Composite foam hydrogel organic sewage purifier and preparation method thereof

Abstract

The present invention relates to a composite foam hydrogel organic sewage purifier and a preparation method thereof. The technical solution is as follows: urea and carbon black are added to deionized water, stirred, dried, heated under a nitrogen atmosphere, washed, and filtered to obtain a carbon black composite g-C3N4 photocatalytic agent. Polyvinyl alcohol is added to deionized water, and then agar powder and carbon black composite g-C3N4 are added and stirred; then sodium dodecyl sulfate, dodecanol, and gum arabic are added and stirred continuously to obtain a composite foam hydrogel slurry, which is cast and freeze-dried to obtain a composite foam hydrogel. Carnauba wax and beeswax are added to anhydrous ethanol, stirred, and ultrasonically treated to obtain a hydrophobic mixed wax suspension. The hydrophobic mixed wax suspension is sprayed on a large plane on the surface of the composite foam, and freeze-dried to obtain a composite foam hydrogel organic sewage purifier. The process of the present invention is simple and low in cost; the product thus prepared not only has a long service life, but also has high water evaporation efficiency and organic matter degradation efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of photothermal conversion technology and specifically relates to a composite foam hydrogel organic sewage purifier and a preparation method thereof. Background Art

[0002] In the field of photothermal conversion technology, solar water vapor generation systems are currently the most promising photothermal conversion systems. However, they still face numerous challenges in wastewater treatment. For example, many compounds and pollutants in wastewater can accumulate at the evaporator interface, degrading the water evaporation process or evaporating along with the steam, contaminating the condensate. Therefore, introducing pollutant removal technologies into the water evaporation process can improve the quality of the collected water and inject new vitality into solar evaporation technology. In photocatalytic reactions, solar energy is converted into chemical energy to degrade pollutants, while in solar-driven water evaporation, solar energy is converted into thermal energy, driving efficient water evaporation. With the assistance of sunlight, solar water evaporation technology excites electrons and holes to undergo a reduction-oxidation reaction, generating reactive oxygen species, which, in the photocatalytic process, decompose organic pollutants into harmless carbon dioxide and water. Furthermore, by providing high kinetic energy to generate reactive oxides, a localized photothermal effect is generated at the catalyst interface, which can improve photodegradation efficiency and has therefore attracted considerable attention from those skilled in the art.

[0003] Currently, reports on wastewater treatment include the patented technology "A Method for Preparing Graphene Hydrogel and Its Application in Wastewater Treatment" (CN 108516539A). This technology uses silver sulfide quantum dots containing rich functional groups as a reducing agent and crosslinking agent to reduce graphene oxide sheets and form them into a three-dimensional porous graphene hydrogel. The patented technology "A Method for Preparing Biomass Composite Hydrogel for Solar-Efficient Water Purification" (CN 114805851 A) involves mixing a chitosan solution with a polyvinyl alcohol solution, sequentially adding an initiator and a crosslinking agent to the mixed solution to produce a chitosan / polyvinyl alcohol hydrogel. The resulting hydrogel is then poured onto a loofah foam to produce the loofah-based chitosan / polyvinyl alcohol composite hydrogel.

[0004] The organic wastewater treatment material produced using this patented technology is complex to prepare, requires a wide variety of raw materials, and is costly. In actual wastewater treatment, pollutants in the wastewater settle on the surface of the material, hindering the upward flow of water. The organic matter degradation efficiency after 10 days of use is less than 80%. Summary of the Invention

[0005] The present invention aims to overcome the defects of the prior art and aims to provide a method for preparing a composite foam hydrogel organic sewage purifier with simple process, low cost and long service life; the composite foam hydrogel organic sewage purifier prepared by the method has high water evaporation efficiency and organic matter degradation efficiency.

[0006] To achieve the above object, the technical solution adopted by the present invention comprises the following steps:

[0007] Step 1: Add 20 to 50 parts by mass of urea and 0.1 to 0.5 parts by mass of carbon black to 100 parts by mass of deionized water, stir at 180 to 220 r / min for 40 to 60 minutes, then dry at 80 to 100°C for 18 to 24 hours, and then heat to 550 to 600°C at a rate of 1 to 4°C / min in a nitrogen atmosphere, and keep warm for 2 to 3 hours; then centrifuge and wash with deionized water, filter, and obtain a carbon black composite g-C3N4 photocatalytic reagent.

[0008] Step 2: Add 6 to 12 parts by mass of polyvinyl alcohol to 100 parts by mass of deionized water, and stir at 95 to 105° C. and 800 to 1000 r / min for 30 to 60 minutes; then add 4 to 10 parts by mass of agar powder and 0.8 to 1.4 parts by mass of the carbon black composite g-C3N4 photocatalytic agent, and stir at 95 to 105° C. and 800 to 1000 r / min for 30 to 60 minutes; then add 2 to 2.5 parts by mass of sodium dodecyl sulfate, 2 to 2.5 parts by mass of dodecanol and 2 to 2.5 parts by mass of gum arabic, and stir at 40 to 60° C. and 1500 to 2000 r / min for 20 to 30 minutes to obtain a composite foam hydrogel slurry.

[0009] Step 3: casting the composite foam hydrogel slurry into a mold, and freeze-drying it for 12 to 24 hours to obtain a composite foam hydrogel; the composite foam hydrogel is a block.

[0010] Step 4: Add 3 to 6 parts by mass of carnauba wax and 1 to 2 parts by mass of beeswax to 200 parts by mass of anhydrous ethanol, stir for 2 to 3 hours at 70 to 95°C and 800 to 1000 r / min, cool to room temperature, and then ultrasonically treat for 2 to 4 hours to obtain a hydrophobic mixed wax suspension.

[0011] Step 5: spraying the hydrophobic mixed wax suspension onto a large flat surface of the composite foam hydrogel block, and freeze-drying for 12 to 24 hours; obtaining a composite foam hydrogel organic sewage purifier.

[0012] The average molecular weight of the polyvinyl alcohol is 20,000-150,000, and the alcoholysis degree is one of 50%, 78%, 88% and 98%.

[0013] The particle size of the carbon black is 10 to 500 nm.

[0014] The freeze-drying temperature is -90 to -70°C.

[0015] The spraying process parameters are as follows: the nozzle diameter of the spray gun is 0.5-0.8 mm, the exhaust pressure of the spray gun is 40-50 psi, the moving speed of the spray gun is 1.5-2.5 cm / s, and the spraying amount of the hydrophobic mixed wax suspension is 50-150 mL / m 2 , each spraying time is 1 to 2.5 seconds.

[0016] Due to the adoption of the above technical solution, the present invention has the following advantages compared with the prior art:

[0017] (1) The main raw materials required for the present invention are urea, polyvinyl alcohol, agar powder, carbon black, sodium lauryl sulfate, lauryl alcohol, gum arabic, carnauba wax and beeswax. The types of materials used are relatively small and the sources are wide. The raw materials do not need special treatment during the preparation process of the composite foam hydrogel organic sewage purifier, and the cost is low.

[0018] (2) The composite foam hydrogel organic wastewater purifier prepared by the present invention not only possesses the water transport channels and free water activation capabilities inherent in existing hydrogels, i.e., excellent water transport performance, but also possesses a multi-network composite support structure and excellent mechanical strength. After loading the carbon black composite g-C3N4 photocatalytic agent, it can simultaneously perform photothermal water evaporation and organic matter degradation.

[0019] (3) The present invention sprays a hydrophobic enhancer on one surface of the prepared composite foam hydrogel to construct a Janus structure, so that the "organic sewage purifier" exhibits the characteristics of a hydrophobic upper layer and a hydrophilic lower layer. This Janus structure allows the hydrogel to float on the water surface to degrade organic matter. The hydrophobic property of the upper surface can effectively prevent the deposition of various pollutants, significantly improving the water evaporation and photocatalytic efficiency of the composite foam hydrogel organic sewage purifier. After 10 days of recycling, it can still maintain an organic matter degradation efficiency of more than 90%.

[0020] The present invention sprays a hydrophobic enhancer on one surface of the prepared composite foam hydrogel to construct a Janus structure, so that the "organic sewage purifier" exhibits the characteristics of a hydrophobic upper layer and a hydrophilic lower layer. This Janus structure enables the hydrogel to float on the water surface to degrade organic matter. The hydrophobic property of the upper surface can effectively prevent the deposition of various inorganic salts, significantly improving the water evaporation and photocatalytic efficiency of the composite foam hydrogel organic sewage purifier. After 10 days of recycling, the organic matter degradation efficiency can still maintain more than 90%.

[0021] The composite foam hydrogel organic sewage purifier prepared by the present invention has been tested: at 1KW / m 2 The water evaporation efficiency under sunlight intensity is 1.03-1.24 kg·m -2 ·h -1The degradation rate in two hours is 90.8-96.4%. The water evaporation efficiency and photothermal conversion efficiency are high.

[0022] Therefore, the process of the present invention is simple and the cost is low; the prepared composite foam hydrogel organic sewage purifier not only has a long service life, but also has high water evaporation efficiency and organic matter degradation efficiency. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with specific embodiments, which does not limit the scope of protection thereof.

[0024] A composite foam hydrogel organic sewage purifier and its preparation method. The preparation method described in this specific embodiment is:

[0025] Step 1: Add 20 to 50 parts by mass of urea and 0.1 to 0.5 parts by mass of carbon black to 100 parts by mass of deionized water, stir at 180 to 220 r / min for 40 to 60 minutes, then dry at 80 to 100°C for 18 to 24 hours, and then heat to 550 to 600°C at a rate of 1 to 4°C / min in a nitrogen atmosphere, and keep warm for 2 to 3 hours; then centrifuge and wash with deionized water, filter, and obtain a carbon black composite g-C3N4 photocatalytic reagent.

[0026] Step 2: Add 6 to 12 parts by mass of polyvinyl alcohol to 100 parts by mass of deionized water, and stir at 95 to 105° C. and 800 to 1000 r / min for 30 to 60 minutes; then add 4 to 10 parts by mass of agar powder and 0.8 to 1.4 parts by mass of the carbon black composite g-C3N4 photocatalytic agent, and stir at 95 to 105° C. and 800 to 1000 r / min for 30 to 60 minutes; then add 2 to 2.5 parts by mass of sodium dodecyl sulfate, 2 to 2.5 parts by mass of dodecanol and 2 to 2.5 parts by mass of gum arabic, and stir at 40 to 60° C. and 1500 to 2000 r / min for 20 to 30 minutes to obtain a composite foam hydrogel slurry.

[0027] Step 3: casting the composite foam hydrogel slurry into a mold, and freeze-drying it for 12 to 24 hours to obtain a composite foam hydrogel; the composite foam hydrogel is a block.

[0028] Step 4: Add 3 to 6 parts by mass of carnauba wax and 1 to 2 parts by mass of beeswax to 200 parts by mass of anhydrous ethanol, stir for 2 to 3 hours at 70 to 95°C and 800 to 1000 r / min, cool to room temperature, and then ultrasonically treat for 2 to 4 hours to obtain a hydrophobic mixed wax suspension.

[0029] Step 5: spraying the hydrophobic mixed wax suspension onto a large flat surface of the composite foam hydrogel block, and freeze-drying for 12 to 24 hours; obtaining a composite foam hydrogel organic sewage purifier.

[0030] The alcoholysis degree of the polyvinyl alcohol is one of 50%, 78%, 88% and 98%.

[0031] The freeze-drying temperature is -90 to -70°C.

[0032] The spraying process parameters are as follows: the nozzle diameter of the spray gun is 0.5-0.8 mm, the exhaust pressure of the spray gun is 40-50 psi, the moving speed of the spray gun is 1.5-2.5 cm / s, and the spraying amount of the hydrophobic mixed wax suspension is 50-150 mL / m 2 , each spraying time is 1 to 2.5 seconds.

[0033] In this specific implementation mode:

[0034] The average molecular weight of the polyvinyl alcohol is 20,000 to 150,000;

[0035] The particle size of the carbon black is 10 to 500 nm.

[0036] The details will not be described in detail in the embodiments.

[0037] Example 1

[0038] A composite foam hydrogel organic sewage purifier and its preparation method. The preparation method described in this embodiment is:

[0039] Step 1: Add 20 parts by mass of urea and 0.1 parts by mass of carbon black to 100 parts by mass of deionized water, stir at 180 r / min for 40 minutes, then dry at 80°C for 18 hours, and then heat to 550°C at a rate of 1°C / min in a nitrogen atmosphere, and keep warm for 2 hours; then centrifuge and wash with deionized water, filter, and obtain a carbon black composite g-C3N4 photocatalytic reagent.

[0040] Step 2: Add 6 parts by mass of polyvinyl alcohol to 100 parts by mass of deionized water, and stir at 95°C and 800r / min for 30 minutes; then add 4 parts by mass of agar powder and 0.8 parts by mass of the carbon black composite g-C3N4 photocatalytic agent, and stir at 95°C and 800r / min for 30 minutes; then add 2 parts by mass of sodium dodecyl sulfate, 2 parts by mass of dodecyl alcohol and 2 parts by mass of gum arabic, and stir at 40°C and 1500r / min for 20 minutes to obtain a composite foam hydrogel slurry.

[0041] Step 3: casting the composite foam hydrogel slurry into a mold, and freeze-drying it for 12 hours to obtain a composite foam hydrogel; the composite foam hydrogel is a block.

[0042] Step 4: Add 3 parts by mass of carnauba wax and 1 part by mass of beeswax to 200 parts by mass of anhydrous ethanol, stir at 70°C and 800 r / min for 2 hours, cool to room temperature, and then ultrasonically treat for 2 hours to obtain a hydrophobic mixed wax suspension.

[0043] Step 5: spraying the hydrophobic mixed wax suspension onto a large flat surface of the composite foam hydrogel block, and freeze-drying for 12 hours; obtaining a composite foam hydrogel organic sewage purifier.

[0044] The alcoholysis degree of the polyvinyl alcohol is 50%.

[0045] The freeze-drying temperature is -90°C.

[0046] The spraying process parameters are as follows: the nozzle diameter of the spray gun is 0.5 mm, the exhaust pressure of the spray gun is 40 psi, the moving speed of the spray gun is 1.5 cm / s, and the spraying amount of the hydrophobic wax suspension is 50 mL / m 2 , each spraying time is 1s.

[0047] The composite foam hydrogel organic sewage purifier prepared in Example 1 was tested: at 1KW / m 2 The water evaporation efficiency under sunlight intensity is 1.03 kg·m -2 ·h -1 ; The organic matter degradation rate in two hours was 90.8%.

[0048] Example 2

[0049] A composite foam hydrogel organic sewage purifier and its preparation method. The preparation method described in this embodiment is:

[0050] Step 1: Add 30 parts by mass of urea and 0.2 parts by mass of carbon black to 100 parts by mass of deionized water, stir at 190 r / min for 50 minutes, then dry at 85°C for 20 hours, and then heat to 560°C at a rate of 2°C / min in a nitrogen atmosphere, and keep warm for 2.4 hours; then centrifuge and wash with deionized water, filter, and obtain a carbon black composite g-C3N4 photocatalytic reagent.

[0051] Step 2: Add 8 parts by mass of polyvinyl alcohol to 100 parts by mass of deionized water, and stir at 98°C and 850r / min for 40 minutes; then add 6 parts by mass of agar powder and 1.0 parts by mass of the carbon black composite g-C3N4 photocatalytic agent, and stir at 98°C and 850r / min for 40 minutes; then add 2.2 parts by mass of sodium dodecyl sulfate, 2.2 parts by mass of dodecanol and 2.2 parts by mass of gum arabic, and stir at 45°C and 1600r / min for 23 minutes to obtain a composite foam hydrogel slurry.

[0052] Step 3: casting the composite foam hydrogel slurry into a mold, and freeze-drying it for 16 hours to obtain a composite foam hydrogel; the composite foam hydrogel is a block.

[0053] Step 4: Add 4 parts by mass of carnauba wax and 1.2 parts by mass of beeswax to 200 parts by mass of anhydrous ethanol, stir at 75°C and 850 r / min for 2.2 hours, cool to room temperature, and then ultrasonically treat for 2.5 hours to obtain a hydrophobic mixed wax suspension.

[0054] Step 5: spraying the hydrophobic mixed wax suspension onto a large flat surface of the composite foam hydrogel block, and freeze-drying for 16 hours; obtaining a composite foam hydrogel organic sewage purifier.

[0055] The alcoholysis degree of the polyvinyl alcohol is 78%.

[0056] The freeze-drying temperature is -80°C.

[0057] The spraying process parameters are as follows: the nozzle diameter of the spray gun is 0.6 mm, the exhaust pressure of the spray gun is 44 psi, the moving speed of the spray gun is 1.9 cm / s, and the spraying amount of the hydrophobic mixed wax suspension is 75 mL / m 2 , each spraying time is 1.5s.

[0058] The composite foam hydrogel organic sewage purifier prepared in Example 2 was tested: at 1KW / m 2 The water evaporation efficiency under sunlight intensity is 1.11 kg·m -2 ·h -1 ; The organic matter degradation rate in two hours was 93.5%.

[0059] Example 3

[0060] A composite foam hydrogel organic sewage purifier and its preparation method. The preparation method described in this embodiment is:

[0061] Step 1: Add 40 parts by mass of urea and 0.3 parts by mass of carbon black to 100 parts by mass of deionized water, stir at 200 r / min for 55 minutes, then dry at 90°C for 22 hours, and then heat to 570°C at a rate of 3°C / min and a nitrogen atmosphere, and keep warm for 2.8 hours; then centrifuge and wash with deionized water, filter, and obtain a carbon black composite g-C3N4 photocatalytic reagent.

[0062] Step 2: Add 10 parts by mass of polyvinyl alcohol to 100 parts by mass of deionized water, and stir at 102°C and 900r / min for 50min; then add 8 parts by mass of agar powder and 1.2 parts by mass of the carbon black composite g-C3N4 photocatalytic agent, and stir at 102°C and 900r / min for 50min; then add 2.3 parts by mass of sodium dodecyl sulfate, 2.3 parts by mass of dodecyl alcohol and 2.3 parts by mass of gum arabic, and stir at 50°C and 1700r / min for 25min to obtain a composite foam hydrogel slurry.

[0063] Step 3: casting the composite foam hydrogel slurry into a mold, and freeze-drying it for 20 hours to obtain a composite foam hydrogel; the composite foam hydrogel is a block.

[0064] Step 4: Add 5 parts by mass of carnauba wax and 1.5 parts by mass of beeswax to 200 parts by mass of anhydrous ethanol, stir at 80°C and 900 r / min for 2.5 hours, cool to room temperature, and then ultrasonically treat for 3.0 hours to obtain a hydrophobic mixed wax suspension.

[0065] Step 5: spraying the hydrophobic mixed wax suspension onto a large flat surface of the composite foam hydrogel block, and freeze-drying for 20 hours; obtaining a composite foam hydrogel organic sewage purifier.

[0066] The alcoholysis degree of the polyvinyl alcohol is 88%.

[0067] The freeze-drying temperature is -75°C.

[0068] The spraying process parameters are as follows: the nozzle diameter of the spray gun is 0.7 mm, the exhaust pressure of the spray gun is 47 psi, the moving speed of the spray gun is 2.3 cm / s, and the spraying amount of the hydrophobic wax suspension is 100 mL / m 2 , each spraying time is 2.0s.

[0069] The composite foam hydrogel organic sewage purifier prepared in Example 3 was tested: at 1KW / m 2 The water evaporation efficiency under sunlight intensity is 1.18 kg·m -2 ·h -1 ; The organic matter degradation rate in two hours was 94.2%.

[0070] Example 4

[0071] A composite foam hydrogel organic sewage purifier and its preparation method. The preparation method described in this embodiment is:

[0072] Step 1: Add 50 parts by mass of urea and 0.5 parts by mass of carbon black to 100 parts by mass of deionized water, stir at 220 r / min for 60 minutes, then dry at 100°C for 24 hours, and then heat to 600°C at a rate of 4°C / min in a nitrogen atmosphere, and keep warm for 3.0 hours; then centrifuge and wash with deionized water, filter, and obtain a carbon black composite g-C3N4 photocatalytic reagent.

[0073] Step 2: Add 12 parts by mass of polyvinyl alcohol to 100 parts by mass of deionized water, and stir at 105°C and 1000r / min for 60min; then add 10 parts by mass of agar powder and 1.4 parts by mass of the carbon black composite g-C3N4 photocatalytic agent, and stir at 105°C and 1000r / min for 60min; then add 2.5 parts by mass of sodium dodecyl sulfate, 2.5 parts by mass of dodecanol and 2.5 parts by mass of gum arabic, and stir at 60°C and 2000r / min for 30min to obtain a composite foam hydrogel slurry.

[0074] Step 3: casting the composite foam hydrogel slurry into a mold, and freeze-drying it for 24 hours to obtain a composite foam hydrogel; the composite foam hydrogel is a block.

[0075] Step 4: Add 6 parts by mass of carnauba wax and 2 parts by mass of beeswax to 200 parts by mass of anhydrous ethanol, stir at 95°C and 1000 r / min for 3 hours, cool to room temperature, and then ultrasonically treat for 4.0 hours to obtain a hydrophobic mixed wax suspension.

[0076] Step 5: spraying the hydrophobic mixed wax suspension onto a large flat surface of the composite foam hydrogel block, and freeze-drying for 24 hours; obtaining a composite foam hydrogel organic sewage purifier.

[0077] The alcoholysis degree of the polyvinyl alcohol is 98%.

[0078] The freeze-drying temperature is -70°C.

[0079] The spraying process parameters are as follows: the nozzle diameter of the spray gun is 0.8 mm, the exhaust pressure of the spray gun is 50 psi, the moving speed of the spray gun is 2.5 cm / s, and the spraying amount of the hydrophobic wax suspension is 150 mL / m 2 , each spraying time is 2.5s.

[0080] The composite foam hydrogel organic sewage purifier prepared in Example 4 was tested: at 1KW / m 2 The water evaporation efficiency under sunlight intensity is 1.24 kg·m -2 ·h -1 ; The organic matter degradation rate in two hours was 96.4%.

[0081] Compared with the prior art, this embodiment has the following advantages:

[0082] (1) The main raw materials required for this specific embodiment are urea, polyvinyl alcohol, agar powder, carbon black, sodium lauryl sulfate, lauryl alcohol, gum arabic, carnauba wax and beeswax. The types of materials used are relatively small and the sources are wide. The raw materials do not need special treatment during the preparation process of the composite foam hydrogel organic sewage purifier, and the cost is low.

[0083] (2) The composite foam hydrogel organic wastewater purifier prepared in this embodiment not only possesses the water transport channels and free water activation capabilities inherent in existing hydrogels, i.e., excellent water transport performance, but also possesses a multi-network composite support structure and excellent mechanical strength. After loading the carbon black composite g-C3N4 photocatalytic agent, it can simultaneously perform photothermal evaporation and organic matter degradation.

[0084] (3) In this specific embodiment, a hydrophobic enhancer is sprayed on one surface of the prepared composite foam hydrogel to construct a Janus structure, so that the "organic sewage purifier" exhibits the characteristics of a hydrophobic upper layer and a hydrophilic lower layer. This Janus structure allows the hydrogel to float on the water surface to degrade organic matter. The hydrophobic property of the upper surface can effectively avoid the deposition of various pollutants, significantly improving the water evaporation and photocatalytic efficiency of the composite foam hydrogel organic sewage purifier. After 10 days of recycling, it can still maintain an organic matter degradation efficiency of more than 90%.

[0085] (4) This specific embodiment uses in-situ foaming technology to quickly and easily construct a composite foam hydrogel matrix with a network interpenetrating structure, which greatly improves the ability of the composite foam hydrogel matrix material to transport water and gas. By embedding a carbon black composite g-C3N4 photocatalytic agent in the network structure of the composite foam hydrogel matrix, organic pollutants in the water are degraded, while also avoiding the deposition of organic matter on the composite foam hydrogel matrix, significantly improving the water evaporation efficiency of the composite foam hydrogel organic wastewater purifier. The slurry injection molding technology not only meets the use requirements of different environments, but also can be used for large-scale production applications.

[0086] The composite foam hydrogel organic sewage purifier prepared in this embodiment has been tested: at 1KW / m 2 The water evaporation efficiency under sunlight intensity is 1.03-1.24 kg·m-2 ·h -1 The degradation rate in two hours is 90.8-96.4%. The water evaporation efficiency and photothermal conversion efficiency are high.

[0087] Therefore, the present embodiment has a simple process and low cost; the prepared composite foam hydrogel organic sewage purifier not only has a long service life, but also has high water evaporation efficiency and organic matter degradation efficiency.

Claims

1. A method for preparing a composite foam hydrogel organic sewage purifier, characterized in that The preparation method is: Step 1, adding 20-50 parts by mass of urea and 0.1-0.5 parts by mass of carbon black to 100 parts by mass of deionized water, stirring at 180-220 r / min for 40-60 minutes, then drying at 80-100°C for 18-24 hours, then heating to 550-600°C at a rate of 1-4°C / min in a nitrogen atmosphere, and keeping warm for 2-3 hours; then centrifugally washing with deionized water, filtering, and obtaining a carbon black composite g-C3N4 photocatalytic reagent; Step 2, adding 6 to 12 parts by mass of polyvinyl alcohol to 100 parts by mass of deionized water, stirring at 95 to 105 ° C and 800 to 1000 r / min for 30 to 60 minutes; then adding 4 to 10 parts by mass of agar powder and 0.8 to 1.4 parts by mass of the carbon black composite g-C3N4 photocatalytic agent, stirring at 95 to 105 ° C and 800 to 1000 r / min for 30 to 60 minutes; then adding 2 to 2.5 parts by mass of sodium dodecyl sulfate, 2 to 2.5 parts by mass of dodecanol and 2 to 2.5 parts by mass of gum arabic, stirring at 40 to 60 ° C and 1500 to 2000 r / min for 20 to 30 minutes to obtain a composite foam hydrogel slurry; Step 3: casting the composite foam hydrogel slurry into a mold, and freeze-drying it for 12 to 24 hours to obtain a composite foam hydrogel; the composite foam hydrogel is a block; Step 4: Add 3 to 6 parts by mass of carnauba wax and 1 to 2 parts by mass of beeswax to 200 parts by mass of anhydrous ethanol, stir at 70 to 95° C. and 800 to 1000 r / min for 2 to 3 hours, cool to room temperature, and then ultrasonicate for 2 to 4 hours to obtain a hydrophobic mixed wax suspension; Step 5: spraying the hydrophobic mixed wax suspension onto a large flat surface of the composite foam hydrogel block, and freeze-drying for 12 to 24 hours to obtain a composite foam hydrogel organic wastewater purifier; The spraying process parameters are as follows: the nozzle diameter of the spray gun is 0.5-0.8 mm, the exhaust pressure of the spray gun is 40-50 psi, the moving speed of the spray gun is 1.5-2.5 cm / s, and the spraying amount of the hydrophobic wax suspension is 50-150 mL / m 2 , each spraying time is 1~2.5s.

2. The preparation method of the composite foam hydrogel organic sewage purifier according to claim 1, characterized in that The average molecular weight of the polyvinyl alcohol is 20,000-150,000, and the alcoholysis degree is one of 50%, 78%, 88% and 98%.

3. The preparation method of the composite foam hydrogel organic sewage purifier according to claim 1, characterized in that The particle size of the carbon black is 10-500 nm.

4. The preparation method of the composite foam hydrogel organic sewage purifier according to claim 1, characterized in that The freeze-drying temperature is -90 to -70°C.

5. A composite foam hydrogel organic sewage purifier, characterized in that The composite foam hydrogel organic sewage purifier is a composite foam hydrogel organic sewage purifier prepared according to the preparation method of the composite foam hydrogel organic sewage purifier according to any one of claims 1 to 4.