三元溶剂对稀醋酸萃取性能的研究(一)

本文回顾了稀醋酸萃取剂的进展;测定了三种叔胺、三种醇和煤油组成不同的混合溶剂时,醋酸分配系数与溶剂组成的关系,发现胺和醇在溶剂中的含量在中间某个值时获得的醋酸分配系数最高;测定了N_(235)-癸醇-煤油三元溶剂萃取醋酸的等温分配关系。     

填料塔萃取回收醋酸废水的工艺研究

采用络合萃取方法处理工业中的低质量浓度醋酸废水,考察了三烷基胺与三正辛胺对醋酸废水的萃取效果,分析了三烷基胺、正辛醇和煤油体积分数、原料液初始质量浓度和pH对萃取效果的影响。利用填料萃取塔和反萃塔,观察混合萃取剂对醋酸废水的萃取效果。实验结果表明,在相同的体积分数下,三烷基胺萃取效果优于三正辛胺。在填料萃取塔中,使用混合萃取剂体积分数40%三烷基胺-30%正辛醇-30%煤油处理初始质量浓度为30 g/L醋酸水溶液,萃取效果较好,醋酸回收率可达95.25%。     

醋酸稀溶液的络合萃取

络合萃取法对于极性有机物稀溶液的分离具有高效性和高选择性。本文以醋酸稀溶液为分离对象,通过系统的相平衡实验筛选出30 wt％三辛胺(或7301)+20 wt％正辛醇+50 wt％煤油混合溶剂。同时,探讨了叔胺类萃取剂对醋酸萃取的过程机理,研究了混合溶剂萃取稀醋酸工艺的可行性。     

络合萃取技术在苯胺-硝基苯废水处理中的应用研究

选用20％三烷基胺-80％加氢煤油作为萃取剂，进行四级萃取实验，探讨络合萃取技术处理苯胺-硝基苯废水工业化的可能性。实验结果表明，采用三烷基胺-加氢煤油混合溶剂对苯胺-硝基苯废水进行萃取，具有相当高的COD脱除率。     

测定苯酚废水在几种不同萃取剂中的分配系数

本文研究支撑液膜处理含酚废水的基础数据——苯酚在萃取剂和水中的分配系数．以确定最佳的萃取剂。实验选择了TBP-煤油及松香胺-煤油两体系作为萃取剂，测定苯酚在其中的分配系数。结果表明，在实验范围内苯酚在两体系中的分配系数均随着载体含量的增加而增大，随着苯酚浓度的增大而增大，而温度的影响则非常有限。     

络合萃取法处理高浓度H酸废水

采用络合萃取法处理高浓度H酸废水,考察了萃取体系、萃取时间、萃取级数、萃取剂体积分数、相比(A/O)、油碱比对COD的去除效果的影响。最佳体系为:三辛胺为络合剂,煤油为稀释剂,正辛醇为助溶剂。以三辛胺/煤油/正辛醇体系进行萃取实验,得到最优工艺参数为:V(三辛胺)/V(煤油)=1/4,相比(A/O)=5/1,pH=2.3,萃取时间为30 min;当H酸初始COD为35 000 mg/L时,经两级错流萃取后COD去除率可达到83.4%。采用12.5%的Na OH溶液对萃取相进行反萃取,可回收并循环利用萃取剂。实验结果表明:络合萃取工艺处理H酸生产废水效果显著,达到了预处理的目的,有利于实现工业化生产。     

橡胶助剂生产废水中醋酸回收工艺研究

采用有机溶剂络合萃取法研究了生产橡胶助剂废水中醋酸的回收工艺过程。实验表明,三辛胺为该体系的最佳萃取剂,优化的醋酸回收工艺路线为:减压蒸出丙酮,再加入三辛胺络合萃取醋酸,萃取相减压蒸馏回收醋酸后循环使用,处理后废水可排放。通过响应面法得出单级萃取操作的最佳工艺条件:相比(V废水/V萃取剂)1.06∶1,萃取时间41m in,萃取温度20℃。三级萃取醋酸回收率98%,醋酸质量分数达92%,同时回收丙酮11/100(V丙酮/V废水)。     

溶胀对膜萃取传质性能的影响

溶剂对膜的溶胀,使膜的物理结构发生变化,进而对膜萃取传质性能产生一定的影响。本文以３０％ＴＢＰ（煤油）－醋酸－水,正丁醇－醋酸－水和２０％７３０１（煤油）－醋酸－水为实验体系在聚砜和聚四氟乙烯微孔平板膜器中系统地了溶胀地膜萃取总传质系数的影响。结果表明,微孔膜发生溶胀后孔隙率发生明显的变化,其总传质系数有较大的下降。     

湿法磷酸的净化脱氟新工艺研究

为对湿法磷酸进行净化脱氟,用胺类溶剂作萃取剂,煤油作稀释剂,对湿法磷酸进行了溶剂萃取脱氟的工艺研究,实验重点研究了萃取剂的浓度,酸化时酸的浓度及萃取温度对胶氟效率的影响,结果表明,若胺在萃取剂中浓度为15％,用50％－75％的硫酸酸化后,在40－60℃时萃取,有很好的脱氟效果。     

络合萃取法在2-萘酚废水处理中的应用研究

采用络合萃取法,以三烷基胺和磷酸三丁酯为萃取剂、煤油为稀释剂处理2-萘酚β-盐母液废水。试验结果表明：采用20％三烷基胺-20％磷酸三丁酯-60％煤油的混合型络合萃取剂对2．萘酚废水进行萃取具有较高的COD脱除率。     

Characterization of compositional heterogeneity in copolymers and coatings systems by GPC/FTIR

One of the long-sought ‘holy grails' of polymer characterization has been the simultaneous determination of polymer composition as a function of molecular weight distribution. The recent commercialization of a solvent evaporative interface between a Gel Permeation Chromatograph (GPC) and a Fourier Transform Infrared (FTIR) Spectrometer has provided one useful solution to the problem of determining polymer composition as a function of molecular weight for a range of polymers. This study will focus on the use of a solvent evaporative interface in conjunction with a GPC-viscometer chromatograph and a FTIR spectrometer in order to provide functional group information as a function of molecular weight. The solvent evaporative interface will be described and its use with a GPC-viscometer/FTIR system will be discussed in terms of operational variable and data analysis considerations. Application of the GPC-viscometer/solvent evaporative interface/FTIR system to a variety of polymer and coatings systems as a tool for product problem solving and elucidation will be presented. In addition, examples of the use of the solvent evaporative interface to elucidate compositional heterogeneity of copolymers will be illustrated. The potential use of the solvent evaporative interface in GPC/LC cross fractionation studies for very fine elucidation of polymer compositional heterogeneity will be discussed.     

Studies on comonomer compositional distribution and its effect on some physical properties of bacterial poly(3‐hydroxybutyric acid‐co‐3‐hydroxypropionic acid)

Comonomer compositional distribution of bacterially synthesized poly(3‐hydroxybutyric acid‐co‐3‐hydroxypropionic acid) [P(3HB‐co‐3HP)] was investigated via solvent/non‐solvent fractionation techniques. The result indicates the presence of extremely broad comonomer compositional distribution in the original bacterial product. Furthermore, utilizing compositionally fractionated bacterial copolyesters with much narrower comonomer compositional distributions, the 3HP comonomer content‐dependence of their thermal and crystallization behavior was studied by means of differential scanning calorimeter (DSC) and polarized optical microscopy and the results compared with those of unfractionated copolyesters. It was revealed that the physical features of the fractionated copolyester P(3HB‐co‐3HP)s strongly depends on the 3HP comonomer content. In addition, to clarify the effect of the compositional distribution on the properties of the unfractionated copolyester, the miscibility between bacterial poly(3‐hydroxybutyric acid) [P(3HB)] and two fractionated P(3HB‐co‐3HP) samples with 11.3 and 14.9% 3HP was investigated for blends obtained by solvent casting techniques. The evidence of thermal analysis and spherulitic growth rates imply miscibility of the P(3HB)/3HB‐rich P(3HB‐co‐3HP) binary blends. © 1999 Society of Chemical Industry     

Characterization of Three Types of Semtex (H, 1A,and 10)

Solid phase microextraction and solvent extraction were used with GC/MS to determine the vapor and compositional profile of three samples of Semtex (1A, H, and 10). Semtex is reported to contain PETN and/or RDX, along with plasticizers, binding materials, and fuel oil components. In an effort to differentiate and compare these three variations of Semtex, this report summarizes the headspace and solvent extraction results for each material. Components that can be used to differentiate varieties of Semtex were identified and all three Semtex profiles were distinguished.     

Compositional changes during the wet spinning of acrylic fibers from aqueous sodium thiocyanate solvent

The compositional changes taking place during the wet spinning of acrylic fibers from an aqueous sodium thiocyanate solvent were investigated. The composition of the fibers diverted from the precipitation bath after various immersion times was determined gravimetrically, while fiber diameters were imaged to ascertain volumetric changes with time. The kinetics of phase separation were approximated using light transmission and video techniques applied to acrylic films. For coagulation into water at 20 and 40°C and into 15% aqueous NaSCN at 20°C, a greater influx of the nonsolvent to outflow of the solvent was recorded at short timescales. Unexpectedly, both the outflow of the solvent and nonsolvent against the concentration gradient was noted at longer timescales, suggested by the light transmission data to be after the primary phase separation. The consequent reduction in filament diameter, hence, the volume, is discussed in terms of a coarsening mechanism, whereby the mobile polymer lean phase has a route away from the filament into the bath during polymer coarsening. Finally, the compositional changes are plotted on a phase diagram for the system as trajectories into the two-phase region. The polymer-coarsening effect renders the interpretation at longer timescales uncertain. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 69: 1459–1469, 1998     

Bench-scale continuous hydrogenation of Australian coals — study of iron catalysts and recycle solvent composition

The inter-relations between iron catalysts, recycle solvent composition and product yield and composition have been investigated in bench-scale (1–2 kg h^?1) continuous hydrogenation of Australian coals at process severity of 21–22 MPa at 400–430°C. Products and recycle solvent are recovered in batch distillation (atmospheric and vacuum) and the distillate solvent is returned to slurry feed without further treatment. Successive samples of recycle solvent are analysed by g.c.-m.s., i.r. and titrimetry. The effect of adding iron catalysts in the form of red mud - sulphur mixtures or compounds after a short period of continuous operation without catalyst is demonstrated. Distillate yields from black coals increase from 24–34 wt% daf under non-catalytic conditions to 35–53 wt% daf by adding iron catalysts. The composition of the almost equilibrated recycle solvent also changes and a new equilibrium is approached after the iron catalyst is added. The effect of solvent composition on distillate yield can not be determined from these data. The ratio of hydroaromatic components to hydroaromatic plus aromatic components in the solvent increases from ≈0.2 at non-catalytic equilibrium to ≈0.5–0.6 at catalysed equilibrium after adding iron. Other compositional parameters in the recycle solvent do not show any clear responses to the addition of iron. Equilibrium solvent composition under constant operating conditions is attained at ≈10 passes at 1 kg ^h?1 throughput with total system holdup of ≈20 kg. Paraffins for the Queensland subbituminous coal equilibrated at 18–24% in the solvent, phenolics at 16–21%, basic nitrogen at ≈0.4% (as N), and the balance a mixture of aromatics and hydroaromatics. The total aromatics neglecting phenolics in the equilibrium recycle solvent consists of ≈40–50% each of two-and three-ring and 5–10% four-ring members.     

Chemical evaluation of egyptian citrus seeds as potential sources of vegetable oils

Seeds of the citrus fruits orange, mandarin, lime and grapefruit were analyzed. Petroleum ether-extracted oils of such seeds amounted to more than 40% of each. Physical and chemical properties of the extracted oils are presented. Samples of the extracted oils were saponified and the unsaponifiables and fatty acid fractions isolated. The isolated unsaponifiables and fatty acids were analyzed by GLC. GLC analysis of the unsaponifiables revealed compositional patterns differ-ent in number, type and relative concentration of fractions according to type of citrus seed oil, depending on the solvent system used for oil extraction and unsaponifiable matter isolation. The compositional patterns of the unsaponifiables were similar to that of cottonseed oil. Mandarin and grapefruit oils are free of cholesterol. The data demonstrate that the fatty acid compositional patterns of the oils differ; Mandarin seed oil contains the largest number of fatty acids, and grapefruit seed oil contains the lowest. The total amounts of volatile fatty acids in these oils are generally higher than those of other edible oils. Lime seed oil is similar, in the degree of unsaturation, to soybean oil. The orange oil pattern is similar to cottonseed oil. The amount of total essential fatty acids in lime seed oil is the highest of the oils studied.     

Detailed compositional study of the Light Cycle Oil (LCO) solvent extraction products

The liquid-liquid extraction of the Light Cycle Oils (LCO) fraction was studied using acetonitrile and its mixtures with water and methanol at 40 °C and 1:1.5 solvent-to-feed ratio. The yield of raffinate was found to increase with increased water content in the solvent, while it was invariant in the presence of MeOH. Detailed compositional study of the LCO feed stock and its extraction products using FT-IR and GC-MS techniques, revealed characteristic distribution patterns of individual saturated and aromatic hydrocarbons in the raffinate and extract fractions. The developed analytical protocol provides detailed compositional information of the extraction products and can be used efficiently in future studies dealing with the upgrading of the LCO.     

Role of solute and solvent on the deposition of ZnO thin films

ZnO thin films have been deposited on SnO₂:F coated transparent conducting oxide (TCO) glass substrates, using a simple electrochemical (galvanic) technique, from different electrolytic solutions. A detailed investigation on the effect of different solute and solvent on the deposition process has been made. We have established that galvanically obtained ZnO thin films can be deposited with various morphologies depending on the nature of the solute and solvent used. ZnO formation can happen either directly or through an intermediate mixed phase following different reaction paths. Structural, morphological, compositional and optical characterizations of the films developed under different conditions were carried out to study such effects. The films were also tested for their potential use as methane sensor.     

Metal chelation and spatial profiling of components in crown ether functionalised conducting copolymer films

Crown ether functionalised conducting polymer films were used to complex barium ions from acetonitrile solution. It was found that fully-functionalised N-derivatized polypyrrole films do not possess adequate mechanical stability, but dilution with unfunctionalised bithiophene co-monomer leads to a series of copolymer films with excellent stability. Film reactivity, composition and structure were investigated using electrochemical, nanogravimetric, FTIR, XPS and neutron reflectivity techniques. The first three of these provided spatially integrated barium populations and neutron reflectivity provided spatially resolved compositional profiles. Measurements at various stages of film fabrication yielded spatial distributions of co-monomer, crown ether, solvent and barium (as perchlorate) components. Critically, the amount of free volume to accommodate crown motifs and barium within the film was limited by the film's internal microstructure and solvent content; the low solvent volume fraction creates a different local environment to solution.     

Preparation of Monodisperse ZrO2 by the Microwave Heating of Zirconyl Chloride Solutions

Based on the principle that the solubility of a salt decreases as the dielectric constant of the solvent decreases, zirconia powders were prepared by heating a zirconyl chloride solution with a 2-PrOH-water mixture as the solvent. The morphology, size, and size distribution of the resulting particles were highly sensitive to the heating method used on the starting solution. Particles formed under conventional heating methods were polydisperse, agglomerated spherical, or irregularly shaped because of inhomogeneous precipitation through the temperature gradient, the shear force induced by stirring, compositional nonuniformity, and the low heating rate. The present study demonstrated that microwaves provide an excellent means of heating uniformly and rapidly without stirring. The particles resulting from microwave treatment were monodisperse and spherical, with a mean diameter of 0.28 μm.