Efficient recovery of ionic liquid by electrodialysis in the acid hydrolysis process

Electrodialysis (ED) has been recently known as a highly effective technique to remove and recover ionic liquids from aqueous solution. When a conventional electrolyte solution for the ED process containing Na₂SO₄ was used, a recovery ratio of an acidic IL, 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim][HSO₄]), was 90%. On the other hand, the value clearly increased to 96% when we employed [Bmim][HSO₄] as the electrolyte solution. In an acid hydrolysis of bagasse using the IL under microwave irradiation, the recovery ratio maintains 96%, irrespective of reaction time. This demonstrates the applicability of the proposed ED system in biomass processing.     

共聚尼龙增韧改性聚甲醛的研究

本文采用共聚尼龙，用机械共混的方法对聚甲醛进行增韧改性，并对共混物的形态，结构与力学性能进行测试与分析。研究发现，在ＰＯＭ／ＣＯＰＡ共混体系中，存在着氢键的相互作用，且氢键的相对强度随ＣＯＰＡ含量的增加而增加。ＣＯＰＡ的加入，使得ＰＯＭ的熔融温度Ｔｍ和结晶温度Ｔｃ均增加，ＣＯＰＡ含量在１０％以下质量范围内，ＣＯＰＡ对ＰＯＭ具有增韧改性作用。     

Polyamide membrane precipitation studied by confocal backscattering microscopy

A wide variety of commercial polymeric membranes are manufactured by a non-solvent immersion precipitation process, yet the detailed mechanism and kinetics of membrane formation are poorly understood. We have used a confocal microscope, with fluorescence filters removed, to observe backscatter from precipitating nylon 6 films. Nylon 6 in formic acid/water solutions was spread on a glass substrate, which was then quickly immersed into water or water/formic acid non-solvent baths. Two slope-casting chambers were designed in order to observe the precipitation process from both the substrate side and the bath side (in separate experiments). From the substrate side, a scattering front was observed to form within a few seconds after immersion, and then to progress toward the substrate as the precipitated film formed. When observed from the bath side, the scattering front first moved toward the bath for approximately 5-10 s, then reversed direction and moved toward the substrate. This later motion toward the substrate can be explained by the contraction of the film as water is expelled. The initial motion toward the bath implies that the initial point of precipitation is not at the film surface, but rather at some depth (ca. 60+ μm) within the film. This new application of confocal microscopy has enabled measurements of the dynamics of nylon membrane precipitation with sufficient time and depth resolution to permit quantitative testing of models of the precipitation process.     

Furfural production by acid hydrolysis and supercritical carbon dioxide extraction from rice husk

The aim of this research was to study the effect of furfural production from rice husk by hydrolysis accompanying supercritical CO₂ (SC-CO₂) extraction. The two-level fractional factorial design method was used to investigate the production process carried out with respect to furfural yield. The process variables are temperature range of 373–453 K, pressure 9.1–18.2 MPa, CO₂ flow rate 8.3 × 10⁻⁵–1.7 × 10⁻⁴ kg/s (5–10 g/min), sulfuric acid concentration 1 to 7 (%wt) and ratio of liquid to solid (L/S) 5 : 1 to 15 : 1 (vol/wt). The results obtained from the experimental design showed that increasing temperature, pressure, CO₂ flow rate and sulfuric acid concentration but decreasing ratio of liquid to solid would improve furfural yield. Moreover, furfural production by two-stage process (pre-hydrolysis and dehydration) can improve furfural yield further to be around 90% of theoretical maximum.     

有机硅氧烷的水解-缩聚机理研究

用溶胶-凝胶法,按部分电荷模型研究了甲基三乙氧基硅烷和正硅酸乙酯的水解-缩聚机理,用富立叶红外光谱(FT IR)研究了水解-缩聚产物的结构。结果表明,TEO S的完全水解与缩合物具有石英玻璃结构;M TEO S由于S i-C键的稳定性,产物中包含-CH3基团。     

The enzymatic hydrolysis of triglyceride-phospholipid mixtures in an organic solvent

The abilities of four commercially available lipolytic enzymes [three immobilized lipases—Lipozyme IM-20, SP-435 (Novo Biolabs, Danbury, CT), and AY-30/Celite (Amano Enzyme Co., Ltd., Troy, VA)—and a nonimmobilized Amano phospholipase B preparation] to hydrolyze mixtures of triacylglycerols (TG) and phospholipids (PL) were determined. All of the lipases hydrolyzed both types of substrates in water, with maximum rates of TG hydrolysis exceeding those of PL hydrolysis by between 20- and 200-fold. The phospholipase B preparation was inactive against both TG and PL in water. All the enzymes showed some activity against lipids in hexane. The amount of activity was sharply dependent on the amount of water added to the reaction. Lipozyme IM-20 and AY-30/Celite hydrolyzed both TG and PL in hexane. Their estimated initial activities were between 10- and 100-fold lower than those in water. Complete hydrolysis of the TG (measured as the hydrolysis of at least one ester bond in each molecule) was achieved, whereas only 40–60% of the phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were hydrolyzed. Lipase SP-435 was inactive against TG in hexane but hydrolyzed PC at a rate comparable to that seen in water, and it achieved complete hydrolysis of this substrate. Amano phospholipase B was inactive against TG in hexane but completely hydrolyzed the PC. The abilities of the enzymes to hydrolyze the TG, PC, and PE components of soybean soapstock, a by-product of edible oil production, were also examined. Lipozyme IM-20 hydrolyzed all the TG and a fraction of the PL in soapstock. SP-435 and AY-30/Celite were active only on soapstock that had been acidified prior to being dissolved in hexane. SP-435 displayed significant activity only toward PE under these conditions, whereas AY-30/Celite was active only toward TG. Phospholipase B was inactive against soapstock in hexane. The identity of the acid used in the acidification of soapstock affected the degree of hydrolysis by AY-30/Celite, with nitric and hydrochloric acids giving the best activity.     

聚酰胺固化环氧树脂的热分解动力学研究

利用热重分析(TG)采用不同升温速率(10,15,20,25℃/min)分别在空气和氮气气氛下对聚酰胺固化环氧树脂热稳定性进行了研究.采用Coats-Redfem和Ozawa热分析处理动力学数据的方法,计算了环氧树脂热分解反应活化能E、反应级数n及频率因子A.求得空气气氛下5%～30%的失重率下反应表观活化能在70.3...     

Chemical functionalization of polyamide 6.6 fabrics

Polyamide 6.6 (PA 6.6) fibers, produced from adipic acid and hexamethylenediamine, are among the most consumed synthetic textile fibers used for garments. Fibers are hydrophobic, which makes dyeing difficult and affects wearing comfort. In the present work, chemical treatments of PA 6.6 fibers were carried out and compared with respect to their effect on fiber properties and obtained surface modifications. Scoured knitted PA 6.6 fabrics (opaque) were treated with hydrochloric acid (0–3 M) and sodium hydroxide (3 M) for up to 3 h at 60 °C. The fibers were characterized with respect to bulk and surface modifications such as amino and carboxyl end groups, superficial dyeing below the T_G of the fiber, surface structure with SEM and AFM analysis. Furthermore a new analytic procedure for the determination of surface amino groups was tested. Both chemical treatments resulted in a significant increase in the amount of amino groups on the fiber, but especially the treatment with HCl 3 M caused a more drastic surface modification of the fibers, however, not only restricted to the fiber surface. AFM and SEM analysis have shown a significant change in surface roughness on the nanoscale, which in addition to the creation of surface functional groups increases the fiber’s hydrophilicity and reactivity.     

Characterization of potentially bioreactive soil organic carbon and nitrogen by acid hydrolysis

Studies determined the potential of acid hydrolysis for estimating the bioreactive fraction of organic carbon in soils (SOC). Three soils (clay loam, silt loam, and sandy loam) were hydrolyzed with 1 M or 6 M HCl under reflux for up to 24 h. Results showed that 1.7 to 3.2 % of SOC could be liberated as CO₂ from the acid hydrolysis of soil. This readily hydrolyzed fraction should be a part of the bioreactive SOC. Higher amounts of soluble SOC and N as well as CO₂ were released from all soils by 6 M HCl than by 1 M HCl. Soluble SOC and N contents in both 1 M HCl and 6 M HCl hydrolysates of all soils increased rapidly during the initial 2 hours of hydrolysis, and then increased very gradually. The amounts of CO₂-C evolved correlated with the amounts of NH₄-N released during the acid hydrolysis (r = > 0.88). The ratio of SOC to soluble N was lower in 6 M HCl hydrolysate than in 1 M HCl. Hydrolysis of soil by 1 M HCl for 4 h appeared to be a promising approach for estimating the more bioreactive pools of SOC and N. This revised version was published online in August 2006 with corrections to the Cover Date.     

近临界水中禽类废弃物超低酸水解成氨基酸

为寻求禽类废弃物的有效利用途径,对其进行在近临界水中超低酸水解制备氨基酸的工艺优化及反应动力学研究。以鸡肠为原料,氨基酸总收率为指标,采用正交试验设计对反应温度、反应时间、硫酸浓度3种水解条件进行研究。实验结果表明,近临界超低酸水解法最佳的工艺条件为:T=533 K,t=28 min,c(H2SO4)=0.002 mol/L,氨基酸的总收率为11.49%。在反应温度分别为473,503,533,553 K,c(H2SO4)=0.002 mol/L条件下,鸡肠在近临界水中水解为氨基酸的动力学表观速率常数分别为1.52×10-2,3.35×10-2,11.58×10-2,14.01×10-2。其反应级数为1.52,反应活化能为64.44 kJ/mol,指前因子为1.91×105。     

The hydrolysis of phosphatidylcholine by an immobilized lipase: Optimization of hydrolysis in organic solvents

The ability of a commercial immobilized lipase preparation (Lipozyme) to hydrolyze the fatty acyl ester bonds of soybean phosphatidylcholine in organic media was investigated. Response surface methodology, based on a Modified Central Composite design, was employed to examine the effects on hydrolysis of solvent polarity, water, pH, duration and temperature of incubation, and the amounts of substrate and catalyst. A second-order regression model was developed, which allows evaluation of the effects of these parameters, alone or in combination. Hydrolysis increased in a relatively straightforward manner in response to increases in incubation time and the amount of catalyst and was approximately constant over the range of substrate amounts studied. Solvent polarity had a profound effect on the degree of hydrolysis, and the qualitative and quantitative degrees of this effect were dependent upon the values of the other parameters studied. Conditions were identified where enzyme activity was strong in either nonpolar or polar solvents, with activity increasing as the polarity of the medium increased. Enzyme activity was minimum at about 37°C, increasing below and above this temperature. Activity was not affected by the presence of acid or base in the reactions. Increasing amounts of water stimulated enzyme activity in solvents more polar than hexane, while in less polar solvents water inhibited activity.     

流延法制备聚酰亚胺薄膜工艺研究

以均苯四甲酸二酐、4，4＇-二胺基二苯醚为原料，通过缩聚反应制备了聚酰胺酸，采用凝胶渗透色谱（GPC）考察了反应时间对产物重均摩尔质量的影响；测定了干燥过程中聚酰胺酸凝胶膜溶剂含量的变化；并利用电子万能试验机研究了聚酰胺酸薄膜的拉伸工艺。结果表明：聚酰胺酸的适宜反应时间为6h，此时其重均摩尔质量趋于稳定。随着干燥温度的升高和时间的延长，凝胶膜的溶剂含量逐渐减少。分析得到较好的拉伸条件是干燥温度为130℃，溶剂质量分数为30％左右的凝胶膜。聚酰亚胺薄膜经拉伸后，其拉伸强度和模量均随拉伸比的增大而增加。     

Synthesis of a sulfonic acid functionalized acidic ionic liquid modified silica catalyst and applications in the hydrolysis of cellulose

A sulfonic acid functionalized acidic ionic liquid modified silica catalyst was prepared in 68% overall yield from 3-chloropropyl silica by a simple two step method involving nucleophilic substitution of chlorine with imidazole, then condensation with 1,3-propanesultone and acidification using HCl. This silica supported acid catalyst was shown to be effective in the hydrolysis of cellulose (DP ∼ 450) dissolved in 1-n-butyl-3-methylimidazolium chloride at 70 °C, producing glucose and total reducing sugars in 26 and 67% yields respectively.     

Zirconium phosphonates layered structure catalysts with organic acid pendants 2. Catalytic properties

Catalytic properties of Zirconium phosphonates layered structure (ZPLS) catalysts with organic sulfonic acid pendant groups have been studied. The NaOH titration demonstrated the presence of sulfonic acid groups. The ZPLS contained acid sites per weight similar to or slightly less than those for cation exchanged resins. The hydrolysis of ethyl acetate and the esterification of acetic acid with ethanol were studied as test reactions. Accessibility of the reactants to the acid sites present in the interlayer spacing of ZPLS was a determining factor for the activity. Thus the activity depended on the ease of swelling and particle size of the ZPLS.     

生物质稀酸水解动力学及其反应器的研究进展

木质纤维素类生物质经过稀酸水解可制取可发酵性糖,进而形成糖平台,生产纤维素乙醇等能源和化工产品。不同类型和结构的反应器中,原料的水解行为不同,被水解的效果也就不同。本文从稀酸水解反应器和反应动力学两方面入手,综述了近年提出的木质纤维素类生物质稀酸催化动力学模型和反应器。通过比较不同反应器的水解效果,推测出多步处理、逆流过程、动态反应是木质纤维素类生物质稀酸高效水解反应的发展趋势。     

酸催化蔗糖水解的动力学研究

利用旋光度与蔗糖反应体系浓度的关联,研究了盐酸、硫酸、磷酸、醋酸等不同酸催化剂以及不同浓度的盐酸在不同温度下对蔗糖水解反应速率的影响。结果表明,不同酸催化剂对蔗糖水解起催化作用的是氢离子;[H]+从3 mol/L变化到4 mol/L时,蔗糖水解反应从一级反应近似转变为二级反应;催化剂降低了反应的活化能,加快了反应速率;酸催化蔗糖水解最佳条件是盐酸,浓度为3 mol/L,反应温度为45℃。     

Reaction mechanisms and kinetics of xylo‐oligosaccharide hydrolysis by dicarboxylic acids

Hydrothermal pretreatment of lignocellulosic materials generates a liquid stream rich in pentose sugar oligomers. Cost‐effective hydrolysis and utilization of these soluble sugar oligomers is an integral process of biofuel production. We report integrated rate equations for hydrolysis of xylo‐oligomers derived from pretreated hardwood by dicarboxylic maleic and oxalic acids. The highest xylose yield observed with dicarboxylic acids was 96%, and compared to sulfuric acid, was 5–15% higher with less xylose degradation. Dicarboxylic acids showed an inverse correlation between xylose degradation rates and acid loadings unlike sulfuric acid for which less acid results in less xylose degradation to aldehydes and humic substances. A combination of high acid and low‐temperature leads to xylose yield improvement. Hydrolysis time course data at three different acid concentrations and three temperatures between 140 and 180°C were used to develop a reaction model for the hydrolysis of xylo‐oligosaccharides to xylose by dicarboxylic acids. © 2012 American Institute of Chemical Engineers AIChE J, 59: 188–199, 2013     

Synthesis of terminal Si-H irregular tetra-branched star polysiloxanes. Pt-catalyzed hydrosilylation with unsaturated epoxides. Polysiloxane films by photo-acid catalyzed crosslinking

Acid catalyzed insertion of octamethylcyclotetrasiloxane (D₄) into the Si-O bonds of tetrakis(dimethylsiloxy)silane leads to irregular tetra-branched star polymers—tetrakis(ω-dimethylsiloxy)poly(dimethylsiloxy)silane (I). The terminal Si-H bonds of I have been modified by Pt-catalyzed hydrosilylation with 4-vinylcyclohexane-1,2-epoxide to yield a tetra-branched star polydimethylsiloxanes (PDMS) with terminal 2′-ethyl-4-cyclohexanyl-1,2-epoxide groups (II). Solutions of this material and a catalytic amounts of diaryl iodonium hexafluoroantimonate, a photo-acid catalyst, were cast onto glass slides and subsequently irradiated. This results in formation of crosslinked PDMS films (V). The soluble tetra-branched PDMS stars have been characterized by ¹H, ¹³C, and ²⁹Si NMR as well as by IR spectroscopy. Their molecular weight distributions have been determined by gel permeation chromatography (GPC), multi-angle laser light scattering (MALLS), and end groups analysis. Their viscosities were measured with a Brookfield viscometer. The thermal stability of the polymers and the crosslinked films were determined by TGA. The glass transition temperatures (T_g)s of the polymers were determined by DSC. The loss (G″) and storage (G′) shear moduli of the films were determined by DMTA. Surface properties of the films were determined by measurement of static contact angles.Similar star polymers, tetrakis(dimethylsiloxy)poly[3′,3′,3′-trifluoropropylmethylsiloxyl]silanes (III) were prepared by acid catalyzed equilibration of tetrakis(dimethylsiloxy)silane with 1,3,5-trimethyl-1,3,5-tris(3′,3′,3′-trifluoropropyl)cyclotrisiloxanes (D₃^F). These were, likewise, modified by Pt-catalyzed hydrosilylation with 4-vinylcyclohexane-1,2-epoxide. Films (VI) of this material were similarly prepared by photo-acid catalyzed crosslinking.     

酸化水解-活性污泥-生物接触氧化工艺处理有机污水

介绍了采用酸化水解——活性污泥——生物接触氧化工艺处理含有山梨醇、甘露醇、蔗糖、醋酸乙烯、甲基纤维素的有机污水。该工艺具有出水水质稳定，操作简单、管理方便，能耗低等优点，是处理该类有机污水的有效方法。