Ion exchange unit, module and device

Abstract

The invention relates to the technical field of ion exchange, in particular to an ion exchange unit, module and device. The ion exchange unit comprises high-selectivity alkali metal ion exchange resin and low-selectivity alkali metal ion exchange resin; impurity ions are allowed to sequentially pass through high-selectivity alkali metal ion exchange resin and low-selectivity alkali metal ion exchange resin in the flowing direction of a water path. The high-selectivity alkali metal ions and the low-selectivity alkali metal ions are capable of exchanging ions with the impurities, and part of the high-selectivity alkali metal ions are replaced and intercepted when entering the low-selectivity alkali metal ion exchange resin. According to the ion exchange unit provided by the invention, the release of high-selectivity alkali metal ions is effectively controlled through the high-selectivity alkali metal ion exchange resin and the low-selectivity alkali metal ion exchange resin which are arranged in a layered manner, so that the service life is remarkably prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of ion exchange, and particularly to an ion exchange unit, module and device. Background Art

[0002] In the field of water treatment, ion exchange technology, as an efficient water purification method, is widely used to remove hardness ions (such as calcium and magnesium ions), heavy metal ions and some anions in water. At the same time, beneficial ions, such as potassium ions, can also be released through specific ion exchange resins to improve water quality or meet specific application requirements. Sodium ion exchange resin and potassium ion exchange resin are two common types among them, and they play a crucial role in the water treatment process.

[0003] Sodium ion exchange resin is mainly used for softening water quality. By exchanging calcium and magnesium ions in water, it can reduce the formation of water scale and improve the water use efficiency, and is widely used in fields such as households, industries and agricultural irrigation. In addition, with the enhancement of environmental awareness, people have begun to explore more environmentally friendly and healthy alternative solutions, and potassium ion exchange resin has thus gradually come into people's view.

[0004] Potassium ion exchange resin, as a new resin material that can release potassium ions and simultaneously adsorb other cations, has a widely promising application prospect in water treatment. Potassium is one of the essential trace elements for the human body, participating in various physiological processes. Appropriate supplementation of potassium helps to maintain heart function, regulate blood pressure, promote muscle contraction, etc. Therefore, using potassium ion exchange resin to treat drinking water or irrigation water can not only effectively remove adverse ions in water, but also increase the potassium content in water, which has positive significance for improving water quality, promoting crop growth and human health.

[0005] However, the problem that the service life of potassium ion exchange resin is severely limited in the actual application process has become a major bottleneck restricting its wide promotion. Specifically, potassium ion exchange resin can release a relatively high concentration of potassium ions in the initial use stage, usually reaching about 100 ppm, which is very beneficial for improving water quality and meeting specific requirements. However, as the amount of treated water increases, the potassium ion release ability of the resin rapidly decreases. Research shows that after treating only 120 liters of water, the release rate of potassium ion exchange resin almost drops to zero, which means that the exchange capacity of the resin is close to saturation and it can no longer effectively release potassium ions.

[0006] The root cause of this phenomenon lies in the exchange sites and structural characteristics of potassium ion exchange resin. During the exchange process, the active groups on the resin will undergo a displacement reaction with the ions in water. As the reaction progresses, the exchangeable potassium ions are gradually replaced by other cations in water (such as calcium, magnesium, sodium, etc.), resulting in a rapid decline in the potassium ion release capacity of the resin. In addition, the physical structure, chemical stability, and regeneration ability of the resin are also important factors affecting its service life. Once the resin reaches a saturated state, if it cannot be regenerated by effective means, only a new resin can be replaced, which undoubtedly increases the water treatment cost and limits the wide application of potassium ion exchange resin.

[0007] Therefore, how to improve the potassium ion release life of potassium ion exchange resin has become an urgent technical problem to be solved in the current water treatment field. Summary of the Invention

[0008] To solve the deficiencies in the above-mentioned prior art, the present invention provides an ion exchange unit, module, and device.

[0009] To solve the above technical problems, one of the technical solutions provided by the present invention is as follows:

[0010] An ion exchange unit, the ion exchange unit includes:

[0011] A highly selective alkali metal ion exchange resin and a low-selectivity alkali metal ion exchange resin;

[0012] It allows impurity ions to sequentially pass through the highly selective alkali metal ion exchange resin and the low-selectivity alkali metal ion exchange resin along the water flow direction, so that the effluent contains highly selective alkali metal ions and low-selectivity alkali metal ions that can exchange with the impurity ions, and part of the highly selective alkali metal ions are displaced and intercepted when entering the low-selectivity alkali metal ion exchange resin.

[0013] In one embodiment, the release amount of highly selective alkali metal ions in the highly selective alkali metal ion exchange resin is greater than the release amount of low-selectivity alkali metal ions in the low-selectivity alkali metal ion exchange resin.

[0014] In one embodiment, the thickness of the highly selective alkali metal ion exchange resin is greater than that of the low-selectivity alkali metal ion exchange resin; and / or

[0015] The highly selective alkali metal ion exchange resin has a first ion exchange group density, the low-selectivity alkali metal ion exchange resin has a second ion exchange group density, and the first ion exchange group density is greater than the second ion exchange group density.

[0016] In one embodiment, the resin matrix of the highly selective alkali metal ion exchange resin has a first crosslinking degree, the low selective alkali metal ion exchange resin has a second crosslinking degree, and the first crosslinking degree is higher than the second crosslinking degree.

[0017] In one embodiment, the resin matrix of the highly selective alkali metal ion exchange resin contains sulfonic acid groups, and the exchange capacity of the highly selective alkali metal ion exchange resin is above 4.5 mmol / g.

[0018] In one embodiment, the highly selective alkali metal ion exchange resin is a potassium ion exchange resin, and the low selective alkali metal ion exchange resin is a sodium ion exchange resin; the total volume of the liquid containing the impurity ions flowing through the ion exchange unit is above 150 L.

[0019] In one embodiment, a separation unit is arranged between the highly selective alkali metal ion exchange resin and the low selective alkali metal ion exchange resin.

[0020] In one embodiment, when the total volume of the liquid containing the impurity ions flowing through the ion exchange unit is 75 L, the content of the highly selective alkali metal ions in the treated liquid is above 50% of the initial content.

[0021] The second technical solution provided by the present invention is as follows:

[0022] An ion exchange module, the ion exchange module includes a plurality of ion exchange units arranged along the water flow direction;

[0023] The ion exchange unit includes:

[0024] A highly selective alkali metal ion exchange resin and a low selective alkali metal ion exchange resin;

[0025] It allows the impurity ions to sequentially pass through the highly selective alkali metal ion exchange resin and the low selective alkali metal ion exchange resin along the water flow direction, so that the effluent contains highly selective alkali metal ions and low selective alkali metal ions capable of exchanging with the impurity ions, and part of the highly selective alkali metal ions are replaced and intercepted when entering the low selective alkali metal ion exchange resin;

[0026] The highly selective alkali metal ion exchange resins and the low selective alkali metal ion exchange resins in a plurality of the ion exchange units are arranged according to a fixed ratio along the water flow direction.

[0027] The third technical solution provided by the present invention is as follows:

[0028] An ion exchange device, comprising:

[0029] A raw water storage unit for containing the liquid to be treated, where the liquid to be treated is composed of a liquid containing impurity ions;

[0030] A soft water collection unit for containing the treated liquid, where the treated liquid contains exchange ions composed of ions capable of exchanging with the impurity ions; and

[0031] An ion exchange unit, which includes a highly selective alkali metal ion exchange resin and a lowly selective alkali metal ion exchange resin, and allows the impurity ions to sequentially pass through the highly selective alkali metal ion exchange resin and the lowly selective alkali metal ion exchange resin along the water flow direction, so that the effluent contains highly selective alkali metal ions and lowly selective alkali metal ions capable of exchanging with the impurity ions, and part of the highly selective alkali metal ions are displaced and intercepted when entering the lowly selective alkali metal ion exchange resin.

[0032] Based on the above, compared with the prior art, the ion exchange unit provided by the present invention can effectively control the release of highly selective alkali metal ions through the layer - arranged highly selective alkali metal ion exchange resin and lowly selective alkali metal ion exchange resin, and significantly extend the service life.

[0033] Other features and beneficial effects of the present invention will be described in the subsequent specification, and part of them will become obvious from the specification or be understood by implementing the present invention. The objectives and other beneficial effects of the present invention can be achieved and obtained through the structures specifically pointed out in the specification, claims, and drawings. Brief Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following - described drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings; in the following description, regarding the positional relationship in the drawings, unless otherwise specified, the directions of the components shown in the drawings are used as the reference.

[0035] Figure 1 Shown is a schematic structural diagram of an ion exchange unit provided by an embodiment of the present invention;

[0036] Figure 2 Shown is a schematic structural diagram of an ion exchange device provided by an embodiment of the present invention;

[0037] Figure 3 Shown is a schematic structural diagram of the ion exchange unit provided in Embodiment 1 of the present invention;

[0038] Figure 4Shown is a schematic structural diagram of the ion exchange unit provided by Comparative Example 1 of the present invention;

[0039] Figure 5 Shown is a schematic structural diagram of the ion exchange unit provided by Comparative Example 2 of the present invention;

[0040] Figure 6 Shown is a schematic structural diagram of the ion exchange unit provided by Comparative Example 3 of the present invention.

[0041] Reference numerals:

[0042] 1, raw water storage unit; 2, ion exchange unit; 21, highly selective alkali metal ion exchange resin; 22, low-selectivity alkali metal ion exchange resin; 23, separation unit; 3, softened water collection unit. Detailed implementation manners

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention; the technical features designed in different implementation manners of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0044] In the description of the present invention, it should be noted that all terms (including technical terms and scientific terms) used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the technical field to which the present invention pertains, and should not be construed as a limitation of the present invention; it should be further understood that the terms used in the present invention should be understood as having meanings consistent with their meanings in the context of this specification and the relevant art, and should not be understood in an idealized or overly formal sense, unless clearly defined as such in the present invention.

[0045] Please refer to the accompanying drawings to describe an embodiment of the ion exchange unit of the present invention. Figure 1 A schematic structural diagram of the ion exchange unit of this embodiment is schematically shown. This ion exchange unit can be configured, for example, in a semiconductor device chip manufacturing factory, a pharmaceutical manufacturing factory, etc., which are arranged in the pure water supply path, or in softening industrial water, producing pure water, and purifying, for example, drinking water and vehicle cooling water, etc., to remove certain impurity ions, increase some beneficial ions, and achieve the functions of purifying and mineralizing water.

[0046] In this embodiment, the water (also referred to as raw water) provided to the ion exchange unit is, for example, tap water or clean water from which suspended matter and impurities have been removed in advance by a filter or activated carbon. In addition, the water contains ions other than hydrogen ions and hydroxide ions derived from water molecules. The ion exchange unit of this embodiment removes impurity ions other than ions derived from water molecules from the provided water by exchange, and adds elements that are beneficial to the human body, thereby purifying and mineralizing the water.

[0047] Please refer to Figure 1 In this embodiment, the ion exchange unit 2 includes: a high-selectivity alkali metal ion exchange resin 21, a low-selectivity alkali metal ion exchange resin 22, and a separation unit 23 disposed between the high-selectivity alkali metal ion exchange resin and the low-selectivity alkali metal ion exchange resin; for example, in the implementation of this embodiment, the high-selectivity alkali metal ion exchange resin 21 is a potassium ion exchange resin, and the low-selectivity alkali metal ion exchange resin 22 is a sodium ion exchange resin; it allows impurity ions such as calcium ions (Ca 2+ ), magnesium ion (Mg 2+ ) etc. are sequentially passed through a high-selectivity alkali metal ion exchange resin 21 (the high-selectivity alkali metal ion exchange resin 21 schematically used in this embodiment is a potassium ion exchange resin) and a low-selectivity alkali metal ion exchange resin 21 (the low-selectivity alkali metal ion exchange resin 21 schematically used in this embodiment is a sodium ion exchange resin) along the flow direction of the water channel, so that the effluent contains impurities such as calcium ions (Ca 2+ ), magnesium ion (Mg 2+ ) and other highly selective alkali metal ions (such as K + ) and less selective alkali metal ions (such as Na + ) and some of the highly selective alkali metal ions (such as K + ) is replaced and retained in the low-selectivity alkali metal ion exchange resin 22; based on the exchange coefficient of the ion exchange resin / membrane, that is, the low-selectivity alkali metal ions (such as Na + ) for highly selective alkali metal ions (such as K + ) Usually slightly lower than highly selective alkali metal ions (such as K + ) for low selectivity alkali metal ions (such as Na + ) exchange coefficient, which means that under the same operating conditions, low selectivity alkali metal ions (such as Na + ) for highly selective alkali metal ions (such as K + ) is replaced slowly; highly selective alkali metal ions (such as K +) will not be quickly "replaced" to saturation or rapidly depleted. Therefore, in this application, a layered structure of a highly selective alkali metal ion exchange resin / a low-selectivity alkali metal ion exchange resin is adopted to control the order of ion exchange in the water flow, so that divalent ions in the water first enter the highly selective alkali metal ion exchange resin (K ion exchange resin) and are displaced, and the displaced highly selective alkali metal ions (such as K + ) enter the low-selectivity alkali metal ion exchange resin (Na ion exchange resin), which causes the low-selectivity alkali metal ion exchange resin (Na ion exchange resin) to displace the highly selective alkali metal ions (such as K + ), thereby realizing that the highly selective alkali metal (such as K) element is retained in the low-selectivity alkali metal ion exchange resin, thus slowing down the overall release rate of the highly selective alkali metal ions (such as K + ), and further extending the overall life of the highly selective alkali metal ions. It is also worth noting that since the low-selectivity alkali metal ion exchange resin (Na ion exchange resin) is not on the outermost layer of the ion exchange, the consumption of Na ions in the resin is significantly reduced, thus realizing the synchronous slow release of K ions and Na ions;

[0048] Furthermore, the separation unit 23 is arranged between the highly selective alkali metal ion exchange resin 21 and the low-selectivity alkali metal ion exchange resin 22. In this way, on the one hand, it plays a role in preventing resin mixing and preventing the occurrence of interlayer mixing caused by water flow disturbance, and the grid pore design can guide the water flow to pass through evenly, avoiding the "channeling effect" that causes the exchange efficiency to decrease due to too fast local water flow; on the other hand, it can reduce the abrasion of the resin particles by the water flow impact and balance the water flow resistance of the highly selective alkali metal ion exchange resin (K layer) and the low-selectivity alkali metal ion exchange resin (Na layer) through porosity adjustment; the material of the separation unit 23 includes but is not limited to polypropylene (PP), polytetrafluoroethylene (PTFE), stainless steel, etc.; and the grid structure of the separation unit 23 includes but is not limited to woven grid, punched plate grid or multi-layer composite structure.

[0049] In a preferred embodiment of the present invention, the thickness of the highly selective alkali metal ion exchange resin (in this embodiment, taking the K ion exchange resin as an example, hereinafter referred to as the K layer) is greater than that of the low-selectivity alkali metal ion exchange resin (in this embodiment, taking the Na ion exchange resin as an example, hereinafter referred to as the Na layer). For example, in the structure design with a uniform layer thickness, its defect stems from the irreversibility of the ion exchange path and the lack of an interlayer coordination mechanism. When the water flow first passes through the K layer, the K layer resin will quickly release a large amount of K + , resulting in too high a concentration of K + in the water flow entering the Na layer subsequently (much higher than the concentration of Na + ), and the high K +The concentration will significantly inhibit Na in the Na layer + from regenerating the K resin, resulting in premature saturation of the Na layer and a significant reduction in the regeneration efficiency. Therefore, in the embodiments of the present invention, a thick K layer and thin Na layer structure design is adopted. On the one hand, it provides sufficient K + reserves, delays depletion, and makes the Na layer more focused on regenerating the K layer, reducing interference from other ions, thereby achieving the slow release of K + and extending the service life of the K / Na ion exchange unit; moreover, the thickening of the K layer can also extend the residence time of the liquid containing impurity ions in the resin layer and improve the ion exchange efficiency.

[0050] In a preferred embodiment of the present invention, the content of the highly selective alkali metal ions in the highly selective alkali metal ion exchange resin is greater than the content of the lowly selective alkali metal ions in the lowly selective alkali metal ion exchange resin; more preferably, the ratio of the content of the highly selective alkali metal ions in the highly selective alkali metal ion exchange resin to the content of the lowly selective alkali metal ions in the lowly selective alkali metal ion exchange resin is greater than 1 and less than or equal to 2, so as to ensure that the release amount of the highly selective alkali metal ions in the highly selective alkali metal ion exchange resin is greater than the release amount of the lowly selective alkali metal ions in the lowly selective alkali metal ion exchange resin; more preferably, the ratio of the content of the highly selective alkali metal ions in the highly selective alkali metal ion exchange resin to the content of the lowly selective alkali metal ions in the lowly selective alkali metal ion exchange resin is 2:1. At these ratios, when the total volume of the liquid containing the impurity ions flowing through the ion exchange unit is 75 L, the content of the highly selective alkali metal ions in the treated liquid is more than 50% of the initial content, and when the total volume of the liquid containing the impurity ions flowing through the ion exchange unit is more than 150 L, it can still make the treated liquid contain exchange ions composed of ions capable of exchanging with the impurity ions, especially containing highly selective alkali metal ions (such as K + ).

[0051] In a preferred embodiment of the present invention, the highly selective alkali metal ion exchange resin (in this embodiment, taking the K ion exchange resin as an example, hereinafter referred to as the K layer) has a first ion exchange group density, and the lowly selective alkali metal ion exchange resin (in this embodiment, taking the Na ion exchange resin as an example, hereinafter referred to as the Na layer) has a second ion exchange group density. The first ion exchange group density is greater than the second ion exchange group density. In this way, the group density of the K layer can be increased, and the K reserve per unit thickness can be increased. At the same time, the low-density Na layer slowly releases Na + + ​, continuously regenerate the active sites in the K layer, avoid rapid depletion. Further, in a limited space (such as a filter element), a high-group-density resin can achieve the same exchange capacity with a thinner layer thickness, reducing the system pressure drop.

[0052] In a preferred embodiment of the present invention, the crosslinking degree of the resin matrix of the high-selectivity alkali metal ion exchange resin decreases in a gradient from the outer layer to the inner layer. Thus, for the high crosslinking degree of the outer layer, it slows down the diffusion rate of K + , avoids the initial explosive release and has strong swelling property, reduces the resin fragmentation caused by water flow scouring, while the lower crosslinking degree of the inner layer results in an increased pore size, which can store more K + and maintains the slow-release ability in the later stage. At the same time, more K + can promote the replacement of the Na layer to intercept K + .

[0053] In a more preferred embodiment of the present invention, the resin matrix of the high-selectivity alkali metal ion exchange resin has a first crosslinking degree, the low-selectivity alkali metal ion exchange resin has a second crosslinking degree, the second crosslinking degree is generally in the range of 6% - 10%, and the first crosslinking degree is higher than the second crosslinking degree. Thus, the low crosslinking degree of the low-selectivity alkali metal ion exchange resin makes the diffusion of ions easier, thereby improving the exchange speed and exchange capacity, and can exchange more high-selectivity alkali metal ions (such as K + ), and then can more effectively intercept high-selectivity alkali metal ions (such as K + ), achieving a slow-release effect.

[0054] In a preferred embodiment of the present invention, the resin matrix of the high-selectivity alkali metal ion exchange resin contains sulfonic acid groups, which can effectively exchange with potassium ions; more preferably, the exchange capacity of the high-selectivity alkali metal ion exchange resin is above 4.5 mmol / g.

[0055] Another embodiment of the present invention provides an ion exchange module, which includes a plurality of ion exchange units 2 arranged along the water flow direction;

[0056] The ion exchange unit includes: a high-selectivity alkali metal ion exchange resin 21 and a low-selectivity alkali metal ion exchange resin 22;

[0057] It allows impurity ions to sequentially pass through the high-selectivity alkali metal ion exchange resin 21 and the low-selectivity alkali metal ion exchange resin 22 along the water flow direction, so that the effluent contains high-selectivity alkali metal ions and low-selectivity alkali metal ions that can exchange with the impurity ions, and part of the high-selectivity alkali metal ions are replaced and intercepted when entering the low-selectivity alkali metal ion exchange resin 22;

[0058] A number of the highly selective alkali metal ion exchange resins 21 and the low-selectivity alkali metal ion exchange resins 22 in the ion exchange units 2 are arranged in a fixed proportion along the water flow direction to reduce the production and maintenance costs of the filter element, and the maintenance of the single-proportion filter element structure is simpler and the regeneration cycle is more stable. Moreover, the design of the fixed proportion (such as the mass ratio of potassium ion content to sodium ion content being 2:1) in the preferred embodiment of the present invention can already ensure a sufficiently long service life, and the treated water volume can also meet the requirements.

[0059] A number of the ion exchange units 2 are arranged in an asymmetric proportion gradient with a gradually decreasing proportion of the highly selective alkali metal ion exchange resin along the water flow direction. For example, three ion release units 2a, 2b, and 2c are arranged along the water flow direction. Among them, the first ion release unit 2a is located at the water inlet end, and the volume ratio of its K resin to Na resin is 9:1. The second ion release unit 2b is located in the middle, and the volume ratio of K resin to Na resin is 6:4. The third ion release unit 2c is located at the water outlet end, and the volume ratio of K resin to Na resin is 3:7, thus forming a high-K + release area (the first ion release unit 2a), a buffer exchange area (the second ion release unit 2b), and a Na + dominant regeneration area (the third ion release unit 2c); thus, this embodiment is based on a physically divided independent multi-layer structure and each layer is an integral ion exchange membrane, and different Na / K content ratios or different exchange group distributions are provided between the layers. In this way, the slow release of K can be better optimized + and its release life can be extended.

[0060] Please refer to Figure 2 , and another embodiment of the present invention provides an ion exchange device, including:

[0061] A raw water storage unit 1 for accommodating the liquid to be treated, and the liquid to be treated is composed of a liquid containing impurity ions;

[0062] A soft water collection unit 3 for accommodating the treated liquid, and the treated liquid contains exchange ions composed of ions capable of exchanging with the impurity ions; and

[0063] An ion exchange unit 2, the ion exchange unit 2 includes a highly selective alkali metal ion exchange resin 21 and a low-selectivity alkali metal ion exchange resin 22, which allow the impurity ions to sequentially pass through the highly selective alkali metal ion exchange resin 21 and the low-selectivity alkali metal ion exchange resin 22 along the water flow direction, so that the effluent contains highly selective alkali metal ions and low-selectivity alkali metal ions capable of exchanging with the impurity ions, and part of the highly selective alkali metal ions are displaced and intercepted when entering the low-selectivity alkali metal ion exchange resin 22.

[0064] When the total volume of the liquid containing the impurity ions flowing through the ion exchange device is 75 L, the content of highly selective alkali metal ions in the treated liquid is more than 50% of the initial value.

[0065] The experimental results showing the technical advantages of the present invention will be described below using examples and comparative examples.

[0066] Example 1

[0067] Prepare an ion exchange unit as Figure 3 shown. The ion exchange unit sequentially includes 80 g of potassium ion exchange resin (schematically represented by 211 in the figure), a grid (schematically represented by 231 in the figure), and 40 g of sodium ion exchange resin (schematically represented by 221 in the figure) along the water flow direction; wherein, the thickness ratio of the potassium ion exchange resin to the sodium ion exchange resin is 2:1.

[0068] Comparative Example 1

[0069] Prepare an ion exchange unit as Figure 4 shown. The ion exchange unit sequentially includes 40 g of sodium ion exchange resin (schematically represented by 222 in the figure), a grid (schematically represented by 232 in the figure), and 80 g of potassium ion exchange resin (schematically represented by 212 in the figure) along the water flow direction; wherein, the thickness ratio of the potassium ion exchange resin to the sodium ion exchange resin is 2:1.

[0070] Comparative Example 2

[0071] Prepare an ion exchange unit as Figure 5 shown. The ion exchange unit includes 80 g of potassium ion exchange resin and 40 g of sodium ion exchange resin particles (schematically represented by Na particles) dispersed in the potassium ion exchange resin (schematically represented by 213 in the figure).

[0072] Comparative Example 3

[0073] Prepare an ion exchange unit as Figure 6 described. The ion exchange unit is composed only of 120 g of potassium ion exchange resin (schematically represented by 214 in the figure).

[0074] Test the above ion exchange units at the same flow rate and with the same liquid to be treated, and detect the content of K + in the treated liquid. The results are shown in the following table:

[0075] Table 1

[0076]

[0077]

[0078] Table 2

[0079] <![CDATA[Total flow rate (Na + content)]]> 0L (ppm) 75L (ppm) 150L (ppm) Example 1 1 5 8 Comparative Example 1 39 23 8 Comparative Example 2 7 7 0 Comparative Example 3 0 0 0

[0080] It can be seen that by using the ion exchange unit provided in the embodiment of the present invention, after treating 75 L of the liquid to be treated, the K content in the treated liquid can still remain at 58.6% (more than 50%) of the initial value, and after treating 150 L of the liquid to be treated, 7 ppm of K content can still be detected in the treated liquid. Moreover, the emission amount of Na is stably within a relatively low value range, which helps to extend the service life of the water-related equipment and broaden the application range of the effluent. + It can be seen that by using the ion exchange unit provided in the embodiment of the present invention, after treating 75 L of the liquid to be treated, the K content in the treated liquid can still remain at 58.6% (more than 50%) of the initial value, and after treating 150 L of the liquid to be treated, 7 ppm of K content can still be detected in the treated liquid. Moreover, the emission amount of Na is stably within a relatively low value range, which helps to extend the service life of the water-related equipment and broaden the application range of the effluent. + content. Moreover, + the emission amount of Na is stably within a relatively low value range, which helps to extend the service life of the water-related equipment and broaden the application range of the effluent.

[0081] In addition, those skilled in the art should understand that although there are many problems in the prior art, each embodiment or technical solution of the present invention can be improved only in one or several aspects, and it is not necessary to solve all the technical problems listed in the prior art or the background art at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be regarded as a limitation to that claim.

[0082] Although terms such as raw water storage unit, ion exchange unit, highly selective alkali metal ion exchange resin, low selective alkali metal ion exchange resin, separation unit, soft water collection unit, etc. are used more frequently in this article, the possibility of using other terms is not excluded. Using these terms is only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention; the terms "first", "second", etc. (if any) in the specification, claims and the above drawings of the embodiments of the present invention are used to distinguish similar objects and do not have to be used to describe a specific order or sequence.

[0083] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ion exchange unit, characterized in that, the ion exchange unit comprises: a highly selective alkali metal ion exchange resin and a low-selectivity alkali metal ion exchange resin; it allows impurity ions to sequentially pass through the highly selective alkali metal ion exchange resin and the low-selectivity alkali metal ion exchange resin along the water flow direction, so that the effluent contains highly selective alkali metal ions and low-selectivity alkali metal ions capable of exchanging with the impurity ions, and part of the highly selective alkali metal ions are displaced and intercepted when entering the low-selectivity alkali metal ion exchange resin.

2. The ion exchange unit according to claim 1, characterized in that, the release amount of highly selective alkali metal ions in the highly selective alkali metal ion exchange resin is greater than the release amount of low-selectivity alkali metal ions in the low-selectivity alkali metal ion exchange resin.

3. The ion exchange unit according to claim 2, characterized in that, the thickness of the highly selective alkali metal ion exchange resin is greater than that of the low-selectivity alkali metal ion exchange resin; and / or the highly selective alkali metal ion exchange resin has a first ion exchange group density, the low-selectivity alkali metal ion exchange resin has a second ion exchange group density, and the first ion exchange group density is greater than the second ion exchange group density.

4. The ion exchange unit according to claim 1, characterized in that, the resin matrix of the highly selective alkali metal ion exchange resin has a first crosslinking degree, the low-selectivity alkali metal ion exchange resin has a second crosslinking degree, and the first crosslinking degree is higher than the second crosslinking degree.

5. The ion exchange unit according to claim 1, characterized in that, the resin matrix of the highly selective alkali metal ion exchange resin contains sulfonic acid groups, and the exchange capacity of the highly selective alkali metal ion exchange resin is above 4.5 mmol / g.

6. The ion exchange unit according to claim 1, characterized in that, the highly selective alkali metal ion exchange resin is a potassium ion exchange resin, the low-selectivity alkali metal ion exchange resin is a sodium ion exchange resin; the total volume of the liquid containing the impurity ions flowing through the ion exchange unit is above 150 L.

7. The ion exchange unit according to claim 1, characterized in that, a separation unit is provided between the highly selective alkali metal ion exchange resin and the low-selectivity alkali metal ion exchange resin.

8. The ion exchange unit according to claim 1, characterized in that, when the total volume of the liquid containing the impurity ions flowing through the ion exchange unit is 75 L, the content of highly selective alkali metal ions in the treated liquid is above 50% of the initial content.

9. An ion exchange module, characterized in that, the ion exchange module comprises a plurality of ion exchange units arranged along the water flow direction; the ion exchange unit comprises: a highly selective alkali metal ion exchange resin and a low-selectivity alkali metal ion exchange resin; It allows impurity ions to sequentially pass through a highly selective alkali metal ion exchange resin and a low-selectivity alkali metal ion exchange resin along the water flow direction, so that the effluent contains highly selective alkali metal ions and low-selectivity alkali metal ions capable of exchanging with the impurity ions, and part of the highly selective alkali metal ions are displaced and intercepted when entering the low-selectivity alkali metal ion exchange resin; The highly selective alkali metal ion exchange resin and the low-selectivity alkali metal ion exchange resin in a number of the ion exchange units are arranged in a fixed proportion along the water flow direction.

10. An ion exchange device, characterized in that, Comprising: A raw water storage unit for accommodating the liquid to be treated, the liquid to be treated being composed of a liquid containing impurity ions; A soft water collection unit for accommodating the treated liquid, the treated liquid containing exchange ions composed of ions capable of exchanging with the impurity ions; and An ion exchange unit, the ion exchange unit including a highly selective alkali metal ion exchange resin and a low-selectivity alkali metal ion exchange resin, which allows impurity ions to sequentially pass through the highly selective alkali metal ion exchange resin and the low-selectivity alkali metal ion exchange resin along the water flow direction, so that the effluent contains highly selective alkali metal ions and low-selectivity alkali metal ions capable of exchanging with the impurity ions, and part of the highly selective alkali metal ions are displaced and intercepted when entering the low-selectivity alkali metal ion exchange resin.

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