Separation of Ethyl Esters of Eicosapentaenoic Acid and Docosahexaenoic Acid by Circulating Liquid Membranes Using Silver Nitrate as a Carrier. Uphill Transport by Use of Temperature and Solvent Dependencies of Distribution Ratio

Abstract

Experiments on the separation of ethyl ester of eicosapentaenoic acid (EPA-Et) and that of docosahexaenoic acid (DHA-Et) contained in ethyl ester of bonito oil (bonito oil-Et) were performed using circulating liquid membranes (CIRLMs) containing sliver nitrate as a carrier. In this liquid membrane system an aqueous silver nitrate solution was circulated between a stirred vessel containing an organic solution of bonito oil-Et and another stirred vessel containing a receiving organic solvent. Using the CIRLM, two types of uphill facilitated transport of EPA-Et and DHA-Et in bonito oil-Et were demonstrated. The first type utilizes the distribution ratio of EPA-Et and DHA-Et, defined as the ratio of the concentration in the aqueous phase to that in the organic phase at equilibrium, which is remarkably dependent on the temperature, and the second uphill transport was based on the fact that the distribution ratio is considerably dependent on the solvent of the organic phase. A model of permeation through the circulating liquid membrane was proposed to explain the experimental results.     

Separation of Polyunsaturated Fatty Acids with Silver Nitrate Using a Hollow-Fiber Membrane Extractor

Abstract

Solvent extraction of ethyl esters of polyunsaturated fatty acid such as eicosa-pentaenoic acid (EPA) and docosahexaenoic acid (DHA) was performed with an aqueous silver nitrate solution using a microporous hydrophobic hollow-fiber membrane extractor. The mixture of four kinds ethyl esters of fatty acids involved in fish oil was employed as a model solution of fish oil. Also studied was the extraction equilibria of these fatty acids at various conditions. It was demonstrated from the experimental results that EPA and DHA ethyl esters could be satisfactorily separated from ethyl esters of lower fatty acids such as oleic and palmitic acids. In addition, the effects of silver and ester concentrations in aqueous and organic feed solutions on the apparent permeabilities of fatty acids ethyl esters were investigated in extraction and stripping stages, respectively. It was concluded that the permeation rate was controlled by the diffusion across the membrane and the laminar boundary layer in the inner and outer sides of the hollow fiber.     

负载Ag~+ D72树脂色谱柱分离纯化花生四烯酸工艺的建立

目的建立负载Ag+D72树脂色谱柱分离纯化花生四烯酸(Arachidonic acid,AA或ARA)的工艺。方法采用负载Ag+D72树脂色谱柱对微生物油脂中的ARA进行分离纯化,确定最佳分离纯化参数,利用气相色谱法检测ARA的含量。结果负载Ag+D72树脂的最大饱和吸附量约为9 mg/g干树脂,在吸附温度0℃、不饱和脂肪酸甲酯上样质量浓度5 mg/ml,5%丙酮正己烷溶液(体积比)洗脱、解吸温度30℃、洗脱流速2 ml/min的条件下,ARA的纯度达89.4%,收率达79.3%。结论负载Ag+D72树脂色谱柱可有效分离纯化微生物油脂中的ARA,为进一步生产高纯度的ARA,进而规模化生产ARA产品提供了参考。     

Facilitated transport of ethyl docosahexaenoate through solution-cast perfluorosulfonated ionomer membranes

The facilitated transport of ethyl docosahexaenoate (DHA-Et) through the thin solution-cast perfluorosulfonated ionomer membranes has been studied. The carrier of DHA-Et was silver ion and was immobilized in the support ionomer membrane by electrostatic forces. In this system, the feed phase, membrane phase, and receiving phase had the same solvent. This system was already proved to be highly stable in our previous work. When ethanol/water (85/15) was used as the solvent, the DHA-Et permeance in the cast membrane was about four times higher than that in the commercial Nafion® 117 membrane, due to the smaller membrane thickness. In the case of acetone solvent, a high selectivity of DHA-Et to ethyl oleate of 42 and a high facilitation factor of 153 were obtained. These membrane performances were superior to those of the Nafion® 117 membrane. The effects of membrane preparation conditions, such as annealing temperature and kinds of polar solvents added to the ionomer solution before annealing, on the membrane performance was investigated in detail. Furthermore, small-angle X-ray scattering (SAXS) measurement was carried out to study the membrane structure. The experimental result suggests higher crystallinity in the cast membrane annealed at higher temperature. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 961–968, 1999     

大孔树脂富集多舌飞蓬总咖啡酸酯的工艺研究

摘要：考察了13种不同极性的大孔树脂对多舌飞蓬中总咖啡酸酯的富集纯化能力,发现极性树脂NKA-2的静态吸附率为92.51%、解吸率为98.51%,明显优于其他树脂。进一步以NKA-2极性树脂对多舌飞蓬总咖啡酸酯进行静态吸附与动态吸附实验,结果表明,最佳上样质量浓度为300 g/L,最佳上样流速为2 BV/h,树脂吸附容量为6 mL/g,即单位NKA-2树脂可以处理1.8 g生药。解吸实验结果表明,体积分数为60 %的乙醇溶液更有利于多舌飞蓬总咖啡酸酯的洗脱,用量为8 BV。用上述条件对多舌飞蓬总咖啡酸酯富集纯化,使总咖啡酸酯的纯度由18.09 %提高到58.06 %,回收率高达94.78 %。说明NKA-2型大孔吸附树脂综合性能良好,可用于多舌飞蓬中总咖啡酸酯成分的富集和纯化。     

mufiltration of polydispersed suspension by a membrane screen/hollow-fiber composite module

Membrane and hollow-fiber technologies have widely been used in pure water production, and are increasingly used in conventional water and wastewater treatment for solid—liquid separation. A major challenge to these applications is to prevent or reduce particle fouling so that the membrane or hollow-fiber modules can be operated at a higher permeation flux and over a longer period of time. In this study, a membrane screen/hollow-fiber composite module has been developed for the mufiltration of polydispersed suspensions. The module combines a cylindrical membrane of larger pores as a screen and a bundle of hollow fibers of smaller pores for polishing treatment. Both cross-flow and dead-end filtrations occur in the same module. Experiments were conducted at various concentrations with kaolin particles of size ranging from 0.5 μm to 10 μm. The results showed that the membrane screen effectively removed larger particles from the permeating flow and reduced solid loading to the hollow fibers. As a result, the composite module generated considerably higher permeation flux, as compared to a similar hollow-fiber module without the membrane screen. It was found that larger particle deposition was more significantly affected by the cross flow, and initially deposited particles contributed greater specific resistance to the permeating flow.     

Dietary docosahexaenoic acid suppresses inflammation and immunoresponses in contact hypersensitivity reaction in mice

This study was designed to examine the immunomodulatory effects of dietary docosahexaenoic acid (DHA) in the absence of eicosapentaenoic acid (EPA). We investigated the effects of feeding dietary DHA ethyl ester (DHA-Et) (97% pure) at levels of 4.8 wt% of the total diet and of feeding EPA ethyl ester (EPA-Et) (99% pure) at 4.8 wt% on the inflammatory response in the challenge phase of the contact hypersensitivity reaction (CHR) in the ears of mice sensitized with 2,4-dinitro-1-fluorobenzene (DNFB). The effect of DHA-Et on T lymphocytes at the CHR site was examined using anti-CD4 antibodies. Furthermore, we examined the cytokines formed at the CHR site on the mRNA level. It was found that 24 h after the challenge, DHA-Et but not EPA-Et reduced the ear swelling. Infiltration of inflammatory cells, in particular, CD4-positive T lymphocytes, into the ears in the challenge phase of CHR was observed. DHA-Et reduced the infiltration of CD4-positive T lymphocytes into the ears. DHA-Et also decreased the expression of interferon-γ, interleukin (IL)-6, IL-1β, and IL-2 mRNA in ears. These observations suggest that DHA, but not EPA, may exert an antiinflammatory and immunosuppressive effect. The immunosuppressive effectiveness of fish oil may be attributed mainly to DHA.     

Esterification of lauric acid using lipase immobilized in the micropores of a hollow-fiber membrane

A porous anion-exchange hollow-fiber membrane was prepared by radiation-induced graft polymerization and chemical modification to immobilize lipase for enzymatic reaction in an organic solvent. The amount of anion-exchange group introduced to the porous hollow-fiber membrane was 2.5 mol/kg_fiber. A lipase solution was allowed to permeate through the porous anion-exchange hollow-fiber membrane, and lipase molecules that adsorbed onto the grafted polymer brush were cross-linked with glutaraldehyde. The lipase was immobilized at a density of 0.14 kg_lipase/kg_fiber, which was equivalent to a degree of multilayer binding of 20. Esterification was carried out by passing a solution of lauric acid and benzyl alcohol in anhydrous issoctane through the lipase-immobilized membrane, and lipase activity was determined. A reaction percentage of 50% was achieved at space velocity 68 h⁻¹. The maximum immobilized lipase and native lipase activities were 8.9 and 0.38 mol/(h·kg_lipase), respectively. Thus, the activity of the immobilized lipase was 23.4 times higher than that of the native lipase.     

Pr0.6Sr0.4Co0.2Fe0.8O3-δ中空纤维陶瓷膜的制备及其透氧性能

采用改进的溶胶-凝胶法制备了一系列陶瓷粉体Pr1-xSrxCo1-yFeyO3-δ(x=0.2、0.4、0.6;y=0.2、0.4、0.6、0.8).运用相转化/烧结技术制造出了Pr0.6Sr0.4Co0.2Fe0.8O3-δ(PSCF6428)中空陶瓷纤维膜.用热分析、X射线衍射仪、扫描电镜、X射线能谱等技术对制备的...     

反渗透过程溶质脱除率方程

<正>溶解扩散理论、摩擦模型和表面力-孔流模型假设稳态时膜中溶质通量恒定“-”。本文分 析了该假设存在的理论依据,并基于膜的吸附-扩散模型’‘’建立了反渗透过程溶质脱除率方 程。     

动态膜在错流微滤系统中的应用

利用6000目的高岭土作为动态膜涂膜材料,在相同的条件下过滤活性污泥和二级出水.实验结果显示,动态膜过滤在出水水质和通量方面明显优于直接过滤,而处理二级出水在膜通量方面没有优势.清洗实验结果表明动态膜能有效降低膜内部污染,并能恢复到新膜通量的90%.污泥浓度越大,通量越小.提高膜面流速和增加压力都能有效的提高膜通量,但提高膜面流速更经济.     

载银介孔SBA-15吸附剂的制备及其对脂肪酸甲酯的吸附研究

以介孔分子筛SBA-15作为载体,在3-氨基丙基三乙氧基硅烷(APTS)对SBA-15表面修饰的基础上负载银离子制备Ag⁺-APTS/SBA-15吸附剂,采用氮气吸附-脱附、X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、透射电镜(TEM)、扫描电镜-能谱(SEM-EDS)对吸附剂进行表征,并将吸附剂应用于混合脂肪酸甲酯的分离以考察其吸附性能。氮气吸附-脱附、XRD和TEM分析结果可以看出,制备的吸附剂具有规则有序孔道结构;FT-IR数据显示,介孔SBA-15表面被APTS成功修饰;SEM-EDS结果表明,银离子成功负载到载体SBA-15上;对混合脂肪酸甲酯吸附研究表明,该吸附剂对不饱和脂肪酸甲酯(UFAMEs)吸附效果较好,且随着银离子负载量的增加以及UFAMEs双键数的增多,吸附效果增强;当银离子负载量为25%时,吸附剂对亚麻酸甲酯吸附率高达53.47%。     

萃淋树脂处理含银离子废水工艺研究

为处理电镀含银离子废水,回收金属银,采用磷酸二异辛酯（P204）萃淋树脂吸附银离子.研究了pH值、温度、树脂投加量、流速对吸附效果的影响.结果表明,萃淋树脂静态吸附量可达145 mg/g,优化的吸附条件是pH值为3,温度为20℃,流速为5 BV/h.适宜脱附液为氨水（20％）,流速为5 BV/h,脱附液体积为8 BV,脱附率可达87％,脱附液可以用于回收银.该工艺能够较好地满足含银离子废水处理要求.     

纳米SiO2载银抗菌剂的研究

以化学沉淀法制备得到多孔纳米SiO2,采用吸附法在其表面负载银,用载银的粉体抑菌圈直径表征抗菌性能。研究了吸附时间、硝酸银浓度及吸附温度与负载量的关系,并考查了焙烧温度与抗菌性能的关系。     

Water–ethanol permseparation by pervaporation through the plasma graft copolymeric membranes of acrylic acid and acrylamide

Acrylic acid was copolymerized with acrylamide onto the porous polypropylene film which had been previously treated by glow discharge plasma, and the partially ionized membranes were prepared with treating in dilute sodium hydroxide aqueous solution. Using these membranes with different ratios of polyacrylate ion, water–ethanol permseparation was investigated. The membranes were water-permselective because of the hydrophilicity, and the permselectivity was increased by ionization generally for the feeds with ethanol concentration more than 50%. In the lower ethanol concentration range, the permselectivity was not so good because of the much higher permeation rate. When the permselectivity was evaluated by the products of separation factor (a) and Flux (Q), the copolymerized membranes with the acrylic acid mixing at 0.4 were superior to the ion-exchange membranes, although somewhat inferior to the ionized membranes of acrylic acid grafting which had been attempted previously. In the ionized membrane of the copolymer, the activation energy for permeation lied between 4.2 and 5.5 kcal/mol, and was much smaller than that of the neutral membranes before ionization; i.e., the decrease of flux was depressed even at the lower temperature.     

Facile modification of polysulfone hollow-fiber membranes via the incorporation of well-dispersed iron oxide nanoparticles for protein purification

Protein existence in wastewater is an important issue in wastewater management because proteins are generally present as contaminants and foulants. Hence, in this study, we focused on designing a polysulfone (PSf) hollow-fiber membrane embedded with hydrophilic iron oxide nanoparticles (IONPs) for protein purification by means of ultrafiltration. Before membrane fabrication, the dispersion stability of the IONPs was enhanced by the addition of a stabilizer, namely, citric acid (CA). Next, PSf–IONP–CA nanocomposite hollow-fiber membranes were prepared via a dry–wet spinning process and then characterized in terms of their hydrophilicity and morphology. Ultrafiltration and adsorption experiments were then conducted with bovine serum albumin as a model protein. The results that an IONP/CA weight ratio of 1:20 contributed to the most stable IONP dispersion. It was also revealed that the membrane incorporated with IONP–CA at a weight ratio of 1:20 exhibited the highest pure water permeability (58.6 L m⁻² h⁻¹ bar⁻¹) and protein rejection (98.5%) while maintaining a low protein adsorption (3.3 μg/cm²). The addition of well-dispersed IONPs enhanced the separation features of the PSf hollow-fiber membrane for protein purification. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47502.     

中空纤维膜低压超滤处理含油废水的数学模拟

提出一个不可忽略轴向压力降和膜渗透速率轴向变化的中空纤维膜低压超滤处理含油废水的传质模型 ,采用正交配点法并结合MATLAB软件进行模拟 ,解出速度分布和浓度分布 ,得到超滤速率的变化规律 ,与实验数据吻合很好 .用模拟结果讨论Peclet数对超滤的影响 ,并分析中空纤维丝内径向速度分布 ,为超滤膜及工艺条件的选择提供了重要依据 .     

Reinigung lösungsmittelhaltiger Abluft – alternative Möglichkeiten

Purification of solvents containing air – Alternative methods. Different processes are used for the purification of solvents containing air: condensation, absorption, adsorption, combustion, membrane permeation, and biofilters or bioscrubbers. The processes will be explained by examples. The specifications required by “TA Luft” often cannot be reached only by condensation and membrane permeation. The success of absorption depends on the scrubbing liquid. Glycol ethers are useful scrubbing liquids – especially for chlorinated hydrocarbons. The choice of the process depends on the volume flow rate, the solvent concentration, and the kind of solvent. Recycling of the solvents reduces the costs of the process.     

Microfluidic modeling and simulation of flow in membrane microreactors

We study the development of a mathematical model that describes isothermal microfluidic steady flow in a membrane microreactor, i.e., a silicon microreactor that houses a permeable membrane in one wall. The model employs the Navier-Stokes equation with appropriate boundary conditions for fluid permeation through the membrane and velocity slip at the walls to account for high Knudsen number. The model equations are solved analytically using finite Fourier transforms. The model solution is used to evaluate the effect of fluid permeation through the membrane and the Knudsen number on the velocity profile and pressure drop. For the simplified cases of no permeation and/or no slip, the derived solution is in excellent agreement with published experimental and theoretical results available in the literature. The utility of the model is illustrated by applying the results to a membrane microseparator used to separate hydrogen from the other effluents in a microreformer.     

Multi-technique integration separation frameworks after steam reforming for coal-based hydrogen generation

Coal-based H_2 generation has abruptly increased in recent years.The PSA-VPSA-SC process is the matured and standard framework for H_2 purification and CO_2 capture in many existing plants,including normal and vacuum pressure swing adsorption units in series(PSA-VPSA),and shallow condensation unit(SC).However,this standard process is frequently subjected to low H_2 recovery ratio and high purification cost.In this work,H_2-selective and C02-selective membrane units,i.e.,HM and CO_2 M,are attempted to support the standard process and ameliorate constraints.In the beginning,HM unit is arranged after VPSA to enhance H_2 recovery from the decarbonized stream,i.e.,the PSA-VPSA-SC/HM process.As a result,H_2 recovery ratio can be enhanced significantly from 83% to 98%.In the following,VPSA is replaced with CO_2 M unit to reduce investment and operation cost,i.e.,the PSA-CO_2 M-SC/HM process.Accordingly,the specific purification cost is diminished from 33.46 to 32.02 USD·(10~3 m~3 H_2)~(-1),saved by 4.3%,meanwhile the construction cost is falling back and just a little higher than that for the standard process.In the end,another CO_2 M unit is launched before PSA,i.e.,the CO_2 M-PSA-CO_2 M-SC/HM process,which could unbundle CO_2 enrichment partially from H_2 purification,and then save more investment and operation cost.In comparison with the standard process,this ultimate retrofitted process can be superior in all the three crucial indices,i.e.,recovery ratio,investment,and specific purification cost.On the whole,coal-based H_2 generation can be ameliorated significantly through high efficient H_2-selective and CO_2-selective membrane units.