A starch-based composite film preparation method and its heavy metal detection application

Abstract

The application discloses a starch-based composite film preparation method and heavy metal detection application thereof, and the preparation method comprises the following steps: (1) starch (HPS) is heated and stirred for a certain time to prepare a gelatinized solution; (2) calcium disodium ethylenediaminetetraacetate (EDTA-Ca) and polyvinyl alcohol (PVA) are added to the gelatinized solution and stirred until a film-forming solution is completely defoamed and dried. Before testing, the prepared composite film is measured at room temperature to obtain a portable starch-based composite film. The starch-based composite film is prepared by controlling the starch dosage, reaction temperature, stirring speed and EDTA-Ca dosage. The starch-based composite film obtained by the application exhibits excellent detection performance in heavy metal detection application.

Description

Technical Field

[0001] This invention belongs to the field of biocomposite membranes, and specifically relates to a CNF / PVA-based composite membrane, its preparation method and applications, belonging to the field of thin films. Background Technology

[0002] Heavy metal pollution has been a persistent and difficult problem in the process of industrialization. It not only causes irreversible damage to ecosystems but also leads to a series of issues such as malformation and stunted growth in plants and animals. Long-term exposure to heavy metals can damage cell structures (cell membranes, lysosomes, cell nuclei, and enzymes involved in metabolism, detoxification, and repair), threaten internal organs, cause reproductive disorders, affect growth and development, and even trigger cancer. The density of heavy metal ions (HMI) is typically around 4.5 g / cm³. 3 The above commonly include copper ions (Cu). 2+ ), lead ions (Pb) 2+ Nickel ions (Ni) 2+ ), mercury ions (Hg) 2+ HMI (Hydrogen Microspheres) plasma is characterized by high toxicity, reluctance to degrade, wide availability, and difficulty in treatment. It is found not only in industrial wastewater and discarded batteries, but also in traditional Chinese medicine and seafood products. Therefore, the detection of HMI is a research area of ​​great significance.

[0003] Currently, the main analytical methods for HMI detection include atomic absorption spectrometry, electrochemical methods, inductively coupled plasma mass spectrometry, and surface-enhanced Raman scattering. These methods all suffer from drawbacks such as expensive equipment, complex operation, limitations in the detection environment, and high requirements for specialized expertise. The colorimetric method employed in this invention is convenient, fast, requires less specialized expertise, is low-cost, and has a wide range of applications, thus overcoming some of the aforementioned problems. In recent years, through continuous exploration, green and low-cost detection materials have been widely developed, including chitosan, sodium alginate, cellulose, and polylactic acid. Here, by utilizing the synergistic effect of biomaterials and heavy metal complexing agents, the detection of HMI has been achieved, and a biomass material with a high detection limit and wide sensitivity has been prepared. Summary of the Invention

[0004] The main objective of this invention is to provide a method for preparing starch-based composite membranes and their application in heavy metal detection. This invention provides some assistance for future applications in the detection of HMI content in traditional Chinese medicine materials and seafood, expands the application potential of biomass materials, and provides some reference for the design of similar functional materials.

[0005] This invention includes the following steps: (1) Preparation of starch gelatinization solution Add HPS to distilled water and stir for a period of time to make a gelatinized solution. After the gelatinization is complete, store it at high temperature for later use. (2) Preparation of starch-based composite film Disodium calcium ethylenediaminetetraacetate (EDTA-Ca) and polyvinyl alcohol (PVA) were added to a gelatinization solution and stirred until the film-forming solution was completely defoamed. The composite solution was then cast onto a petri dish and dried in a forced-air drying oven at 35°C to prepare a composite film. Before testing, the prepared composite film was pressed into a special mold and stored at room temperature for 48 hours before measurement.

[0006] In step (1), the starch is one or more of potato starch, corn starch, pea starch, purple sweet potato starch, and rice starch, and its mass is 2 to 20 g.

[0007] In step (1), the gelatinization temperature during the heating process is 60-120℃, the heating rate is 0.1-10 K / min, the stirring rate is 100-800 rpm, and the gelatinization time is 10-300 min.

[0008] In step (2), the mass of EDTA-Ca is 0.2–20 g, the mass of PVA is 2–20 g, and the solid content is 5–90%.

[0009] In step (2), the reaction temperature is 60-200℃, the heating rate is 1-10 K / min, the stirring rate is 100-800 rpm, and the reaction time is 10-500 min.

[0010] This invention provides a starch-based composite film, prepared according to the method described above.

[0011] This invention also provides the application of the above-mentioned starch-based composite film in heavy metal detection. Specifically, CuSO4 is accurately dissolved in distilled water to prepare 0.5–5 g / L of the film. -1 The starch-based composite membrane was prepared by diluting solutions to achieve concentrations of 1–1000 ppm. Subsequently, the membrane was vertically immersed in CuSO4 solutions of 50–2000 ppm (removed after 2–20 seconds), and the obvious color changes were visually observed and recorded. The absorbance of the starch-based composite membrane was measured using UV-Vis light, and the most effective HMI detection group was selected by averaging (repeated 3–5 times per group). The selected composite membrane was then vertically immersed in HMI solutions of different ppm concentrations for 2–20 seconds, and excess moisture was blotted with filter paper. Images were captured using a mobile phone camera, and the corresponding R, G, and B values ​​were analyzed using computer software (color recognition device) to prepare a colorimetric chart.

[0012] The beneficial effects of this invention are reflected in the following: (1) The starch-based composite film for portable HMI detection prepared by this invention is obtained from biodegradable material HPS. The synergistic effect of HPS and EDTA-Ca on HMI enables the composite film to have high sensitivity, achieving detection of Cu...2+ The sensitive detection provides a new approach for the detection of heavy metal ions in traditional Chinese medicine and seafood.

[0013] (2) In the preparation of composite films, the present invention does not require high-energy-consuming processing methods, the process is simple and easy to industrialize.

[0014] (3) The present invention utilizes the complexation effect between HPS and EDTA-Ca to make the matrix more tightly connected, without chemical cross-linking, and has good thermodynamic properties and low cost.

[0015] (4) PVA is added to this invention. Its addition as a toughening agent helps to compensate for the shortcomings of insufficient strength and toughness of HPS as a substrate.

[0016] (5) The present invention incorporates the traditional detoxifying drug EDTA-Ca, which expands its future application in the market. Attached Figure Description

[0017] Figure 1 The image shows a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM) image of a starch-based composite film, corresponding to Example 1. Figure 2 This is a flowchart of the preparation process of starch-based composite films, corresponding to Example 2; Figure 3 The image shows the scanning electron microscope results of the starch-based composite film, corresponding to Example 3; Figure 4 The image shows the X-ray diffraction pattern of the starch-based composite film, corresponding to Example 4. Figure 5 The graph shows a comparison of the moisture absorption rates of starch-based composite films, corresponding to Example 5. Figure 6 The thermogravimetric analysis diagram of the starch-based composite film corresponds to Example 6; Figure 7 Scanning electron microscope-energy dispersive X-ray spectroscopy image of starch-based composite film after immersion in CuSO4 solution, corresponding to Example 7; Detailed Implementation

[0018] The present invention will be further described below with reference to embodiments: Unless otherwise specified, all raw materials and equipment used in the following embodiments are commercially available products known in the art. Example

[0019] A method for preparing a starch / polyvinyl alcohol composite film includes the following steps: (1) Preparation of starch gelatinization solution Take 10 g of HPS and add it to 50 mL of distilled water. Stir at 150 rpm and react for 2 h to prepare a gelatinized solution. After the reaction is complete, store it at high temperature for later use. (2) Preparation of starch-based composite film 10 g of polyvinyl alcohol (PVA) was added to the gelatinization solution and stirred at 500 rad / min for 2 h, then at 200 rpm for 6 h until the film-forming solution was completely defoamed. The solution was then cast onto a petri dish and dried in a forced-air drying oven at 35°C for 10 h. The experiment was then completed, and the sample was labeled SCP.

[0020] like Figure 1 The image shows a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM) image of a starch-based composite film. Example

[0021] A method for preparing a starch / polyvinyl alcohol / disodium calcium ethylenediaminetetraacetate composite film includes the following steps: (1) Preparation of starch gelatinization solution Take 10 g of HPS and add it to 50 mL of distilled water. Stir at 150 rpm and react for 2 h to prepare a gelatinized solution. After the reaction is complete, store it at high temperature for later use. (2) Preparation of starch-based composite film 10 g of PVA and 2% wt of EDTA-Ca were added to the gelatinization solution and stirred at 500 rad / min for 2 h and 200 rpm for 6 h until the film-forming solution was completely defoamed. The solution was then cast onto a petri dish and dried in a forced-air drying oven at 35°C for 10 h. The experiment was then completed, and the sample was labeled SCPE-1.

[0022] like Figure 2 The preparation process of starch-based composite films is demonstrated. Example

[0023] A method for preparing a starch / polyvinyl alcohol / disodium calcium ethylenediaminetetraacetate composite film includes the following steps: (1) Preparation of starch gelatinization solution Take 10 g of HPS and add it to 50 mL of distilled water. Stir at 150 rpm and react for 2 h to prepare a gelatinized solution. After the reaction is complete, store it at high temperature for later use. (2) Preparation of starch-based composite film 10 g of PVA and 4% wt of EDTA-Ca were added to the gelatinization solution and stirred at 500 rad / min for 2 h and 200 rpm for 6 h until the film-forming solution was completely defoamed. The solution was then cast onto a petri dish and dried at 35°C in a forced-air drying oven for 10 h. The experiment was then completed, and the sample was labeled SCPE-2.

[0024] like Figure 3 The image shows the scanning electron microscope results of the starch-based composite film. Example

[0025] A method for preparing a starch / polyvinyl alcohol / disodium calcium ethylenediaminetetraacetate composite film includes the following steps: (1) Preparation of starch gelatinization solution Take 10 g of HPS and add it to 50 mL of distilled water. Stir at 150 rpm and react for 2 h to prepare a gelatinized solution. After the reaction is complete, store it at high temperature for later use. (2) Preparation of starch-based composite film 10 g of PVA and 6% wt of EDTA-Ca were added to the gelatinization solution and stirred at 500 rad / min for 2 h and 200 rpm for 6 h until the film-forming solution was completely defoamed. The solution was then cast onto a petri dish and dried at 35°C in a forced-air drying oven for 10 h. The experiment was then completed, and the sample was labeled SCPE-3.

[0026] like Figure 4 The X-ray diffraction pattern of the powder-based composite film is shown. Example

[0027] A method for preparing a starch / polyvinyl alcohol / disodium calcium ethylenediaminetetraacetate composite film includes the following steps: (1) Preparation of starch gelatinization solution Take 10 g of HPS and add it to 50 mL of distilled water. Stir at 150 rpm and react for 2 h to prepare a gelatinized solution. After the reaction is complete, store it at high temperature for later use. (2) Preparation of starch-based composite film 10 g of PVA and 8% wt of EDTA-Ca were added to the gelatinization solution and stirred at 500 rad / min for 2 h and 200 rpm for 6 h until the film-forming solution was completely defoamed. The solution was then cast onto a petri dish and dried at 35°C in a forced-air drying oven for 10 h. The experiment was then completed, and the sample was labeled SCPE-4.

[0028] like Figure 5 A comparison chart of the moisture absorption rates of starch-based composite films is shown. Example

[0029] A method for preparing a starch / polyvinyl alcohol / disodium calcium ethylenediaminetetraacetate composite film includes the following steps: (1) Preparation of starch gelatinization solution Take 10 g of HPS and add it to 50 mL of distilled water. Stir at 150 rpm and react for 2 h to prepare a gelatinized solution. After the reaction is complete, store it at high temperature for later use. (2) Preparation of starch-based composite film 10 g of PVA and 10%wt of EDTA-Ca were added to the gelatinization solution and stirred at 500 rad / min for 2 h and 200 rpm for 6 h until the film-forming solution was completely defoamed. The solution was then cast onto a petri dish and dried in a forced-air drying oven at 35°C for 10 h. The experiment was then completed, and the sample was labeled SCPE-5.

[0030] like Figure 6 The thermogravimetric analysis results of the starch-based composite film are shown. Example

[0031] A method for heavy metal detection in starch / polyvinyl alcohol / disodium calcium ethylenediaminetetraacetate composite films includes the following steps: CuSO4 was accurately dissolved in distilled water to prepare a solution of 2.0 g / L. -1 The solution was diluted sequentially to prepare ionic solutions ranging from 1 to 2000 ppm. The SCPE film was vertically immersed in CuSO4 solutions of different ppm concentrations for 5 seconds, and excess water was blotted dry with filter paper. Images were captured using a mobile phone camera, and the corresponding R, G, and B values ​​were analyzed using computer software (color recognition device) to prepare a colorimetric chart.

[0032] like Figure 7 The image shows a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM) image of a starch-based composite film after it has been immersed in CuSO4 solution.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a starch-based composite film, characterized in that, Includes the following steps: (1) Preparation of starch (HPS) gelatinized solution HPS was subjected to a gelatinization reaction to prepare a gelatinized solution, which was then stored at high temperature for later use. (2) Preparation of starch-based composite film Add calcium disodium ethylenediaminetetraacetate (EDTA-Ca) and polyvinyl alcohol (PVA) to the gelatinization solution and stir until the film-forming solution is completely defoamed and dried.

2. The method for preparing the starch-based composite film as described in claim 1, characterized in that, In step (1), the starch is one or more of potato starch, corn starch, pea starch, purple sweet potato starch, and rice starch, and its mass is 2 to 20 g.

3. The method for preparing the starch-based composite film as described in claim 1, characterized in that, In step (1), the gelatinization temperature during the heating process is 60-120℃, the heating rate is 0.1-10 K / min, the stirring rate is 100-800 rpm, and the gelatinization time is 10-300 min.

4. The method for preparing the starch-based composite film as described in claim 1, characterized in that, In step (2), the mass of EDTA-Ca is 0.2–20 g, the mass of PVA is 2–20 g, and the solid content is 5–90%.

5. The method for preparing the starch-based composite film as described in claim 1, characterized in that, In step (2), the reaction temperature is 60-200℃, the heating rate is 1-10 K / min, the stirring rate is 100-800 rpm, and the reaction time is 10-500 min.

6. A starch-based composite film, characterized in that, Prepared according to the method of any one of claims 1 to 5.

7. The application of the starch-based composite membrane as described in claim 6 in the detection of heavy metals.

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