Solvent efficiency for oil extraction from spent bleaching clay

Various alcohols and hydrocarbons were used as solvents to extract the residual oil in spent bleaching clay from palm oil refining. The content of oil and minor components in the spent clay was >40% by weight. The efficiencies of extraction by the polar alcohols, except for methanol, were higher but with a slower initial rate than the nonpolar hydrocarbons. The free fatty acids contents, the Totox values (anisidine value+2 x peroxide value), and the color of the alcohol-extracted oil were also higher than that by the hydrocarbons resulting in poorer quality oils. All the extracted oils, irrespective of the solvent used, have poorer quality than crude palm oil. However, for regeneration of the residual spent clay, the polar alcohols should be more suitable as more of the impurities are removed.     

以废白土为原料制备生物柴油及其资源化利用

生物柴油是一种清洁可再生能源,正受到越来越多的重视与关注。推动生物柴油技术产业化应用的关键是降低生产成本。廉价原料、高效催化剂、新工艺与设备等是解决问题的重要途径,而发展廉价原料应是首选。油脂厂产生的废白土含油量高达20%~40%,若将其回收用以制备生物柴油既是廉价原料也可实现废弃物的资源化利用。本文综述了以废白土为原料制备生物柴油的研究进展,主要包括一步法和两步法工艺。两步法较为成熟,但工艺复杂,溶剂用量大。一步法流程简单,成本较低,但反应时间长,催化剂分离困难。因此,未来须着力于在一步法工艺基础上,探索快速、高效且催化剂易于回收的反应工艺。     

Factors affecting the pyrophorisity of spent bleaching clay

Artificial cakes of bleaching clay/vegetable oil have been studied for their pyrophoric character using both Differential Scanning Calorimetry and a constant-temperature, fixed-interval, spontaneous heating (CaTFISH) test developed in this laboratory. It was determined that this is a two-step process involving a first-stage low-temperature spontaneous heating reaaction followed by a second-stage high-temperature spontaneous heating reaction. The latter is characterized by charring and, in some cases, flaming combustion. A study of relevant variables has established that clay type, filter cake age, oil retention, moisture, and the presence of antioxidant significantly affect the spontaneous heating characteristics of clay/oil masses. Oil type was not found to be a significant variable in these studies.     

Al-Pillared clay for cottonseed oil bleaching: An optimization study

In this study, Al-pillared white bentonite (Ordu-Unye, Turkey) was used for cottonseed oil bleaching. Pillaring process parameters were optimized in terms of bleaching efficiency as the bleaching capacity of cottonseed oil. The initial cation concentration, hydrolyzing agent ratio, and thermal treatment temperature were chosen as major process parameters. Pillared clays were characterized by FTIR and differential thermal analysis. The bleaching efficiency of bentonite increased from 11.8 to 17.5% by acid activation and to 33.5% by further Al pillaring. The optimal pillaring process conditions for cottonseed bleaching were an initial concentration of AICl₃, of 0.5 M, a OH⁻/Al³⁺ molar ratio of 0.3, and a thermal treatment temperature of 700°C.     

Adsorption of chromium(VI) and nickel(II) ions on acid- and heat-activated deoiled spent bleaching clay

De-oiled spent bleaching clay was activated either by acid treatment followed by heat activation or by heat activation alone at temperatures between 200 and 800°C. The surface area of the heat-activated clay attained a maximal value of ≈120 m² g⁻¹ at temperatures between 400 and 500°C while the acid-heat-treated clay attained maximal surface area of ≈140 m² g⁻¹. The adsorption capacities of chromium [Cr(VI)] for both series studied increased as the activation temperature increased until 300°C and decreased again at higher temperatures. At lower pH, more than 95% of the Cr(VI) was absorbed in a solution with initial concentration of 1 mg L⁻¹ per gram of adsorbent activated at 300°C. The adsorption patterns followed Freudlich's isotherms. Two maximal values of adsorption capacities of nickel [Ni(II)] were observed at activation temperatures of 200 and 500°C for acid-treated samples, whereas these were at 200 and 700°C for the nonacid-treated samples. The amount of Ni(II) adsorbed increased with the pH of the solution for all samples studied. The maximal adsorption capacities of the adsorbents in solution containing initial Ni(II) concentration of 5 mg L⁻¹ per 0.5 g of adsorbent and at pH 6 were found to be 44 and 42%, respectively, for the acid-treated sample activated at 500°C and for the nonacid-treated sample activated at 700°C. They all obeyed both the Langmuir's and Freundlich's isotherms.     

Decolorisation of crude palm oil by acid-activated spent bleaching earth

Regeneration of spent bleaching earth by acid activation and heat treatment has been investigated. Spent bleaching earth was activated by H₂SO₄ of various concentrations (1–40%) and heat treated at 120°C–350°C. The experimental results indicate that treatment of spent bleaching earth with 10% H₂SO₄ at 350°C produced a material which was most effective in removing coloured pigments from crude palm oil. Subsequent experiments were conducted using this particular acid-treated spent bleaching earth. Various parameters which affect the sorption process were studied. They include initial crude palm oil concentration, sorbent dosage and temperature. Applicability of both the Freundlich and Langmuir isotherms to the acid-treated spent bleaching earth–palm oil hexane miscella system indicates that both physiosorption and chemisorption were involved in the sorption process. Measurements of various quality parameters of bleached and crude palm oils were carried out. They include Lovibond Colour index, carotene content, peroxide value, free fatty acid, fatty acid composition and iodine value. The results show that the bleached palm oil retained good oil quality after the decolorisation process using 10% acid-treated spent bleaching earth with a Lovibond Colour of 6·4. © 1998 SCI     

Statistical design of experiments of acid activation of smectite clay from Serbia and its bleaching capacity

BACKGROUND: Serbian smectite clay has been activated using a response surface method with central composite design. Because, among the criteria of an edible oil, colour is the most important factor in the commercial value of the oil, and since the colour is due to the presence of pigments such as β‐carotene in the crude oil, acid‐activated clay was used for decolourisation of soybean oil. RESULTS: The effects of five parameters, namely, temperature, time, acid strength, solid/liquid ratio and stirring speed, on the process of acid activation of the clay and its bleaching capacity were determined using a statistical model. The results indicated that all parameters were significant factors in the bleaching capacity of acid‐activated clay, and a quadratic polynomial equation for bleaching capacity was obtained by multiple regression analysis. The optimal bleaching capacity was estimated to be 96.61% for an experimental run under the following conditions: activation temperature 80 °C, HCl concentration 4.78 mol L^?1, stirring speed 450 rpm, solid/liquid ratio 1:4.5 and activation time 2.81 h. CONCLUSIONS: The central composite design, regression analysis and response surface method were effective in identifying the optimal conditions for bleaching capacity of acid‐activated smectite. Copyright © 2008 Society of Chemical Industry     

溶剂萃取法修复石油污染土壤

对溶剂萃取法修复石油类污染土壤的新技术做了较为全面的概述.首先,介绍了溶剂萃取技术的概念、机理和适用范围;其次,介绍了包括有机溶剂、表面活性剂、环糊精、超临界流体在内的萃取剂的研究进展;再次,阐述了影响溶剂萃取效率的因素和溶剂萃取的工艺条件;最后,对溶剂萃取技术的研究和应用做了展望.     

Distribution of clay minerals in the process streams produced by the extraction of bitumen from Athabasca oil sands

This study investigates the affinity of clay minerals in oil sands for the water‐continuous tailings and hydrocarbon‐continuous froth streams produced from the extraction of bitumen from oil sands. Clay minerals in oil sands processing impact bitumen flotation in separation vessels, emulsion formation during froth treatment, and fine tailings behaviour. X‐ray diffraction of oriented clay slides and random powder samples were used to quantify the clay minerals in the oil sands ore and process streams. Particle size distribution and clay activity balances were also conducted around the extraction process. The degree of partitioning during the conditioning and flotation stages in a batch extractor was determined by the surface properties of the clay minerals present. The water‐continuous tailings stream was further separated into fine and coarse tailings fractions through sedimentation. The bulk of the clay minerals reported to the fine tailings stream. Illite and mixed layered illite‐smectite partitioned less to the hydrocarbon‐continuous froth than kaolinite. Also, the illite‐smectite in the froth stream appeared to be different from the illite‐smectite in the water continuous streams.     

超临界CO2萃取含油污泥研究现状与进展

含油污泥是一种含有大量有机物、絮状体的复杂多相稳定乳化胶体体系,主要来源于油气开采和集输过程。污泥中的含油量一般为10%~30%（体积分数）,利用超临界二氧化碳（supercritical CO₂,scCO₂）提取和回收其中的油基成分可实现污泥的无害化处理,并产生可观的经济效益。本文综述了scCO₂萃取原理及工业化应用情况,分析了萃取条件及携带剂对萃取率的影响,重点论述了scCO₂萃取含油污泥的相平衡热力学及动力学机制研究进展。指出应坚持实验与理论相结合的手段,着重开展以下三方面的研究：①针对含油污泥组成复杂、极性组分含量高的特点,结合scCO₂与含油污泥多组分复杂体系相平衡实验,建立scCO₂萃取含油污泥的相平衡模型,阐明scCO₂萃取含油污泥的相平衡特征及影响因素;②考虑不同分子间的键结合能与非键结合能,从scCO₂萃取油基的微观效应出发,探究油基与污泥基质间的吸附、解吸及扩散规律,定性描述、定量揭示scCO₂萃取油的动力学特征与作用机制;③考虑萃取工艺的经济性,以萃取率最高为目标函数,建立萃取条件优化模型,为scCO₂萃取含油污泥工艺的设计、优化及工业化应用提供理论与技术支撑。     

超临界CO2萃取丁香油的数值模拟

为了预测超临界CO₂萃取挥发油动态过程,根据挥发油在超临界CO₂与物料之间的质量传递平衡,采用集总参数法建立超临界CO₂萃取丁香油过程的数学模型。结合不同温度、压力、粒径和CO₂流速条件下的实验结果,对方程进行了合理的简化,并利用实验数据拟合出模型中CO₂密度、粒径和流速的系数。验证结果表明模型的计算值和实验值的平均相对误差在6. 88%～57. 78%之间,建立的数值模型能较好地描述实际的超临界CO₂萃取丁香油行为。     

超临界CO_2流体萃取植物油的实验研究

建立了一套超临界流体萃取实验装置,就大豆和花生两种植物油超临界流体萃取进行了较为详细的实验研究.在探讨了压力、温度、颗粒度、空隙率以及时间等对萃取率的影响之后,获得了指导实际生产的最佳工艺参数条件.     

超临界CO_2萃取青皮挥发油的工艺研究

采用正交实验法对超临界CO2萃取中药青皮挥发油的最佳工艺条件进行优选。以挥发油得率为考察指标,探讨了萃取压力、萃取温度、萃取时间三因素在不同水平下对青皮挥发油得率的影响,并与水蒸气蒸馏法进行了比较。研究表明,萃取压力对挥发油得率有显著影响,萃取温度及时间影响不显著,各因素作用主次关系为:压力>温度>时间。优选得到的最佳工艺为:萃取压力25 MPa,萃取温度35℃,萃取时间1.5 h,得率为1.3197%,比水蒸气蒸馏法提高2.4倍,时间减少78.57%。超临界CO2萃取收率高、耗时短、品质好。     

超临界萃取法制备辣椒红色素

将原料干红辣椒采用溶剂法提取出辣椒树脂中间产品,并以其为原料进行了超临界CO2制备辣椒红色素的实验研究。通过对超临界萃取压力、温度、时间与装料系数的相关实验研究,确定出超临界CO2萃取法制备辣椒红色素的工艺条件。研究结果表明,最优工艺参数为:萃取压力20 MPa,萃取温度35℃,萃取时间6 h,装料系数0.7。制取的辣椒红色素产品符合中国国家标准,主要指标色价、己烷残留等均优于国标要求。     

A hydrodynamic model of a continuous supercritical fluid extraction system for the treatment of oil contaminated solids

Supercritical fluid extraction (SFE) has the potential to recover compounds from a range of solid matrices if a fully continuous process can be commercialized. This paper presents the development of a hydrodynamic model for a continuous pilot scale SFE process, involving countercurrent flow of a slurry and a supercritical fluid. The model developed is based on first principles and focuses on predicting pressure and slurry level within the extraction vessel. The model was validated using pilot scale system data. Using adjusted parameters, the model accurately predicted steady state pressure and provided a good estimate of slurry level.     

超临界二氧化碳萃取器萃取分离香茅油

本文介绍了利用现有１５０Ｌ高压釜（压力２０ＭＰａ）改造的超临界二氧化碳萃取器萃取分离香茅油,探讨了压力、温度、时间对萃取分离效果的影响。结果表明,采用超临界二氧化碳萃取器萃取分离香茅油时应选择一个适宜的压力、温度和萃取时间,产品的色、香味、纯度均优于常规的减压蒸馏法。     

Supercritical fluid extraction of oil from millet bran

Proso millet bran [Panicum miliaceum (L.)], variety Dakota White, was extracted with supercritical carbon dioxide (SC-CO₂) to yield crude oil. The effects of operating parameters (pressure, temperature, and specific solvent flow) and of features of the raw material (moisture content and particle size) on oil extraction were investigated. Complete de-oiling of ground millet bran pellets was achieved under 300 bar at 40°C with a specific solvent flow of 2–10 h⁻¹ within 200 to 500 min. Solvent requirements were 20–30 kg CO₂/kg raw material. Composition of crude SC-CO₂ oil extracted under optimal conditions, i.e., fatty acid profile, amount of unsaponifiables, tocopherols, free fatty acids, sterols, sterol esters, waxes, hydrocarbons, and phospholipids, was compared to that of crude oil obtained by petroleum ether extraction. These two oils were similar in terms of fatty acid profile and amount of free fatty acids, unsaponifiables, peroxides, and tocopherols. They differed in respect to phospholipids (present in petroleum etherextracted oil and absent in SC-CO₂ extracted oil), metals, and waxes (lower levels in SC-CO₂ extracted oil). The effects of extraction procedures on oxidative stability of crude SC-CO₂ oil were studied. Ensuring that all pieces of the extractor in contact with the oil were in stainless steel; cleaning the separator, i.e., washing with KOH, rinsing, purging with N₂ and CO₂, and heating; performing a couple of extractions before the main extraction; and achieving the extraction without interruption all positively influenced the oxidative stability of the oil. Conversely, increasing CO₂ purity above 99.5% had no effect. Oxidative stability of the SC-CO₂ oil extracted under these conditions was only slightly lower than that of the oil extracted with petroleum ether.     

Supercritical CO2 extraction of essential oils and cuticular waxes from peppermint leaves

Essential oils and cuticular waxes were extracted from peppermint leaves with supercritical carbon dioxide in a semicontinuous-flow extractor. The effects of CO₂ flow rate and pressure on the extraction rate were studied within the flow rate range of (4·1–9·8) × 10⁻⁵ kg s⁻¹ and the pressure range of 10–30 MPa. Flow rate effect indicated that the intraparticle diffusion resistance was not dominant in this process. The extraction rate of cuticular waxes increased remarkably with the pressure, whereas that of essential oils was almost constant as compared with cuticular waxes. The concentration of cuticular waxes at the exit of the extractor was close to the solubility of triacontane while that of essential oils was much lower than the solubility of 1-menthol.     

Utilization of waste activated bleaching earth containing palm oil in riboflavin production by <Emphasis Type="Italic">Ashbya gossypii</Emphasis>

Waste activated bleaching earth (ABE) discharged by an oil refinery plant, which contained 40% palm oil, was used for riboflavin production by a culture of the filamentous fungus Ashbya gossypii. When 188 g/L waste ABE containing 75 g/L palm oil was added to the culture, 80% of the palm oil was consumed after 4 d, and the riboflavin concentration reached 2.1 g/L after 10 d of culture. This concentration was almost 1.5 times higher than for cultures grown on pure palm oil, in which case only 68% of the palm oil was consumed. Before the culture was initiated, the surface of the waste ABE was smooth and resembled clay that was covered with palm oil. After the culture, the oil content decreased to 8%. The black color of waste ABE gradually faded and turned yellow, with the ABE finally forming a yellow powder. Eighty percent of the riboflavin produced during the culture period was transferred to oil-depleted waste ABE and the waste-oil-depleted ABE had 14 mg of riboflavin/g of oil-depleted waste ABE. The waste ABE containing waste palm oil was suitable for use as a raw material for the production of value-added riboflavin. Thus, this research might provide a good model for the reuse of waste resources containing vegetable oil.     

Supercritical carbon dioxide extraction in membrane formation by thermally induced phase separation

In this study, a novel and environmentally friendly extracting method, supercritical carbon dioxide (SC‐CO₂) extraction, was investigated in the thermally induced phase separation (TIPS) process for making microporous membranes. In the SC‐CO₂ extraction, the effects of extraction time, pressure, and temperature on the extraction fraction, membrane morphology, and membrane performance were investigated. It was concluded that with extraction conditions of 18 MPa, 35°C and 2 h, the porous membrane had the highest extraction fraction. There was a close relationship between membrane performance and the extraction conditions of SC‐CO₂, and it is possible to tailor membrane performance through the choice of extraction conditions. Compared with traditional solvent extraction, a dry membrane treated by SC‐CO₂ extraction has much less shrinkage and greater water permeability, whereas the degree of crystallization of a membrane extracted by SC‐CO₂ is slightly greater than that extracted by ethanol. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1632–1639, 2007