A sulfur-modified zero-valent silicon composite material, its preparation method and application

Abstract

The present invention relates to a sulfurized modified zero-valent silicon composite material, a preparation method thereof and an application thereof. The sulfurized modified zero-valent silicon composite material is directly obtained by ball milling zero-valent silicon and elemental sulfur powder, and is a sphere with a core-shell structure. The inner core is zero-valent silicon, and the outer shell is a silicon-sulfur compound, and the particle size is in the micron range. The sulfurized modified zero-valent silicon composite material provided by the present invention has strong reduction ability, high treatment efficiency for heavy metal ions Cu(II), Cd(II), Pb(II), Zn(II) in wastewater, small dosage, short time consumption, good selectivity, and is applicable to both acidic and alkaline environment treatments, with strong universality. The obtained heavy metal-containing precipitate has good stability, has the value of large-scale industrial application, and has high economic benefits.

Description

Technical Field

[0001] The present invention belongs to the technical field of treatment of wastewater polluted by heavy metals or heavy metal compounds, and particularly relates to a sulfurized modified zero-valent silicon composite material, a preparation method thereof and an application thereof. Background Art

[0002] Industrial wastewater and mine wastewater discharged by human social activities contain a large number of highly toxic, bioaccumulative and carcinogenic harmful substances. According to reports by the World Health Organization, hundreds of millions of people's drinking water worldwide is threatened by severe chemical pollution and hazardous waste pollution, and a relatively typical pollutant among them is heavy metals.

[0003] Relatively common heavy metal ions in wastewater mainly include Cu(II), Cd(II), Pb(II), Zn(II), etc. Harmful heavy metal elements enter the human body through direct drinking, respiratory tract and skin, etc., and mainly remain in organ tissues such as the liver, kidney, brain, etc. When in excess, they cause poisoning to these human organs, and in severe cases, cause functional damage until complete loss. For example, when the copper Cu(II) in the human body is in excess, it will cause gastric ulcers, liver and kidney damage, and even brain damage and death in severe cases. Cadmium Cd(II) is a recognized carcinogenic heavy metal, which can cause lesions in human organs, inhibit the enzyme system, cause symptoms such as diabetes and pneumonia, and even cause death. When the cadmium content in the human body reaches a certain level, it will directly damage the renal tubules, resulting in glucosuria, proteinuria, aminoaciduria, and increasing the excretion of urinary calcium and uric acid, causing renal insufficiency, and ultimately triggering "itai-itai disease". Lead Pb(II) can enter the human body through the digestive tract, respiratory tract and skin, and continuously accumulate in tissues such as nerves, hematopoiesis, digestion, cardiovascular, kidneys and immunity, causing diseases such as peripheral neuritis, anemia, hepatocyte damage, autonomic nervous system dysfunction, lead nephropathy, and reduced immunity. Zinc Zn(II) exceeding a certain amount in the human body will reduce human immunity, and symptoms such as abdominal pain, vomiting, and liver and kidney failure will occur.

[0004] Globally, currently only 20% of wastewater is discharged after treatment. Untreated wastewater brings pollutants into nature to pollute natural water bodies, and at the same time further threatens human health. Traditional alkali neutralization processes consume a large amount of alkali when treating strongly acidic wastewater, and also produce a large amount of precipitation sludge. The further treatment of this alkali precipitation sludge will face many challenges. Therefore, developing a simple, convenient and economical treatment method to reduce the concentration of heavy metal ions in wastewater from the source and purify natural water bodies polluted by heavy metal ions is of great significance.

[0005] Zero-valent silicon has a large specific surface area and a high reduction potential (E H 0(=-0.807 V) has great advantages in the removal of heavy metal ion-polluted water bodies. From the perspective of raw material sources, silicon, as the second most abundant element in the earth's crust, it is worth looking forward to rationally using it to address environmental issues, and in terms of the global abundance of silicon, it will not cause secondary pollution to the environment. However, while zero-valent silicon has high reduction activity, it will also form a low-activity silicon oxide compound on the surface, resulting in the inability to exhibit the reduction activity of the internal zero-valent silicon. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a sulfur-modified zero-valent silicon composite material, its preparation method and application in view of the above deficiencies in the prior art. The sulfur-modified zero-valent silicon composite material has high reduction activity, has a strong selective removal effect on heavy metal ions Cu(II), Cd(II), Pb(II), Zn(II) in wastewater, especially can maintain excellent heavy metal removal ability in acidic solutions, and has strong practicability.

[0007] To solve the above technical problems, the technical solution provided by the present invention is:

[0008] Provide a sulfur-modified zero-valent silicon composite material, which is directly obtained by ball milling zero-valent silicon and elemental sulfur powder, is a sphere with a core-shell structure, the inner core is zero-valent silicon, the outer shell is a silicon-sulfur compound, and the particle size is in the micron range.

[0009] According to the above scheme, the particle size of the zero-valent silicon is in the micron range.

[0010] According to the above scheme, the particle size of the elemental sulfur powder is in the micron range.

[0011] According to the above scheme, the molar ratio of zero-valent silicon to elemental sulfur powder is 1:0.02 - 0.7. Preferably, the molar ratio of zero-valent silicon to elemental sulfur powder is 1:0.3.

[0012] The present invention also includes a preparation method of the above sulfur-modified zero-valent silicon composite material, and the specific steps are as follows:

[0013] 1) Weigh the raw materials according to the ratio and set aside;

[0014] 2) Add zero-valent silicon and elemental sulfur powder into the ball milling tank, and put grinding balls to carry out dry ball milling to obtain the sulfur-modified zero-valent silicon composite material.

[0015] According to the above scheme, the process conditions of step 2) dry ball milling are: using zirconia balls as grinding balls, the diameter of the grinding balls is 15 mm, the ball milling speed is 100 - 600 rpm, pause for 1 - 5 minutes every 5 minutes of ball milling, and change the ball milling direction once, and the effective ball milling time is 0.5 - 2 h.

[0016] The present invention also includes the application of the above-mentioned sulfurized modified zero-valent silicon composite material in water treatment, which is used to remove one or more of heavy metal ions Cu(II), Cd(II), Pb(II), and Zn(II) in water bodies.

[0017] According to the above solution, the dosage of the sulfurized modified zero-valent silicon composite material in the water body is 0.1 - 2.0 g / L. The sulfurized modified zero-valent silicon composite material has a wide working pH value range. When the pH value in the water body is alkaline, heavy metal ions will form alkali precipitates. When the pH value of the water body is 1 - 5, the removal rate of heavy metal ions only decreases slightly. The sulfurized modified zero-valent silicon composite material has better removal effects on heavy metal ions under both acidic and alkaline conditions of the water body.

[0018] In the present invention, zero-valent silicon and elemental sulfur powder are ball-milled together. During the ball-milling process, the silicon oxide compounds with poor surface activity on the surface of zero-valent silicon are peeled off and a fresh zero-valent silicon surface is exposed. Then, an oxidation-reduction reaction occurs between the zero-valent silicon with strong reducing properties and the elemental sulfur powder, and silicon sulfide compounds are formed on the surface of zero-valent silicon, forming a core-shell structure with a silicon sulfide compound shell and a zero-valent silicon core. The removal mechanism of heavy metal ions by this sulfurized modified zero-valent silicon composite material is mainly that sulfide ions on the surface of the sample form heavy metal sulfide precipitates with heavy metal ions. Compared with untreated zero-valent silicon, the removal effect on heavy metal ions is better.

[0019] The beneficial effects of the present invention are as follows: 1. The sulfurized modified zero-valent silicon composite material provided by the present invention has strong reduction ability, high treatment efficiency for heavy metal ions Cu(II), Cd(II), Pb(II), and Zn(II) in wastewater, small dosage,

[0020] short time consumption, good selectivity, and is applicable to treatment in both acidic and alkaline environments, with strong universality. The obtained heavy metal-containing precipitate has good stability, has large-scale industrial application value, and high economic benefits. 2. The raw materials of the present invention are widely sourced. For example, zero-valent silicon can be selected from zero-valent silicon recovered from waste battery plates, with low cost. The preparation process does not produce waste, and it is green and environmentally friendly. Description of the Drawings

[0021] Figure 1 It is a comparison chart of the removal rate of Cu in the solution and the influence of pH value by the sulfurized modified zero-valent silicon composite materials with different silicon-sulfur ratios prepared in Examples 1 - 6 of the present invention; 2+ Removal rate and pH value influence comparison chart;

[0022] Figure 2 It is a comparison chart of the removal rate of Cu in the solution and the influence of pH value under different dosages of the sulfurized modified zero-valent silicon composite material prepared in Example 4; 2+ Removal rate and pH value influence comparison chart;

[0023] Figure 3Comparison chart of the effects of different dosages of the sulfurized modified zero-valent silicon composite material prepared in Example 4 on the removal rate of Cd and pH in the solution 2+ in the solution

[0024] Figure 4 Comparison chart of the effects of different dosages of the sulfurized modified zero-valent silicon composite material prepared in Example 4 on the removal rate of Pb and pH in the solution 2+ in the solution

[0025] Figure 5 Comparison chart of the effects of different dosages of the sulfurized modified zero-valent silicon composite material prepared in Example 4 on the removal rate of Zn and pH in the solution 2+ in the solution

[0026] Figure 6 Comparison chart of the effects of the sulfurized modified zero-valent silicon composite material prepared in Example 4 at dosages of 0.5 g / L and 0.7 g / L on the removal rate of Cu and pH in solutions with different initial pH values 2+ in the solution

[0027] Figure 7 XRD patterns of the sulfurized modified zero-valent silicon composite material samples prepared in Example 3 and Example 5 and the filter residue samples after removing copper ions

[0028] Figure 8 XPS spectra of the composite material samples prepared in Example 4 and the filter residue samples after removing copper ions at different dosages

[0029] Figure 9 Comparison chart of the effects of different dosages of the sulfurized modified zero-valent silicon composite material prepared in Example 4 on the removal rate of Mn and pH value in the solution 2+ in the solution

[0030] Figure 10 Comparison chart of the effects of different dosages of the sulfurized modified zero-valent silicon composite material prepared in Example 4 on the removal rates of Cu and Mn in the Cu and Mn mixed solution and pH value 2+ and Mn 2+ in the Cu 2+ and Mn 2+ in the solution Specific implementation manners

[0031] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] Examples 1 - 6

[0033] A sulfurized modified zero-valent silicon composite material, and its preparation method specifically comprises the following steps:

[0034] 1) Weigh 6 groups of zero-valent silicon (micrometer-sized) and elemental sulfur powder (micrometer-sized). The total mass of the two in each group is 3 g, and the molar ratios of zero-valent silicon to elemental sulfur powder are 1:0.02, 1:0.08, 1:0.1, 1:0.3, 1:0.5, and 1:0.7 respectively. At different silicon-sulfur molar ratios, the mass details of the two raw materials are shown in Table 1 below:

[0035] Table 1

[0036] Sample Silicon-sulfur molar ratio Mass of zero-valent silicon (g) Mass of elemental sulfur powder (g) Total mass (g) Example 1 1：0.02 2.9332 0.0668 3 Example 2 1：0.08 2.7480 0.2520 3 Example 3 1：0.1 2.6916 0.3084 3 Example 4 1：0.3 2.2333 0.7667 3 Example 5 1：0.5 1.9079 1.0921 3 Example 6 1：0.7 1.6590 1.3410 3

[0037] 2) Add each group of zero-valent silicon and elemental sulfur powder into a zirconia ball-milling jar with an internal volume of 45 cm 3 , and put 7 zirconia balls with a diameter of 15 mm. Set the ball-milling speed at 600 rpm. Pause for 5 min every 5 min of ball milling, and change the ball-milling direction once. The effective ball-milling time is 2 h. After ball milling, 6 kinds of sulfurized modified zero-valent silicon composites are obtained and stored in a dry and sealed bag under normal temperature and pressure.

[0038] Example 7

[0039] Test the effect of the sulfurized modified zero-valent silicon composites with different silicon-sulfur ratios prepared in Examples 1-6 on removing heavy metal Cu(II).

[0040] At room temperature of 20 °C, take 6 250-mL beakers, and add 100 mL of Cu(II) solution with a concentration of 100 mg / L (obtained by dissolving copper sulfate pentahydrate in water) to each beaker. Control its pH value at 5.0, measure the copper ion concentration and pH value of the solution before the reaction, and then add 0.05 g of the sulfurized modified zero-valent silicon composites prepared by ball milling at different silicon-sulfur ratios in Examples 1-6 to the 6 beakers respectively (the sample dosage is 0.5 g / L). Stir on a constant-temperature magnetic stirrer for 120 min. After the reaction, measure the copper ion concentration and pH value of the supernatant, and calculate the copper ion removal rate.

[0041] The results are as Figure 1 shown. The sulfurized modified zero-valent silicon composites with different silicon-sulfur ratios have different effects on removing copper ions. As the relative content of elemental sulfur powder in the raw materials increases, the removal effect of the sample on copper ions first increases and then decreases, and reaches the best when the molar ratio of silicon to sulfur elements is 1:0.3. At the same time, the pH of the supernatant after the reaction also reaches the lowest at this molar ratio, which is due to the generation of sulfuric acid. The relevant equation is: SiS2 + 2CuSO4 + 2H2O == 2CuS + SiO2 + 2H2SO4.

[0042] Example 8

[0043] Test the effect of the composite material prepared in Example 4 (molar ratio of zero-valent silicon: elemental sulfur powder = 1:0.3) with different dosages on removing heavy metal Cu(II).

[0044] At room temperature of 20 °C, take 10 250 mL beakers, and add 100 mL of Cu(II) solution with a concentration of 100 mg / L to each beaker (the preparation method is the same as that in Example 7). Control its pH to be 5.0, measure the copper ion concentration and pH value of the solution before the reaction. Add 0.01 g, 0.02 g, 0.03 g, 0.04 g, 0.05 g, 0.06 g, 0.07 g, 0.08 g, 0.09 g, and 0.10 g of the sulfur-modified zero-valent silicon composite material prepared by ball milling to the 10 beakers respectively (the sample dosage is 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1.0 g / L). Stir on a constant temperature magnetic stirrer for 120 min. After the reaction ends, measure the copper ion concentration and pH value of the supernatant in each beaker, and calculate the copper ion removal rate at different dosages.

[0045] The results are as Figure 2 shown. The removal effect of the sulfur-modified zero-valent silicon composite material on copper ions is different at different dosages. As the sample dosage increases, the removal effect of the sample on copper ions first increases and then decreases, and reaches the best at a dosage of 0.8 g / L. At the same time, the pH of the supernatant after the reaction continues to decrease. The main mechanism of the reaction in the liquid phase is the formation of copper sulfide precipitation. The addition of excessive samples will generate polysulfides that redissolve, resulting in a decrease in the copper ion removal rate.

[0046] Adding the raw material zero-valent silicon in Example 1 directly to the Cu(II) solution with a concentration of 100 mg / L (the preparation method is the same as that in Example 7) at a dosage of 0.8 g / L did not achieve the effect of removing copper ions. This is because the strong reducibility of zero-valent silicon leads to the formation of a silicon oxide compound with low activity and poor electron conduction performance on the outer layer, which prevents the reaction between the internal zero-valent silicon and heavy metal ions.

[0047] Add 3 g of the raw material zero-valent silicon in Example 1 to a zirconia ball milling tank with an internal volume of 45 cm 3 and put 7 zirconia balls with a diameter of 15 mm. Set the ball milling speed to 600 rpm. Pause for 5 min every 5 min of ball milling and change the ball milling direction once. The effective ball milling time is 2 h. After ball milling, add it directly to the Cu(II) solution with a concentration of 100 mg / L (the preparation method is the same as that in Example 7) at a dosage of 0.8 g / L, and the effect of removing copper ions is also very poor. The main reason is that even if the silicon oxide compound on the surface is peeled off by ball milling, the exposed fresh zero-valent silicon surface immediately forms a silicon oxide compound shell when it contacts the oxygen in the air, resulting in the inability of zero-valent silicon to play a reducing role.

[0048] Example 9

[0049] Test the effect of removing heavy metal Cd(II) at different dosages of the composite material prepared in Test Example 4 (molar ratio of zero-valent silicon to elemental sulfur powder = 1:0.3).

[0050] At room temperature of 20 °C, take 10 250 mL beakers, add 100 mL of Cd(II) solution with a concentration of 100 mg / L (obtained by dissolving cadmium sulfate in water) to each beaker, control its pH to 5.0, and measure the cadmium ion concentration and pH value of the solution before the reaction. Add 0.01 g, 0.02 g, 0.03 g, 0.04 g, 0.05 g, 0.06 g, 0.07 g, 0.08 g, 0.09 g, 0.10 g of the sulfurized modified zero-valent silicon composite material prepared by ball milling (sample dosage is 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1.0 g / L) to the 10 beakers respectively, stir on a constant temperature magnetic stirrer for 120 min, measure the cadmium ion concentration and pH value of the supernatant in the 10 beakers after the reaction, and calculate the cadmium ion removal rate.

[0051] The results are as Figure 3 shown. The effect of removing cadmium ions by the sulfurized modified zero-valent silicon composite material is different at different dosages. As the sample dosage increases, the effect of the sample on removing cadmium ions first increases and then decreases, and reaches the best at a dosage of 0.7 g / L. At the same time, the pH of the supernatant after the reaction continues to decrease. The main mechanism of the reaction in the liquid phase is the formation of cadmium sulfide precipitation. The addition of more samples will generate polysulfides to redissolve, resulting in a decrease in the cadmium ion removal rate.

[0052] Example 10

[0053] Test the effect of removing heavy metal Pb(II) at different dosages of the composite material prepared in Test Example 4 (molar ratio of zero-valent silicon to elemental sulfur powder = 1:0.3).

[0054] At room temperature of 20 °C, take 20 250 mL beakers, and add 100 mL of Pb(II) solution with a concentration of 100 mg / L (obtained by dissolving lead nitrate in water) to each beaker. Control its pH to 5.0, and measure the copper ion concentration and pH value of the solution before the reaction. Add 0.01 g, 0.02 g, 0.03 g, 0.04 g, 0.05 g, 0.06 g, 0.07 g, 0.08 g, 0.09 g, 0.10 g, 0.11 g, 0.12 g, 0.13 g, 0.14 g, 0.15 g, 0.16 g, 0.17 g, 0.18 g, 0.19 g, 0.20 g of the sulfur-modified zero-valent silicon composite material prepared by ball milling (the sample dosage is 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1.0 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L, 1.5 g / L, 1.6 g / L, 1.7 g / L, 1.8 g / L, 1.9 g / L, 2.0 g / L) to 10 beakers respectively, stir on a constant-temperature magnetic stirrer for 120 min. After the reaction ends, measure the lead ion concentration and pH value of the supernatant in each beaker, and calculate the lead ion removal rate.

[0055] The results are as Figure 4 shown. The effects of removing lead ions by the sulfur-modified zero-valent silicon composite material with different dosages are different. As the sample dosage increases, the effect of the sample on removing lead ions first increases, then remains unchanged and stabilizes at a relatively high removal level, reaching the best at a dosage of 1.0 g / L. At the same time, the pH of the supernatant after the reaction gradually decreases slowly. The main mechanism of the reaction in the liquid phase is the precipitation of lead sulfide.

[0056] Example 11

[0057] Test the effect of removing heavy metal Zn(II) by the composite material prepared in Test Example 4 (molar ratio of zero-valent silicon: elemental sulfur powder = 1:0.3) with different dosages.

[0058] At room temperature of 20 °C, 20 250 mL beakers were taken. 100 mL of Zn(II) solution with a concentration of 100 mg / L (obtained by dissolving zinc sulfate in water) was added to each beaker, and its pH was controlled to be 5.0. The zinc ion concentration and pH value of the solution before the reaction were measured. 0.01 g, 0.02 g, 0.03 g, 0.04 g, 0.05 g, 0.06 g, 0.07 g, 0.08 g, 0.09 g, 0.10 g, 0.11 g, 0.12 g, 0.13 g, 0.14 g, 0.15 g, 0.16 g, 0.17 g, 0.18 g, 0.19 g, 0.20 g of the sulfur-modified zero-valent silicon composite prepared by ball milling (the sample dosage was 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1.0 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L, 1.5 g / L, 1.6 g / L, 1.7 g / L, 1.8 g / L, 1.9 g / L, 2.0 g / L) were added to 10 beakers respectively. They were stirred on a constant-temperature magnetic stirrer for 120 min. After the reaction ended, the zinc ion concentration and pH value of the supernatant in each beaker were measured, and the zinc ion removal rate was calculated.

[0059] The results are as Figure 5 shown. The effects of the sulfur-modified zero-valent silicon composite on the removal of zinc ions were different at different dosages. As the sample dosage increased, the removal effect of the sample on zinc ions first increased, then remained unchanged and stabilized at a relatively high removal level. The best effect was achieved at a dosage of 1.1 g / L. At the same time, the pH value of the supernatant after the reaction gradually decreased slowly. The main mechanism of the reaction in the liquid phase was the formation of zinc sulfide precipitation.

[0060] Example 12

[0061] The effect of the composite material prepared in Test Example 4 (molar ratio of zero-valent silicon: elemental sulfur powder = 1:0.3) on removing heavy metal Cu(II) in solutions with different initial pH values was tested.

[0062] At room temperature of 20 °C, take 10 250 mL beakers, and add 100 mL of Cu(II) solution with a concentration of 100 mg / L to each beaker (the preparation method is the same as in Example 7). Use sulfuric acid solution and sodium hydroxide solution to adjust the pH values of the aqueous phases in 5 of the beakers to 1, 2, 3, 4, and 5 respectively, and add 0.05 g of the sulfur-modified zero-valent silicon composite material sample prepared in Example 4 (the dosing amount is 0.5 g / L) to these 5 beakers. Stir on a constant-temperature magnetic stirrer for 120 min. After the reaction, measure the copper ion concentration and pH value of the supernatant in these 5 beakers, and calculate the copper ion removal rate. Use sulfuric acid solution and sodium hydroxide solution to adjust the pH values of the aqueous phases in the other 5 beakers to 1, 2, 3, 4, and 5 respectively, and add 0.07 g of the sulfur-modified zero-valent silicon composite material sample prepared in Example 4 (the dosing amount is the optimal dosing amount of 0.7 g / L). Stir on a constant-temperature magnetic stirrer for 120 min. After the reaction, measure the copper ion concentration and pH value of the supernatant in these 5 beakers, and calculate the copper ion removal rate.

[0063] The results are as Figure 6 shown. It can be seen that under the condition of the same dosing amount, the change of pH value has little effect on the copper ion removal rate, and a good removal effect can also be achieved under strong acidic conditions (pH = 1).

[0064] Example 13

[0065] Test the effect of the composite materials (molar ratio of zero-valent silicon: elemental sulfur powder = 1:0.1 / 0.5) prepared in Example 3 and Example 5 on removing heavy metal Cu(II).

[0066] At room temperature of 20 °C, take 2 250 mL beakers, and add 100 mL of Cu(II) solution with a concentration of 100 mg / L to each beaker (the preparation method is the same as in Example 7). Add 0.08 g of the sulfur-modified zero-valent silicon composite material samples with different silicon-sulfur molar ratios prepared in Example 3 and Example 5 (the dosing amount is 0.8 g / L) to the two beakers respectively. Stir on a constant-temperature magnetic stirrer for 120 min, filter out the filter residue, and air-dry it at room temperature for 24 h.

[0067] Perform XRD pattern analysis on the sulfur-modified zero-valent silicon composite material samples prepared in Example 3 and Example 5 and the filter residue samples after removing copper ions. The results are as Figure 7 shown. In the figure, 1Si+0.1S represents the composite material prepared in Example 3, 1Si+0.1S(Cu 2+ ) represents the filter residue sample of the composite material prepared in Example 3 after removing copper ions, 1Si+0.5S represents the composite material prepared in Example 5, 1Si+0.5S(Cu 2+) It represents the filter residue sample after the composite material prepared in Example 5 removes copper ions. It can be seen that diffraction peaks of silicon and sulfur still exist in the composite material samples prepared in Example 3 and Example 5, indicating that there is still some zero-valent silicon and elemental sulfur powder that did not participate in the reaction. Diffraction peaks of copper sulfide appear in the filter residue, indicating that the formation of heavy metal sulfide precipitation is the main mechanism for the removal of copper ions.

[0068] Example 14

[0069] Test the effect of the composite material (molar ratio of zero-valent silicon: elemental sulfur powder = 1:0.3) prepared in Example 4 on removing heavy metal Cu(II).

[0070] The room temperature is 20°C. Take 2 250 mL beakers, and add 100 mL of Cu(II) solution with a concentration of 100 mg / L (the preparation method is the same as that in Example 7) to the beakers respectively. Add 0.07 g and 0.10 g of the composite material sample prepared in Example 4 to the two beakers respectively (ensure that the dosage is 0.7 g / L and 1.0 g / L), stir for 120 min on a constant temperature magnetic stirrer, filter out the filter residue, and air-dry it at room temperature for 24 h.

[0071] Perform XPS spectrum (S2p) analysis on the composite material sample prepared in Example 4 and the filter residue samples after removing copper ions at different dosages. The results are as Figure 8 shown. The valence states of sulfur in the composite material sample prepared in Example 4 are mainly 0 valence and +6 valence. Sulfur in the negative valence state is in an unstable state and is difficult to detect. It is worth noting that the valence state of sulfur in the filter residue shows a significant -2 valence, which further verifies that the precipitation of sulfide is the main mechanism for the removal of heavy metal ions.

[0072] Example 15

[0073] Test the effect of the composite material (molar ratio of zero-valent silicon: elemental sulfur powder = 1:0.3) prepared in Example 4 at different dosages on removing heavy metal Mn(II).

[0074] At room temperature of 20 °C, take 10 250 mL beakers, and add 100 mL of Mn(II) solution with a concentration of 100 mg / L (obtained by dissolving manganese sulfate in water) to each beaker. Control its pH to 5.0, measure the copper ion concentration and pH value of the solution before the reaction. Add 0.01 g, 0.02 g, 0.03 g, 0.04 g, 0.05 g, 0.06 g, 0.07 g, 0.08 g, 0.09 g, 0.10 g of the sulfur-modified zero-valent silicon composite material prepared by ball milling (the sample dosage is 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1.0 g / L) to the 10 beakers respectively, stir on a constant temperature magnetic stirrer for 120 min. After the reaction, measure the manganese ion concentration and pH value of the supernatant in each beaker, and calculate the manganese ion removal rate at different dosages.

[0075] The results are as Figure 9 shown. It can be seen that increasing the sample dosage does not reduce the manganese ion concentration in the solution, indicating that the composite material prepared in Example 4 has 2+ almost no removal effect on Mn in the solution.

[0076] Replace the Mn(II) solution in this example with Ni(II) (obtained by dissolving nickel sulfate in water) for the same test. The results show that the composite material prepared in Example 4 has 2+ no removal effect on Ni in the solution.

[0077] Example 16

[0078] Test the removal effect of the composite material (molar ratio of zero-valent silicon: elemental sulfur powder = 1:0.3) prepared in Example 4 at different dosages on the 2+ Cu 2+ and Mn

[0079] mixed solution. At room temperature of 20 °C, take 10 250 mL beakers, and add 100 mL of 2+ Cu 2+ and Mn 2+ mixed solution (obtained by dissolving copper sulfate and manganese sulfate in water, with the 2+At a concentration of 100 mg / L, control its pH to 5.0, measure the copper ion concentration and pH value of the solution before the reaction. Add 0.01 g, 0.02 g, 0.03 g, 0.04 g, 0.05 g, 0.06 g, 0.07 g, 0.08 g, 0.09 g, and 0.10 g of the sulfur-modified zero-valent silicon composite prepared by ball milling (the sample dosage is 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1.0 g / L) to 10 beakers respectively, stir on a constant temperature magnetic stirrer for 120 min. After the reaction, measure the copper ion concentration, manganese ion concentration, and pH value of the supernatant in each beaker, and calculate the removal rates of copper ions and manganese ions at different dosages.

[0080] The results are as Figure 10 shown. It can be seen that increasing the sample dosage does not reduce the manganese ion concentration in the solution, while the copper ion concentration decreases significantly, indicating that the composite material prepared in Example 4 has a certain selectivity for the removal of metal ions in the solution.

Claims

1. A sulfur-modified zero-valent silicon composite material, characterized in that, It is directly obtained by ball milling zero-valent silicon and elemental sulfur powder. The molar ratio of zero-valent silicon to elemental sulfur powder is 1:0.02 - 0.

7. It is a sphere with a core-shell structure, with the inner core being zero-valent silicon and the outer shell being a silicon-sulfur compound, and the particle size is in the micron range; The ball milling process conditions are as follows: Using zirconia balls as grinding balls, the diameter of the grinding balls is 15 mm, the ball milling speed is 100 - 600 rpm, pause for 1 - 5 minutes every 5 minutes of ball milling, and change the ball milling direction once. The effective ball milling time is 0.5 - 2 h.

2. The sulfurized modified zero-valent silicon composite material according to claim 1, wherein The particle size of the zero-valent silicon is in the micron range.

3. The sulfurized modified zero-valent silicon composite material according to claim 1, characterized in that The particle size of the elemental sulfur powder is in the micron range.

4. The sulfurized modified zero-valent silicon composite material according to claim 1, wherein The molar ratio of the zero-valent silicon to the elemental sulfur powder is 1:0.

3.

5. A method for preparing the sulfur-modified zero-valent silicon composite material according to any one of claims 1-4, characterized in that, The specific steps are as follows: 1) Weigh the raw materials in proportion and set aside; 2) Add zero-valent silicon and elemental sulfur powder into the ball milling tank, and put in the grinding balls for dry ball milling to obtain the sulfur-modified zero-valent silicon composite material. The dry ball milling process conditions are as follows: Using zirconia balls as grinding balls, the diameter of the grinding balls is 15 mm, the ball milling speed is 100 - 600 rpm, pause for 1 - 5 minutes every 5 minutes of ball milling, and change the ball milling direction once. The effective ball milling time is 0.5 - 2 h.

6. Use of the sulfurized modified zero-valent silicon composite material according to any one of claims 1-4 in water treatment, characterized in that, It is used to remove one or more of the heavy metal ions Cu(II), Cd(II), Pb(II), Zn(II) in water.

7. Use of the sulfur-modified zero-valent silicon composite material according to claim 6 in water treatment, characterized in that, The dosage of the sulfur-modified zero-valent silicon composite material in water is 0.1 - 2.0 g / L.

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