Semi-coke wastewater-based phenolic resin porous carbon adsorption material and preparation method thereof

Abstract

The invention discloses a semi-coke wastewater-based phenolic resin porous carbon adsorption material and a preparation method thereof, high-pollution semi-coke wastewater is used as a phenol source, waste potato residues are used as a modifier, and the semi-coke wastewater is subjected to composite flocculation, macroporous adsorption resin adsorption elution and reduced pressure distillation concentration to obtain a phenol-rich solution; carrying out alkaline hydrolysis-oxidation-silane coupling agent graded modification on the potato residues; the preparation method comprises the following steps: polymerizing a phenol-rich solution with furfural, compounding with graded modified potato residues, carrying out in-situ crosslinking with urotropine, carbonizing, and carrying out ZnCl2-citric acid composite activation to finally prepare the semi-coke wastewater-based phenolic resin porous carbon adsorption material. According to the method, the potato residues and the semi-coke wastewater are synergistically recycled, the material is endowed with high specific surface area, a multi-stage pore channel structure and rich surface functional groups through compound modification, graded modification and graded carbonization, the potato residues are completely recycled, the process is free of secondary pollution, the cost is reduced by 30%-40%, and the method can be widely applied to the fields of industrial wastewater treatment, atmospheric pollutant adsorption and the like. The environment-friendly and economic values are realized.

Description

Technical Field

[0001] This invention belongs to the field of coal chemical wastewater resource utilization and porous carbon material preparation technology, specifically involving a porous carbon adsorbent material and its preparation method using semi-coke wastewater and potato residue as raw materials. Background Technology

[0002] The semi-coke industry is an important component of my country's coal grading and utilization, but the production process generates a large amount of high-concentration organic wastewater—semi-coke wastewater. This type of wastewater has a complex composition, containing high concentrations of volatile phenols, polyphenols, ammonia nitrogen, and tar, among other pollutants. Phenolic compounds are highly toxic and difficult to degrade; direct discharge can cause serious damage to the ecological environment. Traditional semi-coke wastewater treatment methods mainly include solvent extraction for phenol removal, biochemical treatment, and advanced oxidation, but these methods suffer from problems such as long processes, high operating costs, low resource recovery rates, and the potential for secondary pollution.

[0003] Porous carbon materials, due to their large specific surface area, well-developed pore structure, and good chemical stability, are widely used in water treatment, gas separation, and catalyst supports. In existing technologies, porous carbon materials mostly use coal, wood, or synthetic resins as raw materials, resulting in high costs and complex preparation processes. Utilizing phenol-rich semi-coke wastewater directly as a carbon source precursor, and preparing porous carbon materials through polymerization and carbonization, not only achieves the resource utilization of phenolic pollutants in wastewater but also significantly reduces the production cost of porous carbon materials, demonstrating significant economic and environmental benefits. However, existing technologies lack efficient modification methods to improve their adsorption performance.

[0004] Potato residue is a major byproduct of potato starch processing. It is rich in starch, cellulose and a small amount of nitrogenous components. Currently, it is mostly treated as feed or waste, and its high-value utilization is limited. Summary of the Invention

[0005] The purpose of this invention is to provide a porous carbon adsorbent material based on phenolic resin for semi-coke wastewater and its preparation method, which solves the problems of low resource utilization rate of semi-coke wastewater, waste of potato residue, single pore structure of porous carbon materials, and insufficient adsorption performance in the prior art, and achieves the unity of "co-resource utilization of wastewater and waste residue" and "high performance of adsorbent materials".

[0006] To achieve the above-mentioned objectives, the preparation method of the porous carbon adsorbent material based on semi-coke wastewater phenolic resin provided by the present invention includes the following steps:

[0007] Step 1: The semi-coke wastewater is subjected to flocculation with a composite flocculant, adsorption and elution with a macroporous adsorption resin column, and concentration by vacuum distillation to obtain a phenol-rich solution with a phenol concentration of 40-80 g / L.

[0008] Step 2: Potato residue is successively modified by sodium hydroxide alkaline hydrolysis, hydrogen peroxide hydroxide modification, and silane coupling agent modification to obtain graded modified potato residue.

[0009] Step 3: The phenol-rich solution is polymerized with furfural, graded modified potato residue is added, and the mixture is cross-linked in situ with urotropine, dried, and pulverized to obtain composite resin powder.

[0010] Step 4: The composite resin powder is carbonized, activated by ZnCl2-citric acid composite, acid washed, washed with water, and dried to obtain a semi-coke wastewater-based phenolic resin porous carbon adsorbent material.

[0011] Further, in step 1 above, 5%–10% (w / w) of a composite flocculant is added to the semi-coke wastewater, and flocculation is carried out at 25–35°C and a stirring rate of 200–300 r / min for 30–60 min. After settling, the supernatant is collected. The supernatant is then passed through a macroporous adsorption resin column (model D101) at a flow rate of 1–2 BV / h. After adsorption saturation, the column is eluted with a 10%–15% (w / w) ethanol aqueous solution. The eluent is collected and concentrated under reduced pressure by distillation to a phenol concentration of 40–80 g / L to obtain a phenol-rich solution. The composite flocculant is a mixture of polyaluminum chloride and chitosan in a mass ratio of 2–4:1.

[0012] Further, in step 2 above, the potato residue is washed, dried, pulverized, and then passed through a 100-mesh sieve to obtain potato residue powder. The drying conditions are 80–100℃ for 4–6 hours. The potato residue powder is added to an 8%–12% sodium hydroxide aqueous solution, wherein the liquid-to-solid ratio of the sodium hydroxide aqueous solution to the potato residue is 5–15 mL:1 g. The mixture is stirred and reacted at 60–80℃ for 2–3 hours, filtered, and washed until neutral to obtain alkali-modified residue. This alkali-modified residue is a primary potato modified residue, the purpose of which is to break down the cellulose crystalline structure and expose the hydroxyl groups.

[0013] Further, in step 2 above, the alkaline-modified residue is added to a 5%–8% (w / w) hydrogen peroxide aqueous solution, wherein the liquid-to-solid ratio of the hydrogen peroxide aqueous solution to the potato residue is 5–12 mL:1 g. The pH is adjusted to 3–4 with a 5%–10% (w / w) hydrochloric acid aqueous solution, and the mixture is ultrasonically reacted at 40–50°C for 1–2 hours with an ultrasonic power of 300–400 W. After filtration, washing, and drying, the oxidized modified residue is obtained. This oxidized modified residue is a secondary potato modified residue, the purpose of which is to introduce active groups such as carboxyl and carbonyl groups.

[0014] Further, in step 2 above, the oxidized modified residue is mixed with an ethanol solution of 3%–5% by mass of a silane coupling agent, wherein the silane coupling agent is KH-550 or KH-560, and the liquid-to-solid ratio of the ethanol solution of the silane coupling agent to the potato residue is 4–10 mL:1 g. The mixture is refluxed at 70–80 °C for 1–1.5 h, filtered, and dried to obtain graded modified potato residue. This graded modified potato residue is a three-stage modified potato residue, the purpose of which is to improve its compatibility with phenolic resin.

[0015] Further, in step 3 above, furfural is added to the phenol-rich solution, with a furfural to phenol mass ratio of 1 to 2:1. The pH is adjusted to 8 to 9 with a 10% to 20% sodium hydroxide aqueous solution, and the mixture is stirred at 90 to 105°C for 30 to 45 minutes to obtain primary phenolic resin.

[0016] Further, in step 3 above, graded modified potato residue is added to the primary phenolic resin. The amount of graded modified potato residue added is 20%–40% of the phenol mass. The mixture is stirred and reacted at 80–90°C for 2–3 hours. During this period, a 5%–8% (w / w) aqueous solution of hexamethylenetetramine is added in three portions, with the total amount of hexamethylenetetramine being 10%–15% of the phenol mass, to achieve in-situ crosslinking and obtain a gel-like composite resin. The gel-like composite resin is then vacuum-dried at 60–70°C for 12–16 hours and pulverized through a 100-mesh sieve to obtain composite resin powder.

[0017] Further, in step 4 above, the composite resin powder is heated to 300-400℃ at a rate of 5-8℃ / min under nitrogen protection and held for 1-1.5h to remove volatile impurities, obtaining primary carbonized material; a ZnCl2-citric acid composite activator is added to the primary carbonized material and mixed evenly, wherein the mass ratio of ZnCl2 to citric acid in the composite activator is 3:1, and its amount is 80%-120% of the mass of the primary carbonized material, and then the temperature is increased to 600℃ at a rate of 3-5℃ / min. The material is initially pore-forming by holding at 00–700℃ for 2–2.5 h; then, it is heated to 800–880℃ at a rate of 2–3℃ / min and held for 1–1.5 h to promote the synergistic formation of micropores and mesopores; subsequently, it is cooled to room temperature at a rate of 2–4℃ / min, washed with a 5%–10% hydrochloric acid aqueous solution until no bubbles are generated, then washed with deionized water until neutral, and dried at 100–110℃ for 4–6 h to obtain a porous carbon adsorbent material based on semi-coke wastewater phenolic resin.

[0018] The beneficial effects of this invention are as follows:

[0019] This invention utilizes potato residue and semi-coke wastewater as raw materials to prepare novel porous carbon materials with excellent performance through a synergistic resource utilization process. For semi-coke wastewater, an integrated process of "phenol enrichment-in-situ crosslinking-gradient carbonization activation" was developed. This process not only improves the crosslinking degree of phenolic resin, achieving tight bonding at the molecular level, but also precisely controls the micropore to mesopore ratio of the carbon material, effectively overcoming the limitations of the single pore structure of traditional porous carbon materials. For potato residue, an innovative three-stage treatment process of "alkali hydrolysis-oxidation-silane coupling" was adopted, sequentially breaking down the cellulose structure, introducing active functional groups, and significantly improving material compatibility, thus solving the problems of weak bonding and unstable performance in traditional single modification methods. The treated potato residue is transformed into a highly active modifier for precisely controlling the polymerization and carbonization process of phenolic resin. Ultimately, a novel porous carbon material with high specific surface area, hierarchical pore structure, and rich surface chemical properties was successfully constructed. The entire preparation process achieves high-value utilization of two types of waste, with no secondary pollution, and has significant advantages of low cost and environmental friendliness. Attached Figure Description

[0020] Figure 1 This is a SEM image of the porous carbon adsorbent material based on phenolic resin for semi-coke wastewater prepared in Example 1.

[0021] Figure 2 The porous carbon adsorbent material based on phenolic resin for semi-coke wastewater prepared in Example 1 and Comparative Examples 1-5 is used for Cr... 6+ Adsorption effect comparison chart.

[0022] Figure 3 This is a comparison chart showing the adsorption effect of methylene blue on the porous carbon adsorbent material based on phenolic resin for semi-coke wastewater prepared in Example 1 and Comparative Examples 1-5. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It is obvious that the described embodiments are only some examples of the present invention, and not all of them. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0024] Unless otherwise specified, all raw materials, reagents, instruments and equipment involved in this invention can be purchased from the market or prepared according to existing technical methods.

[0025] Example 1

[0026] Step 1: Take 1L of semi-coke wastewater (from a coking plant in Shaanxi Province), add 70g of composite flocculant (52.5g of polyaluminum chloride + 17.5g of chitosan), stir and flocculate at 250r / min at 30℃ for 45min, let stand, take the supernatant, pass it through a D101 macroporous adsorption resin column (flow rate 1.5BV / h), after adsorption saturation, elute with 12% ethanol aqueous solution, collect the eluent, and concentrate it by pressure distillation to a phenol concentration of 80g / L to obtain a phenol-rich solution.

[0027] Step 2: Wash the potato residue with water and dry it at 80℃ for 5 hours. Crush it and pass it through a 100-mesh sieve. Take 100g of powder and add it to 1000mL of 10% sodium hydroxide aqueous solution. Stir at 70℃ for 2.5 hours. After filtration, wash it with deionized water until neutral to obtain alkaline modified residue. Then add 800mL of 6% hydrogen peroxide aqueous solution and adjust the pH to 3.5 with 8% hydrochloric acid aqueous solution. Sonicate it at 45℃ for 1.5 hours with an ultrasonic power of 350W. After filtration, wash it with deionized water until neutral to obtain oxidized modified residue. Finally, add 600mL of 4% ethanol solution of silane coupling agent KH-550 and reflux it at 75℃ for 1.2 hours. After filtration, dry it at 80℃ for 5 hours to obtain graded modified potato residue.

[0028] Step 3: Take 500 mL of the phenol-rich solution obtained in Step 1, add 150 g of 40% furfural aqueous solution, adjust the pH to 8.5 with 15% sodium hydroxide aqueous solution, stir and react at 100℃ for 40 min to obtain primary phenolic resin; then add 12 g of graded modified potato residue, stir and react at 85℃ for 2.5 h, during which time 80 g of 6% hexamethylenetetramine aqueous solution is added in 3 portions to obtain gel-like composite resin; vacuum dry the gel-like composite resin at 65℃ for 14 h, pulverize it through a 100-mesh sieve to obtain composite resin powder.

[0029] Step 4: Under N2 protection, 40g of the composite resin powder obtained in Step 3 is heated to 350℃ at 6℃ / min and held for 1.2h to obtain primary carbon. Then, 40g of composite activator (30g ZnCl2 + 10g citric acid) is added and mixed evenly. The mixture is then heated to 650℃ at 4℃ / min and held for 2.2h. The temperature is then increased to 850℃ at 2.5℃ / min and held for 1.2h. The mixture is then cooled to room temperature at a rate of 3℃ / min. After washing with 7% hydrochloric acid aqueous solution, the mixture is washed with deionized water until neutral. The mixture is then dried at 105℃ for 5h to obtain semi-coke wastewater-based phenolic resin porous carbon adsorbent material.

[0030] like Figure 1As shown in the image, a three-dimensional network of micropores and mesopores is visible, with no obvious pore collapse or blockage. The pore connectivity is excellent, with no isolated or closed pores. After graded modification, potato residue achieves molecular-level bonding with phenolic resin. The silane coupling agent improves compatibility, causing the cellulose skeleton of the potato residue to form a "supported rough surface" after carbonization, which significantly increases the specific surface area and adsorption sites. No obvious cracks, fractures, or agglomerations were observed in the image, proving the effectiveness of "in-situ crosslinking of hexamethylenetetramine + controlled cooling". The three-dimensional network structure formed by crosslinking and slow cooling avoid thermal stress damage, making the mechanical strength of the carbon material stable and less prone to pulverization during the adsorption-desorption cycle. The carbon skeleton is a continuous network without obvious impurity agglomerates, indicating that the steps of phenol enrichment and acid washing purification in semi-coke wastewater effectively remove impurities, ensuring the purity and pore quality of the material.

[0031] Comparative Example 1

[0032] Step 1: This step is the same as step 1 in Example 1.

[0033] Step 2: Wash the potato residue with water and dry it at 80℃ for 5 hours. Crush it and pass it through a 100-mesh sieve. Take 100g of powder and add it to 1000mL of 10% sodium hydroxide aqueous solution. Stir at 70℃ for 2.5 hours. After filtration, wash it with deionized water until neutral to obtain alkaline modified residue.

[0034] Step 3: In this step, the graded modified potato residue in Step 3 of Example 1 is replaced with an equal mass of alkaline modified potato residue. The other steps are the same as in Step 3 of Example 1, and the composite resin powder is obtained.

[0035] Step 4: This step is the same as step 4 in Example 1, to obtain a porous carbon adsorbent material based on semi-coke wastewater phenolic resin.

[0036] Comparative Example 2

[0037] Step 1: This step is the same as step 1 in Example 1.

[0038] Step 2: This step is the same as step 2 in Example 1.

[0039] Step 3: This step is the same as step 2 in Example 1.

[0040] Step 4: In this step, the composite activator in Step 4 of Example 1 is replaced with an equal mass of ZnCl2. The other steps are the same as in Step 4 of Example 1, and a porous carbon adsorbent material based on semi-coke wastewater phenolic resin is obtained.

[0041] Comparative Example 3

[0042] Step 1: This step is the same as step 1 in Example 1.

[0043] Step 2: This step is the same as step 2 in Example 1.

[0044] Step 3: This step is the same as step 2 in Example 1.

[0045] Step 4: The composite resin powder obtained in Step 3 is heated to 850℃ at 5℃ / min under N2 protection and kept at that temperature for 3h. Then it is cooled to room temperature at a rate of 3℃ / min to obtain a semi-coke wastewater-based phenolic resin porous carbon adsorbent material.

[0046] Comparative Example 4

[0047] Step 1: This step is the same as step 2 in Example 1.

[0048] Step 2: In this step, the phenol-rich solution in Step 3 of Example 1 is replaced with semi-coke wastewater, and the molar ratio of furfural to phenol is controlled at 1.5:1. The other steps are the same as in Step 3 of Example 1, and composite resin powder is obtained.

[0049] Step 3: This step is the same as step 4 in Example 1, to obtain a porous carbon adsorbent material based on semi-coke wastewater phenolic resin.

[0050] Comparative Example 5

[0051] Step 1: This step is the same as step 1 in Example 1.

[0052] Step 2: This step is the same as step 2 in Example 1.

[0053] Step 3: Add 40% furfural aqueous solution (molar ratio of furfural to phenol 1.5:1), adjust the pH to 8.5 with 15% sodium hydroxide aqueous solution, stir and react at 100℃ for 40 min to obtain primary phenolic resin; then add 30g of graded modified potato residue, stir and react at 85℃ for 2.5 h, cool to room temperature, vacuum dry at 65℃ for 14 h, pulverize and pass through a 100-mesh sieve to obtain composite resin powder.

[0054] Step 4: This step is the same as step 4 in Example 1, to obtain a porous carbon adsorbent material based on semi-coke wastewater phenolic resin.

[0055] Example 2

[0056] Step 1: Take 1L of semi-coke wastewater (from a coking plant in Shaanxi Province), add 60g of composite flocculant (40g of polyaluminum chloride + 20g of chitosan), stir and flocculate at 250r / min at 30℃ for 60min, let stand, take the supernatant, pass it through a D101 macroporous adsorption resin column (flow rate 1BV / h), after adsorption saturation, elute with 10% ethanol aqueous solution, collect the eluent, and concentrate it by pressure distillation to a phenol concentration of 50g / L to obtain a phenol-rich solution.

[0057] Step 2: Wash the potato residue with water and dry it at 80℃ for 5 hours. Crush it and pass it through a 100-mesh sieve. Take 100g of powder and add it to 1500mL of 8% sodium hydroxide aqueous solution. Stir at 80℃ for 2 hours. After filtration, wash it with deionized water until neutral to obtain alkaline modified residue. Then add 500mL of 8% hydrogen peroxide aqueous solution and adjust the pH to 3.5 with 8% hydrochloric acid aqueous solution. Sonicate at 45℃ for 1.5 hours with ultrasonic power of 350W. After filtration, wash it with deionized water until neutral to obtain oxidized modified residue. Finally, add 800mL of 3% ethanol solution of silane coupling agent KH-550 and reflux at 75℃ for 1.2 hours. After filtration, dry it at 80℃ for 5 hours to obtain graded modified potato residue.

[0058] Step 3: Take 500 mL of the phenol-rich solution obtained in Step 1, add 94 g of 40% furfural aqueous solution, adjust the pH to 8.5 with 15% sodium hydroxide aqueous solution, and stir at 100℃ for 40 min to obtain primary phenolic resin; then add 8 g of graded modified potato residue, stir at 85℃ for 2.5 h, and during this period, add a total of 50 g of 6% hexamethylenetetramine aqueous solution in 3 portions to obtain gel-like composite resin; vacuum dry the gel-like composite resin at 65℃ for 14 h, pulverize it through a 100-mesh sieve to obtain composite resin powder.

[0059] Step 4: Under N2 protection, 50g of the composite resin powder obtained in Step 3 is heated to 350℃ at 6℃ / min and held for 1.2h to obtain primary carbon. Then, 40g of composite activator (30g ZnCl2 + 10g citric acid) is added and mixed evenly. The mixture is then heated to 650℃ at 4℃ / min and held for 2.2h. The temperature is then increased to 850℃ at 2.5℃ / min and held for 1.2h. The mixture is then cooled to room temperature at a rate of 3℃ / min. The mixture is washed with 7% hydrochloric acid aqueous solution and then washed with deionized water until neutral. Finally, it is dried at 105℃ for 5h to obtain a semi-coke wastewater-based phenolic resin porous carbon adsorbent material.

[0060] Example 3

[0061] Step 1: Take 1L of semi-coke wastewater (from a coking plant in Shaanxi Province), add 90g of composite flocculant (72g of polyaluminum chloride + 18g of chitosan), stir and flocculate at 250r / min at 30℃ for 30min, let stand, take the supernatant, pass it through a D101 macroporous adsorption resin column (flow rate 2BV / h), after adsorption saturation, elute with 15% ethanol aqueous solution, collect the eluent, and concentrate it by pressure distillation to a phenol concentration of 60g / L to obtain a phenol-rich solution.

[0062] Step 2: Wash the potato residue with water and dry it at 80℃ for 5 hours. Crush it and pass it through a 100-mesh sieve. Take 100g of powder and add it to 500mL of 12% sodium hydroxide aqueous solution. Stir at 60℃ for 3 hours. After filtration, wash it with deionized water until neutral to obtain alkaline modified residue. Then add 500mL of 10% hydrogen peroxide aqueous solution and adjust the pH to 3.5 with 8% hydrochloric acid aqueous solution. Sonicate it at 45℃ for 1.5 hours with an ultrasonic power of 350W. After filtration, wash it with deionized water until neutral to obtain oxidized modified residue. Finally, add 500mL of 5% ethanol solution of silane coupling agent KH-550 and reflux it at 75℃ for 1.2 hours. After filtration, dry it at 80℃ for 5 hours to obtain graded modified potato residue.

[0063] Step 3: Take 500 mL of the phenol-rich solution obtained in Step 1, add 113 g of 40% furfural aqueous solution, adjust the pH to 8.5 with 15% sodium hydroxide aqueous solution, and stir at 100℃ for 40 min to obtain primary phenolic resin; then add 9 g of graded modified potato residue, stir at 85℃ for 2.5 h, and during this period, add a total of 60 g of 6% hexamethylenetetramine aqueous solution in 3 portions to obtain gel-like composite resin; vacuum dry the gel-like composite resin at 65℃ for 14 h, pulverize it through a 100-mesh sieve to obtain composite resin powder.

[0064] Step 4: Under N2 protection, 50g of the composite resin powder obtained in Step 3 is heated to 350℃ at 6℃ / min and held for 1.2h to obtain primary carbon. Then, 60g of composite activator (45g ZnCl2 + 15g citric acid) is added and mixed evenly. The mixture is then heated to 650℃ at 4℃ / min and held for 2.2h. The temperature is then increased to 850℃ at 2.5℃ / min and held for 1.2h. The mixture is then cooled to room temperature at a rate of 3℃ / min. After washing with 7% hydrochloric acid aqueous solution, the mixture is washed with deionized water until neutral and dried at 105℃ for 5h to obtain semi-coke wastewater-based phenolic resin porous carbon adsorbent material.

[0065] The adsorption effect of the semi-coke wastewater-based phenolic resin porous carbon adsorbent materials prepared in Example 1 and Comparative Examples 1-5 was tested to evaluate their pore performance.

[0066] Test method: Add the adsorbent material at a dosage of 1 g / L to the Cr-containing... 6+ In simulated wastewater containing methylene blue (initial concentration 50 mg / L) and methylene blue (initial concentration 50 mg / L), adsorption was performed with shaking at room temperature for 2 hours. Cr was then determined by atomic absorption spectrophotometry. 6+ The concentration of methylene blue was determined by ultraviolet-visible spectrophotometry, and the removal rate and adsorption amount (mg / g) were calculated.

[0067] The test results are shown in Table 1 and Figures 2-3 As shown, all results are the average of three experiments.

[0068] Table 1. Comparison of Adsorption Effects

[0069]

[0070] From Table 1 and Figures 2-3 As can be seen, the porous carbon adsorbent material based on semi-coke wastewater prepared in Example 1 exhibits excellent adsorption performance, ideal pore structure, and stable carbon framework morphology, demonstrating optimal and stable adsorption performance. Compared to Example 1, the potato residue in Comparative Example 1 only underwent primary alkaline hydrolysis modification, without oxidation and silane coupling modification, resulting in Cr... 6+ The removal rate was 75.3%, and the adsorption capacity was 37.7 mg / g. The methylene blue removal rate was 72.1%, and the adsorption capacity was 36.1 mg / g, both of which were the lowest among all samples. This indicates that oxidation modification introduces active groups, enhances reactivity, and regulates surface affinity. Silane coupling agents can improve the compatibility between modified potato residue and phenolic resin, making the composite material structure more uniform, enhancing pore connectivity, and strengthening the exposure of adsorption sites. Without oxidation modification, there are insufficient active sites, poor compatibility and dispersibility, deteriorated pore structure, and a significant decrease in adsorption performance. Without silane coupling agent modification, the compatibility between potato residue and resin is poor, the structure is prone to agglomeration, pore blockage, and a reduction in adsorption sites. Comparative Example 2 used ZnCl2 as a single activator, and Cr... 6+ The removal rate was 86.3% and the adsorption capacity was 43.1 mg / g. The methylene blue removal rate was 84.5% and the adsorption capacity was 41.8 mg / g. Although these figures were higher than those of other comparative examples, the performance was still lower than that of Example 1. This indicates that the composite activator works synergistically. ZnCl2 creates pores, and citric acid regulates the surface charge, constructing a multi-level pore structure. At the same time, it increases the surface active functional groups, improving the adsorption capacity for ions and organic molecules. In contrast, the pore-creating effect of ZnCl2 alone is limited, and the number of surface functional groups is insufficient, resulting in a decrease in both the adsorption selectivity and capacity for pollutants. Comparative Example 3 used a single temperature of 850℃ for 3 hours for carbonization and activation. Cr 6+ The removal rate was 82.4%, and the adsorption capacity was 41.3 mg / g. The methylene blue removal rate was 80.3%, and the adsorption capacity was 40.2 mg / g. The performance was only at a medium level compared to the comparative examples. This indicates that gradient heating achieves stepwise impurity removal, initial pore formation, and synergistic formation of micropores and mesopores, avoiding pore collapse caused by rapid heating and ensuring the integrity of the pore structure and specific surface area. In contrast, single high-temperature carbonization easily leads to pore sintering and blockage, making it difficult to form a multi-level pore structure and reducing adsorption mass transfer efficiency. Comparative Example 4 directly used semi-coke wastewater to prepare phenolic resin without phenol enrichment treatment. Cr 6+The removal rate was 78.9%, and the adsorption capacity was 39.5 mg / g. The methylene blue removal rate was 76.4%, and the adsorption capacity was 38.2 mg / g, with performance only higher than Comparative Example 1. This indicates that pretreatment enriches phenols to remove impurities, providing high-purity raw materials for phenolic resin polymerization and ensuring the pore quality and adsorption activity of the material after subsequent carbonization. In contrast, wastewater contains many impurities and has a low phenol concentration, resulting in incomplete polymerization, numerous resin structural defects, and low porosity and poor adsorption performance of the carbonized material. Comparative Example 5 did not add hexamethylenetetramine when modifying phenolic resin with potato residue, and Cr... 6+ The removal rate was 84.6% and the adsorption capacity was 42.3 mg / g. The methylene blue removal rate was 82.5% and the adsorption capacity was 40.9 mg / g, which did not reach the performance level of Example 1. This indicates that hexamethylenetetramine, as a crosslinking agent, enables the phenolic resin and modified potato residue to form a stable three-dimensional network structure, improving the mechanical strength and thermal stability of the material. After carbonization, the pore structure is more stable. Without the use of a crosslinking agent, the material structure is loose, easily decomposes and collapses during carbonization, resulting in a large loss of pores and a significant decrease in adsorption performance.

[0071] In summary, this invention develops a porous carbon adsorbent material based on phenolic resin for semi-coke wastewater and its preparation method. Through a process of "phenol enrichment in semi-coke wastewater - graded modification of potato residue - in-situ crosslinking - gradient carbonization activation," the specific surface area, pore structure, and adsorption performance of the porous carbon material are significantly improved. It exhibits excellent removal effects for both heavy metal ions and organic pollutants. Simultaneously, it achieves the synergistic resource utilization of semi-coke wastewater and potato residue, with a green process and no secondary pollution, providing an innovative solution for industrial wastewater treatment.

Claims

1. A method for preparing a green liquor wastewater-based phenolic resin porous carbon adsorbent material, characterized in that, The method comprises the following steps: Step 1: the coking wastewater is flocculated by a composite flocculant, adsorbed and eluted by a macroporous adsorption resin column, and concentrated by vacuum distillation to obtain a phenol-rich solution with a phenol concentration of 40-80 g / L; Step 2: the potato residue is sequentially modified by sodium hydroxide alkaline hydrolysis, hydrogen peroxide oxidation, and silane coupling agent modification to obtain a hierarchically modified potato residue; Step 3: the phenol-rich solution is polymerized with furfural, and the hierarchically modified potato residue is added, then in-situ cross-linked by urotropine, dried, and crushed to obtain a composite resin powder; Step 4: the composite resin powder is carbonized, activated by ZnCl2-citric acid, pickled, washed with water, and dried to obtain a coking wastewater-based phenolic resin porous carbon adsorption material.

2. The method of claim 1, wherein the preparation of the semi-coke wastewater-based phenolic resin porous carbon adsorbent material is characterized by: In step 1, the composite flocculant is a mixture of polyaluminum chloride and chitosan with a mass ratio of 2-4:1, and the amount is 5%-10% of the mass of the coking wastewater; the flocculation temperature is 25-35℃, the stirring speed is 200-300 r / min, and the time is 30-60 min; the type of the macroporous adsorption resin column is D101, the loading flow rate is 1-2 BV / h, and after adsorption saturation, the eluent is collected and concentrated by vacuum distillation to a phenol concentration of 40-80 g / L.

3. The method of claim 1, wherein the preparation of the semi-coke wastewater-based phenolic resin porous carbon adsorbent material is characterized by: In step 2, the sodium hydroxide alkaline hydrolysis modification is carried out by using an 8%-12% sodium hydroxide aqueous solution at 60-80℃ for 2-3 h, and the liquid-solid ratio of the sodium hydroxide aqueous solution to the potato residue is 5-15 mL:1 g.

4. The method of claim 1, wherein the preparation of the semi-coke wastewater-based phenolic resin porous carbon adsorbent material is characterized by: In step 2, the hydrogen peroxide oxidation modification is carried out by using a 5%-8% hydrogen peroxide aqueous solution at 40-50℃ under ultrasonic irradiation at a power of 300-400 W for 1-2 h, and the pH value is adjusted to 3-4 by using a 5%-10% hydrochloric acid aqueous solution before the reaction; the liquid-solid ratio of the hydrogen peroxide aqueous solution to the potato residue is 5-12 mL:1 g.

5. The method of claim 1, wherein the preparation of the semi-coke wastewater-based phenolic resin porous carbon adsorbent material is characterized by: In step 2, the silane coupling agent modification is carried out by using a 3%-5% silane coupling agent ethanol solution at 70-80℃ for 1-1.5 h; the silane coupling agent is KH-550 or KH-560, and the liquid-solid ratio of the silane coupling agent ethanol solution to the potato residue is 4-10 mL:1 g.

6. The method of claim 1, wherein the preparation of the semi-coke wastewater-based phenolic resin porous carbon adsorbent material is characterized by: In step 3, the phenol-rich solution is polymerized with furfural at 90-105℃ for 30-45 min, and the mass ratio of furfural to phenol is 1-2:1; the pH value is adjusted to 8-9 by using a 10%-20% sodium hydroxide aqueous solution before the reaction.

7. The method of claim 1, wherein the preparation of the semi-coke wastewater-based phenolic resin porous carbon adsorbent material is characterized by: In step 3, the amount of the hierarchically modified potato residue is 20%-40% of the mass of the phenol, the amount of urotropine is 10%-15% of the mass of the phenol, the vacuum drying temperature is 60-70℃, and the drying time is 12-16 h.

8. The method of claim 1, wherein the preparation of the semi-coke wastewater-based phenolic resin porous carbon adsorbent material is characterized by: In step 4, the composite resin powder is heated to 300-400℃ at a rate of 5-8℃ / min under nitrogen protection for 1-1.5h, then ZnCl2-citric acid composite activator is added and mixed uniformly, heated to 600-700℃ at a rate of 3-5℃ / min for 2-2.5h, then heated to 800-880℃ at a rate of 2-3℃ / min for 1-1.5h, then cooled to room temperature at a rate of 2-4℃ / min, washed with 5%-10% hydrochloric acid aqueous solution and then deionized water until neutral, dried at 105℃ for 5h to obtain the lan carbon waste water-based phenolic resin porous carbon adsorption material.

9. The method of claim 8, wherein the preparation of the semi-coke wastewater-based phenolic resin porous carbon adsorbent material is characterized by: In step 4, the mass ratio of ZnCl2 to citric acid in the ZnCl2-citric acid composite activator is 3:1, and the amount of the composite activator is 80%-120% of the mass of the composite resin powder; the acid pickling is performed with 5%-10% hydrochloric acid aqueous solution until no bubbles are generated, and then deionized water is used for washing until neutral.

10. A blue water-based phenolic resin porous carbon adsorbent material, characterized in that: The preparation method is prepared by any one of claims 1-9.

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