Ligand-modified resin-based composite complex breaker, preparation method, and application thereof

Abstract

The present invention discloses a kind of resin-based composite decomposing agent based on ligand modification, preparation method and application thereof.Described method includes resin pretreatment, resin modification, crystal growth and incremental load four steps, D201 strong basic anion exchange resin is first modified by the DMF solution of terephthalic acid to form surface modified resin, then the surface modified resin is placed in the DMF solution of iron ion, heating and stirring reaction prepares the composite material of resin surface crystal growth MIL-101 (Fe) nano material, then adds the DMF solution of terephthalic acid into the system, continues oil bath heating and stirring reaction, prepares resin-based composite adsorbent.MIL-101 (Fe) loading capacity of the decomposing agent of the present invention is controllable, and it shows excellent decomposing performance to heavy metal complex, has stable removal efficiency in treating electroplating wastewater, and has broad application prospect in electroplating wastewater treatment field.

Description

Technical Field

[0001] The present invention relates to the technical field of complex breakers for water treatment, in particular to a ligand-modified resin-based composite complex breaker, a preparation method and application thereof. Background Art

[0002] Heavy metal pollution in water bodies is a very prominent type of pollution in the current global complex water pollution problem, which is common in electroplating, electronics and metallurgical industries. The composition of heavy metal wastewater is very complex. - ) wastewater and acid-base wastewater, heavy metal wastewater can be classified according to the heavy metal elements contained in it, and can generally be divided into chromium-containing, nickel-containing, cadmium-containing, copper-containing, zinc-containing, gold-containing, silver-containing wastewater, etc. Compared with other types of environmental pollution, heavy metal pollution has its own significant characteristics: (1) it can be enriched and difficult to control; (2) it is highly toxic and harmful; (3) it is widely distributed and easy to transform. Heavy metal ions usually form complexes with cyanide, citric acid, EDTA or organic matter. Most complexed heavy metals have high water solubility and can exist stably in a wide pH range. Existing chemical neutralization and precipitation processes are difficult to remove them, and the effluent cannot meet the emission standard requirements. Therefore, the development of new water treatment technologies for the efficient treatment of complexed heavy metal wastewater is an important issue in the field of water pollution control and water environment protection.

[0003] At present, the commonly used treatment technologies for complex heavy metal wastewater mainly include chemical precipitation, redox method, solvent extraction method, adsorption method, membrane separation method, ion exchange method and biological treatment method. Chelate precipitation method in chemical precipitation method is an excellent heavy metal complex treatment method developed in recent years. This method is not affected by the complexing agent during the wastewater treatment process, has a high capture efficiency for heavy metal ions, and the treated wastewater can meet the discharge standards. At the same time, the sludge generation speed is fast and stable, the amount is small, the water content is low, and no secondary pollution will be generated. In addition, the adsorption method has attracted widespread attention for its advantages such as simple operation and energy saving. However, the adsorption method has problems such as short service life of the adsorbent, difficulty in regeneration after heavy metal adsorption saturation, and difficulty in recovering heavy metal resources. Therefore, the development of new water treatment technology combining complex breaking and adsorption is of great significance for the deep treatment of complex heavy metal wastewater.

[0004] In recent years, iron ions (Fe 3+ ) has shown great application potential in achieving the decomplexation of heavy metal complexes. 3+ Displacing metal ions in complexed heavy metals to form more stable iron-containing complexes can decomplex and liberate heavy metal ions without destroying the ligands (e.g., EDTA). However, in actual applications, due to the high content of organic ligands in wastewater, excessive amounts of Fe salts need to be added, and the pH requirement is high.

[0005] Metal-organic framework materials (MOFs) have unique metal-ligand double exchange properties, such as Fe-based MOFs materials (MIL-101(Fe)), which form new MOFs structures. They essentially utilize the substitution effect between metal ions and the coordination stability between ligands and metal ions, and show excellent application potential in post-synthesis modification of materials. In addition, MOFs materials themselves have the characteristics of porous structure, large specific surface area, multiple metal sites, diverse structure and easy modification. They have been widely used in gas adsorption, storage and separation, electrode materials, and catalysis. However, MIL-101(Fe), as a typical MOFs material, usually exists in the form of powder. These extremely fine particles are not conducive to processing and recycling during the separation process, and have poor stability, making them difficult to put into practical engineering applications. Although supports such as zeolites, alumina balls, ceramics, and porous resins can be used to load MOFs, the porous resin-metal organic framework composite adsorbents prepared by the in-situ deposition method reported previously are often only capable of adsorption (CN201611216476), and struggle to decomplex complexed heavy metals, resulting in low heavy metal ion recovery efficiency. Furthermore, the existing technology suffers from a cumbersome reaction process, making it difficult to effectively regulate the loading of MOF nanomaterials. This is fundamentally due to the fact that the heterogeneous nucleation rate of the nanomaterial is much lower than its homogeneous nucleation rate, making it difficult to effectively load the nanomaterial on the resin support.

[0006] Macroporous, strongly alkaline styrene-based anion exchange resin (D201) has two configurations, including hydroxide and chloride. The presence of highly reactive ammonium salt functional groups gives D201 strong anion exchange removal performance. Due to its uniform pore size and high mechanical strength, it has the potential to be used as a carrier for nanoparticle-type water treatment agents. However, during the nucleation process of nanoparticles, the participation of organic ligands in metal coordination is the key to the crystal nucleation and growth reaction. In the process of using resin as a carrier to prepare nanocomposites, the heterogeneous nucleation rate of nanomaterials is much lower than their homogeneous nucleation rate, which makes it difficult to effectively load the nanomaterials on the resin carrier, making it difficult to increase the loading amount of nanomaterials. Summary of the Invention

[0007] The purpose of the present invention is to provide a ligand-modified resin-based composite complex breaker, a preparation method and application thereof.

[0008] The technical solutions for achieving the purpose of the present invention are as follows:

[0009] The preparation method of the ligand-modified resin-based composite complex breaker is based on the strategy of ligand modification and seed growth, and includes the following steps:

[0010] S1: Resin pretreatment

[0011] The D201 resin was pretreated by repeated soaking in saturated salt water, dilute hydrochloric acid, sodium hydroxide solution and water, and finally the resin was rinsed;

[0012] S2: Resin modification

[0013] The pretreated resin is added to a terephthalic acid N,N-dimethylformamide (DMF) solution, shaken at a constant temperature and washed with water to form a surface-modified resin;

[0014] S3: Crystal Growth

[0015] The surface-modified resin is placed in a DMF solution containing iron ions, and heated and stirred at 80-140° C. to prepare a composite material with MIL-101 (Fe) nanomaterials crystallized and grown on the resin surface.

[0016] S4: Incremental load

[0017] A DMF solution of terephthalic acid is added to the system after the S3 reaction, and the heating and stirring reaction is continued. After filtering, washing and drying, a resin-based composite complex breaker is obtained.

[0018] Furthermore, in S1, the particle size of the D201 resin is 0.315 to 1.25 mm.

[0019] Furthermore, in S1, the concentration of dilute hydrochloric acid is 3-5%, the concentration of sodium hydroxide solution is 2-4%, the number of immersions is 2-4 times, the immersion time is 2-12 hours, and the pH of the discharged water is rinsed to 8-11.

[0020] Furthermore, in S2 or S4, the concentration of the DMF solution of terephthalic acid is 5 to 40 mmol / L, the temperature for constant shaking is 5 to 40° C., and the treatment time is 4 to 24 hours.

[0021] Furthermore, in S3, the dosage of the surface-modified resin is 5 to 50 g / L.

[0022] Furthermore, in S3, in the DMF solution of iron ions, the iron source is one or any combination of two or more of ferrous chloride, ferric chloride, ferric nitrate, ferrous ammonium sulfate, and ammonium ferric sulfate, the concentration of iron ions is 2.5 to 20 mmol / L, the heating method is an oil bath, and the stirring reaction time is 6 to 24 hours.

[0023] Furthermore, in S4, the drying treatment temperature is 40-100°C.

[0024] The present invention provides a resin-based composite complex breaker prepared by the above preparation method.

[0025] Furthermore, the present invention provides the use of the resin-based composite complex breaker in complex breaking treatment of electroplating wastewater.

[0026] Furthermore, the electroplating wastewater is common electroplating wastewater, such as copper-containing or nickel-containing wastewater produced by ligands such as ethylenediaminetetraacetic acid, citric acid, tartaric acid or tannic acid.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) The large ion exchange capacity and high efficiency of the chlorine-type resin D201 are fully utilized to improve the uniform distribution of the ligand terephthalic acid on the resin carrier;

[0029] (2) The MIL-101(Fe) nanocrystals prepared by the seed growth method during the synthesis process accelerated the heterogeneous nucleation rate of the nanomaterial, which facilitated the controllable regulation of the MIL-101(Fe) nanocrystal loading in the subsequent synthesis steps;

[0030] (3) The cost of the resin carrier is low, the synthesis method of seed crystal growth is simple, the conditions are mild, and it is easy to mass produce;

[0031] (4) By controlling the D201 resin carrier pretreatment sequence, resin type, organic ligand selection, and incremental loading steps, the loading amount of MIL-101(Fe) nanocrystals was increased, thereby improving the decomposition performance of the resin-based composite decomposition agent;

[0032] (5) The resin-based composite decomplexing agent of the present invention exerts the function of MIL-101 (Fe) metal-ligand double exchange, has good decomplexing performance for heavy metal complexes, and has high treatment efficiency and wide applicability in the deep treatment of electroplating wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a SEM image of the resin-based composite network breaker prepared in Example 1;

[0034] Figure 2 This is a comparison chart of the EDTA-Cu complex breaking effects of the resin-based composite complex breaking agents prepared in Example 1 and Comparative Examples 1-4. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific embodiments and accompanying drawings.

[0036] Example 1

[0037] The resin-based composite complex breaker is prepared based on the strategy of ligand modification and seed growth, which includes the following steps:

[0038] S1: Resin pretreatment

[0039] D201 resin with a particle size of 0.315-1.25 mm was pretreated by repeated soaking in saturated salt water, 3% dilute hydrochloric acid, 2% sodium hydroxide solution and clean water. The soaking times were 2 times and the soaking time was 2 hours. Finally, the resin was rinsed until the pH of the discharged water was 8.

[0040] S2: Resin modification

[0041] The pretreated resin was added to a 5 mmol / L terephthalic acid DMF solution, shaken at 5°C for 24 hours, and washed with water to form a surface-modified resin.

[0042] S3: Crystal Growth

[0043] The surface-modified resin was added at a dosage of 5 g / L in a DMF solution of ferrous chloride (FeCl2) with an iron ion concentration of 2.5 mmol / L. After heating and stirring in an 80°C oil bath for 24 hours, a composite material with MIL-101(Fe) nanomaterials crystallized and grown on the resin surface was prepared.

[0044] S4: Incremental load

[0045] A 5 mmol / L DMF solution of terephthalic acid was added to the S3 system, and the mixture was heated and stirred at 40°C for 24 hours. After filtration, washing, and drying at 40°C, a composite material of D201 resin loaded with MIL-101 (Fe) (referred to as resin-based composite decomplexing agent) was obtained and marked as No. 1.

[0046] The morphology of the samples was characterized using scanning electron microscopy (SEM). Figure 1 The results showed that MIL-101(Fe) was successfully loaded onto the D201 resin. After digestion, the loading capacity was characterized by inductively coupled plasma chromatography. The results showed that the effective loading capacity of MIL-101(Fe) was 3.5 wt%.

[0047] Resin-based composite decomplexer No. 1 was added to electroplating wastewater containing copper (EDTA-Cu) produced by the ligand ethylenediaminetetraacetic acid (EDTA-Cu). The EDTA-Cu concentration was 10 ppm, the sulfate concentration was 500 ppm, and the pH was 3. Compared with resin D201, the adsorption removal capacity of the resin composite adsorbent loaded with MIL-101(Fe) was significantly improved, from the original 5% to over 60% (67%). Sample No. 1 also exhibited strong resistance to anionic ion interference and maintained good stability after five cycles of reaction, with a MIL-101(Fe) shedding rate of <0.01%.

[0048] Comparative Example 1

[0049] This comparative example is basically the same as Example 1, except that in S1, the pretreatment order of the D201 resin carrier is repeated immersion in saturated salt water, sodium hydroxide solution, dilute hydrochloric acid and water, and finally the resin is rinsed. The prepared resin-based composite decomposing agent is marked as No. 2. The MIL-101 (Fe) loading of No. 2 composite decomposing agent is 1.5wt%, and the decomposing efficiency of the wastewater containing EDTA-Cu is 35%. The specific data is shown in Figure 2 This indicates that the pretreatment order of D201 resin will affect the decomposition efficiency of the final resin-based composite decomposition agent.

[0050] Comparative Example 2

[0051] This comparative example is basically the same as Example 1, except that in S1, the D201 resin carrier is replaced with a cationic exchange resin (D001). The prepared resin-based composite decomposing agent is labeled No. 3. The MIL-101 (Fe) loading of No. 3 composite decomposing agent is 0.15 wt % and the decomposing efficiency of the wastewater containing EDTA-Cu is 20%. The specific data are shown in Figure 2 This indicates that the type of resin will affect the decomposition efficiency of the resin-based composite decomposition agent.

[0052] Comparative Example 3

[0053] This comparative example is basically the same as Example 1, except that in S2, the organic ligand is trimesic acid. The prepared resin-based composite decomposing agent is marked as No. 4. The MIL-101 (Fe) loading of No. 4 composite decomposing agent is 2.5wt%, and the decomposing efficiency of the wastewater containing EDTA-Cu is 42%. The specific data is shown in Figure 2 This indicates that the choice of organic ligand will affect the decomposition efficiency of the final resin-based composite decomposition agent.

[0054] Comparative Example 4

[0055] This comparative example is basically the same as Example 1, except that the incremental loading process of S4 is eliminated. The prepared resin-based composite decomposing agent is labeled No. 5. The MIL-101 (Fe) loading of No. 5 composite decomposing agent is 0.05 wt % and the decomposing efficiency of EDTA-Cu wastewater is 12%. Figure 2 This indicates that the incremental loading of S4 can further increase the MIL-101(Fe) loading amount of the resin-based composite decomplexer.

Claims

1. A method for preparing a ligand-modified resin-based composite complex breaker, characterized in that: The steps include: S1: Resin pretreatment The D201 resin was pretreated by repeated soaking in saturated salt water, dilute hydrochloric acid, sodium hydroxide solution and water, and finally the resin was rinsed; S2: Resin modification The pretreated resin is added to a DMF solution of terephthalic acid, shaken at a constant temperature and washed with water to form a surface-modified resin; S3: Crystal Growth The surface-modified resin was placed in a DMF solution containing iron ions and heated and stirred at 80-140°C to prepare a composite material with MIL-101(Fe) nanomaterials crystallized and grown on the resin surface. S4: Incremental load A DMF solution of terephthalic acid is added to the system after the S3 reaction, and the heating and stirring reaction is continued. After filtering, washing and drying, a resin-based composite complex breaker is obtained.

2. The preparation method according to claim 1, wherein In S1, the particle size of D201 resin is 0.315~1.25mm.

3. The preparation method according to claim 1, characterized in that In S1, the concentration of dilute hydrochloric acid is 3-5%, the concentration of sodium hydroxide solution is 2-4%, the number of immersions is 2-4 times, the immersion time is 2-12 hours, and the pH of the discharged water is rinsed to 8-11.

4. The preparation method according to claim 1, wherein In S2 or S4, the concentration of the DMF solution of terephthalic acid is 5 to 40 mmol / L; in S2, the temperature of the constant temperature shaking is 5 to 40°C, and the treatment time is 4 to 24 hours.

5. The preparation method according to claim 1, wherein In S3, the dosage of the surface-modified resin is 5~50 g / L.

6. The preparation method according to claim 1, wherein In S3, in the DMF solution of iron ions, the iron source is one or any combination of two or more of ferrous chloride, ferric chloride, ferric nitrate, ferrous ammonium sulfate, and ammonium ferric sulfate, the concentration of iron ions is 2.5-20 mmol / L, the heating method is an oil bath, and the stirring reaction time is 6-24 hours.

7. The preparation method according to claim 1, characterized in that In S4, the drying temperature is 40-100°C.

8. The resin-based composite network breaker obtained by the preparation method according to any one of claims 1 to 7.

9. Use of the resin-based composite complex breaker as claimed in claim 8 in complex breaking treatment of electroplating wastewater.

10. The use according to claim 9, characterized in that The electroplating wastewater is copper-containing or nickel-containing wastewater produced by containing ethylenediaminetetraacetic acid, citric acid, tartaric acid or tannic acid ligands.

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