Preparation method of bionic flocculant for benzene ring medicine wastewater treatment

Abstract

The invention discloses a preparation method of a bionic flocculant for benzene ring medicine wastewater treatment. The flocculating agent is prepared from polydopamine and chitosan. The preparation method comprises the following steps: adding chitosan into pure water, placing in a sealed bottle, dropwise adding glacial acetic acid, heating and stirring overnight, and dissolving; stirring and dissolving dopamine in the other part of pure water, and pouring into the dissolved chitosan solution; the method comprises the following steps: adjusting the pH value of a mixed solution of chitosan and dopamine to alkalescence by using a sodium hydroxide and hydrochloric acid solution; continuously introducing nitrogen into the mixed solution to expel oxygen, immediately sealing, putting into an ultrasonic cleaning machine for ultrasonic treatment, adding a photoinitiator, introducing nitrogen again, heating in a water bath, and irradiating under low-pressure ultraviolet light at the same time; after irradiation is finished, ethanol and pure water are used for alternately cleaning and centrifuging, freeze drying is conducted, and the chitosan and polydopamine flocculant can be prepared. The flocculant provided by the invention is an environment-friendly flocculant, has a good removal effect on benzene ring drugs in wastewater, and can realize cost reduction and efficiency improvement in practical application.

Description

Technical Field

[0001] The invention belongs to the technical field of flocculant preparation, and in particular relates to a method for preparing a bionic flocculant for treating benzene ring drug wastewater. Background Art

[0002] With the improvement of people's living standards and the continuous advancement of medical standards, more and more drugs are discharged into the environment in the form of pollutants every year. Most pharmaceutical wastes include antibiotics, anti-inflammatory drugs, analgesics, synthetic hormones, statins, steroids, antidepressants, antipyretics, stimulants, antibacterial and disinfectant compounds. The immunosuppression, bioaccumulation, mutagenicity and genotoxicity of drugs can have adverse effects on human and ecological health. Currently, the methods that can be used for drug treatment in wastewater treatment include biological and aerobic and anaerobic digestion, fluid dynamic cavitation, bactericidal ultraviolet treatment, chemical treatment and physical treatment. Different methods are suitable for different drug situations. With the increasing requirements for environmental protection, exploring efficient, low-consumption, safe and harmless treatment methods is the current research hotspot.

[0003] The antimicrobial activity of antibiotic and anti-inflammatory drug compounds is mainly attributed to their complex aromatic structures. These compounds are difficult to degrade naturally under light and oxidation conditions. When treating wastewater containing benzene ring drugs, coagulation shows significant advantages over other methods in terms of economy, convenience and ease of operation. However, traditional flocculants, such as polyacrylamide, are prone to agglomeration in water environments due to the weak charge repulsion within the molecular chain, which not only reduces the coagulation efficiency, but also its residual acrylamide, as a potential carcinogen, poses a threat to human health.

[0004] Chinese patent application number CN202411009103.4, titled "A nanomagnetic flocculant, its preparation method and application", discloses a nanomagnetic flocculant and its preparation method for efficiently removing trace sulfonamide antibiotics from drinking water sources. Although the preparation method of the flocculant is simple and easy, it relies on a variety of chemical reagents, which not only increase the production cost, but also the environmental byproducts accompanying its use and preparation process have potential impacts on the ecological environment.

[0005] Chinese patent application number CN202410472728.8, the invention name is "A preparation method and use of a polysilicate zirconium oxychloride inorganic polymer flocculant", which discloses a polysilicate zirconium oxychloride flocculant and a preparation method for effectively removing quinolone antibiotics in water. The flocs formed by the flocculant are large in size, fast in precipitation speed, and good in sedimentation performance. However, the production cycle is long during the preparation process, and the corrosion resistance and operating precision of the production equipment are high, which increases the difficulty and cost of practical application.

[0006] Therefore, it is very necessary to develop a new flocculant with simple preparation process, mild preparation conditions, excellent removal effect, low cost and environmental friendliness. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing a bionic flocculant for treating benzene ring drug wastewater.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] Chitosan was added into pure water and placed in a sealed bottle. Glacial acetic acid was added dropwise and heated and stirred overnight to dissolve. Dopamine was stirred and dissolved in another portion of pure water and then poured into the dissolved chitosan solution. The pH of the mixed solution of chitosan and dopamine was adjusted to weak alkalinity using sodium hydroxide and hydrochloric acid solutions. Nitrogen was continuously introduced into the mixed solution for 15 minutes and then the mixture was immediately sealed and ultrasonically treated for 5 minutes in an ultrasonic cleaner. After adding a photoinitiator, nitrogen was introduced again for 15 minutes and then the mixture was heated in a water bath and irradiated under a low-pressure ultraviolet light. After the irradiation, the mixture was alternately cleaned and centrifuged using ethanol and pure water and freeze-dried for 2 days to prepare chitosan@polydopamine flocculant.

[0010] The specific steps include:

[0011] (1) A chitosan solution with a concentration of 40 wt% to 50 wt% is prepared. Chitosan is added to pure water and placed in a sealed bottle. Glacial acetic acid is added dropwise and heated and stirred overnight to dissolve.

[0012] (2) A dopamine solution with a concentration of 50 wt% to 60 wt% is prepared, dopamine is stirred and dissolved in another portion of pure water, and then poured into the dissolved chitosan solution, wherein the mass ratio of chitosan to dopamine is 1:1 to 1.5.

[0013] (3) Using 1 mol / L sodium hydroxide and hydrochloric acid solution, the pH of the mixed solution of chitosan and dopamine was adjusted to a weak alkalinity of 7.5 to 8.

[0014] (4) After nitrogen is continuously introduced into the mixed solution for 15 minutes, the mixture is immediately sealed and placed in an ultrasonic cleaner for ultrasonic treatment for 5 minutes. After adding 0.1% to 0.2% V-50 photoinitiator, nitrogen is introduced again for 15 minutes. Subsequently, the mixture is heated in a water bath at 30° C. to 40° C. and irradiated under a 50-W low-pressure ultraviolet lamp for 90 minutes to 120 minutes.

[0015] (5) After irradiation, the chitosan@polydopamine biomimetic flocculant was prepared by alternately washing with ethanol and pure water and centrifuging, and freeze-drying for 2 days, and then ground into powder for later use.

[0016] Wherein: the mass ratio of chitosan to dopamine in step (2) is 1:1-1.5. When dopamine is too little, chitosan is not completely modified, the pH environment is still harsh, and the flocculation effect is not good. When dopamine is too much, the side chains are too long, competing for the active sites of chitosan that originally react with ibuprofen. At the same time, excessive self-aggregation of dopamine will make the prepared flocculant difficult to dissolve.

[0017] In step (3), the pH of the chitosan and dopamine mixed solution is adjusted to 7.5 to 8. When the pH value is too low, the reaction conditions of the Shiff base reaction cannot be met. When the pH value is too high, the chitosan molecules may be degraded and dopamine may be excessively self-polymerized.

[0018] In step (4), the content of V-50 photoinitiator is controlled at 0.1% to 0.2%. When the amount of initiator added is too little, the number of active free radicals generated is limited, the polymerization reaction rate is reduced, and the molecular structure of the chitosan@polydopamine flocculant is not perfect; when the amount of initiator added is too much, there are too many active free radicals, the polymerization reaction is violent, and dopamine is excessively self-polymerized.

[0019] In step (4), the water bath heating temperature is controlled to be 30°C to 40°C. When the temperature is too low, the viscosity of water will increase, which will increase the resistance to the movement of molecules, thereby 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 step (4) is irradiated under low-pressure ultraviolet light for 90 to 120 minutes. When the irradiation time is too short, the synthesized flocculant has a low intrinsic viscosity, the graft polymerization reaction is incomplete, and the grafting efficiency is low. When the irradiation time is too long, ultraviolet irradiation may cause the generated graft copolymer product to undergo a disproportionation reaction, resulting in a product with unstable structure or poor performance.

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

[0022] 1. The bionic flocculant prepared by the present invention is biodegradable and non-toxic and harmless, which can effectively overcome the shortcomings of organic and inorganic flocculants' residual monomers being harmful to organisms and causing secondary environmental pollution, thereby improving biological safety and environmental protection.

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

[0024] 3. By using bionic flocculants, the dosage of conventional inorganic and organic flocculants can be reduced, thereby reducing the operating costs of municipal sewage treatment plants. DETAILED DESCRIPTION

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

[0026] Embodiment 1:

[0027] (1) Prepare a chitosan solution with a concentration of 50 wt %. Add chitosan to pure water in a sealed bottle, add glacial acetic acid dropwise, and heat and stir overnight to dissolve.

[0028] (2) Prepare a dopamine solution with a concentration of 50 wt %, stir and dissolve the dopamine in another portion of pure water, and then pour the solution into the dissolved chitosan solution.

[0029] (3) Using 1 mol / L sodium hydroxide and hydrochloric acid solution, the pH of the mixed solution of chitosan and dopamine was adjusted to a weak alkaline pH of 7.5.

[0030] (4) After nitrogen was continuously introduced into the mixture for 15 min, the mixture was immediately sealed and placed in an ultrasonic cleaner for ultrasonic treatment for 5 min. After 0.1% V-50 photoinitiator was added, nitrogen was introduced again for 15 min. Subsequently, the mixture was heated in a 30° C. water bath and irradiated under a 50-W low-pressure ultraviolet light for 90 min.

[0031] (5) After irradiation, the chitosan@polydopamine flocculant was prepared by alternately washing with ethanol and pure water and centrifuging, and then freeze-drying for 2 days.

[0032] Embodiment 2:

[0033] (1) Prepare a chitosan solution with a concentration of 50 wt %. Add chitosan to pure water in a sealed bottle, add glacial acetic acid dropwise, and heat and stir overnight to dissolve.

[0034] (2) Prepare a dopamine solution with a concentration of 50 wt %, stir and dissolve the dopamine in another portion of pure water, and then pour the solution into the dissolved chitosan solution.

[0035] (3) Using 1 mol / L sodium hydroxide and hydrochloric acid solution, the pH of the mixed solution of chitosan and dopamine was adjusted to a weak alkaline pH of 7.5.

[0036] (4) After nitrogen was continuously introduced into the mixture for 15 min, the mixture was immediately sealed and placed in an ultrasonic cleaner for ultrasonic treatment for 5 min. After 0.1% V-50 photoinitiator was added, nitrogen was introduced again for 15 min. Subsequently, the mixture was heated in a 40° C. water bath and irradiated under a 50-W low-pressure ultraviolet lamp for 90 min.

[0037] (5) After irradiation, the chitosan@polydopamine flocculant was prepared by alternately washing with ethanol and pure water and centrifuging, and then freeze-drying for 2 days.

[0038] Embodiment 3:

[0039] (1) Prepare a chitosan solution with a concentration of 50 wt %. Add chitosan to pure water in a sealed bottle, add glacial acetic acid dropwise, and heat and stir overnight to dissolve.

[0040] (2) Prepare a dopamine solution with a concentration of 50 wt %, stir and dissolve the dopamine in another portion of pure water, and then pour the solution into the dissolved chitosan solution.

[0041] (3) Using 1 mol / L sodium hydroxide and hydrochloric acid solution, the pH of the mixed solution of chitosan and dopamine was adjusted to a weak alkaline pH of 8.

[0042] (4) After nitrogen was continuously introduced into the mixture for 15 min, the mixture was immediately sealed and placed in an ultrasonic cleaner for ultrasonic treatment for 5 min. After 0.1% V-50 photoinitiator was added, nitrogen was introduced again for 15 min. Subsequently, the mixture was heated in a 40° C. water bath and irradiated under a 50-W low-pressure ultraviolet lamp for 90 min.

[0043] (5) After irradiation, the chitosan@polydopamine flocculant was prepared by alternately washing with ethanol and pure water and centrifuging, and then freeze-drying for 2 days.

[0044] Embodiment 4:

[0045] (1) Prepare a chitosan solution with a concentration of 50 wt %. Add chitosan to pure water in a sealed bottle, add glacial acetic acid dropwise, and heat and stir overnight to dissolve.

[0046] (2) Prepare a dopamine solution with a concentration of 50 wt %, stir and dissolve the dopamine in another portion of pure water, and then pour the solution into the dissolved chitosan solution.

[0047] (3) Using 1 mol / L sodium hydroxide and hydrochloric acid solution, the pH of the mixed solution of chitosan and dopamine was adjusted to a weak alkaline pH of 8.

[0048] (4) After nitrogen was continuously introduced into the mixture for 15 min, the mixture was immediately sealed and placed in an ultrasonic cleaner for ultrasonic treatment for 5 min. After adding 0.1% V-50 photoinitiator, nitrogen was introduced again for 15 min. Subsequently, the mixture was heated in a 40° C. water bath and irradiated under a 50-W low-pressure ultraviolet lamp for 120 min.

[0049] (5) After irradiation, the chitosan@polydopamine flocculant was prepared by alternately washing with ethanol and pure water and centrifuging, and then freeze-drying for 2 days.

[0050] Embodiment 5:

[0051] (1) Prepare a chitosan solution with a concentration of 50 wt %. Add chitosan to pure water in a sealed bottle, add glacial acetic acid dropwise, and heat and stir overnight to dissolve.

[0052] (2) Prepare a dopamine solution with a concentration of 50 wt %, stir and dissolve the dopamine in another portion of pure water, and then pour the solution into the dissolved chitosan solution.

[0053] (3) Using 1 mol / L sodium hydroxide and hydrochloric acid solution, the pH of the mixed solution of chitosan and dopamine was adjusted to a weak alkaline pH of 8.

[0054] (4) After nitrogen was continuously introduced into the mixture for 15 min, the mixture was immediately sealed and placed in an ultrasonic cleaner for ultrasonic treatment for 5 min. After adding 0.1% V-50 photoinitiator, nitrogen was introduced again for 15 min. Subsequently, the mixture was heated in a 40° C. water bath and irradiated under a 50-W low-pressure ultraviolet lamp for 120 min.

[0055] (5) After irradiation, the chitosan@polydopamine flocculant was prepared by alternately washing with ethanol and pure water and centrifuging, and then freeze-drying for 2 days.

[0056] Embodiment 6:

[0057] (1) Prepare a chitosan solution with a concentration of 50 wt %. Add chitosan to pure water in a sealed bottle, add glacial acetic acid dropwise, and heat and stir overnight to dissolve.

[0058] (2) Prepare a dopamine solution with a concentration of 50 wt %, stir and dissolve the dopamine in another portion of pure water, and then pour the solution into the dissolved chitosan solution.

[0059] (3) Using 1 mol / L sodium hydroxide and hydrochloric acid solution, the pH of the mixed solution of chitosan and dopamine was adjusted to a weak alkaline pH of 8.

[0060] (4) After nitrogen was continuously introduced into the mixture for 15 min, the mixture was immediately sealed and placed in an ultrasonic cleaner for ultrasonic treatment for 5 min. After adding 0.2% V-50 photoinitiator, nitrogen was introduced again for 15 min. Subsequently, the mixture was heated in a 40° C. water bath and irradiated under a 50-W low-pressure ultraviolet lamp for 120 min.

[0061] (5) After irradiation, the chitosan@polydopamine flocculant was prepared by alternately washing with ethanol and pure water and centrifuging, and then freeze-drying for 2 days.

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

[0063] Table 1 Related properties of bionic flocculants

[0064] product Removal rate of wastewater containing ibuprofen (%) 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 bionic flocculant product prepared by the present invention has excellent and stable performance, not only enhances the removal effect of ibuprofen, but also has the characteristics of being environmentally friendly and non-toxic, and has little impact on aquatic organisms and the ecological environment. This shows that this is a feasible and effective method for preparing a bionic flocculant.

[0066] Finally, it should be noted that the above embodiments of the present invention are only examples for illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes and modifications can be made based on the above description. It is impossible to list all implementation methods here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for preparing a bionic flocculant for treating benzene ring drug wastewater, characterized in that: A chitosan solution with a concentration of 40 wt% to 50 wt% is prepared, chitosan is added to pure water and placed in a sealed bottle, glacial acetic acid is added dropwise, and heated and stirred overnight to dissolve; a dopamine solution with a concentration of 50 wt% to 60 wt% is prepared, dopamine is stirred and dissolved in another portion of pure water, and then poured into the dissolved chitosan solution; The pH value of the chitosan and dopamine mixed solution is adjusted to a weak alkalinity of 7.5 to 8 using 1 mol / L sodium hydroxide and hydrochloric acid solutions; nitrogen is continuously introduced into the mixed solution for 15 minutes and then the mixture is immediately sealed and ultrasonically treated for 5 minutes in an ultrasonic cleaning machine; 0.1% to 0.2% V-50 photoinitiator is added and nitrogen is introduced again for 15 minutes, and then the mixture is heated in a water bath at 30°C to 40°C and irradiated under a 50-watt low-pressure ultraviolet light for 90 minutes to 120 minutes; after the irradiation, ethanol and pure water are used for alternate cleaning and centrifugation, and the mixture is freeze-dried for 2 days to prepare a chitosan@polydopamine bionic flocculant, which is ground into powder for later use.

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