In-situ copolymerization hybrid flocculants, and preparation method and application method thereof
By preparing in-situ copolymerized hybrid flocculants, the segmented in-situ polymerization of inorganic metals, organic monomers, and composite natural polymer materials solves the problems of separation difficulties and environmental impact in the treatment of high water content engineering mud and dredged sludge, achieving efficient flocculation and deep dewatering, and improving floc strength and environmental performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG UNIV OF TECH
- Filing Date
- 2026-03-09
- Publication Date
- 2026-06-12
AI Technical Summary
Existing treatment methods for high water content engineering mud and dredged sludge present challenges such as separation difficulties, significant environmental impact of traditional flocculants, and difficulties in recycling. In particular, inorganic coagulants require large dosages, have low floc strength, rely on chemical monomers for synthetic organic polymers, and have insufficient shear resistance.
In-situ copolymerized hybrid flocculants are used, which are formed by segmented in-situ polymerization of inorganic metals, organic monomers and composite natural polymer materials. This results in flocculants with high flocculation performance and green environmental protection properties. The flocculants include cellulose, pectin and plant tannin phases obtained from agricultural waste treatment, which are combined with Fe³⁺/Al³⁺ ions to form a synergistic mechanism of "rapid destabilization - nucleation and aggregation - long chain bridging - skeleton reinforcement - complexation and cross-linking".
It achieves efficient and rapid flocculation and deep dehydration, with large floc particle size and strong shear resistance, which enhances its green and environmentally friendly properties, reduces dependence on traditional chemical raw materials, and strengthens the structural stability of the floc.
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Figure CN121800301B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of environmental engineering and solid waste resource utilization, and in particular to an in-situ copolymerized hybrid flocculant and its preparation and application methods. Background Technology
[0002] High-water-content engineering mud and dredged sludge are characterized by high fine particle content, stable colloidal systems, and slow natural settling. They typically require chemical conditioning followed by mechanical dewatering to reduce volume. Currently, commonly used chemical conditioning agents mainly include inorganic coagulants (such as iron salts and aluminum salts) and synthetic organic flocculants (such as polyacrylamide). However, inorganic coagulants generally suffer from problems such as high dosage, low floc strength, pH sensitivity, and susceptibility to re-turbidity; traditional synthetic organic polymers face challenges such as dependence on chemical monomers, environmental risks from residual monomers, and insufficient shear strength of the flocs.
[0003] To enhance green attributes and resource utilization, solid wastes such as red mud, rich in metallic elements like iron and aluminum, have the potential to serve as a source of inorganic multivalent metal ions for coagulation. Natural polymeric flocculants and their modified products are increasingly attracting attention. These materials are widely available, biodegradable, and suitable for reducing the amount of synthetic monomers used or as synergistic agents to enhance floc structure. However, existing technologies mostly employ physical mixing or a staged dosing process of "inorganic preconditioning + organic main conditioning." This approach suffers from drawbacks such as low component synergistic effects, limited synergistic effects, and difficulties in safety management.
[0004] Therefore, developing a novel flocculant that can copolymerize leached metal sources, organic monomers, and natural polymers from solid waste in situ, while taking into account both high-efficiency dewatering performance and green environmental protection properties, has become a key requirement for improving the deep dewatering efficiency of engineering mud. Summary of the Invention
[0005] To address the common problem of separating high-moisture-content engineering sludge from dredged sludge during treatment, and considering the environmental impact and recycling issues associated with traditional flocculant production and use, this invention provides an in-situ copolymerized hybrid flocculant, along with its preparation and application methods. This flocculant enhances floc strength and filter press dewatering performance in sludge flocculation through a synergistic mechanism, achieving rapid flocculation and deep dewatering under varying sludge properties, while also improving its environmental friendliness.
[0006] The present invention is accomplished by the following technical solution: an in-situ copolymerized hybrid flocculant, comprising an inorganic metal, an organic monomer, and a composite natural polymer material package, wherein the flocculant is formed by segmental in-situ polymerization of the inorganic metal, the organic monomer, and the composite natural polymer material package, and the inorganic metal is the leachate of treated metal solid waste.
[0007] Furthermore, the composite natural polymer material package includes a cellulose phase, a pectin phase, and a plant tannin phase obtained from agricultural waste treatment, wherein the solid mass ratio of the cellulose phase: pectin phase: plant tannin phase is (3~10):(1~5):(0.5~3).
[0008] Furthermore, the metal solid waste leachate contains Fe. 3+ And Al 3+ Metal inorganic salt type leaching solution of ions, wherein Fe 3+ With Al 3+ The total concentration was 0.05~2.0 mol / L, Fe 3+ :Al 3+ The molar ratio is (0.2~5):1.
[0009] Furthermore, the above-mentioned method for preparing an in-situ copolymerized hybrid flocculant employs a segmented in-situ approach, first inducing polymerization and then performing skeletal hybridization. The specific steps are as follows:
[0010] S1. Pre-dissolution and deoxygenation,
[0011] The NVCL organic monomers are dissolved in the detoxified solid waste leachate, and an inert gas is introduced to isolate oxygen.
[0012] S2. In-situ induced prepolymerization
[0013] Initiator is added and the temperature is controlled at 40~75℃ to start polymerization until the conversion rate of NVCL organic monomers reaches 20~60%, and a highly coordinated organic-inorganic long-chain intermediate is formed in the system.
[0014] S3. Copolymerization hybridization
[0015] In the S2 polymerization system, a composite natural polymer material package is introduced. By utilizing the continuous growth of active chain segments in the later stage of polymerization, organic long chains are generated and connected around the iron and aluminum ions and cellulose backbone. The cellulose phase is embedded into the growing polymer network through spatial connections to form an integrated backbone support structure.
[0016] S4. Purification process,
[0017] The S3 copolymerization and hybridization reaction continues until the conversion is complete. The residual monomers are removed by demolding or vacuum devolatilization to ensure that the residual NVCL is ≤0.05 wt%, thus obtaining the finished flocculant.
[0018] Furthermore, the preparation steps of the composite natural polymer material package include the following:
[0019] 1) Cellulose phase: Papermaking sludge is mechanically dewatered, washed and dissociated by water, and separated by hydrocyclone to obtain cellulose pulp;
[0020] 2) Pectin phase: Citrus peel or apple pomace is extracted with acidified hot water and purified by membrane separation to obtain a pectin phase solution or pectin powder;
[0021] 3) Plant tannin phase: Plant residues are extracted with hot water and then adsorbed and enriched with macroporous resin to obtain a tannin-rich eluent. Finally, the alcohol is removed under reduced pressure and the eluent is concentrated to a solid content of 5-30 wt%, so that the total tannin content is ≥40 wt%.
[0022] 4) The three phases are compounded to form a natural polymer material package. The solid mass ratio of the three phases in the material package is set as cellulose: pectin: tannin = (1~20):(1~10):(0.5~8). The solid content of the material package is calibrated to 2~15 wt%. The natural polymer package mother liquor is prepared, or it is further dried to prepare powder.
[0023] 5) Standardized quality control of natural polymer materials: the cellulose phase is controlled by ash content and fiber length distribution, the pectin phase is controlled by galacturonic acid content and solution viscosity, and the tannin phase is controlled by total tannin content and color / oxidative stability.
[0024] Furthermore, the detoxification step of the solid waste leachate in S1 is as follows:
[0025] 1) Dealkali removal: Grind the iron-aluminum rich solid waste to D90≤150um, and then wash it with water to remove alkali, so that pH≤10;
[0026] 2) Acid leaching: The solid waste after alkali removal is leached with the leaching medium, wherein the leaching temperature is 40~90℃ and the pH of the leaching solution is 0.5~25. After leaching, the solid and liquid are separated by pressure filtration or centrifugation to obtain crude leaching solution.
[0027] 3) Fine purification: The crude leachate is subjected to sequential removal of anionic toxic substances and selective chelation adsorption of cationic toxic substances. The pH of the treatment is controlled at 2.0~5.0. After the detoxification treatment, the total concentration of at least two heavy metal ions among As, Cr, Pb, Cd and Hg in the crude leachate is ≤1 mg / L.
[0028] Furthermore, the NVCL organic monomer has a mass fraction of 5-35 wt% in the initial reaction system, and its 1-10 wt% aqueous solution has a viscosity of 0.2-20 Pa·s at 25°C. The organic monomer forms a long organic chain in the polymerization process, which serves as the bridging host.
[0029] Furthermore, during the S3 synergistic copolymerization hybridization stage, the system pH is adjusted to 3.5–5.0, and the shear rate is controlled at 50–300 s⁻¹. -1 This promotes the coordination complexation between pectin, tannins and metal ions, as well as the spatial anchoring of cellulose.
[0030] Furthermore, the cellulose phase is 0.1~20 wt%, the ash content is ≤5 wt%, and the median fiber length is 0.2~2.0 mm; the pectin phase is 0.1~10 wt%, and the viscosity of a 1 wt% pectin solution at 25°C is 10~300 mPa·s; the tannin phase is 0.05~8 wt%.
[0031] Furthermore, an application method for an in-situ copolymer hybrid flocculant employs a one-step conditioning mode, with the following steps:
[0032] 1) The hybrid flocculant is directly added to the sludge to be treated, with a dosage of 80~800 mg / L based on active solids;
[0033] 2) Perform rapid mixing and slow mixing sequentially to form large-particle-size, high-strength shear-resistant flocs with a physical fibrous skeleton and a particle size of 0.5~8 mm. The G-value of the rapid mixing stage is 200~800 s. -1 The G value during the slow mixing phase is 20~120 s. -1 ;
[0034] 3) Solid-liquid separation: The flocs after conditioning in step 2) are directly fed into plate and frame filter press, belt filter press, or centrifugal dewatering equipment.
[0035] Beneficial effects of this invention:
[0036] (1) Green, low-carbon and high degree of solid waste resource utilization: This invention uses the detoxified metal solid waste leachate as the source of Fe³⁺ / Al³⁺ inorganic components, and introduces natural polymers such as papermaking sludge cellulose, fruit and vegetable processing waste pectin and plant tannins to realize the recycling of industrial solid waste and agricultural processing waste. While ensuring flocculation performance, it reduces the dependence on traditional chemical raw materials and improves the overall environmental friendliness and sustainability.
[0037] (2) Highly integrated structure and synergistic flocculation mechanism: This invention couples the charge neutralization effect of the metal source in the solid-liquid leachate, the bridging effect of the NVCL organic long chain, and the complexation enhancement effect of the natural polymer material package to form a physical-chemical dual synergistic mechanism of "rapid destabilization - nucleation and aggregation - long chain bridging - skeleton reinforcement - complexation and cross-linking".
[0038] (3) Large floc size and strong shear resistance: The cellulose phase in the natural polymer material package provides skeletal support, the pectin phase forms a network structure with multivalent metal ions, and the tannin phase provides complexation enhancement, making the flocs less prone to breakage under shearing action such as stirring and pumping, and enhancing the dewatering effect of pressure filtration or centrifugation. Attached Figure Description
[0039] Figure 1 This is a schematic diagram of the preparation process of an in-situ copolymerized hybrid flocculant;
[0040] Figure 2 This is a schematic diagram of the structure of an in-situ copolymer hybrid flocculant;
[0041] Figure 3 This is a schematic diagram of the application process of an in-situ copolymerized hybrid flocculant;
[0042] Figure 4 This is a schematic diagram comparing the flocculant synthesis effects of hybrid flocculants at different conversion rates. Detailed Implementation
[0043] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.
[0044] Reference Figures 1-4 As shown, the present invention provides an in-situ copolymerized hybrid flocculant, comprising an inorganic metal, an organic monomer, and a composite natural polymer material package. The flocculant is formed by segmental in-situ polymerization of the inorganic metal, the organic monomer, and the composite natural polymer material package, wherein the inorganic metal is a treated metal solid waste leachate.
[0045] Specifically, the organic monomer is NVCL (N-vinylcaprolactam) organic monomer, with a mass fraction of 5-35 wt% in the initial reaction system, and the long organic chain formed by polymerization serves as the bridging host. The composite natural polymer material package serves as a hybrid reinforcing monomer, composed of a cellulose phase (source: papermaking sludge fiber), a pectin phase (source: citrus peel / apple pomace), and a plant tannin phase (source: tea residue / nut shell / bark extraction residue, etc.) obtained from agricultural waste treatment. The three components are combined to form a material package, which is used to enhance the floc skeleton, improve shear resistance, and promote coordination / weak cross-linking with Fe³⁺ / Al³⁺. The solid mass ratio of cellulose phase: pectin phase: plant tannin phase is (3-10):(1-5):(0.5-3). The metal solid waste leachate serves as the polymerization reaction medium, containing Fe 3+ Al 3+ The leachate is a metal inorganic salt type containing ions and other ions. The total concentration of Fe3+ and Al3+ in the leachate is 0.05~2.0 mol / L (preferably 0.10~1.0 mol / L), and the Fe3+:Al3+ molar ratio is (0.2~5):1 (preferably (0.5~2):1). After purification treatment, the total amount of toxic heavy metal ions (As, Cr, Pb, Cd, Hg, etc.) is controlled to ≤5 mg / L (preferably ≤1 mg / L), and meets the relevant discharge and disposal requirements for mud dewatering in the target area.
[0046] Reference Figures 1-2As shown, the above-mentioned method for preparing an in-situ copolymerized hybrid flocculant employs a segmented in-situ approach, first inducing polymerization and then performing skeletal hybridization. The specific steps are as follows:
[0047] S1. Pre-dissolution and deoxygenation.
[0048] The NVCL organic monomer is dissolved in a detoxified solid waste leachate, and an inert gas is introduced to isolate oxygen. Specifically, the mass fraction of the NVCL organic monomer in the initial reaction system is 5-35 wt% (preferably 10-25 wt%), and its 1-10 wt% aqueous solution has a viscosity of 0.2-20 Pa·s at 25°C. Inert gas is introduced for deoxygenation for 15-60 min to ensure dissolved oxygen ≤0.5 mg / L.
[0049] S2. In-situ induced prepolymerization.
[0050] Initiator is added and polymerization is initiated at 40-75℃ (preferably 50-60℃) until the NVCL organic monomer conversion reaches 20-60%. The organic monomers polymerize within the system to form highly coordinated organic-inorganic long-chain intermediates, which serve as the main body for long-chain bridging. The initiator monomer mass is 0.1-0.5 wt%, and a redox initiator is preferred.
[0051] S3. Copolymerization hybridization.
[0052] A composite natural polymer material package was introduced into the polymerization system in S2. The pH of the system was adjusted to 3.5-5.0, and the mixing shear rate was controlled at 50-300 s. -1 (Preferred time: 50~200s) -1 This process promotes coordination and complexation between pectin, tannins, and metal ions, as well as the spatial anchoring of cellulose. The composite natural polymer material includes a cellulose phase, a pectin phase, and a plant tannin phase obtained from agricultural waste treatment. The pectin and plant tannin phases bind to metal ions through coordination. Utilizing the continuous growth of active chain segments in the later stages of polymerization, long organic chains are generated and linked around the iron and aluminum ions and the cellulose backbone. The cellulose phase embeds itself into the growing polymer network through spatial linkages, forming an integrated skeletal support structure.
[0053] S4. Purification process.
[0054] The S3 copolymerization and hybridization reaction is carried out until the conversion is complete, with a total reaction time of 6-9 hours. Residual monomers are then removed by demolding or vacuum devolatilization to ensure residual NVCL ≤ 0.05 wt%, yielding the final flocculant product.
[0055] Specifically, in the above-mentioned flocculant preparation method, the composite natural polymer material package is obtained by purifying and compounding three parts: "cellulose phase (papermaking sludge fiber) + pectin phase (citrus peel / apple pomace) + tannin phase (grape pomace / tea residue / nut shell / bark residue)". The specific preparation steps include the following:
[0056] 1) Cellulose phase: Papermaking sludge is mechanically dewatered, washed and dissociated by water and separated by hydrocyclone to extract and purify cellulose pulp.
[0057] Specific steps: a. Mechanically dewater the papermaking sludge to achieve a solid content of 20-45 wt% (preferably 25-35 wt%), then pulp it using a water washing and dissociation method, controlling the pulp solid content to 1-5 wt%, and stirring and shearing for 200-800 s. -1 a. Perform sieving (5-20 min) to break up agglomerates and release fibers. b. Perform sieving (0.15-1.0 mm sieve) to remove plastic, sand, and large particulate impurities. c. Then use hydrocyclone / cyclone separation to remove high-density inorganic filler, with a feed pressure of 0.10-0.30 MPa, a single residence time of 10-60 s, repeated 1-3 times, to reduce the ash content to ≤15 wt% (preferably ≤5 wt%). d. For recycled paper sludge, a flotation deinking unit can be used, with an air flow rate of 0.2-1.0 L / L·min and a residence time of 5-20 min. e. Perform countercurrent washing, with a liquid-to-solid ratio (L / S) of 3-10 L / kg (based on dry solids), 5-15 min per stage, repeated 2-5 times, to stabilize conductivity and significantly reduce soluble impurities. f. Finally, obtain cellulose pulp, controlling the median fiber length to 0.2–2.0 mm (or even smaller equivalent length after mechanical microfibrillation), and calibrate the pulp solids content to 1–6 wt% (preferably 2–4 wt%) for later use. If a dry powder product is required, the pulp can be dehydrated and vacuum / hot air dried at 40–60°C to a moisture content ≤10 wt%.
[0058] 2) Pectin phase: Citrus peel or apple pomace is extracted with acidified hot water and purified by membrane separation to obtain a pectin phase solution or pectin powder.
[0059] Specific steps: a. Wash citrus peels or apple pomace to remove sugar and sand, then wet-crush to a particle size of 1-5 mm, and extract pectin using acidified hot water extraction. The extraction liquid-to-solid ratio (L / S) is 5-20 L / kg (based on dry solids), the extraction temperature is 60-90℃ (preferably 70-85℃), the extraction time is 0.5-3 h (preferably 1-2 h), and the extraction pH is controlled at 1.5-3.0 (preferably 2.0-2.6). b. After extraction, perform solid-liquid separation by pressure filtration / centrifugation, followed by clarifying microfiltration (pore size 0.2-1.0 μm) to remove suspended solids. c. Then, purify by membrane separation: ultrafiltration membrane with a molecular weight cutoff of 10-100 kDa (preferably 30-50 kDa) removes large molecular impurities such as proteins and pigments. d. Subsequently, desalting and small molecule sugar removal are performed using nanofiltration (cutoff of 200-500 Da) or reverse osmosis, significantly reducing conductivity and obtaining a pectin-rich solution.
[0060] The pectin-enriched solution can be concentrated under vacuum to a solid content of 2-10 wt% (preferably 3-6 wt%), and then spray-dried or vacuum-dried (40-70 °C) to obtain pectin powder; or it can be used directly as a concentrated solution. The solution viscosity of the pectin phase (1 wt%, 25 °C) is preferably controlled at 10-300 mPa·s.
[0061] 3) Plant tannin phase: Plant residues are extracted with hot water and adsorbed and enriched with macroporous resin to obtain tannin-rich eluent. Finally, the alcohol is removed by vacuum and the solution is concentrated to a solid content of 5~30 wt%, so that the total tannin content is ≥40 wt%.
[0062] The specific steps are as follows: a. Wash and dry the raw materials (grape pomace / tea residue / nut shells / bark residue, etc.), then crush them to a particle size of 0.2~2.0 mm. Extract with hot water to obtain a crude extract. The extract-to-solid ratio (L / S) is 5~30 L / kg (based on dry solids), the extraction temperature is 50~95 ℃ (preferably 70~90 ℃), the extraction time is 0.5~3 h (preferably 1~2 h), and the extraction pH is controlled at 3.0~6.0 (preferably 3.5~5.0) to balance tannin stability and yield; b. After solid-liquid separation, clarify by microfiltration (pore size 0.1~1.0 μm). To improve tannin purity, a combination of membrane separation and adsorption enrichment can be used: first, an ultrafiltration membrane (with a molecular weight cutoff of 1-10 kDa, preferably 3-5 kDa) is used to enrich tannins and allow some small molecules to permeate, then the tannins are selectively adsorbed into a macroporous adsorption resin column at a flow rate of 1-5 BV / h and an adsorption volume of 5-30 BV; subsequently, 2-5 BV of deionized water is used for elution to remove sugars and salts, followed by desorption using an alcohol-water system (alcohol volume fraction 50-80%, desorption volume 2-8 BV) to obtain a tannin-rich eluent; finally, the alcohol is removed under reduced pressure and the solution is concentrated to a solid content of 5-30 wt% (preferably 10-20 wt%), and if necessary, spray-dried / lyophilized to obtain a powder (moisture content ≤10 wt%). The total tannin content of the obtained tannin phase (calculated as equivalent gallic acid) is preferably ≥20 wt% (more preferably ≥40 wt%).
[0063] 4) The three phases are compounded to form a natural polymer material package (mother liquor or powder).
[0064] The specific steps include: a. preparing a uniformly dispersed slurry of 1-4 wt% cellulose, a 0.5-5 wt% solution of pectin, and a 0.5-10 wt% solution of tannin; b. during compounding, first mixing the pectin solution and tannin solution and adjusting the pH to 3.5-5.5 (preferably 4.0-5.0), then applying the mixture at a shear rate of 50-300 s. -1 Under certain conditions, slowly add cellulose slurry and mix for 5-30 min to form a stable composite dispersion system. c. The solid mass ratio of the three phases in the material package can be set as cellulose: pectin: tannin = (1-20):(1-10):(0.5-8) (preferably (3-10):(1-5):(0.5-3)), and the solid content of the material package is calibrated to 2-15 wt% (preferably 5-10 wt%) as the "natural polymer package mother liquor", or further dried to obtain powder (moisture content ≤10 wt%), so as to carry out hybrid construction with subsequent NVCL polymer and detoxified iron-aluminum source.
[0065] 5) Standardized quality control of natural polymer materials: the cellulose phase is controlled by ash content and fiber length distribution, the pectin phase is controlled by galacturonic acid content and solution viscosity, and the tannin phase is controlled by total tannin content and color / oxidative stability.
[0066] The specific control indicators of the final product include: the cellulose phase is 0.1~20 wt% (preferably 0.5~10 wt%), the ash content is ≤15 wt% (preferably ≤5 wt%), and the median fiber length is 0.2~2.0 mm (or the equivalent length is smaller after microfibrillation); the pectin phase is 0.1~10 wt% (preferably 0.3~5 wt%), and the viscosity of a 1 wt% pectin solution at 25°C is 10~300 mPa·s; the tannin phase is 0.05~8 wt% (preferably 0.1~3 wt%).
[0067] The solid waste leachate detoxification step in S1 of the above-mentioned in-situ copolymer hybrid flocculant preparation method is as follows:
[0068] 1) Solid waste pretreatment and dealkali removal.
[0069] The iron-aluminum rich solid waste is ground to D90≤150um (preferably≤75μm); then it is washed with water to remove alkali, wherein the solid-liquid ratio (L / S) is 3~10 L / kg, each stage is stirred for 10~30 min, and the process is repeated for 2~6 stages; the completion of alkali removal is based on the pH of the washed slurry being ≤11 (preferably ≤10) or the conductivity stabilizing, in order to reduce free alkali and soluble salts and reduce subsequent acid consumption.
[0070] 2) Acid leaching to obtain crude leachate.
[0071] In step 1) above, the dealkalized solid waste and leaching medium are leached at a solid-liquid ratio (L / S) of 5~25 L / kg (preferably 8~15 L / kg), wherein the leaching temperature is 40~90℃ (preferably 60~80℃), the leaching time is 0.5~6 h (preferably 1~3 h), and the pH of the leachate is 0.5~2.5 (preferably 1.0~2.0) to promote Fe / Al dissolution and prevent redeposition. After leaching, solid-liquid separation is performed by pressure filtration or centrifugation, with a filtration accuracy preferably of 1~50 μm, to obtain a crude leachate.
[0072] 3) Fine purification.
[0073] a. Clarification pretreatment: The crude leachate is clarified by sedimentation or microfiltration with a microfiltration pore size of 0.1~1.0 μm. After pretreatment, the turbidity is controlled to be ≤50 NTU (preferably ≤10 NTU) to ensure the stable operation of the subsequent adsorption / ion exchange unit.
[0074] b. Detoxification and purification: After pretreatment, the crude leachate undergoes sequential removal of anionic toxicants and selective chelation adsorption of cationic toxicants. Specifically, anionic toxicants (such as As, Cr(VI)) are first subjected to adsorption / ion exchange treatment for 10–60 min (or EBCT in a resin bed for 2–10 min); the pH of the solution is adjusted to 2.0–5.0 (preferably 3.0–4.5) before treatment to balance removal efficiency and Fe / Al stability; then, cationic toxicants (such as Pb²⁺, Cd²⁺, Hg²⁺, Ni²⁺) are subjected to selective chelation adsorption treatment for 10–60 min (or EBCT for 3–15 min), with the pH controlled at 2.0–4.5 (preferably 2.5–4.0), and 1–3 stages are used in series to reduce the risk of penetration; finally, polishing filtration is performed with a pore size of 0.2–5 μm. After detoxification treatment, the total concentration of at least two heavy metal ions among As, Cr, Pb, Cd, and Hg is ≤1 mg / L.
[0075] 4) Calibration and storage stability. The purified leachate is calibrated to a total Fe³⁺+Al³⁺ concentration of 0.05~2.0 mol / L, and the pH of the solution is adjusted to 1.5~4.0 (preferably 2.0~3.5) to improve storage stability; in engineering practice, a total Fe / Al retention rate of ≥70% is preferred, and any deficiency can be achieved through secondary concentration or reconstitution.
[0076] The aforementioned in-situ copolymer hybrid flocculant is suitable for high-cement-content slurry and silt generated in construction and dredging projects, including but not limited to shield tunneling mud, bored pile mud, foundation pit mud, river and lake dredging sediment, and port and waterway dredging silt systems. The water content of the treated slurry / silt is preferably 80-200%, with fine particles (particle size <75 μm) accounting for ≥30% (preferably ≥50%), and the presence of clay minerals (such as illite, montmorillonite, and kaolinite) is permissible. The applicable pH range for the influent is 4-10. When the pH exceeds this range, an alkaline / acidic adjuster can be added to bring it to the target range. The slurry conductivity (characterizing salinity and ionic strength) can be within the range of 0.5-50 ms / cm. For high-salinity silt (such as near-shore dredging silt mixed with seawater), the floc structure stability can be maintained by adjusting the dosage of inorganic iron-aluminum source, using staged addition, or extending the slow mixing time.
[0077] Reference Appendix Figure 3 As shown, the application method of the above-mentioned in-situ copolymer hybrid flocculant adopts a one-step conditioning mode, and the steps are as follows:
[0078] 1) The hybrid flocculant is directly added to the sludge to be treated, with a dosage of 80~800 mg / L based on active solids;
[0079] 2) Perform rapid mixing and slow mixing sequentially to form large-particle-size, high-strength shear-resistant flocs with a physical fibrous skeleton and a particle size of 0.5~8 mm. The G-value of the rapid mixing stage is 200~800 s. -1 The G value during the slow mixing phase is 20~120 s. -1 .
[0080] 3) Solid-liquid separation: The flocs after conditioning in step 2) have the characteristics of large particle size and strong shear resistance, and can be directly fed into dewatering equipment such as plate and frame filter press (pressure 0.3~1.2 MPa), belt filter press and centrifuge.
[0081] Example 1: Integrated conditioning and plate and frame filter press for neutral foundation pit slurry, the specific steps are as follows:
[0082] (1) Component preparation.
[0083] Detoxified solid waste leachate A1: Red mud was subjected to dealkalization, acid leaching, and purification treatment, and Fe was calibrated. 3+ And Al 3+ The total concentration was 0.35 mol / L, Fe 3+ :Al 3+ The molar ratio is 1.2:1. The total amount of toxic heavy metals after purification is ≤1 mg / L.
[0084] Natural Material Package C1: A uniform dispersion of 7 wt% papermaking sludge cellulose (ash content 4.5 wt%), citrus pectin and plant tannins was prepared at a solid mass ratio of 6:3:1.
[0085] (2) Copolymerization and hybridization.
[0086] NVCL monomer was dissolved in leachate A1 to prepare a reaction solution with a monomer mass fraction of 15 wt%. After nitrogen deoxygenation for 30 min, the temperature was raised to 60℃, and 0.2 wt% of initiator (monomer mass) was added. When the polymerization conversion rate reached 40% and the viscosity of the system increased significantly, polymer material package C1 was slowly pumped in. The reaction was continued for 4 h, and after completion, residual monomer was removed by vacuum devolatilization (residual amount ≤ 0.05 wt%). A hybrid flocculant F1 with a solid content of approximately 12 wt% was obtained.
[0087] (3) Application effect.
[0088] The material to be treated is drilling mud from a foundation pit project, with a moisture content of 160% and a fine particle content of 55%. Flocculant F1 (at a dosage of 300 mg / L) is directly added to the mud, and the mixture is rapidly stirred for 30 seconds (G=500 s). -1 Slow mix for 8 minutes (G=60 s) -1After treatment, dense flocs of 2-6 mm are formed. These flocs are then processed in a plate and frame filter press (pressure 0.8 MPa) for 20 minutes. The moisture content of the filter cake is significantly reduced, and there is no clogging of the filter cloth.
[0089] Example 2: Integrated conditioning and centrifugal dewatering of high-salinity dredged sludge, the specific steps are as follows:
[0090] (1) Component preparation.
[0091] Detoxified solid waste leachate A2: Take red mud composite solid waste leachate and calibrate Fe... 3+ And Al 3+ The total concentration was 0.80 mol / L, Fe 3+ :Al 3+ The molar ratio is 0.8:1. The total amount of toxic heavy metals after purification is ≤1 mg / L.
[0092] Natural Material Package C2: To enhance the complexing power, the proportion of tannins was appropriately increased. Paper sludge cellulose (ash content 4.5wt%), citrus pectin and plant tannins were prepared into a 10wt% uniform dispersion at a solid mass ratio of 5:3:2.
[0093] (2) Copolymerization and hybridization.
[0094] NVCL monomer was dissolved in leachate A2 to prepare a reaction solution with a monomer mass fraction of 25 wt%. After nitrogen deoxygenation for 30 min, the temperature was raised to 55℃, and 0.2 wt% of initiator (monomer mass) was added. The polymerization conversion rate was 30%, and polymer material package C2 was added. The reaction was continued for 6 h, and after completion, residual monomer was removed by vacuum devolatilization (residual amount ≤ 0.05 wt%), yielding a hybrid flocculant F2 with a solid content of approximately 14 wt%.
[0095] (3) Application effect.
[0096] The treated material was coastal dredged silt with a water content of 92% and an electrical conductivity of 35 mS / cm. Flocculant F2 (at a dosage of 450 mg / L) was directly added to the sludge, and the mixture was rapidly stirred for 45 s (G=500 s). -1 Mix slowly for 10 minutes (G=60 s) -1 After treatment, dense flocs are formed and good shear resistance is maintained even under high salinity. The flocs are then processed in a centrifuge (centrifugal force 1500g). The separated supernatant has low turbidity, which solves the common problems of floc fragility and severe mud loss under high salinity conditions.
[0097] Example 3: Integrated conditioning and centrifugal dewatering of high-organic-matter sludge, the specific steps are as follows:
[0098] (1) Component preparation.
[0099] Detoxified solid waste leachate A3: Red mud was subjected to dealkalization, acid leaching, and purification treatment, and Fe was calibrated. 3+ And Al 3+ The total concentration was 0.50 mol / L, Fe 3+ :Al 3+ The molar ratio is 2.0:1. The total amount of toxic heavy metals after purification is ≤1 mg / L.
[0100] Natural Material Package C3: Appropriately increase the proportion of tannins to enhance complexing power. Prepare a uniform dispersion of 9 wt% by mixing papermaking sludge cellulose (ash content 4.5 wt%), citrus pectin and plant tannins at a solid mass ratio of 4:4:2.
[0101] (2) Copolymerization and hybridization.
[0102] NVCL monomer was dissolved in leachate A3 to prepare a reaction solution with a monomer mass fraction of 20 wt%. After nitrogen deoxygenation for 30 min, the temperature was raised to 65℃, and 0.25 wt% of initiator (monomer mass) was added. When the polymerization conversion rate reached 40% and the viscosity of the system increased significantly, polymer material package C3 was slowly pumped in. The reaction was continued for 3 h, and after completion, residual monomer was removed by vacuum devolatilization (residual amount ≤ 0.05 wt%), yielding a hybrid flocculant F3 with a solid content of approximately 16 wt%.
[0103] (3) Application effect.
[0104] The material being treated was river dredging slurry with a moisture content of 110% and a high organic matter content. Flocculant F3 (at a dosage of 400 mg / L) was directly added to the slurry, followed by rapid stirring for 40 seconds (G=500 s). -1 Mix slowly for 10 minutes (G=80 s) -1 After treatment, dense flocs are formed and fed into a belt filter press (belt speed 4 m / min). The moisture content of the filter cake is reduced, ensuring stable and continuous sludge discharge and filtrate clarity.
[0105] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. An in-situ copolymerized hybrid flocculant, characterized in that: The flocculant comprises inorganic metals, NVCL organic monomers, and a composite natural polymer material package. It is formed by the segmented in-situ polymerization of these components. The inorganic metals are the leachate from treated solid metal waste. The composite natural polymer material package includes cellulose, pectin, and plant tannin phases obtained from agricultural waste treatment. The segmented in-situ polymerization involves first dissolving the NVCL organic monomers in the treated solid metal waste leachate, then inducing polymerization until the NVCL organic monomer conversion rate reaches 20-60%. Finally, the composite natural polymer material is added for copolymerization and hybridization until the conversion rate is complete.
2. The in-situ copolymer hybrid flocculant according to claim 1, characterized in that: The solid mass ratio of the cellulose phase: pectin phase: plant tannin phase is (3~10):(1~5):(0.5~3).
3. The in-situ copolymer hybrid flocculant according to claim 1 or 2, characterized in that: The metal solid waste leachate contains Fe. 3+ And Al 3+ Metal inorganic salt type leaching solution of ions, wherein Fe 3+ With Al 3+ The total concentration was 0.05~2.0 mol / L, Fe 3 + :Al 3+ The molar ratio is (0.2~5):
1.
4. A method for preparing the in-situ copolymerized hybrid flocculant according to claim 1, characterized in that: The segmented in-situ approach, which involves first inducing polymerization and then hybridizing the framework, is as follows: S1. Pre-dissolution and deoxygenation, The NVCL organic monomers are dissolved in the detoxified solid waste leachate, and an inert gas is introduced to isolate oxygen. S2. In-situ induced prepolymerization Initiator is added and the temperature is controlled at 40~75℃ to start polymerization until the conversion rate of NVCL organic monomers reaches 20~60%, and a highly coordinated organic-inorganic long-chain intermediate is formed in the system. S3. Copolymerization hybridization In the S2 polymerization system, a composite natural polymer material package is introduced. By utilizing the continuous growth of active chain segments in the later stage of polymerization, organic long chains are generated and connected around the iron and aluminum ions and cellulose backbone. The cellulose phase is embedded into the growing polymer network through spatial connections to form an integrated backbone support structure. S4. Purification process, The S3 copolymerization and hybridization reaction continues until the conversion is complete. The residual monomers are removed by demolding or vacuum devolatilization to ensure that the residual NVCL is ≤0.05 wt%, thus obtaining the finished flocculant.
5. The method for preparing the in-situ copolymerized hybrid flocculant according to claim 4, characterized in that: The preparation steps of the composite natural polymer material package in S3 include the following: 1) Cellulose phase: Papermaking sludge is mechanically dewatered, washed and dissociated by water, and separated by hydrocyclone to obtain cellulose pulp; 2) Pectin phase: Citrus peel or apple pomace is extracted with acidified hot water and purified by membrane separation to obtain a pectin phase solution or pectin powder; 3) Plant tannin phase: Plant residues are extracted with hot water and then adsorbed and enriched with macroporous resin to obtain a tannin-rich eluent. Finally, the alcohol is removed under reduced pressure and the eluent is concentrated to a solid content of 5-30 wt%, so that the total tannin content is ≥40 wt%. 4) The three phases are compounded to form a natural polymer material package. The solid mass ratio of the three phases in the material package is set as cellulose: pectin: tannin = (1~20):(1~10):(0.5~8). The solid content of the material package is calibrated to 2~15 wt%. The natural polymer package mother liquor is prepared, or it is further dried to prepare powder. 5) Standardized quality control of natural polymer materials: the cellulose phase is controlled by ash content and fiber length distribution, the pectin phase is controlled by galacturonic acid content and solution viscosity, and the tannin phase is controlled by total tannin content and color / oxidative stability.
6. The method for preparing the in-situ copolymerized hybrid flocculant according to claim 4, characterized in that: The detoxification steps for the solid waste leachate in S1 are as follows: 1) Dealkali removal: Grind the iron-aluminum rich solid waste to D90≤150um, and then wash it with water to remove alkali, so that pH≤10; 2) Acid leaching: The solid waste after alkali removal is leached with the leaching medium, wherein the leaching temperature is 40~90℃ and the pH of the leaching solution is 0.5~25. After leaching, the solid and liquid are separated by pressure filtration or centrifugation to obtain crude leaching solution. 3) Fine purification: The crude leachate is subjected to sequential removal of anionic toxic substances and selective chelation adsorption of cationic toxic substances. The pH of the treatment is controlled at 2.0~5.
0. After the detoxification treatment, the total concentration of at least two heavy metal ions among As, Cr, Pb, Cd and Hg in the crude leachate is ≤1 mg / L.
7. The method for preparing the in-situ copolymerized hybrid flocculant according to claim 4, characterized in that: In S1, the NVCL organic monomer has a mass fraction of 5-35 wt% in the initial reaction system, and its 1-10 wt% aqueous solution has a viscosity of 0.2-20 Pa·s at 25°C. The organic long chain formed by the polymerization of the organic monomer serves as the bridging host.
8. The method for preparing the in-situ copolymerized hybrid flocculant according to claim 4, characterized in that: During the S3 copolymerization hybridization stage, the system pH was adjusted to 3.5–5.0, and the shear rate was controlled at 50–300 s⁻¹. -1 This promotes the coordination complexation between pectin, tannins and metal ions, as well as the spatial anchoring of cellulose.
9. The method for preparing the in-situ copolymerized hybrid flocculant according to claim 5, characterized in that: The cellulose phase consists of 0.1–20 wt%, with an ash content of ≤5 wt% and a median fiber length of 0.2–2.0 mm; the pectin phase consists of 0.1–10 wt%, and the viscosity of a 1 wt% pectin solution at 25°C is 10–300 mPa·s; the tannin phase consists of 0.05–8 wt%.
10. A method for applying the in-situ copolymerized hybrid flocculant according to claim 1, characterized in that: The steps for using the one-step conditioning method are as follows: 1) The hybrid flocculant is directly added to the sludge to be treated, with a dosage of 80~800 mg / L based on active solids; 2) Perform rapid mixing and slow mixing sequentially to form large-particle-size, high-strength shear-resistant flocs with a physical fibrous skeleton and a particle size of 0.5~8 mm. The G-value of the rapid mixing stage is 200~800s. -1 The G value during the slow mixing phase is 20~120s. -1 ; 3) Solid-liquid separation: The flocs after conditioning in step 2) are directly fed into plate and frame filter press, belt filter press, or centrifugal dewatering equipment.