Method and production system for extracting humic acid and fulvic acid in drinking water source water

Abstract

The invention discloses a method for extracting humic acid and fulvic acid in drinking water source water and a production system, and belongs to the field of resource recovery and reutilization of natural organic matters in the drinking water source water. The method comprises the following steps: S1, carrying out adsorption treatment on the drinking water source water by using magnetic resin; s2, eluting the magnetic resin through a regenerant to obtain a resin desorption solution; s3, performing electrodialysis on the resin desorption solution to obtain a second-stage desalinated solution; s4, adsorbing, eluting, separating and acidifying the second-stage desalinated liquid through macroporous adsorption resin to obtain humic acid and fulvic acid; wherein in the step S1, the magnetic resin is NDMP-3 resin, and in the step S3, the salt content of the second-stage desalination liquid is 0.49-0.8%. The method is mainly used for extracting humic acid and fulvic acid with high purity and low molecular weight from a drinking water source.

Description

Technical Field

[0001] The invention relates to the technical field of natural organic matter resource recovery and reuse of drinking water source water, and more specifically to a method and a production system for extracting humic acid and fulvic acid from drinking water source water. Background Art

[0002] The use of anion exchange resin adsorption is a deep treatment technology for drinking water, which can be used to effectively remove natural organic matter (NOM) in raw water, and natural organic matter is mainly composed of humus. Due to the advantages of anion exchange technology such as simple operation, adjustable structure, on-site regeneration and no addition of new substances, it has been widely used in the field of deep treatment of drinking water.

[0003] Through the process of adsorption-regeneration of drinking water sand filter water by anion exchange resin, low-concentration humus in drinking water source water can be enriched and concentrated in the resin desorption liquid. Resin desorption liquid is a high-salt and high-organic wastewater containing excessive inorganic salts (mainly NaCl) and high-concentration humus desorbed from the resin. Drinking water source water purification resin desorption liquid contains a high concentration of humus, mainly composed of humic acid (HA) and fulvic acid (FA). Humic acid and fulvic acid extracted from the resin desorption liquid contain high concentrations of oxygen-containing functional groups (carboxyl and phenolic hydroxyl groups), low molecular weight and hydrophilicity, which can stimulate plant growth and metabolism and can be used in industry and agriculture. In addition, humic acid and fulvic acid can be extracted from the desorption liquid of the drinking water purification resin, and it is expected to produce humic acid and fulvic acid standards. At present, the international standards of aquatic humic acid and fulvic acid are mainly purchased from the International Humic Substances Society (IHSS). They are extracted from the Suwannee River through XAD-8 resin and are expensive. At present, there is no method to effectively extract humic acid and fulvic acid from drinking water sources.

[0004] The Chinese patent application document with publication number CN107935238A discloses a process for resource recycling of byproduct humic acid in the process of water purification. The application discloses the process flow: the water to be purified is pumped into the resin adsorption reactor, fully reacted in the reactor, the humic acid in the water is adsorbed by the resin, and the adsorption saturated resin enters the regeneration reactor to realize the desorption and regeneration of the resin. In this process, the humic acid adsorbed on the resin is desorbed by the regeneration agent and becomes a desorption liquid, realizing the enrichment of humic acid; the desorption liquid contains high concentrations of inorganic salts and humic acid, and the regeneration agent and humic acid are separated by an electric drive membrane. The separated humic acid-containing wastewater enters the ultrafiltration membrane, which can realize the further concentration of humic acid. The humic acid in the final concentrated solution can meet the concentration requirements of liquid fertilizers, but the purity is still low. Summary of the invention

[0005] 1. Technical problem to be solved by the invention

[0006] The purpose of the present invention is to overcome the deficiency in the prior art that high-purity low-molecular-weight humic acid and fulvic acid cannot be extracted from drinking water sources, and to provide a method and a production system for extracting humic acid and fulvic acid from drinking water sources.

[0007] 2. Technical solution

[0008] In order to achieve the above object, the technical solution provided by the present invention is:

[0009] A method for extracting humic acid and fulvic acid from drinking water source water of the present invention comprises the following steps:

[0010] S1. Using magnetic resin to adsorb the drinking water source water;

[0011] S2. eluting the magnetic resin by a regeneration agent to obtain a resin desorption liquid;

[0012] S3. Electrodialyzing the resin desorption liquid to obtain a second-stage desalinated liquid;

[0013] S4. The second-stage desalinated liquid is adsorbed by a macroporous adsorption resin, eluted, separated, and acidified to obtain humic acid and fulvic acid;

[0014] Wherein, in step S1, the magnetic resin includes NDMP-3 resin,

[0015] In step S3, the salt content of the second-stage desalinated liquid is 0.49-0.8%.

[0016] Preferably, the salt content of the second-stage desalinated liquid is 0.49-0.5%.

[0017] It should be noted that the method uses an integrated process of magnetic resin adsorption, electromembrane separation, and macroporous adsorption resin adsorption technology to extract humic acid and fulvic acid from drinking water source water, wherein the magnetic resin used for magnetic resin adsorption is NDMP-3 resin, and the humic acid and fulvic acid in the drinking water source water react with the exchangeable Cl on the magnetic resin. - The ion groups undergo ion exchange and are adsorbed onto the magnetic resin. The saturated magnetic resin is desorbed with a regeneration agent to form a resin desorption liquid, which is then separated by an electromembrane to obtain a second-stage desalination liquid with a salt content of 0.49-0.8%. The concentrations of humic acid and fulvic acid in the second-stage desalination liquid are relatively high. The humic acid and fulvic acid in the second-stage desalination liquid are purified by macroporous adsorption resin adsorption technology to obtain humic acid and fulvic acid with high purity and low molecular weight.

[0018] It should also be noted that the content, molecular weight, and hydrophilicity of humic acid and fulvic acid contained in different sample matrices (such as soil, peat, lignite, water samples, etc.) are all different, and have great differences, which also leads to great differences in the extraction methods. However, the applicant has found through a large number of studies and experiments that the method can be used to extract humic acid and fulvic acid from drinking water sources, and the extracted humic acid and fulvic acid are consistent with the standard products of the International Humic Substances Society (IHSS) in terms of fluorescence characteristics, ultraviolet absorption characteristics, functional groups and structures, but their molecular weights are lower than the molecular weight of the standard products of the International Humic Substances Society (IHSS), and their hydrophilicity is stronger.

[0019] Preferably, when the salt content is between 0.49% and 0.5%, the salt content in the second-stage desalinated liquid is lower, which is more conducive to improving the purity of the extracted humic acid and fulvic acid;

[0020] When the salt content of the second-stage desalinated liquid is less than 0.49%, the energy consumption of the electrodialysis treatment will increase; when the salt content of the second-stage desalinated liquid is greater than 0.8%, the amount of water used for washing in subsequent steps and the purity of the extracted humic acid and fulvic acid will increase.

[0021] Furthermore, the NDMP-3 resin was purchased from Jiangsu Guoxin Innovation Materials Research Center Co., Ltd.

[0022] Furthermore, the macroporous adsorption resin includes NDA-8 resin.

[0023] The NDA-8 resin has a lower specific surface area (116 m 2 / g) and pore volume (0.32cm 3 / g), with a relatively large average pore size (10.98nm), and a better adsorption effect on humic acid and fulvic acid.

[0024] Preferably, the macroporous adsorption resin is NDA-8, purchased from Jiangsu National Innovation Materials Research Center Co., Ltd.

[0025] Furthermore, in step S1, the temperature of the adsorption treatment is 0 to 35°C, and the adsorption residence time is 10 to 30 minutes.

[0026] Furthermore, the drinking water source water is drinking water source water that complies with the drinking water source water quality standard CJ 3020-1993.

[0027] Furthermore, before step S1, the drinking water source water is filtered to remove particulate matter, suspended matter, etc. in the drinking water source water.

[0028] For example, the filtration may be sand filtration.

[0029] Furthermore, in step S2, the regeneration agent is one or both of sodium chloride solution and hydrochloric acid solution.

[0030] Preferably, the regeneration agent is a sodium chloride solution, and the mass concentration of the sodium chloride solution is 15% to 20%.

[0031] Furthermore, in step S2, the elution temperature is 0 to 35°C, and the residence time is 10 to 30 minutes.

[0032] Further, in step S3, the electrodialysis includes a first-stage electrodialysis and a second-stage electrodialysis,

[0033] Performing first-stage electrodialysis on the resin desorption liquid to obtain first-stage concentrated liquid and first-stage desalinated liquid;

[0034] The first-stage desalinated liquid is subjected to second-stage electrodialysis to obtain second-stage desalinated liquid.

[0035] Further, the first stage electrodialysis ends when the salt content of the first stage concentrated solution is 14% to 16%;

[0036] The second stage electrodialysis ends when the salt content of the second stage desalinated liquid is 0.49-0.8%.

[0037] Further, the conditions of the first stage electrodialysis are: using 10 pairs of ion exchange membrane pairs, the volume ratio of the initial concentrate to the resin desorption liquid is 1:2 to 1:4, and the flow ratio of the resin desorption liquid in the desalination chamber to the concentrate in the concentration chamber is 2:1 to 1:2;

[0038] The conditions of the second-stage electrodialysis are: using 10 pairs of ion exchange membranes, the volume ratio of the initial concentrated liquid to the first-stage desalinated liquid is 1:2 to 1:4, and the flow ratio of the first-stage desalinated liquid in the desalination chamber to the concentrated liquid in the concentration chamber is 2:1 to 1:2;

[0039] In the first-stage electrodialysis and the second-stage electrodialysis, the initial concentrated solution is one or both of distilled water and tap water.

[0040] Furthermore, the first-stage electrodialysis and the second-stage electrodialysis are both performed in a direct current constant voltage manner.

[0041] Furthermore, the voltage is 12-16V.

[0042] It should be noted that by using an electrodialyzer to perform electrodialysis to separate humus from the regeneration agent sodium chloride solution, the simultaneous recovery and utilization of inorganic salts, fulvic acid and humic acid can be achieved; inorganic ions (inorganic salts) pass through one side of the ion exchange membrane under the driving action of direct current, while humus is retained by the ion exchange membrane on the other side, thereby achieving the recovery and utilization of sodium chloride.

[0043] Furthermore, the method further comprises S5. using the first concentrated liquid as a regeneration agent for elution in step S2.

[0044] It should be noted that the first concentrated liquid can be circulated and used as a regeneration agent for regenerating saturated magnetic resin, and the regeneration efficiency is equivalent to that of an unused regeneration agent.

[0045] Furthermore, the step S4 specifically includes the following steps:

[0046] S41. Using an acidic solution to adjust the pH value of the second-stage desalinated liquid to 2 to 3;

[0047] The macroporous adsorption resin is used to adsorb the humic acid and fulvic acid in the second-stage desalination liquid.

[0048] The flow rate of the second-stage desalinated liquid is 10-12 BV / h;

[0049] S42. Eluting with a macroporous adsorption resin using an alkaline solution to obtain a mixed solution containing humic acid and fulvic acid, and acidifying the mixed solution with an acidic solution to a pH value of 1 to 2;

[0050] The flow rate of the alkaline solution is 1 to 2 BV / h;

[0051] S43. The mixed solution is subjected to solid-liquid separation to obtain a humic acid solid and a supernatant containing fulvic acid;

[0052] S44. Wash the humic acid solids with water until there is no Cl in the effluent - , using an alkaline solution to dissolve the humic acid solid to obtain a humate solution;

[0053] Acidifying the humate solution with 732 type strong acid resin to obtain a humic acid solution;

[0054] The flow rate of the humate solution is 10-12 BV / h;

[0055] S45. adjusting the pH value of the supernatant to 2 to 3 with an alkaline solution, re-adsorbing the fulvic acid in the supernatant with a macroporous adsorption resin, and eluting the macroporous adsorption resin with an alkaline solution to obtain an eluate containing fulvic acid salt;

[0056] Acidifying the eluent containing fulvic acid salt by using 732 type strong acid resin to obtain a fulvic acid solution;

[0057] The flow rate of the supernatant is 10-12 BV / h;

[0058] The flow rate of the eluent containing fulvic acid salt is 10-12 BV / h.

[0059] Preferably, in step S45, after obtaining the eluent containing fulvic acid salt, it is immediately acidified by 732 type strong acid resin to reach hydrogen saturation, and the obtained fulvic acid solution substantially does not contain fulvic acid salt.

[0060] Furthermore, the step 4 also includes S46. freeze-drying the humic acid solution obtained in step S44 and the fulvic acid solution obtained in step S45 to obtain humic acid solid and fulvic acid solid.

[0061] Further, the alkaline solution includes NaOH solution;

[0062] The acidic solution includes a hydrochloric acid solution.

[0063] For example, the alkaline solution may be a NaOH solution with a concentration of 0.1 to 0.2 mol / L.

[0064] Furthermore, the 732 type strong acid resin includes 732 type strong acid styrene cation exchange resin.

[0065] Furthermore, the 732 type strong acid resin is filled in the resin column.

[0066] Furthermore, in step S41, water washing is further performed after adsorption by the macroporous adsorption resin to elute humic acid and fulvic acid that are not adsorbed by the macroporous adsorption resin.

[0067] Furthermore, in step S42, the saturated macroporous adsorption resin is eluted with an alkaline solution.

[0068] Furthermore, in step S43, the solid-liquid separation may be carried out by a combination of one or more of centrifugation, filtration and suction filtration.

[0069] Preferably, the solid-liquid separation is carried out by combining centrifugation and suction filtration.

[0070] Furthermore, in step S45, the macroporous adsorption resin is washed with water after re-adsorption to remove salts such as NaCl.

[0071] Furthermore, after the acidification of the 732 type strong acid resin, water washing is also included to fully desorb the humic acid and fulvic acid.

[0072] Furthermore, ultrapure water may be used in the water washing.

[0073] The present invention also provides a production system using the above method for extracting humic acid and fulvic acid from drinking water source water, characterized in that:

[0074] The production system comprises a resin adsorption reactor, a regeneration reactor, an electrodialyzer, a first macroporous adsorption resin reactor and a purification unit connected in sequence;

[0075] The purification unit includes a humic acid purification component and a fulvic acid purification component respectively connected to the first macroporous adsorption resin reactor;

[0076] The humic acid purification assembly includes a first 732 type strong acid resin column,

[0077] The fulvic acid purification component comprises a second macroporous adsorption resin reactor and a second 732 type strong acid resin column which are connected in sequence.

[0078] Furthermore, the electrodialyzer may refer to the electrodialysis device in Example 1 disclosed in Chinese Patent Publication No. CN107224999A.

[0079] Furthermore, the electrodialyzer includes a membrane stack, an electrode chamber, a desalination chamber, and a concentration chamber.

[0080] The membrane stack includes 10 pairs of anion and cation exchange membranes.

[0081] The cation exchange membrane in the anion and cation exchange membrane pair may be a TWEDC1 homogeneous cation membrane;

[0082] The anion exchange membrane may be a TWEDA1 homogeneous anion exchange membrane.

[0083] Furthermore, the resin adsorption reactor is filled with the magnetic resin;

[0084] The magnetic resin includes NDMP-3 resin.

[0085] Furthermore, the first macroporous adsorption resin reactor and the second macroporous adsorption resin reactor are both filled with macroporous adsorption resin;

[0086] The macroporous adsorption resin includes NDA-8 resin.

[0087] Further, the first 732-type strong acid resin column and the second 732-type strong acid resin column are both filled with 732-type strong acid resin;

[0088] The 732 type strong acid resin includes 732 type strong acid styrene cation exchange resin.

[0089] Furthermore, the system comprises a filtering device for sand filtering the drinking water source water.

[0090] 3. Beneficial effects

[0091] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0092] (1) The present invention provides a method for extracting humic acid and fulvic acid from drinking water source water, wherein the method uses an integrated process of magnetic resin adsorption, electromembrane separation (electrodialysis), and macroporous adsorption resin adsorption technology to extract humic acid and fulvic acid from drinking water source water, wherein the magnetic resin used for magnetic resin adsorption is NDMP-3 resin, and the humic acid and fulvic acid in the drinking water source water react with the exchangeable Cl on the magnetic resin. - The ion groups undergo ion exchange and are adsorbed and enriched on the magnetic resin. The saturated magnetic resin is desorbed by a regeneration agent, and then a resin desorption liquid is formed. Then, a second-stage desalination liquid with a salt content of 0.49-0.8% is obtained by electro-membrane separation. Moreover, the concentration of humic acid and fulvic acid in the second-stage desalination liquid is relatively high. Then, the humic acid and fulvic acid in the second-stage desalination liquid are purified by macroporous adsorption resin adsorption technology to obtain humic acid and fulvic acid with high purity and low molecular weight.

[0093] Moreover, the extracted humic acid and fulvic acid are consistent with the standards of the International Humic Substances Society (IHSS) in terms of fluorescence characteristics, ultraviolet absorption characteristics, functional groups and structures, but their molecular weights are lower than that of the standards of the International Humic Substances Society (IHSS) and are more hydrophilic.

[0094] (2) The method for extracting humic acid and fulvic acid from drinking water source water provided by the present invention realizes resource recovery of the pollutants humic acid and fulvic acid through a separation method, and the intermediate regeneration agent, magnetic resin, etc. can be recycled, which has good environmental benefits, economic benefits, and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Figure 1 This is a schematic flow chart of a method for extracting humic acid and fulvic acid from drinking water source water in Example 1 of the present invention;

[0096] Figure 2This is a schematic diagram of the process of extracting humic acid and fulvic acid from the resin desorption liquid of drinking water source water in Example 1 of the present invention;

[0097] Figure 3 The three-dimensional fluorescence excitation emission matrix (EEM) spectra of HA (a) and FA (c) of the International Humic Substances Society (IHSS) and HA (b) and FA (d) extracted in Example 1;

[0098] Figure 4 SEC-DAD-FLD-OCD-OND analysis of HA (a) from the International Humic Substances Society (IHSS) and HA (b) extracted in Example 1;

[0099] Figure 5 SEC-DAD-FLD-OCD-OND analysis of FA (a) from the International Humic Substances Society (IHSS) and FA (b) extracted in Example 1;

[0100] Figure 6 The infrared spectra of HA of the International Humic Substances Society (IHSS) and the HA extracted in Example 1 (a) and the infrared spectra of FA of the International Humic Substances Society (IHSS) and the FA extracted in Example 1 (b);

[0101] Figure 7 The contact angles of HA (a) and FA (b) of the International Humic Substances Society (IHSS) and HA (c) and FA (d) extracted in Example 1. DETAILED DESCRIPTION

[0102] The present disclosure may be more easily understood by reference to the following description in conjunction with examples, all of which constitute a part of the present disclosure. It should be understood that the present disclosure is not limited to the specific products, methods, conditions or parameters described and / or illustrated herein. Further, the terms used herein are only used for the purpose of describing specific embodiments by way of example and are not intended to be limiting unless otherwise indicated.

[0103] It should also be understood that, for the sake of clarity, certain features of the present disclosure may be described herein in the context of separate embodiments, but may also be provided in combination with each other in a single embodiment. That is, unless clearly incompatible or specifically not included, each separate embodiment is considered to be combinable with any other embodiment, and the combination is considered to represent another different embodiment. Conversely, for the sake of simplicity, the various features of the present disclosure described in the context of a single embodiment may also be provided individually or in any sub-combination. Finally, although a particular embodiment may be described as part of a series of steps or part of a more general structure, each step or substructure itself may also be considered to be an independent embodiment.

[0104] Unless otherwise indicated, it should be understood that each individual element in a list and each combination of individual elements in the list will be interpreted as a different embodiment. For example, a list of embodiments represented as "A, B, or C" should be interpreted to include embodiments "A", "B", "C", "A or B", "A or C", "B or C", or "A, B, or C".

[0105] When items are described by using the conjunction terms "... and / or...," etc., the description should be understood to include any one of the associated listed items and all combinations of one or more thereof.

[0106] In general, the use of the term "about" indicates an approximate value that can vary depending on the desired properties obtained by the disclosed subject matter, and will be interpreted in a context-dependent manner based on function. Therefore, one of ordinary skill in the art will be able to interpret a certain degree of difference on a case-by-case basis. In some cases, the number of significant figures used when expressing a particular value can be a representative technique for determining the difference allowed by the term "about". In other cases, a gradient in a range of values ​​can be used to determine the range of differences allowed by the term "about". Further, all ranges in this disclosure are inclusive and combinable, and reference to a value in a range includes each value within that range.

[0107] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs; the terms used herein and / or include any and all combinations of one or more of the associated listed items.

[0108] In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are all conventional products that can be purchased commercially.

[0109] NDA-8 resin, 732 strong acid styrene cation exchange resin, and NDMP-3 resin were all purchased from Jiangsu Guoxin Innovation Materials Research Center Co., Ltd.; ion exchange membrane TWEDC1 and ion exchange membrane TWEDA1 were both purchased from Shandong Tianwei Membrane Technology Co., Ltd.

[0110] The present invention is further described below in conjunction with specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art. The essential characteristics and remarkable effects of the present invention can be reflected from the following examples, and the described embodiments are part of the embodiments of the present invention, rather than all the embodiments, and therefore, they do not limit the present invention in any way, and those skilled in the art make some non-essential improvements and adjustments based on the content of the present invention, which all belong to the protection scope of the present invention.

[0111] Example 1

[0112] A water company in Yancheng City has established a 25,000 ton / day drinking water deep treatment demonstration project. The deep drinking water treatment process based on magnetic resin adsorption is adopted, and the supporting resource recovery devices are: the production system includes a resin adsorption reactor, a regeneration reactor, an electrodialyzer, a first macroporous adsorption resin reactor and a purification unit connected in sequence; the purification unit includes a humic acid purification component and a fulvic acid purification component connected to the first macroporous adsorption resin reactor respectively; the humic acid purification component includes a first 732 type strong acid resin column, and the fulvic acid purification component includes a second macroporous adsorption resin reactor and a second 732 type strong acid resin column connected in sequence. Among them, the resin adsorption reactor is filled with NDMP-3 resin; the electrodialysis device in Example 1 of the Chinese patent disclosure with the electrodialyzer publication number CN107224999A; the first 732 type strong acid resin column and the second 732 type strong acid resin column are both filled with 732 type strong acid styrene cation exchange resin; the first macroporous adsorption resin reactor and the second macroporous adsorption resin reactor are both filled with NDA-8 resin, also respectively referred to as the first NDA-8 resin reactor and the second NDA-8 resin reactor.

[0113] Combination Figure 1 and Figure 2 In this embodiment, a method for extracting humic acid and fulvic acid from drinking water source water by resin method is provided, and the specific steps are as follows:

[0114] (1) The drinking water filtered out by sand is pumped into a resin adsorption reactor, in which the magnetic resin NDMP-3 resin is loaded. The magnetic resin adsorbs humus in the water filtered out by sand, thereby achieving the purpose of removing humus in the water body; the adsorption temperature of the resin adsorption reactor is 25°C, and the adsorption residence time is 30 minutes.

[0115] Resin adsorption reactor influent COD Mn About 3.8mg / L, effluent COD Mn It is about 2.3mg / L. After passing through the resin adsorption reactor, COD Mn The removal efficiency is 39%;

[0116] (2) The saturated magnetic resin is transported to the regeneration reactor, and sodium chloride solution is added to elute the saturated resin. The humus adsorbed on the resin is desorbed and concentrated to become a drinking water source water purification resin desorption liquid; the regeneration reaction temperature of the regeneration reactor is 25°C, and the residence time is 30 minutes; the resin desorption liquid COD Mn The concentration is about 2960mg / L and the salt content is about 9.5%;

[0117] (3) In this embodiment, two-stage electrodialysis is used to desalinate 4 L of the resin desorption liquid taken from step (2), and the above resin desorption liquid is pumped into the electrodialyzer to separate the humus and inorganic salts in the desorption liquid; wherein the two-stage electrodialysis includes a first-stage electrodialysis and a second-stage electrodialysis, and the conditions of the first-stage electrodialysis are: using 10 pairs of TWEDC1 / TWEDA1 ion exchange membrane pairs, the volume ratio of distilled water to resin desorption liquid is 1:3, and the flow ratio of resin desorption liquid to distilled water is 1: :1, adopting DC constant voltage operation mode, wherein the resin desorption liquid is added to the desalination chamber, distilled water is added to the concentration chamber, and the voltage is 14V; the conditions for the second stage electrodialysis are: using 10 pairs of TWEDC1 / TWEDA1 ion exchange membrane pairs, the volume ratio of distilled water to the first stage desalination liquid is 1:3, the flow ratio of the first stage desalination liquid to distilled water is 1:1, and adopting DC constant voltage operation mode, wherein the first stage desalination liquid is added to the desalination chamber, distilled water is added to the concentration chamber, and the voltage is 14V.

[0118] After the resin desorption liquid is treated by the first stage electrodialysis, the COD in the first stage electrodialysis concentrate (concentrated high inorganic salt solution) Mn The concentration is about 240.2mg / L, the salinity is about 14.9%, and it can be reused for saturated magnetic resin regeneration; the first-stage desalination liquid of electrodialysis (concentrated high-concentration humus solution) COD Mn The concentration is 4930 mg / L and the salinity is about 0.67%. The first-stage concentrated solution (concentrated high inorganic salt solution) is added to step (2) and is continuously circulated as a regeneration agent. The first-stage concentrated solution can be directly used as a resin regeneration agent for regeneration of saturated magnetic resin, and the regeneration efficiency is equivalent to that of an unused regeneration agent.

[0119] After the first-stage electrodialysis desalination liquid is subjected to the second-stage electrodialysis treatment, 2660 mL of the second-stage desalination liquid (the low-salt and high-concentration humus solution, i.e., the recovered humus solution) is obtained. The COD Mn The concentration is 5151 mg / L, the total organic carbon is 6855 mg / L, and the salinity is about 0.49%.

[0120] (4) The second-stage desalinated liquid (low-salt, high-concentration humus solution) separated in step (3) was adjusted to pH 2.0 with concentrated hydrochloric acid, and the HA and FA therein were retained in a 75 mL first NDA-8 resin reactor at a flow rate of 12 BV / h. After the loading was completed, 300 mL of ultrapure water was used to rinse the resin reactor until the liquid in the resin reactor was drained. HA and FA in the resin reactor were eluted with 270 mL of 0.1 mol / L NaOH at a flow rate of 2 BV / h, and immediately acidified to pH 1 with HCl to prevent oxidation of humus. HA solid and FA supernatant were separated by centrifugation and filtration, and the HA solid was repeatedly washed with ultrapure water until there was no Cl in the effluent. - , add enough 0.1mol / L NaOH to dissolve the HA solid, then pass through 160mL of the first 732-type strong acid resin column for acidification, flow rate 12BV / h, and rinse with 200mL of ultrapure water, and collect in the HA solution. Adjust the pH of the FA supernatant to 2.0 with NaOH solution, re-adsorb FA on the 75mL second NDA-8 resin reactor, flow rate 12BV / h, and wash with 400mL of ultrapure water to remove salts. Elute the FA in the resin reactor with 270mL of 0.1mol / L NaOH. Immediately pass the FA eluate through a 160mL second 732-type strong acid resin column to achieve hydrogen saturation, flow rate 12BV / h, and rinse with 200mL of ultrapure water, and collect in the FA solution.

[0121] Finally, the HA and FA solutions were freeze-dried into solid powders to obtain extracted powdered humic acid and fulvic acid, and 285 mg C HA (561.6 mg HA) and 1.19 g C FA (2.3 g FA) were obtained.

[0122] After the inorganic salts in the extracted humic acid and fulvic acid solutions were determined by ion chromatography, it was found that Cl - Concentration less than 10mg / L, NO3 - Concentration less than 3mg / L, SO4 2- Less than 1mg / L, NH4 + The concentration was less than 5 mg / L, indicating that the concentration of inorganic salts in the extracted HA and FA solutions was low.

[0123] Fluorescence characteristics of humic acid and fulvic acid extracted ( Figure 3 )、UV absorption characteristics( Figure 4 , Figure 5 ), functional groups and structures ( Figure 6 ) are basically the same as HA and FA of IHSS, but their molecular weights are lower than those of HA and FA of IHSS. Figure 5 It can be seen that the apparent molecular weight range of FA of IHSS is 2.3×10 4Da to 500 Da, with a weight-average molecular weight of 5303 Da, while the apparent molecular weight range of the extracted FA is 1.5×10 4 Da to 500 Da, with a weight-average molecular weight of 3835 Da; from Figure 4 it can be seen that the apparent molecular weight range of the HA of IHSS is 3.8×10 4 Da to 500 Da, with a weight-average molecular weight of 7040 Da, while the apparent molecular weight range of the extracted HA is 3.7×10 4 Da to 500 Da, with a weight-average molecular weight of 5418 Da, and the molecular weight of the extracted HA is smaller. In addition, combined with Figure 7 , the extracted HA and FA are more hydrophilic.

[0124] Specifically, combined with Figure 4 , a SEC-DAD-FLD-OCD-OND system was used to analyze the composition and properties of the HA of IHSS and the extracted HA. In the DAD detector, the ultraviolet absorbance at >240 nm is usually used to analyze and characterize the aromatic components in dissolved organic matter (DOM); the fluorescence detector responds to protein-like fluorescence (Em < 380 nm) and humic-like fluorescence (Em > 380 nm) of DOM; the organic carbon detector responds to organic carbon, while the organic nitrogen detector responds to organic nitrogen and nitrite nitrogen, nitrate nitrogen and ammonia nitrogen. The apparent molecular weight range of the HA of IHSS is 3.8×10 4 Da to 500 Da, with a weight-average molecular weight of 7040 Da, while the apparent molecular weight range of the extracted HA is 3.7×10 4 Da to 500 Da, with a weight-average molecular weight of 5418 Da, and the molecular weight of the extracted HA is smaller. They both have strong ultraviolet (UV > 240 nm) absorption, indicating that they both have relatively strong aromaticity and contain conjugated aromatic hydrocarbons or conjugated systems such as double bonds, carbonyl groups, and carboxyl groups. Humic-like fluorescence with Em > 380 nm can be observed in their FLD spectra, including humic-like fluorescence generated by humic substances and building-block humic-like substances (apparent molecular weight AMW is located in the range of 1.3 kDa to 500 Da). However, two sub-components HA-1 (1 kDa < MW < 3.8 kDa) and HA-2 (3.8 kDa < MW < 20 kDa) appeared in the extracted HA. In the OND spectrum, they both have peaks of organic nitrogen, but the HA of IHSS has more inorganic nitrogen (nitrite nitrogen, nitrate nitrogen and ammonia nitrogen) at the position of apparent molecular weight < 500 Da than the extracted HA, indicating that the extracted HA contains less nitrogen-containing inorganic impurities.

[0125] Combined with Figure 5 , the apparent molecular weight range of the FA of IHSS is 2.3×10 4Da to 500 Da, the weight-average molecular weight is 5303 Da, while the apparent molecular weight range of the extracted FA is 1.5×10 4 Da to 500 Da, the weight-average molecular weight is 3835 Da, and the molecular weight of the extracted FA is smaller. They both have strong ultraviolet (UV>240 nm) absorption, indicating strong aromaticity. Humic-like fluorescence with Em>380 nm can be observed in their FLD spectra, including humic-like fluorescence produced by humic substances and building-block humic-like substances (apparent molecular weight AMW is in the range of ~1.3 kDa to 500 Da). Two sub-components, FA-1 (1 kDa < MW < 2.5 kDa) and FA-2 (2.5 kDa < MW < 20 kDa), appeared in the FA of IHSS, while two sub-components, FA-1 (950 Da < MW < 4 kDa) and FA-2 (4 kDa < MW < 15 kDa), also appeared in the extracted FA. In the OND spectra, they both have peaks of organic nitrogen, but the FA of IHSS has more inorganic nitrogen (nitrite nitrogen, nitrate nitrogen, and ammonia nitrogen) at the position of apparent molecular weight <500 Da than the extracted FA, indicating that the extracted FA contains fewer nitrogen-containing inorganic impurities.

[0126] Among them, the determination conditions for ion chromatography are as follows: Ion chromatograph (ICS5000+ ThermoFisher, USA), using IonPac AS11-HC chromatographic column, 20 mmol / L potassium hydroxide solution as the eluent, and adopting isocratic elution mode.

[0127] The test conditions for SEC-DAD-FLD-OCD-OND analysis are as follows: adopting a size-exclusion chromatography (SEC)-diode array detector (DAD)-fluorescence detector (FLD)-organic carbon detector (OCD)-organic nitrogen (OND) detector system, equipped with a diode array detector (DAD, Agilent 1290), a fluorescence detector (FLD, Agilent 1260 Infinity IIG1721B), an on-line organic carbon detector (Turbo Sievers@M9SEC TOC Analyzer, Suez) and installed with a TSKHW-50S size-exclusion column (20 mm×250 mm, DOC-Labor, Karlsruhe, Germany). The organic nitrogen detector includes an ultraviolet oxidation module and an ultraviolet detection module.

[0128] The test conditions of the SEC-DAD-FLD-OCD-OND instrument set are as follows: the chromatographic column is a column filled with TSK HW 50s filler, 250mm×20mm; the mobile phase is a phosphate buffer solution with pH=6.85 (2.5g KH2PO4 and 1.5g Na2HPO4 dissolved in 1L ultrapure water), and an isocratic elution program is used; the flow rate is 1.0mL / min; the column temperature is room temperature; the injection volume is 500μL; the ultraviolet detection wavelength of the DAD detector is from 200nm to 400nm, and the FLD detection wavelength is excitation (E x ) / Emit(E m )=230 / 300~500nm, the ultraviolet wavelength of the organic nitrogen detector is 220nm, and the organic carbon detector is mainly used to test the content of dissolved organic carbon in water samples.

[0129] The weight average molecular weight M of HA and FA w The calculation formula is:

[0130]

[0131] Where M i is the molecular mass value corresponding to the i-th fraction, h i is the peak height of the detector at time i, i.e. the response value, in mV; n represents the total number of fractions.

Claims

1. A method for extracting humic acid and fulvic acid from drinking water source water, characterized in that: The following steps are involved: S1. Using magnetic resin to adsorb the drinking water source water; S2. eluting the magnetic resin by a regeneration agent to obtain a resin desorption liquid; S3. Electrodialyzing the resin desorption liquid to obtain a second-stage desalinated liquid; S4. The second-stage desalinated liquid is adsorbed by a macroporous adsorption resin, eluted, separated, and acidified to obtain humic acid and fulvic acid; Wherein, in step S1, the magnetic resin includes NDMP-3 resin, In step S3, the salt content of the second-stage desalinated liquid is 0.49-0.8%.

2. The method for extracting humic acid and fulvic acid from drinking water source water according to claim 1, characterized in that: In step S3, the electrodialysis includes a first-stage electrodialysis and a second-stage electrodialysis, Performing first-stage electrodialysis on the resin desorption liquid to obtain first-stage concentrated liquid and first-stage desalinated liquid; The first-stage desalinated liquid is subjected to second-stage electrodialysis to obtain second-stage desalinated liquid.

3. The method for extracting humic acid and fulvic acid from drinking water source water according to claim 2, characterized in that: The first stage electrodialysis ends when the salt content of the first stage concentrated solution is 14% to 16%; The second stage electrodialysis ends when the salt content of the second stage desalinated liquid is 0.49-0.8%.

4. The method for extracting humic acid and fulvic acid from drinking water source water according to claim 3, characterized in that: The step S4 specifically comprises the following steps: S41. Using an acidic solution to adjust the pH value of the second-stage desalinated liquid to 2 to 3; The macroporous adsorption resin is used to adsorb the humic acid and fulvic acid in the second-stage desalination liquid. The flow rate of the second-stage desalinated liquid is 10-12 BV / h; S42. Eluting with a macroporous adsorption resin using an alkaline solution to obtain a mixed solution containing humic acid and fulvic acid, and acidifying the mixed solution with an acidic solution to a pH value of 1 to 2; The flow rate of the alkaline solution is 1 to 2 BV / h; S43. The mixed solution is subjected to solid-liquid separation to obtain a humic acid solid and a supernatant containing fulvic acid; S44. Wash the humic acid solids with water until there is no Cl in the effluent - , using an alkaline solution to dissolve the humic acid solid to obtain a humate solution; Acidifying the humate solution with 732 type strong acid resin to obtain a humic acid solution; The flow rate of the humate solution is 10-12 BV / h; S45. adjusting the pH value of the supernatant to 2 to 3 with an alkaline solution, re-adsorbing the fulvic acid in the supernatant with a macroporous adsorption resin, and eluting the macroporous adsorption resin with an alkaline solution to obtain an eluate containing fulvic acid salt; Acidifying the eluent containing fulvic acid salt by using 732 type strong acid resin to obtain a fulvic acid solution; The flow rate of the supernatant is 10-12 BV / h; The flow rate of the eluent containing fulvic acid salt is 10-12 BV / h.

5. The method for extracting humic acid and fulvic acid from drinking water source water according to claim 4, characterized in that: The step 4 also includes S46. freeze-drying the humic acid solution and the fulvic acid solution to obtain humic acid and fulvic acid.

6. The method for extracting humic acid and fulvic acid from drinking water source water according to claim 4, characterized in that: The macroporous adsorption resin includes NDA-8 resin; The 732 type strong acid resin includes 732 type strong acid styrene cation exchange resin.

7. The method for extracting humic acid and fulvic acid from drinking water source water according to claim 6, characterized in that: In step S2, the regeneration agent is one or both of sodium chloride solution and hydrochloric acid solution.

8. The method for extracting humic acid and fulvic acid from drinking water source water according to claim 7, characterized in that: In step S2, the elution temperature is 0 to 35°C, and the residence time is 10 to 30 minutes.

9. The method for extracting humic acid and fulvic acid from drinking water source water according to claim 8, characterized in that: In step S1, the temperature of the adsorption treatment is 0 to 35°C, and the adsorption residence time is 10 to 30 minutes.

10. A production system using the method for extracting humic acid and fulvic acid from drinking water source water according to any one of claims 1 to 9, characterized in that: The production system comprises a resin adsorption reactor, a regeneration reactor, an electrodialyzer, a first macroporous adsorption resin reactor and a purification unit connected in sequence; The purification unit includes a humic acid purification component and a fulvic acid purification component respectively connected to the first macroporous adsorption resin reactor; The humic acid purification assembly includes a first 732 type strong acid resin column, The fulvic acid purification component comprises a second macroporous adsorption resin reactor and a second 732 type strong acid resin column which are connected in sequence.

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