Nanocomposite modified electroplating sludge powder and preparation method and application thereof

Abstract

This invention belongs to the field of building materials technology, specifically relating to a nanocomposite modified electroplating sludge powder, its preparation method, and its application. The preparation method of the nanocomposite modified electroplating sludge powder of this invention includes the following steps: (1) placing electroplating sludge water-quenched slag and nano-SiO2 particles in an airflow pulverizer, using airflow to carry the nano-SiO2 particle stream, causing the nano-SiO2 particle stream to collide with the electroplating sludge water-quenched slag, embedding the nano-SiO2 particles into the surface defects of the electroplating sludge water-quenched slag, obtaining an intermediate product; (2) placing the intermediate product in a fluidized bed reactor, heating it, and spraying a modifier solution onto the fluidized suspended intermediate product, causing the modifier solution to undergo in-situ sol-gel coupling on the surface of the intermediate product, obtaining the nanocomposite modified electroplating sludge powder. The nanocomposite modified electroplating sludge powder of this invention can achieve a superhydrophobic level.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a nanocomposite modified electroplating sludge micro powder, its preparation method, and its application. Background Technology

[0002] Water-quenched slag (WQS) from electroplating sludge is a glassy waste residue formed after electroplating sludge undergoes high-temperature melting and rapid water quenching. Due to the release of thermal stress during the rapid cooling process, its surface contains a large number of micron-sized shrinkage pores. Currently, the main application of WQS is as a cementitious admixture or concrete additive, but its irregular particle shape, smooth surface, and deep pits present many challenges in practical applications.

[0003] In existing technologies, silane coupling agents are often used for surface modification to improve the performance of WQS. However, this conventional modification has obvious drawbacks: First, silane coupling agents can only form a monolayer on the particle surface. Since the WQS surface is smooth and has deep pits, the simple organic layer is only connected to the matrix by weak hydrogen bonds or physical adsorption, resulting in poor adhesion. Under the strong shear forces during concrete mixing and service, it is easy to peel off, leading to hydrophobic failure. Second, according to the Wenzel model, achieving superhydrophobicity requires a micro-nano binary rough structure. However, WQS only has micron-level roughness and lacks nanoscale structure, making it difficult for conventional modification to achieve a high level of hydrophobicity. Moreover, the hydrophobicity will degrade over time.

[0004] Therefore, there is an urgent need to develop an electroplating sludge-based cementitious material that can construct a stable micro-nano rough structure, achieve superhydrophobicity, and possess excellent long-term hydrophobic retention capability, in order to solve the above-mentioned technical bottlenecks. Summary of the Invention

[0005] The purpose of this invention is to provide a nanocomposite modified electroplating sludge powder, its preparation method and application, so as to help solve or improve the problem of easy peeling or low hydrophobicity of the hydrophobic modified layer of electroplating sludge water quenching slag in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing nanocomposite modified electroplating sludge micro powder, comprising the following steps: (1) embedding of nano SiO2 particles: placing electroplating sludge water-quenched slag and nano SiO2 particles in an air jet mill, using airflow to carry nano SiO2 particle flow, causing the nano SiO2 particle flow to collide with the electroplating sludge water-quenched slag, embedding the nano SiO2 particles into the surface defects of the electroplating sludge water-quenched slag, and obtaining an intermediate product; (2) in-situ sol-gel coupling: placing the intermediate product in a fluidized bed reactor, heating, and spraying a modifier solution onto the fluidized suspension intermediate product, the modifier solution undergoing in-situ sol-gel coupling on the surface of the intermediate product, and obtaining the nanocomposite modified electroplating sludge micro powder; the components of the modifier solution include hydrophobic silane and crosslinking agent, the crosslinking agent being tetraethyl orthosilicate.

[0007] Preferably, the hydrophobic silane is hexadecyltrimethoxysilane and / or γ-methacryloyloxypropyltrimethoxysilane; the mass ratio of the hydrophobic silane to the crosslinking agent is (3-5):1.

[0008] Preferably, in step (1), the particle size of the nano-SiO2 is 20-50 nm.

[0009] Preferably, in step (1), the mass ratio of the electroplating sludge water-quenched slag to the nano SiO2 is 100:(1-3); the pressure of the airflow is 0.6-0.8MPa; and in step (1), the self-collision time between the nano SiO2 particle stream and the electroplating sludge water-quenched slag is 10-15min.

[0010] Preferably, in step (2), the temperature of the in-situ sol-gel coupling is 110-120℃ and the time is 15-30min.

[0011] The present invention also provides a nanocomposite modified electroplating sludge powder, which adopts the following technical solution: a nanocomposite modified electroplating sludge powder, wherein the nanocomposite modified electroplating sludge powder is prepared by the method described above.

[0012] The present invention also provides a cementing material, which adopts the following technical solution: a cementing material comprising the nano-composite modified electroplating sludge micro powder as described above.

[0013] The present invention also provides a concrete, which adopts the following technical solution: a concrete, wherein the concrete comprises cementitious material, standard sand, aggregate, water-reducing agent and water; the cementitious material comprises the nano-composite modified electroplating sludge micro powder as described above.

[0014] Preferably, the mass ratio of the cementitious material, standard sand, and aggregate is (400~500):(700~900):(1000~1200); by mass parts, the cementitious material comprises: 300-400 parts of ordinary Portland cement, 60-150 parts of nano-composite modified electroplating sludge powder, and 40-60 parts of fly ash; the mass ratio of the water-reducing agent to the ordinary Portland cement is (3-6):(300-400); and the mass ratio of water to the ordinary Portland cement is (160-200):(300-400).

[0015] The present invention also provides a concrete component, which adopts the following technical solution: a concrete component, wherein the concrete component is prepared by the concrete as described above, comprising the following steps: S1, dry mixing the cementitious material evenly, adding water and water-reducing agent, stirring to obtain a mixed slurry; S2, adding standard sand and aggregate to the mixed slurry, stirring evenly, pouring into a mold and vibrating, curing, thereby obtaining the concrete component.

[0016] Beneficial effects:

[0017] (1) In the preparation method of nanocomposite modified electroplating sludge micro powder of the present invention, hard nano SiO2 particles are creatively introduced. In the air jet mill, the huge kinetic energy generated by the air jet is used to force the nano SiO2 particles to be embedded in the surface defects of the electroplating sludge water quenching slag (the surface defects of the electroplating sludge water quenching slag include rapid cooling shrinkage cavities and high surface energy rough fracture surfaces generated by particle breakage during air jet milling). This not only fills the defects, but also creates artificial nano roughness on the smooth glass surface of the electroplating sludge water quenching slag, and constructs a micro-nano binary rough structure composed of micron-level electroplating sludge water quenching slag matrix and embedded nano-level SiO2 particle protrusions, thereby improving the hydrophobic effect.

[0018] (2) In the preparation method of the nanocomposite modified electroplating sludge powder of the present invention, by introducing a crosslinking agent (TEOS) and a hydrophobic silane, the inorganic SiO2 framework generated by the hydrolysis of TEOS firmly casts the SiO2 nanoparticles and the water-quenched sludge of electroplating sludge together, while the hydrophobic silane covers the outermost layer. This composite structure is extremely robust, which helps to solve the problem of easy peeling of the hydrophobic coating and achieves shear-resistant peeling.

[0019] (3) In the nanocomposite modified electroplating sludge powder of the present invention, since the nano SiO2 particles are embedded in the surface defects of the electroplating sludge water-quenched slag, when the hydrophobic layer on the particle surface is worn during use, more hydrophobic nano SiO2 particles will be exposed, continuing to provide hydrophobic function, realizing the self-repair effect of regeneration after the hydrophobic layer is worn, and greatly improving the hydrophobic durability of the material. The contact angle of the nanocomposite modified electroplating sludge powder of the present invention can reach more than 125°, reaching the superhydrophobic level.

[0020] (4) In the nanocomposite modified electroplating sludge powder of the present invention, the embedded SiO2 nanoparticles act as rigid protrusions and micro-nano spacers at the microscopic level. This protrusion structure, combined with the organic hydrophobic segments (organic hydrophobic segments of hydrophobic silanes) on the surface, transforms the originally high-resistance surface-to-surface contact between particles into low-resistance point-to-point contact. This allows the yield stress to be further reduced compared to conventional modification when the nanocomposite modified electroplating sludge powder of the present invention is applied to cementitious slurry or concrete slurry, thus improving the workability. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0022] The present invention will now be described in detail with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0023] This invention addresses the problem that the hydrophobic modification layer of electroplating sludge water-quenched slag is easily peeled off or has a low hydrophobicity level in the prior art, and provides a method for preparing nanocomposite modified electroplating sludge micro powder.

[0024] The preparation method of nanocomposite modified electroplating sludge powder according to the present invention includes the following steps: (1) embedding of nano SiO2 particles: placing electroplating sludge water quenching slag and nano SiO2 particles in an air jet mill, using airflow to carry nano SiO2 particle flow (generating particle shot peening effect) to make nano SiO2 particle flow collide with electroplating sludge water quenching slag, embedding nano SiO2 particles into the surface defects of electroplating sludge water quenching slag, and obtaining intermediate product; (2) in-situ sol-gel coupling: placing intermediate product in a fluidized bed reactor, spraying modifier solution onto intermediate product in fluidized suspension state, and in-situ sol-gel coupling of modifier solution on the surface of intermediate product to obtain nanocomposite modified electroplating sludge powder; the components of modifier solution include hydrophobic silane and crosslinking agent, and the crosslinking agent is tetraethyl orthosilicate.

[0025] Preferably, the fluidized bed reactor is equipped with a heating device (the setting of the heating device facilitates the adjustment of the temperature in the fluidized bed, so as to help achieve in-situ sol-gel coupling of the modifier solution on the surface of the intermediate product through temperature control) and / or a spraying device (the spraying device can be used to atomize the modifier solution).

[0026] More preferably, in step (2), an atomized modifier solution is sprayed onto the fluidized suspension intermediate product; in step (2), the intermediate product can be fluidized suspension by hot air flow.

[0027] In the preparation method of the nanocomposite modified electroplating sludge micro powder of the present invention, in step (1), hard nano-SiO2 particles are creatively introduced. In an air jet mill, the huge kinetic energy generated by the airflow is used to force the nano-SiO2 particles to be embedded in the surface defects of the electroplating sludge water-quenched slag (the surface defects of the electroplating sludge water-quenched slag include rapid cooling shrinkage cavities and high surface energy rough fracture surfaces generated by particle breakage during air jet milling). This not only fills the defects, but also creates artificial nano-roughness on the smooth glassy surface of the electroplating sludge water-quenched slag, constructing a micro-nano binary rough structure composed of a micron-level electroplating sludge water-quenched slag matrix and embedded nano-level SiO2 particle protrusions, thereby increasing the contact angle and achieving a superhydrophobic level. In step (2), by introducing a crosslinking agent (TEOS) and a hydrophobic silane compound, the inorganic SiO2 skeleton generated by TEOS hydrolysis firmly casts the SiO2 nanoparticles and the electroplating sludge water-quenched slag together, while the hydrophobic silane covers the outermost layer. This composite structure is extremely robust, which helps to solve the problem of easy peeling of hydrophobic coatings and achieves shear-resistant peeling of hydrophobic coatings.

[0028] Furthermore, since the nano-SiO2 particles are deeply embedded inside the pores, when the hydrophobic layer on the surface of the nanocomposite modified electroplating sludge powder is worn away during use, the deep hydrophobic nanoparticles will be exposed and continue to provide hydrophobic function, achieving a self-repairing effect after wear and significantly improving the hydrophobic durability of the material.

[0029] In a preferred embodiment of the preparation method of the nanocomposite modified electroplating sludge powder of the present invention, the hydrophobic silane is hexadecyltrimethoxysilane and / or γ-methacryloyloxypropyltrimethoxysilane; the mass ratio of hydrophobic silane to crosslinking agent is (3-5):1 (e.g., 3:1, 3.5:1, 4:1, 4.5:1 or 5:1). If the amount of hydrophobic silane is too high and the amount of crosslinking agent (TEOS) is too low, the bonding force between the hydrophobic modified layer formed by sol-gel coupling and the intermediate product will decrease, and the hydrophobic modified layer formed by sol-gel coupling will be easily peeled off. If the amount of hydrophobic silane is too low and the amount of crosslinking agent (TEOS) is too high, the hydrophobicity of the hydrophobic modified layer formed by sol-gel coupling will be insufficient, and when the nanocomposite modified electroplating sludge powder of the present invention is applied to cementitious materials or concrete, the effect on improving the rheological properties of the cementitious material slurry or concrete slurry will be poor.

[0030] In a preferred embodiment of the preparation method of nanocomposite modified electroplating sludge powder of the present invention, in step (1), the particle size of nano SiO2 is 20-50 nm.

[0031] In a preferred embodiment of the method for preparing nanocomposite modified electroplating sludge powder of the present invention, the mass ratio of electroplating sludge water-quenched slag to nano-SiO2 is 100:(1-3) (e.g., 100:1, 100:1.5, 100:2, 100:2.5, 100:3); the airflow pressure is 0.6-0.8 MPa (e.g., 0.6 MPa, 0.65 MPa, 0.7 MPa, 0.75 MPa or 0.8 MPa); step (1) is carried out in an air jet mill, and in step (1), the self-collision time between the nano-SiO2 particle stream and the electroplating sludge water-quenched slag is 10-15 min (e.g., 10 min, 11 min, 12 min, 13 min, 14 min or 15 min). In the air jet mill, the electroplating sludge water-quenched slag and nano-SiO2 self-collide under the airflow, so that the nano-SiO2 embeds into the surface defects of the electroplating sludge water-quenched slag. If the proportion of nano-SiO2 particles is too small, the number of nano-SiO2 particles will be insufficient to fill the defects (microcracks and shrinkage cavities) on the surface of the electroplating sludge quenching slag particles, failing to form a dense packing structure. This results in a lack of significant improvement in the density of the modified nanocomposite electroplating sludge powder. If the proportion of nano-SiO2 particles is too large, the excess nano-SiO2 particles are prone to self-aggregation, forming large soft agglomerates instead of being dispersed and embedded in the surface defects of the electroplating sludge quenching slag. If the airflow pressure is too low, the kinetic energy is insufficient, and the nano-SiO2 particles can only adhere to the surface, failing to embed in the surface defects of the electroplating sludge quenching slag. This results in weak bonding and easy detachment during subsequent stirring. If the airflow pressure is too high, the excessive impact force may damage the pore structure of the electroplating sludge quenching slag surface, causing the nano-SiO2 particles to lose their carrier. If the self-collision treatment time is too short, some electroplating sludge quenching slag particles will not have effectively collided with nano-SiO2 particles, resulting in poor product uniformity; if the self-collision treatment time is too long, prolonged friction and collision may lead to local temperature rise, causing changes in the surface properties of the material.

[0032] In a preferred embodiment of the preparation method of the nanocomposite modified electroplating sludge powder of the present invention, in step (2), the in-situ sol-gel coupling temperature is 110-120℃ and the time is 15-30min (e.g., 15min, 20min, 25min or 30min). If the in-situ sol-gel coupling temperature is too low, the moisture cannot evaporate completely, resulting in the nano-SiO2 particles and the electroplating sludge water-quenched slag particles mainly relying on weak physical adsorption bonding, making it difficult to transform into a strong chemical bond. If the in-situ sol-gel coupling temperature is too high, the nano-SiO2 particles are prone to agglomeration at high temperatures, forming hard agglomerates that are difficult to disperse, leading to coarser powder particle size and decreased activity. If the reaction time is too short, the reaction will not proceed completely, and the nano-SiO2 particles will only be physically deposited on the surface. In subsequent use, the hydrophobic modified layer formed by in-situ sol-gel coupling is prone to falling off. If the reaction time is too long and the heating is prolonged, the nano-SiO2 particles will undergo excessive dehydration, forming hard agglomerates that cannot be redispersed during subsequent stirring. This may create stress concentration points inside the material, reducing the strength of the final product.

[0033] This invention also proposes a nanocomposite modified electroplating sludge powder, which is prepared by the method described above in the embodiments of this invention.

[0034] The nanocomposite modified electroplating sludge powder of the present invention comprises: a matrix, a pinned phase, and a bridging phase; the matrix is ​​electroplating sludge water-quenched slag; the pinned phase is nano-SiO2 particles pinned to surface defects of the electroplating sludge water-quenched slag; the bridging phase is an organosiloxane network film encapsulating the matrix and the pinned phase (the bridging phase simultaneously encapsulates the matrix and the pinned phase through chemical bonds; the bridging phase is formed by in-situ sol-gel coupling of the modifier solution on the surface of the intermediate product).

[0035] The present invention also proposes a gelling material, wherein the gelling material in the embodiments of the present invention includes the nanocomposite modified electroplating sludge micro powder as described above.

[0036] In a preferred embodiment of the cementitious material of the present invention, the cementitious material comprises the following components in parts by weight: 300-400 parts of ordinary silicate cement (e.g., 300 parts, 320 parts, 340 parts, 360 parts, 380 parts or 400 parts), 60-150 parts of nano-composite modified electroplating sludge powder (e.g., 60 parts, 80 parts, 100 parts, 130 parts or 150 parts), and 40-60 parts of fly ash (e.g., 40 parts, 45 parts, 50 parts, 55 parts or 60 parts).

[0037] The present invention also proposes a type of concrete, wherein the concrete of the present invention comprises cementitious materials, water-reducing agents, water, standard sand and aggregates; the cementitious materials comprise the nano-composite modified electroplating sludge powder as described above.

[0038] In a preferred embodiment of the concrete of the present invention, the mass ratio of cementitious material, standard sand, and aggregate is (400-500):(700-900):(1000-1200) (e.g., 400:700:1000, 400:800:1050, 400:900:1100, 450:700:1050, 450:800:1000, 450:800:1200, 500:700:1000, 500:800:1100, or 500:900:1200). The cementitious material, by mass parts, comprises: 300-400 parts of ordinary Portland cement (e.g., 300 parts, 320 parts, 340 parts, 360 parts, 380 parts, or 400 parts), and 60-150 parts of nano-composite modified electroplating sludge powder. (e.g., 60 parts, 80 parts, 100 parts, 130 parts, or 150 parts) and 40-60 parts fly ash (e.g., 40 parts, 45 parts, 50 parts, 55 parts, or 60 parts); the mass ratio of water-reducing agent to ordinary Portland cement is (3-6):(300-400) (e.g., 3:300, 3:350, 3:400, 4.5:300, 4.5:350, 4.5). :400, 6:300, 6:350 or 6:400); the mass ratio of water to ordinary Portland cement is (160-200):(300-400) (e.g., 160:300, 160:350, 160:400, 180:300, 180:350, 180:400, 200:300, 200:350 or 200:400).

[0039] This invention also proposes a concrete component. The concrete component of this embodiment is prepared using the concrete method described above, comprising the following steps: S1, dry mixing a cementitious material (the cementitious material may consist of nano-composite modified electroplating sludge powder, cement, and fly ash), adding water and a water-reducing agent, and stirring to obtain a mixed slurry; S2, adding standard sand and aggregate to the mixed slurry obtained in step S1, stirring evenly, pouring into a mold, vibrating, and curing. In step S1, the nano-composite modified electroplating sludge powder helps reduce the slurry viscosity (by utilizing the micro-aggregate filling effect of the nano-composite modified electroplating sludge powder to displace free water in the interparticle gaps); in step S2, during curing, the nano-composite modified electroplating sludge powder utilizes its micro-aggregate filling effect and pozzolanic activity to promote the growth of hydration products, physically blocking the interconnected pores inside the concrete, thereby improving impermeability.

[0040] The present invention provides a detailed description of the nanocomposite modified electroplating sludge powder, its preparation method, and its application through specific embodiments.

[0041] The sources of the main raw materials used in the following examples:

[0042] Electroplating sludge water quenching slag: water quenching slag taken from the smelting workshop of Ningbo Dadi Chemical Environmental Protection Co., Ltd., dried at 105℃ and pre-crushed to a particle size of <2mm;

[0043] Nano-SiO2: Particle size 7-20nm, specific surface area 200±25m² 2 / g, hydrophilic fumed silica;

[0044] The aggregate is continuously graded crushed stone with a particle size of 5-25mm; the standard sand is medium sand with a fineness modulus of 2.6-3.0.

[0045] Example 1

[0046] The preparation method of the nanocomposite modified electroplating sludge powder in this embodiment includes the following steps:

[0047] (1) Embedding of nano-SiO2 particles: Select electroplating sludge water-quenched slag with a particle size of 0.15-2mm. Mix 1000g of electroplating sludge water-quenched slag with 20g of nano-SiO2 (mix evenly according to the ratio); place the mixture in a fluidized bed air jet mill, adjust the air pressure to 0.7MPa, and perform self-collision circulation treatment for 10min. Utilize the particle shot peening effect of high-pressure jet (0.7MPa airflow) to embed nano-SiO2 particles into the surface defects of the electroplating sludge water-quenched slag (wherein, surface defects mainly refer to shrinkage cavities formed by the rapid cooling process of the electroplating sludge water-quenched slag; and also include high surface energy rough fracture surfaces generated by particle breakage during air jet milling), to obtain intermediate products; wherein, during the operation of the air jet mill, the electroplating sludge water-quenched slag will undergo severe ultra-fine grinding (during the air jet milling process, the electroplating sludge water-quenched slag with a particle size of 0.15-2mm will be ground into micron-level powder with a D50 of about 8.6μm; the nano-SiO2 will mainly undergo deagglomeration and will not destroy the original particles).

[0048] (2) In-situ sol-gel coupling: Preparation of modification solution: 95g ethanol, 4g hexadecyltrimethoxysilane (component A) and 1g tetraethyl orthosilicate (TEOS, component B) are mixed evenly to obtain a modifier solution; in a fluidized bed reactor equipped with heating and spraying devices, the intermediate product is in a fluidized suspension state at 115℃, and the modifier solution is sprayed in the form of atomization using a pneumatic atomizing nozzle (droplet size is 10-50μm). The modifier solution undergoes in-situ sol-gel coupling on the surface of the intermediate product (the solvent evaporation of the modifier solution at 115℃ induces the sol-gel transition; reaction time is 20min). The modifier solution solidifies into a film to obtain the nano-composite modified electroplating sludge micro powder of this embodiment.

[0049] By weight, the cementing material in this embodiment includes: 80 parts of nano-composite modified electroplating sludge powder, 320 parts of ordinary silicate cement, and 40 parts of fly ash.

[0050] The concrete in this embodiment, by weight, includes: 80 parts of nano-composite modified electroplating sludge powder, 320 parts of ordinary silicate cement, 40 parts of fly ash, 4.4 parts of polycarboxylate superplasticizer, 175 parts of water, 760 parts of medium sand (standard sand) with a fineness modulus of 2.6-3.0, and 1080 parts of continuously graded crushed stone (aggregate) with a particle size of 5-25mm.

[0051] The concrete component in this embodiment is prepared using the concrete as described above, and includes the following steps:

[0052] S1. Mix ordinary silicate cement, nano-composite modified electroplating sludge powder, fly ash, water and polycarboxylate superplasticizer in a forced mixer for 180 seconds to obtain a mixed slurry.

[0053] S2. Add standard sand and aggregate to the mixed slurry, stir evenly, and pour into a 150mm×150mm×150mm mold. Compact the mixture using a vibrating table and cure for 28 days to obtain the concrete component of this embodiment.

[0054] Example 2

[0055] The preparation method of the nanocomposite modified electroplating sludge powder in this embodiment includes the following steps:

[0056] (1) Embedding of nano-SiO2 particles: 1000g of electroplating sludge water quenching slag (particle size of 0.15-2mm) is mixed with 20g of nano-SiO2 (mixed evenly according to the ratio); the mixture is placed in a fluidized bed air jet mill, the air pressure is adjusted to 0.8MPa, and self-collision circulation treatment is carried out for 15min. The nano-SiO2 particles are embedded in the surface defects of the electroplating sludge water quenching slag by utilizing the particle shot peening effect of the airflow to obtain the intermediate product;

[0057] (2) In-situ sol-gel coupling: First, 95g of ethanol, 5g of γ-methacryloxypropyltrimethoxysilane (KH-570, component A) and 1g of tetraethyl orthosilicate (TEOS, component B) are mixed evenly to obtain a modifier solution; then, in a fluidized bed reactor equipped with heating and spraying devices, the intermediate product is kept in a fluidized suspension state at 120℃, and the modifier solution is sprayed in the form of atomization using a pneumatic atomizing nozzle (droplet size is 10-50μm). The modifier solution undergoes in-situ sol-gel coupling on the surface of the intermediate product (the solvent evaporation of the modifier solution at 120℃ induces the sol-gel transformation; reaction time is 20min). The modifier solution solidifies into a film to obtain the nano-composite modified electroplating sludge micro powder of this embodiment.

[0058] By weight, the cementing material in this embodiment includes: 70 parts of nano-composite modified electroplating sludge powder, 380 parts of ordinary silicate cement, and 40 parts of fly ash.

[0059] The concrete in this embodiment, by weight, includes: 70 parts of nano-composite modified electroplating sludge powder, 380 parts of ordinary silicate cement, 40 parts of fly ash, 4.9 parts of polycarboxylate superplasticizer, 190 parts of water, 720 parts of medium sand (standard sand) with a fineness modulus of 2.6-3.0, and 1000 parts of continuously graded crushed stone (aggregate) with a particle size of 5-25mm.

[0060] The concrete component in this embodiment is prepared using the concrete as described above, and includes the following steps:

[0061] S1. Mix ordinary silicate cement, nano-composite modified electroplating sludge powder, fly ash, water and polycarboxylate superplasticizer in a forced mixer for 180 seconds to obtain a mixture.

[0062] S2. Add standard sand and aggregate to the mixture, stir evenly, and pour into a 150mm×150mm×150mm mold. Compact the mixture with a vibrating table and cure for 28 days to obtain the concrete component of this embodiment.

[0063] Example 3

[0064] The preparation method of the nanocomposite modified electroplating sludge powder in this embodiment includes the following steps:

[0065] (1) Embedding of nano-SiO2 particles: 1000g of electroplating sludge water quenching slag (particle size of 0.15-2mm) is mixed with 30g of nano-SiO2 (mixed evenly according to the ratio); the mixture is placed in a fluidized bed air jet mill, the air pressure is adjusted to 0.75MPa, and self-collision circulation treatment is carried out for 12min. The particle shot peening effect of high pressure jet (0.75MPa air flow) is used to embed nano-SiO2 particles into the surface defects of electroplating sludge water quenching slag to obtain intermediate product;

[0066] (2) In-situ sol-gel coupling: Preparation of modifier solution: 95g ethanol, 4g hexadecyltrimethoxysilane (component A) and 1g tetraethyl orthosilicate (TEOS, component B) are mixed evenly to obtain modifier solution; in a fluidized bed reactor equipped with heating and spraying devices, the intermediate product is in a fluidized suspension state at 115℃, and the modifier solution is sprayed in the form of atomization using a pneumatic atomizing nozzle (droplet size is 10-50μm). In-situ sol-gel coupling occurs on the surface of the intermediate product using the modifier solution (the solvent evaporation of the modifier solution at 115℃ induces the sol-gel transition; reaction time is 20min). The modifier solution solidifies into a film to obtain the nano-composite modified electroplating sludge micro powder of this embodiment.

[0067] The cementitious materials and concrete in this embodiment are identical to those in Example 1, except that the nano-composite modified electroplating sludge powder used in this embodiment is different from that in Example 1 (the nano-composite modified electroplating sludge powder used in this embodiment is used instead of the nano-composite modified electroplating sludge powder used in Example 1).

[0068] Example 4

[0069] The only difference between the nanocomposite modified electroplating sludge powder in this embodiment and that in Example 1 is that in step (2), octadecyltrimethoxysilane (long carbon chain, stronger hydrophobicity) is used instead of hexadecyltrimethoxysilane (component A) in Example 1; the rest are consistent with Example 1.

[0070] The cementitious materials and concrete in this embodiment are identical to those in Example 1, except that the nano-composite modified electroplating sludge powder used in this embodiment is different from that in Example 1 (the nano-composite modified electroplating sludge powder used in this embodiment is used instead of the nano-composite modified electroplating sludge powder used in Example 1).

[0071] Example 5

[0072] The preparation method of the nanocomposite modified electroplating sludge powder in this embodiment includes the following steps:

[0073] (1) Embedding of nano-SiO2 particles: Select electroplating sludge water-quenched slag with a particle size of 0.15-2mm. Mix 1000g of electroplating sludge water-quenched slag with 10g of nano-SiO2 (mix evenly according to the ratio); place the mixture in a fluidized bed air jet mill, adjust the air pressure to 0.6MPa, and perform self-collision circulation treatment for 10min. Utilize the particle shot peening effect of high-pressure jet (0.6MPa airflow) to embed nano-SiO2 particles into the surface defects of the electroplating sludge water-quenched slag to obtain intermediate products.

[0074] (2) In-situ sol-gel coupling: Preparation of modification solution: Mix 95g ethanol, 3g hexadecyltrimethoxysilane (component A) and 1g tetraethyl orthosilicate (TEOS, component B) evenly; In a fluidized bed reactor equipped with heating and spraying devices, the intermediate product is in a fluidized suspension state at 110℃, and the modifier solution is sprayed into the intermediate product in the form of atomization using a pneumatic atomizing nozzle (droplet size 10-50μm). The modifier solution undergoes in-situ sol-gel coupling on the surface of the intermediate product (the solvent evaporation of the modifier solution at 110℃ induces the sol-gel transformation, and the reaction lasts for 20min). The modifier solution solidifies into a film to obtain the nano-composite modified electroplating sludge micro powder of this embodiment.

[0075] The cementitious material in this embodiment, by mass parts, includes: 60 parts of nano-composite modified electroplating sludge powder, 340 parts of ordinary silicate cement, and 40 parts of fly ash.

[0076] The concrete in this embodiment, by weight, includes: 440 parts of the above-mentioned cementitious material (specific components as above), 4.2 parts of polycarboxylate superplasticizer, 170 parts of water, 750 parts of medium sand (standard sand) with a fineness modulus of 2.6-3.0, and 1100 parts of continuously graded crushed stone (aggregate) with a particle size of 5-25mm.

[0077] The preparation steps are the same as in Example 1.

[0078] Example 6

[0079] The preparation method of the nanocomposite modified electroplating sludge powder in this embodiment includes the following steps:

[0080] (1) Embedding of nano-SiO2 particles: Select electroplating sludge water-quenched slag with a particle size of 0.15-2mm. Mix 1000g of electroplating sludge water-quenched slag with 30g of nano-SiO2 (mix evenly according to the ratio); the nano-SiO2 particle size selected here is 40-50nm; place the mixture in a fluidized bed air jet mill, adjust the air pressure to 0.8MPa, and perform self-collision circulation treatment for 15min. Utilize the particle shot peening effect of the airflow to embed nano-SiO2 particles into the surface defects of the electroplating sludge water-quenched slag to obtain an intermediate product.

[0081] (2) In-situ sol-gel coupling: Preparation of modification solution: 95g ethanol, 5g γ-methacryloxypropyltrimethoxysilane (KH-570, component A) and 1g tetraethyl orthosilicate (TEOS, component B) are mixed evenly; in a fluidized bed reactor equipped with heating and spraying devices, the intermediate product is in a fluidized suspension state at 120℃, and the modifier solution is sprayed in the form of atomization using a pneumatic atomizing nozzle (droplet size is 10-50μm). The modifier solution undergoes in-situ sol-gel coupling on the surface of the intermediate product (the solvent evaporation of the modifier solution at 115℃ induces the sol-gel transition; reaction time is 20min). The modifier solution solidifies into a film to obtain the nano-composite modified electroplating sludge micro powder of this embodiment.

[0082] The cementitious material in this embodiment, by weight, includes: 100 parts of nano-composite modified electroplating sludge powder, 300 parts of ordinary silicate cement, and 50 parts of fly ash.

[0083] The concrete in this embodiment, by weight, includes: 450 parts of the above-mentioned cementitious material, 4.5 parts of polycarboxylate superplasticizer, 180 parts of water, 780 parts of medium sand with a fineness modulus of 2.6-3.0, and 1050 parts of continuously graded crushed stone with a particle size of 5-25mm.

[0084] The preparation steps are the same as in Example 1.

[0085] Example 7

[0086] The preparation method of the nanocomposite modified electroplating sludge powder in this embodiment includes the following steps:

[0087] (1) Embedding of nano-SiO2 particles: The raw materials and processes are the same as in Example 1.

[0088] (2) In-situ sol-gel coupling: Preparation of modification solution: 95g ethanol, 2g hexadecyltrimethoxysilane, 2g γ-methacryloxypropyltrimethoxysilane (the two are mixed as component A, total amount 4g) and 1g tetraethyl orthosilicate (TEOS, component B) are mixed evenly; in a fluidized bed reactor equipped with heating and spraying devices, the intermediate product is in a fluidized suspension state at 115℃, and the modifier solution is sprayed in the form of atomization using a pneumatic atomizing nozzle (droplet size 10-50μm). The modifier solution undergoes in-situ sol-gel coupling on the surface of the intermediate product (the solvent evaporation of the modifier solution at 110℃ induces the sol-gel transformation, and the reaction takes 20min). The modifier solution solidifies into a film to obtain the nano-composite modified electroplating sludge micro powder of this embodiment.

[0089] The cementitious materials and concrete in this embodiment are identical to those in Example 1, except that the nano-composite modified electroplating sludge powder used in this embodiment is different from that in Example 1 (the nano-composite modified electroplating sludge powder used in this embodiment is used instead of the nano-composite modified electroplating sludge powder used in Example 1).

[0090] Comparative Example 1

[0091] The only difference between this comparative example and Example 1 is that only KH-570 was used for ordinary spray modification of electroplating sludge water-quenched slag; the specific experimental steps are as follows:

[0092] (1) Place 1000g of electroplating sludge water quenching slag (particle size 0.15-2mm) in a planetary ball mill, without adding nano SiO2, and perform dry ball milling for 30min until the median particle size (D50) of the powder is about 8-10μm (equivalent to the particle size of the intermediate product in Example 1), and obtain ordinary electroplating sludge water quenching slag micro powder.

[0093] (2) Dissolve 5g of γ-methacryloxypropyltrimethoxysilane (KH-570) in 95g of ethanol and stir until homogeneous to obtain a modified solution; place the above ordinary electroplating sludge water quenching slag micro powder in a high-speed mixer, and spray the modified solution into the mixer in the form of a spray at a stirring speed of 500r / min, and mix for 10min; take out the powder and dry it in an oven at 110℃ for 20min to remove the solvent and obtain the modified micro powder of Comparative Example 1.

[0094] The preparation of the cementitious materials and concrete in this comparative example: the proportions and preparation steps are the same as in Example 1.

[0095] Comparative Example 2

[0096] The only difference between this comparative example and Example 1 is that, in step (1), although nano-SiO2 particles were added, the high-pressure jet implantation process was not used. Instead, the nanoparticles were simply mechanically mixed with the electroplating sludge water-quenched micro powder and then sprayed with a modifier solution. The specific experimental steps are as follows:

[0097] (1) Place 1000g of electroplating sludge water quenching slag (particle size 0.15-2mm) in a ball mill for grinding until the median particle size (D50) of the powder is about 8-10μm to obtain electroplating sludge micro powder; then, add 20g of nano SiO2 to the above electroplating sludge micro powder, place it in a common mechanical mixer, and mix for 10min under normal temperature, normal pressure and low speed stirring (300r / min) to disperse the nano SiO2 particles between the electroplating sludge micro powder to obtain a physical mixture;

[0098] (2) The above physical mixture was placed in a fluidized bed reactor and in-situ sol-gel coupling was performed under the conditions of Example 1 to obtain the modified micro powder of Comparative Example 2.

[0099] The preparation of the cementitious materials and concrete in this comparative example: the proportions and preparation steps are the same as in Example 1.

[0100] Comparative Example 3

[0101] The only difference between this comparative example and Example 1 is that micron-sized SiO2 powder (average particle size 2μm) is used instead of nano-sized SiO2 (30nm) in Example 1; all other aspects are the same as in Example 1.

[0102] Comparative Example 4

[0103] The only difference between this comparative example and Example 1 is that a wet ball milling process is used instead of "high-pressure jet implantation". Electroplating sludge water-quenched residue, nano-SiO2, and ethanol are placed in a ball mill and wet-milled for 30 minutes, then dried and sprayed with a modifier solution identical to that in Example 1; the specific experimental steps are as follows:

[0104] The preparation method of the electroplating sludge powder in this comparative example:

[0105] (1) Select electroplating sludge water quenching residue with a particle size of 0.15-2mm. Mix 1000g of electroplating sludge water quenching residue, 20g of nano SiO2 and 600g of anhydrous ethanol and load them into the jar of a planetary ball mill; add 4000g of zirconia grinding balls (ball-to-material ratio of 4:1, grinding balls are of mixed gradation of Φ5mm and Φ10mm), and perform wet ball milling at a speed of 350r / min for 30min to grind the water quenching residue to the micron level (D50 about 8-10μm).

[0106] (2) Take out the slurry after ball milling, filter out the grinding balls with a 100-mesh sieve, place the slurry in an oven at 105°C to dry to constant weight, and break it apart to obtain dry micro powder; then, place the dry micro powder in a fluidized bed reactor equipped with heating and spraying devices, and carry out in-situ sol-gel coupling completely according to the process parameters of Example 1: under fluidized conditions at 115°C, use a pneumatic atomizing nozzle to spray the modified liquid with the same components as in Example 1 in the form of atomization, react for 20 minutes, and solidify into a film.

[0107] The preparation of the cementitious materials and concrete in this comparative example: the proportions and preparation steps are the same as in Example 1.

[0108] Comparative Example 5

[0109] The only difference between this comparative example and Example 1 is that component B (tetraethyl orthosilicate TEOS) is not added to the modified solution, and only component A (hexadecyltrimethoxysilane) is used; all other aspects are the same as in Example 1.

[0110] The specific steps are as follows:

[0111] The preparation method of the modified electroplating sludge powder in this comparative example includes the following steps:

[0112] (1) Embedding of nano-SiO2 particles: Select electroplating sludge water-quenched slag with a particle size of 0.15-2mm. Mix 1000g of electroplating sludge water-quenched slag with 20g of nano-SiO2 (mix evenly according to the ratio); place the mixture in a fluidized bed air jet mill, adjust the air pressure to 0.7MPa, and perform self-collision circulation treatment for 10min. Utilize the particle shot peening effect of the air jet to embed nano-SiO2 particles into the surface defects of the electroplating sludge water-quenched slag (wherein, surface defects mainly refer to shrinkage cavities formed by the rapid cooling process of the electroplating sludge water-quenched slag; and also include high surface energy rough fracture surfaces generated by particle breakage during the air jet milling process), to obtain intermediate products; wherein, during the operation of the air jet mill, the electroplating sludge water-quenched slag will undergo severe ultra-fine grinding (during the air jet milling process, the electroplating sludge water-quenched slag with a particle size of 0.15-2mm will be ground into micron-level powder with a D50 of about 8.6μm; the nano-SiO2 will mainly undergo deagglomeration and will not destroy the original particles).

[0113] (2) In-situ sol-gel coupling: Preparation of modified solution: 95g ethanol and 4g hexadecyltrimethoxysilane (component A) were mixed evenly to obtain modified solution; in a fluidized bed reactor equipped with heating and spraying devices, the intermediate product was kept in a fluidized suspension state at 115℃, and the modified solution was sprayed in the form of atomization using a pneumatic atomizing nozzle (droplet size was 10-50μm). In-situ sol-gel coupling occurred on the surface of the intermediate product (the solvent evaporation of the modified solution at 115℃ induced the sol-gel transformation; the reaction time was 20min). The modified solution solidified into a film to obtain the modified electroplating sludge micro powder of this comparative example.

[0114] The cementitious materials and concrete in this comparative example are the same as those in Example 1, with the same mix proportions and preparation steps.

[0115] Experimental Example

[0116] Hydrophobicity, abrasion resistance, rheology, and durability were tested.

[0117] 1. Hydrophobicity: Take a standard concrete test block that has been cured for 28 days, cut it to expose the fresh central cut surface. Use 200-grit diamond sandpaper to grind the cut surface back and forth 50 times to simulate surface abrasion, removing the laitance and particle skin from the cut surface, and blow away the dust with an air gun. Use a contact angle meter to test the water contact angle of the worn cut surface.

[0118] 2. Rheological properties: The yield stress of the cementitious slurry (a cementitious slurry obtained by mixing cement, nano-composite modified electroplating sludge powder, fly ash, polycarboxylate superplasticizer and water) is tested.

[0119] 3. Durability: The 28-day water absorption rate and chloride ion migration coefficient (RCM method) of concrete are tested according to GB / T 50082 standard to evaluate its impermeability.

[0120] The test results are shown in Table 1 below:

[0121] Table 1 Performance Test Results

[0122]

[0123] As shown in Table 1:

[0124] The concrete prepared from the nanocomposite modified electroplating sludge powder in Examples 1-7 all achieved an initial contact angle of over 125° on the cross-section, significantly higher than the 105.3° of the conventionally sprayed modified concrete in Comparative Example 1. This indicates that chemical grafting with organosilanes alone cannot overcome the hydrophilic defects on the matrix surface; it is necessary to introduce nano-SiO2 particles to construct a stable micro-nano binary rough structure in order to overcome the hydrophobic bottleneck and achieve a superhydrophobic effect.

[0125] After 50 cycles of reciprocating grinding on the concrete surface, the contact angles of Comparative Examples 1 and 2 plummeted to 48.6° and 88.2°, respectively, indicating that the hydrophobic coating on the surface had been removed, exposing the internal hydrophilic matrix. Conversely, after undergoing severe wear, the contact angles of Examples 1-7 remained firmly above 112°. This strongly demonstrates that the nano-SiO2 particle embedding process of this invention successfully achieved the physical pinning of nano-SiO2 particles at the surface defects of electroplating sludge water-quenched slag. Even if the concrete surface or the outer shell of the micro-particles is worn away, the hydrophobic SiO2 nanoparticles deeply embedded inside the surface defects (cavities) are immediately exposed, forming a second hydrophobic defense line and endowing the material with excellent overall hydrophobic properties.

[0126] The initial and post-wear contact angles of Comparative Example 3 were 108.8° and 65.4°, respectively, both significantly lower than those of the Example. This confirms that micron-sized particles, due to their excessive size, cannot penetrate the surface defects of electroplating sludge quenching slag; they can only float on the surface and cannot form an embedded structure, thus failing upon wear.

[0127] Comparative Example 4 showed that the contact angle decreased to 75.3° after wear. This indicates that in a wet environment, the buffering effect of the liquid consumes kinetic energy, resulting in the nano-SiO2 particles failing to acquire sufficient impact force to embed into the surface defects of the electroplating sludge quenched slag, and only exhibiting a physical adsorption state. This, in turn, proves the necessity of the present invention's process of embedding nano-SiO2 particles into the surface defects of the electroplating sludge quenched slag in an air jet mill.

[0128] Comparative Example 5 showed a contact angle as low as 58.6° after wear. This demonstrates that without the crosslinking agent (TEOS) component, the hydrophobic silane cannot resist shear spalling.

[0129] With the same amount of nano-SiO2 particles, the contact angle after wear in Example 2 was 121.5°, which was better than 118.2° in Example 1. This demonstrates that high kinetic energy is key to achieving the embedding of nano-SiO2 particles, and higher pressure means that the nano-SiO2 particles are implanted deeper and the mechanical interlocking is stronger.

[0130] The contact angle was further improved when the doping content of nano-SiO2 particles was increased or when long-chain silanes were used. This indicates that appropriately increasing the density of nano-SiO2 particles or the length of the hydrophobic chains helps to enhance the micro-roughness of the surface. Those skilled in the art can flexibly adjust within the scope of this invention according to actual engineering needs.

[0131] The yield stress of the slurry in all embodiments was significantly lower than that in the comparative example. This confirms that the nano-SiO2 particles embedded in the surface exert a nano-ball bearing effect, transforming the high-resistance sliding friction between particles into low-resistance rolling friction, thus significantly improving flow properties. Furthermore, the extremely low water absorption and chloride ion migration coefficient of the embodiment group further confirm the effective blocking of internal pores in concrete by the micro / nano structure, enhancing the long-term durability of the concrete structure.

[0132] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing nanocomposite modified electroplating sludge powder, characterized in that, Includes the following steps: (1) Embedding of nano-SiO2 particles: Placing electroplating sludge water-quenched slag and nano-SiO2 particles in an air jet mill, using air jet to carry nano-SiO2 particle flow, causing the nano-SiO2 particle flow to collide with the electroplating sludge water-quenched slag, embedding the nano-SiO2 particles into the surface defects of the electroplating sludge water-quenched slag, and obtaining intermediate products. (2) In-situ sol-gel coupling: The intermediate product is placed in a fluidized bed reactor, heated, and a modifier solution is sprayed onto the fluidized and suspended intermediate product. The modifier solution undergoes in-situ sol-gel coupling on the surface of the intermediate product to obtain the nano-composite modified electroplating sludge powder. The modifier solution comprises hydrophobic silane and a crosslinking agent, wherein the crosslinking agent is tetraethyl orthosilicate.

2. The method for preparing nanocomposite modified electroplating sludge powder as described in claim 1, characterized in that, The hydrophobic silane is hexadecyltrimethoxysilane and / or γ-methacryloxypropyltrimethoxysilane; The mass ratio of the hydrophobic silane to the crosslinking agent is (3-5):

1.

3. The method for preparing nanocomposite modified electroplating sludge powder as described in claim 1, characterized in that, In step (1), the particle size of the nano-SiO2 is 20-50 nm.

4. The method for preparing nanocomposite modified electroplating sludge powder as described in claim 1, characterized in that, In step (1), the mass ratio of the electroplating sludge water quenching residue to the nano SiO2 is 100:(1-3); The pressure of the airflow is 0.6-0.8 MPa; In step (1), the self-collision time between the nano SiO2 particle stream and the electroplating sludge water quenching slag is 10-15 min.

5. The method for preparing nanocomposite modified electroplating sludge powder as described in claim 1, characterized in that, In step (2), the temperature of the in-situ sol-gel coupling is 110-120℃ and the time is 15-30min.

6. A nanocomposite modified electroplating sludge powder, characterized in that, The nanocomposite modified electroplating sludge powder is prepared by the method described in any one of claims 1-5.

7. A cementitious material, characterized in that, The gelling material includes the nanocomposite modified electroplating sludge powder as described in claim 6.

8. A type of concrete, characterized in that, The concrete comprises cementitious materials, standard sand, aggregates, water-reducing agents, and water. The components of the gelling material include the nanocomposite modified electroplating sludge micro powder as described in claim 6.

9. The concrete as described in claim 8, characterized in that, The mass ratio of the cementitious material, standard sand, and aggregate is (400~500):(700~900):(1000~1200); By weight, the cementitious material comprises: 300-400 parts of ordinary silicate cement, 60-150 parts of nano-composite modified electroplating sludge powder, and 40-60 parts of fly ash. The mass ratio of the water-reducing agent to the ordinary silicate cement is (3-6):(300-400); The mass ratio of water to ordinary silicate cement is (160-200):(300-400).

10. A concrete component, characterized in that, The concrete component is prepared using the concrete as described in claim 8 or 9, comprising the following steps: S1. Dry-mix the gelling material evenly, add water and water-reducing agent, stir, and obtain a mixed slurry; S2. Add standard sand and aggregate to the mixed slurry, stir evenly, pour into a mold, vibrate, and cure to obtain the concrete component.

Images