Preparation method and application of magnetic composite particles

Abstract

The invention discloses a preparation method and application of magnetic composite particles. The magnetic composite particles are prepared by pretreating silicate minerals, sequentially performing nanocrystallization treatment and lipophilic modification on a fibrous organic base material, and compounding the pretreated silicate, the modified organic base material and magnetic microspheres. According to the preparation method, the solubility and dispersity of the base material in water can be effectively improved through nanocrystallization of the organic base material, and the affinity with insoluble protein and lipid substances is improved through lipophilic modification of the organic base material; the base material is compounded with the magnetic particles, so that the magnetic recoverability is realized; the composite particles are used for recycling protein and lipid substances in aquatic product processing wastewater according to requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of aquatic product processing wastewater treatment, and specifically relates to a preparation method and application of magnetic composite particles. Background Art

[0002] The development of technology for recovering organic matter from aquatic product processing wastewater is not only conducive to reducing the discharge of high-concentration organic wastewater and alleviating the operating burden of sewage treatment plants, but more importantly, the efficient recovery of high-value organic matter in wastewater is also of great practical significance for promoting quality and efficiency improvements of aquatic product processing enterprises and creating considerable additional economic benefits.

[0003] Chinese invention patent CN201210340514.2 discloses a process for treating wastewater from aquatic product processing, which is as follows: wastewater - grid interception - solid suspended matter separation - oil removal device - pebbles and shells mixed adsorption - filtration - pH adjustment - flocculation precipitation - filtration - oxidation flocculation precipitation - secondary filtration of shell fragments - qualified water. The invention uses pebbles and shells in this process, which can be obtained locally and have sufficient raw materials. The shells are processed during the production process and reused, which reduces the cost by 15% compared with the traditional process. However, this process cannot effectively enrich and recycle high-value organic matter in wastewater from aquatic product processing, and the treatment efficiency is low. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for preparing magnetic composite particles and their application, which is specifically achieved through the following technical solutions: The first aspect of the present invention provides a method for preparing magnetic composite particles, the method comprising the following steps: 1) Add the silicate mineral to the NaOH solution, stir magnetically, centrifuge, remove the supernatant, transfer the precipitate to an equal volume of HCl solution, stir magnetically, centrifuge to remove the supernatant, collect the precipitate and freeze-dry it to obtain the pretreated silicate for standby use; 2) Disperse chitosan in NaOH / urea / deionized water, stir, freeze-thaw, stir and melt at room temperature, repeat freeze-thaw-stirring three times, add an equal volume of anhydrous ethanol to the final solution, stir magnetically, remove the supernatant by centrifugation, transfer the precipitate into a dialysis bag, dialyze with deionized water, remove the supernatant by centrifugation, freeze-dry the precipitate, and obtain chitosan nanowhiskers; 3) Disperse chitosan nanowhiskers in NaOH / urea / deionized water, stir, freeze-thaw, and stir and melt at room temperature, repeat three times, add pretreated silicate minerals, sodium tripolyphosphate, and Ci-ZnFe2O4 to the solution, stir, centrifuge to remove the supernatant, transfer the precipitate into a dialysis bag, dialyze with deionized water, and freeze-dry the precipitate to obtain magnetic particles before lipophilic modification; 4) Ultrasonic dispersion of the magnetic particles before lipophilic modification in methoxypolyethylene glycol silane, constant temperature cross-linking, centrifugation to remove the supernatant, precipitate freeze-drying, and obtain lipophilic modified magnetic composite particles.

[0005] Furthermore, in step 1), the molecular formula of the silicate mineral is Al2[Si2O5](OH)4•2H2O, and the material-liquid ratio of the silicate mineral to the NaOH solution is 1:8-12 (g:mL).

[0006] Furthermore, in step 2) and step 3), NaOH / urea / deionized water are prepared in a weight concentration ratio of 11:4:85, the freeze-thaw temperature is -80°C, and the freeze-thaw time each time is 4 hours.

[0007] Furthermore, in step 2), the mass ratio of chitosan to NaOH / urea / deionized water is 1:45-55.

[0008] Furthermore, in step 3), the mass ratio of chitosan nanowhiskers to NaOH / urea / deionized water is 1:45-55.

[0009] Furthermore, in step 3), 8-12 g of silicate mineral, 1-3 g of sodium tripolyphosphate, and 4-6 g of Ci-ZnFe2O4 are added to every 100 g of NaOH / urea / deionized water.

[0010] The second aspect of the present invention provides magnetic composite particles obtained by the above preparation method.

[0011] The third aspect of the present invention provides the use of magnetic composite particles in the treatment of aquatic product processing wastewater.

[0012] Specifically, the application of magnetic composite particles in enriching insoluble organic matter in aquatic product processing wastewater.

[0013] The preparation method of the present invention can effectively improve the solubility and dispersibility of the organic base material in water by first subjecting the organic base material to nano-sizing, and then the organic base material is modified by lipophilicity to improve the affinity with insoluble proteins and lipid substances; the base material is compounded with magnetic particles to make it have magnetic recoverability; the composite particles are used for the recovery of protein and lipid substances in aquatic product processing wastewater according to demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The transmission electron microscope image of the magnetic composite particles prepared by the preparation method of the present invention; Figure 2 The Fourier transform infrared spectrum of the magnetic composite particles prepared by the preparation method of the present invention; Figure 3 This is a graph showing the water contact angle test results of the magnetic composite particles prepared by the preparation method of the present invention; Figure 4 The figure is a comparison chart of the difference in oil absorption performance of the magnetic composite particles prepared by the preparation method of the present invention before and after modification. DETAILED DESCRIPTION

[0015] The present invention is described in more detail below in conjunction with specific implementation modes.

[0016] Example A method for preparing magnetic composite particles comprises the following steps: Step 1): Add 10 g of silicate mineral (molecular formula Al2[Si2O5](OH)4·2H2O) to 100 mL of 4% (w / v) NaOH solution, stir at 200 rpm for 1 min, centrifuge at 8000 rpm to remove the supernatant, transfer the precipitate to 100 mL of 2% (v / v) HCl solution, stir at 200 rpm for 1 min, centrifuge at 8000 rpm to remove the supernatant, collect the precipitate, and freeze-dry it for later use.

[0017] Step 2): Take 2 g of chitosan and disperse it in 100 g of NaOH / urea / deionized water (11 / 4 / 85, w / w / w), stir for 5 min (200 rpm), freeze-thaw at -80 °C for 4 h, stir and melt at room temperature, repeat three times, add an equal volume of anhydrous ethanol to the solution, stir at 200 rpm for 10 min, centrifuge at 8000 rpm to remove the supernatant, transfer the precipitate to a dialysis bag, dialyze with deionized water for 3 d, centrifuge at 8000 rpm to remove the supernatant, and freeze-dry the precipitate to obtain chitosan nanowhiskers.

[0018] Step 3): Take 2 g of chitosan nanowhiskers and disperse them in 100 g of NaOH / urea / deionized water (11 / 4 / 85, w / w / w), stir for 5 min (200 rpm), freeze-thaw at -80 ℃ for 4 h, stir and melt at room temperature, repeat three times, add 10 g of Al2[Si2O5](OH)4·2H2O, 2 g of sodium tripolyphosphate (TPP), and 5 g of Ci-ZnFe2O4 to the solution, stir at 200 rpm for 2 h, centrifuge at 8000 rpm to remove the supernatant, transfer the precipitate to a dialysis bag, dialyze with deionized water for 3 d, and freeze-dry the precipitate to obtain magnetic particles before lipophilic modification.

[0019] Step 4): The magnetic particles before lipophilic modification are ultrasonically dispersed in methoxypolyethylene glycol silane (10 g / 100 mL), incubated at 60 °C for 2 h, centrifuged at 8000 rpm to remove the supernatant, and the precipitate is freeze-dried to obtain lipophilic modified magnetic composite particles.

[0020] The magnetic composite particles prepared by the method of the present invention have a core-shell structure, wherein the core is a magnetic Ci-ZnFe2O4 particle and the periphery includes nano-chitosan whiskers. Figure 1 The scanning electron microscopy images of the samples confirmed the presence of round particles with a diameter between 100 and 200 nm.

[0021] Figure 2 The Fourier transform infrared spectrum shows that a large number of Si-O bonds and Si-O-Si bonds are added to the particles after lipophilic modification. These chemical bonds have good lipophilicity and can significantly improve the affinity of the particles for water-insoluble fat-soluble organic matter, thereby improving the efficiency of the particles in separating insoluble organic matter from aquatic product processing wastewater.

[0022] The water contact angle test results are as follows Figure 3 As shown, Figure 3 It shows that after lipophilic modification, the water contact angle of the particles increased from 60° to 120°, indicating that the hydrophobicity was significantly enhanced after modification.

[0023] The comparison of the oil absorption performance of the microparticles prepared by the present invention before and after modification is shown in the figure Figure 4 As shown, Figure 4 The results show that the composite particles after lipophilic modification are black in color with obvious oily sheen, indicating that they have absorbed a large amount of oily substances. The composite particles before modification are light gray in color with no obvious oily sheen, indicating that their adsorption capacity for oily substances is insufficient.

Claims

1. A method for preparing magnetic composite particles, characterized in that: The method comprises the following steps: 1) Add the silicate mineral to the NaOH solution, stir magnetically, centrifuge, remove the supernatant, transfer the precipitate to an equal volume of HCl solution, stir magnetically, centrifuge to remove the supernatant, collect the precipitate and freeze-dry it to obtain the pretreated silicate for standby use; 2) Disperse chitosan in NaOH / urea / deionized water, stir, freeze-thaw, stir and melt at room temperature, repeat freeze-thaw-stirring three times, add an equal volume of anhydrous ethanol to the final solution, stir magnetically, remove the supernatant by centrifugation, transfer the precipitate into a dialysis bag, dialyze with deionized water, remove the supernatant by centrifugation, freeze-dry the precipitate, and obtain chitosan nanowhiskers; 3) Disperse chitosan nanowhiskers in NaOH / urea / deionized water, stir, freeze-thaw, and stir and melt at room temperature, repeat three times, add pretreated silicate minerals, sodium tripolyphosphate, and Ci-ZnFe2O4 to the solution, stir, centrifuge to remove the supernatant, transfer the precipitate into a dialysis bag, dialyze with deionized water, and freeze-dry the precipitate to obtain magnetic particles before lipophilic modification; 4) Ultrasonic dispersion of the magnetic particles before lipophilic modification in methoxypolyethylene glycol silane, constant temperature cross-linking, centrifugation to remove the supernatant, precipitate freeze-drying, and obtain lipophilic modified magnetic composite particles.

2. The method for preparing magnetic composite particles according to claim 1, characterized in that In step 1), the molecular formula of the silicate mineral is Al2[Si2O5](OH)4·2H2O, and the material-liquid ratio of the silicate mineral to the NaOH solution is 1:8-12 in g:mL.

3. The method for preparing magnetic composite particles according to claim 1, characterized in that In step 2) and step 3), NaOH / urea / deionized water are prepared in a weight concentration ratio of 11:4:85, the freeze-thaw temperature is -80°C, and the freeze-thaw time each time is 4 hours.

4. The method for preparing magnetic composite particles according to claim 1, characterized in that In step 2), the mass ratio of chitosan to NaOH / urea / deionized water is 1:45-55.

5. The method for preparing magnetic composite particles according to claim 1, characterized in that In step 3), the mass ratio of chitosan nanowhiskers to NaOH / urea / deionized water is 1:45-55.

6. The method for preparing magnetic composite particles according to claim 1, characterized in that In step 3), 8-12 g of silicate mineral, 1-3 g of sodium tripolyphosphate, and 4-6 g of Ci-ZnFe2O4 are added to every 100 g of NaOH / urea / deionized water.

7. Magnetic composite particles obtained by the preparation method according to any one of claims 1 to 6.

8. Use of the magnetic composite particles according to claim 7 in the treatment of wastewater from aquatic product processing.

9. Use of the magnetic composite particles according to claim 7 for enriching insoluble organic matter in wastewater from aquatic product processing.

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