Alternative hydrocarbon solvents for cottonseed extraction: Plant trials

Hexane has been used for decades to extract oil from cottonseed and is still the solvent of choice for the edible-oil industry. Due to increased regulations as a result of the 1990 Clean Air Act and potential health risks, the edible-oil extraction industry urgently needs an alternate hydrocarbon solvent to replace hexane. Based on laboratory-scale extraction tests, two hydrocarbon solvents, heptane and isohexane, were recommended as potential replacements for hexane. A cottonseed processing mill with a 270 MT/day (300 tons/day) capacity agreed to test both solvents with their expander-solvent process. Extraction efficiencies of isohexane and heptane, judged by extraction time and residual oil in meal, refined and bleached color of miscella refined oil, and solvent loss, were comparable to that of hexane. However, fewer problems were encountered with the lower-boiling isohexane than with the higher-boiling heptane. With isohexane, the daily throughput increased more than 20%, and natural gas consumption decreased more than 40% as compared to hexane.     

Adsorptive gossypol removal

Gossypol is extractable from cottonseed by using aqueous ethanol. The equilibrium between undissolved gossypol in cottonseed and that dissolved in the solvent determines the residual gossypol. To move the equilibrium toward extraction from the seeds, the dissolved gossypol needs to be removed from the gossypol-solvent-oil mixture. Gossypol removal from the mixture by adsorption on alumina, silica and molecular sieve 5Å was tested. Experimental results indicated that gossypol was more selectively adsorbed than triglycerides by these adsorbents. Alumina and silica had higher gossypol adsorption capacities than molecular sieve 5Å.     

Alternative hydrocarbon solvents for cottonseed extraction

Hexane has been used for decades to extract edible oil from cottonseed. However, due to increased regulations affecting hexane because of the 1990 Clean Air Act and potential health risks, the oil-extraction industry urgently needs alternative hydrocarbon solvents to replace hexane. Five solvents,n-heptane, isohexane, neohexane, cyclohexane, and cylopentane, were compared with commercial hexane using a benchscale extractor. The extractions were done with a solvent to cottonseed flake ratio of 5.5 to 1 (w/w) and a miscella recycle flow rate of 36 mL/min/sq cm (9 gal/min/sq ft) at a temperature of 10 to 45°C below the boiling point of the solvent. After a 10-min single-stage extraction, commercial hexane removed 100% of the oil from the flakes at 55°C; heptane extracted 100% at 75°C and 95.9% at 55°C; isohexane extracted 93.1% at 45°C; while cyclopentane, cyclohexane, and neohexane removed 93.3, 89.4, and 89.6% at 35, 55, and 35°C, respectively. Each solvent removed gossypol from cottonseed flakes at a different rate, with cyclopentane being most and neohexane least effective. Based on the bench-scale extraction results and the availability of these candidate solvents, heptane and isohexane are the alternative hydrocarbon solvents most likely to replace hexane. Presented in part at the AOCS Annual Meeting & Expo, Atlanta, Georgia, May 1994.     

Ethanol extraction of oil,gossypol and aflatoxin from cottonseed

Commercial processing of cottonseed requires hexane to extract and recover edible oil. Gossypol and aflatoxin are not removed from extracted meals. A bench-top extraction process with 95% (vol/vol) aqueous ethanol (EtOH) solvent has been developed that extracts all three of the above materials with a much less volatile solvent. In this process, cottonseed is pretreated and extracted with ambient 95% EtOH to remove gossypol and then extracted with hot 95% EtOH to extract oil and aflatoxin. Membranes and adsorption columns are used to purify the various extract streams, so that they can be recycled directly. A representative extracted meal contained a total gossypol content of 0.47% (a 70% reduction) and 3 ppb aflatoxin (a 95% reduction). Residual oil content was approximately 2%. Although the process is technically feasible, it is presently not economical unless a mill has a continual, serious aflatoxin contamination problem. However, if a plant cannot meet the hexane emission standards under the Clean Air Act of 1990, this process could provide a safer solvent that may expand the use and increase the value of cottonseed meal as a feed for nonruminants. Presented in part at the AOCS annual meeting, Toronto, Canada, May 1992.     

丙酮、己烷与水混合溶剂脱除棉酚的实验研究

用混合溶剂(丙酮、己烷和水)浸出冷榨棉饼进行提油和脱酚,其较适合的工艺条件是:浸出温度47℃,丙酮、己烷和水的溶剂配比为50∶50∶6(A∶H∶W,V∶V∶V),溶剂与饼的比值为5∶1(mL/g),浸出时间150min。在此条件下可使棉粕中残留的游离棉酚<0 060%,总棉酚<0 80%,残油率<1 0%,同时副产粗棉酚。     

Supercritical carbon dioxide extraction of cottonseed with co-solvents

Extraction of cottonseed lipids with supercritical carbon dioxide (SC-CO₂) was conducted with and without a cosolvent, ethanol or 2-propanol (IPA). At 7000 psi and 80°C, the reduced pressure, temperature and density of SC-CO₂ was at 6.5, 1.17 and 1.85, respectively; the specific gravity was 0.87. Under these conditions, CO₂ is denser than most liquid extraction agents such as hexane, ethanol and IPA. The extraction of cottonseed with SC-CO₂ gave a yield of more than 30% (moisture-free basis). This is comparable to yields obtained by the more commonly used solvent, hexane. The crude cottonseed oil extracted by SC-CO₂ was visually lighter than refined cottonseed oil. This was substantiated by colorimetric measurements. No gossypol was detected in the crude oil. However, crude oil extracted by SC-CO₂, to which less than 5% of ethanol or IPA as co-solvent was added, containedca. 200 ppm of gossypol, resulting in the typical dark color of cottonseed crude oil with gossypol. CO₂ extracted a small amount of cottonseed phosphatides, about one-third of that extracted by pure ethanol, IPA or hexane. A second extraction with 100% ethanol or IPA after the initial SC-CO₂ extraction produced a water-soluble lipid fraction that contained a significant amount of gossypol, ranging between 1500 and 5000 ppm. Because pure gossypol is practically insoluble in water, this fraction is believed to be made up of gossypol complexed with polysaccharides and phosphatides. Partially presented at the AOCS 1993 Annual Meeting & Expo in Anaheim, California.     

热碱法脱除游离棉酚的实验研究

介绍了用热碱法对棉籽粕进行脱酚的工艺原理,并对棉籽粕进行了脱酚实验研究。通过正交试验,热碱法脱酚的最适合条件为pH值8～9,温度60℃,时间3h,最终棉籽蛋白液棉酚含量为12×10-6,完全低于联合国咨询委员会规定的食用棉籽蛋白质中游离棉酚含量≤0.06%标准。     

Competitive adsorption among sesame oil components in a concentrated miscella system

Competitive adsorption of free fatty acids and carotenoids adsorption from sesame oil miscellas on vegetable carbon was studied by regression analysis. The equations obtained indicated that unsaturated carbonyls, free fatty acids (FFA₀), and carotenoids interacted to determine fatty acid and carotenoid adsorption. The driving force for carotenoid adsorption, the carotenoid concentration (C₀), was affected by a quadratic function of free fatty acid concentration [i.e., (FFA₀/C₀)²]. As FFA₀/C₀ increased, carotenoid adsorption efficiency was reduced, possibly because the accessible adsorption sites for carotenoids were occupied by fatty acids. Unsaturated carbonyls promoted free fatty acid adsorption, probably in the pores that were readily accessible for fatty acids. However, when the carbonyl concentration increased in the oil miscella, carbonyls were adsorbed instead of fatty acids. The results indicated how different oil molecules interact and affect adsorption (i.e., free fatty acids and carotenoids). Therefore, the adsorption process of vegetable oils (i.e., bleaching) has to be considered a multicomponent adsorption system.     

Acidic ethanol extraction of cottonseed

Ethanol (EtOH) is being evaluated as an alternate solvent to hexane for the extraction of glanded cottonseed. Hot EtOH, needed for efficient oil and aflatoxin extraction, binds gossypol to protein. However, this binding can be minimized by acidifying aqueous EtOH with a tribasic acid, such as phosphoric or citric. While this solvent extracts oil and gossypol, it does not affect EtOH’s ability to extract aflatoxin. The defatted cottonseed meals produced from this process contained 0.03% total gossypol (which is lower than meal prepared by most other processes) and the aflatoxin content was reduced from 69 to 2.9 ppb. These are preliminary results and additional research is needed to determine commercial feasibility. The removal of essentially all gossypol from an extracted meal has the potential to expand the use of cottonseed meal as a feed, increasing its value to both the cotton farmer and the seed processor. Presented in part at the 40th Oilseed Processing Clinic, March 4, 1991, New Orleans, LA.     

Adsorptive removal of aflatoxins

Physical removal of aflatoxins from cottonseed by solvent extraction with ethanol or isopropyl alcohol is technically feasible. These solvents used in the removal process are recycled to extraction systems after regeneration by distillation. However, distillation is costly due to high latent heat of the solvents. Adsorption techniques have been explored as a method to remove aflatoxins from these solvents. Enzyme-linked immunosorbent assays method and a high-performance liquid chromatography method with fluorescence detector were used to determine the toxins in the feed and eluates from the adsorption columns. Experimental data indicate that montmorillonite is highly effective for adsorptive aflatoxin removal. Adsorption data with neutral alumina and silica are also presented. Ethanol and ethanol-based miscellas, obtained from alcoholic cottonseed extractions were spiked with aflatoxins for this investigation. Presented in part at the 1991 AOCS Annual Meeting, Chicago, Illinois.     

脱硫吸附剂与吸附脱硫技术

综述了国内外原料气和燃料油吸附脱硫技术在吸附脱硫材料和吸附脱硫工艺方面的研究与开发进展。介绍了分子筛类、金属氧化物类、活性炭类等脱硫吸附剂。分别评述了物理吸附、活化吸附、选择性吸附等燃料油吸附脱硫技术的机理和工艺。     

用乙醇-水从双液相棉粕中提取棉子糖的研究

用双液相萃取工艺处理后的棉籽粕为原料,乙醇-水溶液为溶剂进行了棉子糖的提取试验,并考察了影响浸出率的因素。在单因素实验的基础上,通过正交实验得出优化后的提取工艺条件为:乙醇体积分数为70%,提取温度60℃,提取时间150 m in,物料溶剂比1∶14(即每克物料需14 mL溶剂)。在此工艺条件下,棉子糖的浸出率为92.5%。     

Effect of adsorption and solvent extraction process on the percentage of carotene extracted from crude palm oil

Palm carotene was successfully concentrated from crude palm oil (CPO) by a batch adsorption process using a synthetic (polymer) adsorbent followed by solvent extraction. Carotene was concentrated to about 20,000 ppm, or about 33.3 times the original concentration in CPO. Carotene recovery varied from 16 to 74% depending on the process conditions. Adsorption times, isopropanol (IPA) extraction times, temperatures of adsorption and solvent extraction process, effect of agitation during IPA extraction process, and adsorbent lifespan were evaluated to determine their effects on the percentage of carotene extracted and carotene concentration. The minimum adsorption time required was 0.5 h. However, an adsorption time of 1.5 h gave a significantly higher carotene concentration than adsorption times of 0.5, 1.0, and 0.2 h. The IPA extraction time was determined based on the final carotene concentration desired. The suitable temperature for adsorption and solvent extraction process was 40°C. There was no significant difference in the percentage of carotene extracted and carotene concentration between the IPA extraction process with and without agitation.     

Comparison of different sorbents (inorganic and biological) for the removal of Pb2+ from aqueous solutions

In an attempt to evaluate the suitability of activated sludge for Pb²⁺ removal, a comparative study was carried out using several chemical adsorbents and three types of biomass. The order of Pb²⁺ removal capacities for chemical adsorbents was found to be: ion exchange resin > zeolite > granular activated carbon (GAC) > powdered activated carbon (PAC), while for biomass the order was Aureobasidium pullulans > Saccharomyces cerevisiae > activated sludge. Although Pb²⁺ removal capacity (mg Pb²⁺ g⁻¹) of the activated sludge (30.9) was lower than those of the ion exchange resin (167.7) and other pure cultures of A pullulans (170.4) and S cerevisiae (95.3), it was higher than those of other chemical adsorbents such as GAC (26.0), PAC (2.1), and zeolite (30.2). The initial Pb²⁺ removal rates for the chemical adsorbents were in the order of PAC > GAC > zeolite > ion exchange resin, while for the biomass samples it was A pullulans > activated sludge > S cerevisiae. The initial Pb²⁺ removal rate of activated sludge was higher than those of GAC, zeolite, ion exchange resin and S. cerevisiae cells. Therefore, it was concluded that activated sludge that has been used in a municipal wastewater facility can be effectively used in heavy metal removal processes, in situ. © 2000 Society of Chemical Industry     

Tannin-based adsorbents from green tea for removal of monoaromatic hydrocarbons in water: Preliminary investigations

In this study, we report the adsorption of benzene and toluene from water using rarely reported tannin adsorbents. Tannin gel and tannin powder were synthesized by adding formaldehyde to green tea extract, while iron nanoparticles were synthesized by the addition of FeSO₄?·?7H₂O. The surface morphology of the synthesized adsorbents was determined using SEM and FTIR prior to application to contaminated water. The results show up to 88% removal of benzene and toluene in a batch system after 30?min of reaction time, with a higher rate of removal of toluene compared to benzene. A low pH value of 2 had an adverse effect on the tannin gel, reducing the total adsorption of benzene to approx. 37.5%. On the other hand, iron nanoparticles were least affected by the pH with an adsorption of 62.9% for benzene and 83.3% for toluene.     

乙醇溶析结晶法由棉籽壳制备木糖

采用乙醇溶析结晶方法,以棉籽壳为原料,经一系列处理步骤,得到一种木糖晶体产品;对该晶体产品进行了红外光谱分析、熔程分析、环境扫描电镜分析、液相色谱分析和粒度分析。结果表明,该晶体产品与由玉米芯得到的木糖晶体具有类似的红外光谱曲线和熔程,但在晶形上,该晶体呈长棱形,而玉米芯木糖晶体呈方形;按本文优化的操作条件进行操作,结晶产品纯度为99.64%,收率为77.6%,中间粒度(M.S.)为151μm,变异系数(C.V.)为47%。表明乙醇溶析结晶是一种很有潜力的结晶方法。     

微波强化棉籽油制备生物柴油的研究

利用微波强化以棉籽油和甲醇为原料,KOH为催化剂制备生物柴油。考察醇油摩尔比、催化剂用量、反应时间和微波功率对酯交换反应的影响。结果表明,醇油摩尔比为9∶1,催化剂用量为1.0%,反应时间为3 min,微波功率360 W为最优反应条件。在此反应条件下生物柴油产率可达94%。与传统合成方法相比,该方法可缩短反应时间30~35 min。所得生物柴油主要质量指标达到我国和欧洲(EN14214)生物柴油质量标准,通过红外光谱分析表明,棉籽油生物柴油具有生物柴油所含的官能团。     

燃煤电厂吸附剂喷射脱汞技术的研究进展

燃煤汞污染已引起广泛关注。燃煤电厂控制汞排放最成熟可行的技术是烟道活性炭喷射技术,但该技术在我国燃煤电厂的广泛应用还存在较多的科学问题,因为活性炭对烟气汞的脱除是包含吸附、扩散、传质及化学反应在内的多元化过程,因此,针对燃煤电厂吸附剂喷射脱汞技术的研究已成为当前的热点课题。本文从吸附剂喷射脱汞技术原理、脱汞吸附剂的评价方法、汞吸附机理研究以及吸附剂喷射脱汞数学模型方面评述了燃煤电厂吸附剂喷射脱汞技术近些年取得的研究进展,并在此基础上提出了开发廉价高效、可再生的脱汞吸附剂,全面深入研究吸附剂的脱汞机理以及开发简单、精确的吸附剂喷射脱汞数学模型等后续研究方向,可为我国燃煤电厂吸附剂喷射脱汞技术的开发提供一定指导。     

碳材料吸附脱除二氧化硫性能的影响因素

选用了7种不同物理化学特性的碳材料,分别为活性炭-1 (比表面积1779m²/g)、活性炭-2 (比表面积970m²/g)、多孔纳米炭-1 (平均孔径14nm)、多孔纳米炭-2 (平均孔径85nm)、多孔纳米炭-3 (平均孔径4.7nm,掺氮)、多孔纳米炭-4 (平均孔径4.1nm,不掺氮)和纳米碳纤维。在对比这7种不同的碳材料的物理化学特性与其脱硫性能的基础上,研究材料的物理化学特性、脱硫温度、反应空速等因素对碳材料吸附脱除SO₂性能的影响。结果表明,碳材料吸附脱除SO₂的性能受材料的比表面积、孔隙结构、表面官能团、脱硫温度和反应空速的综合影响。不同的碳材料中,材料的孔隙结构和表面官能团对材料的脱硫性能影响很大,以微孔结构为主的碳材料SO₂去除率较高,以介孔结构为主的碳材料脱硫容量较高;随着脱硫温度升高,碳材料的吸附脱硫性能降低;随着反应空速降低,碳材料的吸附脱硫性能升高。本研究中,多孔纳米炭NCP-10的吸附脱除SO₂性能最好,能在室温下保持100%的...     

Montmorillonite-perlite-iron ceramic membranes for the adsorption/removal of As(III) and other constituents from surface water

In this study, ceramic membranes made of montmorillonite, perlite and iron were used to remove As(III) from water. Membranes prepared with 0.0, 0.5, 1.0, and 1.5 wt% of iron content were used to filtrate As(III) synthetic water and surface water solutions. As(III) adsorption capacity and removal efficiency, and other parameters such as cations and anions content, turbidity, pH, electrical conductivity were used to evaluate the membranes' performance. Results show that the As(III) adsorption/removal capacity of membranes was improved by the addition of iron. Adsorption capacity of 7.5 μg As(III)/g and removal efficiency of 97% can be achieved in membranes with 1.0 wt% of iron filings content for surface water; however, a greater amount of iron in the membrane structure limits the adsorption capacity of As(III). Besides the capacity of ceramic membranes to adsorb/remove As(III), membranes were also effective to remove other ions, turbidity, and electrical conductivity from the surface water. The addition of iron to the ceramic membranes enhanced their capacity to remove such surface water constituents. These results are important from the practical viewpoint showing the potential of ceramic membranes for the removal of metalloids and other water constituents. Langmuir isotherm model best described the adsorption process in ceramic membranes, suggesting that adsorption of As(III) happened on a monolayered surface of the ceramic membrane.