Continuous walnut kernel boiled liquid polyphenol adsorption and resin regeneration system and process

Abstract

The invention discloses a continuous walnut kernel poached liquid polyphenol adsorption and resin regeneration system and process, and aims at the characteristics of high organic matter concentration, strong biological inhibition and rich high-value walnut polyphenol in poached liquid during walnut poached liquid processing. Comprising a front-end pretreatment unit, a middle-end adsorption unit and a tail-end regeneration unit. The core of the device is that at least five resin columns are adopted in the middle-end adsorption unit, a circulation mode of five-column series adsorption and two-column off-line regeneration is formed through control of a valve group, and precise control is achieved by assistance of an on-line polyphenol detector. And the tail end regeneration unit adopts food-grade ethanol as a resolving agent to efficiently recover polyphenol. The method provided by the invention solves the problems of direct discharge of walnut kernel poached liquid polyphenol, high poached liquid treatment cost and the like in the traditional process, realizes continuous, stable and efficient recovery of walnut polyphenol from high organic poached liquid, and provides innovative technical equipment for waste recycling.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of processing and recycling of high value-added substances of agricultural products, and particularly relates to a continuous walnut kernel water boiling liquid polyphenol adsorption and resin regeneration system and process for high-concentration polyphenol water boiling liquid generated in the walnut kernel processing. BACKGROUND

[0002] During the processing of walnut kernels into food (such as walnut kernels and walnut oil), a large amount of rinsing and soaking water boiling liquid is generated. This type of water boiling liquid not only has extremely high chemical oxygen demand (COD) and biological oxygen demand (BOD), contains a large amount of oil, protein, sugar and organic acid, etc., but also has strong biological inhibition due to the rich polyphenols such as flavonoids and tannic acid. The conventional biochemical method is difficult to handle and has high cost. However, these polyphenols have excellent biological activities such as antioxidant and antibacterial, and have broad application prospects and high economic value in the fields of food, health care products and cosmetics. Treating such water boiling liquid as "waste" directly not only causes serious environmental pressure, but also is a great waste of valuable plant chemical resources.

[0003] The adsorption resin method is considered as an effective means for recovering polyphenols from complex substrates due to its strong selective adsorption capacity and large adsorption capacity for phenolic substances. There are also cases of using resin method to treat relatively clear water boiling liquid or extract of tea, fruits and vegetables in the prior art. However, the walnut kernel water boiling liquid has unique material properties due to its high concentration of oil and protein. The system has poor physical stability and is prone to stratification to form a milky liquid or a floating oil layer after long storage, which fundamentally challenges the continuous adsorption process which relies on stable feeding, and easily causes uneven flow distribution in the resin column, channeling short circuit, and aggravation of oil phase wrapping pollution of resin particles, thereby facing serious problems such as unstable system operation and rapid deactivation of resin when directly using the prior art: (1) Heavy pretreatment load: conventional filtration cannot effectively break the emulsion or separate the floating oil, and a more efficient and more targeted pretreatment unit (such as a precise demulsification and centrifugal separation device) must be configured to meet the feeding requirements of the subsequent adsorption unit, which significantly increases the system complexity and investment cost; (2) Low mass transfer efficiency and adsorption capacity decay: uneven flow field and channeling short circuit cause a large amount of resin bed to fail to participate in effective adsorption, and the theoretical adsorption capacity of the resin cannot be fully utilized; at the same time, the wrapping layer formed by the oil phase on the surface of the resin seriously hinders the diffusion and mass transfer of polyphenol molecules into the pore channel, resulting in a dynamic adsorption capacity much lower than the theoretical value; (3) Regeneration difficulties and resin poisoning: Resins deeply contaminated with grease and protein cannot be completely restored to activity by conventional ethanol desorption alone. Contaminants accumulate continuously during repeated operation, which can easily lead to permanent blockage of resin pores and deactivation of adsorption sites, ultimately resulting in the overall scrapping of the resin and a significant increase in operating costs; (4) Low value of resource-based products: If the regeneration and analysis process is not properly controlled, the obtained polyphenol extract generally has a low concentration and high impurity content, which significantly increases the difficulty and cost of subsequent purification and seriously restricts the economic feasibility of resource recovery.

[0004] Therefore, given the characteristics of walnut kernel processing decoction, especially its first systematic development as a new raw material for polyphenol recovery, there is an urgent need to construct an integrated equipment and process that can operate continuously and stably, has strong anti-pollution capabilities, is easy to conduct pilot-scale verification, and can directly obtain high-concentration, high-value polyphenol extract. Breakthroughs in this technology are crucial for promoting the green, circular, and sustainable development of the walnut kernel processing industry. Summary of the Invention

[0005] The summary section of this application is intended to provide a brief overview of the concepts, which will be described in detail in the detailed description section below. This summary section is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0006] To address the problems and shortcomings of existing technologies, the present invention aims to provide a continuous polyphenol adsorption and resin regeneration system and process for walnut kernel decoction. This invention overcomes many deficiencies in the existing technology for treating polyphenols in walnut kernel decoction by organically combining non-metallic materials throughout the process, multi-column series adsorption, and online intelligent regeneration technology. This achieves efficient purification of the decoction while continuously, stably, and with a high yield, recovering walnut polyphenols, thus solving the problems mentioned in the background section.

[0007] To achieve the above objectives, the present invention provides the following technical solution: As a first aspect of this application, the present invention discloses a continuous polyphenol adsorption and resin regeneration system for walnut kernel decoction, comprising a front-end pretreatment unit, a mid-end adsorption unit, and a tail-end regeneration unit connected in sequence. The mid-end adsorption unit includes at least two adsorption lines arranged in parallel, and each adsorption line further includes multiple resin columns connected in series via valves. Each resin column is filled with adsorption resin material, and at least two of the multiple resin columns include spare resin columns. The walnut kernel decoction is connected to the front-end pretreatment unit for filtration to obtain a clarified walnut kernel decoction. The clarified walnut kernel decoction is then input into the mid-end adsorption unit, where it adsorbs walnut polyphenol components through the resin columns before being sent to the tail-end regeneration unit. The tail-end regeneration unit analyzes and recovers the adsorbed walnut polyphenol components and rinses the analyzed resin columns for subsequent use.

[0008] Preferably, the pretreatment unit includes a water-boiling liquid buffer tank, a demulsification and oil removal device, an isoelectric point sedimentation device, a feed pump, and a security filter connected in sequence via pipelines. The walnut kernel water-boiling liquid is fed into the water-boiling liquid buffer tank to mitigate fluctuations in water volume and quality. The demulsification and oil removal device separates free oils and emulsions from the walnut kernel water-boiling liquid. The isoelectric point sedimentation device adjusts the isoelectric point range to promote the full coagulation and precipitation of soluble proteins and colloidal substances. The feed pump delivers materials and provides stable pressure. Finally, the security filter traps fine pectin, fiber, and other suspended solids in the walnut kernel water-boiling liquid.

[0009] Preferably, the tail-end regeneration unit includes an eluent storage tank group, a regeneration pump, and a receiving tank group. The eluent storage tank group includes an ethanol storage tank and a water storage tank, and the receiving tank group includes an enrichment recovery tank and a column wash return water tank. The regeneration pump pumps the ethanol and pure water in the ethanol and water storage tanks into the resin column for eluent analysis and rinsing. The eluent rich in high-purity walnut polyphenols after analysis is directed to flow into the enrichment recovery tank, while the rinsing solution containing residual ethanol after rinsing is directed to flow into the column wash return water tank.

[0010] Preferably, each resin column is connected to an online polyphenol concentration detector via its output pipe. The online polyphenol concentration detector can be an online detection device based on the principle of ultraviolet absorption spectroscopy or fluorescence spectroscopy, used to monitor the concentration of polyphenols in the liquid output from the resin column after adsorption.

[0011] Preferably, the boiling liquid buffer tank, demulsification and oil removal device, isoelectric point precipitation device, resin column, security filter, pipeline and valve are all made of non-metallic materials, which are one or more of unplasticized polyvinyl chloride, polypropylene, polyethylene, polytetrafluoroethylene or fiberglass.

[0012] Preferably, the system is integrated into a movable pulley frame. This integration makes the equipment lightweight and portable, facilitating flexible transfer between processing workshops and laboratories.

[0013] Preferably, the rinsing liquid generated from rinsing the resin column can also be returned to the boiling liquid buffer tank for further treatment, so as to achieve ethanol recovery and scattered discharge of boiling liquid.

[0014] Preferably, the adsorbent resin material inside the resin column is a multi-layer adsorption structure consisting of a molecular gel layer, a core enrichment layer, and a refined capture layer connected sequentially from top to bottom. The molecular gel layer is used to intercept large molecular impurities in the boiled walnut kernel liquid, the core enrichment layer is used to adsorb walnut polyphenols in the boiled walnut kernel liquid, and the refined capture layer is used to capture highly polar and water-soluble small molecules that penetrate the core enrichment layer. The outlet of the resin column is connected to two enrichment liquid recovery tanks and a waste liquid tank through pipe valves and pipelines, respectively. Multiple ethanol storage tanks are provided for storing ethanol of different purities.

[0015] As a second aspect of this application, the present invention also discloses a continuous process for polyphenol adsorption and resin regeneration of walnut kernel decoction, comprising the following steps: Step S1: The walnut kernel decoction produced from the processing of walnut kernels is sent to the front-end pretreatment unit for buffering and filtration, and a clear walnut kernel decoction is output. Step S2: Then, the clarified walnut kernel decoction is sent to the middle adsorption unit to adsorb walnut polyphenols through the adsorption line and then discharged or sent to the tail regeneration unit. Step S3: The concentration of polyphenols in the liquid output from the resin column after adsorption is monitored in real time by an online polyphenol concentration detector on the output pipe of each resin column on the adsorption line, and it is determined whether the resin column has been saturated with adsorption. Step S4: The ethanol desorption agent in the ethanol storage tank of the tail end regeneration unit is pumped into the saturated resin column for desorption through the regeneration pump, and the resulting desorption liquid rich in high-purity walnut polyphenols is guided into the enrichment liquid recovery tank. Step S5: Use the regeneration pump to pump pure water from the pure water tank to the resin column after analysis to rinse away residual ethanol, and guide the rinse solution into the column wash return water tank. Step S6: Set the resin column that has been analyzed and cleaned to a standby state for subsequent use.

[0016] Preferably, when the adsorbent resin material has a multilayer adsorbent structure, the method further includes the following step: Step S401: 5%-15% ethanol is pumped from one of the ethanol storage tanks into the purified capture layer in the saturated resin column by the regeneration pump, and the resulting eluent rich in flavor substances is directed to one of the enrichment recovery tanks. In step S402, 60%-75% ethanol is pumped from another ethanol storage tank into the core enrichment layer inside the resin column for analysis. The resulting eluent, rich in high-purity walnut polyphenols, is then directed to another enrichment recovery tank. In step S403, 75%-95% ethanol is pumped from another ethanol storage tank into the molecular gel layer inside the resin column to remove physically trapped macromolecular impurities and output the regenerated waste liquid to the waste liquid tank.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a continuous polyphenol adsorption and resin regeneration system and process for walnut kernel boiled broth. The system consists of a front-end pretreatment unit, a mid-end adsorption unit, and a rear-end regeneration unit. All components in contact with the boiled broth are made of inert non-metallic materials such as UPVC and PP, fundamentally avoiding corrosion from various organic acids and phenols in the walnut kernel boiled broth. The system is integrated into a wheeled frame, achieving lightweight and mobile pilot-scale equipment. A "five-column series adsorption" mode is adopted. The first column acts as the main adsorption load, the second and third columns form a highly efficient and stable core adsorption zone, significantly extending the system's efficient operating cycle; the fourth and fifth columns play a role in deep purification and ultimate protection, ensuring that the effluent concentration is reduced to an extremely low level and resisting concentration fluctuations by extending the mass transfer path. This not only maximizes the resin adsorption potential but also significantly increases the total treatment capacity. An online polyphenol detector is introduced at the water outlet to detect the penetration signal of walnut polyphenols in real time, providing precise data support for resin column switching. This achieves a leap from "experience-based regeneration" to "precision regeneration," avoiding the loss of effective components or ineffective equipment operation. The integrated regeneration unit uses food-grade ethanol as a desorbent to efficiently desorb saturated resin, directly obtaining a high-concentration walnut polyphenol-ethanol enriched solution. This high-quality solution greatly simplifies subsequent refining processes and enhances the value and economic benefits of the resource-based product. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application.

[0019] In the attached diagram: Figure 1 This is a general block diagram of the continuous walnut kernel decoction polyphenol adsorption and resin regeneration system in an embodiment of the present invention; Figure 2 This is a connection structure diagram of the front-end pretreatment unit in the continuous walnut kernel decoction polyphenol adsorption and resin regeneration system in this embodiment of the invention. Figure 3 This is a connection structure diagram of the mid-end adsorption unit in the continuous walnut kernel decoction polyphenol adsorption and resin regeneration system in an embodiment of the present invention. Figure 4 This is a connection structure diagram of the tail-end regeneration unit in the continuous walnut kernel decoction polyphenol adsorption and resin regeneration system in an embodiment of the present invention. Figure 5 This is a structural diagram of the adsorbed resin material in the resin column of the continuous walnut kernel decoction polyphenol adsorption and resin regeneration system in another embodiment of the present invention. Detailed Implementation

[0020] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0021] It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other.

[0022] Example 1 In this embodiment of the invention, a continuous polyphenol adsorption and resin regeneration system for walnut kernel decoction is disclosed, referring to... Figure 1 As shown, the system includes a front-end pretreatment unit, a mid-end adsorption unit, and a rear-end regeneration unit. Specifically, the front-end pretreatment unit includes a water-boiling liquid buffer tank, a demulsification and oil removal device, an isoelectric point precipitation device, a feed pump, and a security filter, all connected sequentially via pipelines. The mid-end adsorption unit includes at least two adsorption lines arranged in parallel, each containing multiple resin columns connected in series via valves. The rear-end regeneration unit includes a desorbent storage tank, a regeneration pump, and a receiving tank.

[0023] Furthermore, the front-end pretreatment unit is used to process walnut kernel decoctions that are high in oil, protein, and organic acids, referring to... Figure 2As shown, the system includes a water-boiling liquid buffer tank, a demulsification and oil removal device, an isoelectric point sedimentation device, a feed pump, and a security filter, all connected sequentially by pipelines. The water-boiling liquid buffer tank is a 1000L capacity polypropylene (PP) tank used to mitigate fluctuations in water volume and quality. The feed pump, with a flow rate of 200L / h and also made of PP, is used to transport materials and provide stable pressure. The security filter, with a precision of 10μm and also made of PP, is used to effectively trap fine pectin, fibers, and other suspended solids in the water-boiling liquid. The demulsification and oil removal device, also made of PP, has a built-in inclined plate sedimentation unit and is equipped with a dosing system for adding a special demulsifier. Through a demulsification-air flotation coupling process, it preferentially separates free oil and emulsion from the water-boiling liquid. The isoelectric point precipitation device is made of polypropylene (PP) / polyvinyl chloride (PVC) and is equipped with an online pH monitoring and precision dosing system. It is used to precisely control the pH of the boiled water solution to the isoelectric point range of 4.2~4.5, so as to promote the full coagulation and precipitation of soluble proteins and colloidal substances.

[0024] The input end of the boiling liquid buffer tank is connected to the homogenized walnut kernel boiling liquid, and the output end is connected to the inlet of the demulsification and oil removal device. The homogenized walnut kernel boiling liquid is a liquid produced by homogenizing walnut kernels and then subjecting them to boiling and filtration processes. The demulsification and oil removal device preferentially removes oils through physical or chemical demulsification, creating oil-free conditions for subsequent adsorption. The output end of the demulsification and oil removal device is connected to the input end of the isoelectric point precipitation device. The isoelectric point precipitation device is used to precisely control the pH to convert soluble proteins and colloids that easily contaminate the resin into separable solids for targeted removal and simultaneously reduce the organic acid load. The output end of the isoelectric point precipitation device is connected to the input end of the feed pump, which in turn is connected to the input end of the security filter. The security filter is used to trap precipitates and suspended particles generated in the aforementioned steps. The output end of the security filter is connected to the input end of the intermediate adsorption unit to output the clarified walnut kernel boiling liquid after filtering impurities.

[0025] Reference Figure 3As shown, the intermediate adsorption unit includes at least two sets of adsorption lines arranged in parallel. Each set of adsorption lines contains multiple resin columns connected in series via valves, and each resin column is filled with LX-17T type macroporous adsorption resin suitable for the specific adsorption of walnut polyphenols. The resin columns are made of transparent unplasticized polyvinyl chloride (UPVC) or fiberglass, and each resin column is filled with 50L of adsorption resin. Using transparent unplasticized UPVC resin columns makes it easy to observe the resin color change to judge the adsorption and propagation status. Multiple resin columns are connected by unplasticized UPVC pipes. Because unplasticized UPVC has excellent corrosion resistance to most inorganic acid, alkali, and salt solutions, it can operate stably for a long time and avoid pollution and leakage problems caused by pipe corrosion. The valves are manual, pneumatic, or electric diaphragm valves. In the unplasticized UPVC pipes, the diaphragm valves use a flexible diaphragm to start, regulate, or cut off the flow of fluid in the pipes, and can simultaneously achieve complete isolation between the resin columns.

[0026] By switching valves, at least five resin columns can be selected from each adsorption line to form a continuous adsorption path. Each adsorption line also includes at least two spare resin columns for use by the subsequent end-of-line regeneration unit. When in use, the saturated resin columns must be removed from the adsorption path. Simultaneously, the regenerated spare resin columns are connected to the adsorption path to maintain a continuous flow of five resin columns in series. The series sequence of the resin columns follows the flow direction of the walnut kernel decoction, with their adsorption saturation decreasing sequentially, achieving tiered utilization of adsorption capacity and ensuring stable effluent quality. The input end of the adsorption line connects to the output end of the pretreatment unit, while the output end connects to the end-of-line regeneration unit or is directly discharged. Furthermore, each resin column's output pipe on the adsorption line is equipped with an online detector for measuring polyphenol concentration. The online polyphenol concentration detector uses an online detection device based on ultraviolet absorption spectroscopy (such as an online ultraviolet spectrophotometer) or fluorescence spectroscopy, enabling real-time, continuous, and automatic monitoring and measurement of the polyphenol concentration in the liquid output from the resin column after adsorption, thereby achieving precise control and quality assurance of the adsorption process.

[0027] Reference Figure 4 As shown, the input end of the tail-end regeneration unit is connected to the output end of the resin column in the mid-end adsorption unit. The tail-end regeneration unit includes a desorbent storage tank group, a regeneration pump, and a receiving tank group. The desorbent storage tank group includes an ethanol storage tank and a water storage tank. The receiving tank group includes an enrichment recovery tank and a column wash return water tank. The receiving tank group, the desorbent storage tank group, and the regeneration pump are all controlled by valves. The ethanol storage tank in the desorbent storage tank group contains a food-grade ethanol aqueous solution with a mass concentration of 60%~75%. This concentration range has the optimal desorption efficiency and economic benefits for walnut polyphenols.

[0028] Ethanol from the desorbent storage tank is pumped into the saturated resin column at a specific flow rate by the regeneration pump. The regeneration pump is not merely a simple delivery pump; it delivers ethanol and pure water to the resin column in the intermediate adsorption unit at the correct pressure, precise flow rate, and stable condition, ensuring the continuous and stable operation of the entire regeneration system. The dark-colored desorbent solution, rich in high-purity walnut polyphenols, flows through the resin column outlet into the guide enrichment recovery tank for storage as a high-value raw material for subsequent use. After desorption is complete, the resin column is flushed sequentially with pure water in both forward and reverse directions until the effluent is clear, indicating that resin regeneration has been completed and desorbed. Flushing the resin column removes residual ethanol, completing regeneration, and simultaneously puts the desorbed and cleaned resin column into standby mode. The wash water generated from flushing the resin column is directed to the column wash return tank for storage. Additionally, the wash water generated from flushing the resin column can be returned to the water boiling buffer tank in the front-end pretreatment unit for further treatment, thereby achieving ethanol recovery and decentralized discharge of the water boiling solution.

[0029] Furthermore, the entire continuous polyphenol adsorption and resin regeneration system for walnut kernel decoction can be integrated into a movable wheeled frame. This integration makes the equipment lightweight and portable. The frame is made of aluminum alloy and equipped with swivel casters with brakes, facilitating flexible transport between the processing workshop and the laboratory.

[0030] In this embodiment, a continuous process for polyphenol adsorption and resin regeneration of walnut kernel decoction is also disclosed, which specifically includes the following steps: Step S1: The walnut kernel decoction produced from the processing of walnut kernels is sent to the front-end pretreatment unit for buffering and filtration, and a clear walnut kernel decoction is output. Step S2: Then, the clarified walnut kernel decoction is sent to the intermediate adsorption unit to adsorb walnut polyphenols through the adsorption line and then discharged or sent to the tail regeneration unit. Step S3: The concentration of polyphenols in the liquid output from the resin column after adsorption is monitored in real time by an online polyphenol concentration detector on the output pipe of each resin column on the adsorption line, and it is determined whether the resin column has been saturated with adsorption. Step S4: The ethanol desorption agent in the ethanol storage tank of the tail end regeneration unit is pumped into the saturated resin column for desorption through the regeneration pump, and the desorption liquid rich in high-purity walnut polyphenols is guided into the enrichment liquid recovery tank. Step S5: Use a regeneration pump to pump pure water from the pure water tank to the purified resin column to rinse away residual ethanol, and then guide the rinse solution into the column wash return tank. Step S6: Set the resin column that has been analyzed and cleaned to a standby state for subsequent use.

[0031] Specifically, taking a set of adsorption lines with 7 resin columns as an example, refer to... Figure 3 and Figure 4 Initially, resin columns #1, #2, #3, #4, and #5 are connected in series to form a complete adsorption pathway, while resin columns #6 and #7 serve as backup resin columns. Here, backup resin columns refer to those that have already been regenerated. During adsorption, for the pretreated boiled water broth containing walnut kernels with a COD of tens of thousands of mg / L and a polyphenol concentration of approximately 15 g / L, the system employs two parallel adsorption lines. The boiled water broth on each line flows sequentially through five adsorption resin columns (#1 → #2 → #3 → #4 → #5) for stepwise adsorption, gradually removing pollutants and efficiently recovering polyphenols. To ensure effluent quality, the system is equipped with an online UV spectrophotometer at the output of the last column (#5) for real-time monitoring. This serves as a core monitoring point to determine in real time whether the adsorbed resin column is saturated and provides crucial signals for switching and regenerating saturated resin columns. When the switching is triggered, the system will automatically trigger a switching signal when the absorbance value of the water effluent from the last column (#5) rises to the set threshold (corresponding to a polyphenol concentration of about 0.05 g / L, i.e. the economic breakthrough point).

[0032] When the online UV spectrophotometer determines that the first column (#1) and the second column (#2) are in a state of adsorption saturation and near saturation, respectively, the saturated first column (#1) and the near-saturated second column (#2) are cut out of the adsorption pathway together, ready for regeneration. After cutting out, the original #3→#4→#5 resin columns are moved forward sequentially to form the new #1→#2→#3 resin column sequence. The regenerated spare columns #6 and #7 are then connected sequentially to form the new #4 and #5 resin columns, respectively, thus completing the system reconstruction and restoring the series adsorption of the five resin columns. This "dual-column replacement, forward shifting and replacement" mode can significantly improve resin utilization efficiency and system operating economy while ensuring processing continuity.

[0033] Next, the regeneration pump is started, pumping 70% food-grade ethanol at a specific flow rate into the cut-out #1 and #2 resin columns for analysis, in the order of #1 → #2. The dark-colored analysis liquid, rich in walnut polyphenols, flows into the concentrate recovery tank as a high-value raw material for storage, with a post-analysis concentration exceeding 50 g / L. After analysis, pure water is pumped into the #1 and #2 resin columns using the regeneration pump, and the #1 and #2 resin columns are sequentially flushed in both forward and reverse directions until the effluent is clear, indicating that regeneration is complete. At this point, the regenerated #1 and #2 resin columns are switched to standby status, awaiting the next cycle. This continuous walnut kernel decoction polyphenol adsorption and resin regeneration system operates cyclically according to this rule, completing the rolling update of the adsorption chain with each switch through a mechanism of "saturation offline, step-by-step replenishment, and standby replacement," thereby achieving continuous production and resource recovery.

[0034] Example 2 The difference between Example 2 and Example 1 lies in the different adsorbent resin material within the resin column. In this example, the adsorbent resin material is not a single material, but rather a three-layer structure consisting of a molecular gel layer, a core enrichment layer, and a refined capture layer, as described above. Figure 5 As shown, each resin layer is specifically designed to capture a particular type of substance, achieving targeted adsorption and significantly reducing interference from non-target substances. A perforated sieve plate is placed between the layers, and an inert, chemically stable spacer is laid on top of the sieve plate. The perforated sieve plate effectively prevents the resin media of different particle sizes and densities from mixing due to liquid flow impact or backflow during regeneration, while the spacer ensures unobstructed flow, allowing the liquid to smoothly and uniformly enter the next resin layer.

[0035] The top molecular gel layer consists of macroporous silica gel, porous polymer microspheres, or gel filtration media with a specific molecular weight cutoff. This layer primarily relies on size exclusion effect; its precisely controlled pore size allows small molecules such as polyphenols, nucleotides, and amino acids to pass through, while directly intercepting large molecules like proteins, starches, plant colloids, and pigment polymers without clogging, significantly increasing the subsequent polyphenol adsorption capacity. This molecular gel layer is a physical sieving process, making it less prone to contamination and easy to backwash and regenerate. The middle core enrichment layer is composed of weakly polar or moderately polar macroporous adsorption resins, such as AB-8, HPD-400, or XDA-8. Its surface chemistry and pore size distribution are highly compatible with the molecular structure and polarity of polyphenols such as flavonoids and phenolic acids. After removing most interferences at the top layer, the core enrichment layer can efficiently and specifically adsorb polyphenols from walnut kernel decoction. Because competing macromolecular impurities have been removed, both the static and dynamic adsorption capacities for polyphenols are close to the theoretical maximum. The bottom-layer refining and capture layer utilizes polar macroporous adsorption resins, such as NKA-II or HPD-600. This layer captures highly polar, water-soluble small molecules, such as free amino acids, small peptides, and sugars, that penetrate the core enrichment layer resin, preventing impurities like amino acids and sugars from contaminating the polyphenol product. This ensures that valuable umami and sweet components are not wasted in subsequent analysis and can be further processed as process tailings for other uses, maximizing resource utilization.

[0036] Simultaneously, we have configured three ethanol storage tanks in the eluent storage tank group to store ethanol of different concentrations: 5%-15%, 60%-75%, and 75%-95%. Correspondingly, there are two enrichment liquid recovery tanks and one waste liquid tank. The two enrichment liquid recovery tanks are used to recover the eluent from the 5%-15% and 60%-75% concentrations, respectively, while the waste liquid tank is used to recover the waste liquid from the 75%-95% concentration ethanol eluent. Although referred to as waste liquid here, it can be further processed as process tailings for other uses. Specifically, pipeline valves are connected to the resin column's outlet, and these valves are connected to the two enrichment liquid recovery tanks and the waste liquid tank via unplasticized UPVC pipes.

[0037] Since the adsorbent resin material inside the resin column has been replaced, the corresponding process will also change. Here, we adopt the gradient analysis method, and the specific steps are as follows: Step S401: 5%-15% ethanol is pumped from one of the ethanol storage tanks into the purified capture layer in the saturated resin column by a regeneration pump, and the resulting eluent rich in flavor substances is directed to one of the enriched liquid recovery tanks. In step S402, 60%-75% ethanol is pumped from another ethanol storage tank into the core enrichment layer inside the resin column for analysis. The resulting eluent, rich in high-purity walnut polyphenols, is then directed to another enrichment recovery tank. In step S403, 75%-95% ethanol is pumped from another ethanol storage tank into the molecular gel layer inside the resin column to remove large molecular impurities that have been physically trapped, and the regenerated waste liquid is output to the waste liquid tank.

[0038] Specifically, 5%-15% ethanol is pumped into the refined capture layer of the saturated resin column via a regeneration pump. The resulting eluent, rich in umami flavor, is directed to one of the enrichment recovery tanks. The polar macroporous adsorption resin in the refined capture layer has a strong adsorption capacity for highly water-soluble substances. Using low-concentration ethanol utilizes the "like dissolves like" principle to gently desorb these highly polar substances, while avoiding premature elution of polyphenols, which have stronger adsorption capacity. Next, 60%-75% ethanol is pumped into the core enrichment layer of the resin column for further analysis, resulting in a high-purity polyphenol eluent directed to another enrichment recovery tank. Since the refined capture layer has already been analyzed, eluting the core enrichment layer with 60%-75% ethanol at this stage yields an eluent rich in high-purity walnut polyphenols, which will not mix with the flavor substances at the bottom. Finally, 75%-95% ethanol is pumped into the molecular gel layer of the resin column to remove physically trapped large molecular impurities, which are then discharged to the waste liquid tank. High concentrations of ethanol can effectively dissolve trapped organic macromolecular impurities such as proteins and pigments.

[0039] All technologies not described in detail in this invention are existing technologies. The above descriptions are merely some preferred embodiments of this disclosure and explanations of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in the embodiments of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalent features without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in the embodiments of this disclosure.

Claims

1. A continuous polyphenol adsorption and resin regeneration system for walnut kernel decoction, characterized in that: The system includes a front-end pretreatment unit, a mid-end adsorption unit, and a rear-end regeneration unit connected in sequence. The mid-end adsorption unit includes at least two adsorption lines arranged in parallel. Each adsorption line also includes multiple resin columns connected in series via valves. Each resin column is filled with adsorption resin material, and at least two of the multiple resin columns are spare resin columns. A decoction of walnut kernels is connected to the front-end pretreatment unit to filter out a clear decoction of walnut kernels. The clear decoction of walnut kernels is then input into the mid-end adsorption unit, where it adsorbs the walnut polyphenols within the resin columns before being sent to the rear-end regeneration unit. The rear-end regeneration unit analyzes and recovers the adsorbed walnut polyphenols and rinses the analyzed resin columns for subsequent use.

2. The continuous polyphenol adsorption and resin regeneration system for walnut kernel decoction according to claim 1, characterized in that: The pretreatment unit includes a water-boiling liquid buffer tank, a demulsification and oil removal device, an isoelectric point sedimentation device, a feed pump, and a security filter, all connected sequentially by pipelines. The walnut kernel water-boiling liquid is fed into the water-boiling liquid buffer tank to mitigate fluctuations in water volume and quality. The demulsification and oil removal device separates free oils and emulsions from the walnut kernel water-boiling liquid. The isoelectric point sedimentation device adjusts the isoelectric point range to promote the full coagulation and precipitation of soluble proteins and colloidal substances. The feed pump delivers materials and provides stable pressure. Finally, the security filter traps fine pectin, fiber, and other suspended solids in the walnut kernel water-boiling liquid.

3. The continuous polyphenol adsorption and resin regeneration system for walnut kernel decoction according to claim 2, characterized in that: The tail-end regeneration unit includes an eluent storage tank group, a regeneration pump, and a receiving tank group. The eluent storage tank group includes an ethanol storage tank and a water storage tank. The receiving tank group includes an enrichment recovery tank and a column wash return water tank. The regeneration pump pumps the ethanol and pure water in the ethanol and water storage tanks into the resin column for eluent analysis and rinsing. The eluent rich in high-purity walnut polyphenols after analysis is directed to flow into the enrichment recovery tank, while the rinsing solution containing residual ethanol after rinsing is directed to flow into the column wash return water tank.

4. The continuous polyphenol adsorption and resin regeneration system for walnut kernel decoction according to claim 3, characterized in that: Each resin column is connected to an online polyphenol concentration detector via its output pipe. The online polyphenol concentration detector can be an online detection device based on the principle of ultraviolet absorption spectroscopy or fluorescence spectroscopy, used to monitor the concentration of polyphenols in the liquid output from the resin column after adsorption.

5. The continuous polyphenol adsorption and resin regeneration system for walnut kernel decoction according to claim 3, characterized in that: The water boiling liquid buffer tank, demulsification and oil removal device, isoelectric point precipitation device, resin column, security filter, pipeline and valve are all made of non-metallic materials, which are one or more of unplasticized polyvinyl chloride, polypropylene, polyethylene, polytetrafluoroethylene or fiberglass.

6. The continuous polyphenol adsorption and resin regeneration system for walnut kernel decoction according to claim 3, characterized in that: The system is integrated onto a wheeled frame that is easy to move.

7. The continuous polyphenol adsorption and resin regeneration process for walnut kernel decoction according to claim 3, characterized in that: The rinsing fluid generated from rinsing the resin column can also be returned to the boiling liquid buffer tank for further treatment, so as to achieve ethanol recovery and scattered discharge of boiling liquid.

8. The continuous polyphenol adsorption and resin regeneration system for walnut kernel decoction according to claim 3, characterized in that: The resin column contains a multi-layered adsorption structure consisting of a molecular gel layer, a core enrichment layer, and a refined capture layer connected sequentially from top to bottom. The molecular gel layer intercepts large molecular impurities in the boiled walnut kernel extract, the core enrichment layer adsorbs walnut polyphenols from the boiled walnut kernel extract, and the refined capture layer captures highly polar, water-soluble small molecules that penetrate the core enrichment layer. The outlet of the resin column is connected to two enrichment liquid recovery tanks and a waste liquid tank via pipes and valves. Multiple ethanol storage tanks are provided for storing ethanol of different purities.

9. A continuous process for polyphenol adsorption and resin regeneration of walnut kernel decoction, characterized in that, The treatment using the continuous walnut kernel decoction polyphenol adsorption and resin regeneration system as described in claims 1-8 includes the following steps: Step S1: The walnut kernel decoction produced from the processing of walnut kernels is sent to the front-end pretreatment unit for buffering and filtration, and a clear walnut kernel decoction is output. Step S2: Then, the clarified walnut kernel decoction is sent to the middle adsorption unit to adsorb walnut polyphenols through the adsorption line and then discharged or sent to the tail regeneration unit. Step S3: The concentration of polyphenols in the liquid output from the resin column after adsorption is monitored in real time by an online polyphenol concentration detector on the output pipe of each resin column on the adsorption line, and it is determined whether the resin column has been saturated with adsorption. Step S4: The ethanol desorption agent in the ethanol storage tank of the tail end regeneration unit is pumped into the saturated resin column for desorption through the regeneration pump, and the resulting desorption liquid rich in high-purity walnut polyphenols is guided into the enrichment liquid recovery tank. Step S5: Use the regeneration pump to pump pure water from the pure water tank to the resin column after analysis to rinse away residual ethanol, and guide the rinse solution into the column wash return water tank. Step S6: Set the resin column that has been analyzed and cleaned to a standby state for subsequent use.

10. The continuous polyphenol adsorption and resin regeneration process for walnut kernel decoction according to claim 9, characterized in that, When the adsorption resin material has a multilayer adsorption structure, the following steps are also included: Step S401: 5%-15% ethanol is pumped from one of the ethanol storage tanks into the purified capture layer in the saturated resin column by the regeneration pump, and the resulting eluent rich in flavor substances is directed to one of the enrichment recovery tanks. In step S402, 60%-75% ethanol is pumped from another ethanol storage tank into the core enrichment layer inside the resin column for analysis. The resulting eluent, rich in high-purity walnut polyphenols, is then directed to another enrichment recovery tank. In step S403, 75%-95% ethanol is pumped from another ethanol storage tank into the molecular gel layer inside the resin column to remove physically trapped macromolecular impurities and output the regenerated waste liquid to the waste liquid tank.

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