Biochar nano lanthanum material capable of synchronously removing organic phosphorus and inorganic phosphorus as well as synthesis method and application of biochar nano lanthanum material

Abstract

The invention discloses a charcoal nano lanthanum material capable of synchronously removing organic phosphorus and inorganic phosphorus, and belongs to the field of environmental functional materials. The adsorbent comprises biochar and nano lanthanum loaded on the biochar, wherein the biochar is bamboo biochar; the nano lanthanum is in a La (OH) 3 form, the particle size of the nano lanthanum is 1-250nm, and the loading capacity of the nano lanthanum is 3-20wt%; the pore diameter of the biochar nano lanthanum material is 1-30nm, and the specific surface area is 100-250m < 2 > / g. Compared with a biochar-loaded nano lanthanum composite material in the prior art, the composite material has the inorganic phosphorus adsorption performance and also has the organic phosphorus adsorption effect, and inorganic phosphorus and organic phosphorus can be synchronously removed. According to the charcoal nano lanthanum material, organic phosphorus is adsorbed and removed by regulating and controlling the defect form of lanthanum, especially organic phosphonate can be hydrolyzed and removed, meanwhile, large pore channels of bamboo charcoal are beneficial to diffusion of macromolecular organic phosphorus to action sites of lanthanum, and the adsorption and hydrolysis effects of lanthanum on the organic phosphorus are further enhanced.

Description

Technical Field

[0001] The present invention belongs to the field of environmental functional materials, and more specifically, relates to a biochar nano-lanthanum material for synchronously removing organic phosphorus and inorganic phosphorus, its synthesis method and application. Background Art

[0002] At present, water eutrophication is a severe worldwide environmental problem, and the excessive phosphorus is the key point of this problem. Reducing the exogenous phosphorus input is an important means to curb the eutrophication of lakes and reservoirs. The exogenous phosphorus control technologies include coagulation sedimentation method, adsorption method, biological treatment method and membrane treatment method. Among them, the adsorption method has received wide attention due to its simple operation, low cost and high selectivity.

[0003] Phosphorus is divided into inorganic phosphorus and organic phosphorus. Among them, inorganic orthophosphate is the easiest to be removed and is the main target of current research. Lanthanum has a strong affinity for phosphate, and still shows high-efficiency removal ability for phosphate even at trace levels. The specific adsorption of lanthanum to phosphorus can generate lanthanum-phosphate complexes. The pKsp of lanthanum phosphate in aqueous solution is 26.15, which is much lower than that of other metal phosphates. Moreover, as a rare earth element, lanthanum has a high abundance in soil and is environmentally friendly. As a strategic resource, China is rich in rare earth deposits, laying a solid foundation for its industrial application.

[0004] However, organic phosphorus, especially phosphonate esters, not only has high toxicity itself, but also can be converted into inorganic orthophosphate, which will also cause a major risk of eutrophication. Traditional methods often only focus on the removal of inorganic phosphorus such as orthophosphate, and pay less attention to organic phosphorus. This results in that traditional methods cannot effectively remove organic phosphorus when controlling the exogenous phosphorus input, leaving a large number of inorganic phosphorus conversion sources and unable to fundamentally solve the problem of excessive phosphorus. Summary of the Invention

[0005] 1. Problems to be Solved

[0006] Aiming at the technical problem in the prior art that only one-sidedly focuses on the removal of inorganic phosphorus such as orthophosphate, leaving organic phosphorus that can be converted into inorganic phosphorus such as phosphate, and unable to fundamentally solve the problem of excessive phosphorus, the present invention provides a biochar nano-lanthanum material for effectively synchronously removing organic phosphorus and inorganic phosphorus and its synthesis method. Using biochar as a carrier and loading lanthanum nanoparticles, lanthanum with a defective weak crystal structure can be formed, enhancing its degradation performance for organic phosphorus, synchronously realizing the removal of inorganic phosphorus and organic phosphorus, fundamentally solving the pollution problem of excessive phosphorus, and saving the environmental governance cost for additional removal of organic phosphorus.

[0007] 2. Technical Solutions

[0008] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

[0009] [Biochar Nanolanthanum Material]

[0010] In the first aspect of the present invention, a biochar nanolanthanum material for synchronously removing organic phosphorus and inorganic phosphorus is provided, which includes biochar and nanolanthanum loaded on the biochar. The biochar is bamboo biochar; the nanolanthanum is in the form of La(OH)3, the particle size of the nanolanthanum particles is 1 - 250 nm, and the loading amount of nanolanthanum is 3 wt% - 20 wt%; the pore size of the biochar nanolanthanum material is 1 - 30 nm, and the specific surface area is 100 - 250 m 2 / g.

[0011] It should be noted that the nanoscale La(OH)3 particles in the biochar nanolanthanum material have a high defect density and an incomplete crystal structure, with higher adsorption energy and stronger reaction activity, making the La(OH)3 nanoparticles loaded in the biochar nanolanthanum material have a stronger adsorption capacity for organic phosphonic acid and a closer combination. Moreover, different from the adsorption of organic phosphonic acid, after the La(OH)3 nanoparticles with a weak crystal structure in the biochar nanolanthanum material hydrolyze organic phosphonate esters, the generated hydrolysis product, orthophosphate, is fixed on the surface of the La(OH)3 nanoparticles, and the orthophosphate and lanthanum finally form LaPO4. At the same time, the medium-sized pore size in the biochar nanolanthanum is conducive to the diffusion of large organic phosphorus molecules to the action sites of lanthanum, providing spatial conditions for the adsorption and hydrolysis of organic phosphorus.

[0012] As a preference of any embodiment of the first aspect of the present invention, the size of the biochar nanolanthanum material is 0.5 - 5 mm.

[0013] The biochar nanolanthanum material within the above size range is conducive to industrial use and promotion.

[0014] [Synthesis Method of Biochar Nanolanthanum Material]

[0015] In the second aspect of the present invention, a synthesis method of the biochar nanolanthanum material provided in the first aspect of the present invention is provided, including the following steps:

[0016] S1: Dissolve lanthanum nitrate in alcohol, add biochar and stir to mix evenly, and obtain a solid mixture after filtering and drying.

[0017] S2: Add the solid mixture obtained in step S1 to a sodium hydroxide solution and stir at room temperature to obtain a solid-liquid mixture.

[0018] S3: Filter the solid-liquid mixture obtained in step S2, wash it with pure water until neutral, and dry it to obtain the biochar nanolanthanum material.

[0019] Bamboo biochar is hydrophilic and has a relatively small specific surface area. Lanthanum is easily adsorbed on bamboo biochar, facilitating the regulation of morphology by controlling the precipitation process in the later stage. The pore structure of bamboo biochar is not conducive to the crystal growth of lanthanum, and it is easy to form a weak crystal structure with a high defect density, thereby enhancing the hydrolysis removal of organic phosphorus. Moreover, the pores of bamboo biochar are relatively large, which is conducive to the diffusion of macromolecular organic phosphorus to the action sites of lanthanum, further enhancing the adsorption and hydrolysis removal of organic phosphorus.

[0020] As a preference for any implementation manner of the second aspect of the present invention, in the step S2, the concentration of the sodium hydroxide solution is 0.1 wt% to 10 wt%, the solid-liquid volume ratio of the solid mixture to the sodium hydroxide solution is 1:(30 - 80), and the stirring time is 4 h to 8 h.

[0021] More preferably, the concentration of the sodium hydroxide solution is 0.1 wt% to 5 wt%.

[0022] By adjusting the concentration of the precipitating agent sodium hydroxide solution, the crystallization process of La(OH)3 is controlled. A relatively high concentration of sodium hydroxide solution significantly increases the OH - concentration, resulting in a rapid reaction between La 3 + and OH - and a substantial increase in the nucleation rate. The crystal growth rate accelerates, and it is easy to form small-sized, low-crystallinity or amorphous La(OH)3 particles. At this time, the crystal structure is incomplete and the defect density is relatively high, thereby enhancing the adsorption and hydrolysis ability of organic phosphorus.

[0023] As a preference for any implementation manner of the second aspect of the present invention, in the step S1,

[0024] the alcohol is methanol or ethanol, and the concentration of the alcohol is 60% to 100%;

[0025] the concentration of lanthanum nitrate after being dissolved in alcohol is 30 - 200 g / L, and the mass ratio of lanthanum nitrate to biochar is 1:(0.5 - 5);

[0026] the stirring temperature is 30°C to 150°C, and the stirring time is 2 h to 24 h.

[0027] Lanthanide ions (such as La 3 +) have a high charge density and are easily hydrolyzed to form hydroxide precipitates. The hydroxyl group of alcohol can be coordinated with metal ions to delay the hydrolysis rate and improve the controllability of the reaction, thereby forming a stable solution system, creating conditions for lanthanum to enter biochar and form a lanthanum with a relatively high defect density weak crystal structure. By adjusting the temperature, the nucleation and growth rates are affected, determining the morphology of the material (such as nanoparticles, rods, flakes, etc.), and further affecting the adsorption of organic phosphorus and inorganic phosphorus.

[0028] When the concentration of alcohol is too low, there are not enough hydroxyl groups to coordinate and bind with metal ions, and a stable solution system cannot be formed. Lanthanum cannot enter the biochar and react with the precipitant sodium hydroxide in the form of lanthanum ions to form lanthanum with a weakly crystalline structure and a relatively high defect density. The prepared biochar nanolanthanum material has a poor effect on the removal of organic phosphorus.

[0029] Further preferably, the mass ratio of lanthanum nitrate to biochar is 1:(1 - 3).

[0030] Further preferably, the concentration of alcohol is 75% - 100%.

[0031] [Application of Biochar Nanolanthanum Material in Simultaneously Removing Organic Phosphorus and Inorganic Phosphorus in Water Body]

[0032] In the third aspect of the present invention, there is provided an application of the biochar nanolanthanum material provided in the first aspect of the present invention or the biochar nanolanthanum material obtained by the synthesis method provided in the second aspect of the present invention in simultaneously removing organic phosphorus and inorganic phosphorus in a water body, including the following steps: adding the biochar nanolanthanum material to the water body, adjusting the pH value of the water body to 3 - 8, and the stirring reaction time is greater than or equal to 24 h.

[0033] As a preference of any embodiment of the third aspect of the present invention, the dosage of the biochar nanolanthanum material relative to the water body is 0.1 - 5 g / L.

[0034] As a preference of any embodiment of the third aspect of the present invention, the phosphorus concentration of organic phosphorus in the water body is 1 - 2 mg P / L, the phosphorus concentration of inorganic phosphorus is 2.5 - 3.5 mg P / L, and the treatment capacity of the biochar nanolanthanum material for the phosphorus-containing wastewater is 150 BV - 300 BV. The treatment capacity means that the phosphorus concentrations of both organic phosphorus and inorganic phosphorus in the treated water body are less than 1 mg P / L.

[0035] It should be noted that mg P / L represents the mass of P in 1 L of water body.

[0036] As a preference of any embodiment of the third aspect of the present invention, the regeneration method of the biochar nanolanthanum material after adsorbing phosphorus includes the following steps:

[0037] A) Adding the biochar nanolanthanum material after adsorbing phosphorus to a 0.5 wt% - 5 wt% NaOH solution, with a solid-liquid ratio of 1 - 20 g / L, heating and shaking for a reaction time of greater than or equal to 24 h;

[0038] B) Washing the desorbed biochar with ultrapure water, filtering, and drying.

[0039] 3. Beneficial Effects

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] (1) In general, the biochar-supported nano-lanthanum composite materials in the prior art can only remove inorganic phosphorus. The biochar nano-lanthanum material provided by the present invention has nano-lanthanum in the form of La(OH)3, the particle size of the nano-lanthanum is 1-250 nm, and the loading amount of the nano-lanthanum is 3 wt% - 20 wt%; the pore size of the biochar nano-lanthanum material is 1-30 nm, and the specific surface area is 100-250 m 2 / g. In addition to having the performance of inorganic phosphorus adsorption, it also has the effect of organic phosphorus adsorption, and can simultaneously remove inorganic phosphorus and organic phosphorus.

[0042] This biochar nano-lanthanum material adsorbs and removes organic phosphorus by regulating the defective morphology of lanthanum. Especially for organophosphonates, it can be hydrolyzed and removed. At the same time, the relatively large pore channels of bamboo biochar are conducive to the diffusion of macromolecular organic phosphorus to the action sites of lanthanum, further strengthening the adsorption and hydrolysis of lanthanum on organic phosphorus; bamboo biochar can not only adsorb and remove a small part of organophosphonates, but also adsorb and remove the original and hydrolyzed inorganic phosphorus in the water body, and the two cooperate to remove organic phosphorus and inorganic phosphorus in the water body.

[0043] (2) The synthesis method of the biochar nano-lanthanum material provided by the present invention uses the "precursor introduction-in-situ precipitation method" to synthesize the biochar nano-lanthanum material. By adjusting the concentrations of the precipitant and alcohol and selecting a suitable biochar, the obtained biochar nano-lanthanum material is subjected to X-ray diffraction (XRD) test analysis. The results show that lanthanum exists in the form of La(OH)3, and its crystal form is wide and miscellaneous, indicating that its defect density is relatively high and the crystal structure is incomplete. It belongs to lanthanum with a weak crystal structure and a relatively high defect density. The present invention finds that this lanthanum with a defective structure is more conducive to the adsorption and hydrolysis removal of organic phosphorus. Moreover, the size of the loaded lanthanum nanoparticles is 5-200 nm and they are evenly dispersed, solving the problems of easy aggregation and inactivation of nano materials and difficult recovery. At the same time, the loading amount of lanthanum can be controlled by regulating the concentration of lanthanum nitrate and the mass ratio of biochar to lanthanum nitrate, thereby increasing the number of active sites and enhancing the adsorption capacity.

[0044] (3) The present invention finds that during the synthesis process of the biochar nano material, low-concentration alcohol is difficult to obtain lanthanum with a weak crystal structure and a relatively high defect density, and the organic phosphorus adsorption effect is poor. While high-concentration alcohol can obtain lanthanum with a weak crystal structure and a relatively high defect density, and the organic phosphorus adsorption effect is good.

[0045] (4) The synthesis method of the biochar nano-lanthanum material provided by the present invention is simple and convenient in the material synthesis process. Moreover, bamboo biochar as the carrier has a low price, which can reduce the sewage treatment cost and is conducive to industrial promotion and application.

[0046] (5) When the biochar nano-lanthanum material provided by the present invention is applied to sewage treatment, it can simultaneously remove organic phosphorus and inorganic phosphorus, which is beneficial to simplifying the sewage treatment steps and saving sewage treatment resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is the process flow chart of the preparation method of the present invention;

[0048] Figure 2a is the TEM image (500nm) of the biochar nano-lanthanum material La@C-1 prepared in Example 1 of the present invention;

[0049] Figure 2b :

[0050] The left figure is the TEM image (100nm) of the biochar nano-lanthanum material La@C-1 prepared in Example 1 of the present invention;

[0051] The right figure is the energy dispersive X-ray spectroscopy (EDS) scan image of the corresponding area of the left figure;

[0052] Figure 3 is the XRD pattern of the biochar nano-lanthanum material La@C-1 and bamboo biochar C prepared in Example 1 of the present invention;

[0053] Figure 4 is the TEM image (50nm) of the biochar nano-lanthanum material La@C-2 prepared in Example 2 of the present invention;

[0054] Figure 5 is the adsorption effect of the biochar nano-lanthanum materials La@C-1 and La@C-2 prepared in Examples 1 and 2 of the present invention on NTMP in the presence of different interfering ions;

[0055] Figure 6 is the adsorption effect of the biochar nano-lanthanum material La@C-2 and bulk commercial La(OH)3 prepared in Example 2 of the present invention on NTMP in the presence of different interfering ions;

[0056] Figure 7 [[ID=4)]is the adsorption effect of the biochar nano-lanthanum material La@C-2, La(OH)3 mixed with unloaded bamboo biochar (La + C) and bamboo biochar C prepared in Example 2 of the present invention on NTMP;

[0057] Figure 8 is the removal effect of the biochar nano-lanthanum material La@C-2, La(OH)3 mixed with unloaded bamboo biochar (La + C) and bamboo biochar C prepared in Example 2 of the present invention on p-NPP;

[0058] Figure 9The production rate of p-NP when the biochar nanolanthanum materials La@C-2, the mixture of La(OH)3 and unloaded bamboo biochar (La+C), and bamboo biochar C prepared in Example 2 of the present invention were used to remove p-NPP;

[0059] Among them, Figure 9 The small figure shows the removal efficiency of p-NP when the biochar nanolanthanum materials La@C-2, the mixture of La(OH)3 and unloaded bamboo biochar (La+C), and bamboo biochar C prepared in Example 2 of the present invention were used to remove p-NPP;

[0060] Figure 10 The residual amount of orthophosphate in water when the biochar nanolanthanum materials La@C-2, the mixture of La(OH)3 and unloaded bamboo biochar (La+C), and bamboo biochar C prepared in Example 2 of the present invention were used to remove p-NPP;

[0061] Figure 11 The adsorption performance of the biochar nanolanthanum material La@C-2 prepared in Example 2 of the present invention for inorganic phosphorus and organic phosphorus under actual application conditions. Detailed implementation manners

[0062] For those not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0063] As used herein, the term "about" is used to provide flexibility and imprecision associated with a given term, measurement, or value. Those skilled in the art can easily determine the degree of flexibility of a specific variable.

[0064] Concentrations, amounts, and other numerical data may be presented herein in a range format. It should be understood that such range formats are used merely for convenience and brevity and should be interpreted flexibly as including not only the explicitly recited numerical values as the limits of the range, but also all the individual numerical values or sub-ranges subsumed within the stated range as if each numerical value and sub-range were explicitly recited. For example, a numerical range of about 1 to about 4.5 should be interpreted as including not only the explicitly recited limit values of 1 to about 4.5, but also the individual numbers (such as 2, 3, 4) and sub-ranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that only recite one numerical value, such as "less than about 4.5", which should be interpreted as including all of the above values and ranges. In addition, this interpretation should apply regardless of the breadth of the described range or feature.

[0065] Any step described in any method or process claim (e.g., step S1, S2, S3... or step (1), (2), (3)... or step 1), 2), 3)...) can be performed in any order and is not limited to the order presented in the claim.

[0066] The method + function or step + function limitation is employed only when all of the following conditions exist in a particular claim limitation: a) The "method for..." or "step for..." is explicitly recited; b) The corresponding function is explicitly recited. The structure, material, or action supporting the method + function is explicitly recited in the description herein. Accordingly, the scope of the present invention should be determined solely by the appended claims and their legal equivalents, rather than by the description and examples given herein.

[0067] The present invention will be further described below in conjunction with specific embodiments.

[0068] Preparation materials:

[0069] La(NO3)3, ethanol, sodium hydroxide, nitrilotrimethylenephosphonic acid (NTMP), humic acid (HA), bulk commercial La(OH)3, disodium p-nitrophenyl phosphate (p-NPP), and NaH2PO4 were purchased from Nanjing Wanqing Chemical Glass Instruments Co., Ltd. Bamboo biochar (C, size 3 - 5 mm) was obtained commercially.

[0070] The digestion is specifically the HNO3-HClO4 digestion method, and the steps are as follows:

[0071] Accurately weigh 0.1 g of the material and place it in a 150 mL conical flask. After adding several glass beads, successively add 15 mL of HNO3 and 5 mL of HClO4, and slowly heat with an electric furnace until the solution boils. When all the solids in the solution are dissolved, continue heating until the solution is clear, and then turn off the electric furnace and let it cool naturally to room temperature to obtain the digestion solution.

[0072] Example 1

[0073] This example is a method for preparing biochar nanolanthanum materials using the process flow as Figure 1 shown, and the specific steps are as follows:

[0074] 1) Add 5 g of La(NO3)3 to 100 ml of 75% ethanol aqueous solution, and seal and stir to dissolve at 75 °C to obtain a lanthanum solution;

[0075] 2) Slowly add 10 g of bamboo biochar (C, 3 - 5 mm) material to the lanthanum solution prepared in step 1), and stir for 6 h until the reaction system is uniformly mixed to obtain a solid-liquid mixture;

[0076] 3) Filter the solid-liquid mixture obtained in step 2) until there is no liquid residue on the surface to obtain a solid mixture;

[0077] 4) Add the solid mixture obtained in step 3) to a 0.1 wt% sodium hydroxide solution and stir for 6 h. The volume ratio of the reaction solid to liquid is 1:65;

[0078] 5) Filter the mixture obtained in step 4), wash it with pure water until neutral, and dry it to obtain a biochar nanolanthanum material, named La@C-1.

[0079] The biochar nanolanthanum material prepared in this example is in the form of black blocks, with a size of 1-3 mm. The carrier bamboo biochar has a porous structure. The pore size measured by a fully automatic specific surface area and porosity analyzer (BET) is 5-20 nm, mostly mesopores (generally, the pore size range of mesopores is 2-25 nm). The specific surface area of the material is 167.2 m 2 / g. The large specific surface area and rich pore structure are beneficial to the adsorption and degradation of phosphorus by the material. The transmission electron microscope (TEM) image (500 nm) of La@C-1 is as Figure 2a shown. Using ImageJ statistics, it can be known that the particle size of La nanoparticles is about 5-200 nm. After digestion, the loading amount of lanthanum measured by inductively coupled plasma optical emission spectrometer (ICP-OES) is about 7.9 wt%, indicating that lanthanum is successfully loaded. The transmission electron microscope (TEM) image (100 nm) of La@C-1 and the energy dispersive X-ray spectroscopy (EDS) scan of the corresponding area are as Figure 2b shown. Lanthanum is uniformly distributed on the surface of the material carrier in the form of nanoparticles. The X-ray diffraction (XRD) test analysis of La@C-1 is as Figure 3 shown. Lanthanum exists in the form of La(OH)3, with a wide and complex crystal form and a high defect density.

[0080] Example 2

[0081] This example is a method for preparing a biochar nanolanthanum material using the process flow shown as Figure 1 below. The specific steps are as follows:

[0082] 1) Add 8 g of La(NO3)3 to 100 ml of absolute ethanol, and stir and dissolve it in a sealed manner at 75 °C to obtain a lanthanum solution;

[0083] 2) Slowly add 10 g of bamboo biochar (C, 3-5 mm) material to the lanthanum solution prepared in step 1), and stir for 6 h until the reaction system is evenly mixed to obtain a solid-liquid mixture;

[0084] 3) Filter the solid-liquid mixture obtained in step 2) until there is no liquid residue on the surface to obtain a solid mixture;

[0085] 4) The solid mixture obtained in step 3) was added to a 1 wt% sodium hydroxide solution and stirred for 6 h, and the reaction solid-liquid ratio was 1:50;

[0086] 5) The mixture obtained in step 4) was filtered and washed with pure water until neutral, and then dried to obtain a biochar nanolanthanum material, named La@C-2.

[0087] The biochar nanolanthanum material prepared in this example was in the form of black blocks with a size of 1-3 mm. The carrier bamboo biochar had a porous structure. The pore size measured by a fully automatic specific surface area and porosity analyzer (BET) was 5-20 nm, mostly mesopores (generally, the pore size range of mesopores is 2-25 nm), and the specific surface area of the material was 201.5 m 2 / g. The transmission electron microscope (TEM) image (50 nm) of La@C-2 is as Figure 4 shown. Using ImageJ statistics, it can be known that the particle size of La nanoparticles is about 5-200 nm. After digestion, the loading amount was measured by inductively coupled plasma optical emission spectrometer (ICP-OES) to be about 8.1 wt%, indicating that lanthanum was successfully loaded. The transmission electron microscope (TEM) image (100 nm) of La@C-2 and the energy dispersive X-ray spectroscopy (EDS) scan of the corresponding area are similar to Figure 2b that. X-ray diffraction (XRD) test analysis was performed on La@C-2, and the results were similar to Figure 3 that.

[0088] Test Example 1

[0089] This test example tested the effect of La@C-1 prepared in Example 1 on the static adsorption of organophosphorus in water under the condition of the presence of competitive ions. The specific steps were as follows:

[0090] 1) Prepare 5 groups of 100 ml of water to be treated containing both aminotrimethylenephosphonic acid (NTMP) and competitive ions. The competitive ions were Cl - , NO3 - , SO4 2- , HCO3 - , and humic acid (HA). Among them, the concentration of NTMP was controlled at 50 μmol / L, the concentration of competitive anions was 300 mg / L, and the initial pH was 7.0. At the same time, the water to be treated without competitive ions was used as a control group.

[0091] 2) The dosage of the biochar nanolanthanum material La@C-1 for the 6 groups of water to be treated was 0.5 g / L. After stirring and adsorbing at room temperature for 24 h, the supernatant was taken to measure the NTMP concentration, and the adsorption effect of the biochar nanolanthanum material La@C-1 was calculated.

[0092] The adsorption effect of the biochar nanolanthanum material La@C-1 is asFigure 5 As shown, HCO3 - has an obvious inhibitory effect on the adsorption of organic phosphorus by the biochar nano-lanthanum material. This is because HCO3 - ions inhibit the adsorption by competing for the adsorption sites of lanthanum (La) and form lanthanum carbonate precipitation to passivate the active sites.

[0093] Test Example 2

[0094] This test example tests the effect of the La@C-2 prepared in Example 2 on the static adsorption of organic phosphorus in water under the condition of the presence of competing ions. The specific steps are as follows:

[0095] 1) Prepare 5 groups of 100 ml of water to be treated containing both aminotrimethylenephosphonic acid (NTMP) and competing ions. The competing ions are Cl - , NO3 - , SO4 2- , HCO3 - , and humic acid (HA). Among them, the concentration of NTMP is controlled to be 50 μmol / L, the concentration of competing anions is 300 mg / L, and the initial pH is 7.0. At the same time, use the water to be treated without competing ions as the control group.

[0096] 2) The dosage of the biochar nano-lanthanum material La@C-2 in the 6 groups of water to be treated is 0.5 g / L. After stirring and adsorbing at room temperature for 24 h, take the supernatant to measure the NTMP concentration, and calculate the adsorption effect of the biochar nano-lanthanum material La@C-2.

[0097] The adsorption effect of the biochar nano-lanthanum material La@C-2 is as Figure 5 shown. Compared with La@C-1, La@C-2 shows better performance. This is because the material loading step is optimized by replacing the ethanol aqueous solution with pure ethanol. After the improvement, the adsorption amount of organic phosphorus by the material increases in the presence or absence of competing ions.

[0098] Test Example 3

[0099] This test example tests the effect of bulk commercial La(OH)3 on the static adsorption of organic phosphorus in water under the condition of the presence of competing ions. The specific steps are as follows:

[0100] 1) Prepare 5 groups of 100 ml of water to be treated containing both aminotrimethylenephosphonic acid (NTMP) and competing ions. The competing ions are Cl - , NO3 - , SO4 2- , HCO3 -, humic acid (HA). Among them, the concentration of NTMP was controlled at 50 μmol / L, the concentration of competing anions was 300 mg / L, and the initial pH was 7.0. At the same time, the water body to be treated without competing ions was used as the control group.

[0101] 2) The dosage of bulk commercial La(OH)3 in the 6 groups of water bodies to be treated was 0.5 g / L. After stirring and adsorbing at room temperature for 24 h, the supernatant was taken to measure the NTMP concentration, and the adsorption effect of bulk commercial La(OH)3 was calculated.

[0102] The adsorption effect of bulk commercial La(OH)3 is as Figure 6 shown. By comparing the adsorption effects of bulk commercial La(OH)3 and the biochar nanolanthana material La@C-2 prepared in Example 2 on NTMP in the presence of different interfering ions, it can be seen that compared with bulk commercial La(OH)3, the NTMP adsorption capacity of the biochar nanolanthana material La@C-2 is significantly improved (the adsorption capacity is increased from 43.8 μmol / g (P / La) to 67.7 μmol / g (P / La)), and the selectivity is higher (in the presence of coexisting anion concentration, the adsorption capacity is increased by 19.5 - 22.1 μmol / g La). This is mainly because La exists in the biochar nanolanthana material in the form of La(OH)3 nanoparticles with a weakly crystalline structure and a higher defect density.

[0103] It should be noted that μmol / g (P / La) represents the micromole amount of phosphorus adsorbed per 1 g of lanthanum.

[0104] Test Example 4

[0105] This test example tests the organic phosphorus removal performance of the biochar nanolanthana material La@C-2, bulk commercial La(OH)3, unloaded bamboo biochar (La + C) and bamboo biochar (C) prepared in Example 2. The specific steps are as follows:

[0106] 1) Prepare 3 groups of 100 ml of water bodies to be treated containing NTMP, control the NTMP concentration at 20 μmol / L, and the initial pH at 7.0.

[0107] 2) Add the biochar nanolanthana material La@C-2, unloaded bamboo biochar mixed with La(OH)3 (La + C) and unloaded bamboo biochar (C) to the 3 groups of water bodies to be treated containing NTMP respectively. The dosage is 0.5 g / L, and the NTMP adsorption capacity is measured after adsorption for 24 h.

[0108] Test Example 5

[0109] This test example tests the organic phosphorus removal performance of the biochar nanolanthanum material La@C-2 prepared in Example 2, the bulk commercial La(OH)3, the unloaded bamboo biochar mixed with La(OH)3 (La+C), and the unloaded bamboo biochar (C). The specific steps are as follows:

[0110] 1) Prepare 3 groups of water bodies to be treated containing disodium p-nitrophenyl phosphate (p-NPP), control the p-NPP concentration to be 100 μmol / L, and the initial pH to be 7.0.

[0111] 2) Add the biochar nanolanthanum material La@C-2, the unloaded bamboo biochar mixed with La(OH)3 (La+C), and the unloaded bamboo biochar (C) to the 3 groups of water bodies to be treated containing p-NPP respectively. The dosage is 0.5 g / L for all. After adsorption for 48 h, measure the removal amount of p-NPP, the generation amount and removal amount of the hydrolysis product p-nitrophenol (p-NP) in the desorbed mixture, and the residual amount of inorganic phosphorus.

[0112] The test results of Test Examples 4 and 5 are as Figures 7 - 10 shown. Compared with La+C, the NTMP adsorption capacity of the biochar nanolanthanum material La@C-2 is increased by about 10% (as Figure 7 shown), and the p-NPP removal rate is increased by about 25% (as Figure 8 shown). It can be seen from the generation rate of p-NP in Figure 9 that the removal of p-NPP includes not only the adsorption pathway but also the hydrolysis pathway. Since La@C-2, La+C, and C all have a certain adsorption effect on the hydrolysis product p-NP (as shown in the small figure in Figure 9 ), when comparing the hydrolysis rates, the p-NP adsorbed by the corresponding materials is also part of the hydrolysis products, but it is not released into the solution but adsorbed and fixed by the materials. Based on the above analysis and combined with Figure 8 and Figure 9 , by comparing the La@C-2 and La+C mixed materials, it is found that the biochar nanolanthanum material mainly removes organic phosphonates such as p-NPP through the hydrolysis pathway, and the La+C mixed material relies on the adsorption pathway to remove organic phosphonates such as p-NPP. That is, the hydrolysis rate of the biochar nanolanthanum material is increased by more than 40%, while the unloaded C material alone can only remove 8% of NTMP and about 10% of p-NPP through adsorption. And no orthophosphate is released into the solution during the whole process (as shown in Figure 10 ), that is, the orthophosphate generated by the hydrolysis of organic phosphorus is adsorbed by the materials at the same time.

[0113] In summary, the biochar nanolanthanum material is comprehensively superior to the equal amount of La+C mixed material and the simple unloaded bamboo biochar (C) in adsorbing organic phosphorus.

[0114] Test Example 6

[0115] This test example conducts a column adsorption test on the biochar nanolanthanum material La@C-2 prepared in Example 2 to test its adsorption performance for inorganic phosphorus and organic phosphorus under actual application conditions. The specific steps are as follows:

[0116] 1) Prepare a solution containing NaH2PO4 (3.1 mg P / L) and organic phosphorus (where NTMP (0.93 mg P / L) and p-NPP (0.31 mg P / L)) as the target treatment water body. The target treatment water body also contains Cl with a concentration of 1 mM each - , NO3 - , SO4 2- , HCO3 - and 9 mg / L of HA as competing ions.

[0117] 2) Take 100 g of the biochar nanolanthanum material La@C-2 as the column adsorption packing material, and control the flux of the target treatment water body to be 5 BV / h for the phosphorus adsorption performance test. Samples are taken at intervals of 10 BV to measure the organic phosphorus concentration in the effluent.

[0118] The adsorption performance of the biochar nanolanthanum material La@C-2 for inorganic phosphorus and organic phosphorus under actual application conditions is as Figure 11 shown. At a flow rate of 5 BV / h, the biochar nanolanthanum material can simultaneously remove inorganic phosphorus and organic phosphorus in the target treatment water body. In 180 BV, it ensures that the phosphorus concentrations of organic phosphorus and inorganic phosphorus in the effluent are both below 1 mg P / L, showing high application potential.

[0119] Finally, in one embodiment, the difference from Example 1 is only that the concentration of the ethanol aqueous solution is 30%, and the prepared biochar nanolanthanum material has a poor adsorption and removal effect on organic phosphorus.

[0120] The above content schematically describes the present invention and its implementation manners. This description is not restrictive. What is shown in the embodiments is only one of the implementation manners of the present invention, and the actual implementation manners are not limited thereto. Therefore, if those of ordinary skill in the art are inspired by it and design implementation manners and embodiments similar to this technical solution without creative efforts without departing from the purpose of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A biochar-nano lanthanum material for synchronous removal of organic phosphorus and inorganic phosphorus, comprising biochar and nano lanthanum loaded on the biochar, characterized in that: The biochar is bamboo biochar; The nano lanthanum is in the form of La(OH)3, the particle size of the nano lanthanum is 1 - 250 nm, and the loading amount of the nano lanthanum is 3wt% - 20wt%; The pore diameter of the biochar nanolanthanum material is 1 to 30 nm, and the specific surface area is 100 to 250 m 2 / g.

2. The biochar nanolanthanum material according to claim 1, wherein The size of the biochar-nano lanthanum material is 0.5 - 5 mm.

3. A method for synthesizing the biochar nano-lanthanum material for synchronously removing organic phosphorus and inorganic phosphorus according to claim 1 or 2, characterized in that, It includes the following steps: S1 Dissolve lanthanum nitrate in alcohol, add biochar and stir to mix evenly, and obtain a solid mixture after filtering and drying; S2 Add the solid mixture obtained in step S1 to a sodium hydroxide solution, and stir at room temperature to obtain a solid-liquid mixture; S3 Filter the solid-liquid mixture obtained in step S2, wash it with pure water until neutral, and dry it to obtain the biochar-nano lanthanum material.

4. The synthesis method of the biochar-nano lanthanum material for synchronous removal of organic phosphorus and inorganic phosphorus according to claim 3, characterized in that, In step S2, the concentration of the sodium hydroxide solution is 0.1wt% - 10wt%, the solid-liquid volume ratio of the solid mixture to the sodium hydroxide solution is 1:(30 - 80), and the stirring time is 4h - 8h.

5. The synthesis method of the biochar nano-lanthanum material for synchronously removing organic phosphorus and inorganic phosphorus according to claim 4, characterized in that, In step S1, The alcohol is methanol or ethanol, and the concentration of the alcohol is 60% - 100%; The concentration of lanthanum nitrate dissolved in alcohol is 30 - 200 g / L, and the mass ratio of lanthanum nitrate to biochar is 1:(0.5 - 5); The stirring temperature is 30°C - 150°C, and the stirring time is 2h - 24h.

6. The application of the biochar-nano lanthanum material according to claim 1 or 2 and the biochar-nano lanthanum material synthesized by the synthesis method according to any one of claims 3 - 5 in synchronous removal of organic phosphorus and inorganic phosphorus in water bodies.

7. The application according to claim 6, wherein It includes the following steps: Add the biochar-nano lanthanum material to the water body, adjust the pH value of the water body to 3 - 8, and the stirring reaction time is greater than or equal to 24 h.

8. The application according to claim 7, wherein The dosing amount of the biochar-nano lanthanum material relative to the water body is 0.1 - 5 g / L.

9. The application according to claim 7, characterized in that The phosphorus concentration of organic phosphorus in the water body is 1 - 2 mg P / L, the phosphorus concentration of inorganic phosphorus is 2.5 - 3.5 mg P / L, and the treatment capacity of the biochar-nano lanthanum material for the phosphorus-containing wastewater is 150 BV - 300 BV, and the treatment capacity means that the phosphorus concentrations of organic phosphorus and inorganic phosphorus in the treated water body are both less than 1 mg P / L.

10. The application according to claim 6, wherein The regeneration method of the biochar-nano lanthanum material after adsorbing phosphorus includes the following steps: A) Add the biochar-nano lanthanum material after adsorbing phosphorus to a 0.5wt% - 5wt% NaOH solution, the solid-liquid ratio is 1 - 20 g / L, and the heating and shaking reaction time is greater than or equal to 24 h; B) Wash the desorbed biochar with ultrapure water, filter it, and dry it.

Images