A method for deinking mixed office waste paper using TENG electrical treatment

Abstract

This invention provides a method for deinking mixed office waste paper using a triboelectric nanogenerator (TENG) using a PANI-modified cellulose / PDMS composite as the negative electrode friction material. This device generates electricity through friction and is used to deink mixed office waste paper pulp. Compared to deinked pulp without electrolytic treatment, the electrolytically treated MOW pulp achieved optimal results at a TENG tribovoltage of 60V, a stirring speed of 400 rpm, and an electrolytic treatment time of 10 minutes. The results showed an increase in whiteness of 1.5% ISO and a reduction in ERIC of 7.2 mg / kg.

Description

Technical Field

[0001] The present invention relates to the field of clean pulping and papermaking, and in particular to a method for electrically treating mixed office waste (MOW) deinking by generating triboelectricity using a triboelectric nanogenerator (TENG) prepared from a PANI-modified cellulose / PDMS composite material. Background Art

[0002] Waste paper recycling is an important source of raw materials for the papermaking industry. The proportion of recyclable office waste paper is increasing. Mixed office waste (MOW) is a major source of high-quality recycled fiber raw material due to its advantages such as good fiber strength, high whiteness, and low price. However, difficult-to-remove ink impurities affect the clean production and high-quality application of MOW recycled fiber. Traditional chemical deinking methods damage the fibers and produce hazardous wastewater. Exploring low-chemical waste paper deinking methods can effectively reduce energy consumption and environmental pollution. Triboelectric nanogenerators (TENGs), as an emerging energy harvesting technology, offer advantages such as low cost, high conversion efficiency, and a wide range of applications. Cellulose, a natural, abundant and biodegradable polymer, has limited triboelectric output capacity in TENGs. Therefore, exploring the preparation of high-performance cellulose-based triboelectric materials for mixed office waste paper deinking electroprocessing has promising application prospects. Summary of the Invention

[0003] The present invention aims to provide a method for deinking mixed office waste (MOW) by using a triboelectric nanogenerator (TENG).

[0004] The technical solutions of the present invention are as follows:

[0005] A TENG (Telephotovoltaic Generator) electrochemical deinking method for mixed office waste paper is proposed. A triboelectric nanogenerator (TENG) is fabricated using a PANI-modified cellulose / PDMS composite material as the negative electrode friction material. The triboelectric nanogenerator generates electricity through friction and is used for electrochemical deinking of mixed office waste paper pulp.

[0006] The preparation of the PANI-modified cellulose / PDMS composite material includes: using aniline as a monomer, cellulose as a stabilizer, HCl solution as a dopant, and ammonium persulfate as an initiator, and adopting a chemical oxidative polymerization method to prepare polyaniline-modified cellulose in an ice bath; stirring the dried polyaniline-modified cellulose, and then dispersing it in a polydimethylsiloxane stock solution under ultrasonic conditions; then adding a curing agent, stirring thoroughly, and placing it in a vacuum environment to remove bubbles; pouring the mixed liquid into a film-shaped mold, and then curing the polydimethylsiloxane to obtain the PANI-modified cellulose / PDMS composite material.

[0007] Furthermore, the present invention makes a PANI-modified cellulose / PDMS composite material into a film material, attaches a conductive tape to the back of the film material as a negative electrode friction material, and uses paper with a conductive tape attached to the back as a positive electrode friction material to make a friction nanogenerator. The friction nanogenerator generates electricity through contact separation, and then converts the alternating current into direct current through a rectifier bridge. The direct current is then introduced into mixed office waste paper pulp through electrodes for electrical treatment under stirring conditions.

[0008] Furthermore, the mass concentration of the mixed office waste pulp is 1%.

[0009] Furthermore, the process conditions of the electrical treatment are: TENG friction voltage is 30-120 V, stirring speed is 300-600 r / min, and electrical treatment time is 5-20 min.

[0010] Furthermore, it also includes flotation deinking after electrical treatment, and the process conditions of the flotation deinking are: the deinking agent is OP-10, the addition amount is 0.06%, pH=7, temperature is 50°C, flotation concentration is 1%, and flotation time is 10 minutes.

[0011] Furthermore, the mass ratio of the aniline, cellulose and ammonium persulfate is 1:1:1.25.

[0012] Furthermore, the curing agent is tetraethyl orthosilicate.

[0013] Furthermore, the mass ratio of the polyaniline-modified cellulose to the polydimethylsiloxane stock solution is 0.05:1; the mass ratio of the polydimethylsiloxane stock solution to ethyl orthosilicate is 10:1.

[0014] Furthermore, the curing is carried out in an oven at 70°C; and the molding process is carried out in an oven at 70°C.

[0015] The present invention has the following beneficial effects:

[0016] (1) This invention fills polyaniline-modified cellulose (PANI-modified cellulose) inside polydimethylsiloxane (PDMS). During the triboelectric generation process of PDMS, the PANI-modified cellulose becomes a path for electron flow, increasing the density of surface charge and thus enhancing the electrical output performance of the TENG. This friction material has a simple process, low cost, and can generate high electrical output.

[0017] (2) Beneficial results compared to deinked pulp without electrical pretreatment:

[0018] After electro-treatment, the MOW pulp reached the optimal value when the TENG friction voltage was 60 V, the stirring speed was 400 r / min, and the electro-treatment time was 10 min. The whiteness increased by 1.5% ISO and the ERIC decreased by 7.2 mg / kg. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structure of the TENG of the present invention.

[0020] Figure 2 This is a schematic diagram of the TENG electrical treatment device for mixed office waste pulp of the present invention.

[0021] Explanation of the marks in the figure: 1-negative electrode friction material, 2-positive electrode friction material, 3-acrylic plate, 4-conducting wire, 5-electrostat, 6-rectifier bridge, 7-deinking tank, 8-MOW waste paper pulp, 9-stirring device. DETAILED DESCRIPTION

[0022] The present invention is described in further detail below with reference to the embodiments.

[0023] like Figure 1 As shown, the present invention fabricates a PANI-modified cellulose / PDMS composite into a membrane. Conductive tape is applied to the back of the membrane as the negative friction material and adhered to an acrylic plate. A paper with conductive tape applied to the back of the membrane serves as the positive friction material and is also adhered to the acrylic plate to create a TENG device. Wires are connected to the positive electrode of an electrometer, while the negative electrode of the electrometer is grounded, forming a single-electrode TENG. The electrometer is used to measure the TENG's electrical output, and pressure is then varied to control its performance. This is then used for deinking waste paper pulp using electrochemical treatment.

[0024] like Figure 2 As shown, the negative and positive friction materials of the TENG are connected via wires to a rectifier bridge, which is then connected to a deinking tank with electrodes attached. The positive electrode is at the bottom of the tank, and the negative electrode is at the top, with a stirring device in the middle. The negative and positive friction materials of the TENG generate electricity through contact and separation. The rectifier bridge converts the AC power into DC power, which is then passed through the electrodes into mixed office waste pulp (MOW waste pulp) for electrical treatment under stirring conditions.

[0025] Example 1

[0026] A method for deinking mixed office waste paper using TENG electrical treatment, comprising the following steps:

[0027] 1. Preparation of TENG

[0028] (1) Preparation of PANI-modified cellulose / PDMS composite material: Polyaniline-modified cellulose (PANI-modified cellulose) was prepared by chemical oxidation polymerization in an ice bath using 1 g aniline as monomer, 1 g wood cellulose as stabilizer, 100 mL 1 mol / L HCl solution as dopant, and 1.25 g ammonium persulfate as initiator. The dried PANI-modified cellulose was stirred and dispersed in polydimethylsiloxane stock solution (PDMS stock solution) under ultrasonic conditions for 0.5 h. The mass ratio of PANI-modified cellulose to PDMS stock solution was 0.05:1. Then, tetraethyl orthosilicate (TEOS) curing agent was added. The mass ratio of PDMS stock solution to TEOS in the reaction system was 10:1. After thorough stirring, the mixture was placed in a vacuum environment to remove bubbles. The mixed liquid was poured into a film-shaped mold and the PDMS was cured in an oven at 70°C to obtain a PANI-modified cellulose / PDMS composite material.

[0029] (2) A PANI-modified cellulose / PDMS composite material is made into a membrane material. A conductive tape is attached to the back of the membrane material as a negative friction material and adhered to an acrylic plate. A paper with a conductive tape attached to the back is used as a positive friction material and adhered to an acrylic plate. The negative friction material and the positive friction material are connected to a rectifier bridge through wires and then connected to a deinking tank with electrodes attached. The positive electrode is at the bottom of the deinking tank, the negative electrode is at the top of the deinking tank, and a stirring device is in the middle. The negative friction material and the positive friction material of the TENG generate electricity through contact separation, and then the AC power is converted into DC power through the rectifier bridge. The DC power is then passed through the electrodes into mixed office waste pulp (MOW waste pulp) for electrical treatment under stirring conditions.

[0030] 2. Preparation of MOW waste paper pulp:

[0031] MOW waste paper (laser printing paper: inkjet copy paper = 1:1) was torn into 2×2 cm pieces and soaked. The pulp was dispersed using a deflaker and diluted to a pulp suspension with a pulp concentration of 1%.

[0032] 3. The process conditions of electrical treatment are as follows:

[0033] 10g of the bone-dry MOW waste paper pulp from step 2 was prepared into an electrolytic treatment environment with a 1% consistency. The agitator speed was controlled at 400 rpm and the treatment time was 10 minutes. The electrolytic treatment was then performed on the 1% consistency pulp after deflaking. The pulps treated under different treatment conditions were then subjected to flotation deinking and washing using an OP-10.

[0034] 4. The process conditions for flotation deinking after electrical treatment are as follows:

[0035] The pulps subjected to the electrical treatment in step 3 were subjected to flotation deinking. The flotation deinking conditions were as follows: OP-10, a deinking agent at a dosage (mass ratio of deinking agent to absolute dry MOW waste pulp) of 0.06%, a pH of 7, a temperature of 50°C, a flotation concentration (mass concentration of pulp during flotation) of 1%, and a flotation time of 10 minutes. The flotation pulp was then rinsed with tap water using a 60-mesh pulp bag.

[0036] 5. Output performance test:

[0037] The TENG electro-deinked MOW waste paper pulp using tribovoltages of 0V, 30V, 60V, 90V, and 120V. At 0V, the pulp achieved a whiteness of 62.74% ISO and an ERIC of 32.9mg / kg after flotation deinking. At 30V, the pulp achieved a whiteness of 63.3% ISO and an ERIC of 27.3mg / kg. At 60V, the pulp achieved a whiteness of 64.24% ISO and an ERIC of 25.7mg / kg. At 90V, the pulp achieved a whiteness of 64.01% ISO and an ERIC of 28.48mg / kg. At 120V, the pulp achieved a whiteness of 63.9% ISO and an ERIC of 32.85mg / kg.

[0038] Test results: In the TENG electrical treatment system of MOW waste paper pulp, the brightness first increases and then decreases with the increase of voltage, while the ERIC first decreases and then increases with the increase of voltage. When the TENG output voltage is 60V, the brightness of the electrically treated pulp after flotation deinking is 64.24% ISO, and the ERIC is 25.7mg / kg.

[0039] Example 2

[0040] A method for deinking mixed office waste paper using TENG electrical treatment, comprising the following steps:

[0041] 1. Same as step 1 in Example 1.

[0042] 2. Same as step 2 in Example 1.

[0043] 3. The process conditions of electrical treatment are as follows:

[0044] 10g of the bone-dry MOW waste paper pulp from step 2 was prepared into an electrolytic treatment environment with a 1% consistency. The electrolytic treatment was performed on the fluffernated 1% consistency pulp at a controlled friction voltage of 60V and a treatment time of 10 minutes. The pulps treated under different treatment conditions were then subjected to flotation deinking and washing using an OP-10.

[0045] 4. Same as step 4 in Example 1.

[0046] 5. Output performance test:

[0047] TENG performed electro-deinking on MOW waste paper pulp using stirring speeds of 200 r / min, 300 r / min, 400 r / min, 500 r / min, and 600 r / min. At 200r / min, the brightness of the electrically treated pulp after flotation deinking was 62.68%ISO, and the ERIC was 34.28mg / kg; at 300r / min, the brightness of the electrically treated pulp after flotation deinking was 63.65%ISO, and the ERIC was 29.21mg / kg; at 400r / min, the brightness of the electrically treated pulp after flotation deinking was 64.24%ISO, and the ERIC was 25.7mg / kg; at 500r / min, the brightness of the electrically treated pulp after flotation deinking was 63.92%ISO, and the ERIC was 26.69mg / kg; at 600r / min, the brightness of the electrically treated pulp after flotation deinking was 63.73%ISO, and the ERIC was 29.71mg / kg.

[0048] Test results: In the TENG electrical treatment system of MOW waste paper pulp, the brightness first increases and then decreases with the increase of stirring speed, while the ERIC first decreases and then increases with the increase of stirring speed. When the electrical treatment speed is 400r / min, the brightness of the electrically treated pulp after flotation deinking is 64.24%ISO, and the ERIC is 25.7mg / kg.

[0049] Example 3

[0050] A method for deinking mixed office waste paper using TENG electrical treatment, comprising the following steps:

[0051] 1. Same as step 1 in Example 1.

[0052] 2. Same as step 2 in Example 1.

[0053] 3. The process conditions of electrical treatment are as follows:

[0054] 10g of the bone-dry MOW waste paper pulp from step 2 was prepared into an electrolytic treatment environment with a 1% consistency. The voltage was controlled at 60V and the rotation speed was 400r / min. The electrolytic treatment was performed on the 1% consistency pulp after deflaking. The pulps treated under different conditions were then flotated and washed using OP-10.

[0055] 4. Same as step 4 in Example 1.

[0056] 5. Output performance test:

[0057] TENG electro-deinked MOW waste paper pulp at treatment times of 0, 5, 10, 15, and 20 minutes. At 0 minutes, the pulp achieved a whiteness of 62.74% ISO and an ERIC of 32.9 mg / kg after flotation deinking. At 5 minutes, the pulp achieved a whiteness of 63.6% ISO and an ERIC of 30.09 mg / kg. At 10 minutes, the pulp achieved a whiteness of 64.24% ISO and an ERIC of 25.7 mg / kg. At 15 minutes, the pulp achieved a whiteness of 63.32% ISO and an ERIC of 31.86 mg / kg. At 20 minutes, the pulp achieved a whiteness of 63.2% ISO and an ERIC of 32.28 mg / kg.

[0058] Test results: In the TENG electrical treatment system of MOW waste paper pulp, the brightness first increased and then decreased with the increase of electrical treatment time, while the ERIC first decreased and then increased with the increase of electrical treatment time. When the electrical treatment time was 10 minutes, the brightness of the electrically treated pulp after flotation deinking was 64.24% ISO, and the ERIC was 25.7 mg / kg.

[0059] Example 4

[0060] A method for deinking mixed office waste paper using TENG electrical treatment, comprising the following steps:

[0061] 1. Same as step 1 in Example 1.

[0062] 2. Same as step 2 in Example 1.

[0063] 3. Same as step 3 in Example 1.

[0064] 4. Same as step 4 in Example 1.

[0065] 5. Testing of basic properties of pulp suspension and papermaking white water:

[0066] The properties of the pulp suspension and papermaking white water before and after electrotreatment at a voltage of 60 V, a stirring speed of 400 r / min, and an electrotreatment time of 10 min were measured using a conductivity meter, a turbidity meter, a Zeta potential, and a nanoparticle size analyzer. The Zeta potential of the MOW pulp suspension before and after electrotreatment was -7.16 mV and -6.11 mV, the conductivity was 107.9 μS / cm and 127.7 μS / cm, the particle size (D10) was 12.88 μm and 13.84 μm, and the turbidity was 457 NTU and 707 NTU, respectively. The Zeta potential of the papermaking white water before and after electrotreatment was -6.25 mV and -6.84 mV, the conductivity was 116.1 μS / cm and 120.4 μS / cm, the particle size (D10) was 1625 nm and 1851 nm, and the turbidity was 383 NTU and 790 NTU, respectively.

[0067] Test results: The conductivity, turbidity and particle size of the pulp suspension increased to varying degrees, while the Zeta potential, conductivity, turbidity and particle size of the pulp white water increased to varying degrees.

Claims

1. A method for deinking mixed office waste paper using TENG electrical treatment, characterized by: A triboelectric nanogenerator was fabricated using a PANI-modified cellulose / PDMS composite as the negative electrode friction material. This triboelectric nanogenerator generates electricity through friction and is used for the deinking of mixed office waste paper pulp using electrochemical treatment. The preparation of the PANI-modified cellulose / PDMS composite material includes: using aniline as a monomer, cellulose as a stabilizer, HCl solution as a dopant, and ammonium persulfate as an initiator, and adopting a chemical oxidative polymerization method in an ice bath to prepare polyaniline-modified cellulose; The dried polyaniline-modified cellulose was stirred and dispersed in a polydimethylsiloxane stock solution under ultrasonic conditions. A curing agent was then added, and after thorough stirring, the mixture was placed in a vacuum environment to remove bubbles. The mixed liquid was poured into a film-shaped mold and the polydimethylsiloxane was cured to obtain a PANI-modified cellulose / PDMS composite material. The curing agent is tetraethyl orthosilicate, the mass ratio of the polyaniline-modified cellulose to the polydimethylsiloxane stock solution is 0.05:1; the mass ratio of the polydimethylsiloxane stock solution to tetraethyl orthosilicate is 10:1; The mass concentration of the mixed office waste pulp is 1%; The process conditions of the electrical treatment are: the friction voltage of the friction nanogenerator is 30-120V, the stirring speed is 300-600r / min, and the electrical treatment time is 5-20min.

2. The method for deinking mixed office waste paper using TENG electrical treatment according to claim 1, characterized in that: The PANI-modified cellulose / PDMS composite material is made into a film material, a conductive tape is attached to the back of the film material as the negative electrode friction material, and paper with a conductive tape attached to the back is used as the positive electrode friction material to make a friction nanogenerator. The friction nanogenerator generates electricity through contact separation, and then converts the alternating current into direct current through a rectifier bridge. The DC current is then passed through electrodes into mixed office waste paper pulp for electrical treatment under stirring conditions.

3. The method for deinking mixed office waste paper using TENG electrical treatment according to claim 1, characterized in that: The method also includes flotation deinking after electrical treatment. The process conditions of the flotation deinking are: the deinking agent is OP-10, the addition amount is 0.06%, pH=7, temperature is 50°C, flotation concentration is 1%, and flotation time is 10 minutes.

4. The method for deinking mixed office waste paper using TENG electrical treatment according to claim 1, characterized in that: The mass ratio of the aniline, cellulose and ammonium persulfate is 1:1:1.

25.

5. The method for deinking mixed office waste paper using TENG electrical treatment according to claim 1, characterized in that: The curing is carried out in an oven at 70°C.

Images