阅读说明：本技术 绿色环保混凝土减水剂及其制备方法 (Green environment-friendly concrete water reducing agent and preparation method thereof ) 是由 孙超 孙红宾 张恒春 于 2021-10-09 设计创作，主要内容包括：本发明公开了一种绿色环保混凝土减水剂及其制备方法,通过回收利用造纸废液中的木质素磺酸盐并对其进行处理,得到了一种具有良好减水性能的绿色环保混凝土减水剂。本发明回收工业废水作为原料,利于环境保护,并且本发明能够延缓减水剂变质进程,提升使用寿命,拓展了木质素磺酸盐减水剂的应用范围。(The invention discloses a green environment-friendly concrete water reducing agent and a preparation method thereof. The method has the advantages that the industrial wastewater is recycled as the raw material, the environmental protection is facilitated, the deterioration process of the water reducing agent can be delayed, the service life is prolonged, and the application range of the lignosulfonate water reducing agent is expanded.)

1. The green environment-friendly concrete water reducing agent is characterized in that: the environment-friendly concrete water reducing agent is composed of one or two of porous lignosulfonate, dispersed lignosulfonate and hydrophilic lignosulfonate.

2. The green environment-friendly concrete water reducer according to claim 1, characterized in that: the green environment-friendly concrete water reducing agent is prepared from dispersed porous lignosulfonate and hydrophilic lignosulfonate in a mass ratio of (1.25-2): 1 of the mixture formed.

3. The green environment-friendly concrete water reducer according to claim 2, characterized in that: the environment-friendly concrete water reducing agent is prepared from dispersed porous lignosulfonate and hydrophilic lignosulfonate in a mass ratio of 1.75: 1 of the mixture formed.

4. The green environment-friendly concrete water reducer according to claim 1, characterized in that the preparation method of the porous lignosulfonate is as follows:

filtering X1 papermaking red liquor to remove solid insoluble substances, adding a sodium hydroxide aqueous solution with the concentration of 1-2 mol/L to adjust the pH value to 12-13, then adding calcium sulfate to enable the concentration of calcium sulfate in the papermaking red liquor to be 30-45 g/L, heating to 35-40 ℃, reacting at the stirring speed of 180-240 rpm for 1.5-3 h, filtering, drying, crushing and sieving with a sieve of 80-200 meshes to obtain waste water lignosulfonate for later use;

and X2, adding 10 parts by weight of the waste water lignosulfonate obtained in the step X1 into 400-500 parts by weight of water, mixing at a stirring speed of 240-360 rpm for 2-4 hours, adding 0.25-0.75 part by weight of nano ferroferric oxide particles, mixing at a stirring speed of 480-600 rpm for 4-6 hours, filtering, and mixing the filtered product with 20-30 wt% of dilute sulfuric acid in a ratio of 1: (27.5-35), heating to 80-95 ℃, mixing for 6-8 h at a stirring speed of 90-120 rpm, cooling to normal temperature, filtering, washing for 3-5 times, placing the product in a drying device, drying for 4-6 h at 80-100 ℃, crushing, and sieving with a sieve of 80-200 meshes to obtain the porous lignosulfonate.

5. The green environment-friendly concrete water reducer according to any one of claims 1 to 3, characterized in that the preparation method of the dispersed lignosulfonate is as follows:

filtering the Y1 papermaking red liquor to remove solid insoluble substances, adding a sodium hydroxide aqueous solution with the concentration of 1-2 mol/L to adjust the pH value to 12-13, then adding calcium sulfate to enable the concentration of calcium sulfate in the papermaking red liquor to be 30-45 g/L, heating to 35-40 ℃, reacting at the stirring speed of 180-240 rpm for 1.5-3 h, filtering, drying, crushing and sieving with a sieve of 80-200 meshes to obtain waste water lignosulfonate for later use;

y2, adding 10 parts by weight of the waste water lignosulfonate obtained in the step Y1 into 400-500 parts by weight of water, mixing for 2-4 hours at a stirring speed of 240-360 rpm, adding 0.25-0.75 part by weight of nano ferroferric oxide particles, mixing for 4-6 hours at a stirring speed of 480-600 rpm, filtering, mixing the filtered product with 20-30 wt% of dilute sulfuric acid in a ratio of 1: (27.5-35), heating to 80-95 ℃, mixing for 6-8 h at a stirring speed of 90-120 rpm, cooling to normal temperature, filtering, washing for 3-5 times, placing the product in a drying device, drying for 4-6 h at 80-100 ℃, crushing, and sieving with a sieve of 80-200 meshes to obtain the porous lignosulfonate for later use;

y3, dissolving 10-15 parts of alpha-methyl cinnamic acid and 12.5-25 parts of 1-hydroxybenzotriazole in 25-37.5 parts of dimethyl sulfoxide by weight, and mixing at a stirring speed of 120-180 rpm for 45-60 min under the protection of nitrogen to obtain a uniform mixture A for later use;

y4 is prepared by adding 0.5-1.25 parts by weight of formaldehyde and 10-15 parts by weight of porous lignosulfonate obtained in the step Y2 into the mixture A obtained in the step Y3, heating to 75-85 ℃, reacting for 3-4 hours at a stirring speed of 120-180 rpm under the protection of nitrogen, cooling to normal temperature to obtain a reaction mixture I, adding the reaction mixture I into 325-400 parts by weight of isopropanol, standing for 12-18 hours, centrifuging for 10-15 minutes at a speed of 8000-12000 rpm, filtering and separating precipitates, washing the separated precipitates with alcohol for 3-5 times, placing in a freeze-drying device, freeze-drying for 8-12 hours at-60-80 ℃, crushing and sieving with a sieve of 80-200 meshes to obtain the dispersed lignosulfonate.

6. The preparation method of the green environment-friendly concrete water reducer according to any one of claims 2 to 5, characterized by comprising the following steps: s1, taking porous lignosulfonate and dispersed lignosulfonate, wherein the mass ratio of the porous lignosulfonate to the dispersed lignosulfonate is (1.25-2): drying for 2-4 h at the temperature of 1, 40-60 ℃ for later use; s2, mixing the dried porous lignosulfonate and the dispersed lignosulfonate at a stirring speed of 120-240 rpm for 1-2 h to obtain the green environment-friendly concrete water reducer.

Technical Field

The invention relates to the technical field of concrete additives, in particular to a green environment-friendly concrete water reducing agent and a preparation method thereof.

Background

The vigorous development of the paper industry causes serious pollution and damage to the environment and the global ecosystem, the paper industry is an industry with high pollution to the environment, and the pollution is mainly caused by waste liquid generated by treating plant fiber raw materials with acid and alkali in the paper making process. The papermaking red liquor is a waste liquor produced by a sulfite pulping method, and is named because the waste liquor is reddish brown, and acid sulfite containing excessive sulfurous acid is used as a cooking liquor, and the cooking liquor is heated in a pressure cooker to dissolve and remove impurities such as lignin in plant components. Due to the characteristics of a sulfite pulping method, papermaking red liquor contains a large amount of lignosulfonate, and is directly discharged into river water to cause huge environmental pollution, the lignosulfonate has a recycling value, and the recycling of waste water lignosulfonate and the application of the lignosulfonate to other fields have great significance for green economy.

Patent CN201911331825.0 discloses an aliphatic water reducing agent prepared from lignosulfonate wastewater and a synthesis process thereof, wherein the aliphatic water reducing agent is prepared from the lignosulfonate wastewater so as to realize the resource reasonable utilization of the lignosulfonate wastewater, but the problem of excessive addition amount required in the process of the invention is solved. Patent 201710866089.3 provides a method for preparing an anionic and cationic compound lignosulfonate water reducing agent, which comprises introducing polyethylene glycol long hydrophilic chains into lignosulfonate molecules through a grafting reaction, and then preparing the anionic and cationic compound amphoteric water reducing agent through electrostatic self-assembly with a cationic surfactant, but the problem of water reducing efficiency reduction caused by water reducing agent agglomeration may occur in application.

Disclosure of Invention

In view of the above-mentioned defects of the prior art, the technical problems solved by the present invention are: (1) recovering and preparing the green environment-friendly concrete water reducing agent from the papermaking waste liquid; (2) the performance of the green environment-friendly concrete water reducing agent is improved according to the technical problems encountered in the actual production, the water reducing rate of the water reducing agent is improved, and the dispersibility of the concrete is improved.

A large amount of waste liquid is generated during the paper making process. The sulfite pulp waste water is also called paper making red liquor, and is waste liquor produced when the paper making industry uses acid pulping. Because the acid pulping uses the mixed liquor of sulfate and sulfite to produce paper pulp, the papermaking red liquor contains a large amount of lignosulfonate, has high organic matter content, is acidic, has pH of 1-4, and can be deposited at the bottom of riverbeds and lakes after being directly discharged into a natural water area, thereby harming aquatic organisms and polluting water bodies.

The inventor finds that a large amount of lignosulfonate can be recycled in the papermaking red liquor, sodium hydroxide and calcium sulfate are added into the simply treated papermaking red liquor, the chelating amount of chelating groups in waste liquor is saturated by calcium ions, and the lignosulfonate is obtained through precipitation and separation. The lignosulfonate powder extracted from the papermaking red liquor by the method also has certain defects, and because lignosulfonate is separated out due to the reduction of solubility to obtain a precipitate, the concentration of all parts of substances in the papermaking red liquor is not uniform and stable under an ideal condition, so that the lignosulfonate is aggregated to different degrees in the precipitation process. Because the agglomeration degrees are different, the obtained precipitate needs to be dried and then physically crushed into powder, but the physical crushing operation cannot improve the surface of the lignosulfonate and only can physically reduce the particle size of the lignosulfonate, when the obtained lignosulfonate is used as a water reducing agent, the combination with other components in concrete depends on the fineness degree of physical crushing, and the water reducing rate is only 8-10%. The inventor finds that nano ferroferric oxide particles are added into lignosulfonate mixture to serve as a template agent to be combined with lignosulfonate, then sulfuric acid treatment is carried out to remove ferroferric oxide through etching, a fine and porous structure can be formed on the surface of lignosulfonate, the surface area of lignosulfonate is increased from a molecular layer, and therefore the binding capacity with other components of concrete and water molecules is improved.

In order to achieve the purpose, the invention adopts the following technical scheme:

the environment-friendly concrete water reducing agent is composed of one or two of porous lignosulfonate, dispersive lignosulfonate and hydrophilic lignosulfonate.

Preferably, the green environment-friendly concrete water reducing agent is prepared from porous lignosulfonate and dispersed lignosulfonate in a mass ratio of (1.25-2): 1 of the mixture formed.

Preferably, the preparation method of the porous lignosulfonate is as follows:

filtering X1 papermaking red liquor to remove solid insoluble substances, adding a sodium hydroxide aqueous solution with the concentration of 1-2 mol/L to adjust the pH value to 12-13, then adding calcium sulfate, wherein the concentration of calcium sulfate in the papermaking red liquor is 30-45 g/L, heating to 35-40 ℃, reacting at the stirring speed of 180-240 rpm for 1.5-3 h, filtering, drying, crushing, and sieving with a sieve of 80-200 meshes to obtain waste water lignosulfonate for later use;

and X2, adding 10 parts by weight of the waste water lignosulfonate obtained in the step X1 into 400-500 parts by weight of water, mixing at a stirring speed of 240-360 rpm for 2-4 hours, adding 0.25-0.75 part by weight of nano ferroferric oxide particles, mixing at a stirring speed of 480-600 rpm for 4-6 hours, filtering, and mixing the filtered product with 20-30 wt% of dilute sulfuric acid in a ratio of 1: (27.5-35), heating to 80-95 ℃, mixing for 6-8 h at a stirring speed of 90-120 rpm, cooling to normal temperature, filtering, washing for 3-5 times, placing the product in a drying device, drying for 4-6 h at 80-100 ℃, crushing, and sieving with a sieve of 80-200 meshes to obtain the porous lignosulfonate.

Although the porous lignosulfonate has a better combination effect, the surface group components of the lignosulfonate are not changed, and in practical application, the lignosulfonate has a certain agglomeration phenomenon, so that the use efficiency is reduced. Through a large amount of production practices and improvements, the inventor finds that the porous lignosulfonate can bring sulfo groups during sulfuric acid etching, the sulfo groups can serve as leaving groups to provide reaction sites on the surface of the porous lignosulfonate, and on the other hand, the benzene ring structure is introduced into the porous lignosulfonate through alpha-methyl cinnamic acid and formaldehyde, so that the steric hindrance of porous lignosulfonate molecules can be improved, and the dispersibility of the wrapped concrete can be improved while the agglomeration of the porous lignosulfonate molecules is avoided.

Preferably, the preparation method of the dispersion type lignosulfonate is as follows:

filtering the Y1 papermaking red liquid to remove solid insoluble substances, adding a sodium hydroxide aqueous solution with the concentration of 1-2 mol/L to adjust the pH value to 12-13, then adding calcium sulfate, wherein the concentration of calcium sulfate in the papermaking red liquid is 30-45 g/L, heating to 35-40 ℃, reacting at the stirring speed of 180-240 rpm for 1.5-3 h, filtering, drying, crushing, and sieving with a sieve of 80-200 meshes to obtain waste water lignosulfonate for later use;

y2, adding 10 parts by weight of the waste water lignosulfonate obtained in the step Y1 into 400-500 parts by weight of water, mixing for 2-4 hours at a stirring speed of 240-360 rpm, adding 0.25-0.75 part by weight of nano ferroferric oxide particles, mixing for 4-6 hours at a stirring speed of 480-600 rpm, filtering, mixing the filtered product with 20-30 wt% of dilute sulfuric acid in a ratio of 1: (27.5-35), heating to 80-95 ℃, mixing for 6-8 h at a stirring speed of 90-120 rpm, cooling to normal temperature, filtering, washing for 3-5 times, placing the product in a drying device, drying for 4-6 h at 80-100 ℃, crushing, and sieving with a sieve of 80-200 meshes to obtain the porous lignosulfonate for later use;

y3, dissolving 10-15 parts of alpha-methyl cinnamic acid and 12.5-25 parts of 1-hydroxybenzotriazole in 25-37.5 parts of dimethyl sulfoxide by weight, and mixing at a stirring speed of 120-180 rpm for 45-60 min under the protection of nitrogen to obtain a uniform mixture A for later use;

y4 is prepared by adding 0.5-1.25 parts by weight of formaldehyde and 10-15 parts by weight of porous lignosulfonate obtained in the step Y2 into the mixture A obtained in the step Y3, heating to 75-85 ℃, reacting for 3-4 hours at a stirring speed of 120-180 rpm under the protection of nitrogen, cooling to normal temperature to obtain a reaction mixture I, adding the reaction mixture I into 325-400 parts by weight of isopropanol, standing for 12-18 hours, centrifuging for 10-15 minutes at a speed of 8000-12000 rpm, filtering and separating precipitates, washing the separated precipitates with alcohol for 3-5 times, placing in a freeze-drying device, freeze-drying for 8-12 hours at-60-80 ℃, crushing and sieving with a sieve of 80-200 meshes to obtain the dispersed lignosulfonate.

The inventor further improves the method, diethylenetriamine molecules are introduced into the dispersed lignosulfonate through aminomethylation to increase the hydrophilicity, the binding capacity of the dispersed lignosulfonate and water molecules is further increased from the molecular layer, the dispersed lignosulfonate can be quickly bound with the water molecules in concrete and can form a film on the surface of concrete particles, and the dispersibility of the concrete is increased. In addition, the inventor also finds that groups such as quaternary ammonium salt groups formed after diethylenetriamine is introduced into the molecular chain of the dispersed lignosulfonate have an inhibiting effect on microorganisms, and can inhibit the decomposition of common white rot fungi on lignin so as to avoid the deterioration of the lignosulfonate water reducing agent.

Preferably, the preparation method of the hydrophilic lignosulfonate is as follows:

filtering the Z1 papermaking red liquor to remove solid insoluble substances, adding a sodium hydroxide aqueous solution with the concentration of 1-2 mol/L to adjust the pH value to 12-13, then adding calcium sulfate to enable the concentration of calcium sulfate in the papermaking red liquor to be 30-45 g/L, heating to 35-40 ℃, reacting at the stirring speed of 180-240 rpm for 1.5-3 h, filtering, drying, crushing and sieving with a sieve of 80-200 meshes to obtain waste water lignosulfonate for later use;

and Z2, adding 10 parts by weight of the waste water lignosulfonate obtained in the step Z1 into 400-500 parts by weight of water, mixing at a stirring speed of 240-360 rpm for 2-4 hours, adding 0.25-0.75 part by weight of nano ferroferric oxide particles, mixing at a stirring speed of 480-600 rpm for 4-6 hours, filtering, mixing the filtered product with 20-30 wt% of dilute sulfuric acid at a ratio of 1: (27.5-35), heating to 80-95 ℃, mixing for 6-8 h at a stirring speed of 90-120 rpm, cooling to normal temperature, filtering, washing for 3-5 times, placing the product in a drying device, drying for 4-6 h at 80-100 ℃, crushing, and sieving with a sieve of 80-200 meshes to obtain the porous lignosulfonate for later use;

z3, taking 10-15 parts of alpha-methyl cinnamic acid and 12.5-25 parts of 1-hydroxybenzotriazole by weight, dissolving in 25-37.5 parts of dimethyl sulfoxide, and mixing at a stirring speed of 120-180 rpm for 45-60 min under the protection of nitrogen to obtain a uniform mixture A for later use;

z4, adding 0.5-1.25 parts by weight of formaldehyde and 10-15 parts by weight of porous lignosulfonate obtained in the step Z2 into the mixture A obtained in the step Z3, heating to 75-85 ℃, reacting for 3-4 hours at a stirring speed of 120-180 rpm under the protection of nitrogen, cooling to normal temperature to obtain a reaction mixture I, adding the reaction mixture I into 325-400 parts by weight of isopropanol, standing for 12-18 hours, centrifuging for 10-15 minutes at a speed of 8000-12000 rpm, filtering and separating precipitates, washing the separated precipitates for 3-5 times with alcohol, placing the precipitates in a freeze-drying device, freeze-drying for 8-12 hours at-60-80 ℃, crushing and sieving with a sieve of 80-200 meshes to obtain dispersed lignosulfonate for later use;

z5 is prepared by adding 10-15 parts by weight of the dispersed lignosulfonate obtained in the step Z4 into dimethyl sulfoxide, ultrasonically dispersing for 30-45 min at 550-700W to obtain a mixture B with the mass fraction of 7.5-10 wt% of the dispersed lignosulfonate, adding 1-2 mol/L hydrochloric acid aqueous solution and 1-2 mol/L sodium hydroxide aqueous solution to control the pH of the mixture B to be 10-11, adding 17.5-25 parts of diethylenetriamine and 10-15 parts of 35-40 wt% formaldehyde aqueous solution into the mixture B, heating to 75-85 ℃, mixing for 3-4 h at a stirring speed of 180-240 rpm, cooling to normal temperature to obtain a reaction mixture II, adding 325-400 parts of isopropanol into the reaction mixture II, standing for 12-18 h, centrifuging for 10-15 min at a speed of 8000-12000 rpm, filtering and separating precipitates, washing the separated precipitate with alcohol for 3-5 times, placing the precipitate in a drying device, drying the precipitate for 8-12 hours at the temperature of 40-50 ℃, and crushing the precipitate and sieving the precipitate with a sieve of 80-200 meshes to obtain the hydrophilic lignosulfonate.

The preparation method of the green environment-friendly concrete water reducer comprises the following steps:

s1, taking porous lignosulfonate and dispersed lignosulfonate, wherein the mass ratio of the porous lignosulfonate to the dispersed lignosulfonate is (1.25-2): drying for 2-4 h at the temperature of 1, 40-60 ℃ for later use;

s2, mixing the dried porous lignosulfonate and the dispersed lignosulfonate at a stirring speed of 120-240 rpm for 1-2 h to obtain the green environment-friendly concrete water reducer.

The introduction and the function of each raw material in the formula of the invention are as follows:

papermaking red liquor: compared with the waste liquid obtained by alkaline pulping in the paper industry, the waste liquid generated in the acid pulping is red, and the red liquid contains a large amount of lignosulfonate and can be recycled.

According to the nano ferroferric oxide, nano ferroferric oxide particles are added into lignosulfonate mixture to serve as a template agent to be combined with lignosulfonate, then sulfuric acid is used for processing and etching to remove the ferroferric oxide, a fine and porous structure can be formed on the surface of the lignosulfonate, the surface area of the lignosulfonate is increased from a molecular level, and therefore the binding capacity with other components of concrete and water molecules is improved. The particle size of the nano ferroferric oxide particles is 20-50 nm.

Calcium sulfate: inorganic substances, white monoclinic crystals or crystalline powders, are used as the raw material for providing a source of calcium ions in the present invention.

α -methyl cinnamic acid: organic matter, white crystalline powder, is introduced into lignosulfonate molecules to provide a benzene ring structure.

Diethylenetriamine: the organic material is a yellow, hygroscopic, transparent viscous liquid, and is used as a raw material for introducing a hydrophilic group into a lignosulfonate molecule in the present invention.

On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.

The invention has the beneficial effects that:

compared with the prior art, the green environment-friendly concrete water reducing agent is extracted and prepared from the papermaking waste liquid, reduces the pollution of the papermaking waste liquid, and is beneficial to environmental protection.

Compared with the prior art, the method improves the lignosulfonate by physical and chemical methods, improves the water reducing rate of the water reducing agent and increases the dispersibility of the concrete.

Compared with the prior art, the invention has a certain inhibiting effect on common lignin decomposition microorganisms, can slow down the deterioration of the water reducing agent and prolong the service life of the water reducing agent.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.

Some raw material parameters in the comparative examples and examples of the invention are as follows:

the papermaking red liquor, the lignosulfonate content is 27%, and the Xinxiang city is a new paper making factory;

nano ferroferric oxide particles with the average particle size of 40nm, Hangzhou Wanjing new materials Co., Ltd;

alpha-methyl cinnamic acid, shanghai kaiser chemical ltd, CAS No.: 1199-77-5 Diethylenetriamine, Kagawa Kogyo Co., Ltd., CAS No.: 111-40-0.

Example 1

The green environment-friendly concrete water reducing agent comprises porous lignosulfonate as a component.

The preparation method of the porous lignosulfonate comprises the following steps:

filtering X1 papermaking red liquor to remove solid insoluble substances, adding a sodium hydroxide aqueous solution with the concentration of 1mol/L to adjust the pH value to 13, then adding calcium sulfate to ensure that the concentration of calcium sulfate in the papermaking red liquor is 35g/L, heating to 40 ℃, reacting at the stirring speed of 180rpm for 3 hours, filtering, drying, crushing and sieving with a 120-mesh sieve to obtain waste water lignosulfonate for later use;

x2 adding 10kg of waste water lignosulfonate obtained in the step X1 into 500kg of water, mixing for 3h at a stirring speed of 240rpm, adding 0.25kg of nano ferroferric oxide particles, mixing for 4h at a stirring speed of 600rpm, filtering, mixing the filtered product with 30 wt% of dilute sulfuric acid in a mixing ratio of 1: 27.5, heating to 95 ℃, mixing for 6h at the stirring speed of 120rpm, cooling to normal temperature, filtering, washing for 3 times, placing the product in a drying device, drying for 6h at 80 ℃, crushing and sieving with a 120-mesh sieve to obtain the porous lignosulfonate.

Example 2

The green environment-friendly concrete water reducing agent comprises the components of dispersed lignosulfonate.

The preparation method of the dispersed lignosulfonate comprises the following steps:

filtering the Y1 papermaking red liquid to remove solid insoluble substances, adding a sodium hydroxide aqueous solution with the concentration of 1mol/L to adjust the pH value to 13, then adding calcium sulfate to ensure that the concentration of calcium sulfate in the papermaking red liquid is 35g/L, heating to 40 ℃, reacting at the stirring speed of 180rpm for 3 hours, filtering, drying, crushing and sieving with a 120-mesh sieve to obtain waste water lignosulfonate for later use;

y2 adding 10kg of waste water lignosulfonate obtained in the step Y1 into 500kg of water, mixing for 3h at a stirring speed of 240rpm, adding 0.25kg of nano ferroferric oxide particles, mixing for 4h at a stirring speed of 600rpm, filtering, mixing the filtered product with 30 wt% of dilute sulfuric acid in a mixing ratio of 1: 27.5, heating to 95 ℃, mixing for 6 hours at a stirring speed of 120rpm, cooling to normal temperature, filtering, washing for 3 times, placing the product in a drying device, drying for 6 hours at 80 ℃, crushing, and sieving with a 120-mesh sieve to obtain porous lignosulfonate for later use;

y3 dissolving 10kg of alpha-methyl cinnamic acid and 12.5kg of 1-hydroxybenzotriazole in 30kg of dimethyl sulfoxide, and mixing at a stirring speed of 180rpm for 45min under the protection of nitrogen to obtain a uniform mixture A for later use;

y4 adding 0.75kg of formaldehyde and 10kg of the porous lignosulfonate obtained in the step Y2 into the mixture A obtained in the step Y3, heating to 85 ℃, reacting for 3 hours at a stirring speed of 180rpm under the protection of nitrogen, cooling to normal temperature to obtain a reaction mixture I, adding the reaction mixture I into 325kg of isopropanol, standing for 12 hours, centrifuging for 10 minutes at a speed of 12000rpm, filtering and separating precipitates, washing the separated precipitates with alcohol for 3 times, placing in a freeze-drying device, freeze-drying for 8 hours at-60 ℃, crushing and sieving with a 120-mesh sieve to obtain the dispersed lignosulfonate.

Example 3

The green environment-friendly concrete water reducing agent comprises hydrophilic lignosulfonate.

The preparation method of the hydrophilic lignosulfonate comprises the following steps:

filtering the Z1 papermaking red liquid to remove solid insoluble substances, adding a sodium hydroxide aqueous solution with the concentration of 1mol/L to adjust the pH value to 13, then adding calcium sulfate to ensure that the concentration of calcium sulfate in the papermaking red liquid is 35g/L, heating to 40 ℃, reacting at the stirring speed of 180rpm for 3 hours, filtering, drying, crushing and sieving with a 120-mesh sieve to obtain waste water lignosulfonate for later use;

z2 10kg of the waste water lignosulfonate obtained in the step Z1 was added to 500kg of water, mixed for 3 hours at a stirring speed of 240rpm, added with 0.25kg of nano ferroferric oxide particles, mixed for 4 hours at a stirring speed of 600rpm, filtered, and the filtered product was mixed with 30 wt% of dilute sulfuric acid in a mixing ratio of 1: 27.5, heating to 95 ℃, mixing for 6 hours at a stirring speed of 120rpm, cooling to normal temperature, filtering, washing for 3 times, placing the product in a drying device, drying for 6 hours at 80 ℃, crushing, and sieving with a 120-mesh sieve to obtain porous lignosulfonate for later use;

z3 dissolving 10kg of alpha-methyl cinnamic acid and 12.5kg of 1-hydroxybenzotriazole in 30kg of dimethyl sulfoxide, and mixing at a stirring speed of 180rpm for 45min under the protection of nitrogen to obtain a uniform mixture A for later use;

z4, adding 0.75kg of formaldehyde and 10kg of porous lignosulfonate obtained in the step Z2 into the mixture A obtained in the step Z3, heating to 85 ℃, reacting for 3 hours at a stirring speed of 180rpm under the protection of nitrogen, cooling to normal temperature to obtain a reaction mixture I, adding the reaction mixture I into 325kg of isopropanol, standing for 12 hours, centrifuging for 10 minutes at a speed of 12000rpm, filtering and separating precipitates, washing the separated precipitates with alcohol for 3 times, placing in a freeze-drying device, freeze-drying for 8 hours at-60 ℃, crushing and sieving with a 120-mesh sieve to obtain dispersed lignosulfonate for later use;

z5 adding 10kg of the dispersed lignosulfonate obtained in the step Z4 into dimethyl sulfoxide, ultrasonically dispersing for 45min at 550W to obtain a mixture B with the mass fraction of the dispersed lignosulfonate being 7.5 wt%, adding 1mol/L hydrochloric acid aqueous solution and 1mol/L sodium hydroxide aqueous solution to control the pH of the mixture B to be 11, adding 17.5kg of diethylenetriamine and 12.5kg of 35 wt% formaldehyde aqueous solution into the mixture B, heating to 75 ℃, mixing for 3h at the stirring speed of 240rpm, cooling to normal temperature to obtain a reaction mixture II, adding the reaction mixture II into 325kg of isopropanol, standing for 12h, centrifuging for 10min at 12000rpm, filtering and separating precipitates, washing the separated precipitates with alcohol for 3 times, placing in a drying device, drying for 12h at 40 ℃, crushing and sieving with a 120-mesh sieve, obtaining the hydrophilic lignosulfonate.

Example 4

The green environment-friendly concrete water reducing agent is prepared by adopting the following method:

s1, taking porous lignosulfonate and dispersed lignosulfonate, wherein the mass ratio of the porous lignosulfonate to the dispersed lignosulfonate is 1.75: drying at 1, 60 deg.C for 2 h;

s2, mixing the dried porous lignosulfonate and the dispersed lignosulfonate at a stirring speed of 120rpm for 2 hours to obtain the green environment-friendly concrete water reducer.

The preparation method of the porous lignosulfonate was consistent with that of example 1, and the preparation method of the dispersed lignosulfonate was consistent with that of example 2.

Example 5

The green environment-friendly concrete water reducing agent is prepared by adopting the following method:

s1, taking porous lignosulfonate and hydrophilic lignosulfonate, wherein the mass ratio of the porous lignosulfonate to the hydrophilic lignosulfonate is 1.75: drying at 1, 60 deg.C for 2 h;

s2, mixing the dried porous lignosulfonate and the hydrophilic lignosulfonate at a stirring speed of 120rpm for 2 hours to obtain the green environment-friendly concrete water reducer.

The preparation method of the porous lignosulfonate is consistent with that of example 1, and the preparation method of the hydrophilic lignosulfonate is consistent with that of example 3.

Example 6

The green environment-friendly concrete water reducing agent is prepared by adopting the following method:

s1, taking dispersed lignosulfonate and hydrophilic lignosulfonate, wherein the mass ratio of the dispersed lignosulfonate to the hydrophilic lignosulfonate is 1.75: drying at 1, 60 deg.C for 2 h;

s2, mixing the dried dispersed lignosulfonate and the hydrophilic lignosulfonate at a stirring speed of 120rpm for 2 hours to obtain the green environment-friendly concrete water reducer.

The preparation method of the dispersion type lignosulfonate is consistent with that of example 2, and the preparation method of the hydrophilic type lignosulfonate is consistent with that of example 3.

Comparative example 1

The green environment-friendly concrete water reducing agent comprises the components of waste water lignosulfonate.

The preparation method of the waste water lignosulfonate comprises the following steps:

filtering the papermaking red liquid to remove solid insoluble substances, adding a sodium hydroxide aqueous solution with the concentration of 1mol/L to adjust the pH value to 13, then adding calcium sulfate, wherein the concentration of the calcium sulfate in the papermaking red liquid is 35g/L, heating to 40 ℃, reacting at the stirring speed of 180rpm for 3 hours, filtering, drying, crushing and sieving with a 120-mesh sieve to obtain the waste water lignosulfonate.

Test example 1

The water reducing rate test of the green environment-friendly concrete water reducing agent is carried out according to the specific requirements of JGJ 56-1984 concrete water reducing agent quality standard and test method concrete water reducing agent experimental method. Test for C in concrete Cement Clinker₃The content of A is 6%, using No. 425 ordinary portland cement using dihydrate gypsum as the set adjusting agent, the sand uses the sand in the second zone, the stone is gravel with the particle size of 8mm, and the cement consumption is 305kg/m³. The addition amount of the green environment-friendly concrete water reducing agent in the concrete is 0.2 wt%. Each set tested 5 samples and the results averaged. The water reducing rate test results of the green environment-friendly concrete water reducing agent are shown in table 1.

Table 1: water reducing rate test result table of green environment-friendly concrete water reducing agent

Test set	Water loss (%)
		Example 1	10.6
Example 2	12.2
		Example 3	13.7
Example 4	14.4
		Example 5	15.7
Example 6	17.6
		Comparative example 1	8.1

The comprehensive effects of the absorption and dispersion effect, the wetting effect and the lubricating effect of the water reducing agent enable the commercial concrete to be uniformly mixed by using a small amount of water, and the workability of the freshly mixed commercial concrete is improved. Generally, the higher the water reducing ratio of the water reducing agent, the better the performance thereof in exerting the water reducing effect. It can be seen from the comparison between the examples and the comparative examples that the example 6 has a good water reducing effect, which is higher than the water reducing rate of 8-10% of the common lignosulfonate, and the reason for this is probably that the lignosulfonate surface forms a fine porous structure, the surface area of the lignosulfonate is increased from the molecular layer, and the diethylenetriamine molecules are introduced through aminomethylation to increase the hydrophilicity, so that the binding capacity with water molecules is improved.

Test example 2

The slump test of the green environment-friendly concrete water reducer is carried out according to the specific requirements of JGJ 56-1984 concrete water reducer quality standard and test method appendix C concrete test method C1 slump and slump loss of the water reducer. Test for C in concrete Cement Clinker₃The content of A is 6%, using No. 425 ordinary portland cement using dihydrate gypsum as the set adjusting agent, the sand uses the sand in the second zone, the stone is gravel with the particle size of 8mm, and the cement consumption is 305kg/m³. The addition amount of the green environment-friendly concrete water reducing agent in the concrete is 0.2 wt%. The diameter of the bottom of the collapse barrel is 200mm, the diameter of the top of the collapse barrel is 100mm, the height of the collapse barrel is 300mm, and the wall thickness of the collapse barrel is 2 mm; the diameter of the tamper is 16mm, the length of the tamper is 600mm, and the end part of the tamper is ground to be round. 5 samples were tested per group and concrete mix slump was expressed in cm, the results averaged to 0.5 cm. The slump test results of the green environment-friendly concrete water reducer are shown in Table 2.

Table 2: slump test result table of green environment-friendly concrete water reducer

The water reducing agent is a dispersant in a broad sense, the dispersibility of concrete particles is improved by adding the water reducing agent, the fluidity of the concrete is enhanced after the water reducing agent is added, and the slump is correspondingly improved. As can be seen by comparing the examples and the comparative examples, the lignosulfonate modified in multiple steps can improve the dispersibility of concrete. The reason for this may be that alpha-methyl cinnamic acid and formaldehyde introduce a benzene ring structure into the porous lignosulfonate, which can improve the steric hindrance of the porous lignosulfonate molecules, and can increase the dispersibility of the coated concrete while avoiding agglomeration thereof, and the introduction of hydrophilic groups can enable the water reducing agent to be rapidly combined with water molecules in the concrete and to form a film on the surface of concrete particles, thereby further increasing the dispersibility of the concrete.

Test example 3

The bacteriostasis test of the green environment-friendly concrete water reducer is carried out according to the specific requirements of WS/T650-plus 2019 'evaluation method for antibacterial and bacteriostatic effects'. According to the field of use of the lignosulfonate water reducing agent, Phanerochaete chrysosporium (ATCC 24725) was selected as an experimental strain for the test, and the strain was provided by Richu Biotech, Inc., Jiangsu. The diluent adopts 0.03mol/L phosphate buffer solution with the pH value of 7.2; the Phanerochaete chrysosporium is cultured in a Sabouraud agar medium. The phanerochaete chrysosporium is cultured for 72h, the final result is observed, the test is repeated for 3 times, and the result is averaged.

Test set	Bacteriostatic ratio (%)
		Example 1	29
Example 2	36
		Example 3	67
Comparative example 1	23

The higher the bacteriostasis rate is, the better the bacteriostasis effect is, according to the definition in the WS/T650 plus 2019 'evaluation method of antibacterial and bacteriostasis effect' result judgment, the bacteriostasis rate is more than or equal to 50-90 percent, and the judgment has the bacteriostasis effect; the bacteriostasis rate is more than or equal to 90 percent, and the antibacterial effect is stronger. As shown by comparing the examples and the comparative examples, the hydrophilic lignosulfonate has a bacteriostatic effect on Phanerochaete chrysosporium, and the other examples have no bacteriostatic effect. The reason may be that groups such as quaternary ammonium salt groups formed after the diethylenetriamine is introduced into the molecular chain of the lignosulfonate have an inhibiting effect on phanerochaete chrysosporium, and can inhibit the phanerochaete chrysosporium from decomposing lignin, so that the deterioration of the lignosulfonate water reducing agent is avoided.

The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.