A method for preparing a foam composite self-floating sponge and its photothermal interfacial evaporation application

Abstract

The application discloses a preparation method of a foam composite self-floating sponge and application of the foam composite self-floating sponge in a photo-thermal interface evaporation system. In the foaming process of preparing the porous sponge, a step of adding hydrophobic foam particles in situ is introduced, so that the composite material with the characteristics of quick water absorption, water conduction and self-floating is prepared by one-step method. The composite material can simultaneously meet the dual functions of water absorption, water conduction and self-floating. When the composite material is used as the base material of the photo-thermal interface evaporation system, the self-sustained and stable outdoor evaporation process can be ensured. Under the condition of simulated 1 solar radiation (1000 W / m 2 ), the technology realizes a water evaporation rate of up to 1.86 kg·m ‑2 ·h ‑1 ; and under the condition of natural sunlight (about 435 W / m 2 ), the average sewage evaporation rate reaches 1.70 kg·m ‑2 ·h ‑1 , and the daily average sewage evaporation amount is between 12.0 and 14.0 kg·m ‑2 .

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solar photothermal interfacial evaporation, and particularly relates to a preparation method of a foam composite self-floating sponge and photothermal interfacial evaporation application thereof. BACKGROUND

[0002] Solar photothermal evaporation is a natural process that occurs all the time in nature and is one of the important links of hydrological cycle in nature. The energy source is the sun, and the application direction is seawater desalination, sterilization and disinfection, freshwater acquisition, sewage treatment and the like. As a natural process, solar photothermal interfacial evaporation has unique advantages in sewage treatment: without specific sewage type and concentration limitation, high effluent quality, no equipment investment and maintenance, zero energy consumption, and small land occupation and flexible and movable device. However, although the advantages are obvious, there are few reports on the actual application of this technology, which is mainly limited by the fact that the sewage treatment rate is much lower than that of conventional industrial methods, and the existing solar photothermal interfacial evaporator cannot realize simple and low-cost preparation of large-size samples and spontaneous and long-time continuous and stable evaporation. SUMMARY

[0003] Therefore, the foam composite self-floating sponge material is designed and prepared in the application, and is specially applied to the base layer of the photothermal interfacial evaporator. The material successfully realizes continuous and stable outdoor solar evaporation of sewage treatment without external intervention, and exhibits high efficiency and stability in actual application.

[0004] In the foaming process of preparing the porous sponge, the step of adding hydrophobic foam particles in situ is introduced, so that the composite material with the characteristics of rapid water absorption and water conduction and self-floating is prepared by one-step method. By adjusting the addition proportion of the foam particles, the floating height of the composite material on the liquid surface can be conveniently adjusted. By taking the composite material as the base of the photothermal interfacial evaporator, and combining the photothermal interfacial evaporation layer, a large-size, simple and low-cost photothermal interfacial evaporator can be manufactured, which can spontaneously and continuously and stably evaporate for a long time, and fully utilize solar energy for sewage treatment.

[0005] The preparation method of the foam composite self-floating sponge includes the following steps:

[0006] Step 1: The sponge foaming raw material liquid and the foaming solidification liquid (Haisi 901 high resilience material combination, purchased from Beijing Haisi Company) are mixed at a certain proportion, placed in a flat-bottomed container, and uniformly stirred by a fast mechanical stirrer, and the stirring time is controlled to be less than 1 minute;

[0007] Step 2: Mix a certain proportion of foam particles into it, and uniformly stir quickly by machine within 2 minutes; complete foaming and drying after standing for 5-10 minutes, and cut the sponge foam composite material into a sheet with a thickness of 1-10 cm;

[0008] Step 3: Mix the light-heat conversion substance and the hydrogel matrix material to obtain a pre-gelatinized composite liquid;

[0009] Step 4: Dip one side of the sheet-shaped sponge foam composite material prepared in Step 2 into the pre-gelatinized composite liquid in Step 3, and obtain a self-floating foam / sponge / hydrogel composite material after the hydrogel is solidified.

[0010] In Step 1, the sponge comprises one or more of melamine, polyurethane, polyester, polyether, and polyvinyl alcohol, and is preferably melamine or polyurethane.

[0011] In Step 2, the foam comprises one or more of polystyrene, polyurethane, polyethylene, polypropylene, plastic foam, and rubber foam, and is preferably spherical and granular, solid or hollow, and has a particle (equivalent) diameter of 2-10 mm.

[0012] In Step 2, the ratio of the volume of the foam to the volume of the sponge is 1-4:8. The foam is a low-density and large-liquid-displacement-volume material, and the height of the overall evaporator above the liquid surface can be adjusted by adjusting the ratio of the foam to the sponge, which is closely related to the appropriate water supply capacity.

[0013] In Step 2, the porosity of the foam after foaming is controlled to be 70%-99%, and is preferably 80%-90%; and the pore size distribution is controlled to be 20 μm-2 mm, and is preferably 200-600 μm. The sponge foam composite material after foaming is cut into a sheet with a thickness of 1-10 cm, and is preferably 3-7 cm. The thickness is the thickness of the main material, i.e. the thickness of the solar light-heat interface evaporator.

[0014] In Step 3, the light-heat conversion substance is activated carbon powder. The hydrogel matrix material comprises one or more of polyvinyl alcohol hydrogel, polyacrylamide hydrogel, polyacrylic acid hydrogel, and polysaccharide hydrogel, and the mass fraction of the activated carbon powder in the hydrogel pre-polymer solution is 1 wt%.

[0015] In the present application, the hydrogel composite material is arranged on one side of the sponge foam composite material to form a light-heat evaporation layer with a thickness of 0.2-10 mm, and is preferably 1-3 mm. The loading amount of the light-heat conversion substance composite hydrogel matrix on the surface of the sponge sheet is 0.2-4 g / cm 2 , and is preferably 1.0-3.0 g / cm 2 .

[0016] The application of the foam composite self-floating sponge material in photothermal interface evaporation.

[0017] The sponge foam composite material prepared by the application is used for realizing the self-floating and continuous water supply functions of the photothermal interface evaporator, and can be applied to solar evaporation sewage treatment.

[0018] The raw materials sponge, foam, photothermal conversion material and synthetic hydrogel raw material selected by the application are low in price, and no equipment expenditure is needed, so that the cost is effectively controlled.

[0019] The size of the sponge foam composite material prepared by the application depends on the selection of the foaming container, so that the simplicity of preparing the self-floating base layer in a large size is ensured.

[0020] The synthetic method of the hydrogel selected by the application is simple, can quickly gel at room temperature, and the gelation process can be carried out in situ in the sponge gap, so that the thickness of the photothermal interface evaporation layer can be conveniently controlled, and the simple and low-cost preparation of the large-size evaporator is ensured.

[0021] The sponge material selected by the application provides excellent water supply ability from bottom to top, which ensures the continuous stability of the evaporation process of the evaporator.

[0022] The foam material selected by the application endows the sponge material and the whole evaporator with self-floating property, so that the evaporator can follow the fluctuation of the liquid surface and maintain stable water supply ability, which ensures the spontaneous, long-time continuous stability of the evaporation process of the evaporator.

[0023] The application combines the high light absorption (light absorption rate of about 86%) and thermal conversion of the photothermal conversion substance, the thermal localization of the photothermal evaporation layer, the 3D support and excellent water supply ability from bottom to top of the sponge material, the high thermal insulation ability and self-floating performance of the foam, and the room-temperature in-situ gelation hydrogel system to realize the simple and low-cost preparation of the large-size evaporator and the spontaneous, long-time continuous evaporation performance. The preparation cost of the solar photothermal interface evaporator is about 65 yuan / m 2 ; when treating actual sewage, the continuous operation is carried out for 10 days (the maximum solar intensity is about 435 W / m 2 ), the average daily water evaporation rate in the daytime is 1.70 kg·m -2 ·h -1 , which is significantly higher than the rate 1.10 kg·m -2 ·h -1 of direct evaporation of sewage under the same condition, the daily water evaporation rate in the daytime keeps stable within 10 days, and the daily sewage treatment amount within 10 days is 12.0 ~ 14.0 kg·m -2 .

[0024] The solar light-heat evaporator is a low-cost and high-efficiency solar interface evaporation system, has the advantages of functional partition, simple process, almost no operation, easy large-scale preparation, high energy utilization rate, high spontaneous operation degree, small land occupation, high flexibility, low maintenance cost, and can be used for sewage treatment, especially sewage treatment, and has good economic benefit, environmental benefit and commercialization prospect. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Surface of PU sponge / PS foam composite material in Example 1 of the present application.

[0026] Figure 2 Surface of PU sponge / PS foam / SA hydrogel composite material in Example 2 of the present application.

[0027] Figure 3 Evaporation curve of PU sponge / PS foam / SA hydrogel composite material in Example 2 of the present application under simulated 1 sun.

[0028] Figure 4 Evaporation curve of PU sponge / PS foam / SA hydrogel composite material in Example 2 of the present application under actual sunlight on September 8, 2024 (sample 1, 2 and 3 are three parallel sample tests).

[0029] Figure 5 Daily average maximum moisture evaporation rate of PU sponge / PS foam / SA hydrogel composite material in Example 3 of the present application under actual sunlight from September 2 to 12, 2024 (sample 1, 2 and 3 are three parallel sample tests).

[0030] Figure 6 Daily average sewage evaporation amount of PU sponge / PS foam / SA hydrogel composite material in Example 4 of the present application under actual sunlight from September 2 to 12, 2024 (sample 1, 2 and 3 are three parallel sample tests). DETAILED DESCRIPTION

[0031] The present application provides a self-floating solar light-heat interface evaporator, comprising a light-heat interface evaporation layer and a self-floating base layer; the light-heat interface evaporation layer comprises a hydrogel material and a light-heat conversion substance dispersed therein, and a pre-gelatinized solution mixed with the light-heat conversion substance is prepared by in-situ gelatinization in the voids on one side of the sponge; the self-floating base layer comprises a sponge and a foam.

[0032] Unless otherwise specified, the raw materials of the present application have no special requirements and can be directly used as common commercially available goods well known to those skilled in the art.

[0033] The self-floating solar photothermal interface evaporator provided by the application comprises a sponge. The sponge is porous, and the material is preferably melamine, polyurethane, polyester, polyether or polyvinyl alcohol, and more preferably melamine or polyurethane; the porosity of the sponge is preferably 70% to 99%, and more preferably 80% to 90%, and the internal pore size distribution is preferably 20 μm to 2 mm, and more preferably 200 to 600 μm. The flat sponge is cut into a desired size, and the thickness is preferably 1 to 10 cm, and more preferably 3 to 7 cm. The area is preferably 0.5 m x 0.5 m and 1.0 m x 1.0 m, or other sizes are cut according to the actual wastewater treatment scale.

[0034] The self-floating solar photothermal interface evaporator provided by the application comprises a foam. The shape of the foam is preferably spherical granular; the material of the foam is preferably polystyrene, polyurethane, polyethylene, polypropylene, plastic, rubber, and more preferably polystyrene; and the composite method of the foam and the sponge is to dope the foam particles in situ during the synthesis of the sponge.

[0035] The self-floating solar photothermal interface evaporator provided by the application comprises a photothermal conversion substance. The photothermal conversion substance is preferably one or more of metal particles, carbon materials, organic small molecules, polymers and biomass materials, and more preferably activated carbon powder in the carbon materials.

[0036] The self-floating solar photothermal interface evaporator provided by the application comprises a hydrogel matrix, which is preferably one or more of polyvinyl alcohol hydrogel, polyacrylamide hydrogel, polyacrylic acid hydrogel and polysaccharide hydrogel, and more preferably polyvinyl alcohol hydrogel or sodium alginate / calcium ion hydrogel; and the water content of the hydrogel is preferably 50% to 98%, and more preferably 80% to 95%.

[0037] The self-floating solar photothermal interface evaporator provided by the application comprises a photothermal interface evaporation layer, and the thickness is preferably 0.2 to 10 mm, and more preferably 1 to 3 mm. The loading amount of the hydrogel matrix compounded with the photothermal conversion substance on the surface of the sponge sheet is preferably 0.2 to 4 g·cm -2 , and more preferably 1.0 to 3.0 g·cm -2 .

[0038] The self-floating solar photothermal interface evaporator provided by the application combines the high light absorption (light absorption rate of about 86%), heat conversion, heat localization of the photothermal evaporation layer, 3D support and excellent water supply capacity from bottom to top of the sponge material, high heat insulation capacity and self-floating performance of the foam, and the functional partition design of anisotropy not only guarantees the functional requirements but also saves the amount of material used, and the room temperature in-situ gelation hydrogel system realizes the simple and low-cost preparation of a large-size evaporator and the spontaneous and long-time continuous and stable evaporation performance.

[0039] The application further provides a preparation method of the floating solar evaporator.

[0040] In-situ doping of the foam particles in the process of synthesizing the sponge;

[0041] Mixing the light-heat conversion material and various raw materials for synthesizing the hydrogel according to a certain proportion to obtain a pre-gelation composite liquid, immediately immersing the prepared sponge / foam composite material in the pre-gelation composite liquid, and solidifying to obtain the self-floating sponge / foam / hydrogel solar light-heat interface evaporator.

[0042] The application combines the high light absorption (light absorption rate of about 86%) and heat conversion of the light-heat conversion material, the heat localization of the light-heat evaporation layer, the 3D support and excellent water supply capacity from bottom to top of the sponge material, the high heat insulation capacity and self-floating performance of the foam, and the room temperature in-situ gelation hydrogel system to realize the simple and low-cost preparation of the large-size evaporator and the spontaneous, long-time continuous and stable evaporation performance. 2 ; when treating the actual wastewater, the solar light-heat interface evaporator is continuously operated for 10 days (the maximum solar light intensity is about 435 W / m 2 ), the average daily water evaporation rate is 1.70 kg·m -2 ·h -1 , which is much higher than the rate 1.10 kg·m -2 ·h -1 of direct evaporation of the wastewater under the same condition, the daily water evaporation rate is stable within 10 days, and the daily wastewater treatment capacity is 12.0 ~ 14.0 kg·m -2 .

[0043] The solar light-heat evaporator is a low-cost and high-efficiency solar interface evaporation system, has the advantages of functional partition, simple process, almost no operation, easy large-scale preparation, high energy utilization rate, high spontaneous operation degree, small occupation area, high flexibility, low maintenance cost, and can be used for wastewater treatment, especially wastewater treatment, and has good economic benefit, environmental benefit and popularization prospect in civil and commercial use.

[0044] The application further provides the application of the floating solar evaporator or the self-floating solar light-heat interface evaporator prepared by the preparation method in wastewater treatment and / or wastewater treatment.

[0045] The application mode of the self-floating solar light-heat interface evaporator in wastewater treatment and / or wastewater treatment is not specially limited, and the application mode well known in the art can be used.

[0046] The technical solutions in the present application will be described clearly and completely below in combination with the embodiments in the present application, but they should not be understood as limitations to the protection scope of the present application.

[0047] Example 1:

[0048] 10 g of polyurethane foaming solution was weighed, 0.8 g of PS foam particles (diameter 3-5 mm) was added thereto, 4 g of sponge foaming curing agent was added after uniform mixing, and the foaming was completed after about 2 minutes, to obtain a PU sponge / PS foam composite material, which was cut into a sheet with a thickness of 3 cm and used as a self-floating base layer of a solar photo-thermal interface evaporator (see Figure 1 ). In the subsequent test, this sample was used as a reference sample for photo-thermal evaporation test (i.e. Figure 4 、 5 , the PU sponge sample in Example 6).

[0049] Example 2:

[0050] The PU sponge / PS foam composite material was prepared in the same manner as in Example 1.

[0051] 10.0 g of 2 wt% sodium alginate (SA) aqueous solution was weighed, 0.10 g of activated carbon powder was added, and the activated carbon powder was uniformly dispersed by mechanical stirring. The prepolymer solution was absorbed on one side of the PU sponge / PS foam by the dipping method at a rate of 2.0 g·cm -2 , and then it was immersed in a 2 wt% CaCl2 aqueous solution, and the gelation was completed after 30 min, to obtain a self-floating PU sponge / PS foam / SA hydrogel solar photo-thermal interface evaporator (see Figure 2 ).

[0052] Treatment example:

[0053] Actual sewage treatment in natural environment: the solar photo-thermal interface evaporator in Example 2 was used, the actual sewage sample was sewage from a small pond in the campus of Anhui University, the sewage was placed in an open circular container with a height of 0.16 m and a radius of 5 cm, the sewage height was 0.15 m, and the solar photo-thermal interface evaporator in Example 1 was overlaid, and the solar photo-thermal evaporation experiment was carried out in a place with good ventilation and sunny weather. Another reference experiment group was set up, and the only difference was that no article was covered, and the sewage was directly naturally evaporated under the same conditions. The experiment started at 8:00 and ended at 17:00, and the mass of the entire experimental system was weighed at the beginning of the experiment and every hour, and the water evaporation rate (kg·m -2 ·h -1), while recording the actual solar radiation intensity and wind speed data. Continue the experiment for 24 hours, and calculate the average daily evaporation rate (kg·m -2 ). The test was conducted continuously for 10 days from September 2 to 12, 2024 (September 11 was cloudy and rainy, so no data was collected). Three parallel samples were tested at the same time (sample 1, 2, and 3). The evaporation curve for September 8, 2024 is given as follows: Figure 4 The average daily maximum water evaporation rate data under actual sunlight from September 2 to 12, 2024 is as follows Figure 5 The average daily sewage evaporation data under actual sunlight from September 2 to 12, 2024 is as follows: Figure 6 shown.

[0054] Performance test data:

[0055] In Example 2, the sample was evaporated under simulated 1 sun, and the evaporation rate was 1.86 kg·m -2 ·h -1 (See Figure 3 ).

[0056] In the actual sewage natural environment (the highest sunlight intensity is about 435 W / m 2 The average maximum photothermal evaporation rate of the photothermal interface evaporator in the 10-day treatment of Example 1 was 1.81 kg·m -2 ·h -1 (See Figure 5 ), with an average daily sewage treatment capacity of 13.1 kg·m -2 (See Figure 6 ).

[0057] In the actual sewage natural environment (the highest sunlight intensity is about 435 W / m 2 The average maximum photothermal evaporation rate of the photothermal interface evaporator in the 10-day treatment of Example 2 was 1.62 kg·m -2 ·h -1 (See Figure 5 ), with an average daily sewage treatment capacity of 12.5 kg·m -2 (See Figure 6 ).

[0058] In the actual sewage natural environment (the highest sunlight intensity is about 435 W / m 2 The average maximum photothermal evaporation rate of the photothermal interface evaporator in the 10-day treatment of Example 3 was 1.67 kg·m -2 ·h -1 (See Figure 5 ), with an average daily sewage treatment capacity of 12.5 kg·m -2(see Figure 6 Since the experiment was carried out in early September 2024, the actual daytime maximum solar intensity was only 0.435 times that of 1 sun (1000 W / m 2 The actual sewage treatment rate in the normal summer outdoor environment is expected to be higher.

[0059] It can be seen that the self-floating sponge / foam / hydrogel solar photothermal interface evaporator has excellent spontaneous continuous stability, significantly improves the sewage treatment rate compared with the reference group, relies only on solar energy, has low cost and good flexibility, and has good economic and environmental benefits in popularization and application.

[0060] Although the above embodiment describes the present application in detail, it is only a part of the embodiments of the present application but not all the embodiments, and other embodiments can be obtained according to the present embodiment without creativity, which all belong to the protection scope of the present application.

[0061] The above is only a preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a self-floating foam / sponge / hydrogel composite material, characterized in that The steps include: Step 1: Mix the sponge foaming raw material liquid and the foaming curing liquid, place them in a flat-bottomed container, and quickly stir them mechanically until evenly mixed. The stirring time should be controlled within 1 minute. Step 2: Add the foam particles to the system of step 1 and stir them mechanically for 2 minutes or less. After standing for 5 to 10 minutes, the foaming and drying are completed. The sponge foam composite material is cut into sheets with a thickness of 1 to 10 cm. Step 3: mixing the photothermal conversion material and the hydrogel matrix material to obtain a pre-gelled composite liquid; Step 4: dipping one side of the sheet-like sponge foam composite material prepared in step 2 into the pre-gelled composite liquid prepared in step 3, and obtaining a self-floating foam / sponge / hydrogel composite material after the hydrogel is solidified; The sponge comprises one or more of melamine and polyurethane; after foaming, the porosity of the sponge is controlled at 70% to 99%, the pore size distribution is controlled at 20 μm to 2 mm, and the thickness is 1 to 10 cm; The foam includes one or more of polystyrene, polyurethane, polyethylene, polypropylene, and rubber foam materials; The ratio of the foam volume to the sponge volume is 1-4:8; The photothermal conversion substance is activated carbon powder; the hydrogel matrix material includes one or more of polyvinyl alcohol hydrogel, polyacrylamide hydrogel, polyacrylic acid hydrogel, and polysaccharide hydrogel; The photothermal conversion substance accounts for 1 wt% of the mass of the pre-gelled composite liquid; the loading amount of the pre-gelled composite liquid on the surface of the sponge sheet is 0.2-4 g / cm 2 .

2. The preparation method according to claim 1, wherein: The foam is in the form of solid or hollow spherical particles with a diameter of 2 to 10 mm.

3. The preparation method according to claim 1, wherein: The hydrogel composite material is arranged on one side of the sponge foam composite material to form a photothermal evaporation layer with a thickness of 0.2 to 10 mm.

4. Use of the self-floating foam / sponge / hydrogel composite material prepared by the preparation method according to any one of claims 1 to 3 in photothermal interface evaporation.

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