Preparation method of in-situ reconstruction synergistic photocatalysis self-cleaning lithium ion sieve membrane based on waste ceramic

Abstract

The invention discloses a preparation method of an in-situ reconstruction synergistic photocatalysis self-cleaning lithium ion sieve membrane based on waste ceramics, and relates to the technical field of lithium ion sieve membrane materials and resource recycling. The invention aims to solve the problems of poor stability, high cost and relatively low waste utilization degree due to the fact that a traditional self-cleaning ion sieve mostly adopts nano titanium dioxide as a photocatalyst. The method comprises the following steps: 1, pretreatment of waste ceramic; 2, preparing a lithium ion sieve; 3, preparing nano zinc oxide; and 4, preparing the lithium ion sieve membrane with the self-cleaning function. According to the method, the waste ceramic can be efficiently utilized, a porous structure is formed through chemical impregnation and high-temperature calcination, then the porous structure is lithiated, nano ZnO is loaded to serve as a photocatalyst so as to endow the porous structure with a self-cleaning function, the lithium ion sieve membrane is prepared, waste is turned into wealth, and the production cost is reduced. Meanwhile, the capacity and efficiency of adsorbing and desorbing lithium ions are improved, and the stability and the service life of the adsorbent are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion sieve membrane materials and resource recycling, and particularly relates to a preparation method of an in-situ reconstructed and synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics. Background Art

[0002] Lithium, as an important strategic metal, plays an important role in various fields of modern industry. Therefore, effective lithium extraction has become an important direction in lithium resource production. With the rapid development of industrialization and urbanization, the generation amount of waste has been increasing year by year. How to effectively utilize waste has become the focus of global attention. Porous ceramics have the characteristics of high permeability, high porosity, and high specific surface area, and are currently widely used in fields such as filters, catalyst carriers, building, and bone scaffold materials. At the same time, as an important separation material, ion sieve membranes have broad application prospects in fields such as lithium ion batteries, seawater desalination, and wastewater treatment. In addition, ion sieve membranes with self-cleaning functions can effectively reduce the accumulation of pollutants, improve the service life and performance of the membranes. However, most of the existing ion sieve membrane preparation methods use traditional raw materials, and the utilization degree of waste is relatively low. Moreover, due to the presence of various other elements and impurities in actual brine, in order to reduce the pollution of organic substances or microorganisms, block the adsorption and desorption channels, and endow the ion sieve with self-cleaning functions. Most traditional self-cleaning ion sieves use nano-titanium dioxide (TiO 2 ) as a photocatalyst, which has problems such as poor stability and high cost. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems that most traditional self-cleaning ion sieves use nano-titanium dioxide as a photocatalyst, which has poor stability, high cost, and relatively low utilization degree of waste, and to provide a preparation method of an in-situ reconstructed and synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics.

[0004] The purpose of the present invention is to provide a preparation method of a lithium ion sieve membrane with self-cleaning function based on the reuse of waste ceramics. The method uses waste ceramics as a substrate, converts it into a lithium extraction functional material, forms a porous structure through pickling-lithiation-ion exchange, and uses nano-ZnO to composite with the porous ceramics to form a membrane, so as to achieve the synergistic effect of adsorption-self-cleaning, turn waste into treasure, and reduce the production cost. At the same time, it effectively solves the problems of long operation cycle and discontinuous operation of powdered ion sieves, is more conducive to environmental protection, thereby improving the capacity and efficiency of adsorbing and desorbing lithium ions, and improving the stability and service life of the adsorbent.

[0005] The present invention creatively proposes a method for extracting lithium ions with a lithium ion sieve membrane material with self-cleaning function to achieve high-efficiency adsorption of target ions.

[0006] A preparation method of an in-situ reconstruction collaborative photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics is specifically completed according to the following steps:

[0007] I. Pretreatment of waste ceramics:

[0008] ①. Collect waste ceramics, remove the dirt and impurities on the surface of the waste ceramics, then ultrasonically clean, dry, and finally crush them into powders to obtain ceramic powders;

[0009] ②. Immerse the ceramic powders into a nitric acid solution, heat and stir for a period of time, filter, wash with water until neutral, dry under vacuum, and calcine to obtain porous ceramic powders;

[0010] II. Preparation of lithium ion sieve:

[0011] ①. Mix lithium hydroxide and porous ceramic powders, then add deionized water and polyvinyl alcohol, stir and react for a period of time to obtain a slurry; fully dry the slurry to obtain dry precursor powders;

[0012] ②. Heat the dry precursor powders to 600 °C - 900 °C and calcine for a period of time at 600 °C - 900 °C to obtain a lithiumated ceramic product; immerse the lithiumated ceramic product into hydrochloric acid for a period of time, then filter, wash with water until neutral, and finally dry to obtain lithiumated ceramic powders;

[0013] III. Preparation of nano-zinc oxide:

[0014] ①. Dissolve zinc nitrate in deionized water to obtain a zinc nitrate solution; add polyethylene glycol to the zinc nitrate solution, and dropwise add a NaOH solution under stirring to make the pH value of the system 11, then heat and stir for a period of time to obtain a reaction product;

[0015] ②. Centrifuge the reaction product to obtain a precipitate; use absolute ethanol to centrifuge and wash the precipitate 3 - 5 times, dry, and calcine in an air atmosphere for a period of time to obtain nano-zinc oxide;

[0016] IV. Preparation of a lithium ion sieve membrane with self-cleaning function:

[0017] Mix the lithiumated ceramic powders and nano-zinc oxide evenly, then add silica sol and ball mill for a period of time to obtain a slurry; coat the slurry on a glass substrate, dry for a period of time, heat to 300 °C, pre-calcine at 300 °C for a period of time, then heat to 500 °C, and sinter at 500 °C for a period of time to obtain an in-situ reconstruction collaborative photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics.

[0018] The principle of the present invention:

[0019] 1. The present invention uses waste ceramics as the substrate, and increases its active sites through chemical impregnation and high-temperature calcination. At the same time, a porous structure is formed through the thermally induced pore effect to improve the diffusion and adsorption rates of Li + .

[0020] 2. On the basis of the porous ceramics, the present invention further lithiates them to form lithiated ceramic powder (Li-PCP), providing a porous mass transfer channel and enhancing the specific recognition of Li + .

[0021] 3. The present invention uses nano-ZnO as a photocatalyst, enabling the ion sieve membrane to have a photocatalytic self-cleaning function, which can catalytically decompose organic pollutants, thereby slowing down the problems of the decline in adsorption capacity and service life of the ion sieve membrane during cyclic desorption.

[0022] The preparation method of an in-situ reconstruction and synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics of the present invention has the beneficial effects as follows:

[0023] 1. Using waste ceramics as raw materials and lithiating them realizes the resource utilization of waste materials, turning waste into treasure, avoiding the high cost problem of traditional materials, and at the same time reducing the environmental pollution caused by ceramic landfill;

[0024] 2. Avoid using TiO 2 with poor stability, high cost and dependence on ultraviolet light. Replacing it with ZnO endows the membrane with a self-cleaning function, which can effectively decompose organic pollutants and improve the service life and performance of the membrane;

[0025] 3. ZnO is combined with lithiated ceramic powder (Li-PCP), and through a one-step co-blending and sintering method, a self-cleaning porous ion sieve membrane (LiZn-SCPM) is prepared. The photocatalytic active sites and ion sieve adsorption sites act synergistically to achieve a double breakthrough of "turning waste into treasure + self-cleaning", solving the problem of easy pollution of traditional membranes;

[0026] 4. The lithiated porous ceramic powder can form rich adsorption sites, significantly improving the adsorption capacity of lithium ions. Description of the Drawings

[0027] Figure 1 is the adsorption capacity diagram of the lithium ion sieve membranes prepared by changing the mass ratio of lithium hydroxide and porous ceramic powder in Examples 1 to 3;

[0028] Figure 2 is the adsorption capacity diagram of the lithium ion sieve membranes prepared by changing the mass ratio of lithiated ceramic powder and nano-zinc oxide in Examples 1, 4 and 5;

[0029] Figure 3It is the photocatalytic efficiency diagram of the lithium-ion sieve membranes prepared by changing the mass ratio of the lithiated ceramic powder and nano-zinc oxide in Examples 1, 4, and 5;

[0030] Figure 4 It is the adsorption capacity diagram and photocatalytic degradation efficiency diagram of the lithium-ion sieve membrane prepared in Example 1 after 10 cycles of adsorption and desorption. Specific embodiments

[0031] Specific embodiment 1: This embodiment 1 is a preparation method of a self-cleaning lithium-ion sieve membrane based on in-situ reconstruction of waste ceramics and synergistic photocatalysis, and it is specifically completed according to the following steps:

[0032] I. Pretreatment of waste ceramics:

[0033] ①. Collect waste ceramics, remove the dirt and impurities on the surface of the waste ceramics, then ultrasonically clean, dry, and finally crush them into powder to obtain ceramic powder;

[0034] ②. Immerse the ceramic powder in a nitric acid solution, heat and stir for a period of time, filter, wash with water until neutral, vacuum dry, and calcine to obtain porous ceramic powder;

[0035] II. Preparation of lithium-ion sieve:

[0036] ①. Mix lithium hydroxide and porous ceramic powder, then add deionized water and polyvinyl alcohol, stir and react for a period of time to obtain a slurry; fully dry the slurry to obtain dry precursor powder;

[0037] ②. Heat the dry precursor powder to 600 °C - 900 °C and calcine for a period of time at 600 °C - 900 °C to obtain a lithiated ceramic product; immerse the lithiated ceramic product in hydrochloric acid for a period of time, then filter, wash with water until neutral, and finally dry to obtain lithiated ceramic powder;

[0038] III. Preparation of nano-zinc oxide:

[0039] ①. Dissolve zinc nitrate in deionized water to obtain a zinc nitrate solution; add polyethylene glycol to the zinc nitrate solution, and dropwise add NaOH solution under stirring to make the pH value of the system 11, then heat and stir for a period of time to obtain a reaction product;

[0040] ②. Centrifuge the reaction product to obtain a precipitate; use absolute ethanol to centrifuge and wash the precipitate 3 - 5 times, dry, and calcine in an air atmosphere for a period of time to obtain nano-zinc oxide;

[0041] IV. Preparation of a lithium-ion sieve membrane with self-cleaning function:

[0042] Mix the lithiated ceramic powder and nano-zinc oxide evenly, then add silica sol and ball mill for a period of time to obtain a slurry; coat the slurry on a glass substrate, dry for a period of time, heat up to 300 °C, pre-burn at 300 °C for a period of time, then heat up to 500 °C, and sinter at 500 °C for a period of time to obtain an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics.

[0043] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that: the solvent for ultrasonic cleaning in Step ① is deionized water, and the ultrasonic cleaning time is 20 min to 30 min; the particle size of the ceramic powder in Step ① is 200 mesh to 300 mesh; the ceramic in Step ① is construction ceramic waste, daily-use ceramic waste or industrial ceramic waste. Other steps are the same as those in Specific Embodiment 1.

[0044] Specific Embodiment 3: The difference between this embodiment and one of Specific Embodiments 1 or 2 is that: the concentration of the nitric acid solution in Step ② is 3 mol / L to 4 mol / L; the mass ratio of the ceramic powder to the volume of the nitric acid solution in Step ② is 1 g:(10 mL to 15 mL); the temperature for heating and stirring in Step ② is 60 °C to 70 °C, and the heating and stirring time is 3 h to 4 h. Other steps are the same as those in Specific Embodiment 1 or 2.

[0045] Specific Embodiment 4: The difference between this embodiment and one of Specific Embodiments 1 to 3 is that: the temperature for vacuum drying in Step ② is 80 °C to 100 °C, and the vacuum drying time is 10 h to 12 h; the calcination process in Step ② is: heat up to 800 °C to 850 °C at a heating rate of 5 °C / min to 10 °C / min, and calcine at 800 °C to 850 °C for 2 h to 3 h. Other steps are the same as those in Specific Embodiments 1 to 3.

[0046] Specific Embodiment 5: The difference between this embodiment and one of Specific Embodiments 1 to 4 is that: the mass ratio of lithium hydroxide to porous ceramic powder in Step ② is (3 to 5):1; the mass-volume ratio of lithium hydroxide, polyvinyl alcohol and deionized water in Step ② is (3 g to 5 g):(0.1 g to 0.5 g):(37.5 mL to 125 mL); the stirring reaction speed in Step ② is 100 r / min to 300 r / min, and the stirring reaction time is 30 min to 60 min. Other steps are the same as those in Specific Embodiments 1 to 4.

[0047] Specific Embodiment Six: The difference between this embodiment and any one of Specific Embodiments One to Five is as follows: In step 2②, the heating rate is 5°C / min to 10°C / min; the calcination time is 3h to 6h; in step 2②, the concentration of hydrochloric acid is 2mol / L to 3mol / L; in step 2②, the lithiated ceramic product is immersed in hydrochloric acid for 3h to 4h, then filtered, washed with water until neutral, and finally dried at 60°C to 80°C for 12h to 24h to obtain lithiated ceramic powder. Other steps are the same as those in Specific Embodiments One to Five.

[0048] Specific Embodiment Seven: The difference between this embodiment and any one of Specific Embodiments One to Six is as follows: In step 3①, the concentration of the zinc nitrate solution is 0.1mol / L to 0.2mol / L; the concentration of the NaOH solution in step 3① is 2mol / ; the polyethylene glycol in step 3① is PEG - 6000; the concentration of polyethylene glycol in the system in step 3① is 0.1mol / L; the temperature of heating and stirring in step 3① is 60°C to 70°C, and the heating and stirring time is 2h to 3h. Other steps are the same as those in Specific Embodiments One to Six.

[0049] Specific Embodiment Eight: The difference between this embodiment and any one of Specific Embodiments One to Seven is as follows: In step 3②, the centrifugation time is 10min to 15min, and the centrifugation speed is 5000rpm to 6000rpm; the drying temperature in step 3② is 80°C to 100°C, and the drying time is 6h to 12h; the calcination temperature in step 3② is 500°C to 550°C, and the calcination time is 2h to 3h; the particle size of the nano - zinc oxide in step 3② is 30nm to 50nm. Other steps are the same as those in Specific Embodiments One to Seven.

[0050] Specific Embodiment Nine: The difference between this embodiment and any one of Specific Embodiments One to Eight is as follows: In step 4, the mass ratio of the lithiated ceramic powder to the nano - zinc oxide is (70 - 90):(10 - 30); the silica sol accounts for 5% to 15% of the total mass of the lithiated ceramic powder and the nano - zinc oxide; the model of the silica sol in step 4 is SILICA SOL S - 30; the ball - milling time in step 4 is 6h to 8h; the drying temperature in step 4 is 80°C to 100°C, and the drying time is 2h to 3h. Other steps are the same as those in Specific Embodiments One to Eight.

[0051] Embodiment 10 in detail: The difference between this embodiment and any one of Embodiments 1 to 9 is as follows: In Step 4, the heating rate is 3°C / min to 5°C / min; in Step 4, the pre-burning time at 300°C is 1 h to 2 h; in Step 4, the sintering time at 500°C is 2 h to 3 h; the thickness of the in-situ reconstruction synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics described in Step 4 is 50 μm to 200 μm. Other steps are the same as those in Embodiments 1 to 9.

[0052] The following examples are used to verify the beneficial effects of the present invention:

[0053] Example 1: A preparation method of an in-situ reconstruction synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics is specifically completed according to the following steps:

[0054] I. Pretreatment of waste ceramics:

[0055] ①. Collect waste ceramics, remove the dirt and impurities on the surface of the waste ceramics, then perform ultrasonic cleaning, drying, and finally crush them into powders to obtain ceramic powders;

[0056] In Step ① of Step I, the solvent for ultrasonic cleaning is deionized water, and the ultrasonic cleaning time is 20 min;

[0057] In Step ① of Step I, the particle size of the ceramic powders is 200 mesh to 300 mesh;

[0058] In Step ① of Step I, the ceramics are building ceramic waste;

[0059] ②. Immerse the ceramic powders in a nitric acid solution, heat and stir for a period of time, filter, wash with water until neutral, vacuum dry, and calcine to obtain porous ceramic powders;

[0060] In Step ② of Step I, the concentration of the nitric acid solution is 3 mol / L;

[0061] In Step ② of Step I, the mass ratio of the ceramic powders to the volume of the nitric acid solution is 1 g:10 mL;

[0062] In Step ② of Step I, the heating and stirring temperature is 60°C, and the heating and stirring time is 3 h;

[0063] In Step ② of Step I, the vacuum drying temperature is 80°C, and the vacuum drying time is 12 h;

[0064] In Step ② of Step I, the calcination process is: heating at a heating rate of 5°C / min to 850°C and calcining at 850°C for 2 h;

[0065] II. Preparation of lithium ion sieve:

[0066] ①. Mix lithium hydroxide and porous ceramic powder, then add deionized water and polyvinyl alcohol, stir and react for a period of time to obtain a slurry; fully dry the slurry to obtain dry precursor powder;

[0067] In step two ①, the mass ratio of the lithium hydroxide to the porous ceramic powder is 4:1;

[0068] In step two ①, the mass-volume ratio of the lithium hydroxide, polyvinyl alcohol and deionized water is 4g:0.1g:50mL;

[0069] In step two ①, the stirring speed of the reaction is 250 r / min, and the stirring reaction time is 45 min;

[0070] ②. Heat the dry precursor powder to 800 °C, calcine at 800 °C for a period of time to obtain a lithiumated ceramic product; immerse the lithiumated ceramic product in hydrochloric acid for a period of time, then filter, wash with water until neutral, and finally dry to obtain lithiumated ceramic powder;

[0071] In step two ②, the heating rate is 8 °C / min; the calcination time is 6 h;

[0072] In step two ②, the concentration of the hydrochloric acid is 2 mol / L;

[0073] In step two ②, immerse the lithiumated ceramic product in hydrochloric acid for 3 h, then filter, wash with water until neutral, and finally dry at 80 °C for 12 h to obtain lithiumated ceramic powder (Li-PCP);

[0074] III. Preparation of nano zinc oxide:

[0075] ①. Dissolve zinc nitrate in deionized water to obtain a zinc nitrate solution; add polyethylene glycol to the zinc nitrate solution, and dropwise add NaOH solution under stirring to make the pH value of the system 11, then heat and stir for a period of time to obtain a reaction product;

[0076] In step three ①, the concentration of the zinc nitrate solution is 0.15 mol / L;

[0077] In step three ①, the concentration of the NaOH solution is 2 mol / L;

[0078] In step three ①, the polyethylene glycol is PEG-6000;

[0079] In step three ①, the concentration of polyethylene glycol in the system is 0.1 mol / L;

[0080] In step three ①, the temperature of the heating and stirring is 60 °C, and the heating and stirring time is 2 h;

[0081] ② Centrifuge the reaction product to obtain a precipitate; wash the precipitate with anhydrous ethanol by centrifugation 3 to 5 times, dry it, and calcine it in an air atmosphere for a period of time to obtain nano-zinc oxide;

[0082] In step three ②, the centrifugation time is 10 min and the centrifugation speed is 5000 rpm;

[0083] In step three ②, the drying temperature is 80 °C and the drying time is 8 h;

[0084] In step three ②, the calcination temperature is 500 °C and the calcination time is 2 h;

[0085] In step three ②, the particle size of the nano-zinc oxide is 30 nm to 50 nm;

[0086] IV. Preparation of a self-cleaning functional lithium ion sieve membrane:

[0087] Mix the lithiated ceramic powder (Li-PCP) and nano-zinc oxide (ZnO) evenly, then add silica sol and ball mill for a period of time to obtain a slurry; coat the slurry on a glass substrate, dry for a period of time, heat up to 300 °C, pre-calcine at 300 °C for 1 h, then heat up to 500 °C and sinter at 500 °C for 2 h to obtain an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics (LiZn-SCPM composite membrane);

[0088] In step four, the mass ratio of the lithiated ceramic powder to the nano-zinc oxide is 80:20;

[0089] In step four, the silica sol accounts for 10% of the total mass of the lithiated ceramic powder and the nano-zinc oxide;

[0090] In step four, the model of the silica sol is SILICA SOL S-30, purchased from Shanghai Macklin Biochemical Co., Ltd.;

[0091] In step four, the ball milling time is 6 h;

[0092] In step four, the drying temperature is 80 °C and the drying time is 2 h;

[0093] In step four, the heating rate is 3 °C / min;

[0094] The thickness of the in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics described in step four is 200 μm.

[0095] The lithium ion adsorption capacity of the in-situ reconstructed and synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics prepared in Example 1 is 19.5 mg / g, the degradation rate of methylene blue is 92%, the retention rate of adsorption capacity after 10 cycles is ≥80%, and the selectivity is Li+>Na+>K+>Mg2+.

[0096] Example 2: The difference between this example and Example 1 is that the mass ratio of lithium hydroxide to porous ceramic powder in step 2① is 3:1. Other steps and parameters are the same as those in Example 1.

[0097] Compared with Example 1, due to insufficient lithiation degree and reduced active sites, the lithium ion adsorption capacity of the in-situ reconstructed and synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics prepared in Example 2 is 15.2 mg / g.

[0098] Example 3: The difference between this example and Example 1 is that the mass ratio of lithium hydroxide to porous ceramic powder in step 2① is 5:1. Other steps and parameters are the same as those in Example 1.

[0099] Compared with Example 1, an excessive lithium source will cause partial blockage of pores. The lithium ion adsorption capacity of the in-situ reconstructed and synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics prepared in Example 3 is 20.1 mg / g.

[0100] Example 4: The difference between this example and Example 1 is that the mass ratio of lithiated ceramic powder to nano-zinc oxide in step 4 is 70:30. Other steps and parameters are the same as those in Example 1.

[0101] Compared with Example 1, since the proportion of ZnO increases to 30%, the active sites increase, but to a certain extent, it causes partial blockage of pores. The lithium ion adsorption capacity of the in-situ reconstructed and synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics prepared in Example 4 is 16.3 mg / g, and the degradation rate is 95%.

[0102] Example 5: The difference between this example and Example 1 is that the mass ratio of lithiated ceramic powder to nano-zinc oxide in step 4 is 90:10. Other steps and parameters are the same as those in Example 1.

[0103] Compared with Example 1, since the proportion of ZnO decreases to 10%, the porosity increases, but the photocatalytic efficiency decreases significantly. The lithium ion adsorption capacity of the in-situ reconstructed and synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics prepared in Example 5 is 19.0 mg / g, and the degradation rate is 85%.

[0104] Figure 1 It is the adsorption capacity diagram of the lithium ion sieve membrane prepared by changing the mass ratio of lithium hydroxide to porous ceramic powder in Examples 1 to 3;

[0105] From Figure 1 it can be seen that in order to explore the influence of lithium source on the lithium ion adsorption capacity, it is necessary to change the ratio of lithium source (lithium hydroxide) to porous ceramic powder (PCP). When Li:PCP is 3:1, due to insufficient lithiation degree and reduced active sites, the lithium ion adsorption amount is 15.2 mg / g; when Li:PCP is 5:1, the excessive lithium source will cause partial blockage of pores, and the lithium ion adsorption amount is 20.1 mg / g. Generally speaking, when Li:PCP is 4:1, the performance is better.

[0106] Figure 2 It is the adsorption capacity diagram of the lithium ion sieve membrane prepared by changing the mass ratio of lithiated ceramic powder and nano-zinc oxide in Examples 1, 4, and 5;

[0107] From Figure 2 it can be seen that in order to optimize the balance of photocatalysis on adsorption performance, it is necessary to change the different mass ratios of Li-PCP and ZnO. When Li-PCP and ZnO are 70:30, the proportion of ZnO increases to 30%, so the active sites increase, but to a certain extent, it causes partial blockage of pores, and the adsorption capacity is 16.3 mg / g; when Li-PCP and ZnO are 90:10, since the proportion of ZnO drops to 10%, the porosity increases, and the lithium ion adsorption amount is 19.0 mg / g. Generally speaking, when Li-PCP and ZnO are 80:20, the performance is better.

[0108] The LiZn-SCPM composite membrane (1 cm × 1 cm) was immersed in 100 mL of methylene blue solution with an initial concentration of 10 mg / L, and dark adsorption was carried out for 30 minutes until equilibrium. The performance of the membrane for photocatalytic degradation of organic pollutant methylene blue (MB) in water was tested with a xenon lamp as the light source. 3 mL of the solution was sampled every 60 minutes, and suspended particles were removed by centrifugation. The absorbance of the supernatant at 664 nm was measured by UV-Vis, and the remaining concentration was calculated through the standard curve, and the degradation rate at each time point was recorded.

[0109] Figure 3 It is the photocatalytic efficiency diagram of the lithium ion sieve membrane prepared by changing the mass ratio of lithiated ceramic powder and nano-zinc oxide in Examples 1, 4, and 5;

[0110] From Figure 3 it can be seen that when Li-PCP and ZnO are 70:30, the photocatalytic activity is insufficient, and the photocatalytic efficiency is 85%; when Li-PCP and ZnO are 90:10, the photocatalytic activity is the highest, but excessive ZnO may block pores and the adsorption performance is weak, and the photocatalytic efficiency is 95%; generally speaking, when Li-PCP and ZnO are 80:20, the degradation rate and adsorption performance are balanced, and the comprehensive efficiency is the best.

[0111] To investigate the cyclic stability of the membrane, the membrane was immersed in simulated salt lake brine (Li+ concentration 100 mg / L, pH = 7), adsorbed for 12 hours at 25 °C, and the adsorption capacity was measured. Then the membrane was immersed in deionized water and stirred at 40 °C for 2 hours to release Li+, and the adsorption capacity was measured again. Adsorption capacity retention rate = Li+ adsorption capacity / initial adsorption capacity × 100%;

[0112] Figure 4 are the adsorption capacity diagram and photocatalytic degradation efficiency diagram of the lithium ion sieve membrane prepared in Example 1 after 10 cycles of adsorption and desorption;

[0113] From Figure 4 it can be seen that the initial adsorption capacity is 19.5 mg / g, the retention rate after 10 cycles is 83.1%, and the degradation rate is 74%. It proves that the LiZn-SCPM membrane has good stability.

Claims

1. A method for preparing an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics, characterized in that The preparation method is specifically completed according to the following steps:

1. Pretreatment of waste ceramics: ① Collect waste ceramics, remove dirt and impurities on the surface of the waste ceramics, then ultrasonically clean, dry, and finally crush into powder to obtain ceramic powder; ②, immerse the ceramic powder in a nitric acid solution, heat and stir for a period of time, filter, wash with water until neutral, vacuum dry, and calcine to obtain a porous ceramic powder; 2. Preparation of lithium ion sieve: ①, lithium hydroxide and porous ceramic powder are mixed, deionized water and polyvinyl alcohol are added, and the mixture is stirred for a period of time to obtain a slurry; the slurry is fully dried to obtain a dry precursor powder; ②, heating the dried precursor powder to 600°C to 900°C, calcining at 600°C to 900°C for a period of time to obtain a lithiated ceramic product; immersing the lithiated ceramic product in hydrochloric acid for a period of time, filtering, washing with water to neutrality, and finally drying to obtain a lithiated ceramic powder; 3. Preparation of Nano Zinc Oxide: ①, dissolving zinc nitrate in deionized water to obtain a zinc nitrate solution; adding polyethylene glycol to the zinc nitrate solution, adding dropwise a NaOH solution under stirring conditions to adjust the pH value of the system to 11, and then heating and stirring for a period of time to obtain a reaction product; ②, centrifuge the reaction product to obtain a precipitate; use anhydrous ethanol to centrifuge and wash the precipitate 3 to 5 times, dry it, and calcine it in an air atmosphere for a period of time to obtain nano zinc oxide; 4. Preparation of self-cleaning lithium ion sieve membrane: The lithiated ceramic powder and nano zinc oxide are mixed evenly, and then silica sol is added and ball-milled for a period of time to obtain a slurry; the slurry is coated on a glass substrate, dried for a period of time, heated to 300°C, pre-fired at 300°C for a period of time, then heated to 500°C, and sintered at 500°C for a period of time to obtain an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics.

2. The method for preparing an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics according to claim 1, characterized in that The solvent for ultrasonic cleaning described in step 1① is deionized water, and the time for ultrasonic cleaning is 20min to 30min; the particle size of the ceramic powder described in step 1① is 200 mesh to 300 mesh; the ceramic described in step 1① is building ceramic waste, daily ceramic waste or industrial ceramic waste.

3. The method for preparing an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics according to claim 1, characterized in that The concentration of the nitric acid solution described in step 1② is 3mol / L~4mol / L; the volume ratio of the mass of the ceramic powder described in step 1② to the nitric acid solution is 1g:(10mL~15mL); the temperature of heating and stirring described in step 1② is 60℃~70℃, and the time of heating and stirring is 3h~4h.

4. The method for preparing an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics according to claim 1, characterized in that The vacuum drying temperature described in step 1② is 80℃~100℃, and the vacuum drying time is 10h~12h; the calcination process described in step 1② is: heating to 800℃~850℃ at a heating rate of 5℃ / min~10℃ / min, and calcining at 800℃~850℃ for 2h~3h.

5. The method for preparing an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics according to claim 1, characterized in that The mass ratio of lithium hydroxide and porous ceramic powder described in step 2① is (3-5):1; the mass volume ratio of lithium hydroxide, polyvinyl alcohol and deionized water described in step 2① is (3g-5g):(0.1g-0.5g):(37.5mL-125mL); the stirring reaction speed described in step 2① is 100r / min-300r / min, and the stirring reaction time is 30min-60min.

6. The method for preparing an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics according to claim 1, characterized in that The heating rate described in step 2② is 5℃ / min~10℃ / min; the calcination time is 3h~6h; the concentration of hydrochloric acid described in step 2② is 2mol / L~3mol / L; in step 2②, the lithiated ceramic product is immersed in hydrochloric acid for 3h~4h, then filtered, washed with water to neutrality, and finally dried at 60℃~80℃ for 12h~24h to obtain lithiated ceramic powder.

7. The method for preparing an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics according to claim 1, characterized in that The concentration of the zinc nitrate solution described in step 3① is 0.1mol / L~0.2mol / L; the concentration of the NaOH solution described in step 3① is 2mol / ; the polyethylene glycol described in step 3① is PEG-6000; the concentration of polyethylene glycol in the system described in step 3① is 0.1mol / L; the temperature of heating and stirring described in step 3① is 60℃~70℃, and the time of heating and stirring is 2h~3h.

8. The method for preparing an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics according to claim 1, characterized in that The centrifugation time described in step 3② is 10min~15min, and the centrifugation speed is 5000rpm~6000rpm; the drying temperature described in step 3② is 80℃~100℃, and the drying time is 6h~12h; the calcination temperature described in step 3② is 500℃~550℃, and the calcination time is 2h~3h; the particle size of the nano zinc oxide described in step 3② is 30nm~50nm.

9. The method for preparing an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics according to claim 1, characterized in that The mass ratio of the lithiated ceramic powder and the nano zinc oxide described in step 4 is (70-90):(10-30); the silica sol described in step 4 accounts for 5%-15% of the total mass of the lithiated ceramic powder and the nano zinc oxide; the model of the silica sol described in step 4 is SILICA SOL S-30; the ball milling time described in step 4 is 6h-8h; the drying temperature described in step 4 is 80°C-100°C, and the drying time is 2h-3h.

10. The method for preparing an in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics according to claim 1, characterized in that The heating rate described in step 4 is 3°C / min to 5°C / min; the pre-firing time at 300°C in step 4 is 1h to 2h; the sintering time at 500°C in step 4 is 2h to 3h; the thickness of the in-situ reconstructed synergistic photocatalytic self-cleaning lithium ion sieve membrane based on waste ceramics described in step 4 is 50μm to 200μm.

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