A novel technique for separating glycerine from palm oil-based biodiesel using ionic liquids

Biodiesel production from abundant bio-sources has drawn the attention of the academic as well as the industrial communities in recent years. However, one of the most serious obstacles for using biodiesel as an alternative fuel is the complicated and costly purification processes involved in its production. The difficulties involved in the separation of glycerine and other un-reacted reactants and by-products necessitate the development of new competent low cost separation processes for this purpose. In this work, a low cost quaternary ammonium salt-glycerine-based ionic liquid is proposed as a solvent for extracting glycerine from the transesterification biodiesel product. The separation technique was tested on palm oil-based produced biodiesel with KOH as a reaction catalyst. The study investigated the effect of DES:biodiesel ratio and the DES composition on the efficiency of the extraction process. The lab scale purification experiments proved the viability of the separation technique with a best DES:biodiesel molar ratio of 1:1 and a DES molar composition of 1:1 (salt:glycerine). The purified biodiesel fulfilled the EN 14214 and ASTM D 6751 standard specifications for biodiesel fuel in terms of glycerine content. A continuous separation process is suggested for industrial scale application.     

Separation and determination of mono-, Di-, and triglycerides in monoglyceride concentrates

Summary Monoglyceride concentrates are quantitatively separated into mono-, di-, and triglyceride components on silica gel columns by an adsorption chromatographic technique. The separated glycerides are determined gravimetrically. The adsorption on silica gel is dependent on the number of hydroxyl groups in the molecule, and the influence of unsaturation and chain length is minimized. Combinations of benzene and ethyl ether are used for elution, thus preventing isomerization, which frequently results when polar solvents such as alcohols are used. The procedure for the chromatographic separation is simple and straightforward. The equipment used is easily obtainable. The silica gel adsorbent requires only adjustment of its water content before use. Mixtures of both saturated and unsaturated glycerides and those having different fatty acid chain length have been separated. Known mixtures have also been analyzed. For a known mixture containing 15% tripalmitin, 45% distearin, and 38% monopalmitin the average deviations from the calculated values were 0.4%, 0.2%, and 0.6%, respectively     

Vibroacoustical selective agglomeration of coal slimes

Coal slimes from coking coal with an average ash content of about 45% and difficult separation characteristics have been studied. Investigations have also been carried out on two artificial mixtures of gangue and coal of low ash content. Two kinds of agitation have been tested: mechanical—rotational (with an impeller mixer) and vibroacoustical (with vibrating band) at a frequency of 50 Hz and an amplitude of 1 – 2 mm. Vibroacoustical agitation was much more efficient than mechanical-rotational. Second-degree orthogonal-central-compositional planning was used for studying slimes of appropriate size (−0.063 mm). In the most successful test with natural slimes, an efficiency of separation of 34.41% was obtained with the following technological parameters: yield of concentrate 27.93%, ash content of concentrate 22.00%, yield of refuse 72.07%, ash content of refuse 54.30%, the ash content of the run-of-mine coal being 45.28%. These results are close to the best ones obtained with the same slimes by fractional analysis in a liquid of density 1500 kg/m³. In this case, an efficiency of separation of 39.18% was obtained with yield of concentrate 35.04%, ash content of concentrate 24.01%, yield of refuse 64.96%, and ash content of refuse 56.01%.

The experiments on selective agglomeration have been carried out using kerosene at 14.8% consumption with respect to solids. The investigations are of a preliminary character.     

Solubility of hydrogenated peanut oil in peanut oil

Conclusions Data obtained on the solubility of hydrogenated peanut oil in refined peanut oil and the behavior of the mixtures on cooling indicate that freedom from oil separation on storage is largely determined by the nature as well as the amount of solid crystals present in the oil. The results suggest that the best procedure for prevention of oil separation would involve shockchilling the molten mixture to produce the finely divided metastable crystalline modification followed by tempering at such a temperature as to permit transformation of the crystals into the more desirable higher-melting form without changing the finely divided state necessary for improved palatability. The data imply that under controlled conditions any amount of the high-melting modification of the hard fat incorporated in peanut oil above the solubility temperature in excess of 2% should produce a mixture free from oil separation under average storage conditions. The choice of the actual concentration of the hard fat, above the minimum amount, would depend upon the degree of plasticity desired. Ambient temperature to which the mixture is likely to be subjected will influence to a considerable extent the selection of the hard fat content. The information obtained is of fundamental importance in connection with the problem of oil separation in peanut butter. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Air dispersion of starch-protein mixtures: A predictive tool for air classification performance

Milling and air classification is a well-known procedure to obtain protein and starch enriched fractions from cereals and grain legumes. Adhesion of small protein particles to larger starch granules adversely affects the separation efficiency during air classification. To gain insight into this phenomenon the dispersion of bimodal mixtures of starch granules and fine protein particles in an air stream was studied.Using a method to correct for the number of small starch particles in the protein fraction, the dispersability of protein/starch mixtures was determined. The type of protein and, particularly, of starch may affect dispersability. The effect of starch type is not only caused by differences in granule size; likely other properties such as roughness are also involved. Increasing protein content enhances dispersability but does not seem to have an effect on the adhesion between starch and protein particles itself. An increase in adhesion by relative humidity of 90% results in a decreased dispersability.The dispersability of the mixtures was related to their performance upon air classification. Both the separation efficiency and tau were strongly related to dispersability (R² = 0.86 and 0.88 respectively). Hence, the dispersability, which can easily be measured, is a powerful tool to predict the air classification performance for separation of starch and protein.     

Purification of glycerol/water solutions from biodiesel synthesis by ion exchange: sodium and chloride removal. Part II

BACKGROUND: Equilibrium studies were carried out with the aim of finding the basic design parameters for ion exchange plants using a glycerol phase obtained from biodiesel production. The uptake of sodium and potassium ions on a strongly acidic ion exchanger, Amberlite IR‐120, in the proton form from glycerol/water mixtures has been studied. The effect on the selectivity towards sodium of the percentage of water in glycerine/water mixtures on the macroporous resin Amberlite 252 has been analyzed. Finally, chloride removal by a strongly basic anionic‐exchange resin Amberlite IRA‐420 at three different temperatures has been studied. RESULTS: The strongly acidic ion exchanger Amberlite IR‐120 exhibits higher selectivity for potassium versus sodium ions. The ideal mass action law model was able to fit the experimental equilibrium data. The equilibrium data obtained at different percentages of water in the glycerine/water mixture indicate that as the water content increased the resin selectivity for sodium uptake is reduced. The selectivity of the anion exchange resin Amberlite IRA‐420 for chloride ions decreases with temperature. The ideal mass action law was accurate enough to fit the equilibrium data of the three systems and allowed the equilibrium thermodynamic properties to be obtained. CONCLUSIONS: These results confirm that macroporous resin Amberlite 252 could be a good choice to remove sodium ions from glycerol/water solutions with a high salt concentration and also that a strongly basic anionic‐exchange resin could be used for chloride removal. Copyright © 2009 Society of Chemical Industry     

A study using classical or membrane separation in the biodiesel process

Biodiesel is a clean burning biofuel produced from renewable resources (straight vegetable oil, animal oil/fats, tallow and waste cooking oil), which can be blended at any level with petroleum diesel to create a blend of biodiesel.The EU has adopted a series of directives to promote and to represent some of the most important renewable energy sources out of biofuels also covering biodiesel as well.The main processing stages currently applied for biodiesel technology are represented by transesterification, neutralization of mixture, phase separation, biodiesel and glycerine purifications. The reaction, generally occurring in a two-stage mixer-settler unit, arises some difficulties for clear cut separations.A new alternative technology, using hydrophobic porous membranes, can be used to prevent bulk mixing of the two phases and facilitate contact and mass transfer of species between the two phases.The glycerine side stream (roughly representing 10% of biodiesel) typically contains a mixture of many components, which are generally difficult to separate. Current methods for glycerine purification are complicated and conducted with higher costs.In this case, the new technology provides an economical solution for the purification of crude glycerine stream combining the high efficiency of electro-dialysis and nano-filtration processes.A comparative cost approach based on available information is sketched. Also, some examples sustain the aim of the study.     

HPLC optimization of the separation of explosives and propellant components with an octadecyl phase by computer simulation

High performance liquid chromatography (HPLC) is used in a large extent for environmental analysis. In this field many components have to be determined at the same time, but it is difficult to find the optimum separation conditions. Therefore, retention times of explosives and propellant components were determined at different solvent compositions of methanol/water and different temperatures on a column with an octadecyl phase. From the data constants were calculated for solvent and temperature dependence. With the determined data different column conditions were simulated by computer and the separation was optimized. The optimal separation was verified experimentally and compared with the calculated values. The deviation from calculated and experimental retention times lies as a rule below 2% and has a maximum of approximately 3.3%. Thus, separation of substance mixtures can be optimized by determination of column constants for temperature and solvent dependence.     

Purification of glycerol/water solutions from biodiesel synthesis by ion exchange: sodium removal Part I

BACKGROUND: In this study, equilibrium and kinetic data of the ion exchange of sodium from glycerol–water mixtures on the strong acid resin Amberlite‐252 were obtained. Basic parameters for the design of ion exchange units for the purification of the crude glycerol phase from biodiesel production have been determined. RESULTS: Equilibrium uptake of sodium ions with the strong acid ion exchanger Amberlite‐252 was studied at three temperatures. The Langmuir equation and the mass action law model were used to fit the experimental equilibrium data. Equilibrium constants and thermodynamic parameters were obtained at each temperature. Kinetic experiments were carried out to evaluate the effective diffusion coefficients of sodium on the resin Amberlite‐252 in glycerine–water media. CONCLUSIONS: Equilibrium results indicate that this process is favourable and also that its selectivity decreases with temperature increase from 303 to 333 K. Both models were able to fit the experimental equilibrium data. Kinetic experiments showed that the rate of mass transfer in this binary system is high. An Arrhenius type equation allowed the correlation of effective diffusion coefficients and temperature. The results indicate that the macroporous resin Amberlite‐252 could be useful for removal of sodium ions from glycerine/water solutions with a high salt concentration. Copyright © 2008 Society of Chemical Industry     

两性淀粉的取代度与吸湿保湿性能关系的研究

以淀粉为母体，3-氯-2-羟丙基三甲基氯化铵和氯乙酸为改性剂，通过清洁的半干法工艺合成出不同羧甲基取代度高的水溶性两性淀粉，并对其吸湿、保湿性能进行研究。结果表明，两性淀粉的吸湿、保湿性能均随着羧甲基取代度的增加而增强。当RH为81％，阴离子取代度大于0．08时，两性淀粉的吸湿性与甘油相当，而保湿性在RH81％和RH38％下均优于甘油；两性淀粉的吸湿速率随着羧甲基阴离子含量增加而提高。初步探讨了两性淀粉的吸湿动力学，水分子在两性淀粉中的扩散属于non-Fickian类型。     

Study on Industrial Scale Chromatographic Separation Methods of Galactose from Biomass Hydrolysates

Galactose is an aldohexose, which has commercial uses in the pharmaceutical and food industries. Since monomeric galactose is not a freely occurring compound, it must be produced from galactose‐containing hydrolysates. This paper reports the results of experimental studies of the chromatographic separation of galactose in aqueous solutions by ion exchange resins on an industrial scale. Until now, galactose has only been determined from various solutions by liquid chromatography (HPLC) on an analytical scale. Chromatographic separation of galactose from carbohydrate mixtures was studied with strong acid cation exchange resins in Na⁺, Ca²⁺ forms and strong base anion exchange resin in SO₄^2– form. The feed solutions were hydrolysates from three possible galactose sources: lactose, gum arabic and hemicellulose in spent sulfite liquor. The main monosaccharide impurities in these raw materials were glucose, arabinose, and xylose. It was demonstrated that large scale liquid chromatography can be used effectively for galactose separation from complex carbohydrate mixtures such as plant hydrolysates as well as lactose hydrolysate.     

Formation of formic acid from glycerine using a hydrothermal reaction

BACKGROUND: Glycerine, a main by‐product of the biodiesel manufacturing process, has potential to be an important biorefinery feedstock with the rapid increase in biodiesel production all over the world. Hydrothermal experiments with glycerine were carried out at 250 °C using H₂O₂ as an oxidant. RESULTS: Glycerine was converted into formic acid with a yield of 31.0% based on the starting mass of carbon in glycerine. A possible oxidation pathway for the formation of formic acid from glycerine is proposed. In the proposed pathway, glycerine may first be oxidised and then decomposed into formic acid and oxalic acid. Oxalic acid was indirectly attributed to the increase of formic acid production from glycerine, but it instead acts as a retardant to prevent further oxidation of formic acid. However, when an alkali was added to the experimental conditions, the yield of formic acid was not greatly improved, reaching only 34.7%. CONCLUSION: The present work should help to facilitate further studies to develop a new green process for the production of formic acid from renewable biomass. © 2012 Society of Chemical Industry     

生物柴油生产过程中粗甘油的预处理

对生物柴油生产过程中粗甘油进行真空脱醇、酸化、稀释、中和等过程处理,达到工业甘油生产的质量要求。在真空度-0.07～-0.08 MPa下,温度80℃加热1 h,粗甘油甲醇含量降至0.4%以下;用50%硫酸酸化至pH 4,粗甘油体积百分数为61%;在50 g粗甘油中加入15 mL水稀释,生物柴油与甘油分离较好。经处理后甘油水经真空精馏、脱臭、脱色达到工业甘油标准。     

甘油作陶瓷磨具成型料松散度调节剂的研究

本文针对固结陶瓷磨具生产中存在的成型料结块现象及机理加以分析。在参考大量文献的基础上选定甘油作为成型料松散度调节剂,对加入甘油后成型料的松散性、流动性进行研究,检测成型料压制出的湿、干坯强度,并对试验产品的各项性能进行分析对比。结果显示成型料添加甘油2-4ml／kg干料后,成型料的松散性、流动性提高50％以上。在生产应用中发现,采用成型料添加甘油的新工艺后,年度组织不均废品率由原来的5．40％降到2．00％左右;年度总废品率由8．87％降到4．00％左右。     

Hybrid separation processes combining vacuum distillation with fractional crystallization,partial melting,and granulation

The physicochemical fundamentals of the combined processes of distillative crystallization (also called distillation crystallization or distillative freezing) and distillative sweating (also called distillation sweating or distillation melting) are considered. Results of the experimental study of the kinetics of separation of binary and ternary organic mixtures of various forms (liquids, powders, continuous layers, and granules) are presented. The high efficiency of the combined processes that make it possible to rapidly decrease the impurity content by one to two orders of magnitude after a single stage is shown. It is found that these processes can be used for effective separation of the mixtures of a eutectic composition when conventional crystallization is not applicable. Dependences of the important kinetic characteristic—an effective diffusion coefficient—on pressure are determined for a number of mixtures. An empirical formula for estimating its values is proposed. It is found that the kinetic features of the combined processes conducted under nonequilibrium conditions can cause both a decrease and an increase in the efficiency of separation of the mixtures of different types in comparison with calculated values for the equilibrium process. A method is developed that makes it possible to combine distillative crystallization with the granulation of a melt in a semicontinuous or continuous process on a cooled movable belt. The method ensures the additional purification of solidifying granules from volatile impurities. Results of calculating the main characteristics of the combined process for purifying naphthalene granules in the batch and continuous modes are given.     

Separation of CO2/CH4 mixtures with the MIL-53(Al) metal–organic framework

Adsorptive separation of CH₄/CO₂ mixtures was studied using a fixed-bed packed with MIL-53(Al) MOF pellets. Such pellets of MIL-53(Al) were produced using a polyvinyl alcohol binder. As revealed by N₂ adsorption isotherms, the use of polyvinyl alcohol as binder results in a loss in overall capacity of 32%. Separations of binary mixtures in breakthrough experiments were successfully performed at pressures varying between 1 and 8 bar and different mixture compositions. The binary adsorption isotherms reveal a preferential adsorption of CO₂ compared to CH₄ over the whole pressure and concentration range. The separation selectivity was affected by total pressure; below 5 bar, a constant selectivity, with an average separation factor of about 7 was observed. Above 5 bar, the average separation factor decreases to about 4. The adsorption selectivity is affected by breathing of the framework and specific interaction of CO₂ with framework hydroxyl groups. CO₂ desorption can be realised by mild thermal treatment.     

Vapour permeation of VOC emitted from petroleum activities: Application for low concentrations

This study deals with the application of vapour permeation on the abatement of air polluted with VOC, from low to medium concentrations. Toluene, butadiene and propylene were chosen as model compounds. On a first part of the study, the permeation of single VOC, binary and ternary VOC/air mixtures was performed at different flow rates and VOC concentrations. The permeate flux, permeance, enrichment factor, separation efficiency and the recovery were determined. The experimental results were compared to those obtained with a mathematical model, allowing the calculation of the membrane area required to eliminate 95% of the feed VOC content.     

液相物性对壳侧不互溶双组分两相流截面含气率及两相压降的影响

在用空气-水、空气-0号柴油研究的基础上,用空气和质量浓度为30％的甘油水溶液研究了理想管壳式换热器壳侧平均截面含气率和两相压降,以期进一步考察不同液相物性的影响.研究表明,液相物性对两者均有一定影响.提出了不同液相物性时截面含气率的通用关联式.根据流型整理了两相摩擦因子.并提出了一种新的两相摩擦压降关联式,它能较好地预测不同液相物性时两相压降的实验数据.     

DISTILLATION UNDER ELECTRIC FIELDS

ABSTRACT

Distillation is the most common separation process used in the chemical and petroleum industry. Major limitations in the applicability and efficiency of distillation come from thermodynamic equilibria, that is, vapor-liquid equilibria (VLE), and heat and mass transfer rates. In this work, electric fields are used to manipulate the VLE of mixtures. VLE experiments are performed for various binary mixtures in the presence of electric fields on the order of a few kilovolts per centimeter. The results show that the VLE of some binary mixtures is changed by electric fields, with changes in the separation factor as high as 10% being observed. Batch distillation experiments are also carried out for binary mixtures of 2-propanol and water with and without an applied electric field. Results show enhanced distillation rates and separation efficiency in the presence of an electric field but decreased separation enhancement when the electric current is increased. The latter phenomenon is caused by the formation at the surface of the liquid mixture of microdroplets that are entrained by the vapor. These observations suggest that there should be an electric field strength for each system for which the separation enhancement is maximum.

     

生物乙醇提浓工艺中渗透蒸发膜材料的研究进展

渗透蒸发膜分离技术具有分离效率高、低能耗、易于和发酵装置耦合等优势,在生物乙醇的分离、提浓工艺中得到广泛应用。结合国内外生物乙醇的研究现状,综述了渗透蒸发膜分离技术的研究进展,并对渗透蒸发膜分离技术的核心材料--膜材料的制备与应用进行详细介绍,展望了生物乙醇的渗透蒸发膜分离技术的发展前景。