Complexation and Adsorption Studies of 27-Membered Dioxadiazapentathia Macrocycles with Some Transition Metals

The metal ion-binding properties of two 27-membered macrocycles with N₂S₅O₂ donor atoms 1 and 2 were investigated using solvent extraction experiments. In order to explain complexation behavior of macrocycles, extraction of ions in the interfacial region of liquid-liquid phase was modeled by Langmuir adsorption isotherm. The macrocycles 1 and 2 extracted Ag⁺ metal ion up to 95% to the dichloromethane and chloroform phase effectively. The Ag⁺ ion adsorption capacities of macrocycles 1 and 2 were obtained as 75% and 98% at 20°C, respectively.     

Untersuchung verbesserter Methoden zur Vermeidung von Entrainment in Rektifikationskolonnen

Unwanted entrainment of droplets to succeeding process areas is one of the main challenges for efficient operation of separation processes like rectification or evaporation. Fluctuation in temperatures, pressures or flow rates lead to operating conditions that cause entrainment. This results in significant losses both in means of energy and costs. Therefore, new approaches to reduce entrainment were investigated in a joint project with focus on rectification processes.     

An Additional Insight into the Correlation between the Distribution Ratios and the Aqueous Acidity of the TODGA System

Abstract

Extraction of Eu(III) and Am(III) from HNO₃ into the organic solvents using N,N,N′,N′‐tetraoctyl‐diglycolamide (TODGA) was investigated in order to study the detailed extraction reaction. The chemical species: 1:2 for metal:TODGA complex is present in polar diluents. On the other hand, the metal complexes need three or more TODGA molecules to remain stable in non‐polar diluents. The HNO₃ concentration dependence on the distribution ratio suggests that HNO₃ participates in the metal extraction. Infrared spectra indicate that the carbonyl oxygen coordinates with Eu(III), and luminescence lifetimes suggest that there are no water molecules in the inner coordination sphere of the extracted Eu‐complex.     

Entrainment behaviour of high-density Geldart A powders with different shapes

Atomised and milled Ferrosilicon with average particle diameters of 38 and 50 µm respectively were fluidised with air at ambient conditions. The entrainment rate of the more spherical atomised particles was on average six times that of the irregularly shaped milled particles over the range of superficial velocities investigated. In an attempt to decouple the effect of particle size from shape, the bed was divided into theoretically isolated bins based on the distributions of particle sizes. This indicated that the atomised particles had a higher entrainment rate for particles smaller than approximately 25 µm whereas the opposite was true for particles greater than this size. None of the entrainment correlations investigated was able to predict the switch in entrainment behaviour as a function of particle sphericity and diameter. Furthermore, the traditional critical particle diameter associated with cohesive Geldart A particles was not observed for either of the two particle shapes. It is therefore concluded that neither the hydrodynamic nor Van der Waals forces acting on the particles can adequately explain the entrainment rate behaviour of differently shaped high-density Geldart A particles.     

圆形射流夹带量的分析与数值模拟

分析了圆形喷嘴形成的射流夹带流的特性,建立了柱坐标系及控制体,并利用流体的连续性方程给出了夹带流流量的公式,而且将计算结果与前人的试验结果进行数值模拟和比较验证。     

Quantification of Entrainment Using an Optical Inline Probe

In distillation and absorption processes, entrainment above trays or packings reduces stage and column efficiency. A modified version of the optical multimode online probe enables a seminal insight and, thus, quantification of entrained droplets on various axial and radial positions. A purging mechanism inhibits precipitation of droplets on the front lenses, while telecentric optics and illumination provide distance‐independent and precise imaging of entrained droplets between two valve trays. Experiments were performed in a DN 450 cold flow (air‐water) test rig. The results were compared with noninvasive phase Doppler anemometry data.     

射流混合中夹带流速度的分析与数值模拟

分析了圆形喷嘴形成的射流夹带流的特性,建立了柱坐标系及控制体,并利用流体的连续性方程给出了夹带流沿母线的速度公式,应用Excel进行了模拟,而且应用前人的实验结果进行了验证。     

Droplet Entrainment Analysis in a Flash Evaporator with an Image-Based Measurement Technique

Local droplet sizes and volumes of entrained liquid are captured with an image-based measurement technique for comparison with a conventional, integral method for entrainment analysis. Experiments in a forced circulation flash evaporation were performed for different operating conditions and with two different chemical systems. Droplet size and frequency rise with an increase in thermal energy input. The local readings confirm the trends found by the integral measurement method. The modification of the image-based probe enables the detection of small (≈ 10 µm) and at the same time fast droplets under challenging operating conditions, such as vacuum and superheated feed similar to industrial process conditions.     

闭式涡轮搅拌萃取塔液滴直径的估算

本文利用均匀各向同性湍流特性分析连续相湍流脉动液滴大小的影响，得出搅拌强度和液滴平均直径之间的关系，根据所使用的三种塔几何结构所得的实验数据检验。理论分析结果与实验所得结果较好地相符。本文也讨论了分散相存留分数对平均液滴直径的影响。     

乙酰甲胺磷萃取工艺

研究了不同溶剂对废水中乙酰甲胺磷的分配系数,采用二氯甲烷、三氯甲烷分段萃取的工艺可有效降低生产成本,采用转盘萃取塔可使废水中乙酰甲胺磷的含量降到1％以下。     

The Influence of the Hofmeister Bias and the Stability and Speciation of Chloridolanthanates on Their Extraction from Chloride Media

The possibility of recovering rare earth elements from solutions containing their chloridometalate anions [LnCl_x]^(x?3)? via the process: LnCl_x^(x?3)? + (x ? 3)L_org + (x–3)H⁺ ? [(LH)_x?3LnCl_x]_org has been tested using 2-(1,3-bis(hexylamino)-1,3-dioxopropan-2-yl)-4,6-di-tert-butylpyridine (PMA), tri-n-butylphosphate (TBP), and tri-n-octylamine (TOA), which are known to be strong extractants for transition metal chloridometalates. While DFT calculations indicate that the formation of the neutral assembly [(PMAH)₃LaCl₆] in the gas phase is favorable, no uptake of La(III) from 6 M HCl by toluene solutions of PMA (or of TBP or TOA) was observed in solvent extraction experiments. Successful uptake of the [PtCl₆]^2? dianion by PMA and the failure to extract the [IrCl₆]^3? trianion under the same conditions indicate that the higher hydration energy of the latter makes transfer to the toluene solution less favorable and that this militates against extraction of La(III) chlorido complexes carrying charges of ?3 or larger in which all the inner-sphere water molecules have been replaced. Computational results confirm literature observations that, in contrast to transition metal trications, formation of REE metalate anions such as [LnCl_x]^(x?3)? is not very favorable, particularly so for chloride, compared with nitrato or sulfato systems. Also, they indicate that the formation of outer-sphere assemblies such as {[La(H₂O)₉]·xCl} in which water ligands are retained in the inner sphere, H-bonded to anions, is more stable than inner-sphere complexes containing an equivalent number of anions. The high level of hydration of such species disfavors their transfer into nonpolar water-immiscible solvents. It is unlikely that recovery of [LnCl_x]^(x?3)? from acidic solutions can be achieved efficiently using currently available anion exchange extractants operating in a “pH-swing” process. Receptors giving very high binding energies to chloridolanthanates will be needed to offset the high dehydration energies required.     

Application of GPC to Studies of the Viscose Process. II. The Effects of Steeping and Alkali-Crumb Aging

Abstract

Changes in the distribution of degree of polymerization (DP) of cellulose during the steeping and alkali-crumb aging steps of the viscose process have been studied. A dissolving-grade pulp was used, and two mechanisms of degradation—oxidation and hydrolysis—were considered. Alkaline hydrolysis was relatively unimportant during the steeping, the major change in the DP distribution being a result of the much faster oxida-tive degradation. The extent of oxidation was determined by the solubility of oxygen in the alkali solution. Both oxidation and hydrolysis cause degradation during the aging of alkali crumb. Under the conditions used, hydrolysis was a slow, pseudo-first-order reaction, and oxidation a much faster zero-order reaction. Since there was a large difference in the rates of these reactions, the kinetics of degradation approached zero order.     

分子蒸馏分离烟草提取物溶剂选择性萃取试验研究

对分子蒸馏分离烟草提取物的溶剂进行了研究。利用正交试验设计研究了影响溶剂萃取的各种因素 ,并确定了较合理的萃取条件。     

环丁砜降解对芳烃生产的影响及解决措施

分析了芳烃装置运行中环丁砜溶剂降解给生产带来的不利影响,通过采取一系列的技术措施将不利影响降至最低,保证芳烃装置的长周期、满负荷运行。     

往复式振动筛板塔净化湿法磷酸的研究

为了开发湿法磷酸(WPA)净化的新工艺及设备,根据溶剂萃取净化湿法磷酸的物性与振动筛板塔的特性,设计研制了振动筛板塔,并进行溶剂法净化湿法磷酸的设备结构参数与操作条件的实验,找出了萃取、洗涤、反萃3个主要过程的设备结构参数与适宜操作条件,萃取:筛板间距为7 cm,振动频率为200 r/min;洗涤:振动频率为100 r/min,相比(体积)为20∶1;反萃:筛板间距为6 cm,振动频率为250 r/min。经3塔串联连续实验,最终制得符合工业品级质量的磷酸,效果良好。成功开发了WPA净化的新工艺、新设备,为中试及工业化放大创造了有利条件。     

Solvent Effect on Complexation of Titanium Tetraethoxide with Allylacetoacetate

The effect of the solvent butanol on the complexation reaction of allylacetoacetate (AAA) with titanium tetraethoxide. (Ti(OEt)₄) in molar ratio Ti(OEt)₄:AAA = 1:1 was investigated by ¹³C-NMR, FT-IR spectroscopy and elemental analysis. The investigation shows that some ethoxy groups that are attached to the titanium are substituted with butoxy groups. The hydrolytic stability of the allylacetoacetate–Ti complex in a molar ratio Ti(OEt)₄:H₂O = 1:4 was also characterized by spectroscopic techniques and elemental analysis. The result of this characterization shows that almost 20% of the AAA and some ethoxy groups are released from the hydrolyzed product.     

间苯二酚的配合萃取研究

采用配合萃取法回收水溶液中的间苯二酚 ,研究了影响萃取效果的有关因素 ,确定了萃合物的组成 ,探讨了萃取的机理     

筛板雾沫夹带二维分布的研究

在直径1.2m的筛板试验塔上,以空气—水为介质,采用捕集称重法,对塔板雾沫夹带分布状况进行了测定;并用正交多项式回归方法,拟合得到二维雾沫夹带不均匀分布函数;文中运用二维定数混合池模型,计算并讨论了雾沫夹带分布对塔板效率的影响.     

Studies on Development on Methodology for Extraction of Phenolic Compound from Hydro-Alcoholic Wood Extracts

This article presents results on the liquid-liquid extraction studies for the separation of tannic acid from aqueous and hydro-alcoholic medium. These liquid-liquid extraction studies aim to investigate the suitable hydrophobic solvent or solvents combination and to optimize the extraction conditions for the quantitative separation of tannic acid from aqueous and hydro-alcoholic feed. A mixture of hexanol and octanol is found to be most suitable for the quantitative extraction of tannic acid from aqueous feed solution. One hour equilibration time was enough to reach equilibrium. With increase in tannic acid concentration from 10 mg · L^?1 to 900 mg · L^?1 in the feed solution, the extraction of tannic acid was found to be decreasing. The concentration of ethanol plays an important role in controlling the solubility of feed in hydrophobic solvent. The suitable solvent combination was tested for the selectivity for individual polyphenol from a mixture of tannic acid and Epi-catechin and it was found that a combination of hexanol and octanol was good for tannic acid extraction whereas decanol was more selective for Epi-catechin extraction.