A degradable photocatalytic bacterial cellulose film and its preparation method and application

Abstract

The present invention belongs to the technical field of preparing degradable photocatalytic cellulose membranes, specifically relating to a degradable photocatalytic bacterial cellulose membrane, its preparation method, and its application. This invention fully utilizes green solar energy for photocatalytic depolymerization of lignin, achieving efficient and green degradation of lignin to produce high-value products. It can photocatalytically degrade residual organic matter, such as lignin, in pulping and papermaking wastewater, avoiding the high treatment volume and low treatment efficiency associated with direct photocatalytic treatment of pulping and papermaking wastewater. It also addresses the difficulty of regenerating and recycling most photocatalytic materials used in wastewater treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of degradable photocatalytic cellulose films, and in particular relates to a degradable photocatalytic bacterial cellulose film and a preparation method and application thereof. Background Art

[0002] Plants on Earth produce approximately 150 billion tons of the naturally occurring aromatic macromolecule lignin annually through photosynthesis, in addition to a vast amount of cellulose. However, this abundant natural resource remains underutilized, with only a tiny fraction of lignin being developed into chemicals. As a plentiful and renewable biomass energy source, effectively degrading lignin into commonly used chemicals or materials, achieving its high-value conversion, has recently become a research hotspot for scholars both domestically and internationally.

[0003] Solar energy is the most widely used, greenest, and most sustainable energy source on Earth. Photocatalysis is a clean, efficient, energy-saving, environmentally friendly, and low-cost technology that not only utilizes solar energy but also depolymerizes lignin under mild conditions at room temperature and pressure, offering enormous potential for application. In 1989, Kobayakawa et al. first reported the use of TiO2 as a photocatalyst for lignin degradation. Under specific conditions, TiO2 completely decomposes kraft lignin into carbon dioxide and water. Since then, photocatalytic technology for lignin degradation using various materials under illumination has gradually matured. Its environmentally friendly and economical characteristics have led researchers to develop a large number of photocatalysts, including In2S3, Ni-Fe / AC, CuSO4, ZnS, ZnO, POMs, Ag2S, hydrotalcites, and perovskites. However, in reality, these photocatalysts all have their own advantages and disadvantages, either suffering from low photocatalytic efficiency or being restricted by a narrow light response range. Summary of the Invention

[0004] In response to the current problems in lignin degradation and the limitation of the response range of photocatalysts, the present invention provides a degradable photocatalytic bacterial cellulose membrane, which fully utilizes green solar energy for photocatalytic lignin depolymerization, completes the green and efficient degradation of lignin to obtain high-value products; it can realize the photocatalytic degradation of residual organic matter such as lignin in pulping and papermaking wastewater, avoiding the problems of large processing volume and low processing efficiency when directly photocatalytically treating pulping and papermaking wastewater, and solves the problem that most photocatalytic materials are difficult to regenerate and recycle when treating wastewater.

[0005] The technical solutions of the present invention are as follows:

[0006] A degradable photocatalytic bacterial cellulose film comprises the following raw materials in parts by weight: 50-90 parts of bacterial cellulose, 1-60 parts of polyvinylidene fluoride (PVDF), 1-10 parts of N,N-dimethylformamide (DMF), 1-5% of a silane coupling agent, and 0.1-1 part of MOF.

[0007] Preferably, the MOF is UiO-66-NH2(Zr) or UiO-66-NH2(Hf).

[0008] Preferably, the bacterial cellulose has a diameter of 50-100 nm and a length of >20 μm.

[0009] The method for preparing the degradable photocatalytic bacterial cellulose membrane comprises the following steps: mixing the raw materials according to a ratio, ultrasonically dispersing the raw materials, filtering the raw materials, and drying the raw materials.

[0010] Another object of the present invention is to protect the application of the above-mentioned degradable photocatalytic bacterial cellulose film in lignin degradation.

[0011] Another object of the present invention is to protect the application of the above-mentioned degradable photocatalytic bacterial cellulose membrane in the treatment of pulping and papermaking wastewater.

[0012] The mechanism of photocatalysis adopted in this application is:

[0013] The loaded MOF material used in the present invention is used to prepare a degradable photocatalytic bacterial cellulose membrane. On the one hand, it is based on the charge transition and charge transfer of different components derived from MOF, thereby generating electron-hole separation behavior under light excitation; on the other hand, it utilizes the porous structure and surface active sites of MOF to adsorb and catalyze photocatalytic reactants, thereby achieving efficient degradation of pollutants.

[0014] Beneficial effects of the present invention

[0015] 1. The preparation method is simple and only requires ultrasonic filtration to prepare, which is suitable for industrial production.

[0016] 2. The prepared materials are degradable;

[0017] 3. It has remarkable effect in treating pulp and papermaking wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The degradable photocatalytic bacterial cellulose film prepared in Example 5;

[0019] Figure 2 This is a scanning electron micrograph of the degradable photocatalytic bacterial cellulose film prepared in Example 5;

[0020] Figure 3This is a comparison chart of the degradable photocatalytic bacterial cellulose membrane prepared in Example 5 before and after degradation. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to specific examples; unless otherwise specified, the parts in the examples are by mass.

[0022] Example 1

[0023] A method for preparing a degradable photocatalytic bacterial cellulose membrane comprises the following steps: adding 50 parts of bacterial cellulose, 1 part of PVDF, 1 part of DMF, 1 part of silane coupling agent and 0.1 part of UiO-66-NH2(Hf) into an ultrasonic disperser, and ultrasonically dispersing for 10 minutes; transferring the above product into a suction filter and filtering for 10 minutes; placing the wet membrane in a flat plate dryer at 100°C and drying for 5 minutes to obtain a degradable photocatalytic bacterial cellulose membrane based on MOF material.

[0024] The material was placed in 1000 parts of papermaking wastewater with a residual lignin concentration of 50 ppm and irradiated with a 300W sunlight simulation lamp for 1 hour. The lignin degradation rate reached 32.5%.

[0025] Example 2

[0026] A method for preparing a degradable photocatalytic bacterial cellulose membrane comprises the following steps: adding 50 parts of bacterial cellulose, 5 parts of PVDF, 3 parts of DMF, 2 parts of a silane coupling agent and 0.4 parts of UiO-66-NH2(Hf) into an ultrasonic disperser, and ultrasonically dispersing for 10 minutes; transferring the above product into a suction filter and filtering for 10 minutes; and drying the wet membrane in a flat plate dryer at 100°C for 5 minutes to obtain a degradable photocatalytic bacterial cellulose membrane based on MOF material.

[0027] The material was placed in 1000 parts of papermaking wastewater with a residual lignin concentration of 50 ppm and irradiated with a 300W sunlight simulation lamp for 1 hour. The lignin degradation rate reached 74.8%.

[0028] Example 3

[0029] A method for preparing a degradable photocatalytic bacterial cellulose membrane comprises the following steps: adding 50 parts of bacterial cellulose, 5 parts of PVDF, 5 parts of DMF, 2 parts of a silane coupling agent and 0.8 parts of UiO-66-NH2(Hf) into an ultrasonic disperser, and ultrasonically dispersing the mixture for 10 minutes; transferring the mixture into a suction filter and filtering the mixture for 10 minutes; and drying the wet membrane in a flat plate dryer at 100°C for 5 minutes to obtain a degradable photocatalytic bacterial cellulose membrane based on MOF material.

[0030] The material was placed in 1000 parts of papermaking wastewater with a residual lignin concentration of 50 ppm and irradiated with a 300W sunlight simulation lamp for 1 hour. The lignin degradation rate reached 95.7%.

[0031] Example 4

[0032] A method for preparing a degradable photocatalytic bacterial cellulose membrane comprises the following steps: adding 50 parts of bacterial cellulose, 10 parts of PVDF, 5 parts of DMF, 3 parts of a silane coupling agent and 0.8 parts of UiO-66-NH2(Hf) into an ultrasonic disperser, and ultrasonically dispersing for 10 minutes; transferring the above product into a suction filter and filtering for 10 minutes; and drying the wet membrane in a flat plate dryer at 100°C for 8 minutes to obtain a degradable photocatalytic bacterial cellulose membrane based on MOF material.

[0033] The material was placed in 1000 parts of papermaking wastewater with a residual lignin concentration of 50 ppm and irradiated with a 300W sunlight simulation lamp for 1 hour. The lignin degradation rate reached 95.7%.

[0034] Example 5

[0035] A method for preparing a degradable photocatalytic bacterial cellulose membrane comprises the following steps: adding 80 parts of bacterial cellulose, 20 parts of PVDF, 8 parts of DMF, 3 parts of a silane coupling agent and 0.8 parts of UiO-66-NH2(Hf) into an ultrasonic disperser, and ultrasonically dispersing for 10 minutes; transferring the above product into a suction filter and filtering for 10 minutes; and placing the wet membrane in a flat plate dryer at 100°C and drying for 8 minutes to obtain a degradable photocatalytic bacterial cellulose membrane based on MOF material.

[0036] The material was placed in 1000 parts of papermaking wastewater with a residual lignin concentration of 50 ppm and irradiated with a 300W sunlight simulation lamp for 1 hour. The lignin degradation rate reached 98.1%.

[0037] Example 6

[0038] A method for preparing a degradable photocatalytic bacterial cellulose membrane comprises the following steps: adding 80 parts of bacterial cellulose, 20 parts of PVDF, 8 parts of DMF, 3 parts of a silane coupling agent and 0.8 parts of UiO-66-NH2(Zr) into an ultrasonic disperser, and ultrasonically dispersing for 10 minutes; transferring the above product into a suction filter and filtering for 10 minutes; and drying the wet membrane in a flat plate dryer at 100°C for 8 minutes to obtain a degradable photocatalytic bacterial cellulose membrane based on MOF material.

[0039] The material was placed in 1000 parts of papermaking wastewater with a residual lignin concentration of 50 ppm and irradiated with a 300W sunlight simulation lamp for 1 hour. The lignin degradation rate reached 92.5%.

[0040] Example 7

[0041] A method for preparing a degradable photocatalytic bacterial cellulose membrane comprises the following steps: adding 80 parts of bacterial cellulose, 30 parts of PVDF, 8 parts of DMF, 5 parts of a silane coupling agent, and 0.8 parts of UiO-66-NH2(Hf) into an ultrasonic disperser, and ultrasonically dispersing the mixture for 10 minutes; transferring the mixture into a suction filter, and filtering the mixture for 10 minutes; and drying the wet membrane in a flat plate dryer at 100°C for 10 minutes to obtain a degradable photocatalytic bacterial cellulose membrane based on MOF material.

[0042] The material was placed in 1000 parts of papermaking wastewater with a residual lignin concentration of 50 ppm and irradiated with a 300W sunlight simulation lamp for 1 hour. The lignin degradation rate reached 97.8%.

[0043] Comparative Example 1 Compared with Example 5, it does not contain MOF

[0044] A method for preparing a degradable photocatalytic bacterial cellulose membrane based on MOF material comprises the following steps: adding 80 parts of bacterial cellulose, 20 parts of PVDF, 8 parts of DMF and 3 parts of silane coupling into an ultrasonic disperser, and ultrasonically dispersing for 10 minutes; transferring the above product into a suction filter and filtering for 10 minutes; placing the wet membrane in a flat plate dryer at 100°C and drying for 8 minutes to obtain a degradable photocatalytic bacterial cellulose membrane based on MOF material.

[0045] The material was placed in 1000 parts of papermaking wastewater with a residual lignin concentration of 50 ppm and irradiated with a 300W sunlight simulation lamp for 1 hour, but no lignin degradation was observed.

[0046] Comparative Example 2 does not contain bacterial cellulose compared to Example 5

[0047] A method for preparing a degradable photocatalytic bacterial cellulose membrane based on MOF material comprises the following steps: adding 20 parts of PVDF, 8 parts of DMF and 3 parts of silane coupling into an ultrasonic disperser, and ultrasonically dispersing for 10 minutes; transferring the above product into a suction filter and filtering for 10 minutes, but no membrane material can be obtained.

[0048] Comparative Example 3 does not contain PVDF compared to Example 5

[0049] A method for preparing a degradable photocatalytic bacterial cellulose membrane based on MOF material comprises the following steps: adding 80 parts of bacterial cellulose, 8 parts of DMF and 3 parts of silane coupling into an ultrasonic disperser, and ultrasonically dispersing for 10 minutes; transferring the above product into a suction filter and filtering for 10 minutes; placing the wet membrane in a flat plate dryer at 100°C and drying for 8 minutes to obtain a degradable photocatalytic bacterial cellulose membrane based on MOF material.

[0050] The material was placed in 1000 parts of papermaking wastewater with a residual lignin concentration of 50 ppm and irradiated with a 300W sunlight simulation lamp for 1 hour. The bacterial cellulose membrane decomposed and broke and could not be reused.

[0051] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A degradable photocatalytic bacterial cellulose film for lignin degradation, comprising the following raw materials in parts by weight: 50-90 parts bacterial cellulose, 1-60 parts polyvinylidene fluoride, 1-10 parts N,N-dimethylformamide, 1-5 parts silane coupling agent, and 0.1-1 part MOF; the MOF is UiO-66-NH2-Zr or UiO-66-NH2-Hf; The preparation of the degradable photocatalytic bacterial cellulose membrane comprises the following steps: mixing raw materials according to a ratio, ultrasonically dispersing, filtering, and drying.

2. The use according to claim 1, characterized in that The bacterial cellulose has a diameter of 50-100 nm and a length of >20 μm.

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