A treatment device and method for improving the water transport performance of PVA-based hydrogel photothermal evaporation materials

Abstract

The present invention relates to a treatment device for improving the water conveyance performance of a PVC-based hydrogel photothermal evaporation material, including a piercing treatment device, a surface repeated thermal deformation treatment device, a surface grinding and sweeping treatment device, and a surface hydrophilic modification treatment device; the piercing treatment device includes a piercing tool, perforations, a hydrogel, and a low-density high-strength material plate. The hydrogel is placed on the low-density high-strength material plate, and the hydrogel is pierced by the piercing tool to form uniformly distributed perforations; the surface repeated thermal deformation treatment device includes an aging lamp and deionized water, and the hydrogel after piercing treatment is placed directly below the aging lamp. The beneficial effects of the present invention are as follows: through the piercing treatment device and a series of horizontal water conveyance modification combined treatment devices, the present invention improves the vertical and horizontal water conveyance capabilities of the gel material, can greatly improve the water evaporation rate under the same conditions, significantly improves the photothermal utilization efficiency, and the treatment process is environmentally friendly, pollution-free, simple and easy to operate, and has low cost.

Description

Technical Field

[0001] The present invention relates to the fields of hydrogel, photothermal evaporation, material modification and surface treatment, and in particular to a treatment device and method for improving the water conductivity of a PVA-type hydrogel photothermal evaporation material. Background Art

[0002] At present, seawater desalination technology is constantly receiving widespread attention and application. Affected by the natural evaporation rate, photothermal seawater desalination technology has not been fully developed. As a kind of interfacial evaporation material, hydrogel has attracted the attention and research of many research teams at home and abroad for its ability to greatly increase the evaporation rate of seawater. PVA hydrogel is a hydrophilic polymer synthesized with polyvinyl alcohol (PVA) as the main monomer and aldehydes. The polymer material has a cross-linked spatial network structure. Coupling photothermal materials with hydrogels can obtain gel photothermal evaporation materials (hereinafter referred to as gel materials). The properties of hydrogels absorbing and storing water and photothermal materials absorbing and converting solar energy can realize the interfacial evaporation of water. However, although hydrogels have strong water absorption and water storage capabilities, their water transport capacity is still the controlling step that limits the water evaporation rate.

[0003] In order to improve the water transport capacity of gel materials, cyclic freezing-thawing treatment and vacuum freeze-drying treatment are usually used. The cyclic freezing-warming process is essentially the freezing and melting process of water in the gel material. When the water in the gel freezes, the volume expands, the skeleton is enlarged, and the porosity increases. When the ice melts, the volume shrinks, the skeleton recovers, and the porosity decreases. During the cyclic freezing-warming process, some covalent bonds between polymer molecules break under the action of alternating stress, resulting in micropores, which is beneficial to the gel material to improve its water absorption capacity. Related literature: "Preparation and Swelling Properties of Polyvinyl Alcohol / Gelatin Blend Gel Film" published by Sun Wei, Feng Guangfeng, and Qiao Congde in Journal of Qilu University of Technology, 2019, 1-4. Cyclic freezing treatment can improve the water transport capacity of gel materials to a certain extent, but the improvement capacity is limited. Vacuum freeze-drying treatment is to freeze the prepared gel material and then vacuum dry it. The frozen ice inside the material directly sublimates to produce pores, so that a microporous structure is produced in the material, thereby improving the water transport capacity. After treatment by this method, the porosity is increased and the water transmission capacity is improved, but the gel material often undergoes irreversible deformation during the treatment process, so this treatment method has certain side effects.

[0004] At present, there is no report on an effective method for modifying the water transport capacity of gel materials. Therefore, it is extremely important and urgent to propose a processing device and method for improving the water transport performance of PVA hydrogel photothermal materials. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a processing device and method for improving the water transport performance of PVA-based hydrogel photothermal evaporation materials.

[0006] The treatment device for improving the water transport performance of PVA hydrogel photothermal evaporation materials includes a piercing treatment device, a surface repeated thermal deformation treatment device, a surface grinding and sweeping treatment device and a surface hydrophilic modification treatment device; the piercing treatment device includes a piercing tool, perforations, hydrogel and a low-density high-strength material plate, the hydrogel is placed on the low-density high-strength material plate, and the hydrogel is pierced by the piercing tool to form evenly distributed perforations; the surface repeated thermal deformation treatment device includes an aging lamp and deionized water, the hydrogel after piercing treatment is placed directly under the aging lamp, and the hydrogel after baking and deformation is immersed in deionized water; the surface grinding and sweeping treatment device includes a grinding and sweeping tool, a motion machine and an anti-skid pad, the hydrogel is placed on the anti-skid pad, the grinding and sweeping tool is located above the hydrogel, the grinding and sweeping tool is installed on the motion machine, the motion machine actuator consists of transverse and longitudinal guide rails and a mechanical arm installed thereon and moving along the guide rails, and the mechanical arm is connected to the grinding and sweeping tool; the surface hydrophilic modification treatment device includes a hydrophilic solution, and the hydrogel is immersed in the hydrophilic solution.

[0007] Preferably, the piercing tool should have different calibers and a hard texture, including various types of needles, syringe needles, drill bits, capillaries, sticks or nails, etc. The outer diameter of the piercing tool should be in the range of 0.5-2mm, the perforation interval should be in the range of 3-20mm, and the perforation should be perpendicular to the hydrogel surface to ensure the shortest perforation path.

[0008] Preferably, the grinding and sweeping tool should have a certain rigidity and a certain roughness, including various types of brushes, sandpaper or steel wool and the like.

[0009] The processing method of the processing device for improving the water transport performance of PVA-type hydrogel photothermal evaporation materials comprises the following steps:

[0010] Step 1), placing the PVA hydrogel after a certain period of time after preparation on a low-density and high-strength material plate to ensure that the lower part of the hydrogel has good support;

[0011] Step 2), use a piercing tool to vertically pierce the hydrogel at a certain interval, and the perforations need to extend to the inside of the low-density and high-strength material plate to ensure that the hydrogel is perforated through;

[0012] Step 3), repeated thermal deformation treatment of the surface: the hydrogel that has been pierced is placed under an aging lamp for baking. When the hydrogel loses water and deforms into a concave shape, the baking is terminated and the hydrogel is immersed in deionized water until the shape is restored. After repeating this process 3-5 times, a gel material with improved water conductivity is obtained.

[0013] Step 4), surface grinding and sweeping treatment: prepare a grinding and sweeping tool, use it manually or install it on a moving machine; place the hydrogel that has been pierced on a material with a large friction coefficient, grind and sweep the hydrogel manually or use a moving machine equipped with a grinding and sweeping tool until the surface of the gel material forms a suitable roughness;

[0014] Step 5), surface hydrophilic modification treatment: prepare a hydrophilic solution of a certain concentration; soak the pierced gel material in the hydrophilic solution for a certain period of time or apply a surface coating to the gel material, and place it for a certain period of time after the treatment is completed, and finally obtain a gel material with improved vertical and horizontal water conduction performance.

[0015] As a preference: the hydrogel prepared in step 1) should be processed within no more than 12 hours; the low-density high-strength material board can be a medium-density foam board, including a density of 20-50kg / m 3 EPS foam board, XPS foam board or PU board within the range can be used to ensure that the material is well supported and easy to puncture during the puncture process, and will not deform within the baking temperature range of 80-300℃.

[0016] Preferably, the piercing process in step 2) should be completed quickly to avoid cracking of the gel due to puncture, thereby affecting the strength of the gel structure.

[0017] Preferably, in step 3), the power of the aging lamp should be 100W or above to ensure the baking speed. The distance between the aging lamp and the hydrogel should be between 100-300mm, so that the deformation speed is appropriate but water vapor does not gather on the surface of the aging lamp. During the baking process, the angle of the hydrogel should be rotated in the horizontal direction at regular intervals to ensure uniform heating and no uneven deformation. The baking is stopped when the upper surface of the hydrogel is obviously dry and uniformly concave, and the hydrogel is transferred to deionized water and soaked until the shape of the hydrogel is restored. Repeating the baking-immersion process requires ensuring that the hydrogel fully loses water, deforms, and absorbs water to recover.

[0018] Preferably, in step 4), the material with a large friction coefficient should ensure that the gel does not move during the grinding and sweeping process, including various types of filter paper, sandpaper, anti-slip plates, anti-slip films or anti-slip pads.

[0019] Preferably: in step 4), the motion machine should be pressure-adjustable and controllable, and the motion machine actuator is composed of transverse and longitudinal guide rails and a mechanical arm mounted thereon and movable along the guide rails, and the mechanical arm drives the grinding and sweeping tools to perform the same motion, and the motion modes include horizontal reciprocating, circular rotation, centrifugal rotation, centripetal rotation or specific path operation.

[0020] Preferably, in step 5), the hydrophilic solution should have good hydrophilic properties, including various hydrophilic surfactants.

[0021] As a preference: after the treatment in step 5), the hydrophilic solution should be allowed to stand for a certain period of time to ensure that it is exchanged below the surface of the gel and does not fall off.

[0022] The beneficial effects of the present invention are as follows: the present invention improves the vertical and horizontal water transport capacity of the gel material through the piercing treatment device and a series of horizontal water transport modification combined treatment devices, which can greatly increase the water evaporation rate under the same conditions, significantly improve the light and heat utilization efficiency, and the treatment process is environmentally friendly and pollution-free, simple and easy to operate, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of gel piercing treatment (Figure a is a front view of gel piercing treatment, and Figure b is a top view of gel piercing treatment);

[0024] Figure 2 Schematic diagram of repeated thermal deformation treatment of gel surface (Figure a is a schematic diagram of baking deformation, and Figure b is a schematic diagram of immersion recovery);

[0025] Figure 3 Schematic diagram of the grinding and sweeping treatment of the gel surface (Figure a is a schematic diagram of mechanical grinding and sweeping, and Figure b is a schematic diagram of manual grinding and sweeping);

[0026] Figure 4 Schematic diagram of hydrophilic modification treatment of gel surface (Figure a is a schematic diagram of immersion treatment, and Figure b is a schematic diagram of brushing treatment);

[0027] Figure 5 It is a schematic diagram of the combined treatment device for gel water transfer and modification;

[0028] Figure 6 Schematic diagram of the water transport process during gel evaporation.

[0029] Explanation of the reference numerals: piercing tool 1, perforation 2, hydrogel 3, low-density high-strength material plate 4, aging lamp 5, grinding and sweeping tool 6, motion machine 7, anti-slip mat 8, hydrophilic solution 9, sample carrier 10, container 11, deionized water 12. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principles of the present invention, several improvements and modifications may be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0031] In view of the insufficient water transport capacity of existing gel materials, a treatment method for improving the water transport performance of PVA hydrogel photothermal materials is provided. The gel material is pierced to improve its vertical water transport capacity, and the gel material is successively subjected to surface repeated thermal deformation treatment, surface grinding treatment and surface hydrophilic modification treatment to improve its horizontal water transport capacity, thereby improving the overall water transport capacity of the gel material. The principles are: ① Vertical piercing can produce small-sized perforations in the vertical direction of the gel. Under the action of capillaries, water can be transported to the surface of the gel through the perforations, thereby improving its vertical water transport capacity; ② Surface repeated thermal deformation treatment is to repeatedly bake and soak the gel material. During the baking process, the surface of the gel material loses water and undergoes concave deformation. When the water loss reaches a certain level, the polymer skeleton structure of the surface layer develops. The gel absorbs water and becomes flat during the soaking process, but the change in the polymer skeleton structure of the surface layer makes it unable to recover its deformation, and the surface becomes rough, which enhances the capillary effect and increases its horizontal water transport capacity; ③ Surface grinding and sweeping treatment is to make the surface roughness of the gel material that has been repeatedly thermally deformed further increase and more uniform by grinding and sweeping, and enhance the capillary effect, thereby increasing its horizontal water transport capacity; ④ Surface hydrophilic modification treatment is to brush the surface hydrophilic solvent on the surface of the gel material after the above treatment, and completely change its surface properties by introducing hydrophilic groups, thereby greatly improving its horizontal water transport capacity. This series of treatment methods can greatly increase the interface evaporation rate of gel materials and is used in the fields of photothermal evaporation and solar desalination.

[0032] A polyvinyl alcohol (PVA)-glutaraldehyde (Glu)-polypyrrole (Ppy) hydrogel was placed on an XPS foam board after a period of preparation, and a 12-gauge needle was used to pierce the surface of the hydrogel at certain intervals (e.g. Figure 1 As shown), and then surface treatment: ① Surface repeated thermal deformation treatment (such as Figure 2 As shown): Place the pierced hydrogel 3 under an aging lamp 5 for baking. When the gel loses water and deforms into a concave shape, remove it and soak it in deionized water 12 until the shape is restored. Repeat the baking-immersion operation 3-5 times to complete the post-treatment; ② Surface grinding and sweeping treatment (such as Figure 3 3. Place the pierced hydrogel 3 on filter paper and use a handheld grinding and sweeping tool to grind the gel until the surface of the gel material forms a suitable roughness; 4. Surface hydrophilic modification (such as Figure 4 As shown in the figure): The gel material that has been pierced is soaked in a sodium dodecyl sulfate solution for a certain period of time and then placed for a certain period of time to obtain a gel material with improved water conductivity. Figure 5 shown.

[0033] The treatment time was 2 h after the gel preparation was completed.

[0034] The XPS foam board used is a medium-density foam board with a density of 30kg / m 3 .

[0035] A 12-gauge needle with an outer diameter of 1.2 mm was used, and the puncture interval was 10 mm. During puncture, the needle was perpendicular to the gel surface. The puncture process was completed quickly, and the gel was punctured without cracking.

[0036] The power of the aging lamp is 300W, the distance between the aging lamp and the gel is 200mm, the deformation speed is appropriate and the steam will not gather on the surface of the aging lamp. The gel angle is rotated regularly during the baking process, the gel is heated evenly, and the deformation is evenly uniform. The baking is stopped when the upper surface of the gel is obviously dry and uniformly concave, and the gel is transferred to deionized water and soaked until the gel shape is restored. Repeat the baking-immersion process 3 times to ensure that the gel is fully dehydrated, deformed, and recovered by water absorption.

[0037] The treated gel is placed on filter paper to prevent the gel from moving during the grinding and sweeping process, and the gel is reciprocated by using a handheld grinding and sweeping tool until the surface of the gel material forms a suitable roughness.

[0038] A sodium dodecyl sulfate solution with a concentration of 20 mg / L was prepared and poured into a container.

[0039] The gel material having undergone the above roughening treatment was immersed in a sodium dodecyl sulfate solution for a certain period of time and then left for 30 seconds to obtain a gel material with improved water-conducting performance.

[0040] The following is an example of a treatment method for improving the water transport performance of PVA hydrogel photothermal evaporation materials: the gel material treated by puncture + repeated surface thermal deformation, puncture + surface grinding and sweeping, and puncture + surface hydrophilic modification is fully swollen in seawater with a salt content of 3.5% until the volume is stable, and a mold is used to cut the gel material into a volume of 12.6 cm 2 The gel material is placed on a sample evaporation table composed of XPS and absorbent paper. Water can be absorbed from the lower surface of the gel to the upper surface through the puncture holes, and then expand to the entire surface of the gel material through surface capillary action (the schematic diagram of the water transport process during gel evaporation is shown in Figure 2). Figure 6 as shown).

Claims

1. A treatment method for improving the water transportation performance of PVA-based hydrogel photothermal evaporation materials, characterized in that, a treatment device for improving the water transportation performance of PVA-based hydrogel photothermal evaporation materials is adopted. The treatment device includes a piercing treatment device, a surface repeated thermal deformation treatment device, a surface grinding and sweeping treatment device, and a surface hydrophilic modification treatment device; the piercing treatment device includes a piercing tool (1), a perforation (2), a hydrogel (3), and a low-density high-strength material plate (4). The hydrogel (3) is placed on the low-density high-strength material plate (4), and the hydrogel (3) is pierced by the piercing tool (1) to form uniformly distributed perforations (2); the surface repeated thermal deformation treatment device includes an aging lamp (5) and deionized water (12). The hydrogel (3) after piercing treatment is placed directly below the aging lamp (5), and the baked and deformed hydrogel (3) is immersed in the deionized water (12); the surface grinding and sweeping treatment device includes a grinding and sweeping tool (6), a motion mechanism (7), and an anti-slip pad (8). The hydrogel (3) is placed on the anti-slip pad (8), the grinding and sweeping tool (6) is located above the hydrogel (3), the grinding and sweeping tool (6) is installed on the motion mechanism (7), and the execution mechanism of the motion mechanism consists of horizontal and vertical guide rails and a robotic arm installed thereon and moving along the guide rails. The robotic arm is connected to the grinding and sweeping tool (6); the surface hydrophilic modification treatment device includes a hydrophilic solution (9), and the hydrogel (3) is immersed in the hydrophilic solution (9); the treatment method includes the following steps: Step 1): Place the hydrogel (3) within a certain period of time after preparation on a low-density high-strength material plate (4) to provide good support for the lower part of the hydrogel (3); the prepared hydrogel (3) is processed within no more than 12 hours; the low-density high-strength material plate (4) is selected from medium-density foam boards, including EPS foam boards, XPS foam boards or PU boards with a density in the range of 20-50 kg / m 3 ; Step 2), use the piercing tool (1) to vertically pierce the hydrogel (3) at a certain interval, and the perforation (2) extends into the low-density high-strength material plate (4) to make the hydrogel perforation penetrate through; Step 3), surface repeated thermal deformation treatment: place the hydrogel (3) after piercing treatment under the aging lamp (5) for baking, and end the baking when the hydrogel (3) loses water and deforms into a concave shape, and immerse it in the deionized water (12) until the shape is restored; repeat 3-5 times to obtain a gel material with improved water conduction performance; Step 4), surface grinding and sweeping treatment: prepare the grinding and sweeping tool (6), and use it manually or install it on the motion mechanism (7); place the hydrogel (3) on a material with a relatively large coefficient of friction, and use a manual method or the motion mechanism (7) equipped with the grinding and sweeping tool (6) to grind and sweep the hydrogel (3) until a suitable roughness is formed on the surface of the gel material; the material with a relatively large coefficient of friction in Step 4) includes filter paper, sandpaper, anti-slip plate, anti-slip film, or anti-slip pad; Step 5), surface hydrophilic modification treatment: configure a hydrophilic solution (9) with a certain concentration; immerse the gel material in the hydrophilic solution (9) for a certain time or apply it to the surface of the gel material, and place it for a certain time after treatment to finally obtain a gel material with improved vertical and horizontal water conduction performance.

2. The treatment method for improving the water transportation performance of PVA-based hydrogel photothermal evaporation materials according to claim 1, characterized in that: In step 3), the power of the aging lamp (5) is 100 W or above, and the distance between the aging lamp (5) and the hydrogel (3) is between 100 - 300 mm. During the baking process, the angle of the hydrogel is rotated regularly in the horizontal direction to make it evenly heated. The baking stops when the upper surface of the hydrogel (3) is significantly dried and shows a uniform concave shape. Then, the hydrogel (3) is transferred to deionized water (12) and soaked until the shape of the hydrogel is restored. The baking-soaking process is repeated to fully dehydrate and deform the hydrogel and then absorb water and restore its shape.

3. The treatment method for improving the water transportation performance of PVA-based hydrogel photothermal evaporation materials according to claim 1, characterized in that: In step 4), the pressure of the motion machinery (7) is adjustable and controllable. The execution mechanism of the motion machinery consists of horizontal and vertical guide rails and a robotic arm installed on them and moving along the guide rails. The robotic arm drives the grinding and sweeping tool (6) to perform the same motion, and the motion modes include reciprocating, circular rotating, centrifugal rotating, or centripetal rotating in the horizontal direction.

4. The treatment method for improving the water transportation performance of PVA-based hydrogel photothermal evaporation materials according to claim 1, characterized in that: In step 5), the hydrophilic solution (9) includes a hydrophilic surfactant.

5. The treatment method for improving the water transportation performance of PVA-based hydrogel photothermal evaporation materials according to claim 1, characterized in that: After the treatment in step 5), it is left for a certain period of time to allow the hydrophilic solution (9) to exchange below the gel surface.

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