Device and method suitable for performance evaluation of reverse osmosis scale inhibitor

Abstract

The invention discloses a device and a method suitable for performance evaluation of a reverse osmosis scale inhibitor, and belongs to the technical field of chemical performance evaluation. The device comprises a power control acquisition system, and a drug storage system, a reaction generation system and a reverse osmosis membrane system which are connected in sequence, wherein the power control acquisition system is electrically connected with the drug storage system, the reaction generation system and the reverse osmosis membrane system respectively; the reaction generation system comprises a reaction tank, a stirring rod, a pH sensor, a three-way valve and an outflow pipeline; the reverse osmosis membrane system comprises a reverse osmosis membrane; a connecting pipeline between the medicine storage system and the reaction generation system extends into the reaction tank, the stirring rod is arranged inside the reaction tank, the pH sensor is arranged outside the reaction tank, the bottom of the tank wall on one side of the reaction tank is connected with an outflow pipeline in a penetrating manner, and the outflow pipeline is connected with an inlet of the pH sensor and an inlet of the reverse osmosis membrane through a three-way valve; an outlet of the pH sensor penetrates through a top cover body of the reaction tank and extends into the reaction tank. The device is high in automation degree and capable of continuously monitoring water quality changes and accurately capturing chemical reaction mutation points, and the method combines the supersaturation degree of calcium carbonate and the water production rate of the reverse osmosis membrane to comprehensively evaluate the performance of the scale inhibitor.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical performance evaluation technology, specifically relating to an apparatus and method suitable for evaluating the performance of reverse osmosis antiscalants. Background Technology

[0002] Under applied pressure, reverse osmosis feed water passes through a selective semi-permeable membrane, where contaminants such as salt and organic matter are retained, thus producing fresh water. This technology is called reverse osmosis and is now widely used in urban wastewater reuse, boiler water desalination, and ultrapure water production. However, over time, residual contaminants can clog the pores of the selective semi-permeable membrane, even permanently damaging the membrane element. Furthermore, membrane manufacturing is complex and extremely expensive, accounting for more than 50% of the total equipment cost. Therefore, it is necessary to use appropriate scale inhibitors for water pretreatment to control carbonate scale, sulfate scale, calcium fluoride scale, and silica scale, softening the water before it enters the reverse osmosis membrane element, thereby reducing the membrane load and extending its lifespan.

[0003] There are many types of scale inhibitors on the market, with varying quality. If they are used directly without scientific screening and evaluation, they will not only fail to effectively inhibit scaling but may also damage membrane elements. Currently, scale inhibition performance evaluation methods are divided into static and dynamic methods, each with its own characteristics and limitations. Static methods mostly borrow from the evaluation methods of scale inhibitors in circulating cooling water under hot-cold exchange and evaporation concentration scenarios. They are simple, easy to implement, and have a short testing time, but they differ significantly from the reverse osmosis technology's use of membranes to intercept impurities and deposit them on the surface, thus failing to effectively reproduce the reverse osmosis process. Dynamic methods, on the other hand, use equipment such as temperature control and dosing pumps to simulate actual operating conditions as closely as possible through long-term dynamic circulation. However, both methods work by adding a solution containing impurity ions such as calcium, magnesium, and silicon, along with a scale inhibitor solution, to the water. As the concentration of impurity ions increases, precipitation is observed in the water. Critical impurity ion concentrations, precipitation amounts, or turbidity are obtained through multiple sampling titration analyses or intermittent detection modes using absorbance measurements to evaluate the scale inhibitor performance. For example, Chinese invention patent CN112557318A describes a method for rapidly evaluating the scale inhibition performance of reverse osmosis antiscalants. This method involves adding a solution containing scale-forming ions and the antiscalant to test water, using a sudden change in absorbance as a precipitation signal, and calculating the critical scale-forming ion concentration to determine the scale inhibition performance. However, this method has drawbacks: it cannot automatically and continuously monitor water quality changes; it cannot accurately capture abrupt changes in chemical reactions; and it only considers conventional inorganic precipitation reactions, neglecting the secondary fouling of membrane elements caused by the gelatinous reactants that some polymeric organic antiscalants may produce when encountering cationic polymeric electrolytes. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide an apparatus and method for evaluating the performance of reverse osmosis antiscalants. The apparatus is highly automated, can continuously monitor water quality changes, and accurately capture chemical reaction mutation points. The method combines the supersaturation of calcium carbonate and the permeate rate of the reverse osmosis membrane as dual indicators to comprehensively evaluate the performance of antiscalants.

[0005] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a device suitable for evaluating the performance of reverse osmosis antiscalants, comprising a power control and acquisition system and a drug storage system, a reaction generation system, and a reverse osmosis membrane system connected in sequence. The power control and acquisition system is electrically connected to the drug storage system, the reaction generation system, and the reverse osmosis membrane system, respectively. The reaction generation system includes a reaction tank, a stirring rod, a pH sensor, a three-way valve, and an outlet pipe. The reverse osmosis membrane system includes a reverse osmosis membrane. The connecting pipe between the drug storage system and the reaction system extends into the reaction tank. The stirring rod is located inside the reaction tank, and the pH sensor is located outside the reaction tank. An outflow pipe is connected through the bottom of one side wall of the reaction tank. The outflow pipe is connected to the inlet of the pH sensor and the inlet of the reverse osmosis membrane via a three-way valve. The outlet of the pH sensor extends into the reaction tank through the top cover.

[0006] In one embodiment, the reaction tank is a double-layer transparent glass tank, which consists of an inner transparent glass tank and an outer transparent glass tank. There is an interlayer between the inner and outer transparent glass tanks. An inlet is provided on the lower part of one side of the outer transparent glass tank, and an outlet is provided on the upper part of the opposite side. The interlayer is used to circulate and keep the temperature of the water.

[0007] In one embodiment, the reaction tank includes a double-layered transparent glass tank body and a cover located above the double-layered transparent glass tank body. The double-layered transparent glass tank body and the cover body are threaded together, and an elastic sealing gasket is provided between the double-layered transparent glass tank body and the cover body.

[0008] In one embodiment, the cover has a first opening, a second opening, a third opening, and at least one pressure-through hole that can be selectively opened or blocked. The connecting pipe between the drug storage system and the reaction system extends into the reaction tank through the first opening. The stirring rod is embedded in the reaction tank through the second opening. The outlet of the pH sensor extends into the reaction tank through the third opening.

[0009] In one embodiment, the reverse osmosis membrane system further includes a level cup disposed directly below the outlet of the reverse osmosis membrane; the power control acquisition system is electrically connected to the pumps on the connecting pipelines between the stirring rod, pH sensor, three-way valve, chemical storage system and reaction generation system, the pumps on the outflow pipeline between the reaction tank and the three-way valve, and the pumps on the connecting pipeline between the three-way valve and the inlet of the reverse osmosis membrane.

[0010] The present invention also provides a method for evaluating the performance of reverse osmosis antiscalants, based on the above-mentioned apparatus for evaluating the performance of reverse osmosis antiscalants, comprising the following steps: S1: Prepare calcium chloride solution and sodium bicarbonate solution; dilute the scale inhibitor to be evaluated to prepare scale inhibitor solution; load sodium bicarbonate solution into the drug storage system, add calcium chloride solution and scale inhibitor solution into the reaction tank, assemble the stirring rod, and insert pH sensor; S2: Start the drug storage system, reaction system, and power control acquisition system. Pump the sodium bicarbonate solution in the drug storage system to continuously drip into the reaction tank. Switch the three-way valve. The mixed solution in the reaction tank passes through the pH sensor from bottom to top. Record the pH sensor data changes in real time. Stop the experiment when the pH value changes from rising to falling and shows an inflection point. Turn off the pH sensor and drug storage system. Record the maximum pH value before the pH decrease and the corresponding volume of sodium bicarbonate solution consumed when the pH value is at the maximum value. Calculate the supersaturation of calcium carbonate. S3: Start the reaction generation system, reverse osmosis membrane system, and power control and acquisition system; switch the three-way valve; the mixed solution in the reaction tank flows through the reverse osmosis membrane; collect and record the volume of reverse osmosis permeate and the corresponding reverse osmosis permeate consumption time; and calculate the permeate rate. S4: The performance of reverse osmosis antiscalants is ranked and evaluated based on calcium carbonate supersaturation and permeate rate.

[0011] In one embodiment, the formula for calculating the supersaturation of calcium carbonate is as follows:

[0012] In the above formula, S This represents the supersaturation degree of calcium carbonate. C 1 represents the concentration of the calcium chloride solution, in mol / L; C 2 represents the concentration of the sodium bicarbonate solution, in mol / L; V 1 represents the volume of the calcium chloride solution, in mL; V 2 represents the volume of sodium bicarbonate solution consumed at the maximum pH value, in mL. V 3 represents the volume of the scale inhibitor solution, in mL; pH This is the maximum pH value.

[0013] In one embodiment, the formula for calculating the water production rate is as follows:

[0014] In the above formula, v This represents the water production rate, expressed in L / h. V 4 represents the volume of reverse osmosis permeate, in liters (L). t The time consumed for reverse osmosis permeate is expressed in hours (h).

[0015] In one embodiment, the supersaturation of calcium carbonate is positively correlated with the performance of the reverse osmosis antiscalant, and the permeate rate is also positively correlated with the performance of the reverse osmosis antiscalant.

[0016] In one embodiment, the concentration of the calcium chloride solution is 0.001~0.03 mol / L, the concentration of the sodium bicarbonate solution is 0.1~3 mol / L, and the concentration of the scale inhibitor solution is 0.3~10 mg / mL.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a device for evaluating the performance of reverse osmosis antiscalant. The device, through a reaction generation system including a reaction tank and a pH sensor, can monitor pH parameters related to calcium carbonate supersaturation, accurately capturing abrupt chemical reaction changes. The reverse osmosis membrane system can then monitor the permeate flow rate, forming a dual-indicator evaluation system of calcium carbonate supersaturation and membrane permeate flow rate, providing rating indicators for a comprehensive evaluation of antiscalant performance. By switching via a three-way valve, the antiscalant first reacts fully with the solution to be treated through the reaction generation system, and then the reacted solution is transported to the reverse osmosis membrane. This allows for the detection of abnormal reactants (such as colloids) between the antiscalant and water components, preventing unreacted impurities from directly entering the membrane system and providing a proactive safeguard against secondary membrane fouling. Real-time monitoring of the reverse osmosis membrane's permeate flow rate through a power control and acquisition system allows for a direct assessment of the extent to which colloid reactants cause organic fouling or other damage to the reverse osmosis membrane. A sharp drop in the permeate flow rate indicates that the colloid reactants have severely fouled the membrane element, thus accurately determining the risk of the antiscalant causing secondary membrane fouling. The power control and acquisition system is electrically connected to the stirring rod, pH sensor, three-way valve and pumps on the corresponding pipelines. It can automatically control the delivery of drugs and the reaction process (such as stirring). At the same time, it can continuously monitor the pH value of the solution in the reaction tank in real time through the pH sensor.

[0018] This invention provides a method for evaluating the performance of reverse osmosis antiscalants. This method, based on the characteristic that the pH of reverse osmosis feed water is typically neutral or weakly alkaline, incorporates corresponding chemical reaction conditions and suitable monitoring methods. In a neutral or weakly alkaline environment, carbonic acid mainly reacts as bicarbonate ions (HCO3-). - It exists in the form of CO3, rather than carbonate ions.2- Bicarbonate ions undergo hydrolysis to produce hydroxide ions (OH-). - When bicarbonate ions are continuously added dropwise to bicarbonate (H₂CO₃), the bicarbonate ions promote the forward hydrolysis reaction, resulting in the formation of hydroxide ions (OH⁻). - As the amount of calcium carbonate (H2CO3) gradually increases, the pH value of the solution rises accordingly. Simultaneously, carbonic acid accumulates until it reaches saturation and precipitates. After this point, the pH value changes from rising to falling, exhibiting a clear inflection point. This method, by continuously monitoring changes in solution pH, avoids the shortcomings of traditional methods that rely on visual judgment of the experimental endpoint or offline measurement of impurity ion concentration, precipitation amount, or turbidity. It achieves automated real-time capture of abrupt chemical reaction changes, significantly improving the accuracy and efficiency of evaluation. Furthermore, this invention also includes an experiment where water pretreated with scale inhibitor flows through a reverse osmosis membrane. By monitoring and evaluating changes in the permeate rate, it determines whether the scale inhibitor will cause organic fouling or other damage to the reverse osmosis membrane, achieving a comprehensive evaluation of the scale inhibitor's performance. This makes the evaluation results more comprehensive and reliable, and the method has certain implementation and promotion value. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a device for evaluating the performance of reverse osmosis antiscalants provided by the present invention. The components are: 1-scale inhibitor solution storage tank; 2-reaction tank; 3-stirring rod; 4-pH sensor; 5-three-way valve; 6-reverse osmosis membrane; 7-liquid level cup; 8-control device. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of 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 skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1 The present invention provides an apparatus suitable for evaluating the performance of reverse osmosis antiscalant, comprising a drug storage system A, a reaction generation system B, a reverse osmosis membrane system C, a power control and acquisition system D, as well as pumps, valves and other connecting parts.

[0023] The drug storage system A mainly includes a scale inhibitor solution storage tank 1, a connecting pipeline between the drug storage system A and the reaction generation system B, a connecting pipeline between the drug storage system and the reaction generation system extending into the reaction tank 2, and a pump installed on the connecting pipeline between the drug storage system and the reaction generation system.

[0024] The reaction system B mainly includes a reaction tank 2, a stirring rod 3, a pH sensor 4, a three-way valve 5, an outflow pipe, a pump on the outflow pipe between the reaction tank 2 and the three-way valve 5, and a pump on the connecting pipe between the three-way valve 5 and the inlet of the reverse osmosis membrane 6. The stirring rod 3 is located inside the reaction tank 2, and the pH sensor 4 is located outside the reaction tank 2. An outflow pipe is connected through the bottom of one side wall of the reaction tank 2. The outflow pipe is connected to the inlet of the pH sensor 4 and the inlet of the reverse osmosis membrane 6 via the three-way valve 5. The outlet of the pH sensor 4 extends into the reaction tank 2 through the top cover of the reaction tank 2.

[0025] The reverse osmosis membrane system C mainly includes a reverse osmosis membrane 6 and a liquid level cup 7 located directly below the outlet of the reverse osmosis membrane 6.

[0026] The power control and acquisition system D mainly includes a control device 8, which can control the stirring rod 3, the three-way valve 5 and all pumps, and collect and display data from the pH sensor 4. The power control and acquisition system is electrically connected to the pumps on the connecting pipelines between the stirring rod 3, the pH sensor 4, the three-way valve 5, the drug storage system and the reaction system, the pumps on the outflow pipeline between the reaction tank 2 and the three-way valve 5, and the pumps on the connecting pipeline between the three-way valve 5 and the inlet of the reverse osmosis membrane 6.

[0027] Furthermore, reaction tank 2 is a double-layered transparent glass tank made of acid and alkali resistant transparent glass material (for easy observation). The double-layered transparent glass tank consists of an inner transparent glass tank and an outer transparent glass tank, with an interlayer between them. A constant-temperature water inlet is located at the lower part of one side of the outer transparent glass tank, and a constant-temperature water outlet is located at the upper part of the opposite side. The constant-temperature water circulation within the interlayer achieves constant temperature control of the solution to be tested. The purpose of the double-layered transparent glass tank is to add the function of a constant-temperature water bath to the single-layer design. The constant-temperature water circulation through the interlayer keeps the solution to be tested (in the inner layer) at a constant temperature.

[0028] The double-layered transparent glass pool is equipped with a detachable cover (glass) on top. The cover and the pool body of the double-layered transparent glass pool are sealed together by threaded compression. An elastic sealing gasket made of silicone or rubber is built into the connection surface between the pool body and the cover. When tightened, the gasket is deformed by pressure to fill the tiny gaps and ensure the airtightness of the reaction system.

[0029] The cover has at least four functional openings. The connecting pipe between the drug storage system and the reaction system extends into the reaction tank 2 through the first opening, which facilitates solution transfer between the two systems. The second opening is for inserting a stirring rod 3 with a built-in sealed bearing. The third opening is for connecting a pH sensor 4 with a reflux structure. The fourth opening is at least one pressure port that can be selectively opened or closed.

[0030] Specifically, the pH sensor 4 forms a circulation loop with the reaction tank 2 through the outflow pipe and the three-way valve 5. The solution to be tested flows from bottom to top through the electrode detection area through the bottom inlet of the pH sensor 4, and then flows back into the reaction tank 2 through the top outlet of the pH sensor 4, ensuring sufficient contact between the electrodes while maintaining a constant total volume of the reaction system.

[0031] This invention also provides a method for evaluating the performance of reverse osmosis antiscalants, comprising the following steps: S1: Prepare calcium chloride solution and sodium bicarbonate solution; dilute the scale inhibitor to be evaluated to prepare scale inhibitor solution; load sodium bicarbonate solution into the drug storage system, add calcium chloride solution and scale inhibitor solution into reaction tank 2, assemble stirring rod 3, and insert pH sensor 4. S2: Turn on the drug storage system, reaction system, and power control acquisition system. Pump the sodium bicarbonate solution in the drug storage system to continuously add it dropwise to the reaction tank 2. Switch the three-way valve 5. The mixed solution in the reaction tank 2 passes through the pH sensor 4 from bottom to top. Record the data changes of the pH sensor 4 in real time. Stop the experiment when the pH value changes from rising to falling and shows an inflection point. Turn off the pH sensor 4 and the drug storage system. Record the maximum pH value before the pH decrease and the corresponding volume of sodium bicarbonate solution consumed when the pH value is at the maximum value. Calculate the supersaturation of calcium carbonate. S3: Start the reaction generation system, reverse osmosis membrane system, and power control and acquisition system; switch the three-way valve 5; the mixed solution in the reaction tank 2 flows through the reverse osmosis membrane 6; receive and record the volume of reverse osmosis permeate and the corresponding reverse osmosis permeate consumption time; and calculate the permeate rate. S4: The performance of reverse osmosis antiscalants was ranked and evaluated based on calcium carbonate supersaturation and permeate rate; among them, calcium carbonate supersaturation and permeate rate were positively correlated with the performance of reverse osmosis antiscalants.

[0032] The formula for calculating the supersaturation of calcium carbonate is as follows: (1) In the above formula, S This represents the supersaturation degree of calcium carbonate. C 1 represents the concentration of the calcium chloride solution, in mol / L; C 2 represents the concentration of the sodium bicarbonate solution, in mol / L; V 1 represents the volume of the calcium chloride solution, in mL; V 2 represents the volume of sodium bicarbonate solution consumed at the maximum pH value, in mL. V 3 represents the volume of the scale inhibitor solution, in mL; pH This is the maximum pH value.

[0033] The formula for calculating the above water production rate is as follows: (2) In the above formula, v This represents the water production rate, expressed in L / h. V 4 represents the volume of reverse osmosis permeate, in liters (L). t The time consumed for reverse osmosis permeate is expressed in hours (h).

[0034] In one embodiment, a method for evaluating the performance of reverse osmosis antiscalants is provided, the specific steps of which are as follows: Step 1: Weigh the reagent (analytical grade), dissolve and dilute to a final volume to prepare a solution with the following concentration: C A calcium chloride solution with a concentration of 1 C2. Sodium bicarbonate solution. (The concentration of calcium chloride solution should be 0.001~0.03 mol / L, and the concentration of sodium bicarbonate solution should be 0.1~3 mol / L.) Step two: Weigh the scale inhibitor to be evaluated, dilute it, and prepare a scale inhibitor solution. (The concentration of the scale inhibitor solution should be 0.3~10 mg / mL.) Step 3: Pour the sodium bicarbonate solution into the scale inhibitor solution storage tank 1 of the pharmaceutical storage system.

[0035] Step 4: Take a certain volume of calcium chloride solution V 1 and scale inhibitor solution V 3. Place the container in reaction tank 2, cover it, insert pH sensor 4, and seal the other holes.

[0036] Step 5: Start the drug storage system A, reaction system B, and power control and acquisition system D. Use a pump to continuously add sodium bicarbonate solution from scale inhibitor storage tank 1 to reaction tank 2. Switch the three-way valve 5. The mixed solution in reaction tank 2 flows from bottom to top through the outlet pipe and passes through pH sensor 4. Record and observe the changes in pH sensor 4 data. The pH shows a slow upward trend.

[0037] Step Six: When the pH value decreases (the pH value changes from rising to falling, showing an inflection point), the first stage of the experiment ends, and pH sensor 4 and the drug storage system are turned off. The maximum pH value before the pH decrease is recorded; that is, the set of pH values ​​before the pH decrease is the maximum pH, denoted as [value missing]. pH MAX The volume of sodium bicarbonate solution consumed at the maximum pH value is denoted as . V 2.

[0038] Step 7: Start the reaction system B, reverse osmosis membrane system C, and power control and acquisition system D, and switch the three-way valve 5. The mixed solution in reaction tank 2 passes through the reverse osmosis membrane 6 in the reverse osmosis membrane system, and the level recording cup 7 collects the volume of reverse osmosis permeate. V 4 and the corresponding reverse osmosis permeate consumption time t .

[0039] Step 8: Test several scale inhibitors to be used according to the above method, and calculate the calcium carbonate supersaturation S and the water production rate according to formulas (1) and (2). v And sort and evaluate them.

[0040] The higher the supersaturation value (S) of calcium carbonate, the better the performance of the scale inhibitor; water production rate v The larger the value, the better the performance of the scale inhibitor; calcium carbonate supersaturation (S) and permeate rate. v The performance of scale inhibitors was evaluated in a synergistic manner, with water production rate being one of the two key performance indicators. vThe weight of the supersaturation degree of calcium carbonate (S) is greater than that of the supersaturation degree of calcium carbonate (S). When the supersaturation degree of calcium carbonate (S) of a certain scale inhibitor is large, the water production rate is high. v The performance of a scale inhibitor can be evaluated based on the time it takes for the scale inhibitor to reach a certain level. When the supersaturation degree (S) of calcium carbonate in a certain scale inhibitor is small, the water production rate decreases. v When the scale inhibitor is large, its performance can be evaluated as defective.

[0041] In the performance evaluation of the scale inhibitor for the reverse osmosis system provided by this invention, the supersaturation of calcium carbonate (S value) and the permeate rate ( v The core synergistic indicator is the water production rate, which needs to be comprehensively judged in conjunction with the two indicators. v The core evaluation significance of scale inhibitors lies in assessing whether they cause organic fouling or other damage to the reverse osmosis membrane by monitoring their dynamic changes. The comprehensive performance of scale inhibitors must simultaneously meet the requirements of "strong scale inhibition" reflected by calcium carbonate supersaturation (S value) and permeate rate. v If the "low membrane fouling" requirement reflected in the standard is excellent in only one indicator while the other indicator is unbalanced, it can be determined that there is a performance defect.

[0042] For example, a certain scale inhibitor has a high calcium carbonate supersaturation (S value) but a low water production rate. v Low value: Although this type of scale inhibitor can effectively inhibit calcium carbonate precipitation, it may contain components that easily adsorb onto the membrane surface or react with organic matter in the water to generate fouling substances, leading to organic fouling or damage to the reverse osmosis membrane, manifested as a decrease in water production rate. v The performance of this type of scale inhibitor is limited. Although it meets the requirements for scale inhibition, it affects the system's water production efficiency due to membrane damage, thus having a performance shortcoming.

[0043] For example, a certain scale inhibitor may have a low calcium carbonate supersaturation (S) value but a low water production rate. v High value: Although this type of scale inhibitor does not cause significant fouling or damage to the reverse osmosis membrane, its core effectiveness in inhibiting calcium carbonate precipitation is insufficient, and it cannot effectively prevent calcium carbonate from depositing on the membrane surface to form hard scale. Long-term use will lead to aggravated membrane fouling, which will eventually cause a decrease in the permeate flow rate. Moreover, it violates the core functional positioning of the scale inhibitor and also has performance defects.

[0044] Example 1 This embodiment provides a method for evaluating the performance of reverse osmosis antiscalants, the specific steps of which are as follows: Step 1: Weigh 1.1098g of calcium chloride, dissolve it, and dilute to 1000mL to obtain a concentration of [missing value]. C I = 0.01 mol / L calcium chloride solution; Weigh 16.802 g of sodium bicarbonate, dissolve and dilute to 1000 mL, to obtain a concentration of C 2=0.2mol / L sodium bicarbonate solution.

[0045] Step 2: Weigh 1g of the scale inhibitor to be evaluated, dilute it, and bring the volume to 1000mL to prepare a scale inhibitor solution with a concentration of 1mg / mL.

[0046] Step 3: Pour the sodium bicarbonate solution into the scale inhibitor solution storage tank 1 of the pharmaceutical storage system.

[0047] Step 4: Take calcium chloride solution V 1 = 499.4 mL and scale inhibitor solution V Add 0.6 mL of pH 3 to reaction chamber 2, cover the chamber, insert pH sensor 4, and seal the other ports.

[0048] Step 5: Start the drug storage system A, reaction system B, and power control and acquisition system D. Use a pump to continuously add sodium bicarbonate solution from scale inhibitor storage tank 1 to reaction tank 2. Switch the three-way valve 5. The mixed solution in reaction tank 2 flows from bottom to top through the outlet pipe and passes through pH sensor 4. Record and observe the changes in pH sensor 4 data. The pH shows a slow upward trend.

[0049] Step Six: When the pH value decreases (the pH value changes from rising to falling, showing an inflection point), the first stage of the experiment ends, and pH sensor 4 and the drug storage system are turned off. The maximum pH value before the pH decrease is recorded; that is, the set of pH values ​​before the pH decrease is the maximum pH, denoted as [value missing]. pH MAX =8.08, at the maximum pH value, the volume of sodium bicarbonate solution consumed is recorded as . V 2 = 98 mL.

[0050] Step 7: Start the reaction system B, reverse osmosis membrane system C, and power control and acquisition system D, and switch the three-way valve 5. The mixed solution in reaction tank 2 passes through the reverse osmosis membrane 6 in the reverse osmosis membrane system, and the level recording cup 7 collects the volume of reverse osmosis permeate. V 4 = 300mL and corresponding reverse osmosis permeate consumption time t =150s.

[0051] Step 8: According to formulas (1) and (2), the supersaturation degree of calcium carbonate S1 of scale inhibitor No. 1 is 320.67; water production rate v 1 = 2 mL / s.

[0052] Example 2 This embodiment provides a method for evaluating the performance of reverse osmosis antiscalants, the specific steps of which are as follows: Step 1: Weigh 0.8879 g of calcium chloride, dissolve it, and dilute to 1000 mL to obtain a concentration of [missing value]. CI = 0.008 mol / L calcium chloride solution; Weigh 21.0025 g of sodium bicarbonate, dissolve and dilute to 1000 mL, to obtain a concentration of C 2=0.25mol / L sodium bicarbonate solution.

[0053] Step 2: Weigh 1g of the scale inhibitor No. 2 to be evaluated, dilute it, and make up to 1000mL to prepare a scale inhibitor solution with a concentration of 1mg / mL.

[0054] Step 3: Pour the sodium bicarbonate solution into the scale inhibitor solution storage tank 1 of the pharmaceutical storage system.

[0055] Step 4: Take calcium chloride solution V 1=399.6mL and scale inhibitor solution V Add 0.4 mL of solution to reaction vessel 2, cover the vessel, insert pH sensor 4, and seal the other ports.

[0056] Step 5: Start the drug storage system A, reaction system B, and power control and acquisition system D. Use a pump to continuously add sodium bicarbonate solution from scale inhibitor storage tank 1 to reaction tank 2. Switch the three-way valve 5. The mixed solution in reaction tank 2 flows from bottom to top through the outlet pipe and passes through pH sensor 4. Record and observe the changes in pH sensor 4 data. The pH shows a slow upward trend.

[0057] Step Six: When the pH value decreases (the pH value changes from rising to falling, showing an inflection point), the first stage of the experiment ends, and pH sensor 4 and the drug storage system are turned off. The maximum pH value before the pH decrease is recorded; that is, the set of pH values ​​before the pH decrease is the maximum pH, denoted as [value missing]. pH MAX =8.15, at the maximum pH value, the volume of sodium bicarbonate solution consumed is recorded as . V 2 = 105 mL.

[0058] Step 7: Start the reaction system B, reverse osmosis membrane system C, and power control and acquisition system D, and switch the three-way valve 5. The mixed solution in reaction tank 2 passes through the reverse osmosis membrane 6 in the reverse osmosis membrane system, and the level recording cup 7 collects the volume of reverse osmosis permeate. V 4= 28 0 mL and corresponding reverse osmosis permeate consumption time t =110s.

[0059] Step 8: Calculate according to formulas (1) and (2), the supersaturation degree of calcium carbonate S2 of scale inhibitor No. 2 is 452; water production rate. v 2 = 2.54 mL / s.

[0060] Example 3 This embodiment provides a method for evaluating the performance of reverse osmosis antiscalants, the specific steps of which are as follows: Step 1: Weigh 2.5525g of calcium chloride, dissolve it, and dilute to 1000mL to obtain a concentration of [missing value]. C A calcium chloride solution with a concentration of 1 = 0.023 mol / L was prepared. 147.0175 g of sodium bicarbonate was weighed, dissolved, and diluted to 1000 mL to obtain a solution with a concentration of [missing value]. C 2 = 1.75 mol / L sodium bicarbonate solution.

[0061] Step 2: Weigh 1g of the scale inhibitor No. 3 to be evaluated, dilute it, and make up to 1000mL to prepare a scale inhibitor solution with a concentration of 1mg / mL.

[0062] Step 3: Pour the sodium bicarbonate solution into the scale inhibitor solution storage tank 1 of the pharmaceutical storage system.

[0063] Step 4: Take calcium chloride solution V 1 = 800 mL and scale inhibitor solution V Add 1 mL of solution to reaction vessel 2, cover the vessel, insert pH sensor 4, and seal the other ports.

[0064] Step 5: Start the drug storage system A, reaction system B, and power control and acquisition system D. Use a pump to continuously add sodium bicarbonate solution from scale inhibitor storage tank 1 to reaction tank 2. Switch the three-way valve 5. The mixed solution in reaction tank 2 flows from bottom to top through the outlet pipe and passes through pH sensor 4. Record and observe the changes in pH sensor 4 data. The pH shows a slow upward trend.

[0065] Step Six: When the pH value decreases (the pH value changes from rising to falling, showing an inflection point), the first stage of the experiment ends, and pH sensor 4 and the drug storage system are turned off. The maximum pH value before the pH decrease is recorded; that is, the set of pH values ​​before the pH decrease is the maximum pH, denoted as [value missing]. pH MAX =8.02, at the maximum pH value, the volume of sodium bicarbonate solution consumed is recorded as . V 2 = 15 mL.

[0066] Step 7: Start the reaction system B, reverse osmosis membrane system C, and power control and acquisition system D, and switch the three-way valve 5. The mixed solution in reaction tank 2 passes through the reverse osmosis membrane 6 in the reverse osmosis membrane system, and the level recording cup 7 collects the volume of reverse osmosis permeate. V 4= 30 0 mL and corresponding reverse osmosis permeate consumption time t =115s.

[0067] Step 8: According to formulas (1) and (2), the supersaturation degree of calcium carbonate S3 of scale inhibitor No. 3 is 740; water production rate.v 3 = 2.61 mL / s.

[0068] In summary, three scale inhibitors, S1 < S2 < S3, are proposed to be selected. v 1 < v 2< v 3 ，3 The scale inhibitor No. 1 has the best performance.

[0069] Example 4 This embodiment provides a method for evaluating the performance of reverse osmosis antiscalants, the specific steps of which are as follows: Step 1: Weigh 0.9899g of calcium chloride, dissolve it, and dilute to 1000mL to obtain a concentration of [missing value]. C I = 0.009 mol / L calcium chloride solution; Weigh 20.4521 g of sodium bicarbonate, dissolve and dilute to 1000 mL, to obtain a concentration of C 2=0.21mol / L sodium bicarbonate solution.

[0070] Step 2: Weigh 1g of the scale inhibitor No. 4 to be evaluated, dilute it, and bring the volume to 1000mL to prepare a scale inhibitor solution with a concentration of 1mg / mL.

[0071] Step 3: Pour the sodium bicarbonate solution into the scale inhibitor solution storage tank 1 of the pharmaceutical storage system.

[0072] Step 4: Take calcium chloride solution V 1=399.6mL and scale inhibitor solution V Add 0.4 mL of solution to reaction vessel 2, cover the vessel, insert pH sensor 4, and seal the other ports.

[0073] Step 5: Start the drug storage system A, reaction system B, and power control and acquisition system D. Use a pump to continuously add sodium bicarbonate solution from scale inhibitor storage tank 1 to reaction tank 2. Switch the three-way valve 5. The mixed solution in reaction tank 2 flows from bottom to top through the outlet pipe and passes through pH sensor 4. Record and observe the changes in pH sensor 4 data. The pH shows a slow upward trend.

[0074] Step Six: When the pH value decreases (the pH value changes from rising to falling, showing an inflection point), the first stage of the experiment ends, and pH sensor 4 and the drug storage system are turned off. The maximum pH value before the pH decrease is recorded; that is, the set of pH values ​​before the pH decrease is the maximum pH, denoted as [value missing]. pH MAX =8.17, at the maximum pH value, the volume of sodium bicarbonate solution consumed is denoted as . V 2 = 108 mL.

[0075] Step 7: Start the reaction system B, reverse osmosis membrane system C, and power control and acquisition system D, and switch the three-way valve 5. The mixed solution in reaction tank 2 passes through the reverse osmosis membrane 6 in the reverse osmosis membrane system, and the level recording cup 7 collects the volume of reverse osmosis permeate. V 4 = 400 mL and the corresponding reverse osmosis permeate consumption time t =195s.

[0076] Step 8: According to formulas (1) and (2), the supersaturation degree of calcium carbonate S4 of scale inhibitor No. 4 is 455; water production rate. v 4 = 2.05 mL / s.

[0077] In summary, three scale inhibitors are proposed: S1 < S2 < S4. v 1 < v 4< v 2. Although the supersaturation of calcium carbonate was the highest when sample 4 was added, and the effect of inhibiting scaling and precipitation was the best (slightly better than sample 2), the reverse osmosis permeate rate was worse than that of sample 2. It is suspected that the products generated by the reaction may produce colloids and pose a risk of fouling and clogging to the membrane elements. Therefore, sample 2 was selected.

[0078] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. An apparatus suitable for performance evaluation of reverse osmosis scale inhibitors, characterized in that, The power control collection system is electrically connected with the medicine storage system, the reaction generation system and the reverse osmosis membrane system. The connecting pipeline between the medicine storage system and the reaction generation system extends into the reaction pool (2), the stirring rod (3) is arranged inside the reaction pool (2), the pH sensor (4) is arranged outside the reaction pool (2), the bottom of the pool wall on one side of the reaction pool (2) is penetrated to be connected with the outflow pipeline, the outflow pipeline is connected with the inlet of the pH sensor (4) and the inlet of the reverse osmosis membrane (6) through the three-way valve (5), and the outlet of the pH sensor (4) extends into the reaction pool (2) through the top cover of the reaction pool (2).

2. The device suitable for performance evaluation of reverse osmosis scale inhibitors according to claim 1, characterized in that, The reaction pool (2) is a double-layer transparent glass pool, which is composed of an inner transparent glass pool and an outer transparent glass pool, and a sandwich layer is arranged between the inner transparent glass pool and the outer transparent glass pool, a water inlet is arranged on the lower part of one side of the outer transparent glass pool, and a water outlet is arranged on the upper part of the opposite side.

3. The device suitable for performance evaluation of reverse osmosis scale inhibitors according to claim 1, characterized in that, The reaction pool (2) includes a double-layer transparent glass pool body and a cover arranged above the double-layer transparent glass pool body, the double-layer transparent glass pool body and the cover are threadedly connected, and an elastic sealing gasket is arranged between the double-layer transparent glass pool body and the cover.

4. The device suitable for performance evaluation of reverse osmosis scale inhibitors according to claim 3, characterized in that, The cover is penetrated with a first opening, a second opening, a third opening and at least one selectively openable or blockable through hole, the connecting pipeline between the medicine storage system and the reaction generation system extends into the reaction pool (2) through the first opening, the stirring rod (3) is arranged in the reaction pool (2) through the second opening, and the outlet of the pH sensor (4) extends into the reaction pool (2) through the third opening.

5. The device suitable for performance evaluation of reverse osmosis scale inhibitors according to claim 1, characterized in that, The reverse osmosis membrane system further includes a liquid level cup (7) arranged directly below the outlet of the reverse osmosis membrane (6). The power control collection system is electrically connected with the stirring rod (3), the pH sensor (4), the three-way valve (5), the pump on the connecting pipeline between the medicine storage system and the reaction generation system, the pump on the outflow pipeline between the reaction pool (2) and the three-way valve (5), and the pump on the connecting pipeline between the three-way valve (5) and the inlet of the reverse osmosis membrane (6).

6. A method for evaluating the performance of a reverse osmosis scale inhibitor characterized in that, The device suitable for reverse osmosis scale inhibitor performance evaluation based on any one of claims 1 to 5 comprises the following steps: S1: preparing calcium chloride solution and sodium bicarbonate solution; diluting the scale inhibitor solution to be evaluated to prepare a scale inhibitor solution; loading the sodium bicarbonate solution into the medicine storage system, adding the calcium chloride solution and the scale inhibitor solution into the reaction pool (2), assembling the stirring rod (3), and inserting the pH sensor (4); S2: open the drug storage system and reaction system, power control acquisition system, pumping sodium bicarbonate solution in the drug storage system is continuously added to the reaction tank (2), switching three-way valve (5), the mixed solution in the reaction tank (2) passes through the pH sensor (4) from bottom to top, and the data change of the pH sensor (4) is recorded in real time, when the pH value presents a change inflection point from rising to falling, the test is stopped, the pH sensor (4) and the drug storage system are closed, the maximum pH value before the pH reduction and the corresponding sodium bicarbonate solution consumption volume when the maximum pH value are recorded, and the calcium carbonate supersaturation is calculated; S3: open the reaction system and reverse osmosis membrane system, power control acquisition system, switch three-way valve (5), the mixed solution in the reaction tank (2) flows through the reverse osmosis membrane (6), the reverse osmosis water production volume and the corresponding reverse osmosis water consumption time are recorded, and the water production rate is calculated; S4: according to the calcium carbonate supersaturation and the water production rate, the performance of the reverse osmosis scale inhibitor is sorted and evaluated.

7. The method for evaluating the performance of reverse osmosis scale inhibitors according to claim 6, characterized in that, The calculation formula of the calcium carbonate supersaturation is as follows: In the above formula, S is the calcium carbonate supersaturation; C 1 is the concentration of calcium chloride solution, unit: mol / L; C 2 is the concentration of sodium bicarbonate solution, unit: mol / L; V 1 is the volume of calcium chloride solution, unit: mL; V 2 is the volume of sodium bicarbonate solution consumed corresponding to the maximum pH value, unit: mL; V 3 is the volume of scale inhibitor solution, unit: mL; pH is the maximum pH value.

8. The method for evaluating the performance of reverse osmosis scale inhibitors according to claim 6, characterized in that, The calculation formula of the water production rate is as follows: In the above formula, v is the water production rate, in L / h; V 4 is the reverse osmosis water production volume, in L; t is the reverse osmosis water production time, in h.

9. The method for evaluating the performance of reverse osmosis scale inhibitors according to claim 6, characterized in that, The calcium carbonate supersaturation is positively correlated with the performance of the reverse osmosis scale inhibitor, and the water production rate is positively correlated with the performance of the reverse osmosis scale inhibitor.

10. The method for evaluating the performance of reverse osmosis scale inhibitors according to claim 6, characterized in that, The concentration of the calcium chloride solution is 0.001-0.03 mol / L, the concentration of the sodium bicarbonate solution is 0.1-3 mol / L, and the concentration of the scale inhibitor solution is 0.3-10 mg / mL.

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