Preparation method and application of modified magnesium oxide adsorbent by tussah silk sericin

Abstract

This invention belongs to the field of wastewater treatment reagent technology, and particularly relates to a preparation method and application of a magnesium oxide adsorbent modified with silkworm sericin. The method includes loading, separation, washing, and drying. MgO is added to the cocoon-boiling wastewater and reacted under reciprocating conditions in a gas bath constant-temperature shaker, resulting in uniform dispersion of magnesium oxide in the wastewater. Sericin acts as a modifier and is loaded onto the magnesium oxide. The reactants are precipitated, dried, and ground into a fine powder to obtain the S-MgO adsorbent. The beneficial effects of this invention are: the viscous sericin in the cocoon-boiling wastewater "encapsulates" and "bonds" magnesium oxide particles to form composite aggregates, and the functional groups of sericin and magnesium oxide are complementary, thus optimizing the pore structure of magnesium oxide. The adsorption rate for methylene blue reaches 90.30%, far exceeding the 11% adsorption efficiency of MgO before modification. More importantly, it achieves the recycling of sericin in the cocoon-boiling wastewater, achieving the goal of "treating waste with waste," and has broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment reagent technology, and particularly relates to a preparation method and application of a magnesium oxide adsorbent modified with silkworm fibroin. Background Technology

[0002] Sericin (S) is a hydrophilic macromolecule rich in highly polar groups, composed of amino acids such as serine, aspartic acid, and glycine, and including active groups such as -OH, carboxyl, and -NH2. my country produces approximately 200,000 tons of silk annually. For every 10,000 tons of raw silk produced, about 2,000 to 3,000 tons of sericin are discharged with wastewater, resulting in protein content of approximately 500 mg / L and COD exceeding 3800 mg / L in the cocoon-boiling wastewater. This not only causes severe environmental pollution but also represents a significant waste of valuable sericin as waste. Magnesium oxide (MgO) is a white alkaline earth metal oxide with a high melting point, non-toxicity, and low solubility. As an adsorbent, magnesium oxide lacks sufficient hydroxyl groups on its surface. Unmodified magnesium oxide is mainly composed of micropores (<2 nm), which cannot accommodate the large molecular size of methylene blue, resulting in a low adsorption capacity.

[0003] Dyes are widely used in the food, cosmetics, and dyeing industries. They are characterized by complex molecular structures, vibrant colors, significant toxicity, and poor biodegradability. Due to the complex composition and difficulty in degradation of dye wastewater, it has become one of the most challenging industrial wastewaters to treat in China, threatening not only aquatic ecosystems but also human health. Currently, the main methods for treating dye wastewater include: 1) Activated carbon adsorption: This method utilizes the solid surface of activated carbon to adsorb one or more substances from water to purify the water. The adsorption rate for dyes is >95%, but regeneration is difficult, costs are high, and selectivity is poor. 2) Clay mineral adsorption: Clay minerals mainly rely on surface adsorption and ion exchange adsorption for dyes, achieving an adsorption rate of 70%-95%. However, because most dye molecules are large, their adsorption capacity is low and separation is difficult. 3) Biomass adsorption method: Biomass materials, such as biochar and modified cellulose, form porous structures after carbonization or activation. They physically adsorb and retain dye molecules, especially small molecule dyes, achieving an adsorption rate of 80%-99%. However, this method is unstable, easily degraded, and causes secondary pollution. 4) Chitosan adsorption method: Chitosan (CS) is a natural polymer produced by the deacetylation of chitin in shrimp and crab shells. It contains amino cations and exhibits hydrophilicity, making it suitable as a dye adsorbent with an adsorption rate of 85%-98%. However, chitosan is soluble in acid, has poor strength, and is difficult to recover. 5) Ion exchange resin adsorption method: The adsorption mechanism of ion exchange resins relies mainly on the charge interaction between exchangeable ions on their surface or inside and dye molecules. The adsorption rate is 90%-99%, but the cost is extremely high, selective competition reduces the effective adsorption capacity of the resin, and a large amount of regeneration waste liquid is generated. 6) Electrochemical oxidation: Electrochemical oxidation utilizes strong oxidizing substances generated by electrochemistry to oxidize and decompose organic matter, reducing dyes, color, and turbidity. The adsorption rate for dyes is 90%-99.9%, but it is energy-intensive, electrodes are expensive, and byproducts increase environmental risks. 7) Oxidation-reduction method: Oxidation-reduction adsorption of dye wastewater involves electron transfer reactions between the redox active groups on the adsorbent surface and dye molecules, degrading or converting them into substances with lower or no toxicity. The degradation rate for dyes is 70%-95%, but it consumes large amounts of reagents and generates significant amounts of sludge. The dye removal rates of the above methods are for low to medium concentration dye wastewater (50 mg / L-100 mg / L).

[0004] Magnesium oxide alone suffers from problems such as charge repulsion, pore limitation, and insufficient chemical interaction. The adsorption efficiency of MgO before modification is only 11%. How to overcome the limitations of traditional dye treatment technology and achieve more efficient, economical, and environmentally friendly dye wastewater treatment is a topic that has been rarely reported. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing and applying a magnesium oxide adsorbent modified with silkworm sericin, overcoming the shortcomings of existing technologies. By using sericin and magnesium oxide to make a composite adsorbent, the excellent biocompatibility, abundant active functional groups, and biodegradability of sericin are combined with the advantages of magnesium oxide, such as high specific surface area, alkaline surface, and low cost. After composite preparation, the material simultaneously possesses all the adsorption sites of magnesium oxide and sericin, forming a multi-mechanism, multi-site synergistic adsorption system, achieving efficient and rapid adsorption of methylene blue, and achieving the effect of "using waste to treat waste".

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a magnesium oxide adsorbent modified with tussah silk fibroin includes loading, separation, washing, and drying. The specific preparation steps are as follows:

[0008] For loading, weigh 0.8-1.5g of dried MgO and slowly add it to 100 mL of sericin solution. React in an air bath constant temperature shaker at 30-60℃ and 120-210 r / min for 60-240 min to ensure that magnesium oxide is uniformly dispersed in the sericin solution and that sericin is fully loaded on magnesium oxide.

[0009] Separate the mixture after reaction by transferring it to a centrifuge tube and centrifuging it at 8000 r / min for 10 min to separate the complex precipitate. Discard the supernatant and retain the precipitate.

[0010] Wash the precipitate 2-3 times with deionized water to remove unreacted sericin and magnesium oxide. Centrifuge after each wash and discard the supernatant.

[0011] Drying: Place the washed precipitate in an oven and dry at 60-80 ℃ for 12-24 h. Grind the dried composite into fine powder using a mortar and pestle or a ball mill to obtain S-MgO adsorbent.

[0012] Furthermore, the preparation process of the sericin solution is as follows: 1) The dried tussah silkworm cocoon shells and 0.5% sodium carbonate solution are soaked in an Erlenmeyer flask at a volume ratio of 1:30, and the sericin solution is obtained at 120 ℃ for 30 min; 2) After cooling to room temperature, the solution is filtered with gauze, refrigerated and stored for later use.

[0013] Furthermore, in step 1), 0.8-1.5g of dried MgO is weighed and added to an Erlenmeyer flask, and 100 mL of sericin solution is slowly added. The mixture is then reacted in an air bath constant temperature shaker at 50 ℃ and 180 r / min for 180 min.

[0014] Furthermore, the reciprocating condition is a reciprocating cylinder.

[0015] Furthermore, the S-MgO adsorbent product is used for adsorbing methylene blue, carmine, methyl orange and reactive red dyes, with an addition amount of 0.15 g-0.2 g / 100 mL of dye-simulated wastewater at a concentration of 100 mg / L.

[0016] Furthermore, the S-MgO adsorbent product achieved an adsorption rate of 90.30% at 40 °C, 150 r / min, an S-MgO adsorbent dosage of 0.2000 g, an initial methylene blue concentration of 100 mg / L, a treatment volume of 100 mL, and a shaking time of 60 min.

[0017] The present invention utilizes the working principle of preparing modified magnesium oxide adsorbent from tussah silkworm sericin and magnesium oxide. The viscous sericin solution acts as a "bio-glue" to "encapsulate" and "bind" magnesium oxide particles, forming a composite aggregate. At the same time, the functional groups of sericin and magnesium oxide are complementary, and the sericin optimizes the pore structure of magnesium oxide, giving it the best adsorption performance for methylene blue.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1) This invention uses sericin from cocoon-boiling wastewater and magnesium oxide to create a composite adsorbent. This adsorbent achieves a methylene blue removal rate of 86%-90.3% in 100 mg / L methylene blue dye wastewater. It not only recovers sericin from the cocoon-boiling wastewater, reducing the organic matter content and alleviating the pressure on subsequent wastewater treatment, but also solves the problems of charge repulsion, pore limitation, and insufficient chemical interaction of magnesium oxide alone. Realizing the recovery and utilization of sericin from wastewater is a typical example of "waste resource utilization" and "high-value-added utilization," indicating that S-MgO has high application and environmental value.

[0020] 2) By performing SEM, FT-IR, BET and XRD analyses on the S-MgO8 powder before and after modification and after adsorption, and by regenerating the adsorbed S-MgO8 powder three times, it was found that the regeneration effect was good and it has the potential for implementation and promotion.

[0021] 3) The modified magnesium oxide adsorbent S-MgO8 of this invention also has good adsorption performance for carmine, methyl orange and reactive red dyes. The results show that S-MgO can be used for adsorption of various dye wastewaters and has broad application prospects. Attached Figure Description

[0022] Figure 1These are SEM comparison images of MgO, S-MgO8, and S-MgO8+MB in Example 1 of this invention (a, b, and c are SEM images of MgO, S-MgO8, and S-MgO8+MB at a magnification of 10k; d, e, and f are SEM images of MgO, S-MgO8, and S-MgO8+MB at a magnification of 5k).

[0023] Figure 2 The following are comparative graphs showing the testing and characterization of the adsorbent product in Example 1 of this invention: (2-1 is the FT-IR test curve, 2-2 is the BET test curve, 2-3 is the BET particle size distribution test curve, and 2-4 is the XRD test curve).

[0024] Figure 3 This is a graph showing the effect of the volume of the sericin solution on the adsorption effect in Example 1 of the present invention.

[0025] Figure 4 This is a graph showing the effect of MgO dosage on adsorption efficiency in Example 1 of the present invention.

[0026] Figure 5 This is a graph showing the effect of preparation temperature on adsorption efficiency in Example 1 of the present invention.

[0027] Figure 6 This is a graph showing the effect of rotational speed on adsorption efficiency in Example 1 of the present invention.

[0028] Figure 7 This is a graph showing the effect of preparation time on adsorption efficiency in Example 1 of the present invention.

[0029] Figure 8 This is a graph showing the effect of the dosage of S-MgO8 on the adsorption effect in Example 1 of the present invention.

[0030] Figure 9 This is a graph showing the effect of adsorption time on adsorption efficiency in Example 1 of the present invention.

[0031] Figure 10 This is a graph showing the effect of the number of regeneration cycles on the regeneration efficiency in Example 1 of the present invention.

[0032] Figure 11 This is a graph showing the adsorption effect of Reactive Red on Example 1 of the present invention.

[0033] Figure 12 This is a graph showing the adsorption effect of carmine on Example 1 of the present invention.

[0034] Figure 13 This is a graph showing the adsorption effect of methyl orange on Example 1 of the present invention.

[0035] Figure 14 This is a graph showing the effect of the volume of the sericin solution on the adsorption effect in Example 2 of the present invention.

[0036] Figure 15 This is a graph showing the effect of preparation temperature on adsorption efficiency in Example 2 of the present invention.

[0037] Figure 16 This is a graph showing the effect of rotational speed on adsorption efficiency in Example 2 of the present invention.

[0038] Figure 17 This is a graph showing the effect of preparation time on adsorption efficiency in Example 2 of the present invention.

[0039] Figure 18 Example 2S-MgO of the present invention 10 Curve showing the effect of dosage on adsorption efficiency;

[0040] Figure 19 This is a graph showing the effect of adsorption time on adsorption efficiency in Example 2 of the present invention.

[0041] Figure 20 This is a graph showing the effect of the volume of the sericin solution on the adsorption effect in Example 3 of the present invention.

[0042] Figure 21 This is a graph showing the effect of preparation temperature on adsorption efficiency in Example 3 of the present invention.

[0043] Figure 22 This is a graph showing the effect of rotational speed on adsorption efficiency in Example 3 of the present invention.

[0044] Figure 23 This is a graph showing the effect of preparation time on adsorption efficiency in Example 3 of the present invention.

[0045] Figure 24 Example 3S-MgO of the present invention 15 Curve showing the effect of dosage on adsorption efficiency;

[0046] Figure 25 This is a graph showing the effect of adsorption time on the adsorption effect in Example 3 of the present invention. Detailed Implementation

[0047] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0048] To more clearly illustrate the technical solutions in the specific embodiments of the present invention or the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The components of the embodiments of the present invention described and shown in the accompanying drawings can typically be arranged and designed in many different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention.

[0049] The experimental reagents used in the experiments in this embodiment are shown in Table 1, the instruments used are shown in Table 2, and the preparation instructions for each standard reagent are shown in Table 3.

[0050] Table 1

[0051] name purity factory Anhydrous sodium carbonate Analytical Pure Tianjin Damao Chemical Reagent Factory magnesium oxide Analytical Pure Tianjin Damao Chemical Reagent Factory Methylene blue Analytical Pure Tianjin Kehua Reagent Co., Ltd. Methyl orange 96 % Shanghai McLean Biochemical Technology Co., Ltd. Rouge Analytical Pure Shanghai McLean Biochemical Technology Co., Ltd. Active Red 24 Analytical Pure Shandong Keyuan Biochemical Co., Ltd. Anhydrous ethanol Analytical Pure Tianjin Fuyu Fine Chemical Co., Ltd.

[0052] Table 2

[0053] name model Manufacturer Electronic balance FA1004 Shanghai Shunyu Hengping Scientific Instruments Co., Ltd. Far-infrared rapid dryer WS-70-1 Shanghai Sunshine Experimental Instruments Co., Ltd. air bath constant temperature oscillator THZ-92B Shanghai Boxun Medical Bio-Instrument Co., Ltd. Portable high-pressure steam sterilizer DSX-18L Shanghai Shenan Medical Equipment Factory Medical centrifuge TG16-WS Changsha Xiangyi Centrifuge Instrument Co., Ltd. Ultraviolet spectrophotometer UV756 Shanghai Youke Instruments Co., Ltd. Intelligent digestion device SH-30A Jiangsu Shengaohua Environmental Protection Technology Co., Ltd. Water quality tester 6B-3000A Jiangsu Shengaohua Environmental Protection Technology Co., Ltd. Ultrasonic cleaning machine ZX-5200DE Shanghai Zhixin Experimental Instrument Technology Co., Ltd. Scanning electron microscope SU8100 HITACHI Corporation of Japan Fourier transform infrared spectrometer Thermo Nicolet iS5 Thermo Fisher Scientific X-ray diffraction instrument XRD-6100 Shimadzu Specific surface porosity meter ASAP2460 Micro Instruments

[0054] Table 3

[0055] Serial Number Reagent Name Preparation process 1 0.5% sodium carbonate solution Accurately weigh 5.0000 g of sodium carbonate, and then dissolve it completely in an appropriate amount of water. After the sodium carbonate is completely dissolved, transfer it to a 1 L volumetric flask and dilute to the mark. 2 50 mg / L methylene blue solution Accurately weigh 0.0125 g, 0.0250 g, 0.0375 g, and 0.0500 g of methylene blue, respectively, and transfer them to beakers. Add a certain amount of deionized water and stir with a glass rod until the methylene blue is completely dissolved. Then transfer the mixture to a 250 mL volumetric flask. Add a small amount of distilled deionized water to the beaker and stir rapidly with a glass rod. Continue to transfer the mixture to the 250 mL volumetric flask until the beaker is clear and there is no methylene blue solution remaining. Dilute to the mark. 3 100 mg / L methylene blue solution 4 150 mg / L methylene blue solution 5 200 mg / L methylene blue solution 6 100 mg / L methyl orange solution Accurately weigh 0.0250 g of methyl orange and transfer it to a beaker. Add a certain amount of deionized water and stir with a glass rod until the methyl orange is completely dissolved. Then transfer it to a 250 mL volumetric flask. Add a small amount of distilled deionized water to the beaker and stir rapidly with a glass rod. Continue to transfer the mixture to the 250 mL volumetric flask until the beaker is clear and there is no remaining methyl orange solution. Dilute to the mark. 7 100 mg / L carmine solution Accurately weigh 0.0250 g of carmine and transfer it to a beaker. Add a certain amount of deionized water and stir with a glass rod until the carmine is completely dissolved. Then transfer it to a 250 mL volumetric flask. Add a small amount of distilled deionized water to the beaker and stir rapidly with a glass rod. Continue to transfer the mixture to the 250 mL volumetric flask until the beaker is clear and there is no carmine solution remaining. Dilute to the mark. 8 100 mg / L Active Red Solution Accurately weigh 0.0250 g of Reactive Red and transfer it to a beaker. Add a certain amount of deionized water and stir with a glass rod until the Reactive Red is completely dissolved. Then transfer it to a 250 mL volumetric flask. Add a small amount of distilled deionized water to the beaker and stir rapidly with a glass rod. Continue to transfer the mixture to the 250 mL volumetric flask until the beaker is clear and there is no remaining Reactive Red solution. Make up to the mark. 9 80% anhydrous ethanol solution Measure 80 mL of analytical grade anhydrous ethanol solution using a graduated cylinder, and add 20 mL of distilled water to make up to 100 mL in a volumetric flask.

[0056] The process of constructing the methylene blue standard curve for the experiment is as follows: Using a UV spectrophotometer, the absorption spectrum of a 10 mg / L methylene blue solution was precisely scanned and analyzed within the wavelength range of 400 nm to 800 nm, with a maximum absorption wavelength λmax = 664 nm. An appropriate amount of 100 mg / L methylene blue solution was diluted to prepare methylene blue standard solutions with concentrations of 0.50, 1.00, 2.00, 3.00, and 4.00 mg / L, respectively. The absorbance value A of each diluted standard solution was measured at a wavelength of 664 nm. Finally, a standard curve was plotted with the concentration of the standard methylene blue solution (mg / L) on the x-axis and the measured absorbance value A on the y-axis.

[0057] The adsorption test procedure is as follows: Take a 150 mL conical flask, add 100 mL of 100 mg / L methylene blue simulated wastewater, accurately weigh 2.000 g of S-MgO and add it to the conical flask. React in a gas bath constant temperature shaker at 40 ℃ and 150 r / min for 60 min. After standing for 5 min, set the wavelength to 664 nm in a UV756 ultraviolet-visible spectrophotometer, use a syringe to draw up the supernatant and filter it through a filter membrane, and measure the absorbance value A of the sample solution.

[0058] The calculation process for adsorption efficiency and adsorption capacity is as follows:

[0059] The concentration of the supernatant after adsorption was calculated based on the methylene blue standard working curve. The adsorption rate η and adsorption capacity Q of the adsorbent for the simulated methylene blue wastewater were then calculated using formulas (1) and (2). The calculation formulas are as follows:

[0060] Equation (1)

[0061] In Equation 1: η is the adsorption rate, %; C0 is the initial concentration, mg / L; C is the equilibrium concentration, mg / L.

[0062] Equation (2)

[0063] In Equation 2: Q is the adsorption capacity, mg / g; C0 is the initial concentration, mg / L; C is the equilibrium concentration, mg / L; V is the wastewater volume, L; m is the adsorbent mass, g.

[0064] The testing and characterization standards for adsorbent products are shown in Table 4 below:

[0065] Table 4

[0066] Serial Number Test Project Testing process 1 SEM test <![CDATA[Cut a piece of conductive adhesive about 0.25 cm in size and paste it on the sample stage. Use a toothpick as a tool to gently dip about 10 mg of MgO and S-MgO8 powder onto the conductive adhesive, avoiding excessive powder picking that may cause sample accumulation or equipment contamination. After attaching a sample, use an air blower to blow away the excess powder. Characterize the morphology of the sample under the working conditions of an accelerating voltage of 15 kV and a working distance of 8 mm.]] 2 <!-- 7 -->]]> ​ 2 FT-IR test <![CDATA[Turn on the instrument and preheat the light source and detector for more than 30 minutes to ensure stability. Scan air or blank matrix (such as KBr tablet) when no sample is placed to eliminate interference from CO2, water vapor, etc. in the environment. Take about 10 mg of MgO and the dried samples of S-MgO8 before and after adsorption, mix them with 100 - 200 times of KBr, grind them to a particle size of more than 200 mesh, press them into a transparent thin slice with a diameter of 13 mm and a thickness of 0.5 mm. Place the thin slice in the sample chamber, scan the spectrum, put the prepared sample into the optical path, set parameters such as wavelength range, and scan to obtain an interferogram. The instrument converts the interferogram into an infrared spectrum through Fourier transform. Use software for data analysis such as baseline correction, smoothing, peak identification and attribution analysis.]]> 3 BET test <![CDATA[Grind the MgO and S-MgO8 powder samples to particles smaller than 3 mm, weigh about 50 mg of the sample and put it into a sample tube. Then connect the sample tube to a degassing station, heat it at 120 °C and evacuate for 1-6 hours to remove the surface-adsorbed moisture and impurities. After degassing, weigh the sample tube, transfer it to a liquid nitrogen environment, measure the nitrogen adsorption amount at different pressure points by an automatic sorption analyzer, and finally calculate the specific surface area using the BET formula and analyze the pore size distribution. <!-- 8 -->]]> 4 XRD test <![CDATA[The dried samples of MgO and S-MgO8 were ground to a particle size less than 20 μm with uniform particles. Subsequently, about 50 mg of the powder was loaded into the sample cell, and the powder was densely packed and the surface was flat without a granular feeling by the tablet pressing method. Then, the sample cell was fixed on the sample stage of the diffractometer, the scanning parameters were set with a 2θ range of 5°–80° and a step size of 0.02°, and X-ray scanning was carried out to collect the diffraction pattern. Finally, background subtraction and peak searching were performed through software, and the diffraction peak positions and intensities were compared with the standard PDF card database to complete the phase identification and analysis.]]>

[0067] Example 1

[0068] This invention discloses a method for preparing a magnesium oxide adsorbent modified with silkworm sericin, comprising loading, separation, washing, and drying. The specific preparation steps are as follows:

[0069] 1) Loading: Weigh 0.8 g of dried MgO and add it to an Erlenmeyer flask. Slowly add 100 mL of sericin solution and react in a gas bath constant temperature shaker at 30-60 ℃ and 120-210 r / min for 60-240 min to ensure that magnesium oxide is evenly dispersed in the sericin solution. Through hydrogen bonding, electrostatic and other effects, sericin is fully loaded on magnesium oxide.

[0070] 2) Separation: Transfer the reaction mixture to a centrifuge tube and centrifuge at 8000 r / min for 10 min to separate the complex precipitate. Discard the supernatant and retain the precipitate.

[0071] 3) Washing: Wash the precipitate 2-3 times with deionized water to remove unreacted sericin and magnesium oxide. Centrifuge after each wash and discard the supernatant.

[0072] 4) Drying: Place the washed precipitate into an oven and dry it at 60-80 ℃ for 12-24 h. Grind the dried composite into fine powder using a mortar and pestle or a ball mill to obtain S-MgO8 adsorbent.

[0073] The preparation process of the sericin solution is as follows: 1) The dried tussah silkworm cocoon shells and 0.5% sodium carbonate solution are soaked in an Erlenmeyer flask at a volume ratio of 1:30 and the solution is obtained at 120 ℃ for 30 min; 2) After cooling to room temperature, the solution is filtered with gauze, refrigerated and stored for later use.

[0074] The testing and characterization analysis of the adsorbent obtained in Example 1 of this invention are shown in [reference needed]. Figure 1 SEM analysis, by Figure 1 It can be seen that the unmodified MgO surface is rough and loose, with many pores and no obvious shape. The S-MgO8 surface is relatively smooth and complete, with large molecules attached to it, possibly because proteins from the sericin solution were adsorbed onto the MgO. The S-MgO8+MB surface has smaller pores and a more saturated structure, possibly due to the adsorption of methylene blue molecules. (The S-MgO8 after adsorption of methylene blue is abbreviated as S-MgO8+MB). FT-IR analysis shows that... Figure 2-1 As shown, infrared spectra of MgO, S-MgO8, and S-MgO8+MB were plotted after FT-IR analysis of the data. The range is 3200-3600 cm⁻¹. -1 The corresponding broad-peak stretching vibrations are -OH and -NH2, indicating that sericin successfully modified magnesium oxide. After MB adsorption, at 1600 cm⁻¹... -1 The enhanced characteristic peak at (C=O or C=C) indicates that S-MgO8 successfully adsorbed methylene blue (MB) via electrostatic adsorption or hydrogen bonding.

[0075] BET analysis, by Figure 2-2 and Figure 2-3 After analyzing the BET test data of MgO and S-MgO8, adsorption-desorption curves of MgO and S-MgO8, and particle size distribution of S-MgO8 were plotted. The adsorption capacity of S-MgO8 was significantly higher than that of pure MgO, indicating that the modification of sericin effectively improved the adsorption capacity of MgO. At a lower P / P0, S-MgO exhibited a steeper adsorption slope, indicating that its surface contains more mesopores or active sites, which is conducive to the rapid adsorption of MB. When P / P0 approached 1.0, the adsorption capacity of S-MgO8 tended to saturate. The modification of sericin significantly enhanced the adsorption capacity and binding strength of MgO for MB by increasing surface functional groups and pore structure, which is consistent with the functional group changes such as -OH and -NH2 observed in its infrared spectrum. XRD analysis showed that... Figure 2-4The main peak is concentrated in the 10–30 nm range, corresponding to the core size of most particles, reflecting the regulatory effect of sericin modification on fine particles. A weak signal exists near 0 nm towards the small particle size end, and decreases continuously to 120 nm towards the large particle size end (above 50 nm), reflecting a certain degree of particle dispersion within the system. Overall, the modified magnesium oxide is dominated by nanoscale fine particles, while also exhibiting a wide particle size distribution.

[0076] The pore size structure parameters of the adsorbents S-MgO8 and MgO obtained in Example 1 of this invention are shown in Table 5.

[0077] Table 5

[0078] Material <![CDATA[S BET (m 2 / g)]]> <![CDATA[V pore / (cm 3 / g)]]> <![CDATA[W pore / (nm)]]> <![CDATA[S-MgO8]]> 34.1155 0.2009 23.5625 MgO 34.3441 0.2251 26.2227

[0079] Table 5 shows the pore structure parameters of S-MgO8 and MgO, where SBET is the specific surface area (m²). 2 / g), Vpore is the pore volume (cm³). 3 / g), Wpore is the average pore diameter (nm), and the average pore diameter after modification is 22.5625 nm.

[0080] The following analysis examines the effectiveness of S-MgO8 adsorbents against methylene blue under different preparation conditions.

[0081] See Figure 3The effect of sericin solution volume on adsorption efficiency was plotted using a 150 mL Erlenmeyer flask. 0.6 g of dried MgO was accurately weighed and added to the flask. Sericin solution was then slowly added in increments of 10 mL, 20 mL, 30 mL, 40 mL, 50 mL, 60 mL, 70 mL, 80 mL, 90 mL, and 100 mL. The mixture was reacted in a gas bath at 40 ℃ and 150 r / min for 120 min to ensure uniform dispersion of magnesium oxide in the sericin solution. The resulting mixture was transferred to a centrifuge tube, the complex precipitate was separated, the supernatant was discarded, and the precipitate was dried, ground, and then processed into powder. In a 100 mL volume of simulated methylene blue wastewater with a concentration of 100 mg / L, 0.2 g of S-MgO prepared under different volumes of sericin solution was accurately weighed and added. The mixture was reacted in a gas bath constant-temperature shaker at 40 ℃ and 150 r / min for 120 min. After standing for 5 min, the supernatant was aspirated with a syringe and filtered through a filter membrane using a UV756 UV-Vis spectrophotometer at a wavelength of 664 nm. The absorbance value A of the sample solution was measured. The concentration of the supernatant after adsorption was calculated based on the methylene blue standard working curve. The adsorption rate η and adsorption capacity Q of the adsorbent for the simulated methylene blue wastewater were calculated using formulas (1) and (2). The effect of different volumes of sericin solution on the adsorption effect was investigated. Figure 3 It can be seen that as the volume of the sericin solution increases, the adsorption rate and adsorption capacity of the S-MgO adsorbent for the methylene blue simulated wastewater increase significantly. The adsorption effect is best when the volume of the sericin solution is 100 mL, with an adsorption efficiency as high as 82.84% and an adsorption capacity of 41.4 mg / g. Considering the complexity of the preparation process of the sericin solution and the improvement of the adsorption effect of the methylene blue wastewater, the volume of the sericin solution was not increased further. Therefore, 100 mL of sericin solution was selected for the preparation of the S-MgO adsorbent.

[0082] See Figure 4The effect of MgO dosage on adsorption efficiency was plotted using a 150 mL Erlenmeyer flask. 0.8 g, 1.0 g, 1.2 g, and 1.5 g of dried MgO were accurately weighed and added to the flask. A suitable amount of 100 mL of sericin solution was slowly added. The mixture was reacted in a gas bath at 40 ℃ and 150 r / min for 120 min to ensure uniform dispersion of magnesium oxide in the sericin solution. The resulting mixture was transferred to a centrifuge tube, the complex precipitate was separated, the supernatant was discarded, the precipitate was dried, and the powder was ground. In 100 mL of simulated methylene blue wastewater with a concentration of 100 mg / L, 0.2000 g of S-MgO prepared with different MgO dosages was accurately weighed and added. The mixture was reacted in a gas bath constant-temperature shaker at 40 ℃ and 150 r / min for 120 min. After standing for 5 min, the supernatant was aspirated with a syringe and filtered through a filter membrane using a UV756 UV-Vis spectrophotometer set to 664 nm. The absorbance value A of the sample solution was measured. The concentration of the supernatant after adsorption was calculated based on the methylene blue standard working curve. The adsorption rate η and adsorption amount Q of the adsorbent for the simulated methylene blue wastewater were calculated using formulas (1) and (2). The effect of MgO dosage on the adsorption effect was investigated. Figure 4 It can be seen that in the first three points, as the amount of MgO added increases, the adsorption rate and adsorption capacity of S-MgO adsorbent for methylene blue simulated wastewater decrease. Taking into account the preparation quality of S-MgO adsorbent and the difference in concentration of sericin solution, MgO with an addition amount of 0.8 g is selected for the preparation of S-MgO adsorbent.

[0083] See Figure 5The effect of temperature on adsorption was plotted. A 150 mL Erlenmeyer flask was used. 0.8 g of dried MgO was accurately weighed and added to the flask, followed by a slow addition of 100 mL of sericin solution. The mixture was reacted for 120 min in a gas bath constant-temperature shaker under repeated conditions of 30 ℃, 40 ℃, 50 ℃, 60 ℃, and 150 r / min to ensure uniform dispersion of magnesium oxide in the sericin solution. The resulting mixture was transferred to a centrifuge tube, the complex precipitate was separated, the supernatant was discarded, the precipitate was retained, dried, and ground into powder. In 100 mL of simulated methylene blue wastewater with a concentration of 100 mg / L, 0.2 g of S-MgO prepared under different temperature conditions was accurately weighed and added. The mixture was reacted in a gas bath constant temperature shaker at 40 ℃ and 150 r / min for 120 min. After standing for 5 min, the supernatant was aspirated with a syringe and filtered through a filter membrane using a UV756 UV-Vis spectrophotometer set to 664 nm. The absorbance value A of the sample solution was measured. The concentration of the supernatant after adsorption was calculated based on the methylene blue standard working curve. The adsorption rate η and adsorption capacity Q of the adsorbent for the simulated methylene blue wastewater were calculated using formulas (1) and (2). The effect of temperature on the adsorption effect was investigated. Figure 5 It can be seen that the adsorption rate and adsorption capacity of S-MgO8 adsorbent for methylene blue simulated wastewater increase significantly with increasing temperature. The adsorption effect is best when the preparation temperature of the shaker is 60 ℃, with an adsorption efficiency as high as 88.00% and an adsorption capacity of 44.0 mg / g. Considering that the operating temperature of the air bath constant temperature shaker should not be too high, the experimental conditions should meet the concepts of environmental protection and high efficiency, and the increase in adsorption rate is not significant, the preparation of S-MgO8 adsorbent is carried out under the condition of a shaker temperature of 50 ℃.

[0084] See Figure 6The effect of rotation speed on adsorption efficiency was plotted. A 150 mL conical flask was used, and 0.8 g of dried MgO was accurately weighed and added to the flask. An appropriate amount of 100 mL of sericin solution was slowly added. The mixture was reacted in an air bath constant temperature shaker at 50 ℃, 120 r / min, 150 r / min, 180 r / min, and 210 r / min for 120 min to ensure uniform dispersion of magnesium oxide in the sericin solution. The resulting mixture was transferred to a centrifuge tube, the complex precipitate was separated, the supernatant was discarded, the precipitate was retained, dried, and ground into powder. In a 100 mL volume of simulated methylene blue wastewater with a concentration of 100 mg / L, 0.2 g of S-MgO prepared under different rotation speeds was accurately weighed and added. The mixture was reacted in an air bath constant-temperature shaker at 40 ℃ and 150 r / min for 120 min. After standing for 5 min, the supernatant was aspirated with a syringe and filtered through a filter membrane using a UV756 UV-Vis spectrophotometer set to 664 nm. The absorbance value A of the sample solution was measured. The concentration of the supernatant after adsorption was calculated based on the methylene blue standard working curve. The adsorption rate η and adsorption capacity Q of the adsorbent for the simulated methylene blue wastewater were calculated using formulas (1) and (2). The effect of rotation speed on the adsorption effect was investigated. Figure 6 It can be seen that as the shaking speed increases, the adsorption rate and adsorption capacity of S-MgO8 adsorbent for methylene blue simulated wastewater increase. The adsorption effect is best when the shaking speed is 210 r / min, with an adsorption efficiency as high as 89.89% and an adsorption capacity of 44.9 mg / g. Considering that the air bath constant temperature shaker equipment should not be used excessively, and that excessive speed will cause the solution to splash out, the experimental conditions should meet the concepts of environmental protection and high efficiency. Moreover, the increase in adsorption rate is not significant. Therefore, the preparation of S-MgO8 adsorbent was carried out under the condition of shaking speed of 180 r / min.

[0085] See Figure 7The effect of preparation time on adsorption efficiency was plotted using a 150 mL Erlenmeyer flask. 0.8 g of dried MgO was accurately weighed and added to the flask, followed by a slow addition of 100 mL of sericin solution. The mixture was reacted in a gas bath at 50 ℃ and 180 r / min for 60 min, 120 min, 180 min, and 210 min to ensure uniform dispersion of magnesium oxide in the sericin solution. The resulting mixture was transferred to a centrifuge tube, the complex precipitate was separated, the supernatant was discarded, and the precipitate was dried, ground, and then processed into powder. In 100 mL of simulated methylene blue wastewater with a concentration of 100 mg / L, 0.2 g of S-MgO prepared at different times was accurately weighed and added. The mixture was reacted in a gas bath constant-temperature shaker at 40 ℃ and 150 r / min for 120 min. After standing for 5 min, the supernatant was aspirated using a syringe at a wavelength of 664 nm on a UV756 UV-Vis spectrophotometer and filtered through a filter membrane. The absorbance value A of the sample solution was measured. The effect of preparation time on the adsorption effect was investigated. Figure 7 It is known that as the preparation time increases, the adsorption rate and adsorption capacity of S-MgO8 adsorbent for methylene blue simulated wastewater do not increase significantly. The adsorption effect is already saturated at 180 min, with an adsorption efficiency as high as 89.9% and an adsorption capacity of 44.9 mg / g. Considering the time cost and the fact that the adsorption rate tends to increase more slowly with longer preparation time, a preparation time of 180 min was selected as the condition for preparing S-MgO8 adsorbent.

[0086] See Figure 8 The effect curve of S-MgO8 dosage on adsorption effect was obtained. A 150 mL conical flask was used to add 100 mL of methylene blue simulated wastewater with a concentration of 100 mg / L. 0.0500 g, 0.0800 g, 0.1000 g, 0.1200 g, 0.1500 g, and 0.2000 g of S-MgO8 were accurately weighed and added to the conical flask. The mixture was reacted in a gas bath constant temperature shaker at 40 ℃ and 150 r / min for 120 min. After standing for 5 min, the wavelength was set to 664 nm in a UV756 ultraviolet-visible spectrophotometer. The supernatant was aspirated with a syringe and filtered through a filter membrane. The absorbance value A of different adsorbent dosages was measured. The concentration of the supernatant after adsorption was calculated according to the methylene blue standard working curve. The adsorption rate η and adsorption amount Q of the adsorbent for the methylene blue simulated wastewater were calculated using formulas (1) and (2). The effect of S-MgO dosage on adsorption efficiency. Figure 8It can be seen that with the increase of S-MgO8 dosage, the adsorption rate and adsorption capacity of the adsorbent for methylene blue simulated wastewater significantly increased. The adsorption effect was best when the S-MgO8 dosage was 0.2000 g, with an adsorption efficiency as high as 90.30% and an adsorption capacity of 45.1 mg / g. Therefore, an S-MgO8 dosage of 0.2000 g was selected for adsorption of methylene blue wastewater.

[0087] See Figure 9 The effect curve of adsorption time on adsorption effect was plotted. A 150 mL conical flask was used, and 100 mL of methylene blue simulated wastewater with a concentration of 100 mg / L was added. 0.2000 g of S-MgO8 was accurately weighed and added to the conical flask. The mixture was reacted in a gas bath constant temperature shaker at 40℃ and 150 r / min for 30 min, 60 min, 90 min, 120 min, and 150 min. After standing for 5 min, the wavelength was set to 664 nm in a UV756 ultraviolet-visible spectrophotometer. The supernatant was taken with a syringe and filtered through a filter membrane. The absorbance value A at different adsorption times was measured. The concentration of the supernatant after adsorption was calculated according to the methylene blue standard working curve. The adsorption rate η and adsorption amount Q of the adsorbent for the methylene blue simulated wastewater were calculated by formulas (1) and (2). The effect of adsorption time on adsorption effect was calculated by... Figure 9 It can be seen that as the adsorption time increases, the adsorption effect of S-MgO8 adsorbent on methylene blue gradually increases, and the adsorption force is strongest at 60 min, with an adsorption rate of up to 91%. Desorption will occur after 60 min. Therefore, the optimal adsorption time is 60 min.

[0088] See Figure 10 The present invention presents a curve illustrating the effect of the number of regeneration cycles on the regeneration efficiency of S-MgO8. The regeneration experimental process involves drying and weighing the S-MgO8 powder after the first adsorption of methylene blue wastewater (mass m1), placing it in a small beaker, adding distilled water at a volume ratio of 30:1 (m1 to distilled water volume), magnetically stirring for 10 min to remove loosely adsorbed dye. After pouring out the surface solution, adding 80% anhydrous ethanol solution at a volume ratio of 30:1 (m1 to anhydrous ethanol volume), stirring thoroughly, and then placing the mixture in a 40°C ultrasonic cleaner for desorption treatment for 40 min. The resulting mixture is transferred to a centrifuge tube and centrifuged at 4000 r / min for 5 min to separate the precipitate. The supernatant is discarded, and the precipitate is retained and washed 2-3 times with distilled water until the solution is nearly colorless. This process is repeated three times, and after three washes, the precipitate is dried in an oven and weighed (mass m2) for adsorption experiments. The regeneration is performed three times.

[0089] Depend on Figure 10It can be seen that after adsorption of the adsorbent with different regeneration cycles, the regeneration effect can be analyzed based on the adsorption rate. In the three regeneration cycles, the overall regeneration efficiency shows a trend of first increasing and then decreasing. The efficiency is significantly improved after the first regeneration, but gradually decreases in subsequent cycles, indicating that the adsorbent performance degrades with repeated use. The mass recovery rate is relatively low, approximately 60%-80%, possibly because the adsorbent becomes lighter due to ethanol decolorization during regeneration; while the adsorption capacity recovery rate remains high, close to 120%-140%, indicating that some active sites remain effective after regeneration or that methylene blue is completely desorbed, leading to enhanced adsorption capacity. In summary, although this adsorbent possesses certain regeneration potential...

[0090] This invention provides a comparative analysis of the adsorption effects of S-MgO8 on other dye wastewater. By performing a full-spectrum scan of simulated wastewater containing four dyes—carmine, methyl orange, reactive red, and methylene blue—adsorbed by S-MgO8, the selectivity of S-MgO8 was analyzed. The results showed that S-MgO8 exhibited the most significant color change for reactive red, a large-molecule anionic dye. The characteristic absorption peak intensities of carmine and methyl orange decreased. In conclusion, S-MgO8 can be applied to the adsorption of various dyes and has high application value.

[0091] See Figure 11 Take a 150 mL conical flask, add 100 mL of carmine simulated wastewater with a concentration of 100 mg / L, accurately weigh 2.000 g of S-MgO8 and add it to the conical flask. React in an air bath constant temperature shaker at 40 ℃ and 150 r / min for 0 min, 30 min and 60 min. After standing for 5 min, use a syringe to draw up the supernatant and filter it with a filter membrane. Scan the full spectrum wavelength of carmine at different adsorption times, measure the absorbance at different wavelengths, and make a full spectrum of carmine.

[0092] See Figure 12 Take a 150 mL conical flask, add 100 mL of methyl orange simulated wastewater with a concentration of 100 mg / L, accurately weigh 2.000 g of S-MgO8 and add it to the conical flask. React in an air bath constant temperature shaker at 40 ℃ and 150 r / min for 0 min, 30 min and 60 min. After standing for 5 min, use a syringe to draw up the supernatant and filter it with a filter membrane. Scan the full spectrum wavelength of methyl orange at different adsorption times, measure the absorbance at different wavelengths, and make a full spectrum of methyl orange.

[0093] See Figure 13For the adsorption experiment of Reactive Red, a 150 mL Erlenmeyer flask was used, and 100 mL of simulated wastewater with a concentration of 100 mg / L Reactive Red was added. 2.000 g of S-MgO8 was accurately weighed and added to the Erlenmeyer flask. The mixture was reacted in an air bath constant temperature shaker at 40 ℃ and 150 r / min for 0 min, 30 min, and 60 min. After standing for 5 min, the supernatant was aspirated with a syringe and filtered through a filter membrane. The full spectrum wavelength of Reactive Red at different adsorption times was scanned, and the absorbance at different wavelengths was measured to plot the full spectrum of Reactive Red.

[0094] Example 2

[0095] This invention discloses a method for preparing a magnesium oxide adsorbent modified with silkworm sericin, comprising loading, separation, washing, and drying. The specific preparation steps are as follows:

[0096] 1) Loading: Weigh 1.0 g of dried MgO and add it to an Erlenmeyer flask. Slowly add 100 mL of sericin solution and react in an air bath constant temperature shaker at 30-60 ℃ and 120-210 r / min for 60-240 min to ensure that magnesium oxide is evenly dispersed in the sericin solution and that sericin is fully loaded on magnesium oxide.

[0097] 2) Separation: Transfer the reaction mixture to a centrifuge tube and centrifuge at 8000 r / min for 10 min to separate the complex precipitate. Discard the supernatant and retain the precipitate.

[0098] 3) Washing: Wash the precipitate 2-3 times with deionized water to remove unreacted sericin and magnesium oxide. Centrifuge after each wash and discard the supernatant.

[0099] 4) Drying: Place the washed precipitate in an oven and dry at 60-80 ℃ for 12-24 h. Grind the dried complex into a fine powder using a mortar and pestle or a ball mill to obtain S-MgO. 10 Adsorbent.

[0100] The preparation process of the sericin solution is as follows: 1) The dried tussah silkworm cocoon shells and 0.5% sodium carbonate solution are soaked in an Erlenmeyer flask at a volume ratio of 1:30 and the solution is obtained at 120 ℃ for 30 min; 2) After cooling to room temperature, the solution is filtered with gauze, refrigerated and stored for later use.

[0101] The following analysis examines the S-MgO obtained under different preparation conditions. 10 Analysis of the effect of adsorbent on methylene blue.

[0102] See Figure 14The effect of sericin solution volume on adsorption efficiency is shown in the curve. The experimental procedure is as follows: Figure 3 The only change was that the amount of MgO added after drying was 1.0 g, while the rest of the process remained the same. Figure 14 It can be seen that as the volume of the sericin solution increases, S-MgO 10 The adsorption rate and adsorption capacity of the adsorbent for methylene blue simulated wastewater were significantly increased. The best adsorption effect was observed when the volume of the sericin solution was 100 mL, with an adsorption efficiency of 80.04% and an adsorption capacity of 40.0 mg / g. Subsequent experiments used 100 mL of sericin solution to prepare S-MgO. 10 Adsorbent.

[0103] See Figure 15 The effect of temperature on adsorption efficiency is shown in the graph. The experimental procedure is as follows: Figure 5 The only change was that the amount of MgO added after drying was 1.0 g, while the rest of the process remained the same. Figure 15 It can be seen that as the temperature increases, S-MgO 10 The adsorption rate and adsorption capacity of the adsorbent for methylene blue simulated wastewater were significantly increased. The best adsorption effect was observed at a preparation temperature of 60 ℃ in the shaker, with an adsorption efficiency of 88.00% and an adsorption capacity of 42.5 mg / g. Compared with 50 ℃, the improvement was not significant. Considering energy conservation and environmental protection, the preparation of S-MgO was carried out at a shaker temperature of 50 ℃. 10 Adsorbent.

[0104] See Figure 16 The effect of rotation speed on adsorption efficiency is shown in the graph. The experimental procedure is as follows: Figure 6 The only change was that the amount of MgO added after drying was 1.0 g, while the rest of the process remained the same. Figure 16 It can be seen that as the shaking speed increases, S-MgO 10 The adsorption rate and adsorption capacity of the adsorbent for methylene blue simulated wastewater increased, with the best adsorption effect at a shaker speed of 210 r / min, reaching an adsorption efficiency of 86.39% and an adsorption capacity of 43.1 mg / g. Considering that the air bath constant temperature shaker equipment should not be used excessively, and that excessive speed would cause solution splashing, the experimental conditions should meet the principles of environmental protection and high efficiency. Furthermore, the increase in adsorption rate was not significant. Therefore, the preparation of S-MgO was carried out at a shaker speed of 180 r / min. 10 Adsorbent.

[0105] See Figure 17 The effect of preparation time on adsorption effect is shown in the curve. The experimental procedure is as follows: Figure 7 The only change was that the amount of MgO added after drying was 1.0 g, while the rest of the process remained the same. Figure 17 It is known that as the preparation time increases, S-MgO 10The adsorbent did not significantly increase the adsorption rate and adsorption capacity of the methylene blue simulated wastewater. Adsorption saturated at 180 min, with an adsorption efficiency of 85.50% and an adsorption capacity of 42.7 mg / g. Considering the time cost and the fact that the increase in adsorption rate tends to plateau with longer preparation times, a preparation time of 180 min was chosen for the preparation of S-MgO. 10 Adsorbent.

[0106] See Figure 18 S-MgO 10 The curve showing the effect of dosage on adsorption efficiency is shown in the figure. The experimental procedure is as follows: Figure 8 The adsorbent added is S-MgO 10 The rest of the process remains unchanged. From Figure 18 It can be seen that, with the development of S-MgO 10 Increasing the dosage significantly improved the adsorption rate and adsorption capacity of the adsorbent for the methylene blue simulated wastewater, particularly in S-MgO. 10 The adsorption effect was best when the dosage was 0.2000 g, with an adsorption efficiency as high as 87.50% and an adsorption capacity of 44.2 mg / g. Therefore, S-MgO was selected. 10 The methylene blue wastewater was adsorbed at a dosage of 0.2000 g.

[0107] See Figure 19 The effect of adsorption time on adsorption efficiency is shown in the graph. The experimental procedure is as follows: Figure 9 The adsorbent added is S-MgO 10 The rest of the process remains unchanged. From Figure 19 It can be seen that with the increase of adsorption time, S-MgO 10 The adsorption effect of the adsorbent on methylene blue gradually increases, with the strongest adsorption force at 60 min and an adsorption rate of up to 88.5%. Desorption will occur after 60 min. Therefore, the optimal adsorption time is 60 min.

[0108] Example 3

[0109] This invention discloses a method for preparing a magnesium oxide adsorbent modified with silkworm sericin, comprising loading, separation, washing, and drying. The specific preparation steps are as follows:

[0110] 1) Loading: Weigh 1.5 g of dried MgO and add it to an Erlenmeyer flask. Slowly add 100 mL of sericin solution and react in a gas bath constant temperature shaker at 30-60 ℃ and 120-210 r / min for 60-240 min to ensure that magnesium oxide is evenly dispersed in the sericin solution. Through hydrogen bonding, electrostatic and other effects, sericin is fully loaded on magnesium oxide.

[0111] 2) Separation: Transfer the reaction mixture to a centrifuge tube and centrifuge at 8000 r / min for 10 min to separate the complex precipitate. Discard the supernatant and retain the precipitate.

[0112] 3) Washing: Wash the precipitate 2-3 times with deionized water to remove unreacted sericin and magnesium oxide. Centrifuge after each wash and discard the supernatant.

[0113] 4) Drying: Place the washed precipitate in an oven and dry at 60-80 ℃ for 12-24 h. Grind the dried complex into a fine powder using a mortar and pestle or a ball mill to obtain S-MgO. 15 Adsorbent.

[0114] The preparation process of the sericin solution is as follows: 1) The dried tussah silkworm cocoon shells and 0.5% sodium carbonate solution are soaked in an Erlenmeyer flask at a volume ratio of 1:30 and the solution is obtained at 120 ℃ for 30 min; 2) After cooling to room temperature, the solution is filtered with gauze, refrigerated and stored for later use.

[0115] The following analysis examines the S-MgO obtained under different preparation conditions. 15 Analysis of the effect of adsorbent on methylene blue.

[0116] See Figure 20 The effect of sericin solution volume on adsorption efficiency is shown in the curve. The experimental procedure is as follows: Figure 3 The only change was that the amount of MgO added after drying was 1.5 g, while the rest of the process remained the same. Figure 20 It can be seen that as the volume of the sericin solution increases, S-MgO 15 The adsorption rate and adsorption capacity of the adsorbent for methylene blue simulated wastewater were significantly increased. The best adsorption effect was observed when the volume of the sericin solution was 100 mL, with an adsorption efficiency of 75.10% and an adsorption capacity of 36.7 mg / g. Subsequent experiments used 100 mL of sericin solution to prepare S-MgO. 15 Adsorbent.

[0117] See Figure 21 The effect of temperature on adsorption efficiency is shown in the graph. The experimental procedure is as follows: Figure 5 The only change was that the amount of MgO added after drying was 1.5 g, while the rest of the process remained the same. Figure 21 It can be seen that as the temperature increases, S-MgO 15 The adsorption rate and adsorption capacity of the adsorbent for methylene blue simulated wastewater were significantly increased. The best adsorption effect was observed at a preparation temperature of 60 ℃ in the shaker, with an adsorption efficiency of 76.00% and an adsorption capacity of 37.5 mg / g. Compared with 50 ℃, the improvement was not significant. Considering energy conservation and environmental protection, the preparation of S-MgO was carried out at a shaker temperature of 50 ℃. 15 Adsorbent.

[0118] See Figure 22 The effect of rotation speed on adsorption efficiency is shown in the graph. The experimental procedure is as follows: Figure 6 The only change was that the amount of MgO added after drying was 1.5 g, while the rest of the process remained the same. Figure 22 It can be seen that as the shaking speed increases, S-MgO 15 The adsorption rate and adsorption capacity of the adsorbent for methylene blue simulated wastewater increased, with the best adsorption effect observed at a shaking speed of 210 r / min, achieving an adsorption efficiency of up to 76.39% and an adsorption capacity of 38.1 mg / g. Considering environmental protection and high efficiency, the preparation of S-MgO was carried out at a shaking speed of 180 r / min. 15 Adsorbent.

[0119] See Figure 23 The effect of preparation time on adsorption effect is shown in the curve. The experimental procedure is as follows: Figure 7 The only change was that the amount of MgO added after drying was 1.5 g, while the rest of the process remained the same. Figure 23 It is known that as the preparation time increases, S-MgO 15 The adsorbent did not significantly increase the adsorption rate and adsorption capacity of the methylene blue simulated wastewater. Adsorption saturated at 180 min, with an adsorption efficiency of 80.50% and an adsorption capacity of 40.2 mg / g. Considering the time cost and the fact that the increase in adsorption rate tends to plateau with longer preparation times, a preparation time of 180 min was chosen for the preparation of S-MgO. 15 Adsorbent.

[0120] See Figure 24 S-MgO 15 The curve showing the effect of dosage on adsorption efficiency is shown in the figure. The experimental procedure is as follows: Figure 8 The adsorbent added is S-MgO 15 The rest of the process remains unchanged. From Figure 24 It can be seen that, with the development of S-MgO 15 Increasing the dosage significantly improved the adsorption rate and adsorption capacity of the adsorbent for the methylene blue simulated wastewater, particularly in S-MgO. 15 The adsorption effect was best when the dosage was 0.2000 g, with an adsorption efficiency as high as 80.80% and an adsorption capacity of 40.3 mg / g. Therefore, S-MgO was selected. 15 The methylene blue wastewater was adsorbed at a dosage of 0.2000 g.

[0121] See Figure 25 The effect of adsorption time on adsorption efficiency is shown in the graph. The experimental procedure is as follows: Figure 9 The adsorbent added is S-MgO 15 The rest of the process remains unchanged. From Figure 25It can be seen that with the increase of adsorption time, S-MgO 15 The adsorption effect of the adsorbent on methylene blue gradually increases, with the strongest adsorption force at 60 min and an adsorption rate of up to 81.4%. Desorption will occur after 60 min. Therefore, the optimal adsorption time is 60 min.

[0122] Depend on Figures 21-25 It can be seen that, using S-MgO 15 The adsorption rate and adsorption capacity of the adsorbents on methylene blue simulated wastewater under different conditions are compared with those of S-MgO8 and S-MgO. 10 The pattern is the same, but as the amount of MgO added increases while the amount of sericin solution remains constant, the number of active sites in sericin decreases, thus reducing the number of adsorption sites for the composite adsorbent. Therefore, S-MgO... 15 The adsorbent exhibited the lowest adsorption rate and capacity for methylene blue, with adsorption performance lower than that of S-MgO8 and S-MgO. 10 .

Claims

1. A method for preparing a magnesium oxide adsorbent modified with tussah silk fibroin, characterized in that, The preparation steps include loading, separation, cleaning, and drying, and are as follows: 1) Loading: Weigh 0.8-1.5 g of dried MgO and add it to an Erlenmeyer flask. Slowly add 100 mL of sericin solution and react in a gas bath constant temperature shaker at 50 ℃ and 180 r / min for 180 min to ensure that magnesium oxide is uniformly dispersed in the sericin solution and that the sericin is fully loaded on the magnesium oxide. The sericin solution is the wastewater generated by tussah silkworm silk production enterprises during the cocoon boiling process, which uses a volume ratio of cocoon shell to 0.5% sodium carbonate solution of 1:

30. 2) Separation: Transfer the reaction mixture to a centrifuge tube and centrifuge at 8000 r / min for 10 min to separate the complex precipitate. Discard the supernatant and retain the precipitate. 3) Washing: Wash the precipitate 2-3 times with deionized water to remove unreacted sericin and magnesium oxide. Centrifuge after each wash and discard the supernatant. 4) Drying: Place the washed precipitate into an oven and dry it at 60-80 ℃ for 12-24 h. Grind the dried composite into fine powder using a mortar and pestle or a ball mill to obtain S-MgO adsorbent.

2. The application of the adsorbent prepared by the method for preparing magnesium oxide adsorbent modified with silkworm fibroin according to claim 1, characterized in that, The S-MgO adsorbent is used to adsorb methylene blue, carmine, methyl orange or reactive red dyes. The amount of adsorbent added is 0.15 g-0.2 g / 100 mL of dye-simulated wastewater, and the concentration of dye-simulated wastewater is 100 mg / L.

3. The application of the adsorbent prepared by the method for preparing magnesium oxide adsorbent modified with silkworm fibroin according to claim 2, characterized in that, The S-MgO adsorbent achieved an adsorption rate of 90.30% at 40 °C, 150 r / min, an S-MgO adsorbent dosage of 0.2 g, an initial methylene blue concentration of 100 mg / L, a treatment volume of 100 mL, and a shaking time of 60 min.

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