A method for treating organophosphate hazardous waste

Abstract

The present invention provides a method for treating organophosphate hazardous waste, the method comprising the steps of: mixing organophosphate and cerium dioxide in a certain proportion in a stainless steel high-pressure stirred reactor; setting the stirring speed of the reactor to 500 rpm, a reaction temperature of 100-260°C, and a reaction time of 1-5h; after the reaction is completed, the reactor is cooled to room temperature, and the phosphorus content in the solid product, the chemical oxygen demand of the liquid product, and the total hydrocarbon and methane content in the gaseous product are respectively detected to evaluate the degradation, mineralization and phosphorus immobilization efficiency of the organophosphate. The present invention draws on the reaction principle of chemical looping combustion, utilizes the characteristics of cerium dioxide releasing oxygen and generating active oxygen species at high temperatures, realizes efficient degradation, high mineralization and phosphorus immobilization of organophosphate hazardous waste, and avoids the environmental pollution risk brought by the large-scale release of secondary products.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic hazardous waste treatment, and in particular relates to a method for treating organic phosphate hazardous waste. Background Art

[0002] Organophosphates are a class of synthetic phosphoric acid derivatives containing organic groups, with phosphorus as the central atom and a phosphate group as the backbone. Depending on the substituents, they can be divided into three categories: alkyl phosphates, aromatic phosphates, and halogenated phosphates. With the widespread use of organophosphates in industries such as pharmaceuticals, agriculture, nuclear energy, power generation, and chemical production, their environmental hazards are becoming increasingly apparent. Therefore, the safe disposal of hazardous organophosphate wastes is urgent.

[0003] Existing methods for treating hazardous waste from organophosphates include direct incineration, wet oxidation, alkaline hydrolysis, absorption, solidification, and biodegradation. However, these methods all have certain shortcomings, such as low degradation efficiency, long degradation time, the need to treat the generated tail gas and secondary waste, or lack of ideal economic efficiency. In addition, most treatment methods do not consider the reasonable and safe disposal of the phosphorus element in organophosphates.

[0004] Based on this, it is very important to develop efficient new disposal technologies to achieve efficient degradation, high mineralization and simultaneous immobilization of phosphorus elements of organophosphates for the harmless disposal of organophosphate hazardous wastes. Summary of the Invention

[0005] In view of the above-mentioned shortcomings, the object of the present invention is to propose a method for treating hazardous waste of organophosphates, which can achieve a high degradation rate of organophosphates (~100%), a high mineralization rate (>90%), excellent phosphorus immobilization efficiency (~100%), and low non-methane total hydrocarbon emissions.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for treating organophosphate hazardous waste, comprising:

[0008] (1) adding an organophosphate and cerium dioxide to a stainless steel high-pressure stirred reactor, sealing the reactor, setting the stirring speed, reaction temperature, and time, and starting the reaction;

[0009] (2) After the reaction is completed, the reactor is cooled to room temperature, and the gas phase products formed after the reaction are collected, the composition of the gas phase products is detected, and the total hydrocarbons and methane are quantitatively analyzed to calculate the total non-methane hydrocarbon content;

[0010] (3) After the reaction is completed, the reactor is cooled to room temperature, the solid phase product is washed, the liquid phase product deposited in the solid phase product after the reaction is collected, the chemical oxygen demand of the liquid phase product is detected, and the mineralization rate of the organophosphate degradation is calculated;

[0011] (4) After the reaction is completed, the reactor is cooled to room temperature, the solid phase product is collected, and after digestion, the phosphorus content in the digestion solution is detected, and then the phosphorus immobilization efficiency after the degradation of the organophosphate is calculated.

[0012] Furthermore, the organic phosphate in step (1) includes: tributyl phosphate, tricresyl phosphate, and trichloroethyl phosphate.

[0013] Furthermore, in step (1), the ratio of the organic phosphate to cerium dioxide is 1 mL: (4.8-24.8) g.

[0014] Furthermore, the ratio of the organic phosphate to cerium dioxide is 1 mL:19.8 g.

[0015] Furthermore, in step (1), the stirring speed is 500 rpm, the reaction temperature is 100-260° C., and the reaction time is 1-5 h.

[0016] Furthermore, the reaction temperature is 180° C. and the reaction time is 3 h.

[0017] Furthermore, the non-methane total hydrocarbon content in the gaseous product formed after the reaction in step (2) meets the requirements of the emission limits of air pollutants from new pollution sources in the "GB16297-1996 Integrated Emission Standard of Air Pollutants".

[0018] Furthermore, the mineralization rate of the organic phosphate after degradation in step (3) is not less than 90%.

[0019] Furthermore, the phosphorus immobilization efficiency after the degradation of the organic phosphate in step (4) is not less than 90%.

[0020] The beneficial effects of the present invention are:

[0021] The method for treating organophosphate hazardous waste described in the present invention is based on the principle of chemical chaining combustion. The oxygen in cerium dioxide is released at high temperature to form active oxygen species. Under the combined action of flameless combustion and active oxygen species, the organophosphate is efficiently decomposed. The carbon chains in the organophosphate are further oxidized and decomposed and ultimately mineralized into small molecules such as carbon dioxide and water. At the same time, the phosphorus element in the organophosphate is released and combines with the cerium element on the surface of cerium dioxide to form an insoluble solid phase product including cerium phosphate, thereby achieving the purpose of phosphorus immobilization.

[0022] After treatment with the technology described in the present invention, the degradation rates of tributyl phosphate, tricresyl phosphate and trichloroethyl phosphate are close to 100%, the mineralization rate is greater than 90%, and the phosphorus immobilization efficiency is close to 100%. At the same time, the non-methane total hydrocarbon content in the gas phase product meets the emission limit of new pollution sources of air pollutants in the "GB 16297-1996 Integrated Emission Standard of Air Pollutants" of less than 120mg / m -3 requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 3 is a comparative schematic diagram of the phosphorus immobilization efficiency after the ball-milled ceria catalyzed degradation of tributyl phosphate under different reaction temperature conditions in Example 2 of the present invention.

[0024] Figure 2 3 is a comparative schematic diagram of the phosphorus immobilization efficiency after the ball-milled ceria catalyzed degradation of tributyl phosphate under different reaction time conditions in Example 3 of the present invention.

[0025] Figure 3 3 is a comparative schematic diagram of the phosphorus immobilization efficiency after the ball-milled ceria catalyzed degradation of tributyl phosphate under different catalyst dosage conditions in Example 4 of the present invention.

[0026] Figure 4 These are the transmission electron microscope images and surface element distribution images of the solid phase product after ball-milled ceria catalyzed degradation of tributyl phosphate in Example 5 of the present invention.

[0027] Figure 5 1 is a comparative diagram of the phosphorus immobilization efficiency, chemical oxygen demand removal rate, and total hydrocarbon / methane / non-methane total hydrocarbon content in the gas phase products of the catalytic degradation of tributyl phosphate, tricresyl phosphate, and trichloroethyl phosphate by ball-milled ceria in Example 6 of the present invention. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the embodiments and accompanying drawings. However, it should be understood that the embodiments and accompanying drawings are merely exemplary descriptions of the present invention and do not constitute any limitation on the scope of protection of the present invention. All reasonable variations and combinations within the scope of the inventive concept of the present invention fall within the scope of protection of the present invention.

[0029] Example 1:

[0030] 19.8g of raw ceria was added to a stainless steel high-pressure stirred reactor, and 1mL of tributyl phosphate was dispersed dropwise into the reactor. After the reactor was assembled, the reaction temperature was set at 220°C, the stirring speed was 500 rpm, and the reaction time was 3 hours. After the reaction was completed and the reactor was naturally cooled to room temperature, the solid product was washed three times with n-hexane. The collected solid product was dried in a 60°C oven. A certain amount of the solid product was digested with strong acid, and the phosphorus content in the digestion solution was determined using the "GB 11893-89 Water Quality - Determination of Total Phosphorus - Ammonium Molybdate Spectrophotometric Method" according to the method described in "GB 11893-89 Water Quality - Determination of Total Phosphorus - Ammonium Molybdate Spectrophotometric Method." The calculated phosphorus immobilization efficiency of the tributyl phosphate after degradation by ceria was 95.6%.

[0031] Similarly, the above reaction was carried out using ball-milled ceria, and it was calculated that the phosphorus immobilization efficiency of tributyl phosphate after degradation by ball-milled ceria was transferred to the solid phase product and reached more than 99.9%.

[0032] Example 2:

[0033] Add 19.8g of ball-milled cerium dioxide into a stainless steel high-pressure stirred reactor, and then disperse and drop 1mL of tributyl phosphate into it. After installing the reactor, set the stirring speed to 500 rpm, the reaction time to 3h, and the reaction temperature to 100, 140, 180, 220 or 260℃. After the reaction is completed and the reactor is naturally cooled to room temperature, wash the solid product 3 times with n-hexane. After the collected solid product is placed in a 60℃ oven for drying, a certain amount of solid product is taken and digested with strong acid, and the phosphorus content in the digestion solution is determined using "GB 11893-89 Determination of total phosphorus in water quality - Ammonium molybdate spectrophotometry". Figure 1 As shown in the figure, as the reaction temperature increases, the phosphorus immobilization efficiency of tributyl phosphate after degradation by ball-milled ceria increases from 62.3% (100°C) to nearly 100% (180-260°C). Therefore, a reaction temperature of 180°C was selected as the optimal treatment temperature.

[0034] Example 3:

[0035] Add 19.8g of ball-milled cerium dioxide into a stainless steel high-pressure stirred reactor, and then disperse and drop 1mL of tributyl phosphate into it. After installing the reactor, set the stirring speed to 500 rpm, the reaction temperature to 180°C, and the reaction time to 1, 2, 3, 4 or 5h. After the reaction is completed and the reactor is naturally cooled to room temperature, wash the solid product 3 times with n-hexane. After the collected solid product is placed in a 60°C oven for drying, a certain amount of solid product is taken and digested with strong acid, and the phosphorus content in the digestion solution is determined using "GB 11893-89 Determination of total phosphorus in water quality - Ammonium molybdate spectrophotometry". Figure 2As shown in the figure, with the extension of reaction time, the phosphorus immobilization efficiency of tributyl phosphate after degradation by ball-milled ceria increased from 93.2% (1 h) to nearly 100% (3-5 h). Therefore, a reaction time of 3 h was selected as the optimal treatment time.

[0036] Example 4:

[0037] Add 4.8, 9.8, 14.8, 19.8 or 24.8 g of ball-milled cerium dioxide into a stainless steel high-pressure stirred reactor, and then disperse and drop 1 mL of tributyl phosphate into it. After installing the reactor, set the stirring speed to 500 rpm, the reaction temperature to 180°C, and the reaction time to 3 hours. After the reaction is completed and the reactor is naturally cooled to room temperature, wash the solid product 3 times with n-hexane. After the collected solid product is placed in a 60°C oven for drying, a certain amount of solid product is taken and digested with strong acid, and the phosphorus content in the digestion solution is determined using "GB 11893-89 Determination of total phosphorus in water quality - Ammonium molybdate spectrophotometry". Figure 3 As shown in the figure, with the increase of ball-milled ceria dosage, the phosphorus immobilization efficiency of tributyl phosphate after degradation by ball-milled ceria increased from 74.8% (4.8g) to nearly 100% (19.8-24.8g). Therefore, 19.8g CeO2 per mL TBP was selected as the optimal catalyst dosage.

[0038] Example 5:

[0039] Add 19.8g ball-milled cerium dioxide into a stainless steel high-pressure stirred reactor, and then disperse and drop 1mL tributyl phosphate into it. After installing the reactor, set the stirring speed to 500 rpm, the reaction temperature to 180°C, and the reaction time to 3h. After the reaction is completed and the reactor is naturally cooled to room temperature, wash the solid product 3 times with n-hexane. After the collected solid product is placed in a 60°C oven for drying, the morphology and surface element distribution of the solid product are observed using a transmission electron microscope. Figure 4 As shown, the solid product after the reaction is in the form of nanoparticle accumulation. Signals of cerium, oxygen and phosphorus elements are detected on the surface of the solid product, and the elements are distributed relatively evenly, indicating that after the degradation of tributyl phosphate, the phosphorus element is transferred and fixed in the solid product.

[0040] Example 6:

[0041] 19.8g of ball-milled cerium dioxide was added to a stainless steel high-pressure stirred reactor. 1mL of tributyl phosphate, tricresyl phosphate, or trichloroethyl phosphate was then dispersed dropwise into the reactor. After the reactor was assembled, the stirring speed was set to 500 rpm, the reaction temperature to 180°C, and the reaction time to 3 hours. After the reaction was completed and the reactor cooled naturally to room temperature, the solid product was washed three times with n-hexane and dried in a 60°C oven. A certain amount of the solid product was digested with strong acid, and the phosphorus content in the digestion solution was determined using the "GB 11893-89 Water Quality—Determination of Total Phosphorus—Ammonium Molybdate Spectrophotometric Method" according to the standard. The solid phase was washed with n-hexane, the washing solution was collected, and the n-hexane was completely evaporated. The remaining liquid phase was digested, and the chemical oxygen demand (COD) of the digestion solution was determined according to the standard "HJ828-2017 Water Quality—Determination of Chemical Oxygen Demand—Dichromate Method." Collect the gas phase products and use the "HJ 38-2017 Gas Chromatography Method for Determination of Total Hydrocarbons, Methane and Non-methane Total Hydrocarbons in Waste Gas from Stationary Pollution Sources" to detect the concentration of non-methane total hydrocarbons in the gas phase products. Figure 5 As shown in the results, after ball-milling ceria degradation of tributyl phosphate (TBP), tricresyl phosphate (TCP), and trichloroethyl phosphate (TCEP), the phosphorus immobilization efficiencies of phosphorus transfer to the solid phase products reached 99.9%, 97.9%, and 97.6%, respectively. The mineralization rates of the liquid phase products produced by ball-milling ceria degradation of TBP, TCP, and TCEP reached 98.3%, 98.5%, and 95.8%, respectively. The concentrations of non-methane hydrocarbons (NMHC) in the gas phase products produced by ball-milling ceria degradation of TBP, TCP, and TCEP were 0.58, 37.79, and 27.52 mg m-3, respectively. -3 , which is lower than the emission limit of air pollutants from new pollution sources in GB 16297-1996 Integrated Emission Standard of Air Pollutants <120mg m -3 The results show that the method for treating hazardous waste of organophosphates proposed in the present invention has the advantages of high efficiency, high mineralization and high phosphorus immobilization efficiency.

Claims

1. A method for treating organophosphate hazardous waste, comprising: (1) adding an organic phosphate and cerium dioxide into a stainless steel high-pressure stirred reactor, mixing, and then sealing for reaction; (2) After the reaction is completed, the reaction is cooled to room temperature, the gas phase products formed after the reaction are collected, the composition of the gas phase products is detected, and the total hydrocarbons and methane are quantitatively analyzed to calculate the total non-methane hydrocarbon content; (3) washing the solid phase product in the reactor, collecting the liquid phase product deposited in the solid phase product after the reaction, detecting the chemical oxygen demand of the liquid phase product, and then calculating the mineralization rate of the organophosphate degradation; (4) The washed solid phase product is digested, and the phosphorus content in the digestion solution is detected, and then the immobilization efficiency of phosphorus after degradation of the organophosphate is calculated.

2. The method according to claim 1, wherein: The organic phosphate in step (1) is selected from the group consisting of tributyl phosphate, tricresyl phosphate, and trichloroethyl phosphate.

3. The method according to claim 1, wherein: The ratio of the organic phosphate to cerium dioxide in step (1) is 1 mL: (4.8-24.8) g.

4. The method according to claim 3, wherein: The ratio of the organic phosphate to cerium dioxide is 1 mL:19.8 g.

5. The method according to claim 1, wherein: The cerium dioxide in step (1) is untreated original cerium dioxide or cerium dioxide treated by ball milling.

6. The method according to claim 5, wherein: The ball-milled cerium dioxide is prepared by the following method: Add 5 times the amount of water to cerium dioxide and ball mill at 600 rpm for 2 h.

7. The method according to claim 1, wherein: The sealing reaction conditions after mixing in step (1) are: stirring speed of 500 rpm, reaction temperature of 100-260° C., and reaction time of 1-5 h.

8. The method according to claim 7, wherein: The reaction temperature is 180° C. and the reaction time is 3 h.

9. The method according to claim 1, wherein: The mineralization rate of the organic phosphate after degradation in step (3) is not less than 90%.

10. The method of claim 1, wherein: After the organic phosphate is degraded in step (4), the phosphorus immobilization efficiency is not less than 90%.

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