A nitrogen-doped high-efficiency adsorbent based on discarded traditional Chinese medicine residues and pharmaceutical sludge and its preparation process

Abstract

The present invention belongs to the field of environmental engineering and solid waste resource utilization technology, and is specifically a nitrogen-doped high-efficiency adsorbent based on discarded Chinese medicine residues and pharmaceutical sludge and a preparation process. Specifically, it includes: S1, mixing the discarded Chinese medicine residues and pharmaceutical sludge evenly to obtain a mixed material; the water content of the discarded Chinese medicine residues and the pharmaceutical sludge is 75% to 85%, the mass ratio of the residues to the sludge is 1:1 to 3:1, and the C / N ratio of the mixed material is 25:1. S2, aerobic composting pretreatment of the mixed material to obtain a mixture; S3, adjusting the water content of the mixture and forming a slurry; S4, adding a hydrothermal additive to the slurry to obtain a mixed slurry; S5, subjecting the mixed slurry to a hydrothermal carbonization reaction, and separating the products after the reaction to obtain hydrothermal charcoal and an aqueous phase product; S6, placing the hydrothermal charcoal in an impregnation solution for impregnation, stirring is maintained during the impregnation process, and filtering after the impregnation to obtain a solid phase product; S7, the solid phase product after impregnation is placed in an oven for roasting, and the solid phase obtained after roasting is a nitrogen-doped high-efficiency adsorbent.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental engineering and solid waste resource utilization, and specifically relates to a nitrogen-doped high-efficiency adsorbent, a preparation process and an application thereof. Background Art

[0002] At present, my country has significant industrial advantages in the field of API production and processing, and has become a major user and exporter of APIs in the world in recent years. Solid waste in the pharmaceutical industry has the characteristics of large output, many types, and complex composition. Abandoned Chinese medicine residues and pharmaceutical sludge are currently the two main types of pharmaceutical solid wastes, and they urgently need appropriate disposal paths. In addition, abandoned Chinese medicine residues are rich in lignin components, and pharmaceutical sludge contains various organic matter and nitrogen elements, which makes these two types of wastes have certain resource utilization potential.

[0003] Hydrothermal carbonization is a new type of thermochemical treatment method that can produce hydrothermal carbon materials under high temperature conditions, and then prepare high-value functional materials, providing a broad space for the resource utilization of wet biomass. This patent is based on hydrothermal carbonization technology, combined with the characteristics of discarded Chinese medicine residues and pharmaceutical sludge, through mixed composting pretreatment, impregnation roasting post-treatment and other links, to obtain a high-efficiency adsorbent with excellent adsorption capacity.

[0004] In this process, each link is a low-energy process, and the required reagents are mainly NaOH, KOH and dicyandiamide. The reagents are relatively simple and cheap, and can achieve the disposal of Chinese medicine residues and pharmaceutical sludge and the preparation of high-efficiency adsorbents at a low cost. Existing technologies, "A composite material for water pollution control" (publication number: CN202410408972.8), "A preparation method and application of biochar modified by Chinese medicine residues" (publication number: CN118341391A), "A preparation and application of a phosphorus-modified nano zero-valent iron biochar composite material" (publication number: CN118267971A) also use Chinese medicine residues as raw materials to prepare functional materials that can be used for adsorption, but the processes involved in their processes all require higher reaction temperatures (800°C and above) or more expensive reagents.

[0005] In this process, the lignin component of the Chinese medicine residue is pre-treated by mixing the discarded Chinese medicine residue with the pharmaceutical sludge for composting, which effectively improves the subsequent hydrothermal reactivity of the material, and is conducive to the improvement of the hydrothermal carbon yield and the performance of the adsorbent. In addition, the discarded Chinese medicine residue and the pharmaceutical sludge are solid wastes from the same industry, and the two are produced in the same place. Selecting them as the objects of coordinated disposal can effectively reduce transportation costs. The prior art, "A Nitrogen-Doped Carbon Material and Its Preparation Method and Application" (Publication No.: CN118059837A), uses acid hydrolysis to pre-treat the Chinese medicine residue. This method not only involves the addition of additional acid solution, but also requires heating to 120-150°C; in addition, the above-mentioned prior art uses municipal sludge as the material, which requires additional transportation costs. Therefore, the operating cost of this process is significantly lower than that of the existing process.

[0006] In this process, hydrothermal carbon nitrogen doping is achieved through the impregnation step to further improve the performance of the product adsorbent. The prior art, "A Sludge-Based Hexavalent Chromium Composite Adsorbent and Its Preparation Method" (Publication No.: CN115318241B), adds TEOS and APTES in the process for amino modification reaction, so that the adsorbent is doped with nitrogen and the adsorbent performance is improved; however, the addition of the above-mentioned additional reagents will increase the process cost, while in this process, the use of a nitrogen-rich aqueous phase product as an impregnation liquid can effectively reduce the cost of additional reagents. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention proposes a nitrogen-doped high-efficiency adsorbent based on discarded traditional Chinese medicine residues and pharmaceutical sludge and a preparation process.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A process for preparing a nitrogen-doped high-efficiency adsorbent based on discarded traditional Chinese medicine residues and pharmaceutical sludge, the process flow specifically comprising the following steps:

[0010] Step 1, mixing the discarded Chinese medicine residue and the pharmaceutical sludge uniformly to obtain a mixed material; the moisture content of the discarded Chinese medicine residue and the pharmaceutical sludge is 75% to 85%, the mass ratio of the discarded Chinese medicine residue to the pharmaceutical sludge is (1 to 3): 1, and the C / N ratio of the mixed material is 25: 1;

[0011] Step 2, performing aerobic composting pretreatment on the mixed material to obtain a mixture;

[0012] Step 3, adjusting the moisture content of the mixture to form a slurry;

[0013] Step 4, adding a hydrothermal additive to the slurry and mixing evenly to obtain a mixed slurry, wherein the hydrothermal additive is any one of KOH and NaOH;

[0014] Step 5, subjecting the mixed slurry to a hydrothermal carbonization reaction, and separating the products after the reaction is completed to obtain hydrothermal carbon and an aqueous phase product;

[0015] Step 6, placing the hydrothermal carbon in the impregnation solution for impregnation, maintaining stirring during the impregnation process, and obtaining a solid phase product by filtering after the impregnation is completed, the impregnation solution is prepared by adding dicyandiamide to the hydrothermal carbonization aqueous phase product, and the mass ratio of dicyandiamide to the aqueous phase product is 1:10;

[0016] Step 7: calcining the impregnated solid phase product, and the solid phase obtained after calcination is a nitrogen-doped high-efficiency adsorbent.

[0017] Furthermore, in step 2, the composting time is 48 hours, and the compost is turned once during the composting period.

[0018] Furthermore, in step S3, the water content of the mixture is 90%, and a flowing slurry is formed by stirring; the supplementary water includes distilled water and a hydrothermal carbonization aqueous phase product; when the aqueous phase product is insufficient, distilled water is added to finally adjust the water content of the slurry to the required water content.

[0019] Furthermore, the separated aqueous product is diverted to step 3 as supplementary water for adjusting the water content of the mixture or diverted to step 6 as raw material for preparing the impregnation solution; when the nitrogen content of the aqueous product is less than 3000 mg / L, it is diverted to step 3; when the nitrogen content of the aqueous product is ≥3000 mg / L, it is diverted to step 6.

[0020] Furthermore, the hydrothermal additive is added in solid form, and the amount added is 5% of the slurry mass.

[0021] Furthermore, in step 5, hydrothermal carbonization is carried out in a sequencing batch reactor, the reaction temperature is 180° C., the reaction time is 2 hours, and the reaction pressure is the autogenous pressure generated by the slurry as the reaction temperature increases; after the reaction is completed, solid-liquid phase separation is achieved by vacuum filtration.

[0022] Furthermore, in step 6, the impregnation time is 4 to 6 hours, the temperature is 20 to 30° C., and the mass ratio of the hydrothermal charcoal to the impregnation liquid is 1:4.

[0023] Furthermore, the calcination temperature of the calcination process in step 7 is 150° C., and the calcination time is 2 hours.

[0024] A nitrogen-doped high-efficiency adsorbent based on discarded traditional Chinese medicine residues and pharmaceutical sludge is prepared by the above-mentioned nitrogen-doped high-efficiency adsorbent preparation process based on discarded traditional Chinese medicine residues and pharmaceutical sludge.

[0025] As described above, a nitrogen-doped high-efficiency adsorbent based on discarded traditional Chinese medicine residues and pharmaceutical sludge is used in water environment remediation and sewage treatment.

[0026] Beneficial effects of the present invention:

[0027] 1. The raw materials used in the present invention are discarded Chinese medicine residues and pharmaceutical sludge, which effectively realizes the coordinated disposal and resource utilization of two main solid wastes in the pharmaceutical industry.

[0028] 2. The process of the present invention makes full use of the composition characteristics of discarded traditional Chinese medicine residues and pharmaceutical sludge, increases the number of functional groups on the surface of hydrothermal carbon through the lignin component of the traditional Chinese medicine residue, and uses the nitrogen element in the pharmaceutical sludge to achieve nitrogen doping of hydrothermal carbon, thereby obtaining a highly efficient adsorbent without the need for additional expensive agents.

[0029] 3. The process of the present invention is simple, the process is mild, the additives are few and cheap, and the raw materials are low-value waste and are produced at the same location. Therefore, the process has a significant low-cost feature. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 It is a preparation flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] (1) Preparation of high-efficiency adsorbent: Abandoned Chinese medicine residue and pharmaceutical sludge are mixed and composted at a wet basis weight ratio of 2:1. After 48 hours of composting, the moisture content is adjusted to 90% with distilled water, and 5% of the slurry mass of NaOH is added. Subsequently, hydrothermal carbonization is performed at 180°C for 2 hours to obtain hydrothermal carbon. The hydrothermal carbon is impregnated for 4 hours, and the impregnation liquid is prepared by preparing distilled water and dicyandiamide. Subsequently, it is roasted at 150°C for 2 hours to obtain a high-efficiency adsorbent.

[0035] (2) Test of adsorption performance of high-efficiency adsorbent: Weigh 0.025g of high-efficiency adsorbent into a 250mL stoppered conical flask containing 100mL of tetracycline solution with an initial concentration of 50mg / L, place the conical flask in a constant temperature oscillator, and oscillate in a closed state at 25°C and 180r / min until adsorption equilibrium is reached. After the adsorption is completed, the mixed solution is filtered through a 0.45μm water filter membrane. The residual concentration of tetracycline is determined by a UV-visible spectrophotometer. The equilibrium adsorption amount q is calculated using the following formula: e .

[0036]

[0037] In the formula, C0 and C e represent the initial concentration and equilibrium concentration (mg·L -1 );V represents the volume of solution (L); m represents the dosage of high-efficiency adsorbent (g). The results are shown in Table 1.

[0038] Table 1 Example 1 Tetracycline adsorption results

[0039]

[0040] Example 2

[0041] (1) Preparation of high-efficiency adsorbent: Abandoned Chinese medicine residue and pharmaceutical sludge are mixed and composted at a wet basis weight ratio of 1:1. After 48 hours of composting, the moisture content is adjusted to 90% with distilled water, and 5% of the slurry mass of NaOH is added. Subsequently, hydrothermal carbonization is performed at 180°C for 2 hours to obtain hydrothermal carbon. The hydrothermal carbon is impregnated for 4 hours, and the impregnation liquid is prepared by preparing distilled water and dicyandiamide. Subsequently, it is roasted at 150°C for 2 hours to obtain a high-efficiency adsorbent.

[0042] (2) Test of adsorption performance of high-efficiency adsorbent: Same as Example 1.

[0043] Table 2 Example 2 Tetracycline adsorption results

[0044]

[0045] Example 3

[0046] (1) Preparation of high-efficiency adsorbent: Waste Chinese medicine residue and pharmaceutical sludge are mixed and composted at a wet basis weight ratio of 1:1. After 48 hours of composting, the moisture content is adjusted to 90% with distilled water, and 5% of the slurry mass of NaOH is added. Subsequently, hydrothermal carbonization is performed at 180°C for 2 hours to obtain hydrothermal charcoal. The hydrothermal charcoal is impregnated for 4 hours, and the impregnation liquid is prepared by configuring the liquid product (nitrogen content 2754 mg / L), distilled water and dicyandiamide. Subsequently, it is roasted at 150°C for 2 hours to obtain a high-efficiency adsorbent.

[0047] (2) Test of adsorption performance of high-efficiency adsorbent: Same as Example 1.

[0048] Table 3 Example 3 Tetracycline adsorption results

[0049]

[0050] Example 4

[0051] (1) Preparation of high-efficiency adsorbent: same as in Example 1

[0052] (2) Test of adsorption performance of high-efficiency adsorbent: Weigh 0.025g of high-efficiency adsorbent into a 250mL stoppered conical flask containing 100mL of methylene blue solution with an initial concentration of 50mg / L, place the conical flask in a constant temperature oscillator, and oscillate in a closed state at 25°C and 180r / min until adsorption equilibrium is reached. After the adsorption is completed, the mixed solution is filtered through a 0.45μm water filter membrane. The residual concentration of methylene blue is determined by a UV-visible spectrophotometer. The equilibrium adsorption amount q is calculated using the following formula: e .

[0053]

[0054] In the formula, C0 and C e represent the initial concentration and equilibrium concentration (mg·L -1 ); V represents the volume of solution (L); m represents the dosage of high-efficiency adsorbent (g). The results are shown in Table 4.

[0055] Table 4 Example 4 Methylene blue adsorption results

[0056]

[0057] Example 5

[0058] (1) Preparation of high-efficiency adsorbent: same as in Example 2

[0059] (2) Test of adsorption performance of high-efficiency adsorbent: Same as Example 4

[0060] Table 5 Example 5 Methylene blue adsorption results

[0061]

[0062] Comparative Example 1

[0063] In Comparative Example 1, the waste Chinese medicine residue and pharmaceutical sludge were mixed and composted at a wet basis weight ratio of 0.5:1, and then a tetracycline adsorption experiment was carried out, and other conditions were the same as in Example 1. The results are shown in Table 6.

[0064] Table 6 Comparative Example 1 Tetracycline adsorption results

[0065]

[0066] In this comparative example 1, due to the low blending ratio of the waste Chinese medicine residue, the C / N ratio in the compost pretreatment process is poor and the lignin decomposition is weak. In addition, the low blending ratio of the waste Chinese medicine residue leads to a reduction in the number of oxygen-containing functional groups on the surface of the subsequent adsorbent, so that the adsorption effect of this comparative example 1 is much lower than that of Example 1.

[0067] Comparative Example 2

[0068] In Comparative Example 2, the waste Chinese medicine residue and pharmaceutical sludge were mixed and composted at a wet basis weight ratio of 5:1, and then a tetracycline adsorption experiment was carried out, and other conditions were the same as in Example 1. The results are shown in Table 7.

[0069] Table 7 Comparative Example 2 Tetracycline adsorption results

[0070]

[0071] In this comparative example 2, due to the excessively high proportion of waste Chinese medicinal residues mixed, the C / N ratio of the compost pretreatment process is not good, and the lignin decomposition is weak. As a result, a large amount of undecomposed lignin components block the adsorbent pores in the subsequent hydrothermal carbonization, and effective adsorption sites cannot be formed. As a result, the adsorption effect of this comparative example 2 is much lower than that of Example 1.

[0072] Comparative Example 3

[0073] In Comparative Example 3, the discarded Chinese medicine residues were directly blended and composted, and then a tetracycline adsorption experiment was carried out, and other conditions were the same as those in Example 1. The results are shown in Table 8.

[0074] Table 8 Comparative Example 3 Tetracycline adsorption results

[0075]

[0076] In this comparative example 3, since discarded Chinese medicine residues are directly used to prepare the adsorbent, there is a lack of functional group linking matrix under hydrothermal conditions, the charring effect is poor and the linked oxygen-containing functional groups are very few, resulting in the adsorption effect of this comparative example 3 being much lower than that of Example 1.

[0077] Comparative Example 4

[0078] In Comparative Example 4, the pharmaceutical sludge was directly blended and composted, and then a tetracycline adsorption experiment was carried out, and other conditions were the same as those in Example 1. The results are shown in Table 9.

[0079] Table 9 Comparative Example 4 Tetracycline adsorption results

[0080]

[0081] In this comparative example 3, since pharmaceutical waste is directly used to prepare the adsorbent, there is a lack of functional group donors under hydrothermal conditions, resulting in very few oxygen-containing functional groups on the adsorbent surface. Therefore, the adsorption effect of this comparative example 4 is much lower than that of Example 1.

[0082] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0083] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A process for preparing a nitrogen-doped high-efficiency adsorbent based on discarded Chinese medicine residues and pharmaceutical sludge, characterized in that: The process specifically comprises the following steps: Step 1, mixing the discarded Chinese medicine residue and the pharmaceutical sludge uniformly to obtain a mixed material; the moisture content of the discarded Chinese medicine residue and the pharmaceutical sludge is 75% to 85%, the mass ratio of the discarded Chinese medicine residue to the pharmaceutical sludge is (1 to 3): 1, and the C / N ratio of the mixed material is 25: 1; Step 2, performing aerobic composting pretreatment on the mixed material to obtain a mixture; Step 3, adjusting the moisture content of the mixture to form a slurry; Step 4, adding a hydrothermal additive to the slurry and mixing evenly to obtain a mixed slurry, wherein the hydrothermal additive is any one of KOH and NaOH; Step 5, subjecting the mixed slurry to a hydrothermal carbonization reaction, and separating the products after the reaction is completed to obtain hydrothermal carbon and an aqueous phase product; Step 6, placing the hydrothermal carbon in the impregnation solution for impregnation, maintaining stirring during the impregnation process, and obtaining a solid phase product by filtering after the impregnation is completed, the impregnation solution is prepared by adding dicyandiamide to the hydrothermal carbonization aqueous phase product, and the mass ratio of dicyandiamide to the aqueous phase product is 1:10; Step 7: calcining the impregnated solid phase product, and the solid phase obtained after calcination is a nitrogen-doped high-efficiency adsorbent.

2. The process for preparing a nitrogen-doped high-efficiency adsorbent based on discarded Chinese medicine residues and pharmaceutical sludge according to claim 1, characterized in that: The composting time in step 2 is 48 hours, and the compost is turned once during the composting period.

3. The process for preparing a nitrogen-doped high-efficiency adsorbent based on discarded Chinese medicine residues and pharmaceutical sludge according to claim 1, characterized in that: The water content of the mixture in step 3 is 90%, and a flowing slurry is formed by stirring; the supplementary water includes distilled water and hydrothermal carbonization water phase product; when the water phase product is insufficient, distilled water is added to finally adjust the water content of the slurry to the required water content.

4. The process for preparing a nitrogen-doped high-efficiency adsorbent based on discarded Chinese medicine residues and pharmaceutical sludge according to claim 1, characterized in that: The separated aqueous product is diverted to step 3 as supplementary water for adjusting the water content of the mixture or diverted to step 6 as raw material for preparing the impregnation solution; when the nitrogen content of the aqueous product is less than 3000 mg / L, it is diverted to step 3; when the nitrogen content of the aqueous product is ≥3000 mg / L, it is diverted to step 6.

5. The process for preparing a nitrogen-doped high-efficiency adsorbent based on discarded Chinese medicine residues and pharmaceutical sludge according to claim 1, characterized in that: The hydrothermal additive is added in solid form, and the amount added is 5% of the slurry mass.

6. The process for preparing a nitrogen-doped high-efficiency adsorbent based on discarded Chinese medicine residues and pharmaceutical sludge according to claim 1, characterized in that: In the step 5, the hydrothermal carbonization is carried out in a sequencing batch reactor, the reaction temperature is 180° C., the reaction time is 2 hours, and the reaction pressure is the autogenous pressure generated by the slurry as the reaction temperature increases; after the reaction is completed, solid-liquid phase separation is achieved by vacuum filtration.

7. The process for preparing a nitrogen-doped high-efficiency adsorbent based on discarded Chinese medicine residues and pharmaceutical sludge according to claim 1, characterized in that: In step 6, the impregnation time is 4 to 6 hours, the temperature is 20 to 30° C., and the mass ratio of the hydrothermal charcoal to the impregnation liquid is 1:

4.

8. The process for preparing a nitrogen-doped high-efficiency adsorbent based on discarded Chinese medicine residues and pharmaceutical sludge according to claim 1, characterized in that: In the step 7, the calcination temperature of the calcination process is 150° C. and the calcination time is 2 hours.

9. A nitrogen-doped high-efficiency adsorbent based on discarded Chinese medicinal residues and pharmaceutical sludge, prepared by the preparation process of a nitrogen-doped high-efficiency adsorbent based on discarded Chinese medicinal residues and pharmaceutical sludge according to any one of claims 1 to 8.

10. The nitrogen-doped high-efficiency adsorbent based on discarded Chinese medicine residues and pharmaceutical sludge as described in claim 9 is used for water environment restoration and sewage treatment.

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