Environment-friendly brick carving blank material and preparation process thereof

Abstract

The invention relates to the technical field of building materials, in particular to an environment-friendly brick carving blank and a preparation process thereof. The environment-friendly brick carving blank material comprises the following components in parts by weight: 40-50 parts of waste concrete, 30-40 parts of steel slag powder, 10-20 parts of fly ash, 5-15 parts of modified charcoal, 3-8 parts of cement, 30-40 parts of modified clay, 30-50 parts of water and 0.2-0.5 part of a water reducing agent. The environment-friendly brick carving blank material is prepared from the waste concrete, the steel slag powder, the fly ash, the modified charcoal and the clay, acidic groups on the modified charcoal act on the surface of the modified clay, the interaction force between the materials is increased, the strength of the brick carving blank material is improved, and the service life of the brick carving blank material is prolonged. The water permeability and the adsorption capacity of the brick carving blank are enhanced, and meanwhile the problems of land resource waste and environmental pollution caused by solid waste accumulation are solved.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to an environmentally friendly brick carving blank and its preparation process. Background Technology

[0002] With increasing environmental awareness and the urgent need for resource recycling, traditional brick carving material production methods face numerous challenges. Traditional brick carving materials rely on natural resources such as clay, whose extraction damages land resources. As clay resources gradually deplete, raw material supply faces shortages. Furthermore, the firing process generates large amounts of pollutants such as carbon dioxide and sulfur dioxide, causing serious environmental pollution. At the same time, traditional processes are energy-intensive and inefficient, making it difficult to meet market demands for environmentally friendly, efficient, and high-quality brick carving products.

[0003] Therefore, we propose an environmentally friendly brick carving blank and its preparation process. Summary of the Invention

[0004] The purpose of this invention is to provide an environmentally friendly brick carving blank and its preparation process to solve the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A process for preparing an environmentally friendly brick carving blank includes the following steps: Step 1: Mix waste concrete, steel slag powder, fly ash, modified biochar, and modified clay evenly to obtain a mixed solid. Step 2: Pour water into the mixed solids and stir evenly, then add cement and water-reducing agent and stir evenly to obtain a mixed slurry; press the mixed slurry into shape, demold it, and obtain the environmentally friendly brick carving blank.

[0006] In a more optimized manner, the environmentally friendly brick carving blank material comprises the following weight components: 40-50 parts waste concrete, 30-40 parts steel slag powder, 10-20 parts fly ash, 5-15 parts modified biochar, 3-8 parts cement, 30-40 parts modified clay, 30-50 parts water, and 0.2-0.5 parts water-reducing agent.

[0007] The modified biochar is prepared in a more optimized manner as follows: Step 1: Dissolve ZnCl2 in deionized water, add sludge biochar, purge with nitrogen to remove oxygen for 30-40 min, add sodium borohydride aqueous solution dropwise under stirring at room temperature, complete the addition in 1-2 h, react for 22-24 h, centrifuge, wash with water, wash with anhydrous ethanol, dry to obtain the matrix; Step 2: Mix polyvinyl alcohol and boric acid aqueous solution evenly, add matrix and mercapto chitosan, stir evenly, then add calcium chloride aqueous solution, stir for 2-3 hours, let stand for 12-24 hours, wash with water and anhydrous ethanol, and dry to obtain aminated matrix; Step 3: Mix NaOH aqueous solution and carbon disulfide evenly, add aminated matrix, react at 20-30℃ for 20-40 min, then transfer to a water bath at 40-50℃ to continue the reaction for 4-8 h, cool to room temperature, filter, wash and dry to obtain modified biochar.

[0008] In a more optimized manner, in step 1, the mass ratio of ZnCl2, deionized water, sludge biochar, and sodium borohydride aqueous solution is 1:(30-40):(0.5-0.8):(30-40), and the concentration of sodium borohydride aqueous solution is 0.3-0.4 mol / L.

[0009] The optimized method for preparing the sludge biochar is as follows: After dewatering, drying, crushing, and passing through a 100-mesh sieve, the sludge is heated to 600-700℃ at a rate of 3-5℃ / min under a nitrogen atmosphere and held for 2-3 hours. It is then naturally cooled to room temperature and washed with water and anhydrous ethanol to obtain sludge biochar.

[0010] In a more optimized manner, in step 2, the mass ratio of polyvinyl alcohol, boric acid aqueous solution, matrix and thiol chitosan is 1:(40-50):(1-2):(0.5-1.0), and the concentration of boric acid aqueous solution is 1-3wt%.

[0011] A more optimized method for preparing the thiolated chitosan is as follows: Chitosan was dispersed in deionized water, and hydrochloric acid was added to adjust the pH to 6-7. Then, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide and L-cysteine ​​were added and mixed evenly. The mixture was reacted in the dark for 22-24 hours. After dialysis and drying, thiolated chitosan was obtained.

[0012] In a more optimized manner, the mass ratio of chitosan, deionized water, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide and L-cysteine ​​is 1:100:(7-8):(4.0-4.5):(2-4), and the concentration of hydrochloric acid is 1 mol / L.

[0013] Ideally, the concentration of the calcium chloride aqueous solution is 2-4 wt%, and its amount is 50-100 times the mass of polyvinyl alcohol.

[0014] Ideally, the mass ratio of the aminated matrix, NaOH aqueous solution, and carbon disulfide is 1:(10-15):(1-2), and the concentration of the NaOH aqueous solution is 40-50 wt%.

[0015] A more optimized method for preparing the modified clay is as follows: Clay was dispersed in a mixed solution of anhydrous ethanol and deionized water, and 3-aminopropyltriethoxysilane was added and mixed evenly. The pH of the system was adjusted to 4-5 using glacial acetic acid, and the reaction was carried out at 60-70℃ for 2-4 hours. After filtration, centrifugation and drying, modified clay was obtained.

[0016] More optimally, the mass ratio of the clay to anhydrous ethanol, deionized water, and 3-aminopropyltriethoxysilane is 1:(10-12):(2-4):(0.3-0.5).

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses sludge as raw material to prepare biochar, realizing the high-value utilization of solid waste and solving the problem of sludge disposal. The entire preparation process is mild and conforms to the principles of green chemistry. This invention uses biochar prepared from sludge as a framework, and loads it with nano-zero-valent zinc (nZVZ) to obtain a matrix, which effectively increases the specific surface area of ​​the biochar and enhances the contact area with pollutants, thereby improving the adsorption capacity. Next, the matrix is ​​compounded with polyvinyl alcohol (PVA) and thiolated chitosan, and calcium ions are used as a crosslinking agent to prepare an aminated matrix. This matrix not only retains high porosity to ensure rapid water penetration, but also utilizes the crosslinking effect of polymer chains to endow the material with excellent mechanical strength and durability, overcoming the shortcomings of poor strength in traditional porous materials. The thiolated chitosan is prepared through a condensation reaction between the amino groups of chitosan and the carboxyl groups of L-cysteine. Containing amino groups, the introduced thiols have a strong chelating ability for heavy metal ions such as lead (Pb²⁺), cadmium (Cd²⁺), and copper (Cu²⁺), enabling them to be firmly fixed and transformed, achieving efficient and stable heavy metal removal. Finally, the amino groups of the aminated matrix react with NaOH and carbon disulfide (CS2), and the grafted sulfur-containing dithiocarboxyl groups (-C(=S)-S-) further enhance the selective chelation with highly toxic heavy metal ions, significantly improving the selective adsorption of highly toxic heavy metals. The modified biochar prepared in this invention has a porous structure, which increases the porosity of the material, promotes water permeability, and enhances the water permeability of the brick carving material. At the same time, it has negatively charged functional groups such as carboxyl and hydroxyl groups, which are beneficial to the adsorption of positively charged metals in pollutants, achieving the effect of adsorbing and blocking pollutants.

[0018] 2. This invention uses waste concrete, steel slag powder, fly ash, modified biochar, and clay as raw materials to produce environmentally friendly brick carving blanks. The acidic groups on the modified biochar interact with the surface of the modified clay, increasing the interaction forces between the materials and improving the strength of the brick carving blanks. Applying solid waste to the preparation of sintered bricks not only improves the various properties of the brick carving blanks but also greatly alleviates the enormous pressure of resource shortages in my country, making it a green and environmentally friendly process. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Unless otherwise specified, all quantities below are by weight. It should be noted that there are no special restrictions on the suppliers of any of the raw materials involved in this invention. Exemplary examples include (in this embodiment): waste concrete: purchased from Wuhan Shengjingyang Environmental Protection Materials Co., Ltd.; steel slag powder: 40-70 mesh particle size, purchased from Shijiazhuang Zhengyu New Materials Technology Co., Ltd.; fly ash: Grade I fly ash, 200-300 mesh particle size, purchased from Jining Hengzhi New Building Materials Co., Ltd.; sludge: urban sludge, taken from a sewage treatment plant; clay: red clay, 200-300 mesh particle size, purchased from Qingdao Wanhong Mining Co., Ltd.; cement: silicate cement, P·O 42.5 grade, purchased from Hunan Xindingli New Materials Technology Co., Ltd.; water-reducing agent: polycarboxylate water-reducing agent, model PC-1030.

[0021] Example 1: A preparation process for an environmentally friendly brick carving blank, comprising the following steps: Step 1: Mix 40 parts waste concrete, 30 parts steel slag powder, 10 parts fly ash, 5 parts modified biochar, and 30 parts modified clay evenly to obtain a mixed solid. Step 2: Pour 30 parts water into the mixed solids and stir well. Then add 3 parts cement and 0.2 parts water-reducing agent and stir well to obtain a mixed slurry. After pressing the mixed slurry into shape, demold it to obtain an environmentally friendly brick carving blank. The preparation method of modified biochar is as follows: Step 1: After dewatering, drying, crushing and passing through a 100-mesh sieve, 5 portions of sludge were heated to 600℃ at 3℃ / min under a nitrogen atmosphere and held for 2 hours. After naturally cooling to room temperature, the sludge was washed with water and anhydrous ethanol to obtain sludge biochar. Dissolve 10 parts ZnCl2 in 300 parts deionized water, add 5 parts sludge biochar, purge with nitrogen to remove oxygen for 30 min, add 300 parts 0.3 mol / L sodium borohydride aqueous solution dropwise under stirring at room temperature, and add the solution dropwise over 1 h. After reacting for 22 h, centrifuge, wash with water, wash with anhydrous ethanol, and dry to obtain the matrix. Step 2: Disperse 2.5 parts of chitosan in 250 parts of deionized water, add 1 mol / L hydrochloric acid to adjust the pH to 6, then add 17.5 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 10 parts of N-hydroxysuccinimide and 5 parts of L-cysteine ​​and mix well. React in the dark for 22 hours. After dialysis and drying, thiolated chitosan is obtained. Mix 5 parts of polyvinyl alcohol and 200 parts of 1wt% boric acid aqueous solution evenly, add 5 parts of matrix and 2.5 parts of mercapto chitosan, stir evenly, then add 250 parts of 2wt% calcium chloride aqueous solution, stir for 2 hours, let stand for 12 hours, wash with water and anhydrous ethanol, and dry to obtain the aminated matrix. Step 3: Mix 40wt% NaOH aqueous solution and carbon disulfide evenly, add 5 parts of aminated matrix, react at 20℃ for 20 min, then transfer to a 40℃ water bath to continue the reaction for 4 h, cool to room temperature, filter, wash and dry to obtain modified biochar. The preparation method of modified clay is as follows: 30 parts of clay were dispersed in a mixed solution of 300 parts of anhydrous ethanol and 60 parts of deionized water. 9 parts of 3-aminopropyltriethoxysilane were added and mixed evenly. The pH of the system was adjusted to 4 using glacial acetic acid. The mixture was reacted at 60°C for 2 hours. After filtration, centrifugation, and drying, modified clay was obtained.

[0022] Example 2: A preparation process for an environmentally friendly brick carving blank, comprising the following processes: Step 1: Mix 45 parts waste concrete, 35 parts steel slag powder, 15 parts fly ash, 10 parts modified biochar, and 35 parts modified clay evenly to obtain a mixed solid. Step 2: Pour 40 parts of water into the mixed solids and stir well. Then add 5 parts of cement and 0.3 parts of water-reducing agent and stir well to obtain a mixed slurry. After pressing the mixed slurry into shape, demold it to obtain an environmentally friendly brick carving blank. The preparation method of modified biochar is as follows: Step 1: After dewatering, drying, crushing, and passing 10 parts of sludge through a 100-mesh sieve, the sludge is heated to 650℃ at 4℃ / min under a nitrogen atmosphere and held for 2.5h. After naturally cooling to room temperature, it is washed with water and anhydrous ethanol to obtain sludge biochar. 15 parts ZnCl2 were dissolved in 500 parts deionized water, 10 parts sludge biochar were added, nitrogen gas was passed through to remove oxygen for 35 min, and 525 parts 0.36 mol / L sodium borohydride aqueous solution were added dropwise under stirring at room temperature, which was completed in 1.5 h. After reacting for 23 h, the matrix was obtained by centrifugation, washing with water and anhydrous ethanol, and drying. Step 2: Disperse 5 parts of chitosan in 500 parts of deionized water, add 1 mol / L hydrochloric acid to adjust the pH to 6.5, then add 37 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 21 parts of N-hydroxysuccinimide and 15 parts of L-cysteine ​​and mix well. React in the dark for 23 hours. After dialysis and drying, thiolated chitosan is obtained. Mix 6 parts of polyvinyl alcohol and 270 parts of 2wt% boric acid aqueous solution evenly, add 10 parts of matrix and 4.8 parts of mercapto chitosan, stir evenly, then add 480 parts of 3wt% calcium chloride aqueous solution, stir for 2.5 h, let stand for 22 h, wash with water and anhydrous ethanol, and dry to obtain aminated matrix. Step 3: Mix 120 parts of 45wt% NaOH aqueous solution and 15 parts of carbon disulfide evenly, add 10 parts of aminated matrix, react at 25℃ for 30 min, then transfer to a 45℃ water bath to continue the reaction for 6 h, cool to room temperature, filter, wash and dry to obtain modified biochar. The preparation method of modified clay is as follows: 35 parts of clay were dispersed in a mixed solution of 400 parts of anhydrous ethanol and 105 parts of deionized water. 14 parts of 3-aminopropyltriethoxysilane were added and mixed evenly. The pH of the system was adjusted to 4.5 with glacial acetic acid. The mixture was reacted at 65°C for 3 hours. After filtration, centrifugation and drying, modified clay was obtained.

[0023] Example 3: A preparation process for an environmentally friendly brick carving blank, comprising the following processes: Step 1: Mix 50 parts waste concrete, 40 parts steel slag powder, 20 parts fly ash, 15 parts modified biochar, and 40 parts modified clay evenly to obtain a mixed solid. Step 2: Pour 50 parts of water into the mixed solids and stir well. Then add 8 parts of cement and 0.5 parts of water-reducing agent and stir well to obtain a mixed slurry. After pressing the mixed slurry into shape, demold it to obtain an environmentally friendly brick carving blank. The preparation method of modified biochar is as follows: Step 1: After dewatering, drying, crushing, and passing the sludge through a 100-mesh sieve, the sludge is heated to 700℃ at 5℃ / min under a nitrogen atmosphere and held for 3 hours. After naturally cooling to room temperature, it is washed with water and anhydrous ethanol to obtain sludge biochar. 18.75 parts ZnCl2 were dissolved in 750 parts deionized water, 15 parts sludge biochar were added, nitrogen gas was purged for deoxygenation for 40 min, and 750 parts 0.4 mol / L sodium borohydride aqueous solution was added dropwise under stirring at room temperature over 2 h. After reacting for 24 h, the matrix was obtained by centrifugation, washing with water and anhydrous ethanol, and drying. Step 2: Disperse 7.5 parts of chitosan in 750 parts of deionized water, add 1 mol / L hydrochloric acid to adjust the pH to 7, then add 60 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 33 parts of N-hydroxysuccinimide and 30 parts of L-cysteine ​​and mix well. React in the dark for 24 hours. After dialysis and drying, thiolated chitosan is obtained. Mix 7.5 parts of polyvinyl alcohol and 375 parts of 3wt% boric acid aqueous solution evenly, add 15 parts of matrix and 7.5 parts of mercapto chitosan, stir evenly, then add 750 parts of 4wt% calcium chloride aqueous solution, stir for 3 hours, let stand for 24 hours, wash with water and anhydrous ethanol, and dry to obtain aminated matrix. Step 3: Mix 225 parts of 50wt% NaOH aqueous solution and 30 parts of carbon disulfide evenly, add 15 parts of aminated matrix, react at 30℃ for 40 min, then transfer to a 50℃ water bath to continue the reaction for 8 h, cool to room temperature, filter, wash and dry to obtain modified biochar. The preparation method of modified clay is as follows: 40 parts of clay were dispersed in a mixed solution of 480 parts of anhydrous ethanol and 160 parts of deionized water. 20 parts of 3-aminopropyltriethoxysilane were added and mixed evenly. The pH of the system was adjusted to 5 using glacial acetic acid. The mixture was reacted at 70°C for 4 hours. After filtration, centrifugation and drying, the modified clay was obtained.

[0024] Comparative Example 1: Comparative Example 1 is based on Example 2. It does not include step 3. The aminated matrix in step 2 is replaced with modified biochar. The remaining process steps and reaction parameters are the same as in Example 2. The preparation method of modified biochar is as follows: Step 1: After dewatering, drying, crushing, and passing 10 parts of sludge through a 100-mesh sieve, the sludge is heated to 650℃ at 4℃ / min under a nitrogen atmosphere and held for 2.5h. After naturally cooling to room temperature, it is washed with water and anhydrous ethanol to obtain sludge biochar. 15 parts ZnCl2 were dissolved in 500 parts deionized water, 10 parts sludge biochar were added, nitrogen gas was passed through to remove oxygen for 35 min, and 525 parts 0.36 mol / L sodium borohydride aqueous solution were added dropwise under stirring at room temperature, which was completed in 1.5 h. After reacting for 23 h, the matrix was obtained by centrifugation, washing with water and anhydrous ethanol, and drying. Step 2: Disperse 5 parts of chitosan in 500 parts of deionized water, add 1 mol / L hydrochloric acid to adjust the pH to 6.5, then add 37 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 21 parts of N-hydroxysuccinimide and 15 parts of L-cysteine ​​and mix well. React in the dark for 23 hours. After dialysis and drying, thiolated chitosan is obtained. Six parts of polyvinyl alcohol and 270 parts of 2wt% boric acid aqueous solution were mixed evenly, 10 parts of matrix and 4.8 parts of mercapto chitosan were added, and the mixture was stirred evenly. Then, 480 parts of 3wt% calcium chloride aqueous solution were added, and the mixture was stirred for 2.5 hours. After standing for 22 hours, the modified biochar was obtained after washing with water and anhydrous ethanol and drying.

[0025] Comparative Example 2: Comparative Example 2 is based on Example 2, but without the introduction of thiol chitosan. The remaining process steps and reaction parameters are the same as in Example 2. The preparation method of modified biochar is as follows: Step 1: After dewatering, drying, crushing, and passing 10 parts of sludge through a 100-mesh sieve, the sludge is heated to 650℃ at 4℃ / min under a nitrogen atmosphere and held for 2.5h. After naturally cooling to room temperature, it is washed with water and anhydrous ethanol to obtain sludge biochar. 15 parts ZnCl2 were dissolved in 500 parts deionized water, 10 parts sludge biochar were added, nitrogen gas was passed through to remove oxygen for 35 min, and 525 parts 0.36 mol / L sodium borohydride aqueous solution were added dropwise under stirring at room temperature, which was completed in 1.5 h. After reacting for 23 h, the matrix was obtained by centrifugation, washing with water and anhydrous ethanol, and drying. Step 2: Mix 6 parts of polyvinyl alcohol and 270 parts of 2wt% boric acid aqueous solution evenly, add 10 parts of matrix and stir evenly, then add 480 parts of 3wt% calcium chloride aqueous solution, stir for 2.5 hours, let stand for 22 hours, wash with water and anhydrous ethanol, and dry to obtain intermediate. Step 3: Mix 120 parts of 45wt% NaOH aqueous solution and 15 parts of carbon disulfide evenly, add 10 parts of intermediate, react at 25℃ for 30 min, then transfer to a 45℃ water bath to continue the reaction for 6 h, cool to room temperature, filter, wash and dry to obtain modified biochar.

[0026] Comparative Example 3: Comparative Example 3 is based on Example 2, except that the modified biochar is replaced with the same mass of biochar, and the remaining process steps and reaction parameters are the same as in Example 2.

[0027] Experiment: The environmentally friendly brick carving blanks obtained in Examples 1-3 and Comparative Examples 1-3 were dried to a moisture content of 25% and then fired in a brick kiln at 1000℃ for 12 hours to obtain environmentally friendly brick carvings, i.e., samples. Their performance was tested and the test results were recorded: 1. The compressive strength was determined according to the national standard GB / T5101-2017 "Sintered Common Bricks". During the test, the pressure rate was kept at 1.5 mm / min and the pressure was continuously applied until the brick was destroyed. The pressure at this time was recorded and three parallel tests were conducted.

[0028] 2. The permeability performance was determined according to GB / T 25993-2010 "Permeable Pavement Bricks and Permeable Pavement Panels". The experimental procedure was as follows: A Φ75mm × 40mm cylinder was prepared from the product as a sample. The upper surface area A of the cylinder was calculated and determined. The cylinder was sealed with sealant around its perimeter to prevent leakage, allowing water to permeate only from the top and bottom surfaces. The prepared cylinder was placed in an overflow trough, and water was added, controlling the water flow rate and volume to ensure water could pass through both the upper and lower surfaces of the cylinder, maintaining a stable water level difference between the test cylinder and the overflow trough. The water volume Q was calculated over a certain time period (300s in this experiment). After three tests, the average value was taken. The water level difference H between the permeable cylinder and the overflow trough was then measured with a ruler, accurate to 0.1cm.

[0029] The test results are shown in Table 1.

[0030] Table 1. Test results of relevant performance of environmentally friendly brick carvings Based on the data in the table above, the following conclusions can be clearly drawn: The environmentally friendly brick carvings prepared by this invention have excellent mechanical and permeability properties. Compared with Examples 1-3, the compressive strength and permeability coefficient of the products obtained in Comparative Examples 1, 2 and 3 all decreased, indicating that by introducing dithiocarboxyl groups (-C(=S)-S-) and thiol chitosan, this invention forms a "double sulfur synergistic" reinforcing network inside the material, increasing the interaction force between materials and thus improving the mechanical properties of the material. Compared with ordinary biochar, the modified biochar prepared by this invention has abundant functional groups (such as carboxyl, amino, thiol and dithiocarboxyl groups) introduced on its surface, which greatly improves the interfacial bonding force with matrices such as clay, waste concrete, and steel slag powder.

[0031] 3. Take the samples prepared in Example 2 and Comparative Examples 1-2, and immerse them in the prepared aqueous solution containing contaminants (COD: 258 mg / L, NH4+). + -N: 6.17mg / L, TP: 10.86mg / L, Pb 2+ 3.56 mg / L, Cd 2+ 3.34 mg / L, Cu 2+(1.18 mg / L), then placed in a constant temperature shaker for 120 hours of shaking, filtered, and the filtrate was used to determine the concentration of pollutants, COD, NH4+. + -N and TP were detected using the acidic potassium dichromate digestion titration method, Nessler's reagent spectrophotometry, and potassium persulfate digestion-ammonium molybdate spectrophotometry, respectively. Pb 2+ Cd 2+ Cu 2+ The content was determined using a TAS-990 atomic absorption spectrophotometer.

[0032] Table 2. Test results of pollutant removal rate of environmentally friendly brick carvings. Based on the data in the table above, the following conclusions can be clearly drawn: the environmentally friendly brick carving prepared by this invention has an adsorption effect on heavy metals, which can effectively remove heavy metal ions from water bodies and reduce environmental pollution.

[0033] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A preparation process for an environmentally friendly brick carving blank, characterized in that: Includes the following steps: Step 1: Mix waste concrete, steel slag powder, fly ash, modified biochar, and modified clay evenly to obtain a mixed solid. Step 2: Pour water into the mixed solids and stir evenly, then add cement and water-reducing agent and stir evenly to obtain a mixed slurry; press the mixed slurry into shape, demold it, and obtain the environmentally friendly brick carving blank.

2. The preparation process of an environmentally friendly brick carving blank according to claim 1, characterized in that: The environmentally friendly brick carving blank material includes the following weight components: 40-50 parts waste concrete, 30-40 parts steel slag powder, 10-20 parts fly ash, 5-15 parts modified biochar, 3-8 parts cement, 30-40 parts modified clay, 30-50 parts water, and 0.2-0.5 parts water-reducing agent.

3. The preparation process of an environmentally friendly brick carving blank according to claim 2, characterized in that: The method for preparing the modified biochar is as follows: Step 1: Dissolve ZnCl2 in deionized water, add sludge biochar, purge with nitrogen to remove oxygen for 30-40 min, add sodium borohydride aqueous solution dropwise under stirring at room temperature, complete the addition in 1-2 h, react for 22-24 h, centrifuge, wash with water, wash with anhydrous ethanol, dry to obtain the matrix; Step 2: Mix polyvinyl alcohol and boric acid aqueous solution evenly, add matrix and mercapto chitosan, stir evenly, then add calcium chloride aqueous solution, stir for 2-3 hours, let stand for 12-24 hours, wash with water and anhydrous ethanol, and dry to obtain aminated matrix; Step 3: Mix NaOH aqueous solution and carbon disulfide evenly, add aminated matrix, react at 20-30℃ for 20-40 min, then transfer to a water bath at 40-50℃ to continue the reaction for 4-8 h, cool to room temperature, filter, wash and dry to obtain modified biochar.

4. The preparation process of an environmentally friendly brick carving blank according to claim 3, characterized in that: The method for preparing the sludge biochar is as follows: After dewatering, drying, crushing, and passing through a 100-mesh sieve, the sludge is heated to 600-700℃ at a rate of 3-5℃ / min under a nitrogen atmosphere and held for 2-3 hours. It is then naturally cooled to room temperature and washed with water and anhydrous ethanol to obtain sludge biochar.

5. The preparation process of an environmentally friendly brick carving blank according to claim 3, characterized in that: In step 2, the mass ratio of polyvinyl alcohol, boric acid aqueous solution, matrix and thiol chitosan is 1:(40-50):(1-2):(0.5-1.0), and the concentration of boric acid aqueous solution is 1-3wt%.

6. The preparation process of an environmentally friendly brick carving blank according to claim 5, characterized in that: The method for preparing the thiolized chitosan is as follows: Chitosan was dispersed in deionized water, and hydrochloric acid was added to adjust the pH to 6-7. Then, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide and L-cysteine ​​were added and mixed evenly. The mixture was reacted in the dark for 22-24 hours. After dialysis and drying, thiolated chitosan was obtained.

7. The preparation process of an environmentally friendly brick carving blank according to claim 3, characterized in that: The mass ratio of the aminated matrix, NaOH aqueous solution and carbon disulfide is 1:(10-15):(1-2), and the concentration of the NaOH aqueous solution is 40-50wt%.

8. The preparation process of an environmentally friendly brick carving blank according to claim 1, characterized in that: The modified clay is prepared as follows: Clay was dispersed in a mixed solution of anhydrous ethanol and deionized water, and 3-aminopropyltriethoxysilane was added and mixed evenly. The pH of the system was adjusted to 4-5 using glacial acetic acid, and the reaction was carried out at 60-70℃ for 2-4 hours. After filtration, centrifugation and drying, modified clay was obtained.

9. The preparation process of an environmentally friendly brick carving blank according to claim 8, characterized in that: The mass ratio of the clay to anhydrous ethanol, deionized water, and 3-aminopropyltriethoxysilane is 1:(10-12):(2-4):(0.3-0.5).

10. An environmentally friendly brick carving blank prepared by the preparation method according to any one of claims 1-9.

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