Application of Magnetic Nano-Immobilized Enzyme in Soybean Oil Degumming: Numerical Simulation in a Liquid-Solid MFB

School of Food Science, Northeast Agricultural University, Harbin 150030, China !e Key Laboratory of Soybean Biology in Chinese Ministry of Education, Northeast Agricultural University, Harbin 150030, China Energy Water Environment and Process Laboratory (LR18ES35), National Engineering School of Gabes, University of Gabes, Gabes 6072, Tunisia Laboratory of Energy Heat and Mass Transfer (LETTM), Faculty of Sciences of Tunis, El Manar University, Tunis 2092, Tunisia School of Computer and Information Engineering, Harbin University of Commerce, Harbin 150028, China


Introduction
Refining technology of edible oil refers to removing impurities, thereby improving the stability and safety of edible oil. Degumming is one of the crucial steps in refining. e primary purpose is to remove the phospholipid-based gums and reduce the impact on the remaining refining processes. Enzymatic degumming can efficiently remove the phospholipids in the CSO. Nowadays, enzymatic degumming commonly used phospholipases A1, A2, and C (PLA 1 , PLA 2 , and PLC). Among them, PLA 1 can specifically hydrolyze Sn-1 in phospholipids, and hydrolysate lysophosphatidic acid has better hydrophilicity than other phospholipids. Immobilized in magnetic Fe 3 O 4 /SiOx-g-P (GMA) nanoparticles, it can effectively remove nonhydrated phospholipids. Nevertheless, lysophospholipids undergo acyl transfer during PLA 1 hydrolysis to reduce their enzymatic efficiency. PLA 2 can hydrolyze the Sn-2 acyl group of fatty acid esters. In previous studies, PLA 2 was successfully immobilized on magnetic MPCSA, MCM, and Fe 3 O 4 /SiOx-g-P (GMA) nanoparticles [1]. PLA 2 immobilization promotes the recovery of enzymes in the process of enzyme degumming. However, PLA 2 enzymatic activity is low, and the produced free fatty acid increases the acidity of oil [2]. PLC hydrolyzes the phospholipid ester bond at the Sn-3 position of phospholipids to form 1,2-diacylglycerol (1,2-DAG) and phosphate monoester [3] and 1,2-DAG is retained in fats and oils. PLC showed a good application prospect in enzymatic degumming. However, free PLC still has many disadvantages, such as low yield and cannot be reused for degumming. e emergence of immobilized enzyme technology has solved the above problems. At this stage, the immobilized enzyme mainly refers to immobilizing the enzyme particle on a carrier to improve its stability and catalytic effect. In recent years, magnetic nanoparticles became much more well known to the public. Fe 3 O 4 magnetic nanoparticles have attracted much attention in their applications because they have the characteristics of nanomaterials as well as the superparamagnetism and high susceptibility of magnetic materials [3,4]. e magnetic polymer carrier prepared with Fe 3 O 4 has strong magnetic responsiveness. Fe 3 O 4 can be quickly separated from other products under the action of an external magnetic field. At the same time, Fe 3 O 4 surface can be modified to carry various functional groups [5] so that Fe 3 O 4 has strong adsorption capacity and good separation characteristics and it is more suitable for magnetic immobilization of enzymes [6]. Due to the porous structure of nanomagnetic particles, smaller particles have a larger specific surface area and higher enzyme content per unit mass of particles [7,8]. After the free PLC is attached to the magnetic carrier, it has the characteristics of magnetic response under the action of the magnetic field. Consequently, CSO can be degummed in a magnetic fluidized bed (MFB). e magnetic particles in the MFB are locked in the magnetic field region, and the reaction substrate can be in contact with the magnetic particles without interruption and quickly separated [9]. Under the action of an appropriate external magnetic field and liquid flow rate, the magnetic particles in the MFB will be in regular fluidization. Regular fluidization can increase the mass and heat transfer rate of the fluid in the bed, thereby increasing the catalytic reaction speed [10]. erefore, the MFB under the action of the magnetic field can be controlled by the direction and the intensity of the magnetic field. erefore, achieving the ideal fluidization state of the liquid-solid twophase inside the MFB provides a continuous degumming reaction. To optimize the enzymatic hydrolysis reaction of an MFB, it is necessary to study the movement law of magnetically immobilized PLC. In recent years, computer numerical simulation technology has gradually become one of the primary methods to study the flow patterns of relatively larger particles in various reactors. However, the study of three-dimensional numerical simulation technology of nanoscale magnetic particles in MFB is limited. 3D numerical simulation technology saves much work compared with experimental research, correspondingly shortens the experimental cycle, and considerably saves the experimental expenses. Moreover, it is difficult to see the pattern of motion and distribution of nanosolid particles in the MFB directly. So, it is imperative to perform detailed simulation on the MFB first. Computational fluid dynamic (CFD) models are usually used to solve and analyze the state of complex phases in an MFB [11].
At present, the mathematical model of liquid-solid twophase flow mostly adopts the Eulerian-Lagrangian method. Eulerian-Lagrangian method regards the main phase as continuous phase and the sparse phase as discrete particles [12]. e main phase uses the Euler method, while the discrete phase uses the Lagrange method for particle tracking. is is the so-called Euler-Lagrange model. In this model, the volume fraction of discrete phase should not exceed 15% [13]. e discrete phase and the main phase have their own pressure, viscosity, and turbulent diffusion sparsity parameters, and the trajectory of discrete phase particles is investigated in the Lagrange coordinate system [14]. e model can analyze the interaction between particles and droplets and the complex interaction between fluids in detail.
is model can avoid the application of a large number of empirical relations and the diffusion problem of discrete phase numerical solution [15]. Although the amount of calculation is huge, the accuracy is higher than that of the Euler model. e results show that the discrete phase model can simulate the liquid-solid two-phase flow more accurately and track the motion of solid particles in the continuous phase.
For CFD simulation tools, many kinds have appeared. Among them, the OpenFOAM simulation technology has gradually become more developed, which can effectively solve the problems in constructing models, depicting grids, solving calculations, extracting data, analyzing data, and visual processing [16,17]. Previous research established a two-dimensional numerical model using the discrete element method with CSO as the substrate [18]. e effects of magnetic field strength and flow on the motion and distribution of PLC-Fe 3 O 4 /SiOx-g-P (GMA) particles under the MFB were studied providing an optimum of the degumming of oil in MFB.
In the current research, single MFB was prepared and connected in series into a multistage liquid-solid MFB circulating degumming system. e optimal parameters of computer numerical simulation obtained by OpenFOAM software were used to study the effects of degumming time, pH value, temperature, and the number of nanomagnetic enzymes on the residual phosphorus content of CSO in a multistage liquid-solid MFB. In this context, the current study aims to increase the enzymatic hydrolysis efficiency and stability and also to improve the degumming effect of CSO without mechanical stirring. e main goal is to achieve the continuous reaction of magnetic particles in MFB and provide a theoretical basis for the continuous removal of phospholipids in CSO.

Preparation of PLC-Fe 3 O 4 /SiOx-g-P (GMA).
Fe 3 O 4 /SiOx-g-P (GMA) PLC particles were prepared according to Jiang et al. [18]. Fe 3 O 4 /SiOx-g-P (GMA) support (1.0 g) was dissolved in 0.1 mol/L phosphate buffer solution with pH 6 for 24 h. After magnetic separation, 0.02 g/mL PLC solution was added and stirred at 55°C for 5 h. Finally, the magnets were separated and washed with phosphate buffer solution three times to obtain PLC-Fe 3 O 4 / SiOx-g-P (GMA) particles. After drying, they were stored in the refrigerator at 4°C, where the amount of enzyme was within the unit mass of the carrier contains.

Multistage MFB Cycle Degumming Process Design.
Since the degumming reaction is a complex process, the variables and reaction conditions need to be dynamically controlled.
erefore, based on the MFB of the reaction main unit, a liquid-solid two-phase MFB degumming reaction system is established, and the ordered connection of each part is designed. e degumming reaction process flow chart of PLC-Fe 3 O 4 /SiOx-g-P (GMA) is presented in Supplementary Figure 1.
e CSO is introduced into the MFB degumming reaction system, and the specific procedure is as follows: the CSO is pumped into the liquid buffer tank (3) from the oil storage tank (1) through the constant flow pump (5), and the valve of the clean oil tank (4) is closed. In the mixer (6), a certain proportion of PLC-Fe3O4/SiOx-g-P (GMA) particles are mixed, and the flow rate is stably input into the MFB (8) through the flow meter (7), and an MFB degumming reaction is performed. Finally, the degumming oil enters the liquid temporary storage tank (11). At the same time, the valve connected to the liquid circulation tank (2) is opened for cyclic degumming and enzymatic hydrolysis. e fat is extracted in real time to determine the phosphorus content until the corresponding standard is reached, and the valve of the recovery oil tank (13) is opened, and the mixture of the degummed oil and the phospholipase is recovered. e MFB continuous enzymatic degumming process is achieved.

PLC-Fe 3 O 4 /SiOx-g-P (GMA)
Degumming. Accurately 300 g of CSO was placed in a 500 mL Erlenmeyer flask, heated to 80°C in water bath, and 0.36 mL 45% citric acid was added for acid-treatment during 20 min at 80°C under 100 r/min. en, cooled to 50°C, and 4% NaOH solution was added to adjust the pH to 5.0. Next, 2% distilled water and 30 mg/kg PLC-Fe 3 O 4 /SiOx-g-P (GMA) were, respectively, added (the ratio of enzyme to oil quality and enzyme water 50 times diluted). e enzymatic degumming test was carried out for 45 min at a stirring speed of 50 r/min. e samples were inactivated in hot water at 90°C for 10 min and centrifuged at 3000 r/min for 15 min.

MFB PLC-Fe 3 O 4 /SiOx-g-P (GMA) Degumming.
e predegumming treatment is the same as in (1). After adjusting the pH, it is passed into the MFB system for degumming test.

Study on the Effect of Nanomagnetic Enzyme on Degumming of CSO.
e effect of nanomagnetic enzyme on the degumming of CSO under different environmental conditions was conducted according to Jiang et al. [18]. Batch degumming was compared with multistage cyclic degumming in MFB.

Detection Method
2.6.1. Determination of Phosphorus Content. Phosphorus content was determined by the AOCS method of 12-55 [19]. In short, 0.4387 g of potassium dihydrogen phosphate was accurately weighed and diluted to 1000 mL, which was the standard stock solution with phosphorus content of 0.1 mg/ mL; 10 mL of standard stock solution was diluted to 100 mL, which was the standard phosphate solution with a phosphorus content of 0.01 mg/mL. 0, 1, 2, 4, 6, and 8 mL phosphate standard solution with a phosphorus content of 0.01 mg/mL was added into a 50 mL colorimetric tube, respectively, and distilled water was added to make up to 10 mL. Meanwhile, 8 mL of hydrazine sulfate solution (0.015%) and 2 mL of 2.5% sodium molybdate dilute sulfuric acid solution were added to the colorimetric tube and heated in boiling water bath for 10 min. After cooling to room temperature and let stand for 10 min, the absorbance of the solution was measured at 650 nm. e regression equation was y � 5.4072x + 0.0061 and r � 0.9997, with the absorbance as ordinate and the phosphorus content (0.00, 0.01, 0.02, 0.04, 0.06, 0.08 mg) as abscissa. e test oil sample (3 g) was accurately weighed, and ZnO (0.5 g) was added and burned in a muffle furnace at 550-600°C to obtain the ash, then dissolved completely with 10 mL hydrochloric acid solution (the ratio of concentrated hydrochloric acid to water is 1 : 1) and heated to boiling. e remaining solution was neutralized with 50% sodium hydroxide solution until turbidity appears. Hydrochloric acid solution was slowly added to dissolve all zinc oxide precipitates. e sample is cooled to room temperature and diluted in a 100 mL volumetric flask. As in the standard curve drawing, 10 mL of the measured solution was injected into 50 mL colorimetric tube, and 8 mL of hydrazine sulfate solution (0.015%) and 2 mL of 2.5% sodium molybdate dilute sulfuric acid solution were added to the colorimetric tube and heated in boiling water bath for 10 min. After cooled to room temperature and let stand for 10 min, the absorbance of the solution was measured at 650 nm. e phospholipid content in the sample was calculated according to the following equation: where X: phospholipid content (mg/mL); P: the phosphorus content of the tested solution obtained from the standard curve (mg); V: volume of oil sample (mL); V 1 : volume of sample diluted after ashing (mL); V 2 : volume of the solution to be measured in colorimetry (mL); 26.31: each milligram of phosphorus is equivalent to milligrams of phospholipids.

PLC Enzyme Activity
Determination. e activity of the PLC was determined by the method of Jiang et al. [20]. 250 mmol/L tris-HCl buffer of pH 7.2, 1 mmol/L ZnCl 2 , and 10 mmol/L p-NPPC were mixed in 2 mL reaction system. e mixture was incubated for 5 min at 37°C, and an appropriate dilution of the enzyme was added to be tested. 100 μL of the solution was kept to react for 30 min, and the absorbance was measured at a wavelength of 410 nm. e PLC enzyme activity is defined as the amount of enzyme required to produce 1 nmol of p-nitrophenol per minute at pH 7.2 and 37°C as one enzyme activity unit (U). e PLC enzyme activity was calculated according to the following equation: where 1.3636 × 10 3 : reaction conversion factor; A: absorbance; T: reaction time, min.

Detection of Iron in Fats and Oils.
Oil samples were taken at the exit of any MFB, and the iron content was determined according to Ravasi et al. [21].

MFD Model and Nanomagnetic Enzyme
Characteristics. e size of the inner diameter of the MFB reactor to be designed is Φ20 × 300 mm (MFB bed width × height), and 8.67 × 10 −3 g nanomagnetic enzyme was added into the MFB reactor and the number of particles, which selected 3000 nanomagnetic enzyme particles as the research object; the three-dimensional cylinder with a diameter of 11 μm and a height of 22 μm area of model was designated for the computer simulation as presented in Supplementary Figure 2.

Mathematical Formulation.
e main mathematical solution model is the Euler-Lagrangian model which considers liquid-phase oil as continuous phase and nanomagnetic enzyme as discrete phase [14,15] simulation based on MP-PIC discrete control equation, while the equation of motion of two-phase flow adopts Navier-Stokes and refers to Yu et al. [22]. A longitudinal magnetic field was introduced to study the distribution, velocity, and flow of the nanomagnetic enzyme particles at this time. e governing equations are as follows: (i) Liquid-phase equations: (i) Mass conservation (continuity) equation: Here, the concentration, density, and velocity of the liquid phase are, respectively, ε l , ρ l , and v l . (ii) Momentum conservation equation: (i) In (4), g is the gravity acceleration; ρ is the liquid pressure; β is the drag coefficient of the liquid-solid two phase; and τ 1 is the liquid-phase stress tensor, which can be calculated by the following formula: (ii) Solid-phase equations: (i) Mass conservation equation: Here, the concentration, density, and velocity of the solid phase are, respectively, ε s , ρ s , and v s . (i) Momentum conservation equation: Here, g is the acceleration of gravity; β is the drag coefficient of liquid-solid two-phase; and τ s is the liquid-phase stress tensor, which can be calculated by the following formula: Here, the pressure p s , the viscosity ξ s and the dynamic viscosity μ s are given by the following formulations: In equations (9)- (11), e is the solid-phase collision return coefficient and g 0 refers to the contact probability used to correct the discrete phase and is specifically determined by the Bagnold equation [23]. e drag coefficient of the liquid-solid two phase β can be calculated by referring to the Gidaspow formula as follows: coefficient C d in equation (12) which depends on the Reynolds number can be estimated by using the following formulation: Reynolds number R e is given as follows: (

1) Magnetic Field Correlation Equation.
After the introduction of the magnetic field, each solid phase (particle) needs to be subjected to force analysis [24], that is, for particle i, obtained by Newton's second law: Here, f mi denotes the virtual mass force acting on the particle i. Among them, f d is indicating drag and considers the following factors: where f cj is a contact force applied on the magnetized nanoparticle enzyme due to the collision between the particles. f lj represents the lubricating force applied on the non-nanomagnetic enzyme particle by the oil.
In equations (13) and (14), m i , v i , and V p are the mass, velocity, and volume of the solid phase, respectively. T p , I p , and ω are the torque, moment of inertia, and angular velocity of the component in the tangential direction of the force tangential direction.
In equation (15), ε l and β are the liquid-phase volume and the momentum transfer coefficient, respectively. Under the influence of a magnetic field, the nanomagnetic enzyme particle is subjected to the effect of a magnetic force which is composed of two components [24,25]. It is written as follows: where F me represents the external applied magnetic force and F mi denotes the magnetic force due the magnetic interaction between the particles. As an important factor, the susceptibility coefficient needs to be considered separately [26]. erefore, the susceptibility of the MFB as a whole and the susceptibility of the discrete phase need to be closely related. ey are related by the following formulation: Here, x p represents the solid-phase magnetic susceptibility.
where M is the magnetic moment of the fluid particle and H denotes the magnetic field. e magnetic interactions between nanomagnetic enzyme particles are presented in Supplementary Figure 3, where r denotes the distance between particles enzyme A and B and B 0 is the intensity of the applied uniform magnetic field. m a and m b are the magnetic moment of nanoparticles A and B, respectively [27]. F r represents the radial component and F θ represents the orthoradial component of the interparticle magnetic force F mi applied by particle A on particle B. e two components F r and F θ are obtained by projecting the F mi force in the polar base (r, θ). ey are given by the following expressions: (i) Radial component: Journal of Food Quality (ii) Orthoradial component: e variations of the magnetic moment m of the enzyme particle in the radial and orthoradial directions are given by the two following equations: zc zθ � 2 3 x e V p /8πr 3 sin 2 θ 2 + 6 x e V p /8πr 3 cos 2 θ 1 + x e V p /8πr 3 (3 cos 2 θ − 1) 1 e two angles c and θ, indicated in Supplementary  Figure 3, are related by the following formulation:

Numerical Procedure and Meshing
Choice. e above governing equations are solved by using the discrete element method (DEM) [28,29]. e CSO is used as the liquid-phase fluid, and the nanomagnetic enzyme particles are used as the solid phase. Since the particles are too small, the particle cloud calculation method is adopted, and the number of particle clouds is regarded as the number of particles in the simulation process. e relevant physical properties and initial parameters of the MFB simulation are shown in Table 1. e solver in OpenFOAM v1706 is used to solve the problem. In the simulation process, 666,600-time steps are calculated with an iteration step of 3 × 10 −5 s, and the total calculation time is 19.99 s. Computer configuration: Intel Pentium Dual Core E5300 2.6 GHz dual-core processor, 4G memory, and each data operation time is about 96 h-144 h range. e three-dimensional cylindrical MFB model was established by using OpenFOAM preprocessing software. e MFB model was meshed by Block Mesh. e wall of the MFB was mainly divided by rectangular grid, while the bed top and bottom as the connecting part of the wall were divided by a circular mesh. e grid size is determined based on the retention rate of the nanomagnetic enzyme. e grid model is shown in Figure 1.

Pore Size of Porous Plate.
e main function of the porous plate in the MFB is to achieve a better fluidization state of the internal particles by changing the liquid flow field. By adjusting the ratio of the opening area to the whole plate, the specifications of the porous plates with different opening ratios are shown in Figure 2.

Magnetic Field Strength.
e Hall magnetic intensity detector is used to measure the field strength of different parts in the MFB, and the output signal is output to the V/F converter. e microprocessor performs the counting and calculation of the output signal and converts the analog value into a numerical value at each moment. e measurement results displayed on the screen are accurate [30]. e current is used to generate the magnetic field. e relationship between the current intensity and the magnetic field strength is shown in Table 2. e magnetic field strength 0∼0.03T corresponds to the matching current.
e Hall magnetic field strength detection tool is used to detect the magnetic field strength. e strength of the magnetic field can be changed according to the strength of the incoming current (Table 2).

Data Processing.
ree experiments were carried out, and all values were presented as mean ± standard deviation. Data processing and plotting was performed using Origin 8.5 using Design Expert 8.0.6 to optimize the degumming process parameters and SPSS software for data, statistics, and correlation analysis.

Effect of Grid Scale on Nanomagnetic Enzyme
Distribution. Figure 3 shows the influence of three different grid sizes on the distribution of nanomagnetic enzymes at a certain height inside the MFB device. According to Figure 3(a), the content of nanomagnetic enzyme is reduced in the middle region, but higher in the vicinity of the inner wall of the device. At the same time, different grid sizes have little effect on the overall nanomagnetic enzyme distribution in the middle area of the MFB device.
It can be noticed from Figure 3(b) that when the number of grids is small (10 × 200), the polyline of the nanomagnetic enzyme distribution state shows a significant oscillation phenomenon, making the calculation inaccurate [31,32].
is is mainly because grid points are relatively far away from each other. When the number of divisions is large (20 × 300 and 30 × 400), the nanomagnetic enzyme distribution tends to be flat. erefore, in consideration of the calculation time, a grid size of 20 × 300 mm is used in this study. . Figures 4(a) and 4(b) show four different perforated plates whose opening ratio is proportional to the number of openings. In the middle area of the MFB device, the flow rate of the CSO is 150 mm 0.01 m/s, with reference to the effect of the pore size of the multiwell plate designed on 2.3.5 on the distribution of nanomagnetic enzymes. e porosity of different multiwell plates has a significant effect on the nanomagnetic enzyme distribution. When the open porosity is 22.5%, the nanomagnetic enzyme distribution is unstable, and the calculation result of its unevenness is high. e reason may be that the open porosity of the perforated plate is low, and the CSO is formed when it enters the bed through the perforated plate. In the spouted bed, a strong impact on the nanomagnetic enzyme phase is shown, making the nanomagnetic enzyme phase moving disorderly. When the open porosity is 30%, the uniformity of the nanomagnetic enzyme distribution has been significantly improved. e unevenness greatly decreased, but the nanomagnetic enzyme distribution at the same bed height is still unstable. When the open porosity is 37.5%, the nanomagnetic enzyme particle unevenness is low, and its nanomagnetic enzyme is at the axial height of 150 mm. e distribution state is relatively stable. When the open porosity is 45%, due to the large open porosity, the expansion height of the bed layer on the porous plate increases, and the nanomagnetic enzyme particle distribution becomes unstable again. e nonuniformity of the porosity of different perforated plates is compared. When the porosity is 30% to 45%, the nonuniformity is low. Combining with the uniform distribution curves of the nanomagnetic enzyme distribution in Figure 5(a), it can be concluded that when the rate is 37.5%, the magnetic phase distribution effect is the finest.

Influence of CSO Flow
Rate on the Distribution of Nanomagnetic Enzymes. Figure 5 shows the effects of the three types of CSO flow velocity on the distribution of nanomagnetic enzymes at different axial heights inside the MFB device. According to Figure 5(a), the nanomagnetic enzyme particles have different nanomagnetic enzyme distribution states at the same height under the conditions of different CSO flow rates. When the flow rate of the CSO is slow, the content of the nanomagnetic enzyme is higher near the entrance of the CSO. is is mainly due to the larger effect of the nanomagnetic enzyme because of gravity, which is prone to accumulation. e nanomagnetic enzyme content at the same position is reduced, so the increase of the flow velocity of the CSO increases with the height of the bed expansion, so that the nanomagnetic enzyme particles move to the upper part of the bed [33]. Figure 5(b) shows that when the internal height of the intercepted MFB device increases to near the outlet of the CSO, the velocity of the CSO increases. Accordingly, its ability to carry nanomagnetic enzyme particles is enhanced. When the velocity of CSO decreases, the height of the corresponding bed expansion decreases, and the nanomagnetic enzyme content decreases. At the same time, when the flow rate of the CSO is low, the nanomagnetic enzyme particles have relatively uniformly distributed inside the MFB device. erefore, to select the optimal CSO flow rate, further consideration must be given to the movement state of the nanomagnetic enzyme.

Effect of CSO Flow Rate on Nanomagnetic Enzyme
Movement Speed. Figure 6 shows the particle velocity vector diagram of different flow velocity of CSO. When the fixed field strength is 0.02 T, the velocity of different CSO is used as the initial parameter. According to the simulation results, when the same physical time is intercepted for 6s, the direction of the particle is represented by the direction of the arrow, and the color indicates the speed value to investigate the velocity change of nanomagnetic enzyme particles at a height of 150 mm inside the MFB device. e liquid flow velocity needs to be selected according to the fluidization state of the internal suspended magnetic particles. When the flow rate of the CSO is 0.001 m/s, the speed of the nanomagnetic enzyme particles is stable within the range of 0.005 to 0.015 m/s. From the direction of particle speed, although the particles move up and down the wall along the regular middle part of the MFB, the velocity change value is smaller than the flow rate of the CSO 0.01 m/s, so the particle phase is more floating. Consequently, the particle contact with the CSO is reduced, which will affect the degumming process.    Journal of Food Quality When the flow rate of the CSO increases to 0.1 m/s, the graph shows that the range of particle speed changes fluctuates significantly, showing turbulence. is may be due to the increase in the CSO speed, which causes the force distribution of the nanomagnetic enzyme to be uneven, which does not show a good fluidization effect. In summary, the selection of 0.01 m/s for the flow rate of the CSO has the finest driving effect on the nanomagnetic enzyme.

Effect of Magnetic Field Strength on Bed Pressure.
To study the influence of magnetic field strength on the movement state of nanomagnetic enzyme particles, the stability of the bed inside the MFB device needs to be studied firstly. e pressure at the bottom of the bed can clearly show the effect of different magnetic field strength on the bottom of the bed. e flow rate of the CSO phase was 0.01 m/s, the porosity of the perforated plate was 37.5%, and the magnetic field intensity range was 0∼0.03T [34]. e physical time was 4, 6, 8, and 10 s. e strength of the magnetic field plays a key role in the distribution of the nanomagnetic enzyme particles. In simulation, we need to increase the magnetic force of the interaction between the nanomagnetic enzyme particles, so that the particles aggregate to form a state of tiny magnetic chains, so that the liquid can easily pass through the magnetic chains. e voids flow through which is more conducive to the degumming reaction [35][36][37]. When particles exist in the state of tiny magnetic chains, they will be subjected to greater gravity to settle, which will also increase the pressure at the bottom of the bed. According to Figure 7, there is no magnetic field, the phase-to-phase coupling effect of the nanomagnetic enzyme phase is small, and the effect of the velocity of the oil flow is large. us, the effect on the bottom pressure of the bed is small. e pressure at the bottom of the bed increases with the increase of the field strength. When the field strength is 0.02-0.03 T, the pressure at the bottom of the bed decreases with the increase of the field strength.

Effect of Magnetic Field
Intensity on the Distribution of Nanomagnetic Enzymes. When the magnetic field strength is stable, the distribution of nanomagnetic enzymes shows a high distribution state, so it is necessary to study the distribution of nanomagnetic enzymes at different field strengths. e flow rate of the CSO is 0.01 m/s, the opening   , it is not difficult to find that, with the increase of the field strength, the nanomagnetic enzyme distribution state distribution gradually stabilizes, and the values of the nanomagnetic enzyme content at different axial heights in the MFB device are uniform. Under the magnetic field, the fluidization quality of the nanomagnetic enzyme particles is significantly improved. At the same time, increasing the magnetic field can also effectively suppress the expansion effect of the bed and reduce the expansion height of the bed [38]. Consequently, the bed enters a more stable state of magnetic fluidization. e simulation results show that when the magnetic field strength is 0.02 T, the fluctuation range of the curve of the nanomagnetic enzyme distribution state is small, indicating that the particle phase can form a fluidized state stably at this time, and therefore, the optimal magnetic field strength is 0.02 T.

Study on the Effect of Nanomagnetic Enzyme on
Degumming of CSO. e results of cyclic degumming of nanomagnetic enzyme particles in a batch reaction system and a multistage MFB are shown in Table 3. e degumming time was shortened by 0.5 h, the relative enzyme activity was 7% higher at the same time, and the output of neutral oil was significantly improved. In a MFB reaction system, under the optimal reaction conditions, the phosphorus content in soybean degummed oil can be reduced to 55.73 mg/kg. is indicates that, under the action of magnetic field, nanomagnetic enzyme particles are evenly distributed in a fluidized state in a MFB to form a ring-core flow [39][40][41]. ese optimal reaction conditions promoted the dispersion of nanomagnetic enzyme particles in the oil phase and the water phase, thereby forming a more uniform reaction system.

Conclusion
In this experiment, the theoretical parameters of the optimal motion state of nanomagnetic enzyme in MFB were simulated by the computer. Based on the simulated theoretical parameters, the nanomagnetic enzyme was applied to the multistage circulating MFB for CSO degumming. e effects of mesh size, opening rate, crude oil flow velocity, and magnetic field intensity on the particle movement and the stability of the MFB were studied. It was found that, under the optimal parameters, the degumming time was shortened, and the mechanical damage of nanomagnetic enzyme was reduced. e results showed that compared with intermittent degumming, multistage cyclic degumming with nanomagnetic enzyme in the magnetic fluidized bed did not need mechanical stirring. e activity loss rate of nanomagnetic enzyme in multistage MFB was reduced. e amount of nanomagnetic enzyme needed was reduced, the phosphorus content was reduced, and the 1,2-DAG content was increased. e nanomagnetic enzyme was dispersed uniformly under the magnetic force forming core-annular flow law.
is study provides a theoretical basis for the continuous removal of phospholipids in crude soybean oil by nanomagnetic enzyme particles in the MFB.

Data Availability
Data are available within the article and its supplementary materials.

Conflicts of Interest
e authors declare that they have no conflicts of interest.