Biomass carbon adsorbent, preparation method and application of biomass carbon adsorbent in wastewater treatment
By preparing thin-layer porous carbon adsorbents, the problem of removing organic complexed nickel from strongly alkaline electroplating wastewater was solved, achieving efficient and economical large-scale treatment and demonstrating excellent adsorption performance and renewability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-27
- Publication Date
- 2026-05-01
AI Technical Summary
Existing adsorbents are difficult to effectively remove stable organic complex nickel in the treatment of strongly alkaline electroplating wastewater, and traditional preparation methods are complex and costly, making it difficult to achieve large-scale application.
Thin-layer porous carbon adsorbent (TLPC) was prepared using biomass materials. Through chemical exfoliation and microwave modification, a multi-layer structure was formed, introducing micropores and surface functional groups. Combined with microwave-assisted redox reactions, the adsorption performance was improved.
It efficiently removes organic complexed nickel over a wide pH range (pH 5–11), significantly improving adsorption capacity and regenerability while reducing operating costs. It is suitable for the efficient treatment of strongly alkaline electroplating wastewater.
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Figure CN121944994A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of wastewater treatment technology, and particularly relates to a biomass carbon adsorbent, its preparation method, and its application in electroplating wastewater treatment. Background Technology
[0002] Nickel (Ni) is widely used in various industries, including electroplating, battery manufacturing, textiles, and electronics. With the discharge of industrial wastewater, the concentration of nickel in the environment is constantly increasing, posing a serious risk to human health. To protect public health, the U.S. Environmental Protection Agency (USEPA) and the World Health Organization (WHO) have set limits for nickel emissions into industrial wastewater (0.1 mg / L) and drinking water (0.01 mg / L), respectively. Effective removal of nickel from the aquatic environment has become a crucial research focus.
[0003] Currently, various treatment technologies have been reported, mainly including chemical precipitation (such as generating hydroxides or sulfides), advanced oxidation processes (such as electrochemical oxidation, electrocoagulation or Fenton process), and adsorption methods.
[0004] Among these methods, adsorption, which utilizes adsorbents such as activated alumina, zeolite, metal oxides, and clay minerals, is considered one of the simplest and most economical. However, these traditional adsorbents are expensive and mostly non-renewable materials, limiting their large-scale application.
[0005] Biomass carbon has become an attractive alternative adsorbent due to its low cost, abundant sources, and good adsorption properties. However, under neutral conditions, ordinary biomass carbon... equilibrium adsorption capacity ( The specific surface area is typically only 2–10 mg / g, indicating that adsorption performance needs further improvement. Modulating the surface functional groups and transforming the dense structure into a layered or stratified structure can increase the specific surface area and introduce more reaction sites, which is an effective way to improve adsorption performance. Exfoliation is widely considered one of the simplest and most economical strategies for the large-scale preparation of functional carbon materials. It mainly obtains highly crystalline cellulose materials by selectively hydrolyzing lignin and hemicellulose. Various exfoliation techniques have been reported, including mechanical, thermal, and electrochemical treatments. However, these methods often result in poorly arranged layered structures in the obtained carbon materials, making them prone to self-stacking and severely reducing their adsorption capacity.
[0006] To further enhance the adsorption performance of biochar for heavy metals such as nickel, modification with metals or metal oxides is considered a promising strategy. Precisely introducing metals into the carbon framework can improve atom utilization and ensure a uniform distribution of active sites. However, traditional metal coating methods are typically complex, costly, and difficult to implement on a large scale. Therefore, developing a simple method for large-scale production of high-performance biochar materials using biomass is crucial for advancing adsorption processes to remove nickel pollution from water.
[0007] Furthermore, previous studies on nickel adsorption have mostly been conducted in simple aqueous systems with a pH of 4–7, within which nickel exists primarily in the Ni²⁺ ionic form and is relatively easy to remove through adsorption or precipitation by pH adjustment. However, the real challenge in nickel removal lies in handling strongly alkaline environments containing strong organic ligands—such as typical electroplating wastewater (pH approximately 11), where nickel forms highly stable organic complexes (e.g., complexing with triethanolamine (TEOA), tetraethylenepentamine (TEPA), etc.). These complexes possess high stability and a high negative charge, making their removal extremely difficult using conventional adsorption techniques.
[0008] Therefore, there is an urgent need in this field to develop a new type of adsorbent that can obtain a stable thin-layer porous structure and high specific surface area through a simple and economical preparation method, is effective in a wide pH range (especially under strongly alkaline conditions), and has high adsorption capacity and efficient removal capability for different forms of nickel (especially stable organic complex nickel). Summary of the Invention
[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a biomass carbon adsorbent, its preparation method, and its application in wastewater treatment.
[0010] A method for preparing a thin-layered porous biomass carbon adsorbent (TLPC) includes the following steps:
[0011] Step 1: Collect biomass materials and clean and dry them (naturally dry in the sun, blow dry by wind, or dry at low temperature).
[0012] Step 2: Grind the cleaned and dried biomass material into powder with a particle size of 0.1–0.6 mm;
[0013] Step 3: Mix the ground biomass powder with a nitric acid solution with a concentration of 1.1–2.1 M to form a mixed suspension of biomass powder and nitric acid;
[0014] Step 4: Chemically strip the biomass powder: The mixture of biomass powder and nitric acid is reacted at a temperature of 70-120°C and a pressure of 31-199 kPa for a set time.
[0015] Step 5: Filter the reaction product from step 4 and dry the filtered solid powder.
[0016] Step 6: Place the dried solid powder in a nitrogen atmosphere, heat it to the target temperature at a set heating rate, and calcine it at the target temperature for a set time to obtain the calcined powder.
[0017] Step 7: Wash the calcined powder with deionized water until neutral, then dry it at 45-60 ℃ and store it in a sealed container.
[0018] As a preferred option:
[0019] The biomass materials collected in step 1 include bamboo, eggshells, coconut shells, straw, peanut shells, rice husks, and wood;
[0020] The bamboo collected was 2 to 7 years old.
[0021] Preferably, steps 1 to 7 are as follows:
[0022] Step 1: Collect bamboo that is 3 to 4 years old and growing in Yixing, Jiangsu, China, and clean and dry the bamboo (naturally dry it in the sun).
[0023] Step 2: Use a grinder to grind the cleaned and dried bamboo into powder with a particle size of 0.2 to 0.4 mm;
[0024] Step 3: Mix the ground bamboo powder with a 1.1-1.6 M nitric acid solution at a ratio of 2.5 L of nitric acid solution to 1 kg of bamboo powder to form a mixed suspension of bamboo powder and nitric acid.
[0025] Step 4: Chemically exfoliate the bamboo powder: In a high-pressure reactor, react the bamboo powder and nitric acid suspension at a temperature of 70-120 °C and a pressure of 100-170 kPa for 2 h.
[0026] Step 5: Filter the reaction product from step 4, and dry the filtered solid powder at 100 °C for 24 h using an oven.
[0027] Step 6: Place the dried solid powder under a nitrogen atmosphere and heat it to 550°C at a heating rate of 5°C / min, and calcine it at the target temperature for 2 hours to obtain the calcined powder.
[0028] Step 7: Wash the calcined powder with deionized water until neutral, then dry it at 45-60 ℃ and store it in a sealed container.
[0029] A thin-layer porous biomass carbon adsorbent prepared using this method:
[0030] Thin-layer porous biomass carbon adsorbents have a multi-layered structure with interconnected topologies. Each layer contains micropores and mesopores with a pore size of 1.5–2.0 nm and a pore volume of 0.18–0.3 cm³. 3 g -1 ;
[0031] The thin-layer porous biomass carbon adsorbent comprises 1.5–6.5 wt% N, 45–66 wt% C and 20–50 wt% O by mass percentage;
[0032] The specific surface area of thin-layer porous biomass carbon adsorbent is 400–600 m². 2 / g.
[0033] Application method of this thin-layer porous biomass carbon adsorbent: The thin-layer porous biomass carbon adsorbent is applied as a nickel adsorbent in organic complex nickel wastewater with a pH value of 11 and a nickel concentration of less than 100 mg / L. TLPC is relatively easy to regenerate and can be acid-washed to desorb the nickel.
[0034] A sort of Modified thin-layer porous biomass carbon adsorbent ( The preparation method of -TLPC (Manganese dioxide-decorated thin layered porous carbon) includes the following steps:
[0035] Step 1: Collect biomass materials and clean and dry them (naturally dry in the sun, blow dry by wind, or dry at low temperature).
[0036] Step 2: Grind the cleaned and dried biomass material into powder with a particle size of 0.1–0.6 mm;
[0037] Step 3: Mix the ground biomass powder with a nitric acid solution with a concentration of 1.1–2.1 M to form a mixed suspension of biomass powder and nitric acid;
[0038] Step 4: Chemically strip the biomass powder: The mixture of biomass powder and nitric acid is reacted at a temperature of 70-120°C and a pressure of 31-199 kPa for a set time.
[0039] Step 5: Filter the reaction product from step 4 and dry the filtered solid powder.
[0040] Step 6: Place the dried solid powder in a nitrogen atmosphere, heat it to the target temperature at a set heating rate, and calcine it at the target temperature for a set time to obtain the calcined powder.
[0041] Step 7: Wash the calcined powder with deionized water until neutral, and then dry it at 45-60 °C to obtain a thin-layer porous biomass carbon adsorbent.
[0042] Step 8: Use a microwave-assisted method to process the thin-layer porous biomass carbon adsorbent. Modification: Weigh out the following according to the ratio of (0.1~2):1. The thin-layer porous biomass carbon adsorbent obtained in step 7 will be weighed out. The thin-layer porous biomass carbon adsorbent was mixed with deionized water at a ratio of 1 g to 10 ml. The resulting mixture was heated in a microwave at 600–1200 W for 20–60 s, stirred until homogeneous, and then microwaved for another 1.5–5 min to obtain the expanded product. Microwave heating accelerated the redox reaction, rapidly decomposed the precursor, promoted efficient anchoring and growth of metals on carbon in the thin-layer porous biomass carbon adsorbent (TLPC), and improved dispersibility and stability.
[0043] Step 9: Dry the puffed product at 60–80 °C for 10–24 h to obtain... Modified thin-layer porous biomass carbon adsorbent ( -TLPC), seal and store for later use.
[0044] As a preferred option:
[0045] The biomass materials collected in step 1 include bamboo, eggshells, coconut shells, straw, peanut shells, rice husks, and wood;
[0046] The bamboo collected was 2 to 7 years old.
[0047] As a preferred option, steps 1 to 9 are specifically as follows:
[0048] Step 1: Collect bamboo that is 3 to 4 years old and growing in Yixing, Jiangsu, China, and clean and dry the bamboo (naturally dry it in the sun).
[0049] Step 2: Use a grinder to grind the cleaned and dried bamboo into powder with a particle size of 0.2 to 0.4 mm;
[0050] Step 3: Mix the ground bamboo powder with a 1.1-1.6 M nitric acid solution at a ratio of 2.5 L of nitric acid solution to 1 kg of bamboo powder to form a mixed suspension of bamboo powder and nitric acid.
[0051] Step 4: Chemically exfoliate the bamboo powder: In a high-pressure reactor, react the bamboo powder and nitric acid suspension at a temperature of 70-120 °C and a pressure of 100-170 kPa for 2 h.
[0052] Step 5: Filter the reaction product from step 4, and dry the filtered solid powder at 100 °C for 24 h using an oven.
[0053] Step 6: Place the dried solid powder under a nitrogen atmosphere and heat it to 550°C at a heating rate of 5°C / min, and calcine it at the target temperature for 2 hours to obtain the calcined powder.
[0054] Step 7: Wash the calcined powder with deionized water until neutral, then dry it at 45-60 ℃ and store it in a sealed container;
[0055] Step 8: Use a microwave-assisted method to process the thin-layer porous biomass carbon adsorbent. Modification: Weigh 1g of each according to the ratio of (0.1~2):1. And 1g of the thin-layer porous biomass carbon adsorbent obtained in step 7, weigh out... The mixture was mixed with a thin-layer porous biomass carbon adsorbent in 10 ml of deionized water; the resulting mixture was heated in a microwave oven at 800 W for 30 s, stirred evenly, and then microwaved for another 2 min to obtain the puffed product.
[0056] Step 9: Dry the puffed product at 80 °C for 12 h to obtain... Modified thin-layer porous biomass carbon adsorbent ( -TLPC), seal and store for later use.
[0057] A preparation using this method Modified thin-layer porous biomass carbon adsorbent:
[0058] The modified thin-layer porous biomass carbon adsorbent has a multi-layered structure at its microscopic level, with micron-sized particles deposited on the layered structure. The particles (i.e., parts of the carbon atoms in each layer are modified with micron-sized particles) The layers are topologically interconnected, and each layer contains micropores; the micropores have a pore size of 1.5–2.0 nm and a pore volume of 0.18–0.3 cm³. 3 g -1 ;
[0059] By weight percentage, The modified thin-layer porous biomass carbon adsorbent comprises 1.3–6.2 wt% N, 43–62 wt% C, 21–52 wt% O and 0.5–1 wt% Mn;
[0060] The modified thin-layer porous biomass carbon adsorbent has a specific surface area of 400–600 m². 2 / g.
[0061] A kind of Application methods of modified thin-layer porous biomass carbon adsorbents:
[0062] Will Modified thin-layer porous biomass carbon adsorbents were used as nickel adsorbents in inorganic nickel wastewater with a pH value of 5–8.5.
[0063] Or Modified thin-layer porous biomass carbon adsorbents were used as nickel adsorbents in organic complex nickel wastewater with a pH of 5–11.
[0064] The beneficial effects of this invention are:
[0065] This invention successfully prepared a biomass carbon adsorbent (TLPC) with a stable thin-layer porous structure and its... Modified products ( -TLPC).
[0066] This TLPC adsorbent maintains a high removal rate of complexed nickel in electroplating wastewater containing highly stable organic complexing agents in a strongly alkaline environment (pH approximately 11), effectively solving the industry dilemma of traditional adsorbents easily failing under such extreme conditions. Furthermore, TLPC exhibits excellent renewability, significantly reducing operating costs.
[0067] -TLPC exhibits a wider pH range (pH 5–11) and superior adsorption performance, and -TLPC can still maintain stable nickel removal performance in complex organic matrices.
[0068] This invention enables the large-scale preparation of high-performance adsorbents through a simple process, providing a reliable technical solution for the efficient and economical removal of nickel from challenging electroplating wastewater. Attached Figure Description
[0069] Figure 1 middle, Figure 1 a is a schematic diagram of the synthesis path of TLPC in Example 1; Figure 1 b and Figure 1 c are images of TLPC obtained by chemical stripping with nitric acid solution of optimal nitric acid concentration in Example 1, taken under a scanning electron microscope (SEM). Figure 1 d and Figure 1 e are characterization images of TLPC obtained by chemical stripping with nitric acid solution of optimal nitric acid concentration in Example 1, obtained by energy dispersive X-ray spectroscopy (EDX).
[0070] Figure 2 middle, Figure 2 a is in Example 2 A path diagram for modifying TLPC. Figure 2 b to Figure 2 f is - SEM-EDX characterization results of TPLC Figure 2 g is -XRD characterization results of TPLC Figure 2 h is -FTIR characterization results of TPLC Figure 2 i is -XPS characterization results of TPLC;
[0071] Figure 3 middle, Figure 3 a represents the Ni content in the inorganic nickel ion-simulated wastewater (simulated wastewater 1) that contains no organic matter. 2+ In TLPC and - Adsorption effect diagram on TLPC Figure 3 b represents the relationship between TLPC and pH value of 7.0. -TLPC for Ni in simulated wastewater 1 2+ A fitting plot of the adsorption capacity;
[0072] Figure 4 For different load -TLPC analysis of Ni in inorganic nickel ion-simulated wastewater (simulated wastewater 1) containing no organic matter 2+ Adsorption effect diagram;
[0073] Figure 5 For TLPC and -Isoelectric point test results of TLPC;
[0074] Figure 6 For Ni 2+ and - Schematic diagram of inner-layer coordination between oxygen- and nitrogen-containing functional groups in TPLC;
[0075] Figure 7 middle, Figure 7 a is a complex of Ni 2+In TLPC and - Adsorption diagram on TLPC Figure 7 b is the effect of pH 11.0 on TLPC and Ni on TLPC 2+ A fitting plot of adsorption capacity;
[0076] Figure 8 middle: Figure 8 a represents the different dosages of TLPC added to the actual wastewater at a pH of 11.0. -TLPC for Ni 2 + Removal rate graph; Figure 8 b represents the different dosages of TLPC at a pH of 11.0. -Graph showing the TOC removal rate in the actual wastewater where TLPC is located; Figure 8 c is the Ni obtained from durability tests on the adsorbent at different cycle numbers. 2+ The removal rate graph. Detailed Implementation
[0077] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
[0078] Example 1
[0079] A method for preparing a thin-layer porous biomass carbon adsorbent (TLPC), such as... Figure 1 As shown in a, the steps include:
[0080] Step 1: Collect bamboo that is 3 to 4 years old and growing in Yixing, Jiangsu, China, and clean and dry the bamboo (naturally dry it in the sun).
[0081] Step 2: Use a grinder to grind the cleaned and dried bamboo into powder with a particle size of 0.2 to 0.4 mm;
[0082] Step 3: Mix the ground bamboo powder with nitric acid solutions of 5 wt%, 10 wt%, 10-15 wt%, and 20 wt% by mass, at a ratio of 2.5 L of nitric acid solution to 1 kg of bamboo powder (to investigate the effect of acid strength on the surface properties of TLPC), to form a mixed suspension of bamboo powder and nitric acid.
[0083] Step 4: Use nitric acid as a stripping agent to chemically strip bamboo powder: In a high-pressure reactor, react the bamboo powder and nitric acid mixture suspension at 120 °C and 100–170 kPa for 2 h; Nitric acid can regulate the surface morphology (pore structure / thin layer structure) of bamboo, introduce surface functional groups and improve physicochemical properties.
[0084] Step 5: Filter the reaction product from step 4, and dry the filtered solid powder at 100 °C for 24 h using an oven.
[0085] Step 6: Place the dried solid powder under a nitrogen atmosphere and heat it to 550°C at a heating rate of 5°C / min, and calcine it at the target temperature for 2 hours to obtain the calcined powder.
[0086] Step 7: Wash the calcined powder with deionized water until neutral, and then dry it at 45-60 °C to obtain a thin-layer porous biomass carbon adsorbent, which is then sealed and stored.
[0087] The specific surface area, micropore diameter, micropore volume, and N, C, and O content of the thin-layer porous biomass carbon adsorbent (TLPC) obtained by chemical exfoliation with 5 wt%, 10 wt%, 10–15 wt%, and 20 wt% nitric acid solutions are shown in Table 1 below:
[0088] Table 1. Performance parameters of TLPC at different nitric acid concentrations.
[0089] Nitric acid concentration (wt%) <![CDATA[Specific surface area (m 2 / g)]]> Aperture (nm) <![CDATA[Pore volume (cm 3 g -1 )]]> Ni content (wt%) C content (wt%) O content (wt%) 0 25.01 0.35 0.004 0.80 91.42 2.25 5 478.58 1.71 0.20 1.62 48.96 49.33 10～15 537.09 1.94 0.26 6.32 65.66 20.89 20 57.38 1.95 0.02 6.81 70.60 12.39
[0090] It can be seen from Table 1 above:
[0091] TLPC obtained by chemical stripping with 5 wt% nitric acid solution has high oxygen content (O content) and specific surface area, but excessive oxidation occurs.
[0092] The oxidation effect of TLPC obtained by chemical exfoliation with 10-15 wt% nitric acid solution is the best, with a specific surface area of 537.09 m² / g and better structure and pore formation, indicating that the hydrolysis of lignin and hemicellulose is relatively good.
[0093] The TLPC obtained by chemical exfoliation with 20 wt% nitric acid solution exhibited structural collapse and pore aggregation, and its specific surface area was significantly reduced (to 57.38 m² / g), which may be due to excessive chemical exfoliation with nitric acid solution.
[0094] Therefore, a 10–15 wt% nitric acid solution is the most suitable mass fraction range for the chemical stripping of bamboo. This 10–15 wt% nitric acid solution is the most suitable for the chemical stripping of biomass, enabling the preparation of thin-layer porous biomass carbon adsorbents with high specific surface area and pore size. A schematic diagram of the preparation route is shown below. Figure 1 As shown in a.
[0095] Example 2
[0096] A sort of Modified thin-layer porous biomass carbon adsorbent ( The preparation method of TLPC includes the following steps:
[0097] Step 1: Collect bamboo that is 3 to 4 years old and growing in Yixing, Jiangsu, China, and clean and dry the bamboo (naturally dry it in the sun).
[0098] Step 2: Use a grinder to grind the cleaned and dried bamboo into powder with a particle size of 0.2 to 0.4 mm;
[0099] Step 3: Mix the ground bamboo powder with a 1.1-1.6 M nitric acid solution at a ratio of 2.5 L of nitric acid solution to 1 kg of bamboo powder to form a mixed suspension of bamboo powder and nitric acid.
[0100] Step 4: Chemically exfoliate the bamboo powder: In a high-pressure reactor, react the bamboo powder and nitric acid suspension at a temperature of 70-120 °C and a pressure of 100-170 kPa for 2 h.
[0101] Step 5: Filter the reaction product from step 4, and dry the filtered solid powder at 100 °C for 24 h using an oven.
[0102] Step 6: Place the dried solid powder under a nitrogen atmosphere and heat it to 550°C at a heating rate of 5°C / min, and calcine it at the target temperature for 2 hours to obtain the calcined powder.
[0103] Step 7: Wash the calcined powder with deionized water until neutral, then dry it at 45-60 ℃ and store it in a sealed container;
[0104] Step 8: Use a microwave-assisted method to process the thin-layer porous biomass carbon adsorbent. Modification: Weigh 1g of each according to the ratio of (0.1~2):1. And 1g of the thin-layer porous biomass carbon adsorbent obtained in step 7, weigh out... The mixture was mixed with a thin-layer porous biomass carbon adsorbent in 10 ml of deionized water; the resulting mixture was heated in a microwave oven at 800 W for 30 s, stirred evenly, and then microwaved for another 2 min to obtain the puffed product.
[0105] Step 9: Dry the puffed product at 80 °C for 12 h to obtain... Modified thin-layer porous biomass carbon adsorbent ( -TLPC), seal and store for later use.
[0106] I. The TLPC obtained in Example 1 and the TLPC obtained in Example 2 were compared using the following methods. -TLPC performs scanning and analysis:
[0107] (1) The adsorbents (TLPC and) were characterized by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The morphology of -TLPC;
[0108] (2) The adsorbents (TLPC and) were analyzed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Chemical properties of -TLPC;
[0109] (3) The adsorbent (TLPC and) was obtained by using nitrogen adsorption-desorption isotherms and BET model calculations. Specific surface area of TLPC;
[0110] (4) Determination of adsorbents (TLPC and) by potentiometric titration The zero charge point (pHpzc) of TLPC is determined by the positional titration method, which involves titrating 10 g of adsorbent (TLPC or -TLPC) at the zero charge point (pHpzc). Add 100 mL of 0.1 TLPC solution. In the solution, after equilibrium is reached, 5% of the solution was used. Titrate with 5 M NaOH, keeping the pH value within the range of 3 to 12 to avoid solid dissolution under extreme acidic or alkaline conditions.
[0111] like Figure 1 b and Figure 1 As shown in c, SEM analysis reveals that TLPC possesses interlaminar extended interlayer corridors and an integrally interconnected thin-layer porous framework; as Figure 1 d and Figure 1 As shown in e, the SEM-EDS results indicate that C and O are uniformly distributed on the TLPC surface;
[0112] like Figure 2 As shown in figure a, SEM display Successfully deposited on the layered structure of TLPC, and formed micron-sized MnO2 particles on the TPLC microstructure; such as Figure 2 b to Figure 2 As shown in f, - The C, O, and Mn content is uniformly distributed on the surface of TLPC; such as Figure 2 As shown in g, XRD analysis indicates -TLPC diffraction peaks and tetragonal (PDF: 43-1456) Matches well; as Figure 2 As shown in h, FTIR analysis shows -TLPC in The appearance of a new peak in the range proves that Mn deposition was successful, while the weakening of the oxygen functional group peak intensity indicates... It interacts with oxygen functional groups; such as Figure 2 As shown in figure i, XPS analysis further confirms... The deposition of C1s, O1s and N1s spectra all showed changes in peak positions, indicating that the surface functional groups underwent transformation. Figure 2 (a) to Figure 2 The overall results of (i) indicate that Modification alters the surface morphology and oxygen and nitrogen functional groups of TLPC, suggesting that its adsorption mechanism differs from that of TLPC in the following ways: XPS characterization further confirms this. It mainly binds to oxygen-containing functional groups and oxygen-nitrogen functional groups on the TPLC surface, such as C-OH, C=O, -CONH-, etc., thereby increasing the isoelectric point of TPLC. -The isoelectric point of TPLC is 8.5, which is higher than that of TPLC (7.0), and is... After combining with the functional groups, in addition to electrostatic adsorption, Ni in the solution can be further removed through inner-layer coordination of oxygen and nitrogen functional groups. 2+. .
[0113] II. The TLPC obtained in Example 1 and the TLPC obtained in Example 2 are compared using the following methods. -TLPC conducts adsorbent effectiveness testing:
[0114] Batch adsorption experiments were conducted under different pH conditions to determine TLPC or -TLPC's ability to remove Ni²⁺:
[0115] In simulated wastewater 1 (inorganic nickel ion simulated wastewater without organic matter), simulated wastewater 2 (nickel complexed with nickel + triethanolamine + tetraethylenepentamine simulated wastewater), and actual wastewater with initial Ni²⁺ concentrations of 5–500 mg / L, 1 g / L of adsorbent (TLPC or...) was added. -TLPC), and isothermal experiments were conducted at pH 7.0 ± 0.1;
[0116] The actual wastewater was collected from Changzhou, Jiangsu Province, and contained high concentrations of nickel and organometallic complexing agents. High-resolution liquid chromatography-mass spectrometry (HRLC-MS) analysis revealed the presence of triethanolamine (TEOA) and tetraethylenepentamine (TEPA) in the wastewater. Both TEOA and TEPA are strong nickel complexing agents. Based on the composition of the actual wastewater, the designed formulation for synthesizing the wastewater was: 0.7 mM TEPA, 1.6 mM TEOA, and 0.36 mM... 8 mM and 34 mM Under different pH conditions (3, 5, 7, 9, 11), and with the addition of different doses (1, 5, 20, 50 g / L) of TLPC or Under TLPC conditions, for actual wastewater Adsorption experiments to assess removal capacity; all wastewater samples in the adsorption experiments were filtered through a 0.22 μm PVDF membrane and treated with 2 wt% [a specific filtration process]. Dilution was performed; in the adsorption experiment, the results were determined by ICP-MS. Concentration was determined by measuring total organic carbon (TOC) using a TOC analyzer (TOC-L CPH, Shimadzu, Japan).
[0117] (1) Characterization of adsorption effect in simulated wastewater 1 (inorganic nickel ion simulated wastewater without organic matter):
[0118] Simulated wastewater 1 contains ;
[0119] At pH 7.0, TLPC... The removal rate was only 16.5 ± 0.5%, while -TLPC ( With a load of 0.5%, the removal rate was significantly increased to 80.9 ± 0.1% (e.g., Figure 3 (as shown in a). With The load increased from 0.05% to 1%. The removal rate increased from 41.7±2.0% to 91.7±0.2% (e.g. Figure 4 (As shown).
[0120] In simulated wastewater 1, TLPC was used for... The removal rate of TLPC is significantly affected by pH: within the pH range of 5.0–8.5, the removal rate of TLPC is significantly affected by pH. The removal rate increases with increasing pH; such as Figure 5 As shown, the zero charge point (pHpzc) of TLPC is 7.0. At pH 5.0, the TLPC surface is positively charged, leading to... The adsorption capacity is low. As the pH increases, the –COOH and –OH functional groups are deprotonated, which enhances the electrostatic adsorption capacity of TLPC.
[0121] In simulated wastewater 1, -TLPC pair The removal rate is almost unaffected by pH; - The zero charge point (pHpzc) of TLPC is approximately 8.5. -TLPC surfaces have a higher positive charge, yet they can still remove [products] efficiently. ,illustrate - The adsorption mechanism of TLPC mainly depends on, for example, Figure 6 The oxygen and nitrogen functional groups shown are inner-shell coordination, rather than simple electrostatic interactions;
[0122] Considering both cost and performance, subsequent experiments will use 0.5%. load -TLPC; such as Figure 3 As shown in b, under the condition of pH 7.0, - The maximum adsorption capacity of TLPC ( The concentration of 45.1 mg / g was significantly higher than that of TLPC (11.5 mg / g).
[0123] (2) Characterization of adsorption effect in simulated wastewater 2 (nickel complexed with nickel + triethanolamine + tetraethylenepentamine):
[0124] In simulated wastewater 2, such as Figure 7 As shown in a, TLPC pairs The adsorption effect of TLPC is significantly correlated with pH. The adsorption effect is best at pH 11.0 (nickel removal rate is about 76%).
[0125] In simulated wastewater 2, -TLPC pair The adsorption effect is not significantly related to pH; it is most effective when the pH value is between 5 and 11. -TLPC all maintained a high level The adsorption effect is such that the nickel removal rate is between 66% and 76%; Figure 7 As shown in b, under the condition of pH 11.0, -TLPC pair Maximum adsorption capacity ( The concentration was 7 mg / g, significantly higher than that of TLPC. The maximum adsorption capacity is 4.5 mg / g.
[0126] (3) Characterization of adsorption effect in actual wastewater:
[0127] like Figure 8 As shown in Figure a, for example, when the dosage is 20 g / L, The nickel removal rate of TLPC was 56.0±0.8%, and that of TLPC was 62.7±0.8%. Experimental results show that TLPC and... - TLPC can effectively remove nickel from real electroplating wastewater, and its removal efficiency increases with the increase of adsorbent dosage;
[0128] like Figure 8 As shown in b, TLPC also has a significant removal effect on nickel coordinated in organic matter, and -TLPC has a weak effect on removing coordinated nickel from organic matter;
[0129] Overall, these results support TLPC and -TLPC has the potential to be used as a nickel adsorbent in real alkaline wastewater, especially when nickel exists in an organic coordination state.
[0130] III. Testing the reusability of the adsorbent:
[0131] To test the reusability of TLPC, a value of 0.1 was used. The adsorbed nickel was eluted, and the desorption efficiency was determined by ICP-MS. The regenerated adsorbent was reused five times. Adsorption experiments with organically coordinated nickel; due to acid washing leading to -Leaching of Mn in TLPC, therefore its reusability was not tested; such as Figure 8 As shown in c, TLPC exhibits excellent renewability and stability after acid washing ( After desorption, the nickel removal rate remained at approximately 80% for five consecutive adsorption-desorption cycles, indicating that the active sites could be effectively restored.
[0132] The TLPC of the present invention and -TLPC can also be used for the adsorption of heavy metals in wastewater other than electroplating wastewater.
Claims
1. A method for preparing a thin-layer porous biomass carbon adsorbent, characterized in that, Includes the following steps: Step 1: Collect biomass materials and clean and dry them; Step 2: Grind the cleaned and dried biomass material into powder with a particle size of 0.1–0.6 mm; Step 3: Mix the ground biomass powder with a nitric acid solution with a concentration of 1.1–2.1 M to form a mixed suspension of biomass powder and nitric acid; Step 4: Chemically strip the biomass powder: The mixture of biomass powder and nitric acid is reacted at a temperature of 70-120 °C and a pressure of 31-199 kPa for a set time. Step 5: Filter the reaction product from step 4 and dry the filtered solid powder. Step 6: Place the dried solid powder in a nitrogen atmosphere, heat it to the target temperature at a set heating rate, and calcine it at the target temperature for a set time to obtain the calcined powder. Step 7: Wash the calcined powder with deionized water until neutral, then dry it at 45-60 ℃ and store it in a sealed container.
2. The method according to claim 1, characterized in that: The biomass materials collected in step 1 include bamboo, eggshells, coconut shells, straw, peanut shells, rice husks, and wood; The bamboo collected was 2 to 7 years old.
3. The method according to claim 2, characterized in that, Steps 1 to 7 are as follows: Step 1: Collect bamboo that is 3 to 4 years old, and clean and dry it. Step 2: Use a grinder to grind the cleaned and dried bamboo into powder with a particle size of 0.2 to 0.4 mm; Step 3: Mix the ground bamboo powder with a 1.1-1.6 M nitric acid solution at a ratio of 2.5 L of nitric acid solution to 1 kg of bamboo powder to form a mixed suspension of bamboo powder and nitric acid. Step 4: Chemically exfoliate the bamboo powder: In a high-pressure reactor, react the bamboo powder and nitric acid suspension at a temperature of 70-120 °C and a pressure of 100-170 kPa for 2 h. Step 5: Filter the reaction product from step 4, and dry the filtered solid powder at 100 °C for 24 h using an oven. Step 6: Place the dried solid powder under a nitrogen atmosphere and heat it to 550 ℃ at a heating rate of 5 ℃ / min, and calcine it at the target temperature for 2 h to obtain the calcined powder. Step 7: Wash the calcined powder with deionized water until neutral, then dry it at 45-60 ℃ and store it in a sealed container.
4. A thin-layer porous biomass carbon adsorbent prepared by the method described in claim 3, characterized in that: The thin-layer porous biomass carbon adsorbent has a multi-layered structure with interconnected topologies. Each layer contains micropores with a pore size of 1.5–2.0 nm and a pore volume of 0.18–0.3 cm³. 3 g -1 ; The thin-layer porous biomass carbon adsorbent comprises, by mass percentage, 1.5–6.5 wt% N, 45–66 wt% C and 20–50 wt% O; The specific surface area of the thin-layer porous biomass carbon adsorbent is 400–600 m². 2 / g.
5. A method for applying the thin-layer porous biomass carbon adsorbent as described in claim 4, characterized in that: The thin-layer porous biomass carbon adsorbent was used as an adsorbent for nickel in organic complexed nickel wastewater with a pH of 11 and a nickel concentration of less than 100 mg / L.
6. A kind A method for preparing modified thin-layer porous biomass carbon adsorbent, characterized in that, Includes the following steps: Step 1: Collect biomass materials and clean and dry them; Step 2: Grind the cleaned and dried biomass material into powder with a particle size of 0.1–0.6 mm; Step 3: Mix the ground biomass powder with a nitric acid solution with a concentration of 1.1–2.1 M to form a mixed suspension of biomass powder and nitric acid; Step 4: Chemically strip the biomass powder: The mixture of biomass powder and nitric acid is reacted at a temperature of 70-120 °C and a pressure of 31-199 kPa for a set time. Step 5: Filter the reaction product from step 4 and dry the filtered solid powder. Step 6: Place the dried solid powder in a nitrogen atmosphere, heat it to the target temperature at a set heating rate, and calcine it at the target temperature for a set time to obtain the calcined powder. Step 7: Wash the calcined powder with deionized water until neutral, and then dry it at 45-60 °C to obtain a thin-layer porous biomass carbon adsorbent. Step 8: Use a microwave-assisted method to process the thin-layer porous biomass carbon adsorbent. Modification: Weigh out the following according to the ratio of (0.1~2):
1. The thin-layer porous biomass carbon adsorbent obtained in step 7 will be weighed out. The thin-layer porous biomass carbon adsorbent was mixed together with deionized water, and the ratio of the amount of deionized water used to the amount of thin-layer porous biomass carbon adsorbent weighed was 1 g : 10 ml. The resulting mixture was heated with a microwave of 600-1200 W for 20-60 seconds, stirred evenly, and then microwave heated for another 1.5-5 minutes to obtain the expanded product. Step 9: Dry the puffed product at 60–80 °C for 10–24 h to obtain... Modified thin-layer porous biomass carbon adsorbent, stored in a sealed container.
7. The method according to claim 6, characterized in that: The biomass materials collected in step 1 include bamboo, eggshells, coconut shells, straw, peanut shells, rice husks, and wood; The bamboo collected was 2 to 7 years old.
8. The method according to claim 7, characterized in that, Steps 1 to 9 are as follows: Step 1: Collect bamboo that is 3 to 4 years old, and clean and dry it. Step 2: Use a grinder to grind the cleaned and dried bamboo into powder with a particle size of 0.2 to 0.4 mm; Step 3: Mix the ground bamboo powder with a 1.1-1.6 M nitric acid solution at a ratio of 2.5 L of nitric acid solution to 1 kg of bamboo powder to form a mixed suspension of bamboo powder and nitric acid. Step 4: Chemically exfoliate the bamboo powder: In a high-pressure reactor, react the bamboo powder and nitric acid suspension at a temperature of 70-120 °C and a pressure of 100-170 kPa for 2 h. Step 5: Filter the reaction product from step 4, and dry the filtered solid powder at 100 °C for 24 h using an oven. Step 6: Place the dried solid powder under a nitrogen atmosphere and heat it to 550 ℃ at a heating rate of 5 ℃ / min, and calcine it at the target temperature for 2 h to obtain the calcined powder. Step 7: Wash the calcined powder with deionized water until neutral, then dry it at 45-60 ℃ and store it in a sealed container; Step 8: Use a microwave-assisted method to process the thin-layer porous biomass carbon adsorbent. Modification: Weigh KnMO4 and the thin-layer porous biomass carbon adsorbent prepared in step 7 according to a ratio of (0.1~2):
1. It is mixed with thin-layer porous biomass carbon adsorbent in deionized water; The mixture was heated in a microwave oven at 800 W for 30 seconds, stirred until homogeneous, and then microwaved for another 2 minutes to obtain the puffed product. Step 9: Dry the puffed product at 80 °C for 12 h to obtain... Modified thin-layer porous biomass carbon adsorbent, stored in a sealed container.
9. A product prepared using the method described in claim 8 The modified thin-layer porous biomass carbon adsorbent is characterized by: The The modified thin-layer porous biomass carbon adsorbent has a multi-layered structure at its microscopic level, on which micron-sized particles are deposited. The particles are topologically interconnected, with each layer possessing micropores; wherein the micropores have a pore size of 1.5–2.0 nm and a pore volume of 0.18–0.3 cm³. 3 g -1 ; In terms of mass percentage, the The modified thin-layer porous biomass carbon adsorbent comprises 1.3–6.2 wt% N, 43–62 wt% C, 21–52 wt% O and 0.5–1 wt% Mn; The The modified thin-layer porous biomass carbon adsorbent has a specific surface area of 400–600 m². 2 / g.
10. A device as described in claim 9 The method for applying the modified thin-layer porous biomass carbon adsorbent is characterized by: The Modified thin-layer porous biomass carbon adsorbents were used as nickel adsorbents in inorganic nickel wastewater with a pH value of 5–8.
5. Or the above Modified thin-layer porous biomass carbon adsorbents were used as nickel adsorbents in organic complex nickel wastewater with a pH of 5–11.