Antiscalant for RO membrane used in high-salinity wastewater recovery and preparation method thereof

Abstract

The application discloses a scale inhibitor for a high-salt wastewater recovery RO membrane and a preparation method thereof, and relates to the technical field of water treatment agents. 2+ The calcium tolerance of the scale inhibitor is higher than 820 mg / L in a solution with a concentration of 2000 mg / L. The scale inhibitor prepared by the application has a high scale inhibition rate on calcium sulfate and calcium fluoride, and has excellent silicon resistance, aluminum resistance and iron oxide dispersion performance when used in the high-salt wastewater recovery RO membrane.

Description

Technical Field

[0001] This invention relates to the field of water treatment reagents technology; specifically, it relates to a scale inhibitor for RO membrane recovery of high-salinity wastewater and its preparation method. Background Technology

[0002] With the depletion of freshwater resources, many researchers have focused on greywater recycling and seawater desalination. To desalinate landfill leachate, coal chemical wastewater, papermaking wastewater, dyeing and printing wastewater, and seawater, many regions employ a combination of physicochemical, biological, and advanced treatment methods to achieve wastewater recycling or discharge. Ultrafiltration, nanofiltration, and reverse osmosis are commonly used for advanced treatment. However, when the influent salinity is too high, it can easily cause fouling of the reverse osmosis membrane, reducing flux, lowering water recovery efficiency, and increasing the frequency of membrane cleaning.

[0003] Currently, commercially available reverse osmosis antiscalants work by occupying certain positions on inorganic salt crystal nuclei or microcrystals with some functional groups, hindering and disrupting the growth of inorganic salt crystals, slowing down the crystal growth rate, and thus reducing scale formation. They have good scale inhibition effects for ordinary water quality. However, for some high-salt, complex greywater reuse systems, conventional antiscalants are insufficient to ensure stable system operation and prevent the precipitation of certain inorganic scale. Therefore, a membrane antiscalant suitable for high-salinity reverse osmosis membrane systems is needed. Summary of the Invention

[0004] The purpose of this invention is to provide a scale inhibitor with a high scale inhibition rate for calcium sulfate and calcium fluoride. When used in RO membranes for high-salt wastewater recovery, it exhibits excellent silicon and aluminum inhibition properties, and also has excellent dispersibility for iron oxide.

[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0006] A scale inhibitor, comprising: component a and component b;

[0007] The weight ratio of component a to component b is 2-10:5-20.

[0008] Component a above includes at least a copolymer of acrylic acid and maleic anhydride;

[0009] The above scale inhibitors in Ca 2+ In a solution with a concentration of 2000 mg / L, the calcium tolerance is higher than 820 mg / L.

[0010] This invention prepares a scale inhibitor by compounding components a and b, which has a high calcium tolerance. Simultaneously, the scale inhibitor exhibits a high scale inhibition rate for calcium sulfate and calcium fluoride. When used in high-salt wastewater in reverse osmosis membranes, the scale inhibitor demonstrates excellent silicon and aluminum inhibition properties, preventing silicates and aluminum hydroxide colloids from forming fouling on the reverse osmosis membrane, thus achieving good scale inhibition performance. Furthermore, it has excellent dispersibility for iron oxide, allowing it to remain suspended in water and preventing precipitation on the reverse osmosis membrane.

[0011] Preferably, in an embodiment of the invention, component b comprises at least one of an organophosphonic acid and a copolymer.

[0012] More preferably, in embodiments of the present invention, the organophosphorus comprises at least one of diethylenetriaminepentamethylenephosphonic acid, aminotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylenephosphonic acid, and 2-hydroxyphosphonoacetic acid.

[0013] More preferably, in embodiments of the present invention, the copolymer includes at least one of polyepoxysuccinic acid, ammonium polyacrylate, AA / AMPS binary copolymer, and phosphine-based polycarboxylic acid copolymer.

[0014] More preferably, in an embodiment of the present invention, component b comprises diethylenetriaminepentamethylphosphonic acid and polyepoxysuccinic acid.

[0015] More preferably, in an embodiment of the present invention, the weight ratio of diethylenetriaminepentamethylphosphonic acid to polyepoxysuccinic acid in component b is 2-7:1-5.

[0016] This invention also discloses the use of a scale inhibitor in RO membranes for high-salt wastewater recovery.

[0017] Preferably, the dosage of scale inhibitor in high-salt wastewater is 10-80 mg / L.

[0018] The present invention also discloses a method for preparing a scale inhibitor, wherein component a and component b are mixed evenly with water to obtain a scale inhibitor.

[0019] This invention provides a scale inhibitor prepared by compounding components a and b, which exhibits high calcium tolerance. Simultaneously, this scale inhibitor demonstrates high scale inhibition rates for calcium sulfate and calcium fluoride. When applied to high-salt wastewater in reverse osmosis membranes, it exhibits excellent silica and aluminum inhibition properties, preventing silicates and aluminum hydroxide colloids from forming fouling on the reverse osmosis membrane, thus achieving good scale inhibition performance. Furthermore, it possesses excellent dispersibility for iron oxide, allowing it to remain suspended in water and preventing precipitation on the reverse osmosis membrane. Therefore, this invention provides a scale inhibitor with high scale inhibition rates for calcium sulfate and calcium fluoride. When used in RO membranes for high-salt wastewater recovery, it demonstrates excellent silica and aluminum inhibition properties, and also exhibits excellent dispersibility for iron oxide. Attached Figure Description

[0020] Figure 1 The infrared spectrum of the lignin derivative in Example 4;

[0021] Figure 2 Calcium tolerance of scale inhibitors used in RO membranes for high-salinity wastewater recovery;

[0022] Figure 3 The scale inhibition rate of the scale inhibitor on calcium sulfate;

[0023] Figure 4 The scale inhibition rate of the scale inhibitor on calcium fluoride;

[0024] Figure 5 This refers to the dispersing properties of scale inhibitors on iron oxide. Detailed Implementation

[0025] The present invention will now be described in detail with reference to specific embodiments. The following embodiments and comparative examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. Any improvements made by those skilled in the art without departing from the concept of the present invention are within the scope of protection of the present invention.

[0026] The scale inhibitor of the present invention comprises component a and component b, and the weight ratio of component a to component b is 2-10:5-20; wherein component a comprises a copolymer of acrylic acid and maleic anhydride; component b comprises diethylenetriamine pentamethylphosphonic acid and polyepoxysuccinic acid, and the weight ratio of diethylenetriamine pentamethylphosphonic acid to polyepoxysuccinic acid is 2-7:1-5.

[0027] Specifically, the preparation method of the scale inhibitor in this invention is as follows: Component a and component b are placed in a container at a weight ratio of 2-10:5-20, and 4-6 times the amount of water of component a is added. The mixture is stirred and mixed evenly. Component a includes a copolymer of acrylic acid and maleic anhydride; component b includes diethylenetriaminepentamethylenephosphonic acid and polyepoxysuccinic acid, and the weight ratio of diethylenetriaminepentamethylenephosphonic acid to polyepoxysuccinic acid is 2-7:1-5, thereby obtaining the scale inhibitor.

[0028] Preferably, the scale inhibitor of the present invention further includes a lignin derivative, wherein the lignin derivative is obtained by oxidation and pyridinol esterification of lignin; the scale inhibitor is prepared by compounding it with other components of the scale inhibitor, which further improves the dispersibility of the scale inhibitor on iron oxide and its scale inhibition performance.

[0029] More preferably, the amount of lignin derivative added is 20-40 wt% of component a; specifically preferably 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%.

[0030] More preferably, the method for preparing the lignin derivative in this invention includes:

[0031] Lignin was provided, and distilled water was added to the lignin in a container. The mixture was dissolved in a water bath at 30-35°C, and then sodium hypochlorite was added. The mixture was mechanically stirred for 20-30 minutes, cooled to room temperature, and the pH was adjusted to 2-3 with a 2-4 mol / L hydrochloric acid solution. The mixture was then centrifuged, washed, and dried to obtain lignin polyacids with a yield of 62.7-65.4% and an acid content of 9.6-10.8%.

[0032] The method for determining the carboxyl group content of lignin polyacids in this invention is as follows:

[0033] Take 250 mg of lignin polyacid sample and place it in a round-bottom flask. Add 30 mL of 0.5 mol / L calcium acetate solution and incubate at 80 °C for 30 min. Cool to room temperature, filter, and transfer the filtrate to a 50 mL volumetric flask. Add distilled water to the mark. Then, take 15 mL of the filtrate and add it to 20 mL of distilled water. Using phenolphthalein as an indicator, titrate with a 0.1 mol / L standard solution. Perform a blank experiment simultaneously. The formula for calculating the carboxyl content (A) is as follows:

[0034] A=(V1-V0)×c×5×45.02 / m×100%

[0035] In the formula: V1 is the volume of sodium hydroxide standard solution consumed by the sample, mL; V0 is the volume of sodium hydroxide standard solution consumed by the blank, mL; c is the concentration of sodium hydroxide standard solution, mol / L; m is the mass of the sample added, mg; 45.02 is the molar mass of the carboxyl group, g / mol; 5 is the conversion factor, 50mL / 10mL.

[0036] The lignin polyacid was placed in a container, and DMAP, DMF and pyridinol were added. The mixture was then magnetically stirred for 20-30 minutes in a water bath at 40-60℃. EDC and DMF were then added and the mixture was magnetically stirred for 2-4 hours. The mixture was then rotary evaporated, centrifuged, washed, dried and ground to obtain the lignin derivative.

[0037] More preferably, in the method for preparing lignin derivatives, the ratio of sodium hypochlorite to lignin is 10-15 mmol:1g.

[0038] More preferably, in the method for preparing lignin derivatives, the raw materials are in the following weight parts: 2-4 parts of lignin polyacid, 0.03-0.06 parts of DMAP, 140-180 parts of DMF, 2-5 parts of pyridinol, and 0.5-1.5 parts of EDC.

[0039] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings:

[0040] Example 1: A method for preparing a scale inhibitor for RO membrane recovery of high-salinity wastewater is as follows:

[0041] Component a and component b were placed in a beaker at a weight ratio of 5:16, and 5 times the amount of water of component a was added. The mixture was stirred and mixed evenly. Component a is a copolymer of acrylic acid and maleic anhydride (CAS No.: 26677-99-6); component b includes diethylenetriamine pentamethylphosphonic acid and polyepoxysuccinic acid (CAS No.: 51274-37-4), and the weight ratio of diethylenetriamine pentamethylphosphonic acid to polyepoxysuccinic acid is 2:5, thus obtaining a scale inhibitor.

[0042] Example 2: A method for preparing a scale inhibitor for RO membrane recovery of high-salinity wastewater, which differs from Example 1 in that:

[0043] Component a and component b are placed in a beaker at a weight ratio of 3:20. Six times the amount of water as component a is added and the mixture is stirred until homogeneous. Component b includes diethylenetriamine pentamethylphosphonic acid and polyepoxysuccinic acid (CAS No.: 51274-37-4). The weight ratio of diethylenetriamine pentamethylphosphonic acid to polyepoxysuccinic acid is 7:2, thus obtaining a scale inhibitor.

[0044] Example 3: A method for preparing a scale inhibitor for RO membrane recovery of high-salinity wastewater, which differs from Example 1 in that:

[0045] Component a and component b are placed in a beaker at a weight ratio of 10:20. Add 4 times the amount of water of component a and stir to mix evenly. Component b includes diethylenetriaminepentimidephosphonic acid and polyepoxysuccinic acid (CAS No.: 51274-37-4). The weight ratio of diethylenetriaminepentimidephosphonic acid to polyepoxysuccinic acid is 6:1, thus obtaining a scale inhibitor.

[0046] Example 4: A method for preparing a scale inhibitor for RO membrane recovery of high-salinity wastewater, which differs from Example 1 in that:

[0047] Component a and component b were placed in a beaker at a weight ratio of 5:16. 20 wt% of the lignin derivative of component a and 5 times the amount of water of component a were added and stirred until homogeneous. Component a is a copolymer of acrylic acid and maleic anhydride (CAS No.: 26677-99-6); component b includes diethylenetriamine pentamethylphosphonic acid and polyepoxysuccinic acid (CAS No.: 51274-37-4), with a weight ratio of diethylenetriamine pentamethylphosphonic acid to polyepoxysuccinic acid of 2:5, to obtain a scale inhibitor.

[0048] The method for preparing the lignin derivative in this embodiment includes:

[0049] Lignin (content ≥90%) was provided. 10 parts by weight of lignin were placed in a flask and 320 parts by weight of distilled water were added. The mixture was dissolved in a water bath at 32°C. Then, sodium hypochlorite was added, with a sodium hypochlorite to lignin ratio of 10 mmol:1 g. The mixture was mechanically stirred for 25 min. After the reaction was completed, the mixture was cooled to room temperature and the pH was adjusted to 2.5 with a 3 mol / L hydrochloric acid solution. The mixture was centrifuged and washed three times with distilled water. It was then dried at 60°C for 5 h to obtain lignin polyacids with a yield of 63.9% and an acid content of 10.2%.

[0050] Three parts by weight of lignin polyacid were placed in a container, and 0.04 parts by weight of DMAP, 110 parts by weight of DMF and 2 parts by weight of pyridinol were added. The mixture was then magnetically stirred for 30 min in a water bath at 50 °C. Then, 1.2 parts by weight of EDC and 40 parts by weight of DMF were added and magnetically stirred for 3 h. The solvent was removed by rotary evaporation, centrifugation was performed, and the mixture was washed three times with distilled water. The mixture was then dried at 60 °C for 10 h and ground to obtain the lignin derivative.

[0051] Example 5: A method for preparing a scale inhibitor for RO membrane recovery of high-salinity wastewater, which differs from Example 1 in that:

[0052] The amount of lignin derivative added to the scale inhibitor is 30 wt% of component a.

[0053] The preparation method of the lignin derivative is the same as that in Example 4.

[0054] Example 6: A method for preparing a scale inhibitor for RO membrane recovery of high-salinity wastewater, which differs from Example 1 in that:

[0055] The optimized implementation scheme of the scale inhibitor of the present invention further includes adding 5-10 wt% of asparagine methyl ester of component a to the scale inhibitor, which further improves the scale inhibition performance. When used in RO membranes for high-salt wastewater recovery, it has excellent scale inhibition performance against silicates and aluminum ions, and at the same time has good dispersibility for iron oxide.

[0056] Component a and component b were placed in a beaker at a weight ratio of 5:16. 5 wt% of asparagine methyl ester of component a and 5 times the amount of water of component a were added and stirred until homogeneous. Component a is a copolymer of acrylic acid and maleic anhydride (CAS No.: 26677-99-6); component b includes diethylenetriamine pentamethylphosphonic acid and polyepoxysuccinic acid (CAS No.: 51274-37-4), with a weight ratio of diethylenetriamine pentamethylphosphonic acid to polyepoxysuccinic acid of 2:5, to obtain a scale inhibitor.

[0057] Example 7: A method for preparing a scale inhibitor for RO membrane recovery of high-salinity wastewater, which differs from Example 1 in that:

[0058] The amount of asparagine methyl ester added to the scale inhibitor is 10 wt% of component a.

[0059] Example 8: A method for preparing a scale inhibitor for RO membrane recovery of high-salinity wastewater, which differs from Example 1 in that:

[0060] Component a and component b were placed in a beaker at a weight ratio of 5:16. 20 wt% of lignin derivative of component a, 5 wt% of asparagine methyl ester of component a, and 5 times the amount of water of component a were added and stirred until homogeneous. Component a is a copolymer of acrylic acid and maleic anhydride (CAS No.: 26677-99-6); component b includes diethylenetriamine pentamethylphosphonic acid and polyepoxysuccinic acid (CAS No.: 51274-37-4), with a weight ratio of diethylenetriamine pentamethylphosphonic acid to polyepoxysuccinic acid of 2:5, to obtain a scale inhibitor.

[0061] The preparation method of the lignin derivative is the same as that in Example 4.

[0062] Example 9, Performance Testing

[0063] 1. Infrared spectroscopy test

[0064] Fourier transform infrared spectroscopy was used to determine the infrared spectra of lignin derivatives, with a test range of 4000-500 cm⁻¹. -1 .

[0065] Figure 1 The image shows the infrared spectrum of the lignin derivative in Example 4; curves a and b represent the lignin polyacid and the lignin derivative, respectively; [The image is from...] Figure 1 It can be seen that, compared to lignin polyacids, lignin derivatives at 3005 cm⁻¹ -1 The characteristic absorption peak appearing nearby is due to the stretching vibration of the pyridine ring; at 2920 cm⁻¹ -1 The characteristic absorption peaks of alkyl groups appearing nearby are significantly enhanced; 1730 cm⁻¹ -1 The characteristic absorption peak appearing nearby is due to the stretching vibration of the ester group; 1590 cm⁻¹ -1 The characteristic absorption peaks that appear nearby are due to the stretching vibration of C=C; thus, it can be concluded that lignin derivatives are obtained by oxidation and pyridinol esterification of lignin.

[0066] 2. Scale inhibitor performance test

[0067] (1) Calcium tolerance test

[0068] Add calcium chloride standard solution to a volumetric flask to make the calcium ion concentration 2000 mg / L. Add borax buffer solution to adjust the pH to 9.0. Then pour the solution into an Erlenmeyer flask, dilute to volume with distilled water, and shake well. Under magnetic stirring, adjust the water bath temperature to 50°C and add scale inhibitor dropwise. When precipitation occurs, record the amount of scale inhibitor consumed, which is the calcium tolerance of the scale inhibitor. Use commercially available PAA scale inhibitor as a control group.

[0069] Figure 2 The calcium tolerance of the scale inhibitor used in RO membranes for high-salinity wastewater recovery; by Figure 2 It can be seen that the calcium tolerance of the scale inhibitors in Examples 1-3 is higher than 820 mg / L, which is higher than that of the control group, indicating that the scale inhibitor prepared by the present invention has a high calcium tolerance, which is superior to commercially available PAA scale inhibitors. The calcium tolerance of the scale inhibitors in Examples 4-5 is higher than 1100 mg / L, which is higher than that of Example 1, indicating that the addition of lignin derivatives obtained by oxidation and pyridinol esterification of lignin to the scale inhibitor improves the calcium tolerance of the scale inhibitor, makes the performance of the scale inhibitor more stable, and thus improves the scale inhibition effect. The calcium tolerance of the scale inhibitor in Example 8 is higher than 1120 mg / L, which is higher than that of Examples 1 and 4, indicating that the simultaneous addition of lignin derivatives and aspartic phenylalanine methyl ester to the scale inhibitor further improves the calcium tolerance of the scale inhibitor.

[0070] (2) Scale inhibition performance test

[0071] ① Scale inhibition performance of calcium sulfate

[0072] Experimental conditions: Preparation of a solution containing specific Ca 2+ (2500mg / L), SO4 2- Experimental water with a concentration of 3000 mg / L (calculated as sodium sulfate) was treated with 15 mg / L scale inhibitor, pH 7.0, and constant temperature of 60℃ for 8 hours. The experimental water was then filtered, and the calcium ion concentration of the filtrate was determined by direct titration with EDTA. Experimental water without scale inhibitor was used as a blank control. The scale inhibition rate was calculated using the following formula:

[0073] B = (C2 - C1) / (C3 - C1) × 100%

[0074] In the formula: C1 is the calcium ion concentration of the blank experimental water without scale inhibitor after the experiment, mg / mL; C2 is the calcium ion concentration of the experimental water with scale inhibitor after the experiment, mg / mL; C3 is the calcium ion concentration of the experimental water prepared before the experiment, mg / mL.

[0075] Figure 3 The scale inhibition rate of the scale inhibitor on calcium sulfate; by Figure 3It can be seen that the scale inhibitors in Examples 1-3 have a scale inhibition rate of over 81% for calcium sulfate, indicating that the scale inhibitors prepared in this invention have a high scale inhibition rate for calcium sulfate. The scale inhibitors in Examples 4-5 have a scale inhibition rate of over 85% for calcium sulfate, which is higher than that in Example 1, indicating that the addition of lignin derivatives obtained by oxidation and pyridinol esterification of lignin to the scale inhibitors improves the scale inhibition rate for calcium sulfate. The scale inhibitors in Examples 6-7 have a scale inhibition rate of over 83% for calcium sulfate, and the scale inhibitors in Example 8 have a scale inhibition rate of over 89% for calcium sulfate. The calcium sulfate scale inhibition rate in Examples 6-7 is higher than that in Example 1, and the calcium sulfate scale inhibition rate in Example 8 is higher than that in Example 4, indicating that the addition of lignin derivatives and asparagine methyl ester to the scale inhibitors further improves the scale inhibition rate for calcium sulfate.

[0076] ② Scale inhibition performance of calcium fluoride

[0077] Experimental conditions: Contains Ca 2+ 2000 mg / L, F - Using experimental water at a concentration of 5000 mg / L, and with other experimental conditions identical to those for "scale inhibition performance of calcium sulfate", calculate the scale inhibition performance of calcium fluoride.

[0078] Figure 4 The scale inhibition rate of the scale inhibitor on calcium fluoride; by Figure 4 It can be seen that the scale inhibitors in Examples 1-3 exhibited a scale inhibition rate of over 73% for calcium fluoride, indicating that the scale inhibitors prepared in this invention have a high scale inhibition rate for calcium fluoride. In Examples 4-5, the scale inhibitors exhibited a scale inhibition rate of over 79% for calcium fluoride, which is higher than that in Example 1, indicating that the addition of lignin derivatives obtained by oxidation and pyridinol esterification of lignin to the scale inhibitor improved the scale inhibition rate for calcium fluoride. In Examples 6-7, the scale inhibitors exhibited a scale inhibition rate of over 77% for calcium fluoride, and in Example 8, the scale inhibitors exhibited a scale inhibition rate of over 83% for calcium fluoride. The scale inhibition rates of calcium fluoride in Examples 6-7 were higher than those in Example 1, and those in Example 8 were higher than those in Example 4, indicating that the addition of lignin derivatives and asparagine methyl ester to the scale inhibitor further improved the scale inhibition rate for calcium fluoride.

[0079] ③ Dispersion properties of ferric oxide

[0080] Add calcium chloride solution (Ca) to the volumetric flask 2+ The concentration was 50 mg / L, then 30 mg / L of scale inhibitor was added, the pH was adjusted to 9.0 using borax buffer solution, and then ferric sulfate solution (Fe) was added under stirring. 2+The solution (concentration 15 mg / L) was diluted to volume with deionized water and stirred for 20 min. It was then allowed to stand in a constant temperature water bath at 55℃ for 6 h. After maintaining the constant temperature, the supernatant was collected, and its transmittance at 420 nm was measured using a spectrophotometer. Distilled water was used as a blank control to ensure 100% transmittance. A lower transmittance indicates a higher concentration of suspended iron oxide in the water and better dispersion performance of the iron oxide.

[0081] Figure 5 The dispersing properties of scale inhibitors on iron oxide; by Figure 5 It can be seen that the transmittance of iron oxide in Examples 1-3 is less than 54%, indicating that the scale inhibitor prepared by the present invention has excellent dispersing effect on iron oxide, enabling iron oxide to be suspended in water without precipitation; the transmittance of iron oxide in Examples 6-7 is less than 51%, and the transmittance of iron oxide in Example 8 is less than 50%, wherein the transmittance of iron oxide in Examples 6-7 is lower than that in Example 1, and the transmittance of iron oxide in Example 8 is lower than that in Example 4, indicating that the addition of asparagine methyl ester to the scale inhibitor further improves the dispersing performance of the scale inhibitor on iron oxide.

[0082] ④ Scale inhibition performance of silicon and aluminum

[0083] The scale inhibition performance of silicon and aluminum was evaluated using a dynamic scale inhibition test evaluation device operating in full circulation mode. After 30 minutes of operation, when the system's feed water flow rate, permeate flow rate, and concentrate flow rate stabilized, initial data such as flow rate, pressure, conductivity, and ion concentration were recorded. Changes in system flow rate, pressure, and conductivity were recorded every 2 hours. The experiment ended after 48 hours of operation or when the system permeate flow rate reached 0.5 L / h during the experiment. Changes in pH, conductivity, hardness, and alkalinity of the raw water before and after the experiment were measured. The reverse osmosis membrane was removed, drained for 24 hours, weighed, and its mass change was recorded.

[0084] Experimental water: Ca 2+ The concentration was 350 mg / L, Mg 2+ The concentration of the active ingredient was 400 mg / L, the concentration of SiO2 was 30 mg / L, and 10 mg / L of scale inhibitor was added. The experimental temperature was 25℃, with the group without scale inhibitor serving as a blank control group. The pH was adjusted to 7.2, the initial feed water flow rate was 9.5 L / h, and the experimental time was 24 h. The quality changes of the reverse osmosis membrane were recorded. Similarly, a polyaluminum chloride solution (Al) was prepared. 3+ The concentration of the antiscalant was 200 mg / L, the experimental temperature was 30℃, 10 mg / L of antiscalant was added, the experimental time was 24 h, and the quality changes of the reverse osmosis membrane were recorded.

[0085] Table 1. Scale inhibition performance of scale inhibitors on silicon and aluminum.

[0086]

[0087]

[0088] As shown in Table 1, after the experiment, the weight gain of silicate in the reverse osmosis membrane in Examples 1-3 was less than 16g, and the weight gain of aluminum ions in the reverse osmosis membrane was less than 1.9g, which was lower than that of the blank group. This indicates that the scale inhibitor prepared by this invention has excellent silicon and aluminum inhibition properties, preventing silicate and aluminum hydroxide colloids from forming fouling on the reverse osmosis membrane, thereby achieving better scale inhibition performance. In Examples 4-5, the weight gain of silicate in the reverse osmosis membrane was less than 12g, and the weight gain of aluminum ions in the reverse osmosis membrane was less than 1.6g, which was lower than that of Example 1. This indicates that the addition of lignin derivatives obtained by oxidation and pyridinol esterification of lignin to the scale inhibitor improves the surface area of ​​the membrane. The scale inhibitors exhibited improved scale inhibition performance against silicates and aluminum ions. In Examples 6-7, the weight gain of silicates in the reverse osmosis membrane was less than 14g, and the weight gain of aluminum ions in the reverse osmosis membrane was less than 1.7g. In Example 8, the weight gain of silicates in the reverse osmosis membrane was less than 10g, and the weight gain of aluminum ions in the reverse osmosis membrane was less than 1.3g. Among these, the scale inhibition performance of Examples 6-7 against silicates and aluminum ions was better than that of Example 1, and the scale inhibition performance of Example 8 against silicates and aluminum ions was better than that of Example 4. This indicates that the addition of lignin derivatives and asparagine methyl ester to the scale inhibitor further improved the scale inhibition performance against silicates and aluminum ions.

[0089] The conventional operations in the operation steps of this invention are well known to those skilled in the art and will not be described in detail here.

[0090] The embodiments described above provide a detailed explanation of the technical solution of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A scale inhibitor, comprising: Component a, component b; The weight ratio of component a to component b is 2-10:5-20; Component a includes a copolymer of acrylic acid and maleic anhydride; Component b includes organophosphonic acid and copolymers; the organophosphonic acid includes at least one of diethylenetriaminepentamethylenephosphonic acid, aminotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylenephosphonic acid, and 2-hydroxyphosphonoacetic acid; the copolymers include at least one of polyepoxysuccinic acid, ammonium polyacrylate, AA / AMPS binary copolymers, and phospho-based polycarboxylic acid copolymers. Scale inhibitors also include lignin derivatives, which are obtained by oxidation and pyridinol esterification of lignin; The scale inhibitor in Ca 2+ In a solution with a concentration of 2000 mg / L, the calcium tolerance is higher than 820 mg / L; The scale inhibitor also contains 5-10 wt% of component a, asparagine methyl ester.

2. The scale inhibitor as described in claim 1, characterized in that: Component b includes diethylenetriamine pentamethylphosphonic acid and polyepoxysuccinic acid.

3. The scale inhibitor as described in claim 2, characterized in that: In component b, the weight ratio of diethylenetriaminepentamethylphosphonic acid to polyepoxysuccinic acid is 2-7:1-5.

4. The use of the scale inhibitor according to claim 1 in the RO membrane for high-salinity wastewater recovery.

5. The use as described in claim 4, characterized in that: The scale inhibitor is used in high-salt wastewater at a dosage of 30-80 mg / L.

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