Filter materials, methods of making and using the same

Abstract

This invention provides a filter material, its preparation method, and its application. The filter material is prepared by in-situ growth of nickel-titanium layered double hydroxide material NiTi-LDH on the surface of a foamed titanium substrate using a one-step hydrothermal method. The filter material NiTi-LDH / TF has superhydrophilic and underwater superoleophobic properties. When filtering oil-in-water emulsions, it can be combined with in-situ aeration using an external electric field to prevent oil droplets from adhering to or passing through the filter material, significantly enhancing the emulsion separation and antifouling performance of the filter material, and exhibiting extremely strong cycle durability.

Description

Technical Field

[0001] This invention relates to the field of surface modification technology for metal foam materials, specifically to a filter material, its preparation method, and its application. Background Technology

[0002] For decades, the treatment of oily wastewater has been a persistent environmental problem, as it originates widely from various industrial sectors, including oil, natural gas, and food, posing potential risks to ecosystems and human health. In particular, the frequent occurrence of marine oil spills has heightened public awareness of the urgency of addressing the issue of oily wastewater in the marine environment.

[0003] Traditional oily wastewater treatment technologies, such as flotation, skimming, biodegradation, and chemical reactions, suffer from secondary pollution, high energy consumption, and low efficiency. Therefore, an environmentally friendly and efficient alternative technology is urgently needed. Compared to traditional oil-water mixtures, treating surfactant-stabilized oil-in-water emulsions presents a greater challenge because oil droplets are smaller, typically less than 20 μm, and the stability of surfactants on these droplets makes the emulsion less prone to "breakdown."

[0004] Gravity-driven membrane separation technology, as a physical separation process, offers superior performance in terms of environmental protection, energy conservation, and sustainable development compared to other methods. However, membrane fouling hinders its development. Although studies have demonstrated the effectiveness of membrane separation technology in separating oil-in-water emulsions, this method is limited by external driving force and short lifespan, preventing large-scale industrial application. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the main objective of this invention is to provide a filter material, its preparation method, and its application. This filter material is prepared by in-situ growth of nickel-titanium layered double hydroxide material (NiTi-LDH) on the surface of a foamed titanium substrate using a one-step hydrothermal method. The NiTi-LDH / TF filter material has superhydrophilic and underwater superoleophobic properties. When filtering oil-in-water emulsions, it can be combined with in-situ aeration using an external electric field to prevent oil droplets from adhering to or passing through the filter material, significantly enhancing the emulsion separation and antifouling performance of the filter material, and exhibiting extremely strong cycle durability.

[0006] To achieve the above objectives, according to a first aspect of the present invention, a filter material is provided.

[0007] The filter material includes titanium foam and a nickel-titanium layered double hydroxide material grown in situ on at least a portion of the surface of the titanium foam.

[0008] Furthermore, the nickel-titanium layered double hydroxide material forms a three-dimensional flower-like structure and / or sheet-like structure on the surface of the nickel foam.

[0009] Furthermore, the pore size of the foamed titanium is less than or equal to 5 μm and greater than 0.

[0010] To achieve the above objectives, according to a second aspect of the present invention, a method for preparing a filter material is provided.

[0011] The preparation method of this filter material includes the following steps:

[0012] Pretreatment of foamed titanium;

[0013] Prepare a reaction solution containing nickel ions, and the reaction solution is alkaline;

[0014] The pretreated foamed titanium is subjected to a hydrothermal reaction with the reaction solution to obtain the filter material.

[0015] Furthermore, the pretreatment process includes: firstly, ultrasonically cleaning the foamed titanium with acetone and hydrochloric acid solutions in sequence, then rinsing with deionized water, and finally performing a first drying treatment.

[0016] Furthermore, the foamed titanium is ultrasonically cleaned in the acetone and hydrochloric acid solutions for 10-15 minutes each;

[0017] Preferably, the temperature of the first drying treatment is 60-65°C.

[0018] Furthermore, the reaction solution is an aqueous solution comprising nickel ions, urea, and ammonium fluoride;

[0019] Preferably, the reaction solution is an aqueous solution of nickel sulfate, urea, and ammonium fluoride;

[0020] Preferably, the mass percentages of the nickel ions, the urea, and the ammonium fluoride are 20-30%, 50-60%, and 10-25%, respectively.

[0021] Furthermore, the temperature of the hydrothermal reaction is 120–130°C, preferably 130°C; the reaction time is 3–4 hours, preferably 3 hours.

[0022] Furthermore, it also includes: washing and second drying the obtained filter material;

[0023] Preferably, the washing is performed by rinsing with deionized water;

[0024] Preferably, the temperature of the second drying treatment is 60-65°C.

[0025] To achieve the above objectives, according to a third aspect of the present invention, an application of a filter material is provided.

[0026] The application of the filter material provided in the first aspect of the present invention or the filter material prepared by the method provided in the second aspect of the present invention in the treatment of oily wastewater;

[0027] Preferably, the oily wastewater is an oil-in-water emulsion and / or an oil-water mixture.

[0028] Advantages of this invention:

[0029] 1. This invention uses a one-step hydrothermal method to grow nickel-titanium layered double hydroxide material (NiTi-LDH) in situ on the surface of a foamed titanium substrate to prepare filter material NiTi-LDH / TF. The surface roughness of the material is improved by the hydrophilic groups in LDH, so that the filter material NiTi-LDH / TF has superhydrophilic and underwater superoleophobic properties.

[0030] 2. In this invention, an external electric field is used to record the separation performance of the filter material for oil-in-water emulsions. The results show that after filtration for 30 minutes under electric field conditions, a separation efficiency of over 99% can be achieved for different types of oil-in-water emulsions, and the performance does not decrease in hundreds of cycles.

[0031] 3. The filter material in this invention is suitable for separating light oil-type oil-in-water emulsions and various typical oil-water mixtures, and the separation effect and anti-fouling performance are improved by an external electric field.

[0032] 4. The preparation method in this invention has the advantages of simple process, low equipment requirements, low cost, and easy large-scale industrial application. Attached Figure Description

[0033] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings:

[0034] Figure 1 A schematic diagram of the experimental method for preparing the filter material NiTi-LDH / TF in the embodiments provided by the present invention;

[0035] Figure 2 Scanning electron microscope (SEM) images of the NiTi-LDH / TF filter material prepared in the embodiments provided by the present invention; wherein, Figure 2 (a) and Figure 2 (b) are scanning electron microscope images at different magnifications;

[0036] Figure 3 The separation performance and flux of the NiTi-LDH / TF filter material prepared in the embodiments of the present invention when separating petroleum ether emulsions are shown in the figure; wherein, Figure 3(a) shows the separation performance and flux under conditions without an applied electric field; Figure 3 (b) is a graph showing the rejection rate versus flux under the applied electric field condition;

[0037] Figure 4 The separation performance and flux of the NiTi-LDH / TF filter material prepared in the embodiments of the present invention when separating edible oil emulsions are shown in the figure; wherein, Figure 4 (a) shows the separation performance and flux under conditions without an applied electric field; Figure 4 (b) is a graph showing the separation performance and flux under the applied electric field condition;

[0038] Figure 5 The separation performance and flux of the NiTi-LDH / TF filter material prepared in the embodiments of the present invention when separating n-hexane emulsion are shown in the figure; wherein, Figure 5 (a) shows the separation performance and flux under conditions without an applied electric field; Figure 5 (b) is a graph showing the separation performance and flux under the applied electric field condition;

[0039] Figure 6 The separation performance and flux diagram of the NiTi-LDH / TF filter material prepared in the embodiments of the present invention when separating gasoline emulsions; wherein, Figure 6 (a) shows the separation performance and flux under conditions without an applied electric field; Figure 6 (b) is a graph showing the separation performance and flux under the applied electric field condition;

[0040] Figure 7 The antifouling performance diagram and emulsion "demulsification" diagram of the NiTi-LDH / TF filter material prepared in the embodiments provided by the present invention are shown; wherein, Figure 7 (a) is a diagram showing the antifouling performance of the filter material NiTi-LDH / TF; Figure 7 (b) A graph showing the emulsion breaking process during a 30-minute filtration period;

[0041] Figure 8 Cyclic durability test diagram of the filter material NiTi-LDH / TF prepared in the embodiments provided by the present invention. Detailed Implementation

[0042] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0043] To overcome the shortcomings of existing technologies and reduce membrane fouling, this invention provides a new approach that utilizes the conductivity of membranes to effectively combine in-situ aeration and electroflotation technologies with membrane separation processes. At the same time, the substrate titanium foam has controllable pore size and good overall conductivity, which greatly overcomes the problem of limited service life of membranes prepared by current technologies through grafting modification or chemical plating.

[0044] This invention provides a novel strategy that combines advanced filter materials with electroflotation, utilizing in-situ aeration under an electric field to improve the separation performance and antifouling properties of foam metal filter materials, thus opening up new avenues for oil-water emulsion separation.

[0045] In a first aspect, the present invention provides a filter material.

[0046] The filter material in this invention includes titanium foam and nickel-titanium layered double hydroxide material (NiTi-LDH) grown in situ on at least a portion of the surface of the titanium foam.

[0047] Among them, nickel-titanium layered double hydroxide material forms a three-dimensional flower-like structure and / or sheet-like structure on the surface of nickel foam.

[0048] The filter material in this invention is a foamed titanium substrate coated with a nickel-titanium layered double hydroxide material NiTi-LDH, and the oil-in-water emulsion is separated by an applied electric field.

[0049] In the embodiments of the present invention, the pore size of the foamed titanium is ≤5μm and the pore size is controllable, and it has excellent electrical conductivity.

[0050] In this invention, foamed titanium is used as the substrate material, which can extend the service life of the membrane while maintaining high separation efficiency.

[0051] It should be noted that the pore size of the foamed titanium is greater than 0 to achieve better filtration.

[0052] In a second aspect, the present invention provides a method for preparing a filter material to obtain the filter material described in the first aspect of the present invention.

[0053] The preparation method of the filter material in this invention is specifically carried out according to the following steps.

[0054] (1) Pre-treat the foamed titanium to obtain clean foamed titanium.

[0055] The pretreatment of foamed titanium is carried out according to the following steps: the foamed titanium is ultrasonically cleaned with acetone and hydrochloric acid solutions respectively to remove fat-soluble impurities and oxide layers on the surface of the foamed titanium; then the foamed titanium is repeatedly washed with deionized water to remove excess cleaning solution; and then the foamed titanium after cleaning is subjected to a first drying treatment.

[0056] In an embodiment of the present invention, the foamed titanium is ultrasonically cleaned in acetone for 10 to 15 minutes to remove fat-soluble impurities from the surface of the foamed titanium.

[0057] For example, the ultrasonic cleaning time of foamed titanium in acetone is 10 min, 11 min, 12 min, 13 min, 14 min, and 15 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0058] In an embodiment of the present invention, the foamed titanium is ultrasonically cleaned in hydrochloric acid solution for 10 to 15 minutes to remove the oxide layer on the surface of the foamed titanium.

[0059] For example, the ultrasonic cleaning time of foamed titanium in hydrochloric acid solution is 10 min, 11 min, 12 min, 13 min, 14 min, and 15 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0060] In one embodiment of the present invention, the concentration of the hydrochloric acid solution is 3 mol / L.

[0061] Of course, you can also choose a hydrochloric acid solution of appropriate concentration according to actual needs for effective cleaning.

[0062] It should be noted that, in order to ensure efficient cleaning, the foamed titanium after ultrasonic cleaning with acetone is rinsed with deionized water before ultrasonic cleaning with hydrochloric acid solution to remove residual acetone from the surface of the foamed titanium.

[0063] In an embodiment of the present invention, the foamed titanium, after being ultrasonically cleaned with acetone and hydrochloric acid, is repeatedly washed with deionized water to remove residual cleaning solution, and then placed in an oven for drying.

[0064] It should be noted that deionized water can be used for ultrasonic cleaning to achieve better cleaning results.

[0065] In an embodiment of the present invention, the temperature of the first drying process is 60-65°C, for example, drying can be carried out in an oven at 60°C.

[0066] (2) Prepare a reaction solution containing nickel ions, and the reaction solution is alkaline.

[0067] In an embodiment of the present invention, the reaction solution is an aqueous solution comprising nickel ions, urea and ammonium fluoride.

[0068] In an embodiment of the present invention, the reaction solution is an aqueous solution of nickel sulfate, urea and ammonium fluoride.

[0069] Among them, nickel sulfate can be nickel sulfate hexahydrate.

[0070] In embodiments of the present invention, the mass percentages of nickel ions, urea, and ammonium fluoride are 20-30%, 50-60%, and 10-25%, respectively.

[0071] In one embodiment of the present invention, the mass percentages of nickel ions, urea, and ammonium fluoride are 30%, 60%, and 10%, respectively.

[0072] In some embodiments of the present invention, the amounts of each substance added to the reaction solution are as follows:

[0073] 0.3–0.4 g nickel sulfate hexahydrate (NiSO4·6H2O), 0.6–0.8 g urea (CH4N2O), 0.1 g ammonium fluoride (NH4F), and 36 mL deionized water.

[0074] In some embodiments of the present invention, the amounts of each substance added to the reaction solution are as follows:

[0075] 0.33g NiSO4·6H2O, 0.7g CH4N2O, 0.1g NH4F and 36mL deionized water.

[0076] (3) The pretreated clean foam titanium and alkaline reaction solution are transferred to a stainless steel reactor for hydrothermal reaction to obtain filter material.

[0077] In embodiments of the present invention, the temperature of the hydrothermal reaction is 120–130°C, for example, 130°C; and the reaction time is 3–4 hours, for example, 3 hours.

[0078] In some embodiments of the present invention, the hydrothermal reaction temperature is 130°C and the reaction time is 3 hours.

[0079] (4) The obtained filter material is washed and then dried.

[0080] The prepared filter material needs to be washed with deionized water to remove excess hydrothermal reaction solution; then the washed filter material is dried.

[0081] In an embodiment of the present invention, the temperature of the second drying process is 60-65°C, for example, drying can be carried out in an oven at a temperature of 60°C.

[0082] It is worth mentioning that the first and second drying processes in this invention can be carried out under a protective atmosphere, such as nitrogen, to prevent oxidation.

[0083] The filter material NiTi-LDH / TF prepared by hydrothermal method in this invention has the characteristics of good durability, high separation efficiency and low energy consumption.

[0084] Under a low-voltage electric field of 5V, the NiTi-LDH / TF filter material achieved a separation efficiency of over 99% within 30 minutes, demonstrating excellent emulsion separation capabilities.

[0085] Meanwhile, in-situ aeration under electric field conditions has good anti-pollution performance.

[0086] It is worth noting that after 100 cycles of separation testing, the separation performance of the NiTi-LDH / TF filter material did not decrease significantly, which highlights the great potential of the NiTi-LDH / TF filter material in practical applications.

[0087] A third aspect of the present invention provides an application of a filter material in the treatment of oily wastewater.

[0088] The filter material is either the filter material provided in the first aspect of the present invention or the filter material prepared by the method provided in the second aspect of the present invention.

[0089] In embodiments of the present invention, the oily wastewater is an oil-in-water emulsion and / or an oil-water mixture.

[0090] The following detailed description of the filter material, its preparation method, and its application in this invention will be provided through specific embodiments.

[0091] Example 1:

[0092] Preparation process as per Figure 1 As shown.

[0093] First, the cut titanium foam sheets (27mm × 27mm × 1mm, pore size ≤ 5μm and > 0) were immersed in 50mL of 3mol / L hydrochloric acid solution and sonicated for 15min to remove the surface oxide layer. Next, they were ultrasonically cleaned with 30mL of acetone for 10min to remove surface lipid impurities. Then, they were rinsed with deionized water and ultrasonically treated again for 10min to remove excess acetone. Finally, the cleaned titanium foam was dried in a 60℃ oven for later use.

[0094] Next, weigh 0.33g NiSO4·6H2O, 0.7g CH4N2O, and 0.1g NH4F and add them to 36mL of deionized water. The mixture is then ultrasonically stirred in a beaker to obtain a homogeneous reaction solution.

[0095] Subsequently, the homogeneous reaction solution was transferred together with the previously prepared foamed titanium into a 50 mL stainless steel reactor and reacted in an oven at 130 °C for 3 h to obtain the filter material NiTi-LDH / TF.

[0096] Finally, the prepared filter material NiTi-LDH / TF was washed with deionized water to remove excess reaction solution, and then dried in an oven at 60°C.

[0097] In this invention, the prepared filter material NiTi-LDH / TF was subjected to SEM testing to examine the morphological changes of the foamed titanium before and after in-situ growth of the nickel-titanium layered double hydroxide material NiTi-LDH. The results are as follows: Figure 2 As shown.

[0098] Figure 2 The results show that the modified titanium foam surface is covered with well-defined lamellar NiTi-LDH structures and clustered flower-like NiTi-LDH structures, proving that NiTi-LDH has been successfully grown on the surface of titanium foam.

[0099] In this invention, in order to achieve filtration of the filter material NiTi-LDH / TF under a DC electric field, graphite is used as the anode and the filter material NiTi-LDH / TF is used as the cathode protection electrode.

[0100] To improve the conductivity of the previously prepared oil-in-water emulsion, 2 g / L of sodium sulfate was added. Compared with other inventions in the same field, this invention highlights the strong electrochemical capabilities of the NiTi-LDH / TF filter material by significantly reducing the amount of conductive agent and the DC electric field voltage. This promotes green economic practices.

[0101] The graphite electrode was located at the top of the filtration device, and the positive and negative terminals of the DC power supply were connected to the graphite electrode and the filter material NiTi-LDH / TF, respectively. The oil-in-water emulsion was poured into the top of the filtration device, and samples were collected every 3 minutes during the filtration process, with a total filtration time of 30 minutes. The entire filtration process was repeated 5 times, and then the average value and error bars were calculated.

[0102] like Figures 3-6 As shown, for petroleum ether emulsions, edible oil emulsions, n-hexane emulsions, and gasoline emulsions, the separation performance steadily increases with increasing electrolysis time. Ultimately, at 30 minutes, a separation performance of over 99% can be achieved for all different types of oil-in-water emulsions.

[0103] In this invention, the antifouling properties of the NiTi-LDH / TF filter material before and after energization were tested, and the results are as follows: Figure 7 As shown.

[0104] Depend on Figure 7 (a) It can be seen that the filter material NiTi-LDH / TF under electric field conditions has no residual oil droplets on its surface after filtration for 30 minutes.

[0105] In this invention, real-world photographs of the gradual demulsification of the oil-in-water emulsion within a 30-minute filtration period were also recorded, such as... Figure 7 As shown in (b).

[0106] The durability of filter materials is one of the criteria for industrial-scale promotion.

[0107] In this invention, the NiTi-LDH / TF filter material underwent hundreds of manual separation cycle tests, and the results are as follows: Figure 8 As shown.

[0108] Depend on Figure 8 It can be seen that the separation performance of the filter material NiTi-LDH / TF did not decrease during 100 separation cycles, demonstrating the excellent durability of the modification method in this invention.

[0109] This invention modifies foamed titanium, enabling the modified foamed titanium to prevent oil droplets from adhering to or passing through the filter material when filtering oil-in-water emulsions by combining with in-situ aeration under an external electric field. This significantly enhances the emulsion separation and antifouling performance of the filter material and provides excellent cycle durability.

[0110] This method is simple to operate, low in cost, and easy to implement in industrial applications, making it of great significance in the application of oily wastewater treatment.

[0111] The filter material NiTi-LDH / TF and its preparation method in this invention are of great significance for practical application and promotion.

[0112] It should be noted that the term "comprising" and any variations thereof in the specification and claims of this invention are intended to cover non-exclusive inclusion, for example, including a series of components that are not necessarily limited to those explicitly listed, but may include other components that are not explicitly listed or that are inherent to the component.

[0113] In this invention, the terms "upper," "lower," "bottom," "top," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0114] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0115] Furthermore, the descriptions of "first," "second," etc., involved in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0116] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0117] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a filter material, characterized in that, The filter material includes titanium foam and nickel-titanium layered double hydroxide material grown in situ on at least a portion of the surface of the titanium foam, wherein the nickel-titanium layered double hydroxide material forms a three-dimensional flower-like structure and a sheet-like structure on the surface of the titanium foam; the pore size of the titanium foam is less than or equal to 5 μm and greater than 0. The preparation method includes the following steps: Pretreatment of foamed titanium; Prepare a reaction solution containing nickel ions, wherein the reaction solution is alkaline; the reaction solution is an aqueous solution comprising nickel ions, urea, and ammonium fluoride; The pretreated foamed titanium is subjected to a hydrothermal reaction with the reaction solution to obtain the filter material; the temperature of the hydrothermal reaction is 120~130℃ and the reaction time is 3~4h.

2. The method for preparing the filter material as described in claim 1, characterized in that, The pretreatment process includes: firstly, ultrasonically cleaning the foamed titanium with acetone and hydrochloric acid solutions in sequence, then rinsing with deionized water, and finally performing a first drying process.

3. The method for preparing the filter material as described in claim 2, characterized in that, The foamed titanium was ultrasonically cleaned in acetone and hydrochloric acid solutions for 10-15 minutes each.

4. The method for preparing the filter material as described in claim 2, characterized in that, The temperature of the first drying process is 60~65℃.

5. The method for preparing the filter material as described in claim 1, characterized in that, The reaction solution is an aqueous solution of nickel sulfate, urea, and ammonium fluoride.

6. The method for preparing the filter material according to claim 1, characterized in that, Also includes: The obtained filter material is then washed and subjected to a second drying process.

7. The method for preparing the filter material as described in claim 6, characterized in that, The washing process involves rinsing with deionized water.

8. The method for preparing the filter material as described in claim 6, characterized in that, The temperature for the second drying process is 60~65℃.

9. The application of a filter material prepared by the method according to any one of claims 1-8 in the treatment of oily wastewater.

10. The application as described in claim 9, characterized in that, The oily wastewater is an oil-in-water emulsion.

Images