Chitosan-based waste lubricating oil deironing reagent as well as preparation method and application thereof

Abstract

The invention relates to the field of hazardous waste treatment, in particular to a chitosan-based waste lubricating oil deironing reagent and a preparation method and application thereof. The preparation method of the iron removal reagent comprises the following steps: S1, mixing chitosan and an activating agent to obtain a mixture; the content of the activating agent in the mixture does not exceed 20wt%; s2, roasting the mixture, and then cooling to obtain a reactant; the heating rate of roasting is 2-8 DEG C / min, the temperature is raised to 500-900 DEG C, and the heat preservation time of roasting is 3-6 hours; and S3, grinding and screening the reactant to obtain the iron removal reagent. The prepared iron removal reagent can be used for removing colloidal iron in waste lubricating oil, the iron removal rate of the iron removal reagent reaches up to 95% or above, the used iron removal reagent can be reused after acid pickling and secondary baking, the production cost is reduced, and the iron removal reagent has good industrial application potential.

Description

Technical Field

[0001] The present invention relates to the technical field of hazardous waste treatment, and more specifically, to a chitosan-based iron-removing reagent for waste lubricating oil, its preparation method and application. Background Art

[0002] Lubricating oil can play roles such as lubricating and reducing friction, assisting in cooling and temperature reduction, sealing and preventing leakage, rust prevention and corrosion protection, shock absorption and buffering for mechanical components such as engines. During the use of lubricating oil, impurities such as metallic iron and partially oxidized oxygen-containing organic substances in the lubricating oil are introduced due to mechanical wear and high-temperature oxidation. Waste lubricating oil belongs to hazardous waste and cannot be directly discarded, otherwise it will not only pollute the environment but also cause waste of resources. China is short of petroleum resources, and it is of great significance to recover the base oil from waste lubricating oil. At present, waste lubricating oil is generally recovered for base oil by distillation. However, the iron metal impurities contained in waste lubricating oil will clog the distillation equipment, reduce the distillation efficiency and deteriorate the fraction quality. Since lubricating oil additives and high-temperature oxidation products of lubricating oil contain functional groups such as O and N, they are prone to complex with iron elements, so that iron is dispersed in waste lubricating oil in the form of colloid and is difficult to be separated by mechanical methods. Therefore, there is an urgent need to develop an efficient and low-cost iron-removing reagent to reduce the iron content in waste lubricating oil, so that waste lubricating oil can be effectively pretreated and provide suitable raw materials for subsequent distillation.

[0003] At present, some patented technologies involve the treatment of iron elements in waste lubricating oil. For example, patents CN201621350643.X and CN201821319193.7 respectively report a device for removing iron filings from waste lubricating oil, but they are all mechanical methods and cannot achieve deep removal of trace iron. Patent CN 113117685B discloses a SiO2-TiO2-ZnO containing active component Ni, which can remove trace iron in waste lubricating oil, but the inorganic compounds therein are prone to disperse in waste lubricating oil and are liable to cause secondary pollution. Summary of the Invention

[0004] In order to solve the problems existing in the above background art, the present invention provides a new reagent for removing iron from waste lubricating oil, which is a purification reagent for waste lubricating oil using chitosan as a raw material.

[0005] In order to achieve the above object, the present invention is realized by the following technical solutions:

[0006] In the first aspect of the present invention, there is provided a chitosan-based iron-removing reagent for waste lubricating oil, which is obtained by calcination. Chitosan-based polymers and their carbonized materials are rich in nitrogen- and oxygen-containing functional groups such as amino, hydroxyl, aldehyde and carboxyl groups, and can effectively complex with iron elements in lubricating oil, thereby achieving its deep removal. Moreover, the polymers and carbon-nitrogen materials are structurally stable in lubricating oil and there is no secondary pollution, and are expected to become promising iron-removing reagents for waste lubricating oil.

[0007] The iron-removing reagent provided by the present invention carbonizes chitosan at 500-900°C under isolation control, crushes and sieves it into appropriate particle sizes, adds it to waste lubricating oil containing iron elements and mixes well, and the lubricating oil and the iron-removing reagent can be separated by centrifugation or filtration, thereby obtaining purified lubricating oil.

[0008] Further, the cellulose is derived from aquatic waste such as crab shells and shrimp shells;

[0009] Further, the carbonization process can be further activated by sodium carbonate, zinc chloride or potassium hydroxide.

[0010] In the second aspect of the present invention, a preparation method of the above-mentioned chitosan-based waste lubricating oil iron-removing reagent is provided, including the following steps:

[0011] S1. Take chitosan and an activator and mix them to obtain a mixture; the content of the activator in the mixture does not exceed 20 wt%.

[0012] S2. Roast the mixture and then cool it to obtain a reactant; the heating rate of the roasting is 2-8°C / min, and it is heated to 500-900°C (for example: 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, etc.), and the holding time of the roasting is 3-6 h;

[0013] S3. Grind and sieve the reactant to obtain an iron-removing reagent.

[0014] Under the preferred scheme, the chitosan raw material is derived from one or more of crab shells and shrimp shells.

[0015] Under the preferred scheme, the activator in step S1 is one or more of sodium carbonate, zinc chloride and potassium hydroxide.

[0016] Under the preferred scheme, the content of the activator in the mixture in step S1 is 10 wt% - 17 wt%.

[0017] Under the preferred scheme, the roasting in step S2 is carried out in an air-free or inert gas atmosphere, and the inert gas is nitrogen and / or argon.

[0018] Under the preferred scheme, the roasting in step S2 is carried out in a muffle furnace or a tube furnace.

[0019] Under the preferred scheme, the particle size of the iron-removing reagent in step S3 is 20-100 mesh; more preferably, the particle size of the iron-removing reagent is 60-80 mesh (for example: 60 mesh, 63 mesh, 65 mesh, 68 mesh, 70 mesh, 73 mesh, 75 mesh, 78 mesh, 80 mesh, etc.).

[0020] The third aspect of the present invention provides an application of the above-mentioned chitosan-based waste lubricating oil iron removal reagent for adsorbing colloidal iron in waste lubricating oil.

[0021] In the present invention, using chitosan as the raw material, it is fully mixed with an appropriate amount of activator (5-20 wt%, preferably 10-15 wt%); pyrolyzed in a muffle furnace or a tube furnace under an air-free or nitrogen / argon atmosphere, with the temperature controlled at 500-900 °C for sufficient carbonization; the carbonized product is crushed and screened into a suitable particle size range of 20-100 mesh (preferably 60-80 mesh) to obtain the iron removal reagent; an appropriate amount of the iron removal reagent is fully and evenly mixed with the iron-containing waste lubricating oil for a certain time, and then separated by centrifugation or filtration to obtain the purified waste lubricating oil.

[0022] Further, the iron removal reagent is placed in the waste lubricating oil, oscillated on a shaker at a rate of 300-900 rpm for 1.5-2.5 h, and then centrifuged at 5000-10000 rpm for 5-30 min to obtain the purified lubricating oil. The mass-volume ratio (g / mL) of the iron removal reagent to the waste lubricating oil is 0.1:(8-10).

[0023] Further, the iron removal reagent after adsorbing colloidal iron in the waste lubricating oil is washed with an acidic solution and then subjected to secondary baking, and is used again to adsorb colloidal iron in the waste lubricating oil; the heating rate of the secondary baking is 2-4 °C / min, and it is heated to 200-400 °C, and the holding time of the baking is 1-2 h.

[0024] Under the preferred scheme, the chitosan raw material is derived from aquatic product wastes such as crab shells and shrimp shells.

[0025] Under the preferred scheme, the activator is sodium carbonate or zinc chloride, etc.

[0026] The beneficial effects of the present invention:

[0027] The chitosan raw material used in the present invention has a wide source and low price, and no impurities are introduced during the process of treating waste lubricating oil. After the treatment, the iron removal reagent can be regenerated and reused by pickling and secondary baking; the iron element content in the waste lubricating oil can be reduced to the ppm level, meeting the requirements of subsequent rectification.

[0028] The present invention uses chitosan-based carbon materials as waste lubricating oil iron removal reagents, and its iron removal efficiency can reach more than 95%, and the iron element can be reduced to the ppm level. This method uses chitosan derived from agricultural and forestry waste as the raw material, which not only reduces the production cost, but also turns waste into treasure, providing a good solution for the effective utilization of waste lubricating oil and having industrial application potential.

[0029] The raw material chitosan used in the present invention is rich in nitrogen- and oxygen-containing functional groups such as amino and hydroxyl groups, and will be partially converted into oxygen-containing functional groups such as aldehyde and carboxyl groups during the carbonization process. The rich nitrogen- and oxygen-containing functional groups can be used as chelating ligands to bind with iron elements in waste lubricating oil. The activation process can create pores in the reagent and increase the specific surface area, thereby improving the iron removal efficiency. The iron removal reagent is essentially activated carbon with a stable structure and will not dissolve in the lubricating oil to cause secondary pollution. Therefore, the iron removal reagent prepared from chitosan as the raw material has the advantages of high efficiency, low consumption and renewability. Description of the Drawings

[0030] Figure 1 is the SEM image of the iron removal reagent prepared in Example 1 of the present invention;

[0031] Figure 2 is the infrared spectrum of the iron removal reagent prepared in Example 1 of the present invention;

[0032] Figure 3 is the EDS mapping image after the iron removal reagent prepared in Example 1 of the present invention treats waste lubricating oil. Detailed Embodiments

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. The experimental methods in the embodiments are all conventional methods unless otherwise specified. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0035] Description of the sources of experimental materials:

[0036] The waste lubricating oil used in the following embodiments is taken from an auto repair company in Shihezi City, Xinjiang. Before the experiment, solid impurities including iron filings are removed by filtration, and the remaining iron content measured by spectrophotometry (GB 2365-1980) is 147.9 ppm.

[0037] Example 1

[0038] The preparation process of the chitosan-based waste lubricating oil iron removal reagent includes the following steps:

[0039] Mix 15.0 g of chitosan and 3 g of zinc chloride evenly in an agate mortar, put them into a 50 mL crucible and cover it, roast in a muffle furnace at 700 °C for 8 h, take it out after sufficient cooling, grind and sieve to 60 - 80 mesh to obtain the iron removal reagent.

[0040] Take 0.3 g of this reagent and place it in a 100 mL conical flask containing 25 mL of waste lubricating oil, and oscillate in a shaker for 2 h. The product is centrifuged to obtain purified lubricating oil. The remaining iron content is measured to be 0.9 ppm by spectrophotometry (GB 2365 - 1980), and the removal rate is 99.4%.

[0041] As Figure 1 shown is the SEM image of the iron removal reagent prepared in Example 1. It can be seen that the reagent has a porous and loose property, providing a diffusion channel for the adsorption of iron. As Figure 2 shown is the infrared spectrum of the iron removal reagent prepared in Example 1. From the position and intensity of the stretching vibration peaks, it can be seen that the reagent is rich in functional groups such as hydroxyl, carboxyl, and amino groups, providing adsorption sites for iron elements. As Figure 3 shown is the EDS mapping of the waste lubricating oil treated with the iron removal reagent prepared in Example 1. From the distribution of Fe, C, O, and N elements, it can be seen that a large amount of iron elements are adsorbed on the carbon, oxygen, and nitrogen substrate of the material.

[0042] Example 2

[0043] The preparation process of the chitosan-based iron removal reagent for waste lubricating oil includes the following steps:

[0044] Mix 10 g of chitosan and 2 g of sodium carbonate evenly in an agate mortar, put them into a 50 mL crucible and cover it, roast in a muffle furnace at 700 °C for 8 h, take it out after sufficient cooling, grind and sieve to 60 - 80 mesh to obtain the iron removal reagent.

[0045] Take 0.3 g of this reagent and place it in a 100 mL conical flask containing 25 mL of waste lubricating oil, and oscillate in a shaker for 2 h. The product is centrifuged to obtain purified lubricating oil. The remaining iron content is measured to be 1.1 ppm by spectrophotometry (GB 2365 - 1980), and the removal rate is 99.3%.

[0046] Example 3

[0047] The preparation process of the chitosan-based iron removal reagent for waste lubricating oil includes the following steps:

[0048] Mix 15.0 g of chitosan and 5 g of zinc chloride evenly in an agate mortar, put them into a 50 mL crucible and cover it, roast in a muffle furnace at 700 °C for 8 h, take it out after sufficient cooling, grind and sieve to 60 - 80 mesh to obtain the iron removal reagent.

[0049] Take 0.3 g of this reagent and place it in a 100 mL conical flask containing 25 mL of waste lubricating oil, and oscillate it in a shaker for 2 h. The product is centrifuged to obtain purified lubricating oil. The remaining iron content is measured to be 5.2 ppm by spectrophotometry (GB 2365-1980), and the removal rate is 96.5%.

[0050] Example 4

[0051] The preparation process of the chitosan-based waste lubricating oil iron removal reagent includes the following steps:

[0052] Mix 15.0 g of chitosan and 3 g of the activator potassium hydroxide evenly in an agate mortar, put them into a 50 mL crucible and cover it, roast it in a muffle furnace at 700 °C for 8 h, take it out after sufficient cooling, grind it and sieve it to 60-80 mesh to obtain the iron removal reagent.

[0053] Take 0.3 g of this reagent and place it in a 100 mL conical flask containing 25 mL of waste lubricating oil, and oscillate it in a shaker for 2 h. The product is centrifuged to obtain purified lubricating oil. The remaining iron content is measured to be 6.3 ppm by spectrophotometry (GB 2365-1980), and the removal rate is 95.7%.

[0054] Example 5

[0055] Renewability test of the chitosan-based waste lubricating oil iron removal reagent:

[0056] The solid adsorption reagent after centrifugation in Example 1 was washed thoroughly in 1 mol / L hydrochloric acid to remove iron elements, roasted in a muffle furnace at 300 °C for 1.5 h, and used again for waste lubricating oil treatment. The remaining iron content was measured to be 1.2 ppm, and the removal rate was 99.2%. Repeat the above steps. The remaining iron contents after 2-8 times of regeneration are 1.5 ppm, 2.2 ppm, 2.5 ppm, 2.7 ppm, 2.8 ppm, 2.9 ppm, and 3.0 ppm respectively, and the removal rates are 99.0%, 98.5%, 98.3%, 98.2%, 98.1%, 98.0%, and 98.0%. It fully shows that this reagent has good renewability.

[0057] Comparative Example 1

[0058] The preparation process of the chitosan-based waste lubricating oil iron removal reagent includes the following steps:

[0059] Put 15.0 g of chitosan into a 50 mL crucible and cover it, roast it in a muffle furnace at 700 °C for 8 h, take it out after sufficient cooling, grind it and sieve it to 60-80 mesh to obtain the iron removal reagent.

[0060] Take 0.3 g of this reagent and place it in a 100 mL conical flask containing 25 mL of waste lubricating oil, and oscillate it in a shaker for 2 h. The product is separated by centrifugation to obtain purified lubricating oil. The remaining iron content is measured to be 18.5 ppm by spectrophotometry (GB 2365-1980), and the removal rate is 87.5%.

[0061] Comparative Example 2

[0062] The purpose of this comparative example is for comparison, and the purpose is to clarify the necessity of the calcination operation. Directly take 0.3 g of chitosan raw material and place it in a 100 mL conical flask containing 25 mL of waste lubricating oil, and oscillate it in a shaker for 2 h. The product is separated by centrifugation to obtain purified lubricating oil. The measured remaining iron content is 32.4 ppm, and the removal rate is 79.1%. It shows that although chitosan has a certain effect on the removal of iron, after being calcined into a carbon material, the efficiency is greatly improved.

[0063] In summary, the present invention discloses a chitosan-based reagent for removing iron elements from waste lubricating oil, that is, a solid material is prepared from chitosan as a raw material, and it is used as a reagent to remove a small amount of iron elements that are difficult to mechanically separate in waste lubricating oil. Its specific application method is: chitosan extracted from aquatic waste such as crab shells and shrimp shells is carbonized at high temperature under air isolation conditions to obtain a reagent, which is added to waste lubricating oil at room temperature for mixing. After completion, the lubricating oil and the carbon material are separated to obtain lubricating oil with an iron element removal rate of more than 95%. The present invention uses chitosan for the purification of lubricating oil, which not only reduces the production cost, but also improves the quality of lubricating oil, and has good environmental and economic benefits.

[0064] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a chitosan-based waste lubricating oil iron removal reagent, characterized in that: The steps include: S1, mixing chitosan and an activator to obtain a mixture, wherein the content of the activator in the mixture does not exceed 20wt%; S2, calcining the mixture, and then cooling to obtain a reactant; the calcination temperature is increased at a rate of 2 to 8°C / min, the temperature is increased to 500 to 900°C, and the calcination temperature is kept for 3 to 6 hours; S3, grinding and screening the reactants to obtain an iron removal reagent.

2. The method for preparing the chitosan-based waste lubricating oil iron removal reagent according to claim 1, characterized in that: In step S1, the chitosan raw material is derived from one or more of crab shells and shrimp shells, and the activator is one or more of sodium carbonate, zinc chloride and potassium hydroxide.

3. The method for preparing the chitosan-based waste lubricating oil iron removal reagent according to claim 1, characterized in that: The content of the activator in the mixture in step S1 is 10wt% to 17wt%.

4. The method for preparing the chitosan-based waste lubricating oil iron removal reagent according to claim 1, characterized in that: The calcination in step S2 is carried out in an airtight state or in an inert gas atmosphere, wherein the inert gas is nitrogen and / or argon.

5. The method for preparing the chitosan-based waste lubricating oil iron removal reagent according to claim 1, characterized in that: The calcination in step S2 is carried out in a muffle furnace or a tube furnace.

6. The method for preparing the chitosan-based waste lubricating oil iron removal reagent according to claim 1, characterized in that: The particle size of the iron removal agent in step S3 is 60 to 80 meshes.

7. A chitosan-based waste lubricating oil iron removal reagent prepared by the preparation method according to claims 1 to 6.

8. An application of the chitosan-based waste lubricating oil iron removal reagent according to claim 7, characterized in that: Used to absorb colloidal iron in waste lubricating oil.

9. The use of the chitosan-based waste lubricating oil iron removal reagent according to claim 8, characterized in that: The iron removal reagent is placed in the waste lubricating oil and shaken at a rate of 300-900 rpm in a shaker for 1.5-2.5 hours, and then centrifuged at 5000-10000 rpm for 5-30 minutes to obtain the purified lubricating oil. The mass volume ratio (g / mL) of the iron removal reagent to the waste lubricating oil is 0.1:(8-10).

10. The use of the chitosan-based waste lubricating oil iron removal reagent according to claim 8, characterized in that: The iron removal reagent after adsorbing the colloidal iron in the waste lubricating oil is washed with an acidic solution, baked twice, and used again to adsorb the colloidal iron in the waste lubricating oil; the heating rate of the secondary baking is 5-10°C / min, the temperature is raised to 500-900°C, and the insulation time of the baking is 1-2h.

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