Reverse osmosis reducing agent as well as preparation method and application thereof

Abstract

The invention provides a reverse osmosis reducing agent and a preparation method and application thereof, and belongs to the technical field of reverse osmosis water treatment.The reverse osmosis reducing agent comprises a first reducing agent, a second reducing agent and a solvent; the first reducing agent is thiosulfate, and the second reducing agent is sulfite and / or bisulfite; the mass ratio of the first reducing agent to the second reducing agent is (1: 18)-(10: 1). The reverse osmosis reducing agent can be applied to reverse osmosis water treatment, the reverse osmosis reducing agent is added into reverse osmosis inlet water to be treated, and the reverse osmosis inlet water subjected to reduction treatment can be obtained after full reaction. The first reducing agent and the second reducing agent are compounded according to the specific mass ratio, so that the compounded reverse osmosis reducing agent can effectively inhibit the occurrence of advanced oxidation chain reaction while keeping high reducibility, and effective reduction of reverse osmosis inlet water can be realized by using a small amount of the reverse osmosis reducing agent.

Description

Technical Field

[0001] The present invention relates to the technical field of reverse osmosis water treatment, and in particular to a reverse osmosis reducing agent and a preparation method and application thereof. Background Art

[0002] The rapid development of new energy vehicles has increased demand for lithium-ion batteries, which in turn has driven the production of iron phosphate. The production process generates a large amount of wastewater, which requires a zero-discharge iron phosphate wastewater treatment system to prevent environmental pollution and resource waste.

[0003] In existing zero-discharge ferric phosphate wastewater treatment systems, reverse osmosis membrane systems are typically used for wastewater treatment and reuse. However, due to the ferric phosphate production process, even after pretreatment, the wastewater still contains a certain amount of oxidizing substances, such as free chlorine and hydrogen peroxide. To prevent these oxidizing substances in the wastewater from causing oxidation of the reverse osmosis membrane elements and thus affecting the membrane's salt rejection rate, a reducing agent is typically added to the reverse osmosis feed water to remove the oxidizing substances.

[0004] Currently, sulfites or bisulfites are commonly used as reducing agents to treat oxidizing substances in ferric phosphate wastewater. These reducing agents offer the advantages of high stability and rapid reaction with oxidizing substances such as free chlorine. However, as ferric phosphate production processes evolve to reduce costs and increase efficiency, changes in raw materials are occurring, leading to a continuous increase in the levels of excess metal ions in ferric phosphate wastewater. When the content of transition metal ions such as iron II, iron III, copper I, copper II, manganese II, chromium, and cobalt in the wastewater is too high and cannot be completely removed during the pretreatment process, the metal ions that are not removed will enter the reverse osmosis feed water and undergo an advanced oxidation chain reaction with sulfite / bisulfite as a reducing agent. This reaction has a high potential and strong oxidizing ability, and can easily oxidize low-valent stable substances in the water into oxidizing substances, for example, oxidizing manganese II in the water into manganese III, and oxidizing chloride ions into free chlorine, etc., thereby causing an abnormal increase in the ORP of the reverse osmosis feed water, which will not only cause oxidation of the reverse osmosis membrane elements, but also require an excess of reducing agent to suppress the production of these oxidizing substances, which in turn leads to excessive reducing agent usage. Summary of the Invention

[0005] In view of the technical problems existing in the background technology, the present application provides a reverse osmosis reducing agent and its preparation method and application, aiming to solve the technical problems that the existing reducing agents are prone to produce advanced oxidation chain reactions and the reducing agent dosage is too high.

[0006] In a first aspect, an embodiment of the present application provides a reverse osmosis reducing agent, comprising a first reducing agent, a second reducing agent, and a solvent; The first reducing agent is thiosulfate, and the second reducing agent is sulfite and / or bisulfite; the mass ratio of the first reducing agent to the second reducing agent is (1:18) to (10:1).

[0007] In the technical solution of the embodiment of the present application, by compounding the first reducing agent and the second reducing agent according to a specific mass ratio, the compounded reverse osmosis reducing agent can effectively suppress the occurrence of advanced oxidation chain reactions while maintaining strong reducing properties, and effective reduction of reverse osmosis water can be achieved with a smaller amount of reverse osmosis reducing agent.

[0008] In some embodiments, the pH of the reverse osmosis reducing agent is greater than 5 and less than 8.

[0009] In this embodiment, by regulating the pH value of the reverse osmosis reducing agent, it is possible to avoid the first reducing agent and the second reducing agent from reacting under conditions of low pH values, and to solve the problem of low reducing ability of the reverse osmosis reducing agent caused by excessively high pH values, so that the reverse osmosis reducing agent can efficiently reduce the reverse osmosis influent water.

[0010] In some embodiments, in the reverse osmosis reducing agent, the total mass concentration of the first reducing agent and the second reducing agent is 10% to 40%.

[0011] In this embodiment, the total mass concentration of the first reducing agent and the second reducing agent is regulated, which is beneficial to improving the reducing effect of the reverse osmosis reducing agent.

[0012] In some embodiments, the thiosulfate comprises at least one of sodium thiosulfate, potassium thiosulfate, and ammonium thiosulfate; and / or the sulfite comprises at least one of sodium sulfite, potassium sulfite, and ammonium sulfite; and / or the bisulfite comprises at least one of sodium bisulfite, potassium bisulfite, and ammonium bisulfite; and / or the solvent comprises water.

[0013] In this embodiment, the raw materials of thiosulfate, sulfite and bisulfite are relatively abundant, which is convenient for adjustment according to the actual production and application needs, and can make the formed reverse osmosis reducing agent have good reducing properties.

[0014] In a second aspect, an embodiment of the present application provides a method for preparing a reverse osmosis reducing agent, comprising the following steps: mixing a second reducing agent with a solvent, and then adding a first pH adjuster to adjust the pH value to a first predetermined range to obtain a first solution; adding a first reducing agent to the first solution, and then adding a second pH adjusting agent to adjust the pH value to a second predetermined range to obtain a reverse osmosis reducing agent; The first predetermined range is 6 to 7, and the second predetermined range is 5 to 8.

[0015] In the technical solution of the embodiment of the present application, by first mixing the second reducing agent with the solvent and adjusting the pH before adding the first reducing agent, a reaction between the first reducing agent and the second reducing agent when directly mixed can be effectively avoided. At the same time, by using the second pH adjuster after adding the first reducing agent, the pH value of the final reverse osmosis reducing agent can be adjusted to improve the reducing properties of the reverse osmosis reducing agent. Specifically, by adjusting the pH value of the first solution to a first predetermined range and adjusting the pH value of the final reverse osmosis reducing agent to a second predetermined range, the reaction between the first reducing agent and the second reducing agent at a low pH can be effectively avoided, and the effect of an excessively high pH value on the reducing properties can be avoided, thereby improving the stability and reducing properties of the reverse osmosis reducing agent.

[0016] In some embodiments, the first pH adjuster and the second pH adjuster both include at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia water, phosphoric acid solution, hydrochloric acid solution, and sulfuric acid solution; wherein the concentration range of sodium hydroxide solution, potassium hydroxide solution, hydrochloric acid solution, and sulfuric acid solution is 5% to 10%, and the concentration range of ammonia water and phosphoric acid solution is 5% to 20%.

[0017] In this embodiment, the first pH adjuster and the second pH adjuster can be commonly used acids and bases, and the selection range is wide. Among them, when using strong acids or strong bases as the corresponding pH adjusters, using relatively low concentrations can avoid excessive acid-base reactions.

[0018] In a third aspect, an embodiment of the present application provides a method for applying a reverse osmosis reducing agent, comprising the following steps: A reverse osmosis reducing agent is added to the reverse osmosis feed water to be treated, and reverse osmosis feed water after reduction treatment is obtained through reaction.

[0019] In this embodiment, by using the above-mentioned reverse osmosis reducing agent, oxidizing substances in the reverse osmosis feed water to be treated can be quickly removed, while effectively inhibiting advanced oxidation chain reactions, thereby achieving efficient reduction of the reverse osmosis feed water with a smaller amount of reducing agent.

[0020] In some embodiments, the ratio of the molar amount of the oxidizing substance contained in the reverse osmosis feed water to be treated to the total molar amount of the first reducing agent and the second reducing agent in the reverse osmosis reducing agent is 1:(2-4).

[0021] In this embodiment, by limiting the ratio of the total molar amount of the oxidizing substances in the reverse osmosis feed water to the total molar amount of each reducing agent in the reverse osmosis reducing agent, it is beneficial to adjust the amount of the reverse osmosis reducing agent according to the content of the oxidizing substances to ensure that the oxidizing substances in the reverse osmosis feed water are fully reduced.

[0022] In some embodiments, the pH value of the reverse osmosis inlet water after the reduction treatment is 5.5-6.5; and / or the ORP range of the reverse osmosis inlet water after the reduction treatment is 50-150 mV.

[0023] In this embodiment, limiting the pH value and / or ORP range of the reverse osmosis influent water after reduction treatment facilitates determining the treatment effectiveness of the reverse osmosis reducing agent. When the reverse osmosis influent water after reduction treatment meets the above conditions, it indicates that the added reverse osmosis reducing agent can effectively remove oxidizing substances from the reverse osmosis influent water while preventing the formation of precipitation caused by excessive reverse osmosis reducing agent residue, which could affect subsequent reverse osmosis treatment. If the measured ORP of the reverse osmosis influent water after reduction treatment is higher than the above range, it indicates that the dosage of reverse osmosis reducing agent is insufficient and the dosage needs to be increased until the ORP falls within the above range.

[0024] In some embodiments, when the pH value of the reverse osmosis influent after reduction treatment is 5.5, the ORP range is 100-150 mV; and / or, when the pH value of the reverse osmosis influent after reduction treatment is 6.5, the ORP range is 50-120 mV.

[0025] In this embodiment, by specifically limiting the ORP range corresponding to different pH values, the actual reduction conditions of reverse osmosis influent water with different pH values ​​can be more accurately reflected, so as to ensure that a better reduction effect can be achieved after the reverse osmosis reducing agent is added.

[0026] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. DETAILED DESCRIPTION

[0027] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application are intended to cover non-exclusive inclusions.

[0029] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0030] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0031] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0032] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0033] Commonly used reverse osmosis reducing agents are mainly sulfites or bisulfites. However, when the transition metal ion content in the wastewater is too high and the pretreatment process cannot completely remove it, the transition metal ions that are not removed will undergo an advanced oxidation chain reaction with the sulfite or bisulfite used as the reducing agent, which will not only cause oxidation of the reverse osmosis membrane element, but also require an excess of reducing agent to suppress the production of oxidizing substances, resulting in excessive dosage of reducing agent.

[0034] In order to solve the technical problems that existing reducing agents are prone to produce advanced oxidation chain reactions and the reducing agent dosage is too high, the present application provides a reverse osmosis reducing agent and its preparation method and application, wherein, by compounding sulfite and / or bisulfite with thiosulfate according to a certain mass ratio, the compounded reverse osmosis reducing agent can effectively inhibit the occurrence of advanced oxidation chain reactions while maintaining strong reducing properties, and effectively reduce the reverse osmosis water with a smaller dosage.

[0035] In a first aspect, an embodiment of the present application provides a reverse osmosis reducing agent, comprising a first reducing agent, a second reducing agent, and a solvent; wherein the first reducing agent is thiosulfate, and the second reducing agent is sulfite and / or bisulfite; the mass ratio of the first reducing agent to the second reducing agent is (1:18) to (10:1).

[0036] In the present application, if the first reducing agent is used alone, its reducing power is low and it is difficult to quickly neutralize oxidizing substances such as free chlorine in the water; if the second reducing agent is used alone, an advanced oxidation chain reaction will occur. The present application compounds the first reducing agent and the second reducing agent and regulates the ratio of the two so that they can work together, so that the compounded reverse osmosis reducing agent can not only quickly neutralize oxidizing substances in the water, but also effectively inhibit the occurrence of advanced oxidation chain reactions, thereby reducing the amount of reverse osmosis reducing agent used. Compared with the amount of reducing agent required when the second reducing agent is used alone, the reverse osmosis reducing agent compounded in the present application can reduce the amount of reducing agent used by 60% to 90%, effectively reducing the cost of use.

[0037] Specifically, the mass ratio of the first reducing agent to the second reducing agent can be 1:18, 1:15, 1:12, 1:9, 1:6, 1:3, 1:1, 2:1, 4:1, 6:1, 8:1, 10:1 or any value in the range of (1:18) to (10:1), preferably (1:12) to (6:1), and more preferably 4:1.

[0038] Furthermore, in some embodiments, the pH value of the reverse osmosis reducing agent is greater than 5 and less than 8.

[0039] In the present application, by regulating the pH value of the reverse osmosis reducing agent, the side reactions of the first reducing agent and the second reducing agent can be reduced while improving the reducing property of the reverse osmosis reducing agent. If the pH value of the reverse osmosis reducing agent is too low, thiosulfate and bisulfite react easily, and the lower the pH value, the faster the reaction; if the pH value of the reverse osmosis reducing agent is too high, its reducing property is relatively low, and it is impossible to quickly remove the oxidizing substances in the water. Among them, the way to adjust the pH value of the reverse osmosis reducing agent can be to add the required pH value regulator to the reverse osmosis reducing agent. Specifically, the pH value of the reverse osmosis reducing agent can be 5.1, 5.5, 6, 6.5, 7, 7.5, 7.9 or any value within the range of greater than 5 and less than 8; the pH value range of the reverse osmosis reducing agent can be further preferably 6~7, more preferably 6.5~6.8, to obtain a better reduction effect.

[0040] Furthermore, in some embodiments, in the reverse osmosis reducing agent, the total mass concentration of the first reducing agent and the second reducing agent is 10% to 40%.

[0041] In the present application, by regulating the total mass concentration of the first reducing agent and the second reducing agent, it is beneficial to improve the reduction effect of the reverse osmosis reducing agent. Under the condition that the dosing flow rate of the reverse osmosis reducing agent is the same, if the total mass concentration of the first reducing agent and the second reducing agent is too low, it will affect the content of the effective ingredient in the reverse osmosis reducing agent, resulting in a decrease in its reduction effect and an inability to quickly remove oxidizing substances in the water; if the total mass concentration of the first reducing agent and the second reducing agent is too high, side reactions are likely to occur, affecting the use effect of the reverse osmosis reducing agent. In actual applications, the dosing flow rate of the reverse osmosis reducing agent can also be adjusted according to the mass concentration of the reverse osmosis reducing agent, so that reverse osmosis reducing agents of different mass concentrations can achieve a good reduction effect.

[0042] Specifically, for the same reverse osmosis feed water, if a reverse osmosis reductant with a lower mass concentration is used, the reverse osmosis reductant needs to be added to the reverse osmosis feed water at a higher dosing rate; if a reverse osmosis reductant with a higher mass concentration is used, the reverse osmosis reductant needs to be added to the reverse osmosis feed water at a lower dosing rate. However, an excessively high dosing rate can easily result in excessive water consumption, while an excessively low dosing rate can cause uneven mixing due to the pulses of the dosing pump. Therefore, in order to achieve a better reduction effect at an appropriate dosing rate, the total mass concentration of the first and second reductants in the reverse osmosis reductant is preferably 10% to 40%. Specifically, the total mass concentration of the first and second reductants can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any value within the range of 10% to 40%.

[0043] Further, in some embodiments, the thiosulfate includes at least one of sodium thiosulfate, potassium thiosulfate, and ammonium thiosulfate; and / or, the sulfite includes at least one of sodium sulfite, potassium sulfite, and ammonium sulfite; and / or, the bisulfite includes at least one of sodium bisulfite, potassium bisulfite, and ammonium bisulfite; and / or, the solvent includes water.

[0044] In the present application, the preferred raw materials mentioned above all enable the reverse osmosis reducing agent to have good reducing properties. The raw material sources are relatively abundant, making it easy to adjust according to actual production and application needs. More specifically, when using the above-mentioned sulfites, since they are generally weakly alkaline, an appropriate amount of acid needs to be added to adjust the pH value; when using the above-mentioned bisulfites, an appropriate amount of base needs to be added to adjust the pH value.

[0045] In a second aspect, an embodiment of the present application provides a method for preparing a reverse osmosis reducing agent, comprising the following steps: Mixing a second reducing agent with a solvent, and then adding a first pH adjuster to adjust the pH value to a first predetermined range to obtain a first solution; adding a first reducing agent to the first solution, and then adding a second pH adjusting agent to adjust the pH value to a second predetermined range to obtain a reverse osmosis reducing agent; The first predetermined range is 6 to 7, and the second predetermined range is 5 to 8.

[0046] In the present application, by mixing the second reducing agent with the solvent, first mixing the second reducing agent with the solvent, adjusting the pH value and then adding the first reducing agent, it is possible to effectively avoid the reaction between the first reducing agent and the second reducing agent when they are directly mixed; by using the second pH adjuster after adding the first reducing agent, the pH value of the reverse osmosis reducing agent finally obtained can be regulated, which can avoid the first reducing agent and the second reducing agent from reacting under conditions of a low pH value, and can avoid the influence of an excessively high pH value on the reducing property of the reverse osmosis reducing agent, thereby improving the reducing property of the reverse osmosis reducing agent while reducing the side reactions of the first reducing agent and the second reducing agent.

[0047] Among them, by adjusting the pH value of the first solution to 6-7 and the pH value of the finally prepared reverse osmosis reducing agent to 5-8, it is possible to effectively avoid the reaction of the first reducing agent and the second reducing agent under conditions of low pH values, and also avoid the influence of excessively high pH values ​​on the reducing property, so that the prepared reverse osmosis reducing agent has both high stability and reducing property. Specifically, the first pH adjuster can adjust the pH value of the corresponding first solution to 6, 6.3, 6.5, 6.8, 7 or any value in the range of 6 to 7, more preferably adjusting the pH value of the solution to 6.5-6.8, and the second pH adjuster can adjust the pH value of the corresponding reverse osmosis reducing agent to 5, 5.3, 5.5, 5.8, 6, 6.3, 6.5, 6.8, 7, 7.3, 7.5, 7.8, 8 or any value in the range of 5 to 8, preferably adjusting the pH value of the solution to 6-7, more preferably adjusting the pH value of the solution to 6.5-6.8, so as to improve the stability and reducibility of the prepared reverse osmosis reducing agent.

[0048] Furthermore, in some embodiments, the first pH adjuster and the second pH adjuster both include at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia water, phosphoric acid solution, hydrochloric acid solution, and sulfuric acid solution; wherein the concentration range of sodium hydroxide solution, potassium hydroxide solution, hydrochloric acid solution, and sulfuric acid solution is 5% to 10%, and the concentration range of ammonia water and phosphoric acid solution is 5% to 20%.

[0049] In the present application, the first pH adjuster and the second pH adjuster can be commonly used acids and bases, with a wide range of choices. Specifically, when the second reducing agent is a sulfite, it is preferred to use at least one of a phosphoric acid solution, a hydrochloric acid solution, and a sulfuric acid solution as the first pH adjuster; when the second reducing agent is a bisulfite, it is preferred to use at least one of a sodium hydroxide solution, a potassium hydroxide solution, and ammonia water as the first pH adjuster. When a strong acid or a strong base is used as the first pH adjuster or the second pH adjuster, by controlling its concentration range to 5% to 10%, it is possible to avoid excessive acid-base reactions caused by excessive concentration; when a weak acid or a strong base is used as the first pH adjuster or the second pH adjuster, its concentration range can be controlled to 5% to 20%. More preferably, when ammonia water is used as the first pH adjuster and / or the second pH adjuster, it can also play an auxiliary reducing role to improve the reducing property of the reverse osmosis reducing agent.

[0050] In a third aspect, an embodiment of the present application provides a method for applying a reverse osmosis reducing agent, comprising the following steps: A reverse osmosis reducing agent is added to the reverse osmosis feed water to be treated, and reverse osmosis feed water after reduction treatment is obtained through reaction.

[0051] In the present application, by applying the above-mentioned reverse osmosis reducing agent to the reduction treatment process of reverse osmosis feed water, the oxidizing substances in the reverse osmosis feed water to be treated can be quickly removed, and at the same time, the advanced oxidation chain reaction can be effectively inhibited, thereby achieving efficient reduction of the reverse osmosis feed water with a smaller amount of reducing agent.

[0052] Furthermore, in some embodiments, the amount of the reverse osmosis reducing agent used can be determined based on the content of oxidizing substances in the reverse osmosis influent water, or based on the pH value and / or ORP range of the reverse osmosis influent water after reduction treatment.

[0053] When determining the amount of the reverse osmosis reducing agent based on the content of oxidizing substances in the reverse osmosis influent water, it is preferred to control the ratio of the molar amount of the oxidizing substances in the reverse osmosis influent water to the total molar amount of the first reducing agent and the second reducing agent in the reverse osmosis reducing agent to be 1:(2-4) to ensure that the oxidizing substances are fully reduced. Specifically, the oxidizing substance can be at least one of free chlorine and hydrogen peroxide; and the ratio of the molar amount of the oxidizing substance to the total molar amount of the first reducing agent and the second reducing agent in the reverse osmosis reducing agent can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, or any value within the range of 1:(2-4).

[0054] The method for determining the amount of the reverse osmosis reducing agent based on the pH value and / or ORP range of the reverse osmosis influent after the reduction treatment is preferably: gradually adding the reverse osmosis reducing agent to the reverse osmosis influent to be treated until the reverse osmosis influent after the reduction treatment meets the following conditions: The pH value of the reverse osmosis inlet water after the reduction treatment is 5.5-6.5; and / or the ORP range of the reverse osmosis inlet water after the reduction treatment is 50-150 mV.

[0055] When the reverse osmosis influent water after reduction treatment meets the above conditions, it indicates that the added reverse osmosis reducing agent can effectively remove the oxidizing substances in the reverse osmosis influent water, and at the same time can prevent the excessive residual reverse osmosis reducing agent from causing precipitation and affecting the subsequent reverse osmosis treatment.

[0056] Preferably, when the pH value of the reverse osmosis inlet water after reduction treatment is 5.5, the ORP range is 100-150 mV; and / or, when the pH value of the reverse osmosis inlet water after reduction treatment is 6.5, the ORP range is 50-120 mV. By comprehensively considering the pH value and ORP value of the reverse osmosis inlet water after reduction treatment, the actual reduction status of the reverse osmosis inlet water can be more accurately reflected, so as to determine whether the dosage of the reverse osmosis reducing agent is appropriate. This ensures that the reverse osmosis reducing agent fully reduces the oxidizing substances in the reverse osmosis inlet water while avoiding the impact of excessive addition of the reverse osmosis reducing agent, thereby achieving a better reduction effect at a lower cost.

[0057] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0058] 1. Preparation method Example 1 This embodiment provides a method for preparing a reverse osmosis reducing agent, comprising the following steps: S1. A second reducing agent, sodium bisulfite, was added to water and fully dissolved, followed by addition of a first pH adjusting agent (8% sodium hydroxide solution) to adjust the pH of the solution to 6.5 to obtain a first solution; S2. A first reducing agent, sodium thiosulfate pentahydrate, is added to the first solution to achieve a mass ratio of the first reducing agent to the second reducing agent of 4:1. A second pH adjuster (10% mass concentration of aqueous ammonia) is then added to adjust the pH of the solution to 6.8, thereby obtaining a reverse osmosis reducing agent. The total mass concentration of the first and second reducing agents in the reverse osmosis reducing agent is 25%.

[0059] Examples 2 to 7 and Comparative Examples 1 to 4 Examples 2 to 7 and Comparative Examples 1 to 4 respectively provide a method for preparing a reverse osmosis reducing agent. Compared with Example 1, the only difference is that the mass ratio of the first reducing agent, sodium thiosulfate pentahydrate, to the second reducing agent, sodium bisulfite, is changed. The corresponding mass ratios in each embodiment and comparative example are shown in Table 1. The remaining steps are the same as in Example 1 and are not repeated here.

[0060] Table 1 Mass ratio of the first reducing agent to the second reducing agent in Examples 2 to 7 and Comparative Examples 1 to 4 Among them, Comparative Example 1 means that the first reducing agent is not added in step S2, and the main component of the obtained reverse osmosis reducing agent is only sodium bisulfite; Comparative Example 2 means that the second reducing agent is not added in step S1, and the main component of the obtained reverse osmosis reducing agent is only sodium thiosulfate pentahydrate.

[0061] Examples 8-12 and Comparative Examples 5-6 Examples 8 to 12 and Comparative Examples 5 to 6 each provide a method for preparing a reverse osmosis reducing agent. Compared with Example 1, the only difference is that the pH values ​​of the first solution and the reverse osmosis reducing agent are changed by adjusting the first pH adjuster and the second pH adjuster. The pH values ​​of the first solution and the reverse osmosis reducing agent in each example and comparative example are shown in Table 2. The remaining steps are consistent with Example 1 and are not repeated here.

[0062] Table 2 pH values ​​of the first solution and the reverse osmosis reducing agent in Examples 8 to 12 and Comparative Examples 5 to 6 Examples 13-14 Examples 13 to 14 respectively provide a method for preparing a reverse osmosis reducing agent. Compared with Example 1, the only difference is that the total mass concentration of the first reducing agent and the second reducing agent in the reverse osmosis reducing agent is changed by adjusting the mass of water in step S1. The corresponding total mass concentrations in each embodiment are shown in Table 3. The remaining steps are consistent with Example 1 and are not repeated here.

[0063] Table 3 Total mass concentration of the first reducing agent and the second reducing agent in Examples 13-14 Application Examples 1 to 20 The reverse osmosis reducing agents prepared in the above Examples 1 to 14 and Comparative Examples 1 to 6 were respectively applied to the treatment of reverse osmosis influent water to obtain Application Examples 1 to 20.

[0064] The only difference between Application Examples 1 to 20 is the reverse osmosis reducing agent used. The reverse osmosis influent water to be treated and the specific application methods are exactly the same, including the following steps: A reverse osmosis reducing agent is added to the reverse osmosis feed water to be treated, and after sufficient reaction, the reverse osmosis feed water after reduction treatment is obtained.

[0065] The reverse osmosis influent to be treated has a pH of 5.8 and an ORP of 182 mV, and contains free chlorine as an oxidizing substance (free chlorine is calculated as Cl2, and its mass concentration is measured to be 3 ppm, which is converted into a molar concentration of approximately 0.0423 mmol / L). The ratio of the molar amount of the free chlorine to the total molar amount of the first reducing agent and the second reducing agent in the added reverse osmosis reducing agent is 1:3.

[0066] Application Examples 21-24 Application Examples 21 to 24 are all directed to the reverse osmosis reducing agent prepared in Example 1, and each provides an application method of a reverse osmosis reducing agent. The only difference from Application Example 1 is that the amount of the reverse osmosis reducing agent is changed. The ratio of the molar amount of free chlorine to the total molar amount of the first reducing agent and the second reducing agent in the added reverse osmosis reducing agent in Application Examples 21 to 24 is shown in Table 4.

[0067] Table 4 Ratio of the molar amount of free chlorine to the total molar amount of the first reducing agent and the second reducing agent in the reverse osmosis reducing agent added in Application Examples 21 to 24 Application Example 25 Application Example 25 provides an application method of a reverse osmosis reducing agent. The reverse osmosis reducing agent (i.e., single sodium bisulfite) prepared in Comparative Example 1 is added to the reverse osmosis influent to be treated. By changing the dosage of the reverse osmosis reducing agent, the ORP value of the reverse osmosis influent after reduction treatment is made consistent with the ORP value of the reverse osmosis influent after reduction treatment in Application Example 1.

[0068] 2. Test Method 1. pH value test: Use a pH meter to test the pH value of the reverse osmosis influent in each application example.

[0069] 2. ORP test: Use an ORP meter to test the ORP value of the reverse osmosis inlet water in each application example.

[0070] 3. Analysis of test results of each application case The dosage of the reverse osmosis reducing agent used in Examples 1 to 25 (measured as the total molar concentration of the first reducing agent and the second reducing agent contained in the reverse osmosis influent), the addition ratio (measured as the ratio of the total mass of the added first reducing agent and the second reducing agent to the influent mass of the reverse osmosis influent), and the pH value and ORP value of the reverse osmosis influent after reduction treatment were tested. The results are shown in Table 5.

[0071] Table 5 Test results of application examples 1 to 25 As can be seen from Table 5, factors such as the mass ratio of the first and second reducing agents in the reverse osmosis reducing agent, the pH value of each step in the preparation of the reverse osmosis reducing agent, the total mass concentration of the first and second reducing agents in the reverse osmosis reducing agent, and the molar ratio of the oxidizing substance to the reverse osmosis reducing agent all affect the actual application effect of the reverse osmosis reducing agent. This results in significant differences in the ORP values ​​of the reverse osmosis influent water after reduction treatment in various application examples, while the pH values ​​of the reverse osmosis influent water are similar, all around 5.5. Under these pH conditions, an ORP value within the range of 100-150 mV indicates a good reduction effect and is unlikely to produce sulfide precipitation. If the ORP value is below this range, sulfide precipitation is easily produced by the reaction. If the ORP value is above this range, it indicates that the reverse osmosis influent water still contains a certain amount of oxidizing substances, and the reduction effect is not ideal. The higher the ORP value, the higher the content of oxidizing substances in the reverse osmosis influent water.

[0072] Specifically, a comparison of Application Examples 1-7 and Application Examples 15-18 shows that as the proportion of the first reducing agent in the reverse osmosis reducing agent increases, the ORP value of the reverse osmosis influent water after reduction treatment generally decreases and then increases. When the reverse osmosis reducing agent used was sodium bisulfite alone, the ORP value of the reverse osmosis influent water after reduction treatment was the highest, reaching 631 mV. This indicates that the addition of this reverse osmosis reducing agent triggered an advanced oxidation chain reaction, resulting in the generation of a large amount of oxidizing substances in the reverse osmosis influent water. On the basis of adding sodium bisulfite as the second reducing agent, adding sodium thiosulfate pentahydrate as the first reducing agent is beneficial to reducing the ORP value of the reverse osmosis inlet water. However, when the proportion of anhydrous sodium thiosulfate is too low, the effect of reducing the ORP value is not obvious. When the mass ratio of sodium thiosulfate pentahydrate to sodium bisulfite reaches 1:18, the ORP value of the reverse osmosis inlet water can be significantly reduced; when the mass ratio of sodium thiosulfate pentahydrate to sodium bisulfite reaches 4:1, the ORP value of the reverse osmosis inlet water reaches the lowest. Thereafter, continuing to increase the proportion of sodium thiosulfate pentahydrate will instead lead to an increase in the ORP value of the reverse osmosis inlet water.

[0073] By comparing Application Examples 1, 8-12, and 19-20, it can be seen that the ORP value of the reverse osmosis influent water after reduction treatment increases with the increase in the pH value of the reverse osmosis reducing agent. When the pH value of the reverse osmosis reducing agent is 4, the ORP value of the reverse osmosis influent water after reduction treatment is only 89 mV, indicating that it easily reacts to produce sulfide precipitation; when the pH value of the reverse osmosis reducing agent increases to 9, the excessively high ORP value indicates that its reduction effect is poor. By controlling the pH value of the reverse osmosis reducing agent between 5.1 and 7.9, the various embodiments of the present application are conducive to achieving a good reduction effect while preventing sulfide precipitation.

[0074] By comparing Application Example 1 with Application Examples 13-14, it can be seen that, under the condition that the total molar amount of the first and second reducing agents in the added reverse osmosis reducing agent remains unchanged, adjusting the total mass concentration of the first and second reducing agents in the reverse osmosis reducing agent has little effect on the final reduction effect. By comparing Application Example 1 with Application Examples 21-24, it can be seen that as the amount of reverse osmosis reducing agent increases, the ORP value of the reverse osmosis influent water after reduction treatment gradually decreases, indicating that too little reverse osmosis reducing agent will result in an excessively high ORP value and a poor reduction effect, while an excessive amount of reverse osmosis reducing agent will easily lead to the formation of sulfide precipitation.

[0075] By comparing Application Example 1 and Application Example 25, it can be seen that in order to achieve the same reduction effect, when only sodium bisulfite is used as the reverse osmosis reducing agent, its dosage needs to reach 109.99 ppm, while the dosage of the reverse osmosis reducing agent provided in Example 1 is only 18.18 ppm, which is nearly 83% lower than the dosage of sodium bisulfite, and the raw material cost is also significantly reduced.

[0076] From the above analysis, it can be seen that the reverse osmosis reducing agent prepared in each embodiment of the present application can effectively inhibit the occurrence of advanced oxidation chain reactions while maintaining strong reducing properties, and effective reduction of reverse osmosis water can be achieved with a smaller amount of reverse osmosis reducing agent.

[0077] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A reverse osmosis reducing agent, characterized in that: comprising a first reducing agent, a second reducing agent, and a solvent; The first reducing agent is thiosulfate, and the second reducing agent is sulfite and / or bisulfite; the mass ratio of the first reducing agent to the second reducing agent is (1:18) to (10:1).

2. The reverse osmosis reducing agent according to claim 1, characterized in that The pH value of the reverse osmosis reducing agent is greater than 5 and less than 8.

3. The reverse osmosis reducing agent according to claim 1, characterized in that In the reverse osmosis reducing agent, the total mass concentration of the first reducing agent and the second reducing agent is 10% to 40%.

4. The reverse osmosis reducing agent according to claim 1, characterized in that The thiosulfate includes at least one of sodium thiosulfate, potassium thiosulfate, and ammonium thiosulfate; and / or, The sulfite includes at least one of sodium sulfite, potassium sulfite and ammonium sulfite; and / or, The bisulfite includes at least one of sodium bisulfite, potassium bisulfite, and ammonium bisulfite; and / or, The solvent includes water.

5. A method for preparing a reverse osmosis reducing agent according to any one of claims 1 to 4, characterized in that: The steps include: mixing a second reducing agent with a solvent, and then adding a first pH adjuster to adjust the pH value to a first predetermined range to obtain a first solution; adding a first reducing agent to the first solution, and then adding a second pH adjusting agent to adjust the pH value to a second predetermined range to obtain a reverse osmosis reducing agent; The first predetermined range is 6 to 7, and the second predetermined range is 5 to 8.

6. The method for preparing a reverse osmosis reducing agent according to claim 5, characterized in that: The first pH adjuster and the second pH adjuster both include at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia water, phosphoric acid solution, hydrochloric acid solution, and sulfuric acid solution; wherein the concentration range of the sodium hydroxide solution, potassium hydroxide solution, hydrochloric acid solution, and sulfuric acid solution is 5% to 10%, and the concentration range of the ammonia water and phosphoric acid solution is 5% to 20%.

7. A method for using the reverse osmosis reducing agent according to any one of claims 1 to 4 or the reverse osmosis reducing agent prepared by the method according to any one of claims 5 to 6, characterized in that: The steps include: The reverse osmosis reducing agent is added to the reverse osmosis feed water to be treated, and the reverse osmosis feed water after reduction treatment is obtained through reaction.

8. The application method of the reverse osmosis reducing agent according to claim 7, characterized in that: The ratio of the molar amount of the oxidizing substance contained in the reverse osmosis influent to be treated to the total molar amount of the first reducing agent and the second reducing agent in the reverse osmosis reducing agent is 1:(2-4).

9. The application method of the reverse osmosis reducing agent according to claim 7, characterized in that: The pH value of the reverse osmosis influent after the reduction treatment is 5.5-6.5; and / or, The ORP range of the reverse osmosis influent after the reduction treatment is 50-150 mV.

10. The application method of the reverse osmosis reducing agent according to claim 7, characterized in that: When the pH value of the reverse osmosis influent after the reduction treatment is 5.5, the ORP range is 100-150 mV; and / or When the pH value of the reverse osmosis influent after the reduction treatment is 6.5, the ORP range is 50-120 mV.

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