纳米磁酶水酶法在磁流化床中提取大豆油脂的数值模拟及应用

Numerical simulation and application of nano-magnetic enzyme hydroenzymatic method for soybean oil and grease extraction in a magneto-fluidized bed

为提高大豆油的提取率以及油的品质,该研究将游离纤维素酶固定在磁性高分子载体Fe_(3)O_(4)/SiOx-g-P(GMA)上,利用数值模拟确定磁流化床中水酶法提油的最佳参数,并将最佳参数应用在磁流化床中,通过单因素试验探究磁性固定化纤维素酶在磁流化床中水酶法提油的最佳工艺条件。结果表明:扫描电镜、粒径分析和红外光谱显示磁性固定化纤维素酶已固定在磁性高分子载体Fe_(3)O_(4)/SiOx-g-P(GMA)上,且具有较好的磁响应能力,与游离酶相比,磁性固定化纤维素酶提高了酶的耐热性和耐酸碱性。数值模拟得出磁场强度为0.034 T,流速为0.0041 m/s时,磁酶在磁流化床中可与大豆料液充分接触,有利于提高大豆油提取率。磁流化床中水酶法提油较优工艺为:酶添加量为1.2 mg/g,pH值为5,温度为55℃,反应时间120 min,此时大豆油提取率较优为90.3%。磁性固定化纤维素酶在磁流化床中可以连续使用12 h。该研究提高了大豆油提取率,与间歇反应相比,磁流化床大豆油提取率增加了6.1%。研究结果为后续磁流化床水酶法提油提供了理论依据。

Soybean oil has been one of the most consumed cooking oil extracted from the seeds of the soybean.Aqueous and enzymatic processes can be widely expected for edible oil extraction in recent years.In this study,a series of numerical simulations were carried out to determine the optimum parameters for the aqueous and enzymatic oil extraction from a magnetic fluidized bed under the OpenFOAM software,in order to improve the oil quality,yield,and extraction rate of soybean.The free cellulase was also immobilized on a magnetic polymer carrier Fe_(3)O_(4)/SiOx-g-P(GMA)using the glutaraldehyde cross-linking protocols.The carrier was prepared using ethyl orthosilicate and 3-aminopropyl triethoxy,while,the Fe_(3)O_(4) nanoparticles were modified by silane.The magnetically immobilized cellulase with the better magnetic response was obtained for the subsequent flow of magnetizing application in the fluidized bed and the separation after the reaction.Scanning electron microscopy(SEM)images showed that the rough and uneven surface of the carriers significantly increased the surface area of the magnetically immobilized cellulase for the better adsorption of the enzyme.The particle size analysis and SEM images revealed that the particle size of magnetically immobilized cellulase was outstandingly enlarged with a more uniform morphology,compared with the carrier.Correspondingly,Fourier infrared spectroscopy(FIS)verified that the magnetically immobilized cellulase was immobilized on the polymer carrier Fe_(3)O_(4)/SiOx-g-P(GMA).The enzymatic properties of the immobilized cellulase and the free enzyme were evaluated to determine the optimum pH(5)and temperature(60℃)of the immobilized cellulase,indicating that the higher heat,acid,and alkali resistance of the cellulose than before immobilization.The discrete element method(DEM)was used to construct a two-dimensional numerical model of nano-magnetase particles.The OpenFOAM software was selected to obtain the best parameters of hydroenzymatic oil extraction in a magnetic fluidized bed.An optimal combination was achieved for the magnetase with the fluidized state in the fluidized bed,the maximum reaction contact surface,and the maximum oil extraction rate,where the fluid flow rate was 0.0041m/s,and the magnetic field strength was 0.034 T.The instantaneous distribution and speed of the magnetase motion were also measured to clarify the influence of the magnetic field intensity on the magnetase motion trajectory.These optimal parameters were then applied to the circulating magnetic fluidized bed for the water-enzymatic extraction of oil.In addition,a single factor experiment was conducted to optimize the processing parameters for the oil extraction from the magnetic fluidized bed.Specific parameters were gained for the highest extraction rate of soybean oil,where the addition amount of magnetically immobilized cellulase was 1.2 mg/g,the pH value was 5,and the temperature was 55℃,and the reaction time was 120 min.The rate of oil extraction from the magneto-fluidized bed increased by 6.1%,compared with the conventional intermittent reaction.Magnetically immobilized cellulase was used continuously in a magnetic fluidized bed for 12 hours,where the magnetase activity remained above 80%.The finding can provide the basic theoretical support for the environmental performance of the oil process,particularly for the subsequent industrialization of enzymatic oil extraction from the magnetic fluidized bed in the vegetable oil industry.