Functionalized polyamide polymer, preparation method and application thereof, and heavy metal remover

Abstract

The invention discloses a functionalized polyamide polymer, a preparation method and application thereof, and a heavy metal remover, and relates to the field of heavy metal removers, the functionalized polyamide polymer comprises a polyamide main chain formed by a polymerization reaction of piperazine and adipic acid; the first side chain containing carboxyl and the second side chain containing amino are connected to the polyamide main chain. Piperazine and adipic acid are used as reaction monomers, a cyclic structure of piperazine is used for providing rigidity, a methylene chain of adipic acid is used for providing flexibility, a polyamide main chain which is resistant to a strong acid environment and has excellent mechanical strength and chemical stability is obtained, meanwhile, a carboxyl side chain and an amino side chain are introduced to the polyamide main chain, and the polyamide main chain has excellent mechanical strength and chemical stability. The adsorption capacity on heavy metal ions such as Pb < 2 + >, Cu < 2 + >, Mn < 2 + >, Cr < 6 + > and Cd < 2 + > is enhanced, so that the sewage treatment requirements in different fields are met, and the application prospect is wide.

Description

Technical Field

[0001] This invention relates to the field of heavy metal removal agents, and more particularly to a functionalized polyamide polymer, its preparation method and application, and heavy metal removal agents. Background Technology

[0002] With the acceleration of industrialization, heavy metal pollution has become a global environmental problem. Industrial production processes, such as mining, metallurgy, electroplating, battery manufacturing, and chemical industries, generate large amounts of wastewater containing heavy metal ions. These heavy metal ions, such as lead (Pb), are particularly problematic. 2+ ), copper (Cu) 2+ ), manganese (Mn) 2+ ), chromium (Cr) 6+ ), cadmium (Cd 2+ These substances, such as [list of substances], are highly toxic, persistent, and bioaccumulative. Even at very low concentrations, they can cause serious harm to the ecological environment and human health.

[0003] To protect the ecological environment and human health, effective treatment of heavy metal-polluted wastewater is urgently needed. Currently, commonly used methods for treating heavy metal wastewater include chemical precipitation, ion exchange, membrane separation, and adsorption. Among these, adsorption has received widespread attention due to its advantages such as simple operation, low cost, good treatment effect, and the ability to recover heavy metals. Therefore, developing efficient, environmentally friendly, and economical heavy metal adsorption materials is a current research hotspot in the field of heavy metal pollution control. Summary of the Invention

[0004] To address the above problems, this invention provides a functionalized polyamide polymer, its preparation method and application, and a heavy metal removal agent.

[0005] In a first aspect, the present invention provides a functionalized polyamide polymer, comprising:

[0006] The polyamide backbone formed by the polymerization reaction of piperazine and adipic acid; and

[0007] A first side chain containing a carboxyl group and a second side chain containing an amino group are attached to the polyamide backbone.

[0008] Furthermore, the degree of polymerization of the polyamide backbone is 300-700.

[0009] Furthermore, the chemical structural formula of the functionalized polyamide polymer is shown below:

[0010]

[0011] The value of n ranges from 300 to 700.

[0012] Furthermore, the infrared spectrum of the functionalized polyamide polymer has at least the following characteristic peaks:

[0013] 3300cm -1 NH stretching vibration peak, 2935 cm⁻¹ -1 And 2860cm -1 CH stretching vibration peak, 1650 cm⁻¹ -1 C=O stretching vibration peak, 1550 cm⁻¹ -1 NH bending vibration peak, 1250 cm⁻¹ -1 CN stretching vibration peak, 1000cm -1 Piperazine ring vibration peak, 720 cm⁻¹ -1 CH bending vibration peak.

[0014] Secondly, based on the same inventive concept, the present invention provides a method for preparing the functionalized polyamide polymer described in the first aspect, the method comprising the following steps:

[0015] Under an inert gas atmosphere and with the aid of a catalyst, piperazine and adipic acid were added to a first solvent to carry out a polymerization reaction, yielding the PIP-ADA polymer;

[0016] Under an inert gas atmosphere and with the aid of an initiator, the PIP-ADA polymer and acrylic monomer are added to a second solvent for a grafting reaction to obtain the PIP-ADA-COOH polymer.

[0017] The PIP-ADA-COOH polymer, N-hydroxysuccinimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and ethylenediamine were added to a third solvent for amidation reaction to obtain the functionalized polyamide polymer.

[0018] Furthermore, the molar ratio of the piperazine to the adipic acid is (1-2):(1-2);

[0019] The first solvent includes N,N-dimethylacetamide;

[0020] The catalyst includes sodium hypophosphite, and the amount of the catalyst added is 0.3 to 0.7 wt% of the total mass of the piperazine and adipic acid monomers.

[0021] The polymerization reaction includes a prepolymerization stage and a polycondensation stage; the working conditions for the prepolymerization stage include a temperature of 110–120°C and a time of 1–3 hours; the working conditions for the polycondensation stage include a temperature of 150–170°C and a time of 7–9 hours.

[0022] The purification process after the polymerization reaction is completed includes the following steps: the reaction solution is cooled to room temperature and then poured into excess deionized water to precipitate the polymer, followed by filtration, washing, drying and grinding to obtain the PIP-ADA polymer.

[0023] Further, the mass ratio of the PIP-ADA polymer to the acrylic monomer is (4.5-5.5):(1-2);

[0024] The initiator includes ammonium persulfate, and the amount of the initiator added accounts for 2 to 4% of the mass of the acrylic monomer;

[0025] The operating conditions for the grafting reaction include: protection from light, a temperature of 65–75°C, and a time of 3.5–4.5 hours.

[0026] The second solvent includes at least one of water, tetrahydrofuran, and N,N-dimethylformamide;

[0027] The purification process after the grafting reaction includes the following steps: after the reaction solution is cooled to room temperature, the pH is adjusted to 8-9 with 0.8-1.5 mol / L NaOH to completely dissolve the product. Then, the product is reprecipitated with 0.3-0.7 mol / L HCl, filtered, and dried under vacuum to obtain the PIP-ADA-COOH polymer.

[0028] Further, the mass ratio of the PIP-ADA-COOH polymer, the N-hydroxysuccinimide, the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and the ethylenediamine is (2-4):(0.8-1.2):(1-1.5):(0.5-0.8);

[0029] The third solvent includes phosphate buffer;

[0030] The operating conditions for the amidation reaction include: a temperature of 20–30°C and a time of 10–14 hours.

[0031] The purification process after the amidation reaction includes the following steps: the reaction solution is dialyzed in deionized water using a dialysis bag, and then freeze-dried to obtain the functionalized polyamide polymer.

[0032] Thirdly, based on the same inventive concept, this invention provides the application of the functionalized polyamide polymer described in the first aspect or the functionalized polyamide polymer prepared by the preparation method of the functionalized polyamide polymer described in the second aspect in the preparation of heavy metal removal agents and in the removal of heavy metals, wherein the solution for removing heavy metals includes titanium liquid produced by the sulfuric acid process for titanium dioxide.

[0033] Fourthly, based on the same inventive concept, the present invention provides a heavy metal removal agent, comprising the functionalized polyamide polymer described in the first aspect or the functionalized polyamide polymer prepared by the preparation method of the functionalized polyamide polymer described in the second aspect.

[0034] The technical solutions provided in the embodiments of the present invention have at least the following advantages compared with the prior art:

[0035] This invention provides a functionalized polyamide polymer, its preparation method, and its applications as a heavy metal removal agent. The invention utilizes piperazine and adipic acid as reactants, leveraging the cyclic structure of piperazine to provide rigidity and the methylene chain of adipic acid to provide flexibility, resulting in a polyamide backbone resistant to strong acid environments and possessing excellent mechanical strength and chemical stability. Furthermore, carboxyl and amino side chains are introduced onto the polyamide backbone to enhance its resistance to Pb. 2+ Cu 2+ Mn 2+ Cr 6+ Cd 2+ It has the ability to adsorb heavy metal ions, thus meeting the wastewater treatment needs of different fields and has broad application prospects. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0038] Figure 1 Infrared spectra of functionalized polyamide polymers provided in embodiments of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this invention can be purchased commercially or prepared using existing methods. Furthermore, unless otherwise specified or detailed, the steps and parameters involved can be performed according to the existing technology's disclosed processes and parameters for preparing functionalized polyamide polymers, or directly using existing equipment according to the instruction manual. These will not be elaborated upon further in this invention document.

[0041] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to national standards. If no corresponding national standard exists, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0042] Example 1

[0043] This example provides a functionalized polyamide polymer with the following chemical structural formula:

[0044]

[0045] The value of n ranges from 300 to 700.

[0046] The preparation method of the above-mentioned functionalized polyamide polymers includes the following steps:

[0047] (1) Synthesis of polyamide backbone (PIP-ADA)

[0048] Raw material ratio: piperazine (PIP) to adipic acid (ADA) molar ratio: 1:1; solvent: N,N-dimethylacetamide (DMAc); solid content of piperazine and adipic acid added to the solvent: 20wt%.

[0049] Reaction conditions: Catalyst: Sodium hypophosphite, added at 0.5 wt% of the total monomer mass (i.e., piperazine (PIP) and adipic acid (ADA)); Reaction temperature and time: Prepolymerization stage: 120℃, 2 hours; Polycondensation stage: 160℃, 8 hours; Stirring speed: 200 rpm, mechanical stirring throughout; Protective atmosphere: Nitrogen protection; Moisture removal: Water generated is removed by reflux condensation.

[0050] Post-processing: The reaction solution was cooled to room temperature, precipitated in excess deionized water, filtered, washed three times with ethanol, dried under vacuum at 60°C to constant weight, ground, and passed through a 100-mesh sieve to obtain white PIP-ADA powder (i.e., PIP-ADA polymer).

[0051] (2) Carboxyl side branching reaction (-COOH)

[0052] Raw material ratio: PIP-ADA powder: 5g; deionized water: 100mL; acrylic acid monomer (AA): 1.5g; ammonium persulfate (APS) initiator: 0.05g.

[0053] Reaction conditions: Pretreatment: Nitrogen gas was purged for 30 minutes to remove oxygen; Reaction parameters: 70℃, stirring at 300 rpm, free radical graft copolymerization for 4 hours, and the process was carried out in the dark.

[0054] Purification process: After cooling the reaction solution, adjust the pH to 8-9 with 1 mol / L NaOH to completely dissolve the product. Then, redefine the product with 0.5 mol / L HCl, filter, and vacuum dry at 50℃ to obtain the carboxylated intermediate PIP-ADA-COOH (i.e., PIP-ADA-COOH polymer).

[0055] (3) Amino side chain modification (-NH2), amidation reaction

[0056] 4.3.1 Amide reaction

[0057] Raw material ratio: PIP-ADA-COOH: 3g, phosphate buffer (pH=6.0): 80mL, N-hydroxysuccinimide (NHS): 0.9g, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC): 1.2g, ethylenediamine (EDA): 0.6g (molar ratio of EDA to acrylic acid units 1:1.2).

[0058] Reaction conditions: 25℃, continuous stirring for 12 hours.

[0059] Purification of the final product: The reaction solution was dialyzed in deionized water for 48 hours using a dialysis bag (MWCO 3500Da), with the water changed every 8 hours. After freeze-drying, a light yellow FPAM powder (i.e., functionalized polyamide polymer) was obtained, which was sealed and stored in a desiccator for later use.

[0060] Example 2

[0061] This example provides a heavy metal removal agent, namely the functionalized polyamide polymer provided in Example 1.

[0062] Comparative Example 1

[0063] This example provides a heavy metal removal agent, namely the unfunctionalized PIP-ADA polymer in Example 1 (i.e., the intermediate product-PIP-ADA polymer obtained in step 1 of Example 1).

[0064] Comparative Example 2

[0065] This example provides a heavy metal removal agent, namely commercially available wood-based activated carbon (specific surface area 800-1000 m²). 2 / g, iodine value ≥850mg / g), its pretreatment activation includes the following process: 1. Soak in 1mol / L HCl for 12 hours to remove ash and metal impurities; 2. After filtration, wash with deionized water until neutral (pH=6-7); 3. Dry at 105℃ for 12 hours; 4. Grind and pass through a 100-mesh sieve; 5. Activation: Vacuum dry at 150℃ for 2 hours before use.

[0066] Comparative Example 3

[0067] This example provides a heavy metal removal agent, namely titanium sulfate coagulant, whose preparation method includes the following steps: Weigh 2.4g of titanium sulfate (Ti(SO4)2, analytical grade) and dissolve it in 100mL of deionized water; Stock solution concentration: 0.1mol / L (Ti(SO4)2, analytical grade) 4+ Concentration approximately 4.8 g / L; Usage requirements: Prepare and use immediately to avoid hydrolysis and precipitation.

[0068] Test Example 1

[0069] In this example, the functionalized polyamide polymer obtained in Example 1 was analyzed by Fourier Transform Infrared Spectroscopy (FTIR). The test results are shown in Table 1 and... Figure 1 As shown.

[0070] The successful introduction of the functional group was verified by infrared spectroscopy, and the main characteristic peaks are shown in Table 1 below:

[0071] Table 1

[0072]

[0073]

[0074] Test Example 2

[0075] This test case examines the performance of the heavy metal removal agents provided in Example 2 and Comparative Examples 1-3 above, specifically including the following processes:

[0076] 1. Simulated wastewater preparation

[0077] Based on a survey of wastewater from the sulfuric acid process for titanium dioxide production, this study focuses on simulating two key stages: waste acid after hydrolysis and washing wastewater after calcination.

[0078] Characteristics of hydrolysis waste acid: pH value: 1.0-2.0; Total dissolved solids (TDS): 50-80 g / L; Main ionic component: Fe 3 + 2-5 g / L; Ti 4+ : 0.5-1.5g / L; Al 3+ 0.3-1.0 g / L; SO4 2- 30-50g / L.

[0079] Characteristics of calcination washing wastewater: pH value: 5.0-6.5; TDS: 2-5 g / L; Main ionic component: Fe 2+ / Fe 3+ 50-200 mg / L; Ca 2+ 100-300 mg / L; Mg 2+ : 50-150mg / L; Suspended solids (SS): 100-300mg / L.

[0080] The heavy metal stock solution (1000 mg / L) is prepared as follows:

[0081] Preparation of Pb2+ stock solution: Weigh 1.599g of lead nitrate (Pb(NO3)2, analytical grade) and dissolve it in 1L of deionized water; Stabilization measures: Add 2mL of concentrated nitric acid to acidify and prevent hydrolysis.

[0082] As 3+ Preparation method of stock solution: Weigh 1.320g sodium arsenite (NaAsO2, highly toxic) and dissolve it in 1L of deionized water; Precautions: Prepare and use immediately.

[0083] Cr 6+ Preparation of stock solution: Weigh 2.829g of potassium dichromate (K2Cr2O7, analytical grade) and dissolve it in 1L of deionized water; Storage conditions: Store in a polyethylene bottle away from light.

[0084] Simulated wastewater preparation scheme

[0085] The simulated waste acid solution (pH=1.5) after hydrolysis is as follows:

[0086] 1. Preparation of basic salt solution: Fe2(SO4)3·9H2O: 22.5g / L; TiOSO4: 2.0g / L; Al2(SO4)3·18H2O: 3.0g / L; MgSO4·7H2O: 1.5g / L; CaCl2: 1.0g / L.

[0087] 2. pH adjustment: Add 98% H2SO4 dropwise to adjust the pH to 1.5 (conductivity approximately 85 mS / cm).

[0088] 3. Heavy metal addition: Transfer the stock solution separately to allow Pb to be added. 2+ As 3+ Cr 6+ The initial concentration was 50 mg / L.

[0089] 4. Volumetric storage: Bring the volume to 1L, degas using ultrasound for 10 minutes, and use immediately after preparation.

[0090] The simulated solution of washing wastewater after calcination (pH=5.5) is as follows:

[0091] 1. Preparation of basic salt solutions: FeSO4·7H2O: 0.5g / L; Al2(SO4)3·18H2O: 0.2g / L; MgSO4·7H2O: 0.3g / L; CaCl2: 0.2g / L; Na2SO4: 1.0g / L.

[0092] 2. pH adjustment: Fine-tune to pH 5.5 (conductivity approximately 5 mS / cm) using 0.1 mol / L NaOH or 0.1 mol / L HCl.

[0093] 3. Heavy metal addition: Transfer the stock solution separately to allow Pb to be added. 2+ As 3+ Cr 6+ The initial concentration was 30 mg / L.

[0094] 4. Simulated suspended solids: Add 200 mg of kaolin (particle size <10 μm) to simulate suspended solids, and stir well.

[0095] Water quality parameter verification: The simulated wastewater was measured using a pH meter, conductivity meter, and turbidity meter, and the actual concentration of heavy metals was confirmed using ICP-MS. The deviation should be <5%.

[0096] 2. Experimental methods and procedures

[0097] Reaction vessel: Specification: 250mL stoppered conical flask (high borosilicate glass); Pretreatment: Soak in 1mol / L HNO3 for 2 hours before each use, then rinse thoroughly.

[0098] Reaction conditions control: Shaking equipment: constant temperature air bath shaker (150 rpm, 25±1℃); Solid-liquid separation: vacuum filtration using a 0.45 μm mixed cellulose ester filter membrane; Filter membrane pretreatment: pre-soaking in deionized water for 30 min to remove soluble impurities.

[0099] The standard operating procedure is as follows:

[0100] Heavy metal removal agent addition: Accurately weigh 0.25g of heavy metal removal agent (experimental group or control group) into an Erlenmeyer flask (dosage 1g / L).

[0101] Adding simulated wastewater: Take 250 mL of simulated wastewater (pH pre-adjusted to the target value) and slowly add it along the bottle wall to avoid loss of heavy metal removal agent.

[0102] Real-time pH monitoring: Insert a pH electrode, monitor in real time, and fine-tune with a small amount of 0.1 mol / L HCl / NaOH every 30 minutes to ensure pH fluctuation < ±0.2 units.

[0103] Oscillating adsorption: After sealing, place in a shaker and time the reaction for 4 hours (according to preliminary experiments, the adsorption equilibrium time is 3.5 hours).

[0104] Standing and sampling: After the reaction is complete, let stand for 10 minutes, take 5 mL of supernatant, filter it through a 0.45 μm filter membrane, and then immediately acidify and store it.

[0105] Comparative experimental design

[0106] Experiment 1: Performance comparison of different heavy metal removal agents under acidic conditions is as follows.

[0107] Experimental conditions: pH = 3.0 ± 0.1, and the simulated wastewater was hydrolyzed waste acid simulation solution.

[0108] Heavy metal concentration: Pb 2+ As 3+ Cr 6+ The initial concentration was 50 mg / L.

[0109] Heavy metal removal agent dosage: 1.0 g / L.

[0110] Reaction conditions: 25.0±0.5℃, reaction time 4.0 hours.

[0111] Key points of operation:

[0112] 1. Pretreatment of the heavy metal removal agent provided in Example 2 and Comparative Example 1: After vacuum drying at 60°C for 2 hours, the agent was placed in a desiccator for cooling.

[0113] 2. Special treatment for activated carbon: An additional 30 minutes of ultrasonic dispersion (40kHz, 200W) is added to eliminate bubble interference.

[0114] 3. Coagulant operation: Mix quickly for 1 minute (300 rpm); flocculate by slow stirring for 15 minutes (50 rpm); allow to settle for 30 minutes and then filter the supernatant.

[0115] 4. Parallel experiments: Three parallel samples were set up for each group, and a blank control was also set up.

[0116] Experiment 2: Effect of pH on the adsorption performance of FPAM (i.e., the heavy metal removal agent provided in Example 2)

[0117] Heavy metal removal agent: FPAM only (i.e., the heavy metal removal agent provided in Example 2).

[0118] pH gradient: 2.0, 4.0, and 7.0.

[0119] Simulated wastewater: Hydrolyzed waste acid simulation solution was used uniformly, with an initial heavy metal concentration of 50 mg / L.

[0120] pH adjustment methods:

[0121] 1. pH = 2.0: Adjust directly with 98% H2SO4, and control the conductivity at 90 ± 5 mS / cm.

[0122] 2. pH = 4.0: Adjust slowly dropwise with 0.5 mol / L NaOH to avoid localized over-alkalinity and precipitation.

[0123] 3. pH = 7.0: First adjust to near neutral with 1 mol / L NaOH, then fine-tune to 7.0 ± 0.1 with 0.1 mol / L NaOH.

[0124] Analysis and testing methods

[0125] The heavy metal concentration was determined as follows:

[0126] Instrument selection: Inductively coupled plasma mass spectrometry (ICP-MS, Agilent 8900) or atomic absorption spectrometry (AAS, flame method).

[0127] Sample pretreatment: Add 1% (v / v) analytical grade HNO3 to the filtrate for acidification, store in the dark at 4°C, and complete the detection within 24 hours.

[0128] Standard curve: Prepare a series of standard solutions of 0, 10, 50, 100, and 500 μg / L, with matrix matching, and correlation coefficient R. 2 >0.999.

[0129] Quality control: For each batch of samples, standard substances and spiked recovery samples are inserted, and the recovery rate is controlled at 90-110%.

[0130] FTIR characterization verification

[0131] Sample preparation method: The adsorption-saturated FPAM was vacuum dried at 50℃ and mixed with KBr at a mass ratio of 1:100 and compressed into tablets.

[0132] Test conditions: Scanning range 4000-400cm -1 4cm resolution -1 The number of scans was 32.

[0133] Key points of analysis: Observe the -COO after adsorption. - (1650cm -1 ) and -NH3 + (1550cm -1 Peak displacement and intensity changes.

[0134] 3. Experimental Test Results

[0135] Table 2 shows a comparison of the removal performance of different heavy metal removal agents under acidic conditions (pH = 3.0 ± 0.1).

[0136] Table 2

[0137]

[0138] As shown in Table 2:

[0139] 1. The heavy metal removal agent provided in Example 2 has the best overall performance: it shows a high removal rate (85.4-91.8%) for all three heavy metals.

[0140] 2. Titanium sulfate for As 3+ Special effect: Removal rate reaches 97.0%, derived from Ti 4+ Specific complexation and coprecipitation of hydrolysis products.

[0141] 3. Activated carbon has moderate performance: It is effective against Pb. 2+ The removal effect was good (75.0%), but it was not effective against As. 3+ The removal rate was low (39.6%).

[0142] 4. The limited effectiveness of unfunctionalized polyamides: This verifies the crucial role of functional groups.

[0143] The effect of pH value on the adsorption performance of the FPAM heavy metal removal agent provided in Example 2 is shown in Table 3.

[0144] Table 3

[0145]

[0146]

[0147] As shown in Table 3:

[0148] 1. Under strongly acidic conditions (pH 2.0): the carboxyl group mainly exists in the form of -COOH, with weak coordination ability. The amino group is fully protonated to -NH3. + It has a good removal effect on anionic pollutants. Cr 6+ The removal rate was abnormally high, and a small amount of Cr was confirmed to be present. 6+ Fe 2+ Impurities reduced to Cr 3+ The phenomenon.

[0149] 2. Under weakly acidic conditions (pH 4.0): The carboxyl group dissociates into -COO-, enhancing its coordination ability. The amino group retains a certain degree of protonation. The synergistic effect of electrostatic adsorption and coordination results in optimal overall performance.

[0150] 3. Neutral conditions at pH 7.0: Carboxyl groups are completely dissociated, affecting Pb. 2+ It has the strongest coordination ability. Deprotonation of the amino group affects As... 3+ Electrostatic adsorption disappears. The isoelectric point of FPAM is approximately pH 6.5-7.0.

[0151] In summary, the embodiments of this invention provide a functionalized polyamide polymer, its preparation method and application, and a heavy metal removal agent. This invention utilizes piperazine and adipic acid as reactants, leveraging the cyclic structure of piperazine to provide rigidity and the methylene chain of adipic acid to provide flexibility, to obtain a polyamide backbone resistant to strong acid environments and possessing excellent mechanical strength and chemical stability. Simultaneously, carboxyl and amino side chains are introduced onto the polyamide backbone to enhance its resistance to Pb. 2+ Cu 2+ Mn 2 + Cr 6+ Cd 2+ It has the ability to adsorb heavy metal ions, thus meeting the wastewater treatment needs of different fields and has broad application prospects.

[0152] Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0153] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A functionalized polyamide polymer, characterized in that, include: The polyamide backbone is formed by the polymerization reaction of piperazine and adipic acid; as well as A first side chain containing a carboxyl group and a second side chain containing an amino group are attached to the polyamide backbone.

2. The functionalized polyamide polymer according to claim 1, characterized in that, The degree of polymerization of the polyamide backbone is 300-700.

3. The functionalized polyamide polymer according to claim 1, characterized in that, The chemical structural formula of the functionalized polyamide polymer is shown below: The value of n ranges from 300 to 700.

4. The functionalized polyamide polymer according to claim 1, characterized in that, The infrared spectrum of the functionalized polyamide polymer has at least the following characteristic peaks: 3300cm -1 NH stretching vibration peak, 2935 cm⁻¹ -1 And 2860cm -1 CH stretching vibration peak, 1650 cm⁻¹ -1 C=O stretching vibration peak, 1550 cm⁻¹ -1 NH bending vibration peak, 1250 cm⁻¹ -1 CN stretching vibration peak, 1000cm -1 Piperazine ring vibration peak, 720 cm⁻¹ -1 CH bending vibration peak.

5. A method for preparing a functionalized polyamide polymer according to any one of claims 1 to 4, characterized in that, The preparation method of the functionalized polyamide polymer includes the following steps: Under an inert gas atmosphere and with the aid of a catalyst, piperazine and adipic acid were added to a first solvent to carry out a polymerization reaction to obtain the PIP-ADA polymer; Under an inert gas atmosphere and with the aid of an initiator, the PIP-ADA polymer and acrylic monomer are added to a second solvent for a grafting reaction to obtain the PIP-ADA-COOH polymer. The PIP-ADA-COOH polymer, N-hydroxysuccinimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and ethylenediamine were added to a third solvent for amidation reaction to obtain the functionalized polyamide polymer.

6. The method for preparing the functionalized polyamide polymer according to claim 5, characterized in that, The molar ratio of the piperazine to the adipic acid is (1-2):(1-2); The first solvent includes N,N-dimethylacetamide; The catalyst includes sodium hypophosphite, and the amount of the catalyst added is 0.3 to 0.7 wt% of the total mass of the piperazine and adipic acid monomers. The polymerization reaction includes a prepolymerization stage and a polycondensation stage; the working conditions for the prepolymerization stage include a temperature of 110–120°C and a time of 1–3 hours; the working conditions for the polycondensation stage include a temperature of 150–170°C and a time of 7–9 hours. The purification process after the polymerization reaction is completed includes the following steps: the reaction solution is cooled to room temperature and then poured into excess deionized water to precipitate the polymer, followed by filtration, washing, drying and grinding to obtain the PIP-ADA polymer.

7. The method for preparing functionalized polyamide polymers according to claim 5, characterized in that, The mass ratio of the PIP-ADA polymer to the acrylic monomer is (4.5–5.5):(1–2). The initiator includes ammonium persulfate, and the amount of the initiator added accounts for 2 to 4% of the mass of the acrylic monomer; The operating conditions for the grafting reaction include: protection from light, a temperature of 65–75°C, and a time of 3.5–4.5 hours. The second solvent includes at least one of water, tetrahydrofuran, and N,N-dimethylformamide; The purification process after the grafting reaction includes the following steps: after the reaction solution is cooled to room temperature, the pH is adjusted to 8-9 with 0.8-1.5 mol / L NaOH to completely dissolve the product. Then, the product is reprecipitated with 0.3-0.7 mol / L HCl, filtered, and dried under vacuum to obtain the PIP-ADA-COOH polymer.

8. The method for preparing the functionalized polyamide polymer according to claim 5, characterized in that, The mass ratio of the PIP-ADA-COOH polymer, the N-hydroxysuccinimide, the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and the ethylenediamine is (2-4):(0.8-1.2):(1-1.5):(0.5-0.8). The third solvent includes phosphate buffer; The operating conditions for the amidation reaction include: a temperature of 20–30°C and a time of 10–14 hours. The purification process after the amidation reaction includes the following steps: the reaction solution is dialyzed in deionized water using a dialysis bag, and then freeze-dried to obtain the functionalized polyamide polymer.

9. The application of a functionalized polyamide polymer according to any one of claims 1 to 4, or a functionalized polyamide polymer prepared by the method of any one of claims 5 to 8, in the preparation of heavy metal removal agents and in the removal of heavy metals, characterized in that, The solution from which heavy metals are to be removed includes titanium liquid produced from titanium dioxide produced by the sulfuric acid process.

10. A heavy metal removal agent, characterized in that, The functionalized polyamide polymers include any one of claims 1 to 4 or functionalized polyamide polymers prepared by the method of any one of claims 5 to 8.

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