Glyphosate production process with zero discharge of wastewater

Abstract

The application discloses a glyphosate production process of zero-emission wastewater and belongs to the technical field of pesticide wastewater treatment. Hydrochloric acid and sodium hydroxide solution are added dropwise into sodium silicate solution, pH is adjusted, and stirring and activation are carried out to obtain polysilicic acid solution. Iron chloride is added into the polysilicic acid solution, stirring and dissolution and activation are carried out to obtain polysilicic acid-iron chloride solution. Water is added into starch to prepare starch paste, glycerol, polyethylene glycol and sodium hexametaphosphate are added, stirring is uniformly carried out, pH is adjusted, heating and magnetic stirring reaction is carried out, and a uniform paste solution, namely, composite modified starch solution, is obtained. Water is added into the obtained composite modified starch solution, water bath heating is carried out, solution pH is adjusted, the obtained polysilicic acid-iron chloride solution is added for reaction, and aging is carried out after cooling to room temperature, so that a composite flocculant is prepared. The obtained composite flocculant is added into glyphosate wastewater, stirring and reaction are carried out, then pH is adjusted, and flocculent precipitation is separated out through stirring.

Description

Technical Field

[0001] This invention belongs to the field of pesticide wastewater treatment technology, specifically relating to a glyphosate production process with zero wastewater discharge. Background Technology

[0002] Glyphosate is an organophosphorus systemic broad-spectrum non-selective herbicide. Currently, the main industrial-scale production processes for glyphosate are the IDA process and the glycine dialkyl phosphite method. However, the circulating water system in the glycine-based glyphosate process has a significant impact on the glyphosate yield, presenting the following problems: high circulating water temperature during glyphosate crystallization leads to poor cooling; the circulating water itself has a high concentration ratio, contains many impurities, and is prone to scaling, resulting in unstable water quality and poor cooling for subsequent methanol and chloromethane recovery, thus limiting production capacity; and it causes severe corrosion to system pipelines. Therefore, the circulating water has the most direct impact on continuous glyphosate production. Utilizing rapidly developing new technologies and processes, further analysis and exploration of glyphosate production equipment are needed to improve cooling efficiency and reduce consumption.

[0003] The development of glyphosate production in my country began in the 1980s. With advancements in glyphosate processing technology, the IDA (Inductively Coupled Acid) method, representing an advanced technological route, has been gradually promoted. The IDA route—diethanolamine process—in this process, diethanolamine and caustic soda are directly synthesized into iminodiacetonitrile (IDAN). This process boasts high conversion rates, good product quality, a relatively environmentally friendly operating environment, and minimal environmental impact. However, glyphosate wastewater still contains pollutants such as adsorbable organic halogens (AOX), toluene, formaldehyde, and ammonia nitrogen. Summary of the Invention

[0004] The purpose of this invention is to provide a glyphosate production process with zero wastewater discharge, which solves the problem of multiple pollutants in glyphosate wastewater as mentioned in the background art. The treated glyphosate wastewater can adsorb pollutants such as organic halogens (AOX), toluene, formaldehyde, and ammonia nitrogen, and the discharge value meets the national pesticide wastewater discharge standards.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A glyphosate production process with zero wastewater discharge includes the following process steps:

[0007] (1) Preparation of polysilicic acid-ferric chloride solution:

[0008] Add hydrochloric acid and sodium hydroxide solution dropwise to 40-50 parts by weight of 0.2 mol / L sodium silicate solution, adjust the pH to 2-3, stir and activate for 1-2 hours to obtain polysilicic acid solution;

[0009] Add 15-25 parts by weight of ferric chloride to the obtained polysilicic acid solution, stir to dissolve, and activate to obtain a polysilicic acid-ferric chloride solution;

[0010] (2) Composite modification of starch:

[0011] Add water to 20-30 parts by weight of starch in a 1:5 ratio to make a starch paste. Then add 1-2 parts by weight of glycerol, 2-3 parts by weight of polyethylene glycol, and 1-3 parts by weight of sodium hexametaphosphate. Stir well, adjust the pH to 9, heat and stir magnetically, and react at 90-95℃ for 0.5h to obtain a uniform gelatinized solution, i.e., a composite modified starch solution.

[0012] (3) Preparation of composite flocculant:

[0013] Add water at a ratio of 1:10 to the composite modified starch solution obtained in step (2), heat in a water bath at 40-50℃, adjust the pH of the solution to 2, add the polysilicic acid-ferric chloride solution obtained in step (1) and react for 2-3 hours. After cooling to room temperature, mature to obtain the composite flocculant.

[0014] (4) Treatment of glyphosate wastewater:

[0015] Add the composite flocculant obtained in step (3) to the glyphosate wastewater, stir and react at 35-45℃ for 1-2 hours, then adjust the pH to 7-9 and stir to precipitate flocculent precipitate.

[0016] Furthermore, in steps (1), (2), (3), and (4) above, the pH is adjusted using 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide solution.

[0017] Furthermore, in step (4) above, the amount of composite flocculant added is 3%-5% of the mass of glyphosate wastewater.

[0018] The beneficial effects of this invention are:

[0019] (1) Polysilicic acid-ferric chloride solution was prepared using sodium silicate and ferric chloride as raw materials. Polysilicic acid and ferric ions complexed to form a polymer. Polysilicic acid-ferric chloride exhibited an irregular structure with wrinkles on its surface and dense clusters containing many pores, which increased the specific surface area and formed more binding sites, thereby enhancing the adsorption capacity.

[0020] (2) This invention improves the adsorption capacity of starch by using glycerol, sodium hexametaphosphate, and polyethylene glycol to modify starch:

[0021] Glycerol is a polyol that can form hydrogen bonds with starch molecules, increasing the hydrophilicity and swelling properties of starch. This helps starch granules absorb more water and organic molecules, thereby improving their adsorption capacity for organic halogens such as AOX and methanol.

[0022] Sodium hexametaphosphate is a polyphosphate that can form stable complexes with starch molecules, altering the starch structure and improving its solubility and dispersibility. This modification enhances the adsorption of small organic molecules such as formaldehyde and chloromethane by starch because the modified starch has better water solubility and the ability to form complexes with organic molecules.

[0023] Polyethylene glycol (PEG) is a synthetic polymer with excellent water solubility and flexibility. It can form physical or chemical complexes with starch molecules, altering the surface properties of starch and enhancing its adsorption capacity for organic molecules. The introduction of PEG enhances the adsorption of larger organic molecules such as triethylamine by starch.

[0024] (3) Preparation of composite flocculant: Ferric chloride and starch are not simply mixed, but undergo a complexation reaction to enhance the adsorption bridging effect. The synthesized flocculant contains Fe-O-C functional groups, which enhance the flocculation effect. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] A glyphosate production process with zero wastewater discharge includes the following process steps:

[0028] (1) Preparation of polysilicic acid-ferric chloride solution:

[0029] Hydrochloric acid and sodium hydroxide solution were added dropwise to 40 parts by weight of 0.2 mol / L sodium silicate solution to adjust the pH to 2. The solution was stirred and activated for 1 h to obtain polysilicic acid solution.

[0030] Add 15 parts by weight of ferric chloride to the obtained polysilicic acid solution, stir to dissolve, and activate to obtain a polysilicic acid-ferric chloride solution;

[0031] (2) Composite modification of starch:

[0032] Add water to 20 parts by weight of starch in a 1:5 ratio to make a starch paste. Then add 1 part by weight of glycerol, 2 parts by weight of polyethylene glycol, and 1 part by weight of sodium hexametaphosphate. Stir well, adjust the pH to 9, heat and stir magnetically, and react at 90°C for 0.5 h to obtain a uniform gelatinized solution, i.e., a composite modified starch solution.

[0033] (3) Preparation of composite flocculant:

[0034] Add water at a ratio of 1:10 to the composite modified starch solution obtained in step (2), heat in a 40°C water bath, adjust the pH of the solution to 2, add the polysilicic acid-ferric chloride solution obtained in step (1) and react for 2 hours. After cooling to room temperature, mature to obtain the composite flocculant.

[0035] (4) Treatment of glyphosate wastewater:

[0036] Add the composite flocculant obtained in step (3) to the glyphosate wastewater, stir and react at 35°C for 1 hour, then adjust the pH to 7 and stir to precipitate flocculent precipitate.

[0037] In the above steps, the pH is adjusted using 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide solution;

[0038] In the above steps, the amount of composite flocculant added is 3% of the mass of glyphosate wastewater.

[0039] Example 2

[0040] A glyphosate production process with zero wastewater discharge includes the following process steps:

[0041] (1) Preparation of polysilicic acid-ferric chloride solution:

[0042] Hydrochloric acid and sodium hydroxide solution were added dropwise to 45 parts by weight of 0.2 mol / L sodium silicate solution to adjust the pH to 3. The solution was stirred and activated for 1 h to obtain polysilicic acid solution.

[0043] Add 20 parts by weight of ferric chloride to the obtained polysilicic acid solution, stir to dissolve, and activate to obtain a polysilicic acid-ferric chloride solution;

[0044] (2) Composite modification of starch:

[0045] Add water to 25 parts by weight of starch in a 1:5 ratio to make a starch paste. Then add 1 part by weight of glycerol, 2 parts by weight of polyethylene glycol, and 3 parts by weight of sodium hexametaphosphate. Stir well, adjust the pH to 9, heat and stir magnetically, and react at 95°C for 0.5 hours to obtain a uniform gelatinized solution, i.e., a composite modified starch solution.

[0046] (3) Preparation of composite flocculant:

[0047] Add water at a ratio of 1:10 to the composite modified starch solution obtained in step (2), heat in a water bath at 45°C, adjust the pH of the solution to 2, add the polysilicic acid-ferric chloride solution obtained in step (1) and react for 2 hours. After cooling to room temperature, mature to obtain the composite flocculant.

[0048] (4) Treatment of glyphosate wastewater:

[0049] Add the composite flocculant obtained in step (3) to the glyphosate wastewater, stir and react at 40°C for 1 hour, then adjust the pH to 8 and stir to precipitate flocculent precipitate.

[0050] In the above steps, the pH is adjusted using 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide solution;

[0051] In the above steps, the amount of composite flocculant added is 4% of the mass of glyphosate wastewater.

[0052] Example 3

[0053] A glyphosate production process with zero wastewater discharge includes the following process steps:

[0054] (1) Preparation of polysilicic acid-ferric chloride solution:

[0055] Hydrochloric acid and sodium hydroxide solution were added dropwise to 50 parts by weight of 0.2 mol / L sodium silicate solution to adjust the pH to 3. The solution was stirred and activated for 2 hours to obtain polysilicic acid solution.

[0056] Add 25 parts by weight of ferric chloride to the obtained polysilicic acid solution, stir to dissolve, and activate to obtain a polysilicic acid-ferric chloride solution;

[0057] (2) Composite modification of starch:

[0058] Add water to 30 parts by weight of starch in a 1:5 ratio to make a starch paste. Then add 2 parts by weight of glycerol, 3 parts by weight of polyethylene glycol, and 3 parts by weight of sodium hexametaphosphate. Stir well, adjust the pH to 9, heat and stir magnetically, and react at 95°C for 0.5 hours to obtain a uniform gelatinized solution, i.e., a composite modified starch solution.

[0059] (3) Preparation of composite flocculant:

[0060] Add water at a ratio of 1:10 to the composite modified starch solution obtained in step (2), heat in a 50°C water bath, adjust the pH of the solution to 2, add the polysilicic acid-ferric chloride solution obtained in step (1) and react for 3 hours. After cooling to room temperature, mature to obtain the composite flocculant.

[0061] (4) Treatment of glyphosate wastewater:

[0062] Add the composite flocculant obtained in step (3) to the glyphosate wastewater, stir and react at 45°C for 2 hours, then adjust the pH to 9 and stir to precipitate flocculent precipitate.

[0063] In the above steps, the pH is adjusted using 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide solution;

[0064] The amount of composite flocculant added in the above steps is 5% of the mass of glyphosate wastewater.

[0065] Comparative Example 1

[0066] Compared to Example 3, no sodium silicate solution was added, but all other steps were the same.

[0067] Comparative Example 2

[0068] Compared to Example 3, no sodium silicate solution and ferric chloride were added, but all other steps were the same.

[0069] Comparative Example 3

[0070] Compared to Example 3, no glycerol, polyethylene glycol, or sodium hexametaphosphate were added, but all other steps were the same.

[0071] Comparative Example 4

[0072] Compared to Example 3, no starch, glycerol, polyethylene glycol, or sodium hexametaphosphate were added, but all other steps were the same.

[0073] The glyphosate wastewater treated in Examples 1-3 and Comparative Examples 1-4 was tested according to the methods in the "Second Draft for Comments on the Discharge Standard of Water Pollutants from Pesticide Industry" and the "Second Draft for Comments on the Discharge Standard of Water Pollutants from Organophosphorus Pesticide Industry". The discharge values ​​(unit: mg / L) of various water pollutants are shown in Table 1.

[0074] Table 1

[0075]

[0076] As can be seen from Table 1, the discharge values ​​of various pollutants in the glyphosate wastewater treated according to the methods described in Examples 1-3 of this invention meet the standard requirements;

[0077] Compared with Example 3, Comparative Example 1 did not add sodium silicate solution, that is, it did not use sodium silicate to modify ferric chloride. The content of various pollutants in the glyphosate wastewater treated increased, just exceeding the water pollutant discharge limits specified in the above standards.

[0078] Compared with Example 3, Comparative Example 2 did not add sodium silicate solution and ferric chloride, and the content of various pollutants in the glyphosate wastewater treated was further increased, greatly exceeding the water pollutant discharge limits specified in the above standards.

[0079] Compared with Example 3, Comparative Example 3 did not add glycerol, polyethylene glycol, or sodium hexametaphosphate, that is, it did not use glycerol, polyethylene glycol, or sodium hexametaphosphate to modify starch. As a result, the content of various pollutants in the glyphosate wastewater treated increased, just exceeding the water pollutant discharge limits specified in the above standards.

[0080] Compared with Example 3, Comparative Example 4 did not add starch, glycerin, polyethylene glycol, or sodium hexametaphosphate. The content of each pollutant in the glyphosate wastewater treated was further increased, greatly exceeding the water pollutant discharge limits specified in the above standards.

[0081] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0082] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A zero discharge wastewater glyphosate production process characterized in that, The process comprises the following steps: (1) Preparation of composite flocculant: Add water to 40-60 parts by weight of the composite modified starch solution at a ratio of 1:10, heat in a 40-50°C water bath, adjust the pH of the solution to 2, add 50-70 parts by weight of the polysilicic acid-ferric chloride solution and react for 2-3 hours, cool to room temperature and mature to obtain the composite flocculant; (2) Treatment of glyphosate wastewater: Add the composite flocculant obtained in step (1) to the glyphosate wastewater, stir and react at 35-45°C for 1-2 hours, then adjust the pH to 7-9 and stir to precipitate the flocculent; The preparation method of the composite modified starch comprises the following steps: Add water to 20-30 parts by weight of starch at a ratio of 1:5 to prepare a starch paste, then add 1-2 parts by weight of glycerol, 2-3 parts by weight of polyethylene glycol and 1-3 parts by weight of sodium hexametaphosphate, stir until uniform, adjust the pH to 9, heat and stir magnetically, react at 90-95°C for 0.5 hours to obtain a uniform paste solution, which is the composite modified starch solution.

2. A zero discharge wastewater glyphosate production process according to claim 1, characterized in that, Preparation of polysilicic acid-ferric chloride solution: Add 15-25 parts by weight of ferric chloride to the polysilicic acid solution, stir to dissolve and activate to obtain the polysilicic acid-ferric chloride solution.

3. A zero discharge wastewater glyphosate production process according to claim 2, characterized in that, Preparation of polysilicic acid solution: Add hydrochloric acid and sodium hydroxide solution dropwise to 40-50 parts by weight of 0.2 mol / L sodium silicate solution, adjust the pH to 2-3, stir and activate for 1-2 hours to obtain the polysilicic acid solution.

4. A zero discharge wastewater glyphosate production process as claimed in claim 1, wherein, In steps (1) and (2), 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide solution are used to adjust the pH.

5. A zero discharge wastewater glyphosate production process as claimed in claim 1, wherein, In step (2), the amount of the composite flocculant added is 3%-5% of the mass of the glyphosate wastewater.

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