A method for rapidly treating DEP in wastewater

Abstract

This invention provides a method for rapidly treating DEP in polluted water. The steps are as follows: a) Place an appropriate amount of tetrahydrofuran (THF) in a beaker of suitable capacity, ensuring the beaker's volume does not exceed three times the volume of the THF; b) Add an appropriate amount of PVC resin to the beaker in a suitable ratio; c) Seal the resulting homogeneous solution and sonicate it in pure water for 10-15 minutes. Once the solution is clear, remove it; d) Add the resulting highly efficient removal solution to the DEP-polluted water, remove the treated suspended solids, and allow the THF to evaporate before the water treatment process is complete. Compared to directly using PVC resin to remove DEP and other organic pollutants from water, this method significantly increases removal efficiency, saves treatment time, and makes the treated pollutants easier to remove.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method for instantaneously treating DEP in wastewater. Background Technology

[0002] Plastics are materials formed by the chemical synthesis of polymers, and various plastic products derived from them are increasingly used in human life. Among them, polyvinyl chloride (PVC) plastic products are widely used, such as plastic bottles, billboards, and gloves. PVC plastic is a polymer synthesized from PVC monomers through industrial processes such as distillation, polymerization, stripping, and drying. Due to the high chlorine content of PVC plastic, the recycling of its waste and additives is challenging. Different performance requirements exist for plastisol in the production of vinyl flooring, carpets, medical gloves, stickers, automobiles, and packaging. Each component entering the slurry or organic alcohol will have a direct or indirect impact. Among them, plasticizers are two major components. PVC is a specialized resin that differs not only from others in its manufacturing process but also in its usage and manufacturing applications. Compared to suspension-grade GP, it has a larger particle size and better dispersion. Polyvinyl chloride (PVC) is the world's third-largest thermoplastic synthetic plastic. PVC in the environment contains various additives. Different types of additives are added during production to improve extrusion resistance and extend the polymer's lifespan. These additive monomers are encapsulated within the polymer matrix but do not chemically bind to the polymer. Therefore, the plastic may interact with organic pollutants in the environment through physical processes. Studies have shown that PVC ranks second in adsorption capacity among four common microplastics in the environment and can also act as a carrier for heavy metals such as zinc and copper. Therefore, research on the adsorption of pollutants by PVC is essential. Some studies suggest that additives are compounds that must be added to the polymer (synthesized) during the plastic molding process because polymer monomers more easily bind to additives. Therefore, the adsorption of additives by plastic polymer monomers and the fixation mechanism of additives during plasticization deserve further investigation.

[0003] In the production and processing of plastic products, compounds are often added in specific formulations to improve polymer performance and extend service life; these compounds are collectively referred to as additives. Flexible polyvinyl chloride (PVC) products, such as packaging / greenhouse films, toys, medical infusion tubing, wires, cables, and flooring materials, may contain high levels of phthalates. Phthalate plasticizers are endocrine disruptors and may have adverse effects on human and animal development and reproduction. Large amounts of plastic waste eventually enter the marine environment, often releasing additives during their natural aging and decomposition. Currently, many compounds used as plastic additives have been detected in major estuaries and seawater worldwide, with diethyl phthalate (DET) showing the highest detection frequency. Phthalate esters are a major component of PVC plastics, primarily functioning to weaken secondary bonds between molecules, increase molecular fluidity and plasticity, reduce crystallinity, and make the plastic more flexible. Existing technologies for removing phthalates from water mainly include adsorption, membrane separation, biodegradation, and photocatalysis. Low reaction rates, difficulties in recovering and treating adsorbent materials, and potential secondary pollution limit the widespread application of most technologies. Adsorption technology is the most widely used, and in actual wastewater treatment, sequencing batch adsorption (SBI) is used to efficiently remove pollutants from water. However, most adsorbent materials used in adsorption technologies are time-consuming and complex to manufacture, and research on the rapid adsorption and removal of phthalates from water is scarce. Diethyl phthalate (DEP) is one of the most representative phthalates, accounting for over 60% of PVC plastic additives. The removal of DEP from the environment is crucial for human and biological health. DEP mainly binds to plastics through weak van der Waals forces and hydrogen bonds. Research on the binding effect and mechanism of DEP by plastics is limited. This experiment uses DEP in water as the target pollutant to study the rapid removal and recovery effect of PVC plasticization. Therefore, the pollution control and remediation of diethyl phthalate in soil and aquatic environments needs to be given attention. Summary of the Invention

[0004] This invention discloses a method for removing DEP from water using polyvinyl chloride (PVC), aiming to remove DEP-like substances from water in a short time. The method involves introducing synthetic PTFR into DEP-contaminated water, causing it to undergo a plasticizing reaction upon contact with the aqueous phase. This process absorbs the DEP pollutant while simultaneously forming a plastic suspension (solid), thereby separating the DEP from the aqueous phase.

[0005] To achieve the above objectives, the present invention adopts the following technical approach:

[0006] A method for rapidly treating DEP in wastewater utilizes the ultrasonic resonance solubility of PVC and tetrahydrofuran, allowing PVC to be in a metastable state in solution. Upon contact with DEP, PVC rapidly undergoes a plasticizing reaction to form a plastic solid that is easily removed from the water. The solution prepared using this method is called PTFR.

[0007] The specific steps are as follows:

[0008] (1) Four systems of solutions were added to DEP wastewater of different concentrations: PVC, THF solution, PVC and THF mixture solution, and PTFR solution. The experimental phenomena were observed, and the removal efficiency of DEP in the wastewater at the moment of addition to the reaction was determined.

[0009] (2) To determine the appropriate ratio for PTFR, four concentrations of 12.5 mg / L, 25 mg / L, 50 mg / L, and 100 mg / L were selected to represent their respective left and right concentration ranges for the experiment. The experimental phenomena were observed, and the removal efficiency of DEP in the wastewater at the moment of addition to the reaction was measured.

[0010] (3) To determine a better treatment method, experiments were conducted on wastewater with a specific DEP concentration using different treatment methods. The experimental phenomena were observed, and the removal efficiency of DEP in the wastewater at the moment of addition to the reaction was measured.

[0011] (4) To determine the efficiency limit of the treatment, continuous treatment was carried out using the treatment method obtained in (3). The experimental phenomena were observed, and the removal efficiency of DEP in the wastewater at the moment of addition to the reaction was measured.

[0012] (5) In order to achieve sustainable development of resources, the plastics obtained after treatment are separated and purified to recover DEP from the plastics.

[0013] This invention utilizes the plasticizing ability of PVC plastic and its interaction with DEP to develop a cutting-edge technology for the instantaneous removal of DEP from wastewater. The materials used in this technology are hereinafter referred to as PTFR. The steps are as follows: a) Place an appropriate amount of tetrahydrofuran (THF) in a beaker of suitable capacity; the volume of the beaker should not exceed three times the volume of the tetrahydrofuran. b) Add an appropriate amount of PVC to the beaker in a suitable ratio. PTFR synthesis must consider both the donor and acceptor parameters of THF, as well as the Cl-... -The process involves: c) Observing the effect of PTFR as an electron donor and the degree of acceptance of THF as an acceptor; d) Sealing the obtained homogeneous solution and sonicating it in pure water for 10-15 minutes until the solution becomes clear; e) Adding the obtained PTFR to the DEP wastewater, which immediately produces water-insoluble plastics. The plastics are then removed and allowed to evaporate after THF, followed by subsequent recycling treatment. Compared with directly using PVC to remove organic pollutants such as DEP from water bodies, the above scheme greatly increases the removal efficiency, saves pollution treatment time, makes the treated pollutants easier to remove, and allows for the recycling of DEP from the plastics, achieving the goal of generating revenue from waste and reusing resources.

[0014] Compared with the prior art, the advantages of the present invention are:

[0015] It can instantly remove DEP contaminants from water, forming insoluble plastics that are easily separated from the solution. Separation and purification techniques can be used to recover the plastics and DEP from the plastics. This technology improves the efficiency of contaminant removal while using the same PVC material, significantly saving time and costs in pollution treatment. The generated secondary products are beneficial for subsequent resource recycling and reuse. Attached Figure Description

[0016] Figure 1 This is a diagram showing the experimental results of Example 1.

[0017] Figure 2 The diagram shows the effect of PTFR removing DEP wastewater at different concentration ratios. The concentrations in each tank from left to right are 100, 50, 25, 12.5, 6.25, 3.125, and 1.5625 mg / L.

[0018] Figure 3 The images show the effects of using batch and continuous treatment methods to treat DEP wastewater, respectively.

[0019] Figure 4 This is a diagram illustrating the effect of treating DEP wastewater using a continuous treatment method.

[0020] Figure 5 The images show the effects of treating high / low concentration DEP wastewater. The left image shows the effect of treating high concentration DEP wastewater, and the right image shows the effect of treating low concentration DEP wastewater.

[0021] Figure 6 This image shows the effect of adding synthetic PTFR to water.

[0022] Figure 7 This image shows the effect of DEP recycling in the treated plastics.

[0023] Figure 8 This is a mechanism diagram of the present invention.

[0024] Figure 9 This is a mechanism diagram of the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0026] The method in this embodiment is as follows:

[0027] A method for rapidly treating DEP in wastewater includes the following steps:

[0028] (1) PVC and THF solution were fused together and then prepared into PTFR under ultrasonic resonance conditions;

[0029] (2) Add the PTFR obtained in step (1) to the DEP wastewater, stir rapidly, and remove the plasticizer;

[0030] (3) Place the liquid obtained in step (2) in a fume hood and wait for the THF solution to evaporate to complete the pollution treatment process.

[0031] In the above method, in step (1), the PVC is a powder or granular solid with a particle size of 20-80 mesh.

[0032] In the above method, in step (1), the THF is HPLC grade, ≥99.9%.

[0033] In the above method, in step (1), the PTFR fusion method is to add PVC powder to a THF solution that is being stirred at high speed.

[0034] In the above method, the rate at which PVC is added to the THF solution during the fusion process is 100-500 mg / min, the stirring time is 5-10 min, and the ultrasonic resonance time is 5-15 min.

[0035] In the above method, the PTFR concentration is 10-120 mg / L (PVC:THF solution).

[0036] In the above method, in step (2), the volume ratio of the added PTFR to the volume of DEP wastewater is 2%-10%.

[0037] In the above method, step (2) specifically refers to removing the plasticized material within 1 minute.

[0038] In the above method, in step (3), the solution is left to stand for 8-48 hours.

[0039] Example 1

[0040] like Figure 1 The figure shows the treatment effects of adding four different solutions to DEP wastewater. From the figure, the following conclusions can be drawn: a) THF has no effect on DEP removal; b) PVC has an effect on DEP removal, but this effect is weakened after adding THF to the mixed PVC and DEP solution. This is because the addition of THF makes PVC molecules more active, reducing their ability to fix DEP molecules, thus weakening the removal efficiency; c) PTFR has a very high DEP removal efficiency in DEP wastewater, approximately 2.5 times that of PVC alone. This is because PVC is pretreated, and THF interacts with PVC molecules via EDA, selectively breaking the C-Cl / CH bonds in the PVC molecules, giving them more adsorption sites and increasing the adsorption efficiency for DEP (e.g., ...). Figure 8 (As shown).

[0041] Observations from actual reaction systems show that when the PVC-only system treats DEP wastewater, solid pollutants settle at the bottom of the test tube after the removal process; however, when the PTFR system treats DEP wastewater, the pollutants float on the water surface after the removal process (e.g., Figure 5 As shown), it is easier to remove compared to a single PVC system. Figure 5 As shown, the plasticizers formed when treating high-concentration DEP wastewater exhibit stronger aggregation than those formed when treating low-concentration DEP wastewater. This indicates that PTFR can rapidly adsorb DEP in water, forming easily removable suspended solids. THF does not adsorb DEP, but in an aquatic environment where THF and DEP coexist, the adsorption capacity of PVC for DEP weakens. It is well known that the π-π electron-donor-acceptor interaction is a specific non-covalent attraction between π-donor and π-acceptor molecules. In THF, the presence of epoxy groups acts as a π-electron acceptor, while PVC contains Cl atoms that can act as π-electron donors. Therefore, during PVC adsorption, encountering THF molecules reduces its fixation of DEP, weakens the aggregation effect of the plasticizer, and makes DEP easier to desorb back into the solution.

[0042] Example 2

[0043] like Figure 2The figure shows the experimental results of treating DEP wastewater of different concentrations using four different concentration ratios, with concentrations ranging from 12.5 mg / L to 100 mg / L. Concentrations of PTFR less than 12.5 mg / L and greater than 100 mg / L are not considered from an efficacy and synthesis perspective. PTFR synthesis must consider both the donor and acceptor parameters of THF, as well as the role of Cl- as an electron donor and the acceptor capacity of THF. The following conclusions can be drawn from the figure: a) As shown in the figure, the removal efficiency of DEP-contaminated water reaches its lowest value when the PTFR concentration is around 50 mg / L. The removal efficiency differs significantly between high-concentration and low-concentration DEP wastewater, indicating that PTFR stability is poor within this concentration range. b) As shown in the figure, the removal rate of DEP wastewater of different concentrations is generally low when the PTFR concentration range is around 25 mg / L, indicating that the removal capacity of PTFR within this concentration range is weak. c) As shown in the figure, the removal efficiency is average when the PTFR concentration range is 12.5 mg / L, and there is a significant aqueous phase partitioning effect, meaning that the liquid volume of the wastewater removed by PTFR increases considerably. Obviously, in practical applications, the volume of polluted liquid is large, and the volume of PTFR added also increases accordingly, resulting in a larger final volume expansion, which makes actual operation more difficult. Moreover, when using the same mass of PVC to remove DEP pollution, more THF liquid is consumed, leading to increased costs. d. As shown in the figure, the overall removal efficiency is better when the PTFR concentration is 100 mg / L, and the removal effect is best in treating water samples with a lower concentration of DEP pollution close to the actual water body concentration. Furthermore, when using this concentration of PTFR to treat DEP wastewater, the liquid volume remains basically unchanged, and the liquid phase distribution effect is small. In addition, when using the same mass of PVC to treat DEP wastewater, this concentration requires less THF liquid, saving costs and reducing secondary pollution.

[0044] In summary, considering the overall removal rate, optimal removal rate, operational difficulty of synthesis and use, cost, and environmental protection, PTFR with a concentration range of approximately 100 mg / L was selected as the subsequent treatment concentration.

[0045] Example 3

[0046] like Figure 3 The figures show the removal rate curves for removing DEP wastewater of different concentrations using continuous treatment and sequencing batch processing methods, respectively. Continuous treatment is characterized by higher overall removal rate, but it is more difficult, cumbersome, and time-consuming. Sequencing batch processing, on the other hand, is characterized by simpler operation and faster processing. In real-world water treatment, the more suitable treatment method can be selected based on its characteristics.

[0047] Example 4

[0048] like Figure 4 The figure shows the removal effect of DEP wastewater with a concentration of 12.5 mg / L treated by continuous treatment method. As can be seen from the figure, the removal rate gradually increases with the increase of the number of continuous treatments. The DEP removal rate in the wastewater after 20 continuous treatments is as high as 65%. In the early stage of continuous treatment, the removal effect can be well achieved with the increase of the number of treatments. After the number of continuous treatments accumulates to a certain extent, the increase in the removal effect tends to level off with the increase of the number of treatments.

[0049] Example 5

[0050] like Figure 6 As shown, when the synthesized PTFR is added to DEP wastewater, water-insoluble plasticizers are immediately generated. DEP molecules in the solution are plasticized and fixed within the plasticizers. This substance is easily separated from water, facilitating the separation and purification of DEP. For example... Figure 7 As shown, the recovery rate of DEP in plastics increases as the concentration of DEP in the treated wastewater decreases. This also indicates that in actual water treatment, PTFR technology can not only remove DEP from water instantly and efficiently, but also achieve effective resource recovery, thus implementing the sustainable development concept of turning waste into resources.

[0051] It should be understood that the above detailed description of the technical solutions of the present invention with reference to optimized embodiments is illustrative and not restrictive. It should not be considered that the specific implementation of the present invention is limited to this. For those skilled in the art, any modifications to the technical solutions described in the embodiments or equivalent substitutions of some technical features without departing from the concept of the present invention should be considered as falling within the scope of patent protection defined by the claims submitted by the present invention.

[0052] The above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for rapidly treating DEP in wastewater, characterized in that, Includes the following steps: (1) PVC and THF solution are fused together and then prepared into PTFR under ultrasonic resonance conditions; the PTFR fusion method is to add PVC powder to THF solution under high-speed stirring; the concentration of PVC:THF solution in PTFR is 10-120 mg / L; the rate at which PVC is added to THF solution during the fusion process is 100-500 mg / min, the stirring time is 5-10 min, and the ultrasonic resonance time is 5-15 min; (2) Add the PTFR obtained in step (1) to the DEP wastewater, stir rapidly, and remove the plasticizer; (3) Place the liquid obtained in step (2) in a fume hood and wait for the THF solution to evaporate to complete the pollution treatment process.

2. The method for rapidly treating DEP in wastewater according to claim 1, characterized in that, In step (1), the PVC is a powder or granular solid with a particle size of 20-80 mesh.

3. The method for rapidly treating DEP in wastewater according to claim 1, characterized in that, In step (1), the THF is HPLC grade, ≥99.9%.

4. The method for rapidly treating DEP in wastewater according to claim 1, characterized in that, In step (2), the volume ratio of the added PTFR to the volume of DEP wastewater is 2%-10%.

5. The method for rapidly treating DEP in wastewater according to claim 1, characterized in that, In step (2), the removal of the plasticized material specifically means: removing the plasticized material within 1 minute.

6. The method for rapidly treating DEP in wastewater according to claim 1, characterized in that, In step (3), the placement time in the fume hood is 8-48 hours.

7. A PTFR for treating wastewater, prepared by the method according to any one of claims 1-6.

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