Dechlorinating agent, preparation method thereof and application of dechlorinating agent in grease dechlorination

Abstract

The invention discloses a dechlorinating agent, a preparation method thereof and application of the dechlorinating agent in grease dechlorination, and belongs to the technical field of grease treatment. According to the technical scheme, the method comprises the following steps: dispersing a Fe3O4-coated SiO2 carrier into deionized water, adding into a methanol and glycerol mixed solution, removing oxygen, carrying out ultrasonic dispersion, adding ammonia water, adding a sulfydryl silane coupling agent, introducing inert gas into a reaction system, sealing, heating to 50-90 DEG C, reacting, washing and drying after the reaction is finished, so as to obtain an adsorbent Fe3O4-coated SiO2-SH, namely the dechlorinating agent. The method is applied to the aspect of grease dechlorination, solves the problem that chlorine impurities in existing waste grease cannot be effectively treated, and then serious corrosion is caused to equipment and pipelines, and has the characteristics that the preparation process is simple and easy to operate, and the prepared dechlorination agent can effectively reduce the content of organic chlorine in grease.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil processing, and particularly relates to a dechlorination agent, a preparation method thereof and application of the dechlorination agent in oil dechlorination. BACKGROUND

[0002] With the enhancement of environmental awareness and the popularization of resource recycling concept, the resource utilization of waste oil has become a research hotspot. The waste oil is converted into alkane liquid fuel through catalytic hydrogenation and isomerization, as a second-generation biodiesel raw material, which has a significant cost advantage, can effectively reduce the dependence on petrochemical diesel, and can reduce the pollution of waste to the environment, and is one of the important ways to realize sustainable development.

[0003] However, chlorine impurities are generally present in waste oil. These chlorine-containing compounds can cause serious corrosion problems to equipment and pipelines. In low temperature environment, chlorine-containing waste oil can corrode metal materials and destroy the protective film on the surface of the metal; and in high temperature working condition, the corrosion will be further intensified. Especially in the hydrogenation deoxygenation process in the subsequent production of SAF, hydrogen chloride and water molecules will form hydrochloric acid, causing a local strong acid corrosion environment, which is more serious to the equipment.

[0004] At present, the treatment of organic chlorine in waste oil is still a difficult problem to be solved. SUMMARY

[0005] In view of the deficiencies in the prior art, the technical problem to be solved by the present application is to overcome the fact that the chlorine impurities in the existing waste oil cannot be effectively treated, which will cause serious corrosion problems to the equipment and pipelines, and to provide a dechlorination agent with simple preparation process and easy operation, which can effectively reduce the content of organic chlorine in oil, a preparation method thereof and application of the dechlorination agent in oil dechlorination.

[0006] To solve the technical problem, the technical scheme adopted by the present application is: The present application provides a preparation method of a dechlorination agent, comprising: Step 1: Dissolve ferric chloride and ferrous chloride in a polyethylene glycol solution to form solution A; add ammonia water to the polyethylene glycol, stir uniformly and remove oxygen to form a mixed solution B; under the action of ultrasonic waves, add solution A dropwise to mixed solution B, after the dropwise addition is completed, react at 50-80 DEG C, and the reaction process is protected by nitrogen and ultrasonic waves, after the reaction is completed, separate, wash and dry to obtain magnetic ferroferric oxide particles; Step 2: take the magnetic magnetite particles and add them to deionized water to form a dispersion liquid C; dissolve tetraethyl orthosilicate in anhydrous ethanol to form a mixed liquid D; mix the dispersion liquid C and the mixed liquid D and ultrasonically stir, then dropwise add ammonia water, continue to ultrasonically stir at 30-50 DEG C, after the reaction is completed, separate, wash, and dry to obtain a Fe3O4@SiO2 carrier; Step 3: take the Fe3O4@SiO2 carrier and disperse it in deionized water, add a mixed solution of methanol and glycerol, deoxygenate and ultrasonically disperse, then add ammonia water, and then add a mercapto silane coupling agent, after the addition is completed, the reaction system is sealed by filling with an inert gas, heated to 50-90 DEG C, and reacted, after the reaction is completed, washed and dried to obtain an adsorbent Fe3O4@SiO2-SH, i.e., a chlorine removal agent.

[0007] In some embodiments, the volume ratio of tetraethyl orthosilicate to anhydrous ethanol in the mixed liquid D is 1:50-200.

[0008] In some embodiments, the power of the ultrasonic is 450-600 W.

[0009] In some embodiments, the molar ratio of Fe 2+ to Fe 3+ in the solution A is 1:2.

[0010] In some embodiments, in step 2, the molar ratio of Fe in the magnetic magnetite particles to Si in the tetraethyl orthosilicate is 5-20:1-5.

[0011] In some embodiments, in step 3, the weight ratio of the amount of the mercapto silane coupling agent added to the Fe3O4@SiO2 carrier is 0.1-1:1.

[0012] In some embodiments, the mercapto silane coupling agent is 3-mercaptopropyl trimethoxysilane.

[0013] In some embodiments, the reaction temperature of step 1 is 50-80 DEG C, and the reaction time is 1-3 h; the reaction temperature of step 2 is 30-50 DEG C, and the reaction time is 2-8 h; and the reaction temperature of step 3 is 50-90 DEG C, and the reaction time is 2-10 h.

[0014] Another aspect of the present application provides a chlorine removal agent prepared by the preparation method of the chlorine removal agent according to any one of the technical solutions described above.

[0015] The present application also provides the application of the above-mentioned chlorine removal agent in oil and fat dechlorination.

[0016] Compared with the prior art, the present application has the following beneficial effects: This invention provides a method for preparing a dechlorinating agent. The preparation process is simple and easy to operate. The method uses ultrasonic cavitation to break up magnetic core agglomerates and uses low silicon source concentration for directional coating to control the particle size of the adsorbent. The prepared dechlorinating agent can effectively reduce the organic chlorine content in oils and greases. Moreover, the dechlorinating agent is magnetically endowed with Fe3O4 cores, and after adsorption, it can be quickly separated by an external magnetic field, which is convenient for recycling. Attached Figure Description

[0017] Figure 1 The BET diagram of the Fe3O4@SiO2 support provided in Example 1 of this invention; Figure 2 The BET diagram is shown for the dechlorination agent provided in Example 1 of this invention; Figure 3 This is the BET diagram of the dechlorination agent provided in Comparative Example 2 of the present invention; Figure 4 This is a SEM image of the dechlorinating agent provided in Example 1 of the present invention; Figure 5 This is a SEM image of the dechlorinating agent provided in Comparative Example 4 of the present invention; Figure 6 This is a SEM image of the dechlorination agent provided in Comparative Example 2 of the present invention. Detailed Implementation

[0018] The technical solutions in specific embodiments of the present invention will be described in detail and completely below. Obviously, the described embodiments are only some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0019] This invention provides a method for preparing a dechlorinating agent, comprising the following steps: 1. Dissolving ferric chloride and ferrous chloride in a polyethylene glycol solution to form solution A; 2. Adding ammonia water to the polyethylene glycol and stirring until homogeneous to remove oxygen, forming a mixed solution B; 3. Under an ultrasonic environment, adding solution A dropwise to the mixed solution B; 4. After the addition is complete, reacting at 50-80°C, with nitrogen protection and ultrasonication maintained during the reaction; 5. After the reaction is complete, separating, washing, and drying to obtain magnetic iron oxide particles.

[0020] In step 1, solution A is added dropwise to mixed solution B, resulting in high particle size uniformity and instantaneous nucleation dominating. Specifically: when Fe... 2+ / Fe 3+ When a strong alkali is added to the mixture, a localized high supersaturation is reached instantaneously, resulting in explosive nucleation and the generation of a large number of crystal nuclei, which inhibits subsequent growth and yields small-sized particles. Step 1 also limits the continuous sonication of the reaction process, which is beneficial for using cavitation effect to break up agglomerates and reduce aggregation.

[0021] The application provides a preparation method of a dechlorination agent, comprising the following steps: 2, adding magnetic Fe3O4 particles into deionized water to form a dispersion liquid C by ultrasonic treatment; dissolving tetraethyl orthosilicate in anhydrous ethanol to form a mixed liquid D; mixing the dispersion liquid C and the mixed liquid D and stirring by ultrasonic treatment, then adding ammonia water dropwise, and continuing to stir by ultrasonic treatment at 30-50 DEG C; after the reaction is completed, separating, washing and drying to obtain a Fe3O4@SiO2 carrier.

[0022] The application provides a preparation method of a dechlorination agent, comprising the following steps: 3, dispersing the Fe3O4@SiO2 carrier into deionized water, adding a mixed solution of methanol and glycerol, removing oxygen and dispersing by ultrasonic treatment, then adding ammonia water and a thiol-containing silane coupling agent, after the addition is completed, sealing the reaction system by filling with inert gas, heating to 50-90 DEG C for reaction, and after the reaction is completed, washing and drying to obtain an adsorbent Fe3O4@SiO2-SH, namely the dechlorination agent.

[0023] The preparation method has simple preparation process and easy operation, the magnetic core agglomerates are broken by ultrasonic cavitation, the particle size of the adsorbent is controlled by low-silicon source concentration directional coating, the Fe3O4@SiO2 is modified by thiol, on one hand, the hydrophobicity of the Fe3O4@SiO2 is changed from hydrophilicity to hydrophobicity, and better 'hydrophobic matching' is formed with organic chlorine compounds in oil and fat (mostly fat-soluble), the hydrophobic interaction can promote the diffusion of the organic chlorine molecules from the oil and fat to the surface of the adsorbent, and the adsorption efficiency is improved; on the other hand, the thiol can chemically adsorb the organic chlorine by coordination, nucleophilic substitution and the like, and can physically adsorb the organic chlorine by forming a hydrogen bond between the hydrogen atom in the thiol and the chlorine atom in the organic chlorine molecule, and the adsorption effect is improved by chemical and physical double adsorption.

[0024] The magnetic adsorbent modified by thiol can be prepared by the preparation method, is beneficial to recovery, is not easy to block, and when the adsorbent is applied to the dechlorination agent for oil and fat, the content of the organic chlorine in the oil and fat can be effectively reduced, the preparation process is simple and easy to operate, the product can be recycled, the cost is low, and the application is more suitable for industrialization promotion and application.

[0025] In some embodiments, the volume ratio of the tetraethyl orthosilicate to the anhydrous ethanol in the mixed liquid D is 1:50-200. It can be understood that the volume ratio of the tetraethyl orthosilicate to the anhydrous ethanol in the mixed liquid D can also be 1:65, 1:80, 1:95, 1:105, 1:120, 1:135, 1:150, 1:165, 1:180, 1:195 and any point value ratio in the range thereof.

[0026] In some embodiments, the power of the ultrasound is 450-600 W. It can be appreciated that the power of the ultrasound can also be 500 W, 550 W, and any point value within the range thereof.

[0027] The purpose of using ultrasound and low silicon source concentration in the above preparation process is to disperse the magnetic core agglomerates, prevent agglomeration, activate the particle surface through cavitation effect, enhance the activity of silicon hydroxyl, promote the mass transfer of silicon source hydrolysis and condensation, refine the structure of the coating layer, and uniformly load silicon on the magnetic core.

[0028] In some embodiments, the molar ratio of Fe 2+ and Fe 3+ in solution A is 1:2.

[0029] In some embodiments, in step 2, the molar ratio of Fe in the magnetic ferroferric oxide particles to Si in the tetraethyl orthosilicate is 5-20:1-5.

[0030] In some embodiments, in step 3, the weight ratio of the amount of the mercapto silane coupling agent added to the Fe3O4@SiO2 carrier is 0.1-1:1. It can be appreciated that the weight ratio of the amount of the mercapto silane coupling agent added to the Fe3O4@SiO2 carrier can also be 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, and any point value within the range thereof.

[0031] In some embodiments, the mercapto silane coupling agent is 3-mercaptopropyl trimethoxysilane.

[0032] In some embodiments, the reaction temperature of step 1 is 50-80°C, and the reaction time is 1-3 h; the reaction temperature of step 2 is 30-50°C, and the reaction time is 2-8 h; and the reaction temperature of step 3 is 50-90°C, and the reaction time is 2-10 h. It can be appreciated that the reaction temperature of step 1 can also be 55°C, 60°C, 65°C, 70°C, 75°C, and any point value within the range thereof, and the reaction time can also be 1.5 h, 2.0 h, 2.5 h, and any point value within the range thereof; the reaction temperature of step 2 can also be 35°C, 40°C, 45°C, and any point value within the range thereof, and the reaction time can also be 3 h, 4 h, 5 h, 6 h, 7 h, and any point value within the range thereof; and the reaction temperature of step 3 can also be 60°C, 70°C, 80°C, and any point value within the range thereof, and the reaction time can also be 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, and any point value within the range thereof.

[0033] Another aspect of the present application provides a method for preparing the above-mentioned dechlorination agent.

[0034] The above-mentioned dechlorination agent can efficiently contact: has a high specific surface area and a mesoporous structure, ensuring that there is still a large enough internal and external surface for chlorinated compounds to contact in high-viscosity oil; The above-mentioned dechlorination agent has strong adsorption / reaction: the surface modified sulfhydryl (-SH) specifically and efficiently captures complex chlorinated compounds (especially organic chlorine) in oil through strong nucleophilic substitution or coordination, and the reaction mechanism does not depend on the water environment; The above-mentioned dechlorination agent has selective anti-interference: the high affinity of sulfhydryl for chlorinated compounds provides a certain selectivity, reducing the competitive adsorption of a large number of coexisting components in oil, and the mesoporous structure is relatively difficult to be blocked by macromolecular impurities; The above-mentioned dechlorination agent is convenient to separate: the superparamagnetic property provided by the Fe3O4 core enables rapid and complete solid-liquid separation after reaction by simply applying a magnetic field, overcoming the separation problem caused by the high viscosity of oil; The above-mentioned dechlorination agent is stable and durable: the SiO2 shell protects the magnetic core and improves the chemical stability of the material in the oil environment.

[0035] The present application also provides the above-mentioned dechlorination agent for use in oil dechlorination.

[0036] Compared with water treatment and other scenarios, oil is a high-viscosity, non-polar or weakly polar organic liquid, which leads to: 1. Large mass transfer resistance: chlorinated compounds (whether organic chlorine or inorganic chloride salts) diffuse much slower in oil than in water. Chlorinated compounds need to overcome greater resistance to migrate to the surface of the dechlorination agent; 2. Difficulty in dispersing hydrophilic adsorbents: Many efficient dechlorination agents (such as certain ion exchange resins, activated alumina) are hydrophilic and difficult to disperse uniformly in hydrophobic oil, which can easily agglomerate, greatly reducing the effective contact area; 3. Chlorine in oil may come not only from residual inorganic chlorides (such as NaCl, MgCl2), but also more commonly and harmfully from organic chlorides, such as chlorinated fatty acid esters, pesticide residues (such as lindane, DDT and their metabolites), etc. These organic chlorinated compounds usually have large molecular sizes and hydrophobicity, and the chemical bond (C-Cl bond) is much stronger than that of inorganic chloride ions (Cl -) are more stable and difficult to be removed; and the oil and fat contains a large amount of other components, such as free fatty acid (FFA), triglyceride, phospholipid, pigment (chlorophyll, carotenoid), sterol, tocopherol (VE) and oxidation products (aldehyde, ketone, acid), which can also interact with the active sites of the dechlorination agent (such as hydrogen bond, van der Waals force, and even chemical reaction), compete with the target chlorinated compounds for the limited adsorption sites, and reduce the dechlorination efficiency.

[0037] The dechlorination agent prepared in the embodiment of the present application has a high specific surface area of 238.64 m 2 / g, which provides a large active surface and can load more mercapto (-SH) functional groups, so that even if the mass transfer is limited in a high-viscosity medium, there are still enough active sites to contact the chlorinated compounds; the average pore volume is 0.32 cm 3 / g, and the BET results show that the material has a large amount of mesoporous structure (2-50 nm) and macroporous structure (>50 nm) which can accommodate large organic chlorine pollutants (such as pesticides, PCB fragments) in the oil and fat, so that they can diffuse into the pore channel and contact the internal mercapto active sites. Microporous (<2 nm) materials can exclude these macromolecules. Although the oil viscosity is high, the large mesoporous channel can reduce the resistance of macromolecules to diffuse in the pore channel compared with microporous, and is not easily completely blocked by macromolecular impurities in the oil and fat, maintaining a certain permeability.

[0038] Mercapto (-SH) has strong affinity and specificity to various forms of chlorine, especially the chlorine atom in organic chlorinated compounds, which has very strong affinity. The main mechanism of action is nucleophilic substitution reaction (SN2) or formation of strong coordination bond. The sulfur atom in mercapto acts as a nucleophile to attack the electropositive carbon atom in organic chlorinated compounds (R-Cl) to replace the chlorine atom and form a stable sulfide bond (R-S-R'). For inorganic chlorine, mercapto can also remove it by coordination or ion exchange; the reaction of mercapto with chlorine does not depend on water medium and can still be effectively carried out in the hydrophobic environment of oil and fat, overcoming the problem of water treatment dechlorination agent in oil; compared with the main components such as triglyceride and fatty acid in oil and fat, the reactivity or affinity of mercapto to chlorinated compounds (especially C-Cl bond) is usually higher, providing a certain selectivity and reducing the competition interference of coexisting components.

[0039] The mercapto-modified Fe3O4@SiO2 dechlorination agent effectively overcomes the special difficulties of high viscosity of oil and fat medium, complex chlorine forms (especially organic chlorine), and many coexisting interferents, through its unique high specific surface area mesoporous structure, strong and oil-phase suitable mercapto functional groups, and key magnetic separation capacity.

[0040] In order to more clearly and specifically introduce the dechlorination agent, the preparation method thereof and the application thereof in oil dechlorination provided by the embodiments of the present application, the following will be described in combination with specific embodiments.

[0041] Example 1 Step 1: 10 ml of polyethylene glycol was dissolved in 100 ml of deionized water to form a mixed solution, 0.1 mol of ferric chloride and 0.05 mol of ferrous chloride were added to the above solution to form a solution A; 50 ml of ammonia water was added to 50 ml of polyethylene glycol and stirred uniformly, and nitrogen was introduced for 10 min to remove oxygen to form a mixed solution B; under the condition of ultrasonic, the solution A was added dropwise to the solution B, after the dropwise addition was completed, it was heated to 70℃ and reacted for 2 h, and nitrogen was introduced during the reaction process and accompanied by ultrasonic. After the reaction was completed, magnetic separation was performed, and anhydrous ethanol and water were repeatedly washed, and then vacuum drying was performed to obtain magnetic Fe3O4 particles for standby.

[0042] Step 2: 5 g of magnetic Fe3O4 particles was weighed and added to 150 ml of deionized water and ultrasonically dispersed for 30 min to form a dispersion liquid C; 10 ml of tetraethyl orthosilicate was dissolved in 500 ml of anhydrous ethanol to form a mixed liquid D; the dispersion liquid and the mixed liquid D were mixed together and ultrasonically stirred, 18 ml of ammonia water was added, and ultrasonic stirring was continued at 35℃ for 5 h, then magnetic separation was performed, and anhydrous ethanol and water were repeatedly washed until neutral, and then vacuum drying was performed to obtain a Fe3O4@ SiO2 carrier for standby.

[0043] Step 3: 1 g of the carrier prepared in step 2 was weighed and dispersed in 2 g of deionized water, and then added to 80 ml of a mixed solution of methanol and glycerol, and nitrogen was introduced to replace oxygen, and ultrasonic dispersion was performed for 30 min. 2 ml of ammonia water was added, and then 0.5 g of 3-mercaptopropyltrimethoxysilane was added, after the addition was completed, the reaction system was filled with nitrogen to be airtight, and heated to 80℃ and reacted for 6 h, after the reaction was completed, the reaction system was repeatedly washed with methanol and water until neutral, and then vacuum drying was performed to obtain an adsorbent Fe3O4@ SiO2-SH.

[0044] The ultrasonic power used in each of the above steps was 450 W.

[0045] Example 2 Step 1: 10 ml polyethylene glycol is dissolved in 100 ml deionized water to form a mixed solution, 0.1 mol of ferric chloride and 0.05 mol of ferrous chloride are added to the above solution, completely dissolved to form solution A; 50 ml of ammonia water is added to 50 ml of polyethylene glycol and stirred uniformly, and nitrogen is introduced for 10 min to remove oxygen to form a mixed solution B; under the environment of ultrasonic, solution A is added dropwise to solution B, after the dropwise addition is completed, it is heated to 70°C and reacted for 2 h, and nitrogen is introduced throughout the reaction process and accompanied by ultrasonic. After the reaction is completed, magnetic separation is performed, anhydrous ethanol and water are repeatedly washed, and vacuum drying is performed to obtain magnetic magnetite particles for standby.

[0046] Step 2: Step 2:

[0047] Step 3: Step 3:

[0048] The ultrasonic power used in each of the above steps is 450 W.

[0049] Example 3 Step 1: 10 ml polyethylene glycol is dissolved in 100 ml deionized water to form a mixed solution, 0.1 mol of ferric chloride and 0.05 mol of ferrous chloride are added to the above solution, completely dissolved to form solution A; 50 ml of ammonia water is added to 50 ml of polyethylene glycol and stirred uniformly, and nitrogen is introduced for 10 min to remove oxygen to form a mixed solution B; under the environment of ultrasonic, solution A is added dropwise to solution B, after the dropwise addition is completed, it is heated to 70°C and reacted for 2 h, and nitrogen is introduced throughout the reaction process and accompanied by ultrasonic. After the reaction is completed, magnetic separation is performed, anhydrous ethanol and water are repeatedly washed, and vacuum drying is performed to obtain magnetic magnetite particles for standby.

[0050] Step 2: Take 5g of magnetic magnetite particles and add to 150ml of deionized water, ultrasonic for 30min, form dispersion liquid C; 10ml of tetraethyl orthosilicate is dissolved in 1500ml of anhydrous ethanol to form mixed liquid D; the dispersion liquid and mixed liquid D are mixed together and ultrasonic stirring, 18ml of ammonia water is added, at 35°C, continue ultrasonic stirring for 5h, magnetic separation, anhydrous ethanol and water are repeatedly washed to neutral, vacuum drying to obtain Fe3O4@ SiO2 carrier, ready for use.

[0051] Step 3: Take 1g of the carrier prepared in step 2 and disperse it in 2g of deionized water, add 80ml of a mixed solution of methanol and glycerol, replace oxygen with nitrogen, ultrasonic dispersion for 30min. Add 2ml of ammonia water, add 0.5g of 3-mercaptopropyl trimethoxysilane, after the addition is complete, the reaction system is filled with nitrogen to seal, heated to 80°C and reacted for 6h, after the reaction is completed, repeatedly washed with methanol and water to neutral, vacuum drying to obtain the adsorbent Fe3O4@ SiO2-SH.

[0052] The ultrasonic power used in each of the above steps is 450W.

[0053] Example 4 Step 1: 10ml of polyethylene glycol is dissolved in 100ml of deionized water to form a mixed solution, 0.1mol of ferric chloride and 0.05mol of ferrous chloride are added to the above solution, completely dissolved to form solution A; 50ml of ammonia water is added to 50ml of polyethylene glycol and stirred evenly, and nitrogen is introduced for 10min to remove oxygen, forming a mixed solution B; under ultrasonic environment, solution A is added dropwise to solution B, after the addition is completed, heated to 70°C and reacted for 2h, nitrogen is introduced during the reaction process and accompanied by ultrasonic. After the reaction is completed, magnetic separation, anhydrous ethanol and water are repeatedly washed, vacuum drying to obtain magnetic magnetite particles for standby.

[0054] Step 2: Take 5g of magnetic magnetite particles and add to 150ml of deionized water, ultrasonic for 30min, form dispersion liquid C; 10ml of tetraethyl orthosilicate is dissolved in 500ml of anhydrous ethanol to form mixed liquid D; the dispersion liquid and mixed liquid D are mixed together and ultrasonic stirring, 18ml of ammonia water is added, at 35°C, continue ultrasonic stirring for 5h, magnetic separation, anhydrous ethanol and water are repeatedly washed to neutral, vacuum drying to obtain Fe3O4@ SiO2 carrier, ready for use.

[0055] Step 3: The carrier 1 g prepared in step 2 was weighed and dispersed into 2 g of deionized water, and then added into a mixed solution of 80 ml of methanol and 80 ml of glycerol. Oxygen was replaced by nitrogen, and ultrasonic dispersion was performed for 30 min. 2 ml of ammonia water was added, and then 0.5 g of 3-mercaptopropyltrimethoxysilane was added. After the addition was completed, the reaction system was sealed by filling with nitrogen, heated to 80℃, and reacted for 6 h. After the reaction was completed, the reaction system was repeatedly washed with methanol and water until neutral, and then vacuum dried to obtain the adsorbent Fe3O4@SiO2-SH.

[0056] The ultrasonic power used in each of the above steps was 600 W.

[0057] Comparative Example 1 Step 1: 10 ml of polyethylene glycol was dissolved in 100 ml of deionized water to form a mixed solution, 0.1 mol of ferric chloride and 0.05 mol of ferrous chloride were added to the above solution, and completely dissolved to form solution A; 50 ml of ammonia water was added to 50 ml of polyethylene glycol and stirred uniformly, and oxygen was removed by nitrogen for 10 min to form a mixed solution B; under the environment of ultrasonic, solution A was added dropwise to solution B, after the dropwise addition was completed, heating to 70℃ was performed for 2 h, and nitrogen was continuously introduced during the reaction process. After the reaction was completed, magnetic separation was performed, and the product was repeatedly washed with anhydrous ethanol and water, and then vacuum dried to obtain magnetic magnetite particles for standby.

[0058] Step 2: Step 2:

[0059] Comparative Example 2 Step 1: 10 ml of polyethylene glycol was dissolved in 100 ml of deionized water to form a mixed solution, 0.1 mol of ferric chloride and 0.05 mol of ferrous chloride were added to the above solution, and completely dissolved to form solution A; 50 ml of ammonia water was added to 50 ml of polyethylene glycol and stirred uniformly, and oxygen was removed by nitrogen for 10 min to form a mixed solution B; under the environment of ultrasonic, solution A was added dropwise to solution B, after the dropwise addition was completed, heating to 70℃ was performed for 2 h, and nitrogen was continuously introduced during the reaction process. After the reaction was completed, magnetic separation was performed, and the product was repeatedly washed with anhydrous ethanol and water, and then vacuum dried to obtain magnetic magnetite particles for standby.

[0060] Step 2: Take 5g of magnetic magnetite particles and add to 150ml of deionized water, ultrasonic for 30min, form dispersion liquid C; 10ml of tetraethyl orthosilicate is dissolved in 500ml of anhydrous ethanol to form mixed liquid D; the dispersion liquid and mixed liquid D are mixed together and ultrasonic stirring, 18ml of ammonia water is added dropwise, the ultrasonic is stopped, and stirring is continued at 35°C for 5h, magnetic separation, anhydrous ethanol and water are repeatedly washed to neutral, and vacuum drying is carried out to obtain Fe3O4@ SiO2 carrier, which is ready for use.

[0061] Step 3: Take 1g of the carrier prepared in step 2 and disperse it in 2g of deionized water, add 80ml of a mixed solution of methanol and glycerol, replace oxygen with nitrogen, ultrasonic for 30min. Add 2ml of ammonia water, and then add 0.5g of 3-mercaptopropyltrimethoxysilane. After the addition is completed, the reaction system is sealed by filling with nitrogen, heated to 80°C and reacted for 6h. After the reaction is completed, the product is repeatedly washed with methanol and water until it is neutral, and vacuum dried to obtain the adsorbent Fe3O4@ SiO2-SH.

[0062] The ultrasonic power used in each of the above steps is 450W.

[0063] Comparative Example 3 Step 1: 10ml of polyethylene glycol is dissolved in 100ml of deionized water to form a mixed solution, 0.1mol of ferric chloride and 0.05mol of ferrous chloride are added to the above solution, and the solution is completely dissolved to form solution A; 50ml of ammonia water is added to 50ml of polyethylene glycol and stirred uniformly, and nitrogen is introduced for 10min to remove oxygen to form mixed solution B; under ultrasonic environment, solution B is added dropwise to solution A, and after the addition is completed, it is heated to 70°C and reacted for 2h. Nitrogen is introduced during the reaction process and ultrasonic is accompanied. After the reaction is completed, magnetic separation is carried out, anhydrous ethanol and water are repeatedly washed, and vacuum drying is carried out to obtain magnetic magnetite particles ready for use.

[0064] Step 2: Take 5g of magnetic magnetite particles and add to 150ml of deionized water, ultrasonic for 30min, form dispersion liquid C; 10ml of tetraethyl orthosilicate is dissolved in 500ml of anhydrous ethanol to form mixed liquid D; the dispersion liquid and mixed liquid D are mixed together and ultrasonic stirring, 18ml of ammonia water is added dropwise, the ultrasonic is stopped, and stirring is continued at 35°C for 5h, magnetic separation, anhydrous ethanol and water are repeatedly washed to neutral, and vacuum drying is carried out to obtain Fe3O4@ SiO2 carrier, which is ready for use.

[0065] Step 3: Fe3O4@ SiO2-SH adsorbent was prepared by the following steps: 1 g of the carrier prepared in step 2 was dispersed in 2 g of deionized water, 80 ml of a mixed solution of methanol and glycerol was added, oxygen was replaced by nitrogen, and ultrasonic dispersion was performed for 30 min. 2 ml of ammonia water was added, 0.5 g of 3-mercaptopropyl trimethoxysilane was added, after the addition was completed, the reaction system was sealed by filling nitrogen, heated to 80°C and reacted for 6 h. After the reaction was completed, methanol and water were repeatedly washed until neutral, and vacuum drying was performed to obtain the adsorbent Fe3O4@ SiO2-SH.

[0066] The ultrasonic power used in the above steps was 450 W.

[0067] Comparative Example 4 Step 1: 10 ml of polyethylene glycol was dissolved in 100 ml of deionized water to form a mixed solution, 0.1 mol of ferric chloride and 0.05 mol of ferrous chloride were added to the above solution, and the solution was completely dissolved to form solution A; 50 ml of ammonia water was added to 50 ml of polyethylene glycol and stirred uniformly, and oxygen was removed by nitrogen for 10 min to form a mixed solution B; under the environment of ultrasonic, solution A was added dropwise to solution B, after the addition was completed, it was heated to 70°C and reacted for 2 h, and nitrogen was continuously introduced during the reaction process and accompanied by ultrasonic. After the reaction was completed, magnetic separation was performed, and anhydrous ethanol and water were repeatedly washed, and vacuum drying was performed to obtain magnetic magnetite particles for standby.

[0068] Step 2: Step 2:

[0069] Step 3: Fe3O4@ SiO2-SH adsorbent was prepared by the following steps: 1 g of the carrier prepared in step 2 was dispersed in 2 g of deionized water, 80 ml of a mixed solution of methanol and glycerol was added, oxygen was replaced by nitrogen, and ultrasonic dispersion was performed for 30 min. 2 ml of ammonia water was added, 0.5 g of 3-mercaptopropyl trimethoxysilane was added, after the addition was completed, the reaction system was sealed by filling nitrogen, heated to 80°C and reacted for 6 h. After the reaction was completed, methanol and water were repeatedly washed until neutral, and vacuum drying was performed to obtain the adsorbent Fe3O4@ SiO2-SH.

[0070] The ultrasonic power used in the above steps was 450 W.

[0071] Performance test Table 1 Raw materials and process conditions of some examples and comparative examples

[0072] The particle size and mercapto content of the dechlorination agent prepared in the examples and comparative examples were measured. The particle size of the dechlorination agent was measured by a laser particle size distribution instrument (wet method) for particle size testing, and the median particle size (D50) data was used uniformly.

[0073] The method for measuring mercapto was determined by ELLMAN reagent method: 5,5'-dithiobis(2-nitrobenzoic acid) is Ellman reagent, which has a characteristic absorption at 325 nm. After the surface mercapto of the adsorbent reacts, 2-nitro-5-thiobenzoic acid (TNB) is displaced. Under slightly alkaline conditions, TNB has a strong absorption peak at 412 nm, and its concentration and absorbance value comply with the Lambert-Beer law. The reaction of DTNB with mercapto is quantitative, and the content of mercapto in the sample is determined by ultraviolet-visible spectrophotometry. The measurement results are shown in Table 2.

[0074] Table 2 Particle size and mercapto content results

[0075] As can be seen from Table 2, the particle size of Example 1 and Comparative Example 2 is small mainly because: the high-intensity shear force generated by ultrasonic cavitation in Example 1 effectively disperses the magnetic agglomerates of Fe3O4 nanoparticles, obtaining magnetic cores with smaller size and uniform dispersion; in addition, ultrasonic waves can prevent particles from adhering to each other and secondary aggregation during the growth of the SiO2 shell, ensuring the formation of a thin and uniform coating layer. The particle size of Example 1 and Comparative Example 3 is large mainly because under low silicon source concentration, the number of active silicon acid monomers generated by hydrolysis in the solution is small, resulting in sparse SiO2 nucleation sites on the surface of the Fe3O4 magnetic core and slow growth rate, and the limited supply of silicon source reduces the tendency of secondary aggregation between particles through silicon hydroxyl condensation, while avoiding the rapid accumulation of excess silicon source on a single magnetic core to form a thick shell. The particle size of Example 1 and Example 2 is slightly larger mainly because in the grafting process, mercapto not only reacts with surface silicon hydroxyl groups, but also undergoes hydrolysis and condensation, resulting in the extension and growth of an additional silicon-oxygen network on the particle surface, which increases the thickness of the coating layer. In addition, the high-density mercapto molecular chain forms a steric hindrance layer on the particle surface, increasing the effective physical size of the particle. At the same time, the dense organic layer also makes the particle size measurement show a larger hydrodynamic diameter.

[0076] The prepared dechlorination agent was evaluated for performance, and the specific operation was as follows: the dechlorination agent was mixed with oil and fat (according to a mass ratio of 1:100), and was ultrasonically adsorbed at 80°C for 30 min to obtain adsorbed oil and fat. The adsorbent was recovered by magnetic separation, and the specific removal results are shown in Table 3.

[0077] Table 3 Performance test results

[0078] From Table 3, it can be seen that the adsorbent prepared in Example 1 has the best effect on removing organic chlorine. Although the content of sulfhydryl group in Comparative Example 3 is higher than that in Example 1, the effect of removing organic chlorine is slightly worse, which may be caused by the residue of the adsorbent (the core reason for the small particle residue is that the weak magnetic response force cannot overcome the huge resistance of the high viscosity grease and the interference of Brownian motion).

[0079] Table 4 Raw materials, process conditions and performance test results of examples and comparative examples

[0080] From Examples 1 and 4 and Comparative Example 2, it can be seen that with the increase of ultrasonic power, the particle size of the adsorbent gradually decreases, which may be caused by the aggregation of magnetic cores due to insufficient ultrasonic power, resulting in uneven SiO2 coating. From Examples 1 and 3 and Comparative Examples 3 and 4, it can be seen that with the decrease of the concentration of silicon source, the particle size of the adsorbent also gradually decreases, which may be caused by the small concentration of silicon source, resulting in less silicic acid monomer generated by hydrolysis, which limits the thickness of the SiO2 shell layer, so that the overall particle size of the chlorine removal agent decreases. From the table, it can be seen that the chlorine removal agent prepared in Example 1 has the best effect on removing chlorine from waste animal and vegetable oils. When the particle size is small, the surface energy of the particle is high, and there is a lack of sufficient steric hindrance or electrostatic repulsion in the oil, so the particle is easy to form irreversible agglomeration and form "secondary agglomerates". A large number of sulfhydryl groups will be wrapped inside the agglomerates, resulting in a decrease in the actual effective specific surface area and a significant decrease in the utilization rate of active sites. When the particle size is too small, it is difficult to separate the particles by magnetic separation, resulting in secondary pollution. When the particle size is too large, the total specific surface area of the particles will decrease significantly, which means that more sulfhydryl groups cannot be exposed to the oil, and the number of sulfhydryl groups available for contact and reaction with chlorinated organic compounds decreases, resulting in a decrease in activity.

[0081] From Figure 1 , 2 and Table 5, it can be seen that the Fe3O4@SiO2 carrier is prepared first, and then modified to make the sulfhydryl groups uniformly distributed on the inner wall of the pores to form a "nanoreactor", and the -SH in the pores can accurately capture the chlorinated compounds. From the BET, it can be seen that the apparent volume of the chlorine removal agent prepared in Example 1 decreases from 0.38 cm 3 / g to 0.32 cm 3 / g, and the specific surface area decreases from 251.04 m 2 / g to 238.64 m 2 / g, which is caused by the fact that the mesoporous inner wall is covered with a large number of -SH, so that the chlorinated fatty acid esters and other chlorinated macromolecules that diffuse into the pores can be effectively removed, avoiding the risk that the chlorinated macromolecules that enter the chlorine removal agent cannot be effectively removed.

[0082] Table 5 Specific surface area and average pore volume of Fe3O4@SiO2 support and dechlorination agent prepared in Example 1 and Comparative Example 2

[0083] From Figure 2 , 3 and Table 1, the specific surface area of the dechlorination agent prepared in Example 1 (238.64 m 2 / g) was about 39% higher than that of the dechlorination agent prepared in Comparative Example 2 (171.78 m 2 / g); the specific surface area directly determines the number of adsorption sites. A larger specific surface area means more active sites can contact and capture chlorinated compounds (such as chlorinated fatty acid esters, etc.) in oil and fat, significantly increasing the maximum adsorption capacity per unit mass of dechlorination agent. The pore volume of the dechlorination agent prepared in Example 1 (0.32 cm 3 / g) was 28% higher than that of the dechlorination agent prepared in Comparative Example 2 (0.25 cm 3 / g). Chlorinated organic compounds (such as chlorinated fatty acid esters, etc.) in oil and fat have a larger molecular size. A larger pore volume provides sufficient space to accommodate these molecules, avoiding pore blockage, and the high viscosity of oil and fat helps chlorinated compounds quickly diffuse to the adsorption sites, shortening the adsorption equilibrium time and improving the adsorption effect.

[0084] From Figure 4 , 5 , and 6, the particle size of the dechlorination agent prepared in Example 1 was smaller than that of the dechlorination agent prepared in Comparative Example 2, and the dechlorination agent prepared in Comparative Example 2 had agglomeration, which may be because the ultrasound produced strong mechanical shear force, which could break the initial aggregates formed between the magnetic core particles due to van der Waals force and magnetic attraction, and disperse them into smaller monodisperse particles; at the same time, the local turbulence and microjet flow generated by the ultrasound can maintain the uniform distribution of the particles in the solution, avoiding the re-aggregation of the dispersed particles; the particle size of the dechlorination agent prepared in Example 1 was smaller than that of the dechlorination agent prepared in Comparative Example 5, which may be due to the rapid hydrolysis and condensation of a large amount of silicic acid monomers under high silicon source concentration, and the monomers are easy to form free SiO2 particles, and the ultrasound is difficult to prevent the collision and agglomeration of these particles with the magnetic core or each other; at the same time, the SiO2 shell grows faster and more unevenly under high concentration, and the locally thick shell is easy to stick together through van der Waals force, and the shear force of the ultrasound is not enough to break the close agglomeration caused by the excessive growth of the shell, resulting in an increase in particle size.

Claims

1. A method for producing a chlorine scavenger, characterized by, The method comprises the following steps: Step 1: dissolving ferric chloride and ferrous chloride in a polyethylene glycol solution to form a solution A; adding ammonia water into the polyethylene glycol, stirring until uniform and removing oxygen to form a mixed solution B; under the condition of ultrasonic, adding the solution A into the mixed solution B drop by drop, after the dropwise addition, reacting at 50-80 DEG C, and in the process of reaction, protecting by nitrogen and keeping ultrasonic, after the reaction, separating, washing and drying to obtain magnetic Fe3O4 particles; Step 2: taking the magnetic Fe3O4 particles and adding into deionized water to form a dispersion C; dissolving tetraethyl orthosilicate in anhydrous ethanol to form a mixed liquid D; mixing the dispersion C and the mixed liquid D and stirring under ultrasonic, then adding ammonia water drop by drop, continuing to stir under ultrasonic at 30-50 DEG C, after the reaction, separating, washing and drying to obtain a Fe3O4@SiO2 carrier; Step 3: taking the Fe3O4@SiO2 carrier and dispersing into deionized water, adding a mixed solution of methanol and glycerol, removing oxygen and dispersing under ultrasonic, then adding ammonia water, further adding a mercapto silane coupling agent, after the addition, sealing the reaction system by filling with inert gas, heating to 50-90 DEG C to react, after the reaction, washing and drying to obtain the adsorbent Fe3O4@SiO2-SH, namely the chlorine removing agent.

2. The method of claim 1, wherein the dechlorinating agent is prepared by the steps of: The volume ratio of the tetraethyl orthosilicate to the anhydrous ethanol in the mixed liquid D is 1:50-200.

3. The method of claim 1, wherein the dechlorinating agent is prepared by the steps of: The power of the ultrasonic is 450-600 W.

4. The method of claim 1, wherein the dechlorinating agent is prepared by the steps of: The molar ratio of Fe in solution A 2+ and Fe 3+ was 1 :

2.

5. The method of claim 1, wherein the dechlorinating agent is prepared by the steps of: In step 2, the molar ratio of Fe in the magnetic Fe3O4 particles to Si in the tetraethyl orthosilicate is 5-20:1-5.

6. The method of claim 1, wherein the dechlorinating agent is prepared by the steps of: In step 3, the weight ratio of the amount of the mercapto silane coupling agent to the Fe3O4@SiO2 carrier is 0.1-1:

1.

7. The method of claim 1, wherein the dechlorinating agent is prepared by the steps of: The mercapto silane coupling agent is 3-mercaptopropyl trimethoxysilane.

8. The method of claim 1, wherein the dechlorinating agent is prepared by the steps of: The reaction temperature in step 1 is 50-80 DEG C, and the reaction time is 1-3 h; the reaction temperature in step 2 is 30-50 DEG C, and the reaction time is 2-8 h; the reaction temperature in step 3 is 50-90 DEG C, and the reaction time is 2-10 h.

9. The chlorine removing agent prepared by the preparation method of the chlorine removing agent according to any one of claims 1-8.

10. The application of the chlorine removing agent according to claim 9 in oil and fat dechlorination.

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