阅读说明：本技术 负载纳米零价锰生物炭的制备方法及应用 (Preparation method and application of nano zero-valent manganese loaded biochar ) 是由 龙建友 彭丽瑚 柯艳阳 陈思浩 李伙生 郑一杰 陈子楷 叶容川 黄涓溪 肖唐付 于 2021-08-18 设计创作，主要内容包括：本发明公开了一种负载纳米零价锰生物炭的制备方法及应用,所述生物炭以香蕉皮为材料通过碳热法制备,在所述生物炭的表面或孔隙中负载有纳米零价锰；所述生物炭与零价锰的负载比例为1:0.3。所述生物炭对铊离子吸附符合二级动力学模型,当含铊废水pH为10,水温度为15℃时,每1L含铊废水投加2g所述生物炭,可有效吸附含铊废水中的铊离子。(The invention discloses a preparation method and application of a nano zero-valent manganese-loaded biochar, wherein the biochar is prepared by taking banana peel as a material through a carbothermic method, and nano zero-valent manganese is loaded on the surface or in pores of the biochar; the load ratio of the biochar to the zero-valent manganese is 1: 0.3. The adsorption of the biological carbon to thallium ions accords with a two-stage kinetic model, and when the pH value of thallium-containing wastewater is 10 and the water temperature is 15 ℃, 2g of the biological carbon is added to every 1L of thallium-containing wastewater, so that the thallium ions in the thallium-containing wastewater can be effectively adsorbed.)

1. The charcoal is characterized in that the charcoal is prepared by taking banana peel as a material through a carbothermic method, and the surface or pores of the charcoal are loaded with nano zero-valent manganese; the method for loading the nano zero-valent manganese comprises the following steps: adding the biochar into an aqueous solution containing divalent manganese, slowly adding an aqueous solution containing tetrahydroborate, washing with water, centrifuging, and freeze-drying.

2. The nano zero-valent manganese-loaded biochar of claim 1, wherein the loading ratio of the biochar to zero-valent manganese is 1: 0.3.

3. The nano zero-valent manganese-loaded biochar according to claim 1, wherein the aqueous solution containing divalent manganese is an aqueous solution of manganese sulfate; the aqueous solution containing tetrahydroborate is an aqueous solution of sodium borohydride or potassium borohydride.

4. The nano zero-valent manganese-loaded biochar of claim 1, having a specific surface area of 21.6317m²G, mean pore diameter of 2.1388nm, pore volume of 0.007534cm³/g。

5. The nano zero-valent manganese-loaded biochar of claim 1, the method for preparing the biochar by a carbothermic method being: drying and crushing banana peel, sieving with 100 mesh sieve, placing in a tubular resistance furnace, heating at 500 deg.C for 1 hr, and introducing nitrogen gas for 30 min.

6. Use of nano zero valent manganese loaded biochar according to anyone of claims 1 to 5 in the treatment of thallium containing wastewater.

7. The use of claim 6, wherein the adsorption of monovalent thallium by the nano zero-valent manganese-loaded biochar conforms to a two-stage kinetic model.

8. Use according to claim 6 characterized in that the amount of loaded nano zero valent manganese biochar dosed per liter of thallium containing wastewater is between 1 and 2 g.

Technical Field

The invention belongs to the technical field of sewage treatment, relates to preparation of composite biochar, and particularly relates to a preparation method of loaded nano zero-valent manganese biochar and application of the loaded nano zero-valent manganese biochar in thallium-containing wastewater treatment.

Background

The heavy metal pollution problem in the wastewater is increasingly severe, and the heavy metal pollution not only affects the water environment, but also causes non-negligible influence on the health of human beings and other animals and plants. The heavy metal pollution of the water body has a plurality of sources and great treatment difficulty. Thallium, a silvery white, highly toxic, fugitive element. Thallium content in natural environment is very low, and in recent years, human industry activities are abundant, and thallium pollution risk is increased. In recent years, thallium pollution and thallium poisoning events are attracting attention, and patients with thallium poisoning show symptoms such as hair loss, nausea and vomiting, and the functions of liver and kidney organs are damaged. Therefore, the thallium contamination problem is not easy to solve.

At present, the main methods for removing thallium are chemical precipitation method, ion exchange method, adsorption method, etc., wherein the most used methods are adsorption method, mainly comprising activated carbon adsorption, biochar adsorption, composite material adsorption, nano metal compound adsorption, etc. The adsorption method is a common way for removing heavy metals in water environment because the adsorbent has little or no harm to the environment. The biochar taking the biomass as the raw material has the advantages of low price, simple manufacturing method, high cost performance and good prospect. The biochar contains rich functional groups, has a porous structure, is stable, has a good effect of treating environmental problems, and gradually becomes a research focus in the environmental field. Patent CN108435135A discloses a preparation method of watermelon peel biochar, which comprises the following steps: (1) pretreating watermelon peels: drying the watermelon peel to obtain watermelon peel powder; (2) carbonizing: carbonizing the watermelon peel powder obtained in the step (1) for 0.5-1.5 hours at a carbonization temperature of 400-600 ℃ in a nitrogen atmosphere to obtain the watermelon peel biochar; the watermelon peel biochar prepared by the preparation method disclosed by the invention has the highest adsorption efficiency on thallium ion, and is simple in process and low in preparation cost.

Although the adsorption method can remove heavy metal ions in industrial wastewater to a certain extent, the method for removing heavy metal thallium by using charcoal-loaded zero-valent manganese is unknown. Therefore, by providing the preparation method and application of the loaded nano zero-valent manganese biochar, the prepared loaded nano zero-valent manganese biochar can effectively remove thallium in a water environment by combining the characteristics of high efficiency, economy and environmental protection of biochar, so that a new idea is provided for preparation of a composite biochar material and adsorption of heavy metal thallium.

Disclosure of Invention

In order to deeply research and develop an efficient and low-cost adsorption material for adsorption treatment of heavy metal pollution of a water body, the invention provides a preparation method of a loaded nano zero-valent manganese biochar, which analyzes the adsorption effect of the biochar on a thallium solution in detail under different reaction time, solution pH value, zero-valent manganese adding amount, thallium solution initial concentration and reaction temperature, and analyzes the adsorption mechanism of the biochar by utilizing XPS, FT-IR, TEM and other characterization means, isothermal adsorption and dynamics.

Based on the above purpose, the invention provides a preparation method of nano zero-valent manganese-loaded biochar and application thereof in thallium-containing wastewater to remove Tl ions in thallium-containing industrial wastewater.

The preparation method of the loaded nano zero-valent manganese biochar specifically comprises the following steps: according to the mass parts, 350 parts of water are taken, 2.5 parts of manganese sulfate monohydrate is dissolved, the biochar prepared from banana peel is slowly added, 3.8 parts of sodium borohydride is added into a solution containing manganese sulfate and biochar at the speed of 250rpm by using a peristaltic pump, the prepared substance is washed for 3 times after 30min, and freeze-drying is carried out after centrifugation.

The preparation method is further detailed as follows: loading according to the proportion of the biochar to manganese being 1: 0.3. 2.5g of manganese sulfate monohydrate, 8.3g of biochar and 3.8g of sodium borohydride were weighed. 350ml of water is added into a beaker, then manganese sulfate is dissolved, then biochar is slowly added, and sodium borohydride or potassium borohydride is added into the beaker containing the manganese sulfate and the biochar by a peristaltic pump at the speed of 250 rpm. After the addition, the time was 30 minutes. And washing the prepared substance for 3 times, centrifuging, putting the substance into a refrigerator, putting the substance into a freeze dryer, freeze-drying, putting the substance into a sealing bag, discharging air, and putting the substance into a dryer for storage to obtain the nano zero-valent manganese-loaded biochar.

The invention also provides a preparation method of the banana skin biochar, which specifically comprises the following steps: selecting cut banana peel as raw material, placing into oven at 105 deg.C, oven drying for 12h, sieving with crusher (100 mesh), placing into ark, placing into tube furnace, heating at 500 deg.C for 5 deg.C per minute, pyrolyzing for 1h, and introducing nitrogen for 30 min. And taking out the boat after the tube furnace is cooled to room temperature, and obtaining the black carbonized product, namely the banana skin biochar.

Further, when the initial pH of the thallium-containing wastewater is 10 and the reaction temperature is 15 ℃, 2g of thallium-containing ammonia nitrogen wastewater is added into 1L of thallium-containing ammonia nitrogen wastewater, and the maximum adsorption effect of the nanometer zero-valent manganese-loaded biochar on thallium ions in the thallium-containing wastewater can be realized after 1h of mixing.

Compared with the prior art, the invention has the following beneficial effects or advantages: the invention provides a preparation method and application of loaded nano zero-valent manganese biochar, which comprises the steps of putting the loaded nano zero-valent manganese biochar into thallium-containing wastewater, utilizing redox, ion exchange and complexation to realize adsorption treatment on thallium ions in the wastewater, and having cheap raw materials and simple preparation method.

Drawings

FIG. 1 is SEM scanning electron microscope image of nanometer zero-valent manganese-loaded biochar, wherein (a) is the amplification of 100 times before thallium ion adsorption by the nanometer zero-valent manganese-loaded biochar, and (b) is the amplification of 100 times after thallium ion adsorption by the nanometer zero-valent manganese-loaded biochar;

FIG. 2 is a front and back infrared spectrogram of adsorption of thallium ions by the loaded nano zero-valent manganese biochar;

FIG. 3 is XPS full spectrum before and after adsorption of thallium ions by the nano zero-valent manganese-loaded charcoal;

FIG. 4 is an XRD (X-ray diffraction) pattern before thallium ions are adsorbed by the nano zero-valent manganese-loaded charcoal;

FIG. 5 is an XRD diagram of loaded nano zero-valent manganese biochar after adsorption of thallium ions;

FIG. 6 is Zeta potential diagram of the loaded nano zero-valent manganese biochar;

FIG. 7 is a kinetic model diagram of thallium ion adsorption by the nano zero-valent manganese-loaded biochar;

FIG. 8 is a thallium ion isothermal adsorption model of loaded nano zero-valent manganese biochar adsorption;

FIG. 9 is a graph showing the influence of the dosage of the loaded nanoscale zero-valent manganese biochar on the removal of heavy metal thallium;

FIG. 10 is a graph showing the effect of initial pH on the removal of heavy metal thallium by the loaded nanoscale zero-valent manganese biochar;

FIG. 11 is a graph showing the effect of pH on the removal of heavy metal thallium by the loaded nanoscale zero-valent manganese biochar after reaction;

FIG. 12 is a diagram showing the effect of reaction temperature on the removal of heavy metal thallium by the loaded nanoscale zero-valent manganese biochar;

FIG. 13 is a diagram showing the influence of coexisting ions on the removal of heavy metal thallium by the loaded nanoscale zero-valent manganese biochar.

Detailed Description

The following examples are given to illustrate the technical aspects of the present invention, but the present invention is not limited to the following examples.

Example 1

This example provides an adsorption test of thallium ions by the loaded nanoscale zero-valent manganese biochar.

The preparation method of the banana peel biochar comprises the steps of selecting cut banana peels as raw materials, placing the banana peels into a drying oven at 105 ℃ for drying for 12 hours, then sieving the banana peels by using a crusher (100 meshes), placing the banana peels into a square boat after sieving, placing the square boat into a tubular furnace, setting the temperature at 500 ℃, carrying out pyrolysis for 1 hour at the rate of heating at 5 ℃ per minute, and introducing nitrogen for 30 minutes. And taking out the square boat after the tubular furnace is cooled to room temperature, filling the prepared black carbonized product into a sealing bag, exhausting air, and then putting the sealed bag into a dryer for storage.

The preparation method of the loaded nano zero-valent manganese biochar comprises the step of loading according to the proportion of biochar to manganese of 1: 0.3. 2.5g of manganese sulfate monohydrate, 8.3g of biochar and 3.8g of sodium borohydride were weighed. 350ml of water is added into a beaker, then manganese sulfate is dissolved, then biochar is slowly added, and sodium borohydride is added into the beaker containing the manganese sulfate and the biochar by a peristaltic pump at the speed of 250 rpm. After the addition, the time was 30 minutes. The reaction of the solution is as follows:

and (3) washing the prepared substance for 3 times, centrifuging, putting the substance into a refrigerator, putting the substance into a freeze dryer, freeze-drying, putting the substance into a sealing bag, discharging air, putting the air into a dryer, and storing the substance as the loaded nano zero-valent manganese biochar.

(1) Characterization and analysis of loaded nano zero-valent manganese biochar

FIG. 1 is SEM scanning image of loaded nanometer zero-valent manganese biochar, wherein (a) is amplification of 100 times before thallium ion adsorption by the loaded nanometer zero-valent manganese biochar, and (b) is amplification of 100 times after thallium ion adsorption by the loaded nanometer zero-valent manganese biochar. Table 1 shows the EDS analysis results before and after adsorption of the nano zero-valent manganese-loaded biochar.

TABLE 1 EDS analysis before and after adsorption of nano zero-valent manganese-loaded biochar

The microscopic morphology of the nano zero-valent manganese-loaded biochar can be observed by using a Scanning Electron Microscope (SEM), and particularly shown in figure 1. As can be seen, the composite material before reaction is granular, and the surface is slightly rough; after the reaction, the loaded nano zero-valent manganese biochar can be agglomerated into larger particles and generates Tl element, other appearances are not changed greatly, and the composite biochar is stable. The specific gravity of the Mn element increases due to the decrease in the percentage of the O element, and thus it is presumed that the oxygen-containing functional group participates in the adsorption reaction.

(2) Fourier FTIR analysis of loaded nano zero-valent manganese biochar

FIG. 2 is an infrared spectrogram before and after thallium adsorption, wherein BC @ Mn represents the loaded nano zero-valent manganese biochar. As can be seen from FIG. 2, the absorption peak before and after thallium adsorption of the nano zero-valent manganese-loaded biochar is 1500-4000 cm^-1Basically consistent, 500-1500 cm after adsorption^-1The diffraction peak of (A) is more than that before adsorption, and the damage effect on the composite material after thallium adsorption is small. 3432cm^-1The reason is that sigma O-H stretching vibration and a wide absorption peak indicate that crystallized water and physically adsorbed water exist in the adsorbent, and OH is a strong polar group, so that the association phenomenon of the hydroxyl compound is very remarkable. 2353cm^-1Is prepared from CO₂Induced absorption peaks; 1861cm-¹Is the out-of-plane curvature of the carbonate; 1641cm^-1Indicates the presence of carbon groups (C ═ O) in the system. 1405cm^-1Symmetric stretching of the position of-COO-; after the reaction, the concentration of the reaction solution was 1097cm^-1The peak appears, the intensity is weak, and the vibration is C-O-C asymmetric stretching vibration. 556cm before loading nano zero-valent manganese biochar to adsorb thallium^-1Peak of (1) and absorption of thallium at 620cm^-1The peak of (2) may be a stretching vibration of Mn-O. The functional groups of the material that play a major role in the adsorption reaction are hydroxyl, carboxyl and ether groups. The functional groups can provide active sites for the biochar to fix thallium, and bind the thallium element in a complexing mode.

(3) XPS analysis of nano zero-valent manganese loaded biochar X-ray photoelectron spectroscopy technology

The elemental composition and valence state of the biochar surface were analyzed by X-ray photoelectron spectroscopy XPS, and the results are shown in fig. 3. The XPS full spectrum and the element composition table of FIG. 3 show that the elements appearing on the surface of the loaded nano zero-valent manganese biochar mainly consist of C, O, Mn, the elements are basically unchanged before and after adsorption, C elements are enhanced after adsorption, and thallium elements are added;and the Cl, K, O and Na components are reduced. 284eV of the spectrum of the C1s of the loaded nano zero-valent manganese biochar represents C/C-C (SP 2 hybridization of carbon atoms, functional groups of the biochar), which indicates that the surface of the loaded nano zero-valent manganese biochar has a relatively good aromatic structure. The peak of O1s of the loaded nano zero-valent manganese biochar is positioned at the peak of 532.18eV, and represents oxygen in the metal oxide. The original biochar contains few metal oxygen atoms, and metal elements are obviously increased after zero-valent manganese is loaded and monovalent thallium is adsorbed. And the 2p peaks of Mn are at 642.44 and 654.2eV, which represent Mn (II) and Mn (IV), respectively. This indicates that the Mn element exists in different valence states on the surface of the biochar, and the loaded zero-valent manganese is oxidized, probably because the surface zero-valent manganese is oxidized by oxygen in the air during the experimental process or due to improper preservation. Tl appears on the surface of the adsorbed material⁺Two peaks, each representing Tl⁺And Tl₂O。

(4) X-ray diffraction XRD analysis of nano zero-valent manganese loaded biochar

Fig. 4 is an XRD pattern before adsorption, and fig. 5 is an XRD pattern after adsorption. Before adsorption, the existence of some small hetero peaks is observed in the nano zero-valent manganese-loaded biochar material, wherein the most main peak is manganese carbonate. For the nano zero-valent manganese-loaded biochar (PDF #44-1472), diffraction peaks appear at 24.2 degrees, 31.4 degrees, 41.4 degrees, 51.7 degrees and 51.8 degrees, and the crystal face indexes are respectively (012), (104), (113), (018) and (116). After adsorption, a plurality of MnCO strips also appear on the loaded nano zero-valent manganese biochar (PDF #83-1763)₃The number of diffraction peaks of (1) is small as at 24.2 °, 31.4 ° and 51.7 °, and the crystal plane indices thereof are (012), (104), (018), respectively.

(5) Specific surface area BET analysis of loaded nano zero-valent manganese biochar

The specific surface area of the adsorbent is an evaluation factor of the adsorption performance. The larger the specific surface area is, the more adsorption sites are provided, and the adsorption performance is correspondingly improved. Since metal ions can diffuse into the adsorption pores of the biochar, increasing BET surface area and pore volume can increase the adsorption capacity of the biochar. The specific surface area of the nano zero-valent manganese-loaded biochar was analyzed, and the results are shown in table 2.

TABLE 2 BET surface area, pore size and pore volume of the nano zero-valent manganese-loaded biochar

The surface area of the loaded nano zero-valent manganese biochar is 21.6317m²G, average pore diameter 2.1388nm, pore volume 0.007534. The specific surface area of the loaded nano zero-valent manganese biochar is small. The reason is hypothesized that the loaded zero-valent manganese preferentially occupies the surface and the microporous structure of the loaded nano zero-valent manganese biochar, so that the specific surface area of the loaded nano zero-valent manganese biochar is reduced.

(6) Zeta potential analysis of loaded nano zero-valent manganese biochar

The Zeta potential diagram of the loaded nano zero-valent manganese biochar is shown in figure 6, and has a peak near 0mV, so the material is an electrically neutral particle, and has large charge and better stability.

(7) Dynamic analysis of loaded nano zero-valent manganese biochar

Two 250mL beakers were taken and 130mL of Tl each having an initial concentration of 10ppm was added to each of the beakers⁺After the pH of the solution is adjusted to 10, adding a rotor, and placing a beaker on a magnetic stirrer; accurately weighing the loaded nano zero-valent manganese biochar by an electronic balance, keeping the dosage of 1.5g/L, and sampling every 0.5, 1, 2, 5, 10, 15, 30, 60, 120, 240 and 480 min.

Explaining the loaded nano zero-valent manganese biochar and Tl by fitting a primary kinetic model and a secondary kinetic model⁺With possible adsorption mechanisms. The kinetic experiment reflects the change of the relation between the adsorption rate and the adsorption time.

The nanometer zero-valent manganese biochar pair Tl is calculated according to the following formula⁺Removal rate and adsorption amount of (3).

The formula of the adsorption rate is as follows:

the formula of the adsorption amount is as follows:

wherein C is₀Initial concentration of thallium (mg/L), C_tThe thallium concentration (mg/L) at the reaction time t, V the volume of the thallium solution treated (L), and m the mass of the adsorbent (g).

The results obtained by the calculation were substituted into the Lagergren primary kinetic model and the Lagergren secondary kinetic model to draw adsorption kinetic curves, and the results are shown in fig. 7.

The Lagergren first order kinetic model is:

q_t＝q_e(1-e^-at)

the Lagergren secondary kinetic model is:

wherein q is_eThe adsorption capacity (mg/g) at adsorption equilibrium, q_tThe adsorption amount (mg/g) at the reaction time t, t the reaction time (min), and a the first-order kinetic adsorption constant (min)^-1) And b is the second order kinetic adsorption constant (min)^-1)。

The kinetic model obtained according to the above formula is shown in table 3.

Table 3, dynamic model of absorption of thallium ions by loaded nano zero-valent manganese biochar

As can be seen from FIG. 7 and Table 3, the adsorption rate of the biochar loaded with nano zero-valent manganese to thallium ions is higher, the adsorption amount is rapidly increased 30min before the reaction, and the adsorption saturation is reached near 60 min.

Correlation coefficient R of first order kinetic model fitting²At 0.808, the matching degree of the adsorption process and a first-stage kinetic model is not high, and the theoretical saturated adsorption quantity of the adsorption process is different from experimental data. Fitting twoCorrelation coefficient R of the order dynamics model²Is 0.997. The fitting result shows that the experimental data basically accord with a two-stage dynamic model curve, the deviation is small, and the nano zero-valent manganese biochar is loaded to low-concentration Tl⁺The adsorption effect of the method can be well fitted by using a second-order fitting curve, so that the second-order kinetic model can better show the kinetic process of thallium adsorption of the loaded nano zero-valent manganese biochar relative to the first-order kinetic model. Indicating that the adsorption rate is proportional to the square of the thallium concentration over a range of concentrations, it can be concluded that the adsorption process is dominated by chemisorption because the formation of chemical bonds is the major factor affecting the second-order kinetic adsorption.

Along with the increase of the contact time of the loaded nano zero-valent manganese biochar and thallium ions, the adsorption amount of the loaded nano zero-valent manganese biochar to the thallium-containing solution is increased. When the adsorption sites loaded with the nano zero-valent manganese biochar are basically filled, the maximum adsorption capacity is reached at the moment. The speed of the adsorption process gradually changes from high to low until the adsorption process reaches adsorption equilibrium.

The experiments show that the adsorption concentration of the loaded nano zero-valent manganese biochar is 10mg/L of Tl⁺The solution is a rapid adsorption reaction in the initial stage of the reaction, the adsorption amount of thallium is rapidly increased, and when the reaction time is 60min, the adsorption equilibrium is basically reached, and the adsorption rate of thallium reaches 68.7%.

(8) Isothermal adsorption line analysis of loaded nano zero-valent manganese biochar

Accurately weighing 12 parts of 0.030g loaded nano zero-valent manganese biochar by using an electronic analytical balance, preparing two groups of parallel samples, respectively taking 20ml of thallium liquid with the concentrations of 5 mg/L, 10mg/L, 20ml, 30 mg/L, 50 mg/L and 100mg/L into a centrifuge tube, putting the centrifuge tube into a shaking table, setting the reaction temperature to be 25 ℃, the rotation speed to be 200rpm and the reaction time to be 30 min.

At a certain temperature, when the adsorption reaches the equilibrium, the adsorbate concentration C in the solution is expressed by an adsorption isotherm_eWith adsorbent adsorption q_eThe relationship (2) of (c). Therefore, the characteristics of the loaded nano zero-valent manganese biochar are analyzed by adopting a Langmuir adsorption isotherm and a Freundlich adsorption isotherm.

Langmuir adsorption isotherm formula:

freundlich adsorption isotherm:

wherein, C_eThe concentration of thallium (mg/L) at adsorption equilibrium, q_eQ is the amount of adsorption (mg/g) at adsorption equilibrium_mIs the maximum adsorption capacity (mg/g) of the adsorbent, K_LIs Langmuir adsorption constant (L/mg), K_F1/n is an indication of the degree of surface unevenness or adsorption strength for the Freundlich adsorption constant.

Fitting Tl Using Langmuir and Freundlic models⁺The isotherms were adsorbed and the fitting results are shown in fig. 8. Coefficient of determinacy (R) of Langmuir isothermal model²0.948) is higher than the coefficient of determination (R) of Freundlich model²0.905) and the fitted saturated adsorption capacity is basically consistent with the experimental data, thereby illustrating that the Langmuir isothermal adsorption model can better describe the adsorption mechanism and illustrating that the loaded nano zero-valent manganese biochar is used for Tl⁺The adsorption reaction of (a) is dominated by monolayer adsorption.

(9) Influence of nano zero-valent manganese-loaded charcoal dosage on heavy metal thallium removal

Accurately weighing 0g, 0.0050g, 0.010g, 0.020g, 0.0300g and 0.0400g of loaded nano zero-valent manganese biochar respectively by using an electronic balance, accurately transferring 20ml of 10ppm thallium-containing solution into a 50ml centrifuge tube by using a liquid transfer gun, putting the centrifuge tube into a shaking table, setting the reaction temperature to be 25 ℃, the rotation speed to be 250rpm and the reaction time to be 30min, taking out, adding 1% HNO₃Taking 10ml thallium stock solution as blank sample, adding 1% HNO₃And (5) storing. And measuring the content of the residual thallium in the solution by adopting an inductively coupled plasma spectral generator (ICP), and calculating the adsorption capacity of the composite material to the thallium.

Analysis of the amount of drug administered can be seen in FIG. 9And obtaining R by linear fitting of experimental data of the dosage²0.954, errors in the experimental process may be errors in weighing, instrumentation. 10mg/LTl keeping adsorbing 20ml⁺The solution is not changed, and the loaded nano zero-valent manganese biochar pair Tl is added along with the increase of the dosage of the loaded nano zero-valent manganese biochar⁺The removal rate of the solution is increased, and the adsorption saturation is gradually reached. The removal rate of the loaded nano zero-valent manganese biochar when the dosage is approximately 1.0g/L is close to 60%, the removal effect of 1.5 g/L-2.0 g/L dosage on thallium is 76% -79%, the change is small, and the dosage of 1.5g/L is comprehensively considered in the following experiments.

(10) Influence of initial pH on removal of heavy metal thallium by nano zero-valent manganese loaded biochar

Adjusting the pH value of 10ppm thallium solution to 2, 4, 6, 7, 8 and 10 by using sodium hydroxide and dilute nitric acid, accurately transferring 20ml of thallium solution with different pH values into a 50ml centrifuge tube by using a liquid transfer gun, accurately weighing 12 parts of 0.030g loaded nano zero-valent manganese biochar by using a balance, preparing two groups of parallel samples and a group of blank samples, respectively putting the materials into the 50ml centrifuge tube, and obtaining an experimental result shown in figure 10.

The pH of the solution can affect the surface charge of the loaded nano zero-valent manganese biochar, thereby affecting the rate of the reduction reaction. As can be seen from FIG. 10, the Tl was varied under the same conditions as those of the amount of the applied drug, the temperature, and the thallium solution concentration⁺The initial pH of the solution shows that the nano zero-valent manganese biochar composite material pair Tl is loaded under the alkaline condition (the pH is 10)⁺The solution has higher adsorption efficiency, the pH is gradually increased from pH 2 to pH 10, the thallium removal rate is also gradually increased, and the removal rate reaches 68.58% at the maximum at pH 10.

(11) Influence of pH after reaction on removal of heavy metal thallium by loaded nano zero-valent manganese biochar

Respectively putting 20ml of 10ppm thallium-containing solution into a 50ml centrifuge tube, accurately weighing 12 parts of 0.030g loaded nano zero-valent manganese biochar by using an electronic balance, adding the solution into the centrifuge tube, putting the solution into a shaking table, setting the reaction temperature to be 25 ℃, the rotation speed to be 250rpm, setting the reaction time to be 30min, and taking out the solution after the reaction is finished. The thallium solutions in different centrifuge tubes were adjusted to pH 2, 4, 6, 7, 8, 10 using sodium hydroxide as base and dilute nitric acid as acid, respectively, and the removal rate of thallium in each solution was recorded under different adjustments, the results are shown in fig. 11.

The solution pH was adjusted after the adsorption reaction and its effect on thallium removal was studied. As can be seen from fig. 11, the adsorption effect of the material on thallium is relatively good under both acidic (pH 2) and alkaline (pH 10), and the removal rate is improved compared to the initial pH, and is 66.67% under acidic (pH 2) and 74.04% under alkaline (pH 10); after the reaction, the pH value of the thallium solution is adjusted to 7 and 8, and the removal rate is greatly reduced to about 40%.

(12) Influence of reaction temperature on removal of heavy metal thallium by loaded nano zero-valent manganese biochar

Accurately weighing 10 parts of 0.030g of nano zero-valent manganese-loaded biochar by using an electronic balance, accurately transferring 20ml of 10ppm thallium-containing solution by using a liquid transfer gun, respectively adding the solution into 50ml centrifuge tubes, respectively placing the solution into a shaking table, adjusting the rotating speed to 200 r/min, respectively changing the reaction temperature to 20 ℃, 25 ℃, 30 ℃, 35 ℃ and 40 ℃ and the reaction time to 30min, and then taking the carbon out of the shaking table, wherein the experimental result is shown in figure 12.

As can be seen from FIG. 12, the adsorption effect of the loaded nano zero-valent manganese biochar in the 5 temperature ranges is between 66% and 69%, and the reaction temperature is opposite to Tl⁺The adsorption effect of the solution is not greatly influenced, and the adsorption effect of the loaded nano zero-valent manganese biochar on the thallium solution is the best under the low-temperature condition (15 ℃).

(13) Influence of coexisting ions on removal of heavy metal thallium by loaded nano zero-valent manganese biochar

A10 ppm thallium solution was prepared, adjusted to an initial pH of 10, NaNO₃、MgSO₄And CaCl₂The concentration is 0.1, 0.2, 0.5, 0.8 and 1.0mg/L, 1.5g/L of the loaded nano zero-valent manganese biochar is respectively added into the solution, and the sampling is carried out after the solution is kept stand for 5 min.

Under the condition of optimal initial pH, different cations with different concentrations are respectively added. As can be seen from FIG. 13, Na⁺、Ca²⁺、Mg²⁺The three ions load the nanometer zero-valent manganese biochar pair Tl along with the increase of the concentration⁺The removal rate of (b) also gradually increases. Relative to each otherIn other words, Mg²⁺Adsorbing Tl for nano zero-valent manganese loaded biochar⁺Has obvious promoting effect when Mg²⁺When the concentration reaches 1.0mg/L, the thallium removal rate can reach 88.35% at most. And Ca²⁺The influence on the adsorption process is small, the maximum removal efficiency is achieved when the concentration is 1.0mg/L, and the removal rate is 75.42%. However, in contrast to the data for initial pH of 10 and 1.5g/L of drug, Na was added at different concentrations⁺For Tl⁺The adsorption effect of the solution is small.

As described above, the present invention can be preferably implemented, and the above-mentioned embodiments only describe the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various changes and modifications of the technical solution of the present invention made by those skilled in the art without departing from the design spirit of the present invention shall fall within the protection scope defined by the present invention.