Efficient metal corrosion accelerant and application

Abstract

The invention relates to an efficient metal corrosion accelerant and application, and belongs to the technical field of metal surface treatment. The O, O '-di (methyl) diethylammonium dithiophosphate can obviously accelerate the corrosion rate of metal in an acid environment and effectively remove surface impurities such as oxide skin and rust. The use concentration range of the acid pickling agent is 0.04-100 mmol / L, the acid pickling agent can be prepared into an acid pickling solution with hydrochloric acid, sulfuric acid and other inorganic acids, the operation temperature is 30-50 DEG C, the treatment time is 0.1-4 h, and the acid pickling agent is suitable for Q195, Q235 and other carbon steel materials. The pickling accelerant provided by the invention has the characteristics of high efficiency, stability, simplicity and convenience in synthesis, wide applicability and the like, the pickling efficiency can be greatly improved, the treatment time is shortened, and the requirements of the metal processing industry on efficient corrosion treatment are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal surface treatment, specifically to the direction of pickling corrosion chemical preparation, and particularly relates to a high-efficiency metal corrosion accelerator and application. The compound can significantly accelerate the corrosion rate of metal in an acidic environment, is suitable for efficient pickling treatment of metals such as carbon steel, and has the characteristics of high promotion efficiency, good stability, and simple operation. BACKGROUND

[0002] Pickling is a common surface treatment process in metal processing, mainly used to remove impurities such as oxide scale, rust, and welding oxides on the metal surface to improve the cleanliness of the metal surface and the quality of subsequent coating, plating, welding, and other processes. Traditional pickling processes usually use inorganic acids (such as hydrochloric acid, sulfuric acid, etc.) as the main cleaning medium to dissolve the oxides on the metal surface through the corrosion of the acid. However, using inorganic acids alone for pickling has the problems of low processing efficiency, long pickling time, large consumption of acid, easy over-corrosion of the metal substrate or hydrogen embrittlement, and other issues, which seriously affect production efficiency and material performance.

[0003] To improve the efficiency of pickling, it is common in industry to add pickling accelerators (or pickling accelerators) to enhance the ability of the acid to remove oxides on the metal surface. Currently, the common pickling accelerators on the market mainly include halogen ion type, organic sulfide, and surfactant types. For example, sodium chloride, potassium chloride, and other halide salts can accelerate localized corrosion through the penetration of chloride ions, but their promotion effect is limited, and they can introduce chloride ion residues, exacerbating equipment corrosion and environmental burden. Certain sulfur-containing compounds (such as thiourea, mercaptobenzothiazole, etc.) have some promotion effect, but they can easily decompose and lose effectiveness at high temperatures and high acid concentrations, and can produce toxic gases, limiting their widespread application. Surfactant-type accelerators mainly improve pickling effects through wetting and penetration, but have weak corrosion promotion effect on the base metal, making it difficult to achieve efficient and rapid cleaning.

[0004] On the other hand, existing pickling accelerators mainly focus on "removing oxides" while trying to "inhibit base corrosion", which has some contradictions with the actual needs of metal pickling. Especially in some special processes (such as metal regeneration treatment, scrap recovery, and rapid rust removal before rough machining), the metal substrate needs to be rapidly and massively corroded, and traditional pickling agents cannot meet the needs of efficient corrosion. Therefore, developing a new type of pickling accelerator that can actively and controllably promote the corrosion of the metal substrate has important industrial application value.

[0005] O,O'-di(methyl)dithiophosphoric acid diethyl ammonium is an organic phosphorus ammonium salt compound, which contains active elements such as phosphorus, sulfur and nitrogen in the structure, and has good metal coordination and interfacial activity. In the prior art, such compounds are mostly used in the fields of pesticides, lubricating oil additives and the like, and no related report is found as pickling accelerators. The present application first finds that the compound shows a significant corrosion promotion effect on metals such as carbon steel in an acidic environment, can greatly improve the pickling rate and shorten the treatment time, and has good popularization prospect due to simple synthesis, high stability and good environmental adaptability.

[0006] In summary, it is of great significance to develop a new type of efficient pickling accelerator, especially a compound capable of actively promoting metal corrosion, for improving the efficiency and economy of metal pickling process. Based on the above background, the present application proposes the application of O,O'-di(methyl)dithiophosphoric acid diethyl ammonium as a pickling accelerator, which fills the gap in this technical field. SUMMARY

[0007] The present application aims to provide an efficient metal corrosion accelerator and application. The O,O'-di(methyl)dithiophosphoric acid diethyl ammonium can greatly accelerate the corrosion rate of metal, thereby effectively shortening the pickling time and improving the production efficiency.

[0008] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions: The present application provides the application of O,O'-di(methyl)dithiophosphoric acid diethyl ammonium as a pickling accelerator.

[0009] Preferably, the effective concentration of the O,O'-di(methyl)dithiophosphoric acid diethyl ammonium is 0.04-100 mmol / L.

[0010] The present application also provides a method for preparing a pickling solution, comprising the following steps: O,O'-di(methyl)dithiophosphoric acid diethyl ammonium is added to inorganic acid to obtain the pickling solution.

[0011] Preferably, the molar concentration ratio of the O,O'-di(methyl)dithiophosphoric acid diethyl ammonium to the inorganic acid is 0.04-100 mmol / L: 0.1-1 mol / L.

[0012] Preferably, the inorganic acid is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, hydrofluoric acid, nitric acid and carbonic acid.

[0013] The present application also provides a pickling method, comprising the following steps: The metal to be treated is added to the pickling solution and soaked to obtain the pickled metal; or The pickling solution is sprayed onto the surface of the metal to be treated to obtain the pickled metal.

[0014] Preferably, the temperature of the soaking or spraying is 30~50℃, the soaking or spraying time is 0.1~4h, and the metal to be treated includes low carbon steel.

[0015] More preferably, the low-carbon steel includes one of Q195, Q215, Q235, Q255 and Q275.

[0016] This invention also provides the application of O,O′-di(methyl)dithiophosphate diethylammonium in the preparation of pickling additives.

[0017] Preferably, the effective concentration of the O,O′-di(methyl)dithiophosphate diethylammonium is 0.04~100 mmol / L.

[0018] The beneficial effects of this invention compared to the prior art are as follows: This invention employs O,O′-di(methyl)dithiophosphate diethylammonium as a novel pickling accelerator, characterized by high efficiency, stable pickling promotion performance, and simple synthesis. It also has a wide range of applications and promising prospects. The most significant feature of the pickling accelerator provided by this invention is its ability to greatly accelerate the corrosion rate of metals during acidic corrosion processes. This characteristic significantly improves the efficiency of metal pickling, rapidly removing oxide scale, rust, and other impurities from metal surfaces. It is particularly suitable for production scenarios with high pickling efficiency requirements, effectively shortening pickling time and improving production progress. Compared with similar products on the market, it has a clear advantage in corrosion promotion effect, better meeting the high-efficiency processing needs of various industries in metal processing.

[0019] The O,O′-di(methyl)dithiophosphate diethylammonium is suitable for surface pickling of various metal materials, covering key processes such as metal raw material pretreatment, deep cleaning of metal products, and surface optimization of metal components. Whether it's metal sheets, pipes, profiles, or complex metal parts, O,O′-di(methyl)dithiophosphate diethylammonium can improve pickling efficiency and quality, laying a solid foundation for subsequent processing, coating, welding, and other procedures, and promoting the upgrading of the metal pickling industry towards more efficient and refined processing.

[0020] The pickling accelerator provided by this invention can act on intact metal surfaces (free from oxidation, dirt, etc.) and greatly accelerate the rate of corrosion on the metal surface in acidic solutions. The technical effect of this invention is the opposite of that of conventional pickling agents (conventional agents "inhibit substrate corrosion," while this invention "promotes substrate corrosion").

[0021] Meanwhile, the pickling accelerator provided by this invention is designed for specific scenarios (such as scenarios where the substrate does not need to be preserved and the surface of intact metal needs to be rapidly corroded), and can significantly accelerate the corrosion rate of intact metal under acidic conditions, which is significantly different from the 'corrosion inhibition' logic of conventional pickling agents. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 SEM image of a newly polished low-carbon steel sheet sample; Figure 2 SEM image of a low-carbon steel sheet sample after being etched with hydrochloric acid solution; Figure 3 SEM image of a low-carbon steel sheet sample after being etched by an acidic solution containing 0.08 mmol / L O′-di(methyl)dithiophosphate diethylammonium; Figure 4 SEM image of a low-carbon steel sheet sample after being etched by an acidic solution containing 0.2 mmol / L O′-di(methyl)dithiophosphate diethylammonium; Figure 5 SEM image of a low-carbon steel sheet sample after being etched by an acidic solution containing 0.4 mmol / L O′-di(methyl)dithiophosphate diethylammonium; Figure 6 SEM image of a low-carbon steel sheet sample after being etched by an acidic solution containing 0.8 mmol / L O′-di(methyl)dithiophosphate diethylammonium; Figure 7 EDS test results for newly polished low-carbon steel sheet samples; Figure 8 EDS test results for low-carbon steel sheet samples after hydrochloric acid corrosion; Figure 9 The results are EDS analysis of a low-carbon steel sheet sample after it has been etched with an acidic solution containing 0.08 mmol / L O′-di(methyl)dithiophosphate diethylammonium. Figure 10 The results are EDS analysis of a low-carbon steel sheet sample after it has been etched with an acidic solution containing 0.2 mmol / L O′-di(methyl)dithiophosphate diethylammonium. Figure 11 The results are EDS analysis of a low-carbon steel sheet sample after it has been etched with an acidic solution containing 0.4 mmol / L O′-di(methyl)dithiophosphate diethylammonium. Figure 12 The results are EDS analysis of a low-carbon steel sheet sample after it has been etched by an acidic solution containing 0.8 mmol / L O′-di(methyl)dithiophosphate diethylammonium. Detailed Implementation

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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 apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0028] 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.

[0029] This invention provides the application of O,O′-di(methyl)dithiophosphate diethylammonium as an acid washing accelerator.

[0030] In this invention, the O,O′-di(methyl)dithiophosphate diethylammonium belongs to the organophosphate ammonium salt class. It is an ionic compound composed of cations and anions bonded by electrostatic interactions (ionic bonds). Its overall structure can be divided into two parts: the cation diethylammonium ion ([(CH3CH2)2NH2]). +) and the anion O,O′-di(methyl)dithiophosphate ([(CH3O)2P(S)S] - Its structural formula is shown in Formula I. Formula I; The effective concentration of the O,O′-di(methyl)dithiophosphate diethylammonium is preferably 0.04~100 mmol / L, more preferably 1~80 mmol / L, even more preferably 10~60 mmol / L, even more preferably 20~40 mmol / L, and even more preferably 30 mmol / L. The O,O′-di(methyl)dithiophosphate diethylammonium is a powdered solid that is easy to accurately measure and store. It is relatively stable in transportation and storage, requires a small amount, has a single component, and can be dissolved in water in any proportion. It can withstand changes in cleaning conditions (such as temperature, acid concentration, storage time, etc.). Changes in the corrosive environment have little impact on the promoting effect of the pickling accelerator, and it has the advantage of a long continuous action time. It can be dissolved in inorganic acid to obtain an acidic solution, which can be used for pickling metals. It has the characteristics of simple and convenient operation.

[0031] The present invention also provides a method for preparing an acid washing solution, comprising the following steps: O,O′-di(methyl)dithiophosphate diethylammonium was added to an inorganic acid to obtain the pickling solution.

[0032] In this invention, the molar ratio of O,O′-di(methyl)dithiophosphate diethylammonium to the inorganic acid is preferably 0.04~100 mmol / L: 0.1~1 mol / L, more preferably 1~80 mmol / L: 0.2~0.8 mol / L, even more preferably 10~60 mmol / L: 0.4~0.6 mol / L, even more preferably 20~40 mmol / L: 0.5 mol / L, and even more preferably 30 mmol / L: 0.5 mol / L; the inorganic acid is preferably one or more of hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, hydrofluoric acid, nitric acid, and carbonic acid, more preferably one or more of hydrochloric acid, phosphoric acid, hydrofluoric acid, and carbonic acid, and even more preferably hydrochloric acid and / or sulfuric acid.

[0033] The present invention also provides a pickling method, comprising the following steps: The metal to be treated is added to the pickling solution and immersed to obtain the pickled metal; or The pickling solution is sprayed onto the surface of the metal to be treated to obtain the pickled metal.

[0034] In this invention, the soaking or spraying temperature is preferably 30~50℃, more preferably 35~45℃, and even more preferably 40℃; the soaking or spraying time is preferably 0.1~4h, more preferably 0.5~3.5h, even more preferably 1~3h, even more preferably 1.5~2.5h, and even more preferably 2h; the metal to be treated preferably includes low-carbon steel, which is carbon steel with a carbon content of less than 0.25%; the low-carbon steel is further preferably one of Q195, Q215, Q235, Q255 and Q275.

[0035] This invention also provides the application of O,O′-di(methyl)dithiophosphate diethylammonium in the preparation of pickling additives.

[0036] In this invention, the effective concentration of the O,O′-di(methyl)dithiophosphate diethylammonium is preferably 0.04~100 mmol / L, more preferably 1~80 mmol / L, even more preferably 10~60 mmol / L, even more preferably 20~40 mmol / L, and even more preferably 30 mmol / L.

[0037] In this invention, the experimental electrode adopts a three-electrode system, with a saturated calomel electrode (SCE) as the reference electrode, a platinum sheet as the auxiliary electrode, and low-carbon steel as the working electrode.

[0038] Example 1 O,O′-di(methyl)dithiophosphate diethylammonium was added to 1L of hydrochloric acid solution with a concentration of 1mol / L to prepare acid washing solutions with effective concentrations of 0.04, 0.08, 0.2, 0.4, 0.8, 2, 4 and 8 mmol / L respectively.

[0039] Example 2 O,O′-di(methyl)dithiophosphate diethylammonium was added to 1 L of hydrochloric acid solution with a concentration of 0.5 mol / L to prepare acid washing solutions with effective concentrations of 0.04, 0.08, 0.2, 0.4, and 0.8 mmol / L, respectively.

[0040] Example 3 O,O′-di(methyl)dithiophosphate diethylammonium was added to 1 L of hydrochloric acid solution with a concentration of 0.1 mol / L to prepare acid washing solutions with effective concentrations of 0.04, 0.08, 0.2, 0.4, 0.8, 4, 8, 10, 30, 80, and 100 mmol / L, respectively.

[0041] Example 4 O,O′-di(methyl)dithiophosphate diethylammonium was added to 1 L of hydrochloric acid solution with a concentration of 0.1 mol / L to prepare acid washing solutions with effective concentrations of 0.08, 0.2, 0.4, and 0.8 mmol / L, respectively.

[0042] Experimental Example 1 The corrosion performance of the pickling solution prepared in Example 1 on carbon steel Q235 at different pickling temperatures was investigated. During the testing, the weight loss test of the coated plates was conducted according to the methods described in "JB / T 7901-2023 Laboratory Uniform Corrosion Full Immersion Test Method for Metallic Materials" and "SY / T 5405-2019 Performance Test Method and Evaluation Index of Corrosion Inhibitors for Acidification"; electrochemical tests were conducted according to the methods described in "DL / T 523-2017 Application Performance Evaluation Index and Test Method of Chemical Cleaning Corrosion Inhibitors". The test results are shown in Table 1.

[0043] Table 1 Corrosion properties of pickling solutions at different pickling temperatures (corrosion acceleration rate / %)

[0044] The results showed that as the concentration of O,O′-di(methyl)dithiophosphate diethylammonium increased, the corrosion performance of the acidic solution on carbon steel gradually increased, and the acidic solution exhibited the best corrosion performance at low temperatures.

[0045] Experimental Example 2 The corrosion acceleration rate of the pickling solution prepared in Example 2 on carbon steel Q235 was investigated at a pickling temperature of 30℃. During the test, the weight loss test of the coated plates was conducted according to the methods described in "JB / T 7901-2023 Laboratory Uniform Corrosion Full Immersion Test Method for Metallic Materials" and "SY / T 5405-2019 Performance Test Method and Evaluation Index of Corrosion Inhibitors for Acidification"; electrochemical tests were conducted according to the methods described in "DL / T523-2017 Application Performance Evaluation Index and Test Method of Chemical Cleaning Corrosion Inhibitors". The test results are shown in Table 2.

[0046] Table 2 Corrosive properties of pickling solutions

[0047] The results showed that at 30℃, the pickling effect of pickling solutions containing different concentrations of O,O′-di(methyl)dithiophosphate diethylammonium varied significantly, with the 0.8 mmol / L solution exhibiting the best corrosion performance and pickling effect.

[0048] Experimental Example 3 The corrosion acceleration rate of the pickling solution prepared in Example 3 on carbon steel Q235 was investigated at a pickling temperature of 30℃. During the test, the weight loss test of the coated material was conducted according to the methods described in "JB / T 7901-2023 Laboratory Uniform Corrosion Full Immersion Test Method for Metallic Materials" and "SY / T 5405-2019 Performance Test Method and Evaluation Index of Corrosion Inhibitors for Acidification"; electrochemical tests were conducted according to the methods described in "DL / T523-2017 Application Performance Evaluation Index and Test Method of Chemical Cleaning Corrosion Inhibitors". The test results are shown in Table 3.

[0049] Table 3 Corrosive properties of pickling solutions

[0050] The results showed that when the concentration of O,O′-di(methyl)dithiophosphate diethylammonium in the pickling solution increased to a certain level, the pickling effect of the pickling solution would be significantly reduced.

[0051] Test Example 4 The corrosion acceleration rate of the pickling solution and hydrochloric acid solution (without O,O′-di(methyl)dithiophosphate diethylammonium) prepared in Example 4 on carbon steel Q235 was investigated at a pickling temperature of 30℃. During the test, the weight loss experiment of the coated steel sheets was conducted according to the methods described in "JB / T 7901-2023 Laboratory Uniform Corrosion Full Immersion Test Method for Metallic Materials" and "SY / T 5405-2019 Test Method and Evaluation Index for Performance of Corrosion Inhibitors for Acidification". The experiment lasted for 4 hours. Scanning electron microscopy (SEM) and EDS were used to test the corroded low-carbon steel sheets. A freshly polished low-carbon steel sample was used as a control. The results are as follows: Figures 1 to 12 As shown.

[0052] Depend on Figures 1 to 6 It can be seen that the surface of the freshly polished low-carbon steel sample is very smooth, with only scratches left by sandpaper polishing. Observation of the surface morphology of the low-carbon steel in hydrochloric acid solution revealed that due to the corrosive effect of hydrochloric acid, the surface of the low-carbon steel was uneven, showing obvious wavy corrosion marks, but the scratches left by sandpaper polishing were still visible. In contrast, in the hydrochloric acid solution containing diethylammonium di(methyl)dithiophosphate, the corrosion of the low-carbon steel sample by hydrochloric acid was significantly enhanced, and with the increase of the concentration of the added corrosion accelerator, the degree of corrosion of the sample intensified, and obvious deep corrosion pits appeared.

[0053] Depend on Figures 7 to 12It can be seen that, compared with the surface of a freshly polished low-carbon steel sample, the C and O content of the sample surface increased significantly after corrosion in hydrochloric acid solution. In hydrochloric acid solution with added O,O′-di(methyl)dithiophosphate diethylammonium, the C and O content of the sample surface increased further after the low-carbon steel sample was eroded by hydrochloric acid, indicating a significant acceleration of corrosion; and with the increase of O,O′-di(methyl)dithiophosphate diethylammonium concentration in the pickling solution, the degree of corrosion of the sample intensified, and the C and O content of the sample surface increased accordingly.

[0054] Experimental Example 5 The corrosion acceleration rate of carbon steel Q235 was investigated at a pickling temperature of 25℃ for pickling solutions with effective concentrations of 0.04, 0.2, and 0.8 mmol / L prepared in Example 3, as well as for hydrochloric acid solutions without added O,O′-di(methyl)dithiophosphate diethylammonium, after standing for 0, 24, 48, and 72 h. Electrochemical tests were performed according to the methods described in "DL / T 523-2017 Evaluation Indicators and Test Methods for Application Performance of Chemical Cleaning Corrosion Inhibitors". The results are shown in Table 4.

[0055] Table 4. Stability test results of pickling solution

[0056] The results showed that the corrosion effect on low-carbon steel decreased with increasing standing time of the pickling solution. However, the addition of diethylammonium O,O′-di(methyl)dithiophosphate maintained the pickling effect on low-carbon steel and even promoted the degree of pickling corrosion. After standing for 72 hours, the effect of diethylammonium O,O′-di(methyl)dithiophosphate did not decrease, indicating that diethylammonium O,O′-di(methyl)dithiophosphate is stable in the pickling solution.

[0057] As can be seen from the above embodiments, the present invention provides a highly efficient metal corrosion accelerator and its application. Adding O,O′-di(methyl)dithiophosphate diethylammonium during the acidic corrosion process of metals can significantly accelerate the corrosion rate. This invention lays a solid foundation for subsequent processing, coating, welding, and other procedures of metal materials, and promotes the upgrading of the metal pickling industry towards more efficient and refined processing.

[0058] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made 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. Use of diethyl O,O'-dimethyl dithiophosphate as an acid pickling accelerator.

2. Use according to claim 1, characterized in that, The effective concentration of the diethyl O,O'-dimethyl dithiophosphate is 0.04-100 mmol / L.

3. A method of preparing a pickling solution, characterized by, The method comprises the following steps: The diethyl O,O'-dimethyl dithiophosphate is added into the inorganic acid to obtain the acid pickling solution.

4. The method of claim 3, wherein, The molar concentration ratio of the diethyl O,O'-dimethyl dithiophosphate to the inorganic acid is 0.04-100 mmol / L: 0.1-1 mol / L.

5. The method of claim 3, wherein, The inorganic acid is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, hydrofluoric acid, nitric acid and carbonic acid.

6. A method of pickling, characterized by, The method comprises the following steps: The metal to be treated is added into the acid pickling solution obtained in any one of claims 3-5, and soaked to obtain the metal after acid pickling; or The acid pickling solution obtained in any one of claims 3-5 is sprayed onto the surface of the metal to be treated to obtain the metal after acid pickling.

7. The method of claim 6, wherein, The temperature of the soaking or spraying is 30-50 ℃, and the soaking or spraying time is 0.1-4 h.

8. The method of claim 7, wherein, The metal to be treated comprises low carbon steel. The low carbon steel comprises one of Q195, Q215, Q235, Q255 and Q275.

10. Use according to claim 9, characterized in that, 9. Use of diethyl O,O'-dimethyl dithiophosphate in the preparation of an acid pickling additive. The effective concentration of the diethyl O,O'-dimethyl dithiophosphate is 0.04-100 mmol / L.

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