Method for removing antibiotics in water by activated sodium sulfite with false ragweed biochar

Abstract

The application discloses a kind of false smelly grass biochar activated sodium sulfite to remove antibiotic in water with waste treatment method, belong to water treatment technology and biomass resource field.The application uses invasive plant false smelly grass as raw material, and porous biochar is prepared by limited oxygen pyrolysis, and the biochar is compounded and added to antibiotic-containing wastewater with sodium sulfite.The application utilizes the porous structure of biochar to quickly adsorb and enrich antibiotic molecules, and simultaneously utilizes the persistent free radicals, oxygen-containing functional groups and carbon defect sites on the surface of biochar as electron donors to efficiently activate sodium sulfite to generate sulfate radicals and hydroxyl radicals, and realizes the deep mineralization of antibiotics through the "adsorption enrichment-in-situ oxidative degradation" synergistic mechanism.The application is run at normal temperature and pressure without metal catalysis throughout, and the removal rate of tetracycline can reach 99.07%, which not only realizes the resource utilization of invasive plant false smelly grass, but also efficiently solves the problem of water body antibiotic pollution, with the advantages of high treatment efficiency, green environmental protection, low cost, simple process and the like.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology and biomass resource utilization, specifically relating to a method for removing antibiotics from water by activating sodium sulfite with *Pseudostoma spp.* biochar. Background Technology

[0002] Livestock and poultry farming, pharmaceutical production, and routine medical activities continuously generate wastewater containing antibiotics. Antibiotics have stable chemical structures, are difficult to degrade naturally, and exhibit strong persistence in the aquatic environment. Long-term residues can easily promote the development of drug-resistant genes in aquatic microorganisms, disrupt the aquatic ecological balance, and pose a potential threat to human health through bioaccumulation. Therefore, the efficient removal of antibiotic residues from water bodies is of great practical significance.

[0003] Current water antibiotic treatment technologies still have many shortcomings. Conventional biological treatment processes have limited ability to degrade stubborn organic pollutants, making it difficult to meet the requirements for deep treatment of low-concentration, highly stable antibiotics. Traditional physical adsorption methods can only achieve the transfer of antibiotics from the aqueous phase to the solid phase, but cannot completely decompose pollutants. Adsorption saturation materials are prone to secondary pollution, and the treatment effect is limited. Conventional advanced oxidation technologies mostly rely on metal catalysis, photoactivation, or thermal activation, which have problems such as poor catalyst stability, risk of metal leaching, high energy consumption, and high operating costs, thus limiting their engineering applicability.

[0004] Sulfite advanced oxidation systems are environmentally friendly, use readily available raw materials, and have low treatment costs. After activation, they can generate highly oxidizing free radicals that can effectively degrade organic pollutants in water. However, sulfite currently suffers from technical drawbacks such as insufficient activation efficiency, weak reaction system stability, and high energy consumption under conventional activation conditions, which limit its large-scale application in the treatment of antibiotic wastewater.

[0005] False stink grass is a typical invasive alien plant in southeastern my country. It has a strong reproductive capacity and a wide spread, seriously crowding out the living space of native plants and damaging regional biodiversity. At present, the control of false stink grass is mainly based on manual removal, mechanical removal or chemical control. The biomass waste after removal lacks effective resource utilization methods and is mostly directly abandoned or landfilled, which not only wastes biomass resources but also easily creates subsequent environmental disposal pressure.

[0006] In summary, existing antibiotic wastewater treatment processes suffer from limited treatment efficiency, high operating costs, and the risk of secondary pollution. Furthermore, the invasive plant *Pseudostigma sarmentosum* presents a technological gap due to its low resource utilization rate and insufficient added value from treatment. Therefore, developing a treatment technology that utilizes invasive plant biomass to prepare functional materials, employs a metal-free catalyst, is simple to process, and can simultaneously achieve solid waste resource utilization and efficient antibiotic degradation in water bodies has promising application prospects and ecological value. Summary of the Invention

[0007] In view of this, the purpose of this invention is to provide a waste-to-waste method for removing antibiotics from water by activating sodium sulfite with *Pseudolarix amabilis* biochar. This invention uses the invasive plant *Pseudolarix amabilis* as raw material and prepares porous biochar through oxygen-limited low-temperature pyrolysis. Utilizing the porous structure, oxygen-containing functional groups, and surface defect sites on the surface of the biochar, a metal-free synergistic treatment system is constructed that couples biochar adsorption with advanced oxidation of sulfite, thereby achieving efficient removal and deep degradation of antibiotics in water.

[0008] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for removing antibiotics from water by activating sodium sulfite with *Pseudolarix amabilis* biochar, comprising the following steps: (1) The raw material of false stinky grass is pretreated by washing, drying and crushing; (2) Under an inert atmosphere, the pretreated false stinky grass powder was pyrolyzed to obtain false stinky grass biochar; (3) Add false stinky grass biochar and sodium sulfite to the water containing antibiotics to construct a reaction system. Stir the reaction under normal temperature and pressure to allow the antibiotics to be adsorbed, enriched and oxidized and degraded. (4) After the reaction is complete, solid-liquid separation is performed to obtain purified effluent.

[0009] Preferably, the drying in step (1) involves drying the biochar at 80-100°C in a constant temperature drying oven until constant weight. The collected stems and leaves of the pseudo-stink grass contain mud, dead branches, and particulate impurities of varying sizes. If directly pyrolyzed, these impurities will clog the biochar pores, and the uneven particle size will lead to uneven heat and mass transfer during pyrolysis, ultimately resulting in poor development of the biochar pore structure and unstable performance. Therefore, the inorganic minerals and impurities attached to the surface are removed by rinsing with clean water, and the internal free water and bound water are removed by drying at 80-100°C (to avoid the sudden release of water vapor during pyrolysis that could cause structural collapse). The biochar is then pulverized and sieved to obtain uniform and fine biomass powder (preferably with a particle size of 20-60 mesh), ensuring uniform heating and consistent volatile matter release channels during subsequent pyrolysis, thereby forming a porous carbon material with a uniform structure and stable performance.

[0010] Preferably, the pyrolysis temperature in step (2) is 500-800 ℃.

[0011] Preferably, the heating rate of the pyrolysis in step (2) is 5~10℃ / min, and the isothermal pyrolysis time is 2~3 h.

[0012] Preferably, the inert atmosphere in step (2) is a nitrogen atmosphere, and the nitrogen flow rate is 100 mL / min.

[0013] Oxygen-limited pyrolysis under an inert atmosphere such as nitrogen aims to prevent complete combustion of biomass at high temperatures, instead inducing thermochemical transformation. Within a temperature range of 500–800℃, cellulose, hemicellulose, and lignin in *Pseudolarix amabilis* undergo dehydroxylation, decarboxylation, and aromatization reactions, gradually transforming into compounds with sp... 2 The graphite-like microcrystalline structure of the hybrid carbon framework endows the *Pseudostoma spp.* biochar with both excellent adsorption properties and intrinsic catalytic activity without metal doping, laying the material foundation for subsequent activation of sodium sulfite. The parameters of a heating rate of 5–10 °C / min and a holding time of 2–3 h are limited to control the rate of volatile matter release, avoiding either excessively rapid heating leading to pore collapse or excessively slow heating leading to high energy consumption, thus ensuring optimal performance of the char material.

[0014] Preferably, the mass ratio of the pseudo-stink grass biochar to sodium sulfite in step (3) is 1:(2.5~5).

[0015] Preferably, the concentration of sodium sulfite in the reaction system in step (3) is 1 mmol / L.

[0016] Preferably, the stirring reaction time in step (3) is 120~160 min.

[0017] Preferably, the reaction system described in step (3) is operated under natural pH conditions.

[0018] Preferably, the amount of *Pseudostoma styracifolium* biochar added to the reaction system in step (3) is 0.5~1 g / L.

[0019] Preferably, the antibiotic is a tetracycline antibiotic.

[0020] It contains at least the following beneficial technical effects: This invention relies on the synergistic effect of adsorption-catalytic oxidation to rapidly enrich and deeply degrade tetracycline, achieving a removal rate of up to 99.07% under optimal conditions. This treatment effect is significantly superior to single adsorption or single sodium sulfite oxidation systems, enabling effective mineralization of pollutants. The entire process utilizes a metal-free catalytic system, eliminating the risk of metal ion leaching. The reaction byproduct is harmless sulfate, and the biochar material is stable. Simultaneously, invasive plants are transformed into functional materials, achieving both the harmlessness and resource utilization of solid waste, truly realizing waste-to-waste treatment. The core raw material, *Pseudolarix amabilis*, is a ubiquitous invasive weed, resulting in extremely low collection costs; sodium sulfite is inexpensive and readily available. The overall cost of reagents and materials is far lower than traditional advanced oxidation processes, demonstrating outstanding economic efficiency. The reaction is carried out at ambient temperature and pressure, requiring no special conditions such as light, high temperature, or high pressure. It requires minimal equipment and has a simple operation process, making it suitable for small-scale decentralized wastewater treatment facilities as well as large and medium-sized water treatment projects and aquatic ecological restoration scenarios. The prepared biochar exhibits stable catalytic performance and a continuously efficient reaction system. It is capable of treating various antibiotics such as tetracycline, sulfonamides, and quinolones, as well as recalcitrant organic pollutants. Its applications can be expanded to include various water bodies such as aquaculture wastewater, pharmaceutical wastewater, and polluted surface water. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope image of biochar from *Pseudostoma spp.* Detailed Implementation

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0025] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0026] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0027] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0028] Unless otherwise specified, all raw materials or instruments used in the following embodiments of the present invention are commercially available.

[0029] Example 1 Preparation of False Stink Grass Biochar Collect the stems and leaves of wild-growing *Pseudocarpus santalinus*, remove mud, dead branches and impurities, and rinse thoroughly with clean water. Place the washed *Pseudocarpus santalinus* in a constant temperature drying oven at 80℃ and dry to constant weight. Crush and sieve the dried material to obtain uniform fine biomass powder, and seal and store for later use.

[0030] 10 g of pretreated *Pseudostoma pseudocapsicum* powder was placed in a quartz crucible and then placed in a tube furnace. High-purity nitrogen gas (flow rate 100 mL / min) was continuously introduced to purge the air from the furnace and maintain an inert protective atmosphere. The temperature was increased to 500℃ at a rate of 5℃ / min and pyrolyzed at 500℃ for 2 h. After pyrolysis, the mixture was naturally cooled to room temperature under nitrogen protection to obtain black porous *Pseudostoma pseudocapsicum* biochar (denoted as SBC500), which was then sealed, dried, and stored.

[0031] Example 2 Adsorption dynamics of tetracycline in water by *Pseudostoma spp.* biochar Take 200 mL of tetracycline solution with an initial concentration of 50 mg / L, add 1 g / L of SBC500 biochar prepared in Example 1, and stir on a magnetic stirrer. Take samples at regular intervals, filter through a 0.45 μm filter membrane, and measure the absorbance of the supernatant at the maximum absorption wavelength of 360 nm to calculate the adsorption rate of tetracycline in water.

[0032] The results show that the entire adsorption process follows pseudo-second-order kinetics, and the fitted equation is:

[0033] (R² = 0.9985; t is the reaction time (min); q) tThe amount of tetracycline adsorbed by biochar at time t (mg·g) -1 ).

[0034] This indicates that the adsorption process is primarily chemisorption, and the number of active sites on the adsorbent surface is the controlling factor for the adsorption rate. This adsorption performance is beneficial for the enrichment and concentration of tetracycline in water, as well as subsequent efficient oxidation removal.

[0035] Figure 1 This is a scanning electron microscope (SEM) image of *Pseudostoma spp.* biochar. SEM characterization results show that the surface of the *Pseudostoma spp.* biochar sheets has natural, fine wrinkles, and the sheets stack together to form a continuous porous network with high porosity. This structure provides a large specific surface area, making it suitable as an adsorbent and catalyst support.

[0036] Example 3 Comparison of the effects of different systems on tetracycline removal from water A solution with an initial tetracycline concentration of 50 mg / L was used to investigate the removal performance of tetracycline from water in the following three systems: (1) SBC500 adsorption system alone: ​​SBC500 0.5 g / L was added; (2) Sodium sulfite oxidation system alone: ​​Add 1 mmol / L of sodium sulfite; (3) Sodium sulfite + SBC500 synergistic system: Add 0.5 g / L of SBC500 and 1 mmol / L of sodium sulfite.

[0037] Each system was stirred and reacted for 140 min under normal temperature and pressure conditions before samples were taken for analysis.

[0038] Conclusion: After 140 min of reaction, the removal rate of SBC500 adsorption alone was 85.05%; the removal rate of sodium sulfite oxidation alone was 80.74%; and the removal rate of the sodium sulfite + SBC500 synergistic system was 99.07%. The results indicate that the sodium sulfite + SBC500 synergistic system exhibits the most significant removal effect due to the coupling of adsorption enrichment and catalytic oxidation.

[0039] Example 4 Effect of different pyrolysis temperatures on biochar performance Following the preparation method of Example 1, pyrolysis temperatures of 500℃, 600℃, 700℃, and 800℃ were set, with a heating rate of 5℃ / min and a constant temperature pyrolysis time of 2 h, to prepare *Pseudostoma styracifolium* biochar at different temperatures.

[0040] Under the same reaction conditions (initial tetracycline concentration 50 mg / L, biochar dosage 0.5 g / L, sodium sulfite concentration 1 mmol / L, reaction time 140 min), the removal efficiency of biochar prepared at different temperatures for tetracycline was investigated. The results showed that biochar prepared in the range of 500–800 °C exhibited good adsorption-catalytic synergistic performance, with biochar prepared at 500 °C showing the best overall performance.

[0041] Example 5 Practical wastewater treatment applications Wastewater from a livestock farm was collected and tested to find tetracycline antibiotic residues. 200 mL of this wastewater was taken, and 0.5 g / L of SBC500 biochar prepared in Example 1 and 1 mmol / L of sodium sulfite were added. The mixture was stirred and reacted for 140 min at room temperature and pressure. After the reaction was complete, the mixture was allowed to settle, and the supernatant was used to determine the antibiotic residue levels.

[0042] The results showed that after treatment by the method of the present invention, the removal rate of tetracycline antibiotics in aquaculture wastewater reached more than 95%, and the effluent quality was significantly improved.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for removing antibiotics from water by activating sodium sulfite with *Pseudolarix amabilis* biochar, characterized in that... Includes the following steps: (1) The raw material of false stinky grass is pretreated by washing, drying and crushing; (2) Under an inert atmosphere, the pretreated false stinky grass powder was pyrolyzed to obtain false stinky grass biochar; (3) Add false stinky grass biochar and sodium sulfite to the water containing antibiotics to construct a reaction system. Stir the reaction under normal temperature and pressure to allow the antibiotics to be adsorbed, enriched and oxidized and degraded. (4) After the reaction is complete, solid-liquid separation is performed to obtain purified effluent.

2. The method according to claim 1, characterized in that, The drying process described in step (1) involves placing the product in a constant temperature drying oven at 80~100℃ and drying it to a constant weight.

3. The method according to claim 1, characterized in that, The pyrolysis temperature in step (2) is 500-800 ℃.

4. The method according to claim 3, characterized in that, The heating rate of the pyrolysis in step (2) is 5~10℃ / min, and the isothermal pyrolysis time is 2~3 h.

5. The method according to claim 1, characterized in that, The mass ratio of the pseudo-stink grass biochar to sodium sulfite in step (3) is 1:(2.5~5).

6. The method according to claim 1, characterized in that, The concentration of sodium sulfite in the reaction system in step (3) is 1 mmol / L.

7. The method according to claim 1, characterized in that, The stirring reaction time in step (3) is 120~160 min.

8. The method according to claim 1, characterized in that, The reaction system described in step (3) is operated under natural pH conditions.

9. The method according to claim 1, characterized in that, The dosage of the pseudo-stink grass biochar in step (3) in the reaction system is 0.5~1 g / L.

10. The method according to claim 1, characterized in that, The antibiotic in question is a tetracycline antibiotic.

Images