Oily wastewater adsorption material as well as preparation method and application thereof

Abstract

The invention provides an oily wastewater adsorption material as well as a preparation method and application thereof. The oily wastewater adsorption material comprises more than two adsorption layers which are stacked, in the thickness direction of the oil-containing wastewater adsorption material, the water contact angle of the oil-containing wastewater adsorption material is gradually increased or decreased layer by layer; each adsorption layer is a modified polypropylene fiber layer; and staggered through holes are respectively formed in each adsorption layer. According to the oily wastewater adsorbing material provided by the invention, the adsorbing layers with different hydrophilic and oleophylic properties due to different water contact angles are arranged, so that the hydrophilic and oleophylic properties of the adsorbing material required due to the change of the concentration of the oily organic pollutants in water are effectively adapted; the adsorption and removal effects on oil organic pollutants with different concentrations and different states are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and particularly relates to an oil-containing wastewater adsorption material, a preparation method thereof, and an application thereof. Background Art

[0002] Oil is one of the important energy sources on which human beings depend for survival and development. Inevitably, a large amount of wastewater containing oil-based organic pollutants will be generated during its exploration, extraction, refining, processing, transportation, etc. The oil-based organic pollutants in the wastewater commonly include: one is animal fat and vegetable oil, etc., which are composed of triglycerides formed by fatty acids or glycerol with different chain lengths; the other is the liquid component of crude oil or mineral oil. Crude oil is a mixture of hydrocarbons, that is, all hydrocarbons are composed of straight-chain or branched-chain hydrocarbons in a ring structure. If these wastewaters directly enter the environment, it will cause serious damage to the ecosystem. At present, the main methods for treating wastewater containing oil-based organic pollutants include gravity separation, air flotation method, adsorption method, etc. Although gravity separation and air flotation method have certain treatment effects, they mainly target high-concentration oil-based organic pollutants, and the equipment occupies a large area and has high investment and operation costs. The adsorption method plays an important role in the treatment of sewage and wastewater. By using the adsorption characteristics of the adsorption material, pollutants can be effectively adsorbed and enriched to remove pollutants, achieving the purpose of purifying wastewater.

[0003] At present, the commonly used adsorption materials for treating wastewater containing oil-based organic pollutants include oil-absorbing felts, oil-absorbing cotton, oil-absorbing ropes, etc. However, these adsorption materials have good adsorption effects on pure oil or large amounts of concentrated surface floating oil, but have extremely poor effects on floating oil with low oil content and dispersed, emulsified, and dissolved oil-based organic pollutant wastewaters. Even for pure oil or large amounts of concentrated surface floating oil, its concentration will continuously decrease during the treatment process, and at this time, traditional adsorption materials are difficult to play an effective role. Summary of the Invention

[0004] The purpose of the present invention is to provide an oil-containing wastewater adsorption material, a preparation method thereof, and an application thereof. The oil-containing wastewater adsorption material provided by the present invention has good treatment ability for oil-based organic pollutants in different states.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides an oil-containing wastewater adsorption material, which includes two or more adsorption layers arranged in a stacked manner; along the thickness direction of the oil-containing wastewater adsorption material, the water contact angle of the oil-containing wastewater adsorption material gradually increases or decreases layer by layer; each adsorption layer is a modified polypropylene fiber layer; through holes are respectively arranged on each adsorption layer in a staggered manner.

[0007] Preferably, the thickness of each adsorption layer is independently 1-10 mm.

[0008] Preferably, the maximum water contact angle of the adsorption layer is 125°-145°, and the minimum water contact angle of the adsorption layer is 60°-85°.

[0009] Preferably, the diameter of the polypropylene fibers in the modified polypropylene fiber layer is 1-5 μm.

[0010] Preferably, the oil-containing wastewater adsorption material includes a first adsorption layer, a second adsorption layer, and a third adsorption layer that are stacked in sequence.

[0011] Preferably, the water contact angle of the first adsorption layer is 125°-145°, the water contact angle of the second adsorption layer is 90°-120°, and the water contact angle of the third adsorption layer is 60°-85°.

[0012] Preferably, the adsorption layers are connected by heating fusion or spot welding.

[0013] The present invention also provides a preparation method of the oil-containing wastewater adsorption material described in the above technical solution, including the following steps:

[0014] (1) Graft-modify the polypropylene fiber layer respectively to obtain adsorption layers with different water contact angles; through holes are provided in the adsorption layers with different water contact angles;

[0015] (2) Stack the adsorption layers with different water contact angles obtained in step (1) in the order of increasing or decreasing water contact angle layer by layer, and after fixed connection, obtain the oil-containing wastewater adsorption material.

[0016] Preferably, the graft-modification method in step (1) includes one or more of solution grafting, suspension grafting, plasma grafting, and blend modification.

[0017] The present invention also provides the application of the oil-containing wastewater adsorption material described in the above technical solution or the oil-containing wastewater adsorption material prepared by the preparation method described in the above technical solution in treating oil-containing organic pollutant wastewater.

[0018] The present invention provides an oil-containing wastewater adsorption material, which includes two or more adsorption layers arranged in a stacked manner; along the thickness direction of the oil-containing wastewater adsorption material, the water contact angle of the oil-containing wastewater adsorption material increases or decreases layer by layer; each adsorption layer is a modified polypropylene fiber layer; through holes are respectively arranged on each adsorption layer in a staggered manner. Each adsorption layer of the oil-containing wastewater adsorption material provided by the present invention is a modified polypropylene fiber layer, which has certain oil absorption performance itself and can improve the adsorption ability for oil-containing wastewater; the water contact angle of the oil-containing wastewater adsorption material provided by the present invention increases or decreases layer by layer. When treating wastewater, the oil-containing wastewater contacts the side with the largest water contact angle of the oil-containing wastewater adsorption material, and the water contact angle of each adsorption layer decreases successively when passing through the oil-containing wastewater adsorption material, which can strengthen the collision between the oil-containing organic pollutants and the oil absorption layer, re-adsorb and remove low-concentration oil organic pollutants such as surface floating oil in the wastewater, and improve the adsorption ability for oil-containing organic pollutants; by respectively arranging through holes in a staggered manner on the adsorption layer, the wastewater to be treated can pass through the adsorption layer layer by layer. The results of the examples show that when the oil-containing wastewater adsorption material provided by the present invention is used to adsorb oil organic pollutant wastewater, the concentration of the oil organic pollutant wastewater with a concentration of 420 mg / L is reduced to 5 mg / L after being adsorbed by the first adsorption layer, the second adsorption layer and the third adsorption layer in sequence, indicating that the oil-containing wastewater adsorption material provided by the present invention has good oil removal ability for organic pollutant wastewater with a low oil content. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of the oil-containing wastewater adsorption material provided by the present invention. Detailed Embodiments

[0020] The present invention provides an oil-containing wastewater adsorption material, which includes two or more adsorption layers arranged in a stacked manner; along the thickness direction of the oil-containing wastewater adsorption material, the water contact angle of the oil-containing wastewater adsorption material increases or decreases layer by layer; each adsorption layer is a modified polypropylene fiber layer; through holes are respectively arranged on each adsorption layer in a staggered manner.

[0021] The oil-containing wastewater adsorption material provided by the present invention includes two or more adsorption layers arranged in a stacked manner.

[0022] In the present invention, along the thickness direction of the oil-containing wastewater adsorption material, the water contact angle of the oil-containing wastewater adsorption material increases or decreases layer by layer. The water contact angle of the oil-containing wastewater adsorption material provided by the present invention increases or decreases layer by layer. When treating wastewater, the oil-containing wastewater contacts the side with the largest water contact angle of the oil-containing wastewater adsorption material, and the water contact angle of each adsorption layer decreases successively when passing through the oil-containing wastewater adsorption material, which can strengthen the collision between the oil-containing organic pollutants and the oil absorption layer, re-adsorb and remove low-concentration oil organic pollutants such as surface floating oil in the wastewater, and improve the adsorption ability for oil-containing organic pollutants.

[0023] In the present invention, the maximum water contact angle of the adsorption layer is preferably 125° to 145°, more preferably 132° to 140°; the minimum water contact angle of the adsorption layer is preferably 60° to 85°, more preferably 68° to 77°. By controlling the maximum and minimum water contact angles of the adsorption layer within the above ranges in the present invention, it is more beneficial to improve the treatment ability for oily organic wastewater.

[0024] In the present invention, the adsorption layer of the oily wastewater adsorption material preferably has three layers, and more preferably includes a first adsorption layer, a second adsorption layer, and a third adsorption layer which are sequentially stacked. In the present invention, the water contact angle of the first adsorption layer is preferably 125° to 145°, more preferably 132° to 140°; the water contact angle of the second adsorption layer is preferably 90° to 120°, more preferably 102° to 109°; the water contact angle of the third adsorption layer is preferably 60° to 85°, more preferably 68° to 77°. By using the above oily wastewater adsorption material in the present invention, efficient treatment of organic pollutant wastewater with low oil content can be achieved.

[0025] In the present invention, each adsorption layer is a modified polypropylene fiber layer. By using the modified polypropylene fiber layer as the adsorption layer in the present invention, it has the ability to adsorb oily organic substances, and can improve the treatment ability of the oily wastewater adsorption material for oily organic wastewater.

[0026] In the present invention, the diameter of the polypropylene fibers in the modified polypropylene fiber layer is preferably 1 to 5 μm, more preferably 2 to 4 μm. By using polypropylene fibers with the above diameters in the present invention, the adsorption layer has a larger specific surface area.

[0027] In the present invention, the thickness of each adsorption layer is independently preferably 1 to 10 mm, more preferably 5 to 8 mm. By using adsorption layers with the above thicknesses in the present invention, it is more beneficial to improve the treatment ability for oily organic wastewater.

[0028] In the present invention, misaligned through-holes are respectively provided on each adsorption layer. By respectively providing misaligned through-holes on each adsorption layer in the present invention, the wastewater containing adsorbed oily pollutants can be drained to the next adsorption layer. In the present invention, the through-holes serve a drainage function, so the present invention does not make special limitations on the density, diameter, and number of the through-holes, and they are adjusted according to the size of each adsorption layer and the efficiency of wastewater treatment required, as long as the through-holes of different layers can be misaligned. In the embodiments of the present invention, small holes arranged at equal distances and with misaligned openings are respectively provided on each adsorption layer, the density of the through-holes in each adsorption layer can be 1000 pieces / m 2 , the distance between adjacent through-holes in each adsorption layer can be 3 cm, and the diameter of the through-holes can be 2 mm.

[0029] In the present invention, the adsorption layers are connected by heating fusion or spot welding. By adopting the above method, the present invention can fixedly connect the adsorption layers, improving the stability in use.

[0030] In an embodiment of the present invention, the schematic diagram of the oil-containing wastewater adsorption material provided by the present invention is preferably as Figure 1 shown. In Figure 1 , 1 is the first adsorption layer; 2 is the second adsorption layer; 3 is the third adsorption layer; 4 is the through hole.

[0031] The present invention also provides a preparation method of the oil-containing wastewater adsorption material according to the above technical solution, including the following steps:

[0032] (1) Respectively graft-modify the polypropylene fiber layer to obtain adsorption layers with different water contact angles; through holes are provided in the adsorption layers with different water contact angles;

[0033] (2) Stack the adsorption layers with different water contact angles obtained in step (1) in the order of increasing or decreasing water contact angle layer by layer, and after fixed connection, an oil-containing wastewater adsorption material is obtained.

[0034] The present invention respectively graft-modifies the polypropylene fiber layer to obtain adsorption layers with different water contact angles; through holes are provided in the adsorption layers with different water contact angles.

[0035] The present invention has no special limitation on the source of the polypropylene fiber layer. A polypropylene fiber layer formed by interweaving conventional polypropylene fibers with a diameter of 1 - 5 μm can make the thickness of the polypropylene fiber layer reach 1 - 10 mm. In the present invention, the polypropylene fiber layer is preferably a polypropylene fiber layer made of polypropylene-based melt-blown fibers.

[0036] In the present invention, the graft-modification method preferably includes one or more of solution grafting, suspension grafting, plasma grafting, and blending modification. By adopting the above graft-modification method, the present invention can graft different groups on the polypropylene fiber layer, making the modified polypropylene fiber layer have different hydrophobicities and showing different water contact angles. In the present invention, the group is preferably at least one of hydroxyl, carboxyl, sulfonic acid group, amino group, silyl group, and fluoroalkyl group.

[0037] The present invention does not make special limitations on the methods and specific parameters of the solution grafting, suspension grafting, plasma grafting, and blending modification. By adjusting the methods and parameters of the conventional solution grafting, suspension grafting, plasma grafting, and blending modification, the water contact angle of the adsorption layer can reach the required range.

[0038] After obtaining the adsorption layers with different water contact angles, the present invention stacks the adsorption layers with different water contact angles in a manner where the water contact angles increase or decrease layer by layer in sequence. After fixed connection, an oil-containing wastewater adsorption material is obtained.

[0039] In the present invention, the method of fixed connection is preferably heat fusion or spot welding. The present invention has no special limitation on the method of heat fusion or spot welding. Using the conventional heat fusion or spot welding operation method, each layer of the adsorption layer can be fixedly connected.

[0040] The method provided by the present invention is simple to operate and can obtain an oil-containing wastewater adsorption material with good treatment ability for oil-containing organic wastewater.

[0041] The present invention also provides the application of the oil-containing wastewater adsorption material described in the above technical solution in treating oil-containing organic pollutant wastewater.

[0042] The present invention has no special limitation on the method of applying the oil-containing wastewater adsorption material in treating oil-containing organic pollutant wastewater. The method of using a conventional adsorption material to adsorb wastewater can be adopted. In the present invention, the method of applying the oil-containing wastewater adsorption material in treating oil-containing organic pollutant wastewater is preferably to filter the wastewater with the oil-containing wastewater adsorption material; when filtering, the adsorption layer with the largest water contact angle contacts the wastewater.

[0043] The present invention has no special limitation on the source of the oil-containing organic pollutant wastewater. Any conventional oil-containing organic pollutant wastewater can be used. In the present invention, the oil-containing organic pollutant wastewater is preferably the wastewater from the petrochemical industry. In the present invention, the oil content of the oil-containing organic pollutant wastewater is preferably 200 - 500 mg / L, more preferably 220 - 420 mg / L. The oil content of the oil-containing organic pollutant wastewater used in the present invention is within the above range, belonging to the oil-containing organic pollutant wastewater with a relatively low oil content. Since the oil-containing wastewater adsorption material provided by the present invention can strengthen the collision between pollutants and the oil-absorbing layer as the contact angle of each adsorption layer gradually decreases when the wastewater passes through the adsorption material, the low-concentration oil organic pollutants such as surface floating oil in the wastewater can be adsorbed and removed again.

[0044] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0045] Example 1

[0046] An oil-containing wastewater adsorption material is composed of three adsorption layers arranged in a stacked manner. Along the thickness direction of the oil-containing wastewater adsorption material, the material is the first adsorption layer, the second adsorption layer, and the third adsorption layer arranged in a stacked manner. The water contact angle of the first adsorption layer is 140°, the water contact angle of the second adsorption layer is 102°, and the water contact angle of the third adsorption layer is 77°. The thickness of each adsorption layer is 5 mm, and the material of each adsorption layer is a modified polypropylene fiber layer. The diameter of the polypropylene fibers in the polypropylene fiber layer of the modified polypropylene fiber layer is 1-5 μm. Small holes arranged at equal distances and with staggered openings are respectively provided on each adsorption layer. The distance between adjacent through holes in each adsorption layer is 3 cm, and the diameter of the through holes is 2 mm.

[0047] The preparation method of the above-mentioned oil-containing wastewater adsorption material is as follows:

[0048] (1) Graft silane groups onto the polypropylene matrix by plasma grafting to obtain the first adsorption layer made of polypropylene-based melt-blown fibers with a water contact angle of 140°. The method is as follows: Carry out surface activation treatment on the polypropylene melt-blown fibers under the conditions of a plasma atmosphere pressure of 30 Pa, a discharge power of 15 W, and a discharge time of 5 min. Subsequently, carry out grafting reaction for 3 h under the conditions of a reaction temperature of 50 °C and a concentration of silane group monomers of 10% to obtain the first adsorption layer, in which through holes are provided.

[0049] Graft carboxyl groups onto the polypropylene matrix by plasma grafting to obtain the second adsorption layer made of polypropylene-based melt-blown fibers with a water contact angle of 102°. The method is as follows: Carry out surface activation treatment on the polypropylene melt-blown fibers under the conditions of a plasma atmosphere pressure of 20 Pa, a discharge power of 15 W, and a discharge time of 3 min. Subsequently, carry out grafting reaction for 4 h under the conditions of a reaction temperature of 60 °C and a concentration of carboxyl group monomers of 30% to obtain the second adsorption layer, in which through holes are provided.

[0050] Graft sulfonic acid groups onto the polypropylene matrix by solution grafting to obtain the third adsorption layer made of polypropylene-based melt-blown fibers with a water contact angle of 77°. The method is as follows: Weigh a certain amount of polypropylene, add 2.5 mL / g of xylene and 8 wt% of 2,5-dimethyl-2,5-bishexane, and carry out grafting reaction at 140 °C for 55 min under the condition of a concentration of sulfonic acid group monomers of 20%. Then, obtain polypropylene-based melt-blown fibers by melt-blowing spinning, which is the third adsorption layer, in which through holes are provided.

[0051] (2) Stack the first adsorption layer, the second adsorption layer, and the third adsorption layer obtained in the step (1) in the order from top to bottom, and fix and connect them by heating and fusing to obtain the oil-containing wastewater adsorption material.

[0052] Example 2

[0053] An oil-containing wastewater adsorption material, which is composed of three adsorption layers stacked on top of each other; along the thickness direction of the oil-containing wastewater adsorption material, the oil-containing wastewater adsorption material is the first adsorption layer, the second adsorption layer and the third adsorption layer stacked on top of each other. The water contact angle of the first adsorption layer is 132°, the water contact angle of the second adsorption layer is 109°, and the water contact angle of the third adsorption layer is 68°; the thickness of each adsorption layer is 8 mm, and the material of each adsorption layer is a modified polypropylene fiber layer. The diameter of the polypropylene fibers in the polypropylene fiber layer of the modified polypropylene fiber layer is 1-5 μm; small holes arranged at equal intervals and with staggered openings are respectively provided on each adsorption layer. The distance between adjacent through holes in each adsorption layer is 3 cm, and the diameter of the through holes is 2 mm;

[0054] The preparation method of the above-mentioned oil-containing wastewater adsorption material is as follows:

[0055] (1) Graft fluoroalkyl groups onto the polypropylene matrix by means of blending modification to obtain the first adsorption layer made of polypropylene-based meltblown fibers with a water contact angle of 132°. The method is as follows: Mix polypropylene and 30 wt% fluoroalkyl monomer evenly, and perform blending modification in a twin-screw extruder. The temperatures of each section of the extruder are 140 °C, 170 °C, 170 °C, and 130 °C respectively, and then meltblown spinning is carried out to obtain polypropylene-based meltblown fibers, which are the first adsorption layer, and through holes are provided therein;

[0056] Graft hydroxyl groups onto the polypropylene matrix by means of suspension grafting to obtain the second adsorption layer made of polypropylene-based meltblown fibers with a water contact angle of 109°. The method is as follows: Weigh a certain amount of polypropylene, add 5 mL / g of deionized water, 10 wt% of xylene, and 0.4 wt% of benzoyl peroxide, and carry out grafting reaction at 90 °C for 3 h under the condition that the concentration of the hydroxyl group-containing monomer is 40%. Then meltblown spinning is carried out to obtain polypropylene-based meltblown fibers, which are the second adsorption layer, and through holes are provided therein;

[0057] Graft carboxyl groups and amino groups onto the polypropylene matrix by means of suspension grafting to obtain the third adsorption layer made of polypropylene-based meltblown fibers with a water contact angle of 68°. The method is as follows: Weigh a certain amount of polypropylene, add 2 mL / g of deionized water, 12 wt% of xylene, and 1 wt% of benzoyl peroxide, and carry out grafting reaction at 90 °C for 3 hours under the condition that the concentration of the carboxyl group-containing monomer is 50%. Then use dicyclohexylcarbodiimide and 1-hydroxybenzotriazole as condensation reagents to carry out condensation reaction with the amino group-containing monomer for 1 h. After meltblown spinning, polypropylene-based meltblown fibers are obtained, which are the third adsorption layer, and through holes are provided therein;

[0058] (2) Stack the first adsorption layer, the second adsorption layer and the third adsorption layer obtained in the step (1) in the order from top to bottom, and fix and connect them by heating and fusing to obtain the oil-containing wastewater adsorption material.

[0059] Comparative Example 1

[0060] A composite adsorption material for wastewater containing oily organic pollutants. The polypropylene matrix is grafted with fluoroalkyl groups by a blending modification method to obtain a first adsorption layer made of polypropylene-based melt-blown fibers with a water contact angle of 132°. The materials of the second adsorption layer and the third adsorption layer are the same as those of the first adsorption layer. Small holes arranged at equal intervals and with staggered openings are provided on the surfaces of the first adsorption layer and the second adsorption layer. The distance between adjacent through-holes in each adsorption layer is 3 cm, and the diameter of the through-holes is 2 mm. Each adsorption layer is connected by electric welding to obtain the adsorption material.

[0061] Comparative Example 2

[0062] A composite adsorption material for wastewater containing oily organic pollutants. The polypropylene matrix is grafted with fluoroalkyl groups by a blending modification method to obtain a first adsorption layer made of polypropylene-based melt-blown fibers with a water contact angle of 132°. The polypropylene matrix is grafted with hydroxyl groups by a suspension grafting method to obtain a second adsorption layer made of polypropylene-based melt-blown fibers with a water contact angle of 109°. The material of the third adsorption layer is the same as that of the second adsorption layer. Small holes arranged at equal intervals and with staggered openings are provided on the surfaces of the first adsorption layer and the second adsorption layer. The distance between adjacent through-holes in each adsorption layer is 3 cm, and the diameter of the through-holes is 2 mm. Each adsorption layer is connected by electric welding to obtain the adsorption material.

[0063] Application Example 1

[0064] The oily wastewater adsorption material prepared in Example 1 is used to filter the wastewater containing oily organic pollutants with a concentration of 420 mg / L. After the wastewater containing oily organic pollutants is adsorbed by the first adsorption layer, the second adsorption layer, and the third adsorption layer in sequence, the concentration of the oily organic pollutants is measured to be reduced to 5 mg / L.

[0065] Application Example 2

[0066] The oily wastewater adsorption material prepared in Example 2 is used to filter the wastewater containing oily organic pollutants with a concentration of 220 mg / L. After the wastewater containing oily organic pollutants is adsorbed by the first adsorption layer, the second adsorption layer, and the third adsorption layer in sequence, the concentration of the oily organic pollutants is measured to be reduced to 3 mg / L.

[0067] Comparative Application Example 1

[0068] The adsorption material prepared in Comparative Example 1 is used to filter the wastewater containing oily organic pollutants with a concentration of 220 mg / L. After the wastewater containing oily organic pollutants is adsorbed by the first adsorption layer, the second adsorption layer, and the third adsorption layer in sequence, the concentration of the oily organic pollutants is measured to be reduced to 40 mg / L.

[0069] Comparative Application Example 2

[0070] The adsorption material prepared in Comparative Example 2 was used to filter the oily organic pollutant wastewater with a concentration of 220 mg / L. After the oily organic pollutant wastewater was adsorbed by the first adsorption layer, the second adsorption layer, and the third adsorption layer in sequence, the concentration of the oily organic pollutant was reduced to 18 mg / L.

[0071] As can be seen from the above results, when the oily wastewater adsorption material provided by the present invention is used to treat the oily organic pollutant wastewater with a low oil content, it has excellent removal ability. This is because: when the wastewater containing oily organic pollutants flows through the first adsorption layer, the concentration of the oily organic pollutants in the wastewater is the highest at this time. When choosing polypropylene-based melt-blown fibers with a large water contact angle, that is, excellent lipophilic and hydrophobic properties, as the adsorption material of the first adsorption layer, the adsorption capacity for oily organic pollutants is large and the adsorption speed is fast. The adsorbed wastewater mainly enters the second adsorption layer through the through holes, and a small part of the wastewater enters the second adsorption layer through osmosis; at this time, the concentration of the oily organic pollutants in the wastewater decreases. When choosing polypropylene-based melt-blown fibers with a slightly lower water contact angle, that is, still good lipophilic properties but weakened hydrophobic properties, as the adsorption material of the second adsorption layer, strengthening the collision between the pollutants and the oil-absorbing layer can adsorb and remove the low-concentration oily organic pollutants such as the surface floating oil in the wastewater again. The adsorbed wastewater mainly enters the third adsorption layer through the through holes, and a small part of the wastewater enters the third adsorption layer through osmosis; then, choose polypropylene-based melt-blown fibers with a smaller water contact angle, that is, weakened lipophilic properties and improved hydrophilic properties, as the adsorption material of the third adsorption layer. At this time, the wastewater mainly contains extremely low-concentration oily organic pollutants in the form of dispersion, emulsification, and dissolution. Improving the hydrophilicity of the adsorption material can further enhance the collision adsorption effect between the pollutants and the oil-absorbing layer, and finally adsorb and remove the "oil-in-water" type of oily organic pollutants. Therefore, the oily wastewater adsorption material provided by the present invention effectively adapts to the hydrophilic and lipophilic properties of the adsorption material required due to the change in the concentration of oily organic pollutants in water by setting adsorption layers with different water contact angles and different hydrophilic and lipophilic properties, and greatly improves the adsorption and removal effect of oily organic pollutants with different concentrations and different states.

[0072] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention.

Claims

1. An oily wastewater adsorption material, comprising two or more adsorption layers stacked in layers; along the thickness direction of the oily wastewater adsorption material, the water contact angle of the oily wastewater adsorption material increases or decreases layer by layer; each adsorption layer is a modified polypropylene fiber layer; and each adsorption layer is provided with staggered through holes.

2. The oily wastewater adsorbent according to claim 1, characterized in that: The thickness of each adsorption layer is independently 1 to 10 mm.

3. The oily wastewater adsorbent according to claim 1, characterized in that: The maximum water contact angle of the adsorption layer is 125° to 145°, and the minimum water contact angle of the adsorption layer is 60° to 85°.

4. The oily wastewater adsorbent according to claim 1, characterized in that: The diameter of the polypropylene fibers in the modified polypropylene fiber layer is 1 to 5 μm.

5. The oily wastewater adsorbent according to claim 1, characterized in that: The oily wastewater adsorption material comprises a first adsorption layer, a second adsorption layer and a third adsorption layer which are stacked in sequence.

6. The oily wastewater adsorbent material according to claim 5, characterized in that: The water contact angle of the first adsorption layer is 125° to 145°, the water contact angle of the second adsorption layer is 90° to 120°, and the water contact angle of the third adsorption layer is 60° to 85°.

7. The oily wastewater adsorbent according to claim 1, characterized in that: The adsorption layers are connected by heating fusion or spot welding.

8. The method for preparing the oily wastewater adsorbent according to any one of claims 1 to 7, comprising the following steps: (1) performing graft modification on polypropylene fiber layers respectively to obtain adsorption layers with different water contact angles; through holes are provided in the adsorption layers with different water contact angles; (2) stacking the adsorption layers with different water contact angles obtained in step (1) in a manner that the water contact angles increase or decrease layer by layer, and after fixed connection, obtaining an oily wastewater adsorption material.

9. The preparation method according to claim 8, characterized in that: The grafting modification method in step (1) includes one or more of solution grafting, suspension grafting, plasma grafting and blending modification.

10. Use of the oily wastewater adsorbent material according to any one of claims 1 to 7 or the oily wastewater adsorbent material prepared by the preparation method according to any one of claims 8 to 9 in treating wastewater containing oily organic pollutants.

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