Preparation method of a biomimetic flocculant for benzene ring drug wastewater treatment

Abstract

This invention discloses a method for preparing a biomimetic flocculant for treating wastewater containing benzene ring drugs. The flocculant is composed of polydopamine and chitosan. The preparation method involves adding chitosan to pure water in a sealed bottle, dissolving it by adding glacial acetic acid and heating and stirring overnight; dissolving dopamine in another portion of pure water and then adding it to the dissolved chitosan solution; adjusting the pH of the chitosan and dopamine mixture to a weakly alkaline state using sodium hydroxide and hydrochloric acid solutions; continuously purging the mixture with nitrogen gas to remove oxygen, immediately sealing the bottle, and then ultrasonically treating it in an ultrasonic cleaner. After adding a photoinitiator, nitrogen gas is purged again, followed by water bath heating and irradiation under low-pressure ultraviolet light; after irradiation, the mixture is washed alternately with ethanol and pure water, centrifuged, and freeze-dried to prepare the chitosan@polydopamine flocculant. This invention is an environmentally friendly flocculant with good removal efficiency for benzene ring drugs in wastewater, achieving cost reduction and efficiency improvement in practical applications.

Description

Technical Field

[0001] This invention belongs to the field of flocculant preparation technology, specifically relating to a biomimetic flocculant preparation method for treating wastewater containing benzene ring drugs. Background Technology

[0002] With the improvement of people's living standards and the continuous advancement of medical technology, the amount of pharmaceutical waste discharged into the environment as pollutants is increasing every year. Most pharmaceutical waste includes antibiotics, anti-inflammatory drugs, analgesics, synthetic hormones, statins, steroids, antidepressants, antipyretics, stimulants, and antibacterial and disinfectant compounds. The immunosuppressive, bioaccumulative, mutagenic, and genotoxic effects of these drugs can adversely affect human and ecological health. Currently, methods for treating pharmaceuticals in wastewater include biological, aerobic, and anaerobic digestion, fluid dynamic cavitation, bactericidal ultraviolet treatment, chemical treatment, and physical treatment. Different methods are suitable for different pharmaceutical situations. With increasingly stringent environmental protection requirements, exploring efficient, low-consumption, safe, and harmless treatment methods is currently a research hotspot.

[0003] The antibacterial activity of antibiotics and anti-inflammatory drugs is primarily attributed to their complex aromatic structures. These compounds are difficult to degrade naturally under light and oxidative conditions. In treating wastewater containing benzene ring drugs, coagulation exhibits significant advantages over other methods in terms of economy, convenience, and ease of operation. However, traditional flocculants, such as polyacrylamide, are prone to aggregation in aquatic environments due to the weak internal charge repulsion of their molecular chains. This not only reduces coagulation efficiency but also leaves acrylamide residues, a potential carcinogen that poses a threat to human health.

[0004] Chinese patent application CN202411009103.4, entitled "A Nanomagnetic Flocculant and Its Preparation Method and Application," discloses a nanomagnetic flocculant for efficiently removing trace amounts of sulfonamide antibiotics from drinking water sources and its preparation method. Although the preparation method of this flocculant is simple and easy to implement, it relies on a variety of chemical reagents. These reagents not only increase production costs, but the environmental byproducts generated during their use and preparation also have potential impacts on the ecological environment.

[0005] Chinese patent application number CN202410472728.8, entitled "Preparation method and use of a polymeric zirconium oxychloride inorganic polymeric flocculant", discloses a polymeric zirconium oxychloride flocculant and its preparation method for effectively removing quinolone antibiotics from water. The flocs formed are large in size, have a fast sedimentation rate, and good settling performance. However, the preparation process has a long production cycle and requires high corrosion resistance and operational precision of the production equipment, which increases the difficulty and cost of practical application.

[0006] Therefore, it is essential to develop a new type of flocculant that is simple to prepare, has mild preparation conditions, excellent removal effect, low cost, and is environmentally friendly. Summary of the Invention

[0007] In view of the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing a biomimetic flocculant for the treatment of benzene ring drug wastewater.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] Chitosan was added to pure water and placed in a sealed bottle. It was dissolved overnight by adding glacial acetic acid and heating with stirring. Dopamine was dissolved in another portion of pure water and then poured into the dissolved chitosan solution. The pH of the chitosan and dopamine mixture was adjusted to a weakly alkaline state using sodium hydroxide and hydrochloric acid solutions. Nitrogen gas was continuously purged into the mixture for 15 minutes, and the bottle was immediately sealed. The mixture was then ultrasonically treated for 5 minutes in an ultrasonic cleaner. After adding a photoinitiator, nitrogen gas was purged again for 15 minutes. Subsequently, the mixture was heated in a water bath while being irradiated under a low-pressure ultraviolet lamp. After irradiation, the mixture was washed alternately with ethanol and pure water, centrifuged, and freeze-dried for 2 days to prepare the chitosan@polydopamine flocculant.

[0010] Specifically, the following steps are included:

[0011] (1) Prepare a chitosan solution with a concentration of 40wt% to 50wt%. Add chitosan to pure water and place it in a sealed bottle. Dissolve the chitosan by adding glacial acetic acid dropwise and heating and stirring overnight.

[0012] (2) Prepare a dopamine solution with a concentration of 50wt% to 60wt%. Dissolve the dopamine in another part of pure water and then pour it into the dissolved chitosan solution. The mass ratio of chitosan to dopamine is 1:1 to 1.5.

[0013] (3) Use 1 mol / L sodium hydroxide and hydrochloric acid solution to adjust the pH of the chitosan and dopamine mixture to a weakly alkaline state of 7.5-8.

[0014] (4) After continuously introducing nitrogen into the mixture for 15 minutes, seal the container immediately, place it in an ultrasonic cleaner for 5 minutes of ultrasonic treatment, add 0.1% to 0.2% V-50 photoinitiator, and then introduce nitrogen again for 15 minutes. Subsequently, heat it in a water bath at 30°C to 40°C while irradiating it under a 50-watt low-pressure ultraviolet lamp for 90 to 120 minutes.

[0015] (5) After irradiation, the chitosan@polydopamine biomimetic flocculant can be prepared by alternating washing and centrifugation with ethanol and pure water, and freeze-drying for 2 days. It can be ground into powder for later use.

[0016] In step (2), the mass ratio of chitosan to dopamine is 1:1 to 1.5. When there is too little dopamine, the chitosan is not fully modified, the pH environment is still harsh, and the flocculation effect is poor. When there is too much dopamine, the branches become too long, competing for the active sites that chitosan originally had to react with ibuprofen. At the same time, excessive self-aggregation of dopamine makes the prepared flocculant difficult to dissolve.

[0017] In step (3), the pH of the chitosan and dopamine mixture is adjusted to 7.5–8. If the pH is too low, the reaction conditions for the Shiff base reaction will not be met. If the pH is too high, it may cause chitosan molecule degradation and excessive dopamine self-polymerization.

[0018] In step (4), the content of V-50 photoinitiator is controlled to be between 0.1% and 0.2%. When the amount of initiator added is too small, the number of active free radicals generated is limited, which reduces the polymerization rate and the molecular structure of chitosan@polydopamine flocculant is not perfect. When the amount of initiator added is too large, there are too many active free radicals, the polymerization reaction is violent, and dopamine undergoes excessive self-polymerization.

[0019] In step (4), the water bath heating temperature is controlled to be 30℃~40℃. When the temperature is too low, the viscosity of the water will increase, which will increase the resistance between molecules, thus hindering the full mixing and reaction of chitosan and polydopamine molecules. When the temperature is too high, chitosan, a biopolymer, may decompose and lose its original flocculation properties; dopamine may also undergo structural changes.

[0020] The process described in step (4) involves irradiation under low-pressure ultraviolet light for 90 to 120 minutes. If the irradiation time is too short, the synthesized flocculant will have a low intrinsic viscosity, incomplete graft polymerization, and low grafting efficiency. If the irradiation time is too long, ultraviolet light irradiation may cause the already generated graft copolymer to undergo a disproportionation reaction, resulting in products with unstable structures or poor performance.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The biomimetic flocculant prepared by this invention is biodegradable and non-toxic, effectively overcoming the shortcomings of organic and inorganic flocculants, such as residual monomers being biologically harmful and causing secondary environmental pollution, thus improving biosafety and environmental friendliness.

[0023] 2. The biomimetic flocculant prepared by this method can not only remove pollutants from conventional water treatment, but also remove non-steroidal anti-inflammatory drugs such as ibuprofen that cannot be removed by conventional methods. This can improve the effluent quality of sewage treatment plants and meet stricter water quality standards.

[0024] 3. By using biomimetic flocculants, the dosage of conventional inorganic and organic flocculants can be reduced, thereby lowering the operating costs of municipal wastewater treatment plants. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments. Unless otherwise specified, the raw materials used in the embodiments are ordinary commercially available products.

[0026] Example 1:

[0027] (1) Prepare a 50wt% chitosan solution by adding chitosan to pure water and placing it in a sealed bottle, then dissolving it by adding glacial acetic acid and heating and stirring overnight.

[0028] (2) Prepare a 50wt% dopamine solution. Dissolve the dopamine in another portion of pure water by stirring, and then pour it into the dissolved chitosan solution.

[0029] (3) Use 1 mol / L sodium hydroxide and hydrochloric acid solution to adjust the pH of the chitosan and dopamine mixture to a weakly alkaline 7.5.

[0030] (4) After continuously introducing nitrogen into the mixture for 15 minutes, seal the container immediately, place it in an ultrasonic cleaner for 5 minutes of ultrasonic treatment, add 0.1% V-50 photoinitiator, and then introduce nitrogen again for 15 minutes. Subsequently, heat it in a 30°C water bath while irradiating it under a 50W low-pressure ultraviolet lamp for 90 minutes.

[0031] (5) After irradiation, the chitosan@polydopamine flocculant can be prepared by alternating washing and centrifugation with ethanol and pure water and freeze-drying for 2 days.

[0032] Example 2:

[0033] (1) Prepare a 50wt% chitosan solution by adding chitosan to pure water and placing it in a sealed bottle, then dissolving it by adding glacial acetic acid and heating and stirring overnight.

[0034] (2) Prepare a 50wt% dopamine solution. Dissolve the dopamine in another portion of pure water by stirring, and then pour it into the dissolved chitosan solution.

[0035] (3) Use 1 mol / L sodium hydroxide and hydrochloric acid solution to adjust the pH of the chitosan and dopamine mixture to a weakly alkaline 7.5.

[0036] (4) After continuously introducing nitrogen into the mixture for 15 minutes, seal the container immediately, place it in an ultrasonic cleaner for 5 minutes of ultrasonic treatment, add 0.1% V-50 photoinitiator, and then introduce nitrogen again for 15 minutes. Subsequently, heat it in a 40°C water bath while irradiating it under a 50W low-pressure ultraviolet lamp for 90 minutes.

[0037] (5) After irradiation, the chitosan@polydopamine flocculant can be prepared by alternating washing and centrifugation with ethanol and pure water and freeze-drying for 2 days.

[0038] Example 3:

[0039] (1) Prepare a 50wt% chitosan solution by adding chitosan to pure water and placing it in a sealed bottle, then dissolving it by adding glacial acetic acid and heating and stirring overnight.

[0040] (2) Prepare a 50wt% dopamine solution. Dissolve the dopamine in another portion of pure water by stirring, and then pour it into the dissolved chitosan solution.

[0041] (3) Use 1 mol / L sodium hydroxide and hydrochloric acid solution to adjust the pH of the chitosan and dopamine mixture to a weakly alkaline 8.

[0042] (4) After continuously introducing nitrogen into the mixture for 15 minutes, seal the container immediately, place it in an ultrasonic cleaner for 5 minutes of ultrasonic treatment, add 0.1% V-50 photoinitiator, and then introduce nitrogen again for 15 minutes. Subsequently, heat it in a 40°C water bath while irradiating it under a 50W low-pressure ultraviolet lamp for 90 minutes.

[0043] (5) After irradiation, the chitosan@polydopamine flocculant can be prepared by alternating washing and centrifugation with ethanol and pure water and freeze-drying for 2 days.

[0044] Example 4:

[0045] (1) Prepare a 50wt% chitosan solution by adding chitosan to pure water and placing it in a sealed bottle, then dissolving it by adding glacial acetic acid and heating and stirring overnight.

[0046] (2) Prepare a 50wt% dopamine solution. Dissolve the dopamine in another portion of pure water by stirring, and then pour it into the dissolved chitosan solution.

[0047] (3) Use 1 mol / L sodium hydroxide and hydrochloric acid solution to adjust the pH of the chitosan and dopamine mixture to a weakly alkaline 8.

[0048] (4) After continuously introducing nitrogen into the mixture for 15 minutes, seal the container immediately, place it in an ultrasonic cleaner for 5 minutes of ultrasonic treatment, add 0.1% V-50 photoinitiator, and then introduce nitrogen again for 15 minutes. Subsequently, heat it in a 40°C water bath while irradiating it under a 50W low-pressure ultraviolet lamp for 120 minutes.

[0049] (5) After irradiation, the chitosan@polydopamine flocculant can be prepared by alternating washing and centrifugation with ethanol and pure water and freeze-drying for 2 days.

[0050] Example 5:

[0051] (1) Prepare a 50wt% chitosan solution by adding chitosan to pure water and placing it in a sealed bottle, then dissolving it by adding glacial acetic acid and heating and stirring overnight.

[0052] (2) Prepare a 50wt% dopamine solution. Dissolve the dopamine in another portion of pure water by stirring, and then pour it into the dissolved chitosan solution.

[0053] (3) Use 1 mol / L sodium hydroxide and hydrochloric acid solution to adjust the pH of the chitosan and dopamine mixture to a weakly alkaline 8.

[0054] (4) After continuously introducing nitrogen into the mixture for 15 minutes, seal the container immediately, place it in an ultrasonic cleaner for 5 minutes of ultrasonic treatment, add 0.1% V-50 photoinitiator, and then introduce nitrogen again for 15 minutes. Subsequently, heat it in a 40°C water bath while irradiating it under a 50W low-pressure ultraviolet lamp for 120 minutes.

[0055] (5) After irradiation, the chitosan@polydopamine flocculant can be prepared by alternating washing and centrifugation with ethanol and pure water and freeze-drying for 2 days.

[0056] Example 6:

[0057] (1) Prepare a 50wt% chitosan solution by adding chitosan to pure water and placing it in a sealed bottle, then dissolving it by adding glacial acetic acid and heating and stirring overnight.

[0058] (2) Prepare a 50wt% dopamine solution. Dissolve the dopamine in another portion of pure water by stirring, and then pour it into the dissolved chitosan solution.

[0059] (3) Use 1 mol / L sodium hydroxide and hydrochloric acid solution to adjust the pH of the chitosan and dopamine mixture to a weakly alkaline 8.

[0060] (4) After continuously introducing nitrogen into the mixture for 15 minutes, seal the container immediately, place it in an ultrasonic cleaner for 5 minutes of ultrasonic treatment, add 0.2% V-50 photoinitiator, and then introduce nitrogen again for 15 minutes. Subsequently, heat it in a 40°C water bath while irradiating it under a 50W low-pressure ultraviolet lamp for 120 minutes.

[0061] (5) After irradiation, the chitosan@polydopamine flocculant can be prepared by alternating washing and centrifugation with ethanol and pure water and freeze-drying for 2 days.

[0062] The relevant properties of the novel biomimetic flocculants prepared in Examples 1 to 6 were determined respectively, and the data are detailed in Table 1.

[0063] Table 1. Relevant Properties of Bionic Flocculants

[0064] product Ibuprofen removal rate (%) Example 1 85.13 Example 2 86.60 Example 3 88.23 Example 4 90.33 Example 5 90.59 Example 6 89.68

[0065] As can be seen from Table 1 above, the biomimetic flocculant product prepared by this invention exhibits excellent and stable performance. It not only enhances the removal effect of ibuprofen but also possesses environmentally friendly and non-toxic characteristics, with minimal impact on aquatic organisms and the ecological environment. This demonstrates that this is a practical and effective method for preparing biomimetic flocculants.

[0066] Finally, it should be noted that the above embodiments of the present invention are merely illustrative examples and not intended to limit the implementation of the invention. Those skilled in the art can make other variations and modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of this invention are still within the scope of protection of this invention.

Claims

1. A method for preparing a biomimetic flocculant for treating wastewater from benzene ring drugs, characterized in that, To prepare a chitosan solution with a concentration of 40wt% to 50wt%, add chitosan to pure water in a sealed bottle and dissolve it by adding glacial acetic acid dropwise while heating and stirring overnight. To prepare a dopamine solution with a concentration of 50wt% to 60wt%, dissolve dopamine in another portion of pure water by stirring, and then pour it into the dissolved chitosan solution. The pH of the chitosan and dopamine mixture was adjusted to a weakly alkaline state of 7.5–8 using a 1 mol / L sodium hydroxide and hydrochloric acid solution. Nitrogen gas was continuously introduced into the mixture for 15 minutes, and the mixture was immediately sealed. It was then ultrasonically treated for 5 minutes in an ultrasonic cleaner. After adding 0.1%–0.2% V-50 photoinitiator, nitrogen gas was introduced again for 15 minutes. Subsequently, the mixture was heated in a water bath at 30°C–40°C while being irradiated under a 50-watt low-pressure ultraviolet lamp for 90–120 minutes. After irradiation, the mixture was washed and centrifuged alternately with ethanol and pure water, and then freeze-dried for 2 days to prepare the chitosan@polydopamine biomimetic flocculant, which was then ground into powder for later use.

2. The method for preparing the biomimetic flocculant for treating benzene ring drug wastewater according to claim 1, characterized in that, The mass ratio of chitosan to dopamine is 1:1 to 1.5.