A bismuth-containing complex, its preparation method, and its application in chloride ion elution.
By mixing bismuth oxide complex doped with semiconductor elements with alkaline substances and oxidants under light conditions, the problems of high cost and large alkali consumption in existing dechlorination technologies are solved, and the effect of high-concentration chloride ion wastewater is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGSU UNIV OF TECH
- Filing Date
- 2023-11-16
- Publication Date
- 2026-05-26
AI Technical Summary
Existing chemical precipitation methods for dechlorination are costly and consume large amounts of alkali during regeneration, making them difficult to efficiently treat wastewater with high concentrations of chloride ions.
A bismuth-containing composite was prepared by doping semiconductor elements such as titanium, nickel, copper, iron, cobalt, carbon, and nitrogen. The bismuth oxide composite was then mixed with alkaline substances and oxidants under light conditions to carry out dechlorination reaction and elution, thereby reducing the stability of the Bi-O covalent bond, promoting the dechlorination reaction, and improving the regeneration efficiency of bismuth oxide.
It reduced alkali consumption, improved dechlorination efficiency and recycling efficiency of bismuth-containing complexes, and reduced regeneration costs.
Smart Images
Figure CN117361717B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a bismuth-containing complex, its preparation method, and its application in chloride ion elution, belonging to the field of wastewater treatment technology. Background Technology
[0002] Chloride ions are widely available and pose significant hazards. Wastewater containing high concentrations of chloride ions can corrode pipelines, equipment, and reinforced concrete, threatening safe production and reducing the lifespan of buildings. High concentrations of chloride ions in wastewater can also affect agricultural irrigation and have toxic effects on aquatic organisms such as fish.
[0003] Currently, common methods for chloride ion removal include electrolysis, evaporation and concentration, ion exchange, and precipitation. Among the published chloride removal methods, chemical precipitation has been widely reported due to its wide availability of raw materials, high chloride removal efficiency, and stable performance. Bismuth oxide chloride removal within chemical precipitation has received considerable attention in recent years as a stable and efficient method. However, this method requires a large amount of bismuth, necessitating a solution to the problem of excessively high chloride removal costs. Researchers have proposed that under certain conditions, bismuth oxychloride in the chloride removal product can be converted into bismuth oxide, and the regenerated chloride removal agent still possesses good chloride removal performance. Wu Yue et al. (Research on Dry Regeneration of Bismuth Oxide from Wastewater Chlorination Products, Journal of Jiangsu University of Technology, 2021) explored the effect of dry regeneration in removing chloride ions, requiring a temperature of 800℃ and generating numerous byproducts. Wu Wenhua et al. (Research on the Regeneration and Recycling of Bismuth Oxide Chloride in Zinc Electrolyte Dechlorination Slag, China Nonferrous Metallurgy, 2015) explored wet regeneration, which uses sodium hydroxide solution to remove chloride ions from bismuth oxychloride and regenerate bismuth oxide. However, this method consumes a large amount of sodium hydroxide, resulting in high cost. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a bismuth-containing complex, its preparation method, and its application in chloride ion elution. This bismuth-containing complex can promote the dechlorination reaction and, when applied, can reduce alkali consumption and save regeneration costs.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A bismuth-containing composite comprising bismuth oxide and a dopant element, wherein the dopant element is one or more of titanium, nickel, copper, iron, cobalt, carbon, and nitrogen.
[0007] The above-mentioned method for preparing the bismuth-containing composite involves mixing bismuth nitrate with one or more of titanium dioxide, nickel nitrate, copper nitrate, iron nitrate, cobalt nitrate, and melamine, and calcining the mixture at 300-700℃ for 1.5-2.5 h to obtain a bismuth-containing composite with elemental doping.
[0008] Furthermore, the bismuth oxide content in the bismuth-containing complex is ≥98%.
[0009] The application of the above-mentioned bismuth-containing complex in chloride ion elution includes the following steps:
[0010] The bismuth-containing complex was added to the chlorine-containing wastewater for dechlorination. After the dechlorination was completed, the wastewater was filtered and dried to obtain a dechlorination product containing bismuth oxychloride.
[0011] An elution solution is prepared by mixing alkaline substances, oxidizing agents and water. The dechlorinated product is then added to the elution solution, eluted by light, and then filtered, washed and dried to obtain a regenerated bismuth-containing complex.
[0012] Regenerated bismuth-containing complexes are used for the cyclical removal of chlorine from chlorine-containing wastewater.
[0013] Preferably, the pH of the chlorine-containing wastewater is 0.1 to 5, and the chloride ion content is 100 to 30,000 mg / L.
[0014] Preferably, the solid-liquid mass ratio of the bismuth-containing complex to the chlorine-containing wastewater is 1:(20-100).
[0015] Preferably, the solid-liquid mass ratio of the dechlorination product to the elution solution is 1:(10-50), and the mass ratio of the dechlorination product to the alkaline substances and oxidant in the elution solution is 1:(0.05-0.1)(0.01-0.05).
[0016] Preferably, the alkaline substance is one or more of the following: calcium oxide, calcium hydroxide, sodium hydroxide, potassium hydroxide, lithium hydroxide, carbide slag, iron hydroxide, magnesium hydroxide, zinc hydroxide, ammonia, quaternary ammonium alkali, and guanidine compounds.
[0017] Preferably, the oxidant is one or more selected from hydrogen peroxide, sodium peroxide, calcium peroxide, magnesium peroxide, potassium peroxide, sodium hypochlorite, sodium chlorite, sodium perchlorate, peracetic acid, and potassium permanganate.
[0018] Preferably, the dechlorination reaction is carried out under stirring, and the dechlorination time is 0.5-1.5 hours.
[0019] Preferably, the light elution time is 10-120 minutes, and the light source is one or more of ultraviolet light, visible light, and infrared light.
[0020] The beneficial effects of this invention are as follows:
[0021] 1. Semiconductor elements are selected as dopants to be introduced into bismuth-containing complexes in order to reduce the stability of Bi-O covalent bonds in the sample, making them more susceptible to breakage under the attack of hydrogen ions, leading to structural collapse, thereby releasing more bismuth ions and promoting the dechlorination reaction.
[0022] 2. Semiconductor elements are selected as dopants and introduced into the bismuth-containing composite. After the bismuth-containing composite participates in the dechlorination reaction, the dechlorination products easily form heterojunctions under light excitation during the elution process, causing electrons to transfer to the introduced semiconductor and form electron-hole pairs. The remaining holes on bismuth oxychloride will undergo photocorrosion, promoting the conversion of bismuth oxychloride to bismuth oxide. In other words, the introduction of semiconductor elements promotes the elution of chloride ions, thereby increasing the bismuth oxide content in the regenerated bismuth-containing composite dechlorinating agent, which is conducive to recycling and can improve the subsequent dechlorination efficiency.
[0023] 3. The bismuth-containing composite material provided by this invention can be used to efficiently treat chloride ions in wastewater and obtain a dechlorination product containing bismuth oxychloride. During the regeneration process, alkaline substances, oxidants, and light radiation are introduced, which can improve the elution efficiency of chloride ions in bismuth oxychloride while reducing alkali consumption and saving regeneration costs. Attached Figure Description
[0024] Figure 1 Here is a SEM image of the bismuth-containing composite prepared in Example 2;
[0025] Figure 2 The image shows the EDS spectrum of the bismuth-containing complex prepared in Example 2. Detailed Implementation
[0026] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0027] Example 1
[0028] Bismuth nitrate, ferric nitrate, and melamine were mixed and calcined at 600°C for 2 hours to obtain a bismuth-containing composite containing iron-doped bismuth oxide and carbon nitride. The mass fraction of iron was 0.2%, the mass fraction of carbon nitride was 1.5%, and the mass fraction of bismuth oxide was 98.3%.
[0029] A bismuth-containing complex was used to treat chlorinated wastewater with a chloride ion concentration of 1352.55 mg / L and a pH of 1.5. The solid-liquid mass ratio of the bismuth-containing complex to the wastewater was 1:100. After one hour of dechlorination reaction, stirring was stopped, and the dechlorination efficiency was measured to be 95.6%. The resulting product was filtered and dried to obtain a dechlorinated product containing bismuth oxychloride, iron oxide, and carbon nitride. The mass fractions of bismuth oxychloride, iron oxide, and carbon nitride were 89.5%, 0.25%, 1.5%, and 8.9% of the remaining bismuth oxide.
[0030] The dechlorination product was added to an elution solution containing an alkali, an oxidant, and water at a solid-liquid mass ratio of 1:20. The alkali was calcium oxide, with a dechlorination product to alkali mass ratio of 1:0.1; the oxidant was calcium peroxide, with a dechlorination product to oxidant mass ratio of 1:0.05. The mixture was irradiated with ultraviolet light at room temperature for 60 minutes. The eluted product was filtered, and the chloride ion concentration in the filtrate was measured, yielding an elution efficiency of 80%. The remaining solid product was dried to obtain a regenerated bismuth-containing composite dechlorinating agent, mainly containing bismuth oxide, iron oxide, and carbon nitride, with a bismuth oxide mass fraction exceeding 95%.
[0031] The regenerated bismuth-containing composite dechlorinating agent was used to treat chlorinated wastewater with a chloride ion concentration of 1352.55 mg / L and a pH of 1.5. After reacting for 1 hour at a solid-liquid mass ratio of 1:100, the dechlorination efficiency was measured to be 94.4%. The resulting dechlorinated product was then used in the same type of chlorinated wastewater after elution and other steps, with the operating conditions remaining unchanged.
[0032] After multiple cycles, the dechlorination efficiency of the obtained bismuth-containing complex is shown in the table below.
[0033] Loop count Dechlorination efficiency 1 time 95.6％ 2 times 94.4％ 3 times 88.8％ 4 times 87.5％ 5 times 85.3％ 6 times 86.9％
[0034] Example 2
[0035] A bismuth-containing composite containing iron and titanium-doped bismuth oxide was obtained by calcining a mixture of bismuth nitrate, ferric nitrate, and titanium dioxide at 600°C for 2 hours. The mass fraction of iron was 1%, the mass fraction of titanium was 0.5%, and the mass fraction of bismuth oxide was 98.5%. Figure 1 , 2 The images shown are SEM images and EDS spectra of the prepared bismuth-containing composites. Figure 1 It can be seen that the bismuth-containing complex contains irregular blocky structures, with small particles attached to these irregular blocks; from Figure 2 It can be seen that bismuth (Bi) is concentrated in irregular blocks, and there are also small amounts of titanium (Ti) and iron (Fe) in the structure.
[0036] A bismuth-containing complex was used to treat chlorinated wastewater with a chloride ion concentration of 3283.75 mg / L and a pH of 1. The solid-liquid mass ratio of the bismuth-containing complex to the wastewater was 1:50. After one hour of dechlorination reaction, stirring was stopped, and the dechlorination efficiency was measured to be 83.9%. The resulting product was filtered and dried to obtain a dechlorinated product containing bismuth oxychloride, iron oxide, and titanium dioxide. The mass fractions of bismuth oxychloride were 90.4%, iron oxide 1.8%, and titanium dioxide 0.71%, with a residual bismuth oxide mass fraction of 7.1%.
[0037] The dechlorination product was added to an elution solution containing an alkali, an oxidant, and water at a solid-liquid mass ratio of 1:40. The alkali was potassium hydroxide, with a dechlorination product to alkali mass ratio of 1:0.05; the oxidant was sodium peroxide, with a dechlorination product to oxidant mass ratio of 1:0.01. The reaction was carried out at room temperature under infrared light for 60 minutes. The eluted product was filtered, and the chloride ion concentration in the filtrate was measured, yielding an elution efficiency of 83%. The remaining solid product was dried to obtain a regenerated bismuth-containing composite dechlorinating agent, mainly containing bismuth oxide, iron oxide, and titanium dioxide, with a bismuth oxide mass fraction exceeding 94%.
[0038] The regenerated bismuth-containing composite dechlorinating agent was used to treat chlorinated wastewater with a chloride ion concentration of 3283.75 mg / L and a pH of 1. After reacting for 1 hour at a solid-liquid mass ratio of 1:50, the dechlorination efficiency was measured to be 78.6%. The resulting dechlorinated product was then used in the same type of chlorinated wastewater after elution and other steps, with the operating conditions remaining unchanged.
[0039] After multiple cycles, the dechlorination efficiency of the obtained bismuth-containing complex is shown in the table below.
[0040] Loop count Dechlorination efficiency 1 time 83.9％ 2 times 78.6％ 3 times 78.5％ 4 times 86.9％ 5 times 86.2％ 6 times 78.4％ 7 times 78.1％
[0041] Example 3
[0042] A bismuth-containing composite containing copper and titanium-doped bismuth oxide was obtained by calcining a mixture of bismuth nitrate, copper nitrate, and titanium dioxide at 500°C for 2 hours. The mass fraction of copper was 1%, the mass fraction of titanium was 0.6%, and the mass fraction of bismuth oxide was 98.4%.
[0043] A bismuth-containing complex was used to treat chlorinated wastewater with a chloride ion concentration of 5456.35 mg / L and a pH of 0.8. The solid-liquid mass ratio of the bismuth-containing complex to the wastewater was 1:30. After one hour of dechlorination reaction, stirring was stopped, and the dechlorination efficiency was measured to be 88.6%. The resulting product was filtered and dried to obtain a dechlorinated product containing bismuth oxychloride, cuprous oxide, and titanium dioxide. The mass fractions of bismuth oxychloride were 82.7%, cuprous oxide 0.9%, and titanium dioxide 0.7%, with a residual bismuth oxide mass fraction of 15.6%.
[0044] The dechlorination product was added to an elution solution containing an alkali, an oxidant, and water at a solid-liquid mass ratio of 1:30. The alkali was lithium hydroxide, with a dechlorination product to alkali mass ratio of 1:0.05; the oxidant was sodium peroxide, with a dechlorination product to oxidant mass ratio of 1:0.05. The reaction was carried out at room temperature under visible light for 60 minutes. The eluted product was filtered, and the chloride ion concentration in the filtrate was measured, yielding an elution efficiency of 81%. The remaining solid product was dried to obtain a regenerated bismuth-containing composite dechlorinating agent, mainly containing bismuth oxide, copper oxide, and nickel oxide, with a bismuth oxide mass fraction exceeding 93%.
[0045] The regenerated bismuth-containing composite dechlorinating agent was used to treat chlorinated wastewater with a chloride ion concentration of 5456.35 mg / L and a pH of 0.8. After reacting for 1 hour at a solid-liquid mass ratio of 1:30, the dechlorination efficiency was measured to be 81.3%. The resulting dechlorinated product was then used in the same type of chlorinated wastewater after elution and other steps, with the operating conditions remaining unchanged.
[0046] After multiple cycles, the dechlorination efficiency of the obtained bismuth-containing complex is shown in the table below.
[0047] Loop count Dechlorination efficiency 1 time 88.6％ 2 times 81.3％ 3 times 86.3％ 4 times 85.5％ 5 times 87.8％ 6 times 87.6％ 7 times 86.5％
[0048] Example 4
[0049] A bismuth-containing composite containing cobalt-doped bismuth oxide and carbon nitride was obtained by calcining a mixture of bismuth nitrate, cobalt nitrate, and melamine at 600°C for 2 hours. The mass fraction of cobalt was 0.4%, the mass fraction of carbon nitride was 1.5%, and the mass fraction of bismuth oxide was 98.1%.
[0050] A bismuth-containing complex was used to treat chlorinated wastewater with a chloride ion concentration of 8046.5 mg / L and a pH of 0.5. The solid-liquid mass ratio of the bismuth-containing complex to the wastewater was 1:20. After one hour of dechlorination reaction, stirring was stopped, and the dechlorination efficiency was measured to be 86.7%. The resulting product was filtered and dried to obtain a dechlorinated product containing bismuth oxychloride, cobalt oxide, and carbon nitride. The mass fractions of bismuth oxychloride were 85.4%, cobalt oxide 1%, and carbon nitride 1.4%, with a residual bismuth oxide mass fraction of 7.1%.
[0051] The dechlorination product was added to an eluent containing an alkali, an oxidant, and water at a solid-liquid mass ratio of 1:20. The alkali was magnesium hydroxide, with a dechlorination product to alkali mass ratio of 1:0.05; the oxidant was sodium peroxide, with a dechlorination product to oxidant mass ratio of 1:0.02. The mixture was irradiated with ultraviolet light at room temperature for 60 minutes. The eluted product was filtered, and the chloride ion concentration in the filtrate was measured, yielding an elution efficiency of 78%. The remaining solid product was dried to obtain a regenerated bismuth-containing composite dechlorinating agent, mainly containing bismuth oxide, cobalt oxide, and carbon nitride, with a bismuth oxide mass fraction exceeding 90%.
[0052] The regenerated bismuth-containing composite dechlorinating agent was used to treat chlorinated wastewater with a chloride ion concentration of 8046.5 mg / L and a pH of 0.5. After reacting for 1 hour at a solid-liquid mass ratio of 1:20, the dechlorination efficiency was measured to be 85.2%. The resulting dechlorinated product was then used in the same type of chlorinated wastewater after elution and other steps, with the operating conditions remaining unchanged.
[0053] After multiple cycles, the dechlorination efficiency of the obtained bismuth-containing complex is shown in the table below.
[0054]
[0055]
[0056] Comparative Example 1
[0057] Pure bismuth oxide was used to treat chlorinated wastewater with a chloride ion concentration of 3283.75 mg / L and a pH of 1. The solid-liquid mass ratio of pure bismuth oxide to wastewater was 1:50. After one hour of dechlorination reaction, stirring was stopped, and the dechlorination efficiency was measured to be 63.9%. The resulting product was filtered and dried to obtain bismuth oxychloride dechlorination product, in which the mass fraction of bismuth oxychloride was 71.17%, and the mass fraction of residual bismuth oxide was 28.83%.
[0058] The dechlorination product was added to an eluent containing an alkali, an oxidant, and water at a solid-liquid mass ratio of 1:40. The alkali was potassium hydroxide, with a product-to-alkali mass ratio of 1:0.05; the oxidant was sodium peroxide, with a product-to-oxidant mass ratio of 1:0.01. The reaction was carried out at room temperature under infrared light for 60 minutes. The eluted product was filtered, and the chloride ion concentration in the filtrate was measured, yielding an elution efficiency of 53%. The remaining solid product was dried to obtain regenerated bismuth oxide dechlorinating agent, mainly containing bismuth oxide with a mass fraction of approximately 62%.
[0059] The regenerated bismuth oxide dechlorinating agent was used to treat chlorinated wastewater with a chloride ion concentration of 3283.75 mg / L and a pH of 1. After reacting for 1 hour at a solid-liquid mass ratio of 1:50, the dechlorination efficiency was measured to be 55.8%. The resulting dechlorinated product was then used in the same type of chlorinated wastewater after elution and other steps, with the operating conditions remaining unchanged.
[0060] After multiple cycles, the dechlorination efficiency of the obtained pure bismuth oxide is shown in the table below.
[0061] Loop count Dechlorination efficiency 1 time 63.9％ 2 times 55.8％ 3 times 47.4％ 4 times 46.9％ 5 times 46.2％ 6 times 38.4％ 7 times 36.2％
[0062] Based on the experimental results of the embodiments and comparative examples, it can be seen that compared with traditional bismuth oxide, the bismuth-containing composite provided by the present invention has significant advantages in dechlorination efficiency as a dechlorination agent and as a regenerated bismuth-containing composite. The reasons are as follows: 1. The introduction of semiconductor elements into the bismuth-containing composite can reduce the stability of the Bi-O covalent bond in the sample, making it easier to break under the attack of hydrogen ions, leading to structural collapse, thereby releasing more bismuth ions and promoting the dechlorination reaction; 2. After the introduction of some semiconductor elements into the bismuth-containing composite, its dechlorination products are prone to forming heterojunctions under light excitation during the elution process, causing electrons to transfer to the introduced semiconductor and form electron-hole pairs. The remaining holes on bismuth oxychloride will cause photocorrosion, promoting the conversion of bismuth oxychloride to bismuth oxide. That is, the introduction of semiconductor elements promotes the elution of chloride ions, thereby increasing the bismuth oxide content in the regenerated bismuth-containing composite, which is conducive to its recycling as a dechlorination agent and can improve the subsequent dechlorination efficiency.
[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. The application of a bismuth-containing complex in chloride ion elution, characterized in that, The application includes the following steps: The bismuth-containing complex was added to the chlorine-containing wastewater for dechlorination. After the dechlorination was completed, the wastewater was filtered and dried to obtain a dechlorination product containing bismuth oxychloride. An elution solution is prepared by mixing alkaline substances, oxidizing agents and water. The dechlorinated product is then added to the elution solution, eluted by light, and then filtered, washed and dried to obtain a regenerated bismuth-containing complex. The solid-liquid mass ratio of the dechlorination product to the elution solution is 1:(10-50), and the mass ratio of the dechlorination product to the alkaline substances and oxidant in the elution solution is 1:(0.05-0.1):(0.01-0.05). Regenerated bismuth-containing complexes are used for the cyclical removal of chlorine from chlorine-containing wastewater; The preparation method of the bismuth-containing complex is as follows: Bismuth nitrate is mixed with ferric nitrate and melamine, or bismuth nitrate with ferric nitrate and titanium dioxide, or bismuth nitrate with copper nitrate and titanium dioxide, or bismuth nitrate with cobalt nitrate and melamine, and calcined at 300-700℃ for 1.5-2.5h to obtain a bismuth-containing composite containing carbon nitride and / or elemental doping. The bismuth oxide content in the bismuth-containing complex is ≥98%.
2. The application according to claim 1, characterized in that, The pH of chlorine-containing wastewater is 0.1-5, and the chloride ion content is 100~30000 mg / L.
3. The application according to claim 1, characterized in that, The solid-liquid mass ratio of the bismuth-containing complex to the chlorine-containing wastewater is 1:(20-100).
4. The application according to claim 1, characterized in that, The alkaline substances are one or more of the following: calcium oxide, calcium hydroxide, sodium hydroxide, potassium hydroxide, lithium hydroxide, carbide slag, iron hydroxide, magnesium hydroxide, zinc hydroxide, ammonia, quaternary ammonium alkali, and guanidine compounds.
5. The application according to claim 1, characterized in that, The oxidizing agent is one or more of the following: hydrogen peroxide, sodium peroxide, calcium peroxide, magnesium peroxide, potassium peroxide, sodium hypochlorite, sodium chlorite, sodium perchlorate, peracetic acid, and potassium permanganate.
6. The application according to claim 1, characterized in that, The dechlorination reaction is carried out under stirring, and the dechlorination time is 0.5-1.5 hours.
7. The application according to claim 1, characterized in that, The light elution time is 10-120 minutes, and the light source is one or more of ultraviolet light, visible light, and infrared light.