × 10^-5cm²/s at 25°C. The value of macropore diffusivity gave a macropore tortuosity factor of 8.0, whilst the temperature dependence of the surface diffusivity gave an activation energy of 5.0 kJ/mole.     

联苯夹套传热效果研究

对化纤生产中最常用的载热体——联苯混合物的传热效果进行了研究。根据对流传热速率方程及傅立叶定律导出了联苯的对流传热系数α的计算式。并结合生产实际情况,对不同类型的传热装置及联苯在失套中的不同充满情况作了一定的实验研究,求出了各种情况下联苯的对流传热系数a值。并通过比较得出套管换热器应以充满载热体,竖立安装为最佳。     

常减压换热网络的优化节能研究

应用自行开发的换热网络软件包,对吉化炼油厂常减压装置的换热网络进行了优化节能研究,通过换热网络的合成、分析、换热器优化设计及流程模拟,找出了原有换热网络存在的问题,提出了对原有换热网络优化改进的方案,并进行了优化设计。     

EFFECTS OF SOLUTE ADSORPTION ON HINDERED DIFFUSION UPTAKE RATES IN FINITE BATH EXPERIMENTS

This work investigates the effects of solute adsorption on hindered diffusion behavior in porous catalysts. A mathematical model describing the adsorptive diffusion process is developed. The model, termed the shrinking pore model, incorporates the local reduction in catalyst pore diameter due to the adsorption of solute molecules on the pore walls. The influence of the adsorbed solute layer is found to depend on two additional parameters, reflecting the relative degree of adsorption and molecule/pore size ratio. Hindered diffusion experiments are performed for diffusion controlled adsorptive uptakes of two solute molecules, quinoline and polystyrene, from cyclohexane on a porous catalyst. Comparison of the experimental data and model simulation results shows that for the larger polystyrene solute the shrinking pore model better represents the uptake behavior than the conventional model which assumes constant catalyst properties, e.g. pore diameter, during the uptake process. Experimental measurements were found to be in good agreement with model simulations after accounting for additional hindered diffusional effects due to an adsorbed solute layer on the pore walls. The additional hindrance due to the adsorbed solute was found to be very significant for the uptake of the larger polystyrene solute, whereas it was not significant for the smaller quinoline solute.     

REMOVING SOME HAZARDOUS HEAVY METAL ANIONS BY USING A NEW ANION EXCHANGER

Cross-linked sawdust bearing tertiary amine functional groups having an average capacity of 88 mEq/100 g and a strength pK_b of 10 have been found to be very efficient in removing some hazardous heavy metal anions (i.e., dichromate and permanganate) from their aqueous salt solutions. It was found that for a given set of treatment conditions, the lower the pH, the smaller the exchanger particle size range, the higher the agitation speed, and the lower the material-to-liquor ratio, the greater is the rate and extent of removal of dichromate anions from the surrounding medium. On the other hand, the effective exchange capacity as well as the affinity for hazardous anions are affected by contact time, pollutant concentration as well as type of heavy metal anion, and the percent removal followed the descending order: MnO₄ ^? > Cr₂O₇ ^2?.     

新型螯合纤维对重金属离子吸附性能的研究

本文研究了由聚(N-乙烯基甲酰胺／丙烯腈)水解得到的一种新型螫合纤维的合成、结构特征和螯合性能。这种纤维包含了高密度的螯合基像脒基、氰基和酰胺基等。研究结果显示了该纤维对金属离子有很高的束缚能力，对Cu^2 ，Cr^3 ，CO^2 和Ni^2 的最大吸附量分别为108．46，87．03，137．68和105．06mg／g。吸附在螫合纤维上的金属离子经洗脱后可回收，螯合纤维可以反复使用。     

溶液中菁染料的状态对其在AgBr表面吸附效应的量热研究

用半导体精密量热计测得25±0.01℃时溴化银从DMF-H_2O溶液中吸附噻碳菁染料(Ⅰ)的吸附热。发现由于溶液中染料聚集状态的不同导致吸附热明显不同,但吸附于溴化银表面的染料的聚集态则基本相     

花生壳吸附溶液中铀的研究

以废弃物花生壳为吸附剂来吸附水溶液中的铀,研究了花生壳加入量、溶液pH、铀初始质量浓度以及吸附时间等因素对铀吸附效果的影响。结果表明,花生壳对铀具有较好的吸附效果,当pH=4.0、花生壳用量为4 g.L-1、粒径为0.15～0.3 mm、铀初始质量浓度为30 mg.L-1、吸附时间为2.0 h时,铀的去除率达到了97.8%。等温吸附研究表明,花生壳对铀的吸附行为更符合Langmuir等温吸附方程,说明花生壳对铀的吸附是以单分子层吸附(化学吸附)为主,通过拟合得出最大吸附量为5.05 mg.g-1。     

吸附法回收废水中柠檬酸的传质机理研究

用静态实验筛选出的大孔吸附树脂ＡＢ－８在固定床内对吸附法回收柠檬酸的动态过程进行了研究。通过对包含轴向扩散的动力学模型的计算求得总传质系数，并结合由经验式得出的淮膜传质系地出该传质过程属内扩散控制，并通过实验得到验证。     

A NOTE ON THE MINIMUM NUMBER OF UNITS FOR HEAT EXCHANGER NETWORK SYNTHESIS

Although graph theory shows that the minimum number of exchangers (U_min) in a network is usually one less than the number of streams (N - 1), examples have been published, which demonstrate that this limiting case cannot always be achieved. Some of these examples contain a pinch point, for which it is advocated that the ‘N - 1 target’ should be applied on both sides of the pinch.

However, by using a novel arrangement of stream splitting, mixing and by-passes, some of the literature examples can be designed to conform to the N - 1 target.

For networks with similar total areas, those having fewer units will usually be cheaper, so U_min networks often have lower capital costs. Although the networks discussed here have somewhat larger total areas, possible applications are discussed where they may be economically attractive.     

A COMPARISON OF GAS SEPARATION PERFORMANCE BY DIFFERENT PRESSURE SWING ADSORPTION CYCLES

By simulations using an equilibrium model, a quantative comparison is made for different pressure swing adsorption (PSA) processes for gas separation. The comparison is based on the performance curve, which is defined as the relationship between product purity and product recovery at a fixed feed throughput.

For bed repressurization in the PSA cycle, the use of the light product yields superior separations compared to that using the feed mixture. For the pressure reduction step, it is found that the separation results are better when the heavy-product purge step is used, as compared to that using cocurrent depressurization. For an ultrahigh-purity light product, however, the PSA process using cocurrent depressurization is superior.

A new PSA process is suggested in which the heavy-product purge step is accomplished by using (or pressure-equalizing with) the effluent from another bed which undergoes the countercurrent blowdown step.     

膨胀石墨对有机化合物的吸附

研究了在水溶液中膨胀石墨对部分极性有机化合物的吸附特性，研究了有机物的极性、粘度、分子尺寸，溶解度、浓度和吸附剂比表面积等因素对吸附量的影响。     

电导法和互扩散法测定不等价反离子通过离子交换膜的扩散系数

本文从理论上分析了互扩散法和电导法测定反离子通过离子交换膜的自扩散系数，用这二种方法测定了Ｃｕ＾２＋和Ｈ＾＋通过聚苯醚均相阳膜的自扩散系数，对所得的结果进行了比较和验证。     

多级介孔炭对刚果红染料吸附性能的研究

以商业硅胶为模板,采用硬模板法制备了多级介孔炭,并研究了其对水溶液中刚果红染料的吸附性能.研究结果表明制备的多级介孔炭具有高比表面,大孔容和集中孔径分布以及高效吸附脱除刚果红染料的性能.多级介孔炭对水溶液中刚果红的吸附等温线符合Langmuir吸附模型,且在45℃具有最大吸附量,为446.89mg·g-1.吸附动力学研究表明动力学数据遵循拟二级动力学模型.热力学研究发现,在25～45℃内,刚果红在多级介孔炭上的吸附行为时吸热过程,且是自发进行的.     

无机-有机柱撑膨润土对水中苯胺的吸附行为研究

在OH^-和Al^3 的摩尔比为2．4的反应条件下。利用Al^3 与碱液反应制备出Keggin离子。并由此制备出了无机、无机-有机柱撑膨润土。XRD衍射数据表明：经柱撑后的膨润土层间距明显增大。达1．9nm以上。研究了苯胺在4种改性膨润土上的吸附行为。结果表明：经柱撑处理后的膨润土吸附能力明显大于钠基土。其吸附动力学行为遵循Bangham方程和Langmuir方程所描述的规律,平衡吸附量q,与平衡质量浓度pc之间的关系符合Freundlich和Langmuir等温吸附方程。吸附表现为放热的物理吸附和有机质的分配作用。