A novel decolorizing agent for dyeing wastewater from mobile phone and tablet computer production, its preparation method and application

Abstract

This invention discloses a novel composite decolorizing agent for dyeing wastewater from mobile phone and tablet computer manufacturing, its preparation method, and its application, belonging to the field of industrial wastewater treatment technology. The decolorizing agent is composed of inorganic and organic components through physical mixing. The inorganic component is polyaluminum chloride, and the organic components include cationic polyacrylamide and chitosan-based adsorption synergists. Its preparation methods mainly include two routes: a simple blending method or a pre-modification method, both completed at room temperature through solution mixing and maturation, resulting in a simple process. Through the synergistic effect of its components, this invention achieves extremely high decolorization rates and COD removal rates for acidic, reactive, and disperse dyes in wastewater. It also effectively complexes trace heavy metal ions. The raw materials for this decolorizing agent are readily available, cost-effective, have a wide pH range, and produce flocs with rapid settling speed, providing an economical and simple solution for the efficient pretreatment of complex dyeing wastewater from the electronic equipment industry.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment technology, and in particular to a novel decolorizing agent for dyeing wastewater from the production of mobile phones and tablet computers, its preparation method, and its application. Background Technology

[0002] With the rapid development of the consumer electronics industry, the production scale of devices such as mobile phones and tablets continues to expand. In the production process of their plastic shells, metal frames and glass covers, a large number of dyeing processes such as spraying, dyeing and anodizing are involved, which in turn generate dyeing wastewater with complex composition and high pollutant concentration. This type of wastewater is usually characterized by extremely high color, high COD value and obvious water quality fluctuations. The dyes contained in it are mostly structurally stable and difficult to biodegrade acid dyes, reactive dyes and disperse dyes. At the same time, it contains a variety of auxiliaries and trace amounts of heavy metal ions. If it is discharged directly without effective treatment, it will cause serious pollution to the water environment.

[0003] Currently, the decolorization treatment of this type of industrial dyeing wastewater mainly relies on the following technologies: Traditional inorganic flocculant methods, such as polyaluminum chloride (PAC) and polyferric sulfate (PFS), mainly work by charge neutralization and compression of the double electric layer. They are effective for colloidal dyes, but have limited removal rates for water-soluble dye molecules. They also generally suffer from problems such as large dosage, large amount of sludge, high water content, and high subsequent treatment costs. For complex dyeing wastewater from the electronics industry, the decolorization effect is often incomplete, making it difficult to consistently meet high emission standards.

[0004] Synthetic organic polymer flocculant / decolorizing agent method: such as polyacrylamide (PAM) series products, especially cationic (CPAM). These agents mainly form large flocs through adsorption bridging. However, when using CPAM alone to treat high-concentration, multi-component dyeing wastewater, its long-chain molecules are easily encapsulated by a large amount of dissolved organic matter in the wastewater and become inactive, resulting in decreased efficiency, increased cost, and strong specificity, with poor adaptability to different types of dyes.

[0005] Advanced oxidation methods and biological treatment methods, such as Fenton oxidation, ozone oxidation, or special microbial degradation, can achieve deep degradation, but they generally have limitations such as large equipment investment, high operating costs, harsh reaction conditions (such as the need for precise control of pH and temperature), potential secondary pollution (such as iron sludge, residual oxidants), or long treatment cycles. These methods are difficult to promote as an economical and convenient pretreatment or deep treatment unit in the majority of electronic product manufacturing enterprises.

[0006] To address the aforementioned issues, a novel decolorizing agent for dyeing wastewater from mobile phone and tablet computer production, along with its preparation method and application, is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a novel decolorizing agent for dyeing wastewater from the production of mobile phones and tablet computers, its preparation method, and its application, in order to solve the problems mentioned in the background art regarding the existing novel decolorizing agents for dyeing wastewater from the production of electronic devices, which have high decolorization efficiency, strong adaptability, simple preparation and use, and low overall cost.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a novel decolorizing agent for dyeing wastewater from mobile phone and tablet computer production, its preparation method and application, which is composed of inorganic and organic components through physical mixing and compounding, wherein the inorganic component is polyaluminum chloride, and the organic component includes cationic polyacrylamide and chitosan-based adsorption synergists.

[0009] Preferably, the chitosan-based adsorption synergist is carboxymethyl chitosan, and the mass ratio of the inorganic component to the organic component is 3:1 to 15:1 based on the mass of the solid effective ingredient, and the mass ratio of the chitosan adsorption synergist to the cationic polyacrylamide is 1:10 to 2:1.

[0010] Preferably, it includes the following steps: S1: Prepare aqueous solutions of inorganic components and aqueous solutions of organic composites containing chitosan-based adsorption synergists and cationic polyacrylamide, respectively. S2: Under stirring conditions, the inorganic component aqueous solution is mixed with the organic composite aqueous solution, and after aging, a liquid composite decolorizing agent is obtained.

[0011] Preferably, in step S1, the preparation of the organic composite aqueous solution includes: dissolving the chitosan adsorption synergist in an acetic acid solution with a concentration of 0.5%-2%, and then mixing it with a cationic polyacrylamide aqueous solution, wherein the concentration of the chitosan adsorption synergist in the organic composite aqueous solution is 0.5%-3%, and the concentration of the cationic polyacrylamide is 0.05%-0.5%.

[0012] Preferably, it includes the following steps: S1: Carboxymethyl chitosan is modified by carboxymethylation to prepare an aqueous solution of carboxymethyl chitosan; S2: Mix the carboxymethyl chitosan aqueous solution with the cationic polyacrylamide aqueous solution and perform pre-composite treatment to obtain a pre-prepared organic composite liquid; S3: Mix the aqueous solution of polyaluminum chloride with the pre-prepared organic composite liquid and allow it to mature to obtain the final product.

[0013] Preferably, in step S, the pre-composite process is carried out at room temperature for 1-2 hours, and the mass ratio of the carboxymethyl chitosan to the cationic polyacrylamide is 1:5 to 1:1.

[0014] Preferred application is in industrial wastewater containing acid dyes, reactive dyes, or disperse dyes.

[0015] Preferably, the industrial wastewater is dyeing wastewater generated during the production of plastic casings, metal frames, or glass covers for mobile phones or tablets.

[0016] Preferably, when applying the compound decolorizing agent, the pH of the wastewater is adjusted to 6.0-8.5, and the agent is added at a dosage of 50-800 mg / L, followed by rapid mixing and slow flocculation reaction.

[0017] Preferably, the stirring speed for rapid mixing is 150-300 rpm for 1-3 minutes, and the stirring speed for slow flocculation is 40-80 rpm for 10-20 minutes.

[0018] Compared with the prior art, the beneficial effects of the present invention are: Significantly improved removal efficiency: This invention utilizes the synergistic effect of inorganic components (PAC) and organic components (CPAM and chitosan-based synergists). Chitosan (especially carboxymethyl chitosan) has a strong adsorption and chelation capacity for anionic dye molecules, which makes up for the shortcomings of traditional flocculants in removing soluble dyes. Experiments show that for complex wastewater containing multiple dyes from the production of mobile phones and tablets, the decolorization rate of this invention can stably reach 90% to 98% or more, and the COD removal rate is significantly improved simultaneously, with the effluent color being much lower than that of traditional methods.

[0019] Fast settling speed and simple sludge treatment: Because CPAM is based on micro-flocs that have undergone preliminary coagulation by PAC and modified by chitosan, the resulting flocs are large in size, dense in structure and high in strength. Its settling speed can be 30%-50% faster than using the same dose of PAC or CPAM alone, which greatly shortens the water treatment cycle and improves the treatment capacity of the facility. At the same time, the sludge is smaller in volume and has higher density, which reduces the difficulty and cost of subsequent sludge dewatering and disposal.

[0020] The preparation process is simple and the cost is controllable: All the raw materials used in this invention (PAC, CPAM, chitosan) are common bulk chemical or biomass products on the market, and no rare or special materials are required. The preparation method adopts a simple physical mixing and compounding process, which can be carried out at room temperature and pressure, and is easy to achieve large-scale production.

[0021] High adaptability: This composite decolorizing agent maintains high efficiency within a wide pH range (6.0-8.5), and is highly tolerant to pH fluctuations in raw wastewater, reducing the operational burden of frequent pH adjustments and chemical consumption. Its multiple mechanisms of action enable it to have good decolorization effects on dyes with various charge properties and molecular structures, such as acidic, reactive, and dispersed dyes. It is particularly suitable for treating mixed dyeing wastewater from the electronics industry with complex and variable compositions.

[0022] It also has heavy metal removal capabilities: the chitosan component can effectively complex and capture trace heavy metal ions (such as Cu²⁺) in wastewater. + Ni² + This enables the synergistic removal of dyes and heavy metals.

[0023] Improved environmental friendliness: Compared to some traditional decolorizing agents that may introduce new environmental risks (such as the toxicity of certain synthetic organic compounds), the chitosan used in this invention is a natural biodegradable polymer material with good environmental compatibility. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.

[0025] Example Example 1: Preparation of a novel decolorizing agent by blending method and its application Raw material: Polyaluminum chloride (PAC, liquid, Al2O3 content 10%) Chitosan (degree of deacetylation ≥ 85%) Cationic polyacrylamide (CPAM, 40% ionicity, 8 million molecular weight) glacial acetic acid Deionized water.

[0026] Preparation steps: S1: Preparation of polyaluminum chloride solution: Take commercially available polyaluminum chloride liquid, dilute it with deionized water to an Al2O3 content of 5%, and stir well for later use.

[0027] S2: Preparation of organic composite liquid: In a container with a stirrer, add 500ml of deionized water and 5ml of glacial acetic acid (1% acetic acid solution), slowly add 5g of chitosan powder, and stir until completely dissolved. Take another 0.5g of CPAM powder and slowly add it to another 200ml of water, stirring until completely dissolved. Slowly add the CPAM solution to the chitosan acetic acid solution and stir at low speed to mix evenly. Finally, an organic composite liquid with a chitosan concentration of about 0.7% and a CPAM concentration of about 0.07% is obtained.

[0028] S3: Composite: At a stirring speed of 300 rpm, the polyaluminum chloride solution (approximately 10 g based on Al2O3 solids) is slowly added to the organic composite liquid. After the addition is complete, stirring is maintained for 30 minutes, and then the mixture is allowed to stand and mature for 60 minutes to obtain a light yellow, uniform, and viscous composite decolorizing agent. The mass ratio of PAC (based on solids) to the total solids of organic components (chitosan and CPAM) in the product is approximately 8:1, and the mass ratio of chitosan to CPAM is 10:1.

[0029] Application effect test: Wastewater sample: Wastewater from a mobile phone casing spraying workshop, mainly containing disperse dyes and surfactants, pH=8.5, color (dilution factor method) 800 times, COD 850mg / L.

[0030] Treatment process: Take 500ml of wastewater into a beaker, adjust the pH to 7.5 with dilute sulfuric acid, add MOIC-1 decolorizing agent solution (dosage is 300mg / L based on effective solids), stir rapidly at 200rpm for 2 minutes, then stir slowly at 60rpm for 15 minutes, let stand for 30 minutes to settle, and then take the supernatant for testing.

[0031] Results: The decolorization rate reached 95% (color decreased to 40 times), the COD removal rate reached 72%, the flocs were large and dense, and the settling speed was about 40% faster than when using the same dose of PAC alone.

[0032] Example 2: Preparation of a novel decolorizing agent by pre-modification method and its application Raw materials: Based on the raw materials in Example 1, sodium hydroxide, chloroacetic acid, and ethanol are added.

[0033] Preparation steps: S1: Preparation of carboxymethyl chitosan (CMC): Weigh 10g of chitosan, disperse it in 100ml of 40% sodium hydroxide solution, swell overnight, add 15g of chloroacetic acid and 100ml of isopropanol, react at 60℃ for 4 hours, after the reaction is completed, wash the product with 70% ethanol until neutral, and dry to obtain carboxymethyl chitosan (degree of substitution about 0.5).

[0034] S2: Pre-prepared organic composite liquid: Prepare a 2% aqueous solution of the self-made CMC and a 0.2% aqueous solution of CPAM (same as in Example 1). Mix the two according to the dry basis mass ratio of CMC to CPAM of 1:2, and stir at 100 rpm for 1.5 hours at room temperature to obtain a uniform and transparent pre-prepared organic composite liquid.

[0035] S3: Final compounding: Take PAC solution (same as in Example 1, Al2O3 content 5%), add it to the pre-prepared organic composite liquid at a mass ratio of 6:1 while stirring, and continue stirring and mixing for 45 minutes to obtain the finished composite decolorizing agent.

[0036] Application effect test: Wastewater sample: Taken from an anodizing and dyeing line for metal frames of tablet computers. It mainly contains acidic dyes and metal ions, with a pH of 3.5, a color intensity of 1200 times, a COD of 780 mg / L, and trace amounts of Cu²⁺. + (~2mg / L).

[0037] Treatment process: Take 500ml of wastewater, adjust the pH to 7.0 with sodium hydroxide, add MOIC-2 decolorizing agent (dosage 250mg / L), stir quickly at 250rpm for 1.5 minutes, then stir slowly at 50rpm for 20 minutes, and let it stand to settle.

[0038] Results: The decolorization rate reached over 98%, the COD removal rate reached 75%, the supernatant was clear, and Cu²⁺ was negative. + The ion removal rate exceeds 90% (residual concentration <0.2mg / L), the floc structure is more compact, and the moisture content is low.

[0039] Working principle of this invention: The novel decolorizing agent described in this invention, after being compounded in a specific manner, produces multiple synergistic and sequential effects in wastewater, including adsorption, charge neutralization, bridging, and trapping, thereby achieving efficient and deep decolorization of complex dyeing wastewater.

[0040] The principle is explained as follows: Rapid charge neutralization and primary condensation: 1. Active component: Polyaluminum chloride (PAC).

[0041] Mechanism of action: PAC hydrolyzes in water to form a series of highly positively charged polynuclear hydroxyl complexes (such as [Al... 13 O4(OH) 24 ] 7+ These highly positively charged species, when added to negatively charged dye colloidal particle wastewater, can rapidly neutralize the negative charge on the surface of the colloidal particles, compress their electric double layer, and lower the Zeta potential to near the isoelectric point, thereby disrupting the stability of the colloid, causing it to destabilize and aggregate, forming a large number of tiny flocs. This step is the rapid start-up stage of the entire flocculation process.

[0042] 2. Specific adsorption and ion exchange: Active component: Chitosan or its modified form (especially carboxymethyl chitosan, CMC).

[0043] Mechanism of action: At the same time or shortly after PAC completes the initial charge neutralization, the dissolved chitosan / CMC molecules begin to exert their effects.

[0044] Adsorption: The abundant amino (-NH2) and hydroxyl (-OH) groups on its molecular chain have extremely strong hydrogen bonding, van der Waals forces and electrostatic attraction to a variety of dye molecules (especially anionic dyes), which can directly adsorb soluble dye molecules in water that have not yet been condensed by PAC onto its chain.

[0045] Chelation: Amines react with transition metal ions (such as Cu²⁺) in wastewater. + Ni² + It has excellent coordination chelation ability, which can capture and fix it.

[0046] Patch effect: Chitosan / CMC molecules that have adsorbed dyes or metal ions undergo changes in their charge and morphology, and can act as "active patches" to further attach to the surface of micro-flocs formed by PAC, changing their surface properties and preparing for subsequent bridging.

[0047] 3. Highly efficient bridging and floc growth: Active ingredient: cationic polyacrylamide (CPAM).

[0048] Mechanism of action: CPAM is a long-chain polymer. After the micro-flocs have been formed and modified with chitosan / CMC, the long-chain molecules of CPAM can span multiple micro-flocs at the same time. The cationic groups on its chains are electrostatically bonded to the negatively charged micro-floc sites, while its long molecular chains connect, bind and entangle countless micro-flocs together through physical bridging, forming macro-flocs with larger size and denser structure. This process greatly accelerates the growth and sedimentation of the flocs.

[0049] 4. The final effect of collaboration and net capture: Sequential Synergy: This invention ensures an optimized sequence of action: PAC acts first, followed by deep adsorption and characteristic modification of carboxymethyl chitosan, and finally macroscopic bridging by CPAM. This sequence of first coagulation, then adsorption modification, and finally bridging avoids the premature encapsulation and inactivation of CPAM chains by large amounts of dissolved substances in wastewater, and also makes the adsorption sites of carboxymethyl chitosan more easily exposed.

[0050] Network capture: The final three-dimensional structure of PAC micro-flocs-CMC adsorption layer-CPAM bridging network acts like a falling filter during sedimentation, capturing and sweeping up finer particles and colloids remaining in the water, achieving deep purification.

[0051] This invention integrates and synergizes the functions of inorganic coagulants (PAC), natural biosorbents (chitosan), and synthetic polymeric flocculants (CPAM) through a simple physical compounding process. Its improvements lie in overcoming the shortcomings of single PAC in terms of low removal rate of water-soluble dyes and loose flocs, and compensating for the lack of deactivation of single CPAM in high-concentration and complex wastewater. Furthermore, by introducing chitosan (especially after modification), the product has a dual synergistic effect in adsorbing soluble dyes and chelating heavy metals. Ultimately, it achieves faster sedimentation speed, higher decolorization rate and COD removal rate, and better heavy metal ion removal effect with a smaller dosage over a wider pH range. It is suitable for the treatment of dyeing wastewater from electronic equipment manufacturing with fluctuating composition.

[0052] Although embodiments of the present invention have been shown and described, these specific embodiments are merely explanations of the invention and are not intended to limit it. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. After reading this specification, those skilled in the art may make modifications, substitutions, and variations to the embodiments as needed without departing from the principles and spirit of the invention, but such modifications, substitutions, and variations are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A novel decolorizing agent for dyeing wastewater from mobile phone and tablet computer production and its preparation method, characterized in that: It is composed of inorganic and organic components through physical mixing and compounding, wherein the inorganic component is polyaluminum chloride, and the organic component includes cationic polyacrylamide and chitosan-based adsorption synergists.

2. The novel decolorizing agent for dyeing wastewater from mobile phone and tablet computer production and its preparation method according to claim 1, characterized in that: The chitosan-based adsorption synergist is carboxymethyl chitosan. Based on the mass of the solid effective component, the mass ratio of the inorganic component to the organic component is 3:1 to 15:1, and the mass ratio of the chitosan adsorption synergist to the cationic polyacrylamide is 1:10 to 2:

1.

3. A novel decolorizing agent for dyeing wastewater from mobile phone and tablet computer production, and its preparation method, as described in claims 1-2, characterized in that: Includes the following steps: S1: Prepare aqueous solutions of inorganic components and aqueous solutions of organic composites containing chitosan-based adsorption synergists and cationic polyacrylamide, respectively. S2: Under stirring conditions, the inorganic component aqueous solution is mixed with the organic composite aqueous solution, and after aging, a liquid composite decolorizing agent is obtained.

4. The novel decolorizing agent for dyeing wastewater from mobile phone and tablet computer production, and its preparation method, as described in claim 3, is characterized in that: In step S1, the preparation of the organic composite aqueous solution includes: dissolving the chitosan adsorption synergist in an acetic acid solution with a concentration of 0.5%-2%, and then mixing it with a cationic polyacrylamide aqueous solution, wherein the concentration of the chitosan adsorption synergist in the organic composite aqueous solution is 0.5%-3%, and the concentration of the cationic polyacrylamide is 0.05%-0.5%.

5. A novel decolorizing agent for dyeing wastewater from mobile phone and tablet computer production, and its preparation method, as described in claims 1-2, characterized in that: Includes the following steps: S1: Carboxymethyl chitosan is modified by carboxymethylation to prepare an aqueous solution of carboxymethyl chitosan; S2: Mix the carboxymethyl chitosan aqueous solution with the cationic polyacrylamide aqueous solution and perform pre-composite treatment to obtain a pre-prepared organic composite liquid; S3: Mix the aqueous solution of polyaluminum chloride with the pre-prepared organic composite liquid and allow it to mature to obtain the final product.

6. The novel decolorizing agent for dyeing wastewater from mobile phone and tablet computer production, and its preparation method, as described in claim 5, is characterized in that: In step S2, the pre-composite process is carried out at room temperature for 1-2 hours, and the mass ratio of the carboxymethyl chitosan to the cationic polyacrylamide is 1:5 to 1:

1.

7. A novel decolorizing agent for dyeing wastewater from mobile phone and tablet computer production, and its preparation method, as described in claims 1-2, characterized in that: Applications in industrial wastewater containing acid dyes, reactive dyes, or disperse dyes.

8. A novel decolorizing agent for dyeing wastewater from mobile phone and tablet computer production, its preparation method, and its application, as described in claim 7, characterized in that: The industrial wastewater refers to the dyeing wastewater generated during the production of plastic casings, metal frames, or glass covers for mobile phones or tablets.

9. The application according to claim 7 or 8, characterized in that: When applying the solution, adjust the pH of the wastewater to 6.0-8.5, add the composite decolorizing agent at a dosage of 50-800 mg / L, and perform rapid mixing and slow flocculation reaction.

10. The application according to claim 9, characterized in that, The rapid mixing is performed at a stirring speed of 150-300 rpm for 1-3 minutes, and the slow flocculation is performed at a stirring speed of 40-80 rpm for 10-20 minutes.