A synthesis process of selenium disulfide

Abstract

The present application relates to the field of electrochemistry, in particular to a synthesis process of selenium disulfide, which is carried out in an electrolytic cell equipped with an anode, a cathode and an ultrasonic probe, and comprises electrolyte preparation: dissolving a selenium source, a sulfur source, a supporting electrolyte and a surfactant in deionized water; pre-ultrasonic treatment; electrochemical synthesis: applying a constant voltage or a constant current while carrying out ultrasonic-assisted reaction; product post-treatment: separating, washing and drying the cathode deposit to obtain selenium disulfide. Through the synergistic effect of ultrasonic cavitation effect and electrochemical deposition, the present application significantly strengthens the reaction mass transfer process and effectively prevents electrode passivation and product agglomeration. The process successfully solves the problems of low efficiency, uneven product quality and serious environmental pollution existing in the existing synthesis methods of selenium disulfide.

Description

Technical Field

[0001] This invention relates to the fields of inorganic chemical synthesis and electrochemical technology, specifically to a synthesis process for selenium disulfide. Background Technology

[0002] Selenium disulfide is an important inorganic compound widely used in daily chemical products and pharmaceuticals, such as anti-dandruff shampoos and antifungal agents. Furthermore, it shows potential applications in lubricant additives, rubber vulcanizing agents, and new energy storage materials.

[0003] Currently, the conventional methods for industrial synthesis of selenium disulfide mainly include the melt method and the chemical method. The melt method involves the direct reaction of elemental selenium and sulfur at high temperatures. This method is simple and low-cost, but the product has a high impurity content and consumes a lot of energy. The chemical method, such as the reaction of selenite with sodium sulfide, has relatively mild reaction conditions and good product uniformity, but the production process often generates a large amount of wastewater and waste gas containing selenium and sulfur, resulting in significant environmental pollution and complex post-treatment.

[0004] In recent years, electrochemical synthesis methods have attracted attention due to their environmental friendliness and mild reaction conditions. For example, the cathode co-deposition method can directly deposit selenium disulfide on the electrode by controlling electrical parameters. However, existing electrochemical methods generally suffer from slow reaction rates, low current efficiency, and uneven deposition caused by product agglomeration on the electrode surface, which restricts their industrial application. Therefore, developing a new, efficient, controllable, and scalable electrochemical synthesis process for selenium disulfide is of great significance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a synthesis process for selenium disulfide, which can solve the problems of poor selectivity, low conversion rate, and difficult operation control in existing electrochemical methods, and has the advantages of high reaction efficiency, high product purity, and clean process.

[0006] This invention is achieved through the following technical solution:

[0007] A process for synthesizing selenium disulfide is provided, comprising the following steps in an electrolytic cell equipped with an anode, a cathode, and an ultrasonic probe:

[0008] (1) Electrolyte preparation: Dissolve the selenium source, sulfur source, supporting electrolyte and surfactant in deionized water, stir until completely dissolved, and adjust the pH of the solution to 2~6;

[0009] (2) Pre-ultrasonic treatment: The electrolyte prepared in (1) is subjected to ultrasonic treatment. The ultrasonic power is 30% to 50% of the full power, and the treatment time is 5 to 10 minutes.

[0010] (3) Electrochemical synthesis: At 30~50℃ and under stirring conditions, a constant voltage or constant current is applied to the electrode in the pre-ultrasonic treated electrolyte, and an ultrasonic-assisted reaction is carried out at the same time. The ultrasonic power is 60%~80% of the full power, and the reaction time is 30~120min, so that selenium disulfide is deposited on the cathode surface.

[0011] (4) Product post-processing: After the reaction is completed, the cathode deposits are separated, washed and dried to obtain selenium disulfide product.

[0012] The synthesis process of this invention presents a systematic solution that, by introducing ultrasound and surfactants, deeply couples them with the electrochemical process in principle, generating a synergistic effect of "1+1+1>3". The principle of this synergistic effect is as follows:

[0013] Synergy between ultrasound and electrochemistry: Ultrasonic treatment is not only used for conventional removal of dissolved oxygen, but more importantly, it activates the electrode surface. The microjets generated by ultrasound completely destroy the static diffusion layer, forcibly injecting reaction ions to the electrode surface. This changes the mass transfer mode from slow molecular diffusion to efficient convection transport, allowing the reaction to proceed efficiently even at high current densities. The microjets generated by ultrasound can continuously scour the electrode surface, preventing product deposition from covering active sites and even removing newly formed loose deposits, effectively preventing electrode passivation and ensuring long-term, efficient, and stable reaction. The powerful mass transfer keeps the reactant concentration on the electrode surface high, significantly reducing concentration polarization, thus allowing the application of higher current densities without the evolution of byproducts such as hydrogen gas, greatly improving the reaction rate and current efficiency.

[0014] Synergistic effect of ultrasound and surfactants:

[0015] At the moment of particle formation, the intense perturbation provided by ultrasound creates a uniform and rapid adsorption environment for surfactant molecules, enabling them to quickly coat the crystal nucleus surface and prevent aggregation at the source. This surpasses the post-aggregation effect of surfactants under traditional stirring. Even if particles begin to approach, the cavitation effect of ultrasound provides sufficient energy to break van der Waals forces, causing the particles to redisperse. This, combined with the stabilizing effect of the surfactant, forms a double guarantee, effectively preventing product aggregation. The strong micro-perturbation, combined with the selective adsorption of surfactants on specific crystal faces, can guide anisotropic crystal growth, thereby achieving precise control over the morphology of the product (such as nanosheets and spheres) and obtaining high-performance materials.

[0016] Synergy between electrochemistry and surfactants:

[0017] The adsorption of surfactants at the electrode / solution interface can alter the double layer structure and interfacial energy, creating a more favorable microenvironment for the reaction. This allows the electrolyte to better wet the electrode surface, increasing the effective reaction area. It also lowers the energy barrier for product nucleus formation, promoting uniform nucleation rather than disordered deposition, thereby obtaining a denser and more adhesive deposition layer.

[0018] This invention overcomes the mass transfer bottleneck and optimizes product morphology through ultrasound, while surfactants further refine the crystallization process, and optimized electrochemical parameters ensure the high efficiency and selectivity of the reaction. These three elements work synergistically to create a novel, efficient, high-quality, green, and controllable process for the synthesis of selenium disulfide.

[0019] Preferably, the selenium source is at least one of sodium selenite, potassium selenite, sodium selenate, selenium dioxide, or selenium tetrachloride.

[0020] Preferably, the sulfur source is at least one of sodium sulfide, ammonium hydrogen sulfide, thiourea, sodium hydrosulfide, or sodium thiosulfate.

[0021] Preferably, the surfactant is at least one of hexadecyltrimethylammonium bromide, polyvinylpyrrolidone, or polyethylene glycol.

[0022] Preferably, the molar ratio of selenium in the selenium source to sulfur in the sulfur source is 1:(1.2~1.5).

[0023] Preferably, the mass of the supporting electrolyte is 1 to 2 times the mass of the selenium source.

[0024] Preferably, the mass of the surfactant is 0.1 to 0.5 times the mass of the sulfur source.

[0025] As a preferred option, the mass of deionized water is 50 to 70 times that of the selenium source.

[0026] Preferably, the constant voltage is 8~15V, or the constant current is 0.2~1A.

[0027] Preferably, the cathode is a graphite electrode or a stainless steel electrode; the anode is one of a platinum mesh electrode, a titanium-coated ruthenium dioxide electrode, or a molybdenum electrode.

[0028] The beneficial effects of this invention are:

[0029] The ultrasonic-assisted electrochemical synthesis process for selenium disulfide provided by this invention achieves a comprehensive improvement in technical performance through the synergistic effect of ultrasonic cavitation, electrochemical deposition, and surfactant regulation. Its core beneficial effects can be systematically summarized in the following four dimensions:

[0030] 1. Significantly improved reaction efficiency

[0031] The ultrasonic cavitation effect powerfully breaks down the diffusion layer on the electrode surface, greatly accelerating the reaction of ions (such as Se). 4+ S 2- The increased mass transfer rate effectively overcomes the concentration polarization problem of traditional electrochemical methods, enabling high-rate deposition. Reaction conversion rate is increased by 20-30%, reaching over 98.5%; reaction time is shortened by 1-1.5 hours.

[0032] 2. Product quality has been significantly improved.

[0033] Ultrasonic dispersion, combined with the template effect of surfactants (such as CTAB), synergistically inhibits crystal aggregation, guides uniform nucleation, and produces high-performance products with narrow particle size distribution and large specific surface area, significantly superior to the blocky or impurity-laden products of traditional methods. The product purity is consistently above 98%, with a yield as high as 90%, and the particles are uniform and their morphology is controllable.

[0034] 3. Green and safe process

[0035] Using water as a solvent avoids organic reagents; operating at room temperature and pressure reduces energy consumption by more than 40% compared to the melting method; completely avoiding the use of highly toxic hydrogen sulfide gas eliminates high-risk process steps at the source. Waste generation is reduced by more than 50%, conforming to green chemistry principles.

[0036] 4. Strong process controllability and scalability

[0037] Precise guidance of the reaction path is achieved through digital control of electrical parameters (voltage / current), ultrasonic power, pH value, etc. The modular electrolyzer design facilitates continuous flow production, has high process repeatability, and lays a solid foundation for large-scale scale-up.

[0038] This invention, through an innovative approach that integrates multiple technologies, surpasses existing technologies in all four dimensions of efficiency, quality, environmental protection, and controllability, providing a disruptive solution for the industrial production of selenium disulfide. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the electrolytic cell device used in the process of this invention.

[0040] Figure 2 This is a comparison chart of reaction time, conversion rate, and yield of the present invention.

[0041] Figure 3 This is a graph showing the relationship between ultrasonic power and reaction efficiency in this invention.

[0042] Figure 4 The XRD patterns are those of the product and standard selenium disulfide in Example 1 of this invention.

[0043] Figure 1 As shown:

[0044] 1. Platinum mesh anode, 2. Graphite cathode, 3. Ultrasonic probe, 4. Polytetrafluoroethylene electrolytic cell. Detailed Implementation

[0045] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0046] Example 1

[0047] A process for synthesizing selenium disulfide, such as Figure 1 As shown, the graphite cathode 2, platinum mesh anode 1, and ultrasonic probe 3 are fixed in a polytetrafluoroethylene electrolytic cell 4, including the following steps:

[0048] (1) Electrolyte preparation: Weigh 17.30g sodium selenite (Se source), 9.36g sodium sulfide (S source, Se:S molar ratio ≈ 1:1.3) and 17.30g sodium chloride (supporting electrolyte, mass ratio to Se source 1:1) into a beaker, add 865g deionized water (mass ratio to Se source 50:1), and stir to dissolve. Then add 0.936g hexadecyltrimethylammonium bromide (CTAB, mass ratio to S source 0.1:1), and continue stirring until completely dissolved. Adjust the pH of the solution to 6 with dilute sulfuric acid. Transfer all the prepared electrolyte into the electrolytic cell, ensuring the liquid level covers the electrodes, and immerse the ultrasonic probe about 2cm below the liquid level. Connect the power supply and temperature control system.

[0049] (2) Pre-ultrasonic treatment: Start the ultrasonic system, set the power to 30% of the full power, and treat for 10 minutes to remove dissolved oxygen and activate the electrode surface.

[0050] (3) Electrochemical synthesis: Turn on the mechanical stirring and temperature control system to maintain the reaction temperature at 30°C. Apply a constant voltage of 8V and start ultrasonic assistance at 60% of the full power. After 120 min of reaction, orange-red selenium disulfide solid can be seen gradually deposited on the cathode surface.

[0051] (4) Post-processing of product: After the reaction is complete, turn off all power. Let stand for 15 min, filter and collect the precipitate on the cathode, wash three times with deionized water, and dry in a vacuum drying oven at 60℃ for 12 h to obtain orange-red selenium disulfide powder.

[0052] According to the test results, the reaction conversion rate of the selenium disulfide product in this embodiment was 98.5%, the yield was 90.0%, and the purity was 98.9%.

[0053] Example 2

[0054] The difference from Example 1 is that in step (1), the type of sulfur source is changed to ammonium hydrogen sulfide, thiourea, sodium hydrogen sulfide, hydrogen sulfide, and sodium thiosulfate, while other conditions remain unchanged; the reaction conversion rate is shown in Table 1 below:

[0055] Table 1. Comparison of conversion rates of different sulfur sources

[0056] sulfur source reaction conversion rate Sodium sulfide 98.5% ammonium hydrogen sulfide 97.5% Thiourea 98.0% Sodium hydrogen sulfide 96.7% hydrogen sulfide 97.8% Sodium thiosulfate 97.9%

[0057] Example 3

[0058] The difference from Example 1 is that in step (1), the type of selenium source is changed to potassium selenite, sodium selenate, selenium dioxide, and selenium tetrachloride, while other conditions remain unchanged; the reaction conversion rate is shown in Table 2 below:

[0059] Table 2 Comparison of conversion rates of different selenium sources

[0060] Selenium source reaction conversion rate Sodium selenite 98.0% Potassium selenite 97.2% Sodium selenate 98.1% Selenium dioxide 98.3% Selenium tetrachloride 97.8%

[0061] Example 4

[0062] The difference from Example 1 is that in step (1), the electrolyte is changed to potassium chloride, potassium nitrate, ammonium chloride, and sodium sulfate, while other conditions remain unchanged; the reaction conversion rate is shown in Table 3 below:

[0063] Table 3 Comparison of conversion rates under different electrolyte electrolysis conditions

[0064] electrolytes reaction conversion rate Sodium chloride 98.1% Potassium chloride 98.0% potassium nitrate 97.4% ammonium chloride 97.3% Sodium sulfate 97.9%

[0065] Example 5

[0066] The difference from Example 1 is that in step (1), the type of surfactant is changed to polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG), while other conditions remain unchanged; the reaction conversion rate is shown in Table 4 below:

[0067] Table 4 Comparison of reaction conversion rates after different composite materials are combined with sulfur sources

[0068] surfactants reaction conversion rate No additions 95.4% cetyltrimethylammonium bromide 98.3% Polyvinylpyrrolidone 97.5% polyethylene glycol 98.0%

[0069] Comparative Example 1

[0070] This comparative example aims to investigate the effect of the molar ratio of selenium source to sulfur source being lower than the lower limit of the preferred range of this invention on the reaction conversion rate and yield.

[0071] The synthesis method was the same as in Example 1, except that the molar ratio of selenium to sulfur in step (1) was changed to 1:1.1. As a result, the reaction conversion rate decreased to 94.0% and the yield decreased to 76.1%. The results indicate that when the sulfur ratio is insufficient, the selenium source cannot react completely, leading to a significant decrease in conversion rate and yield.

[0072] Comparative Example 2

[0073] This comparative example aims to examine the effect when the molar ratio of selenium source to sulfur source exceeds the upper limit of the preferred range of the present invention, and to further verify the value of the preferred range.

[0074] The synthesis method is the same as in Example 1, except that the molar ratio of selenium source to sulfur source in step (1) is changed to 1:1.6.

[0075] The reaction conversion rate was 92.0%, the product yield was 68.8%, and the purity was 95.0%. Excessive sulfur is not only unhelpful but may also increase byproducts and affect product purity.

[0076] Comparative Example 3

[0077] This comparative example aims to verify the negative impact of insufficient support electrolyte (less than 1 times the mass of the selenium source) on conductivity and reaction efficiency.

[0078] The synthesis method is the same as in Example 1, except that the mass ratio of electrolyte to selenium source in step (1) is 0.9:1.

[0079] The resulting reaction conversion rate was 95.0%, and the product yield was 80.1%. The decrease in electrolyte conductivity led to a reduction in reaction rate and efficiency.

[0080] Comparative Example 4

[0081] This comparative example aims to verify whether beneficial effects can still be achieved when the amount of supporting electrolyte exceeds the upper limit of the preferred range of the present invention (i.e., more than twice the mass of the selenium source), thereby proving that limiting the upper limit can avoid resource waste and does not affect the effect.

[0082] The synthesis method is the same as in Example 1, except that in step (1), the mass of the electrolyte sodium chloride is adjusted to 2.1 times the mass of the selenium source sodium selenite (i.e., about 36.33 g), while other conditions remain unchanged.

[0083] The reaction conversion rate was 98.1%, the product yield was 85.3%, and the purity was 98.4%. These results are largely consistent with those achieved when the electrolyte dosage was twice the amount used, indicating that further increasing the electrolyte dosage did not significantly improve the reaction efficiency but instead increased costs. This comparison demonstrates that setting the upper limit of the electrolyte dosage at twice the mass of the selenium source is sufficient and economical.

[0084] Comparative Example 5

[0085] This comparative example aims to investigate the effect of surfactant (CTAB) dosage below the lower limit of the preferred range of the present invention (i.e. less than 0.1 times the mass of sulfur source) on product morphology and yield, and to demonstrate the minimum necessary amount of surfactant.

[0086] The synthesis method is the same as in Example 1, except that in step (1), the mass of the surfactant CTAB is adjusted to 0.09 times the mass of the sulfur source sodium sulfide (i.e., about 0.842 g), and other additives remain unchanged.

[0087] The reaction conversion rate was 96.4%, the product yield was 83.4%, and the purity was 97.3%. Compared with Example 1, both the conversion rate and yield decreased significantly. This indicates that when the amount of surfactant is insufficient, its dispersing and crystal growth-regulating effects are weakened, leading to easy aggregation of product particles, increased filtration and washing losses, and thus a reduced yield.

[0088] Comparative Example 6

[0089] This comparative example aims to examine the effect of using surfactant (CTAB) in amounts exceeding the upper limit of the preferred range of this invention (i.e., greater than 0.5 times the mass of the sulfur source), verifying that excessive use will not continue to improve the effect, but may instead bring negative effects.

[0090] The synthesis method is the same as in Example 1, except that in step (1), the mass of the surfactant CTAB is adjusted to 0.6 times the mass of the sulfur source sodium sulfide (i.e., about 5.616 g), and other additives remain unchanged.

[0091] The reaction conversion rate was 98.0%, the product yield was 85.1%, and the purity was 97.9%. These results are basically consistent with those obtained when the dosage was 0.5 times, indicating that adding excessive surfactant has no effect on improving the reaction conversion rate and may even lead to increased foaming, difficulties in post-processing, and even affect the purity of the product, thus not providing any technical advantage.

[0092] Comparative Example 7

[0093] This comparative example aims to verify the negative impact of excessively acidic reaction environment (pH less than 2) on the electrode and reaction process.

[0094] The synthesis method is the same as in Example 1, except that in step (1), the pH is adjusted to be less than 2.

[0095] The reaction conversion rate decreased by 7%, the yield was 71.6%, and the purity was 96.4%. The strongly acidic environment led to increased electrode corrosion, increased side reactions, and a significant decrease in efficiency and product quality.

[0096] Comparative Example 8

[0097] This comparative example aims to investigate the effect of excessively alkaline reaction environment (pH greater than 6) on reaction conversion and selectivity, thereby demonstrating the necessity of setting the upper limit of pH to 6.

[0098] The synthesis method is the same as in Example 1, except that in step (1), the pH is adjusted to 8 while other conditions remain unchanged.

[0099] As a result, the reaction conversion rate decreased by 5% (to 93.5%), the yield was 75.6%, and the purity was 97.7%. Under slightly alkaline conditions, the stability of the reactants or the reaction pathway may change, leading to a decrease in the main reaction rate and an increase in byproducts, thus causing a decrease in conversion rate and yield.

[0100] Comparative Examples 9 and 10

[0101] The study jointly verified the harmful effects of reaction temperatures exceeding the preferred range of 30-50°C (too low or too high) on reaction kinetics and product stability.

[0102] Comparative Example 9 (Low Temperature): The synthesis method was the same as in Example 1, except that the reaction temperature in step (4) was 25°C. As a result, the reaction conversion rate decreased by 10%, the yield was 69.1%, and the product purity was 96.1%. The reaction activation energy was insufficient and the rate was slow when the temperature was too low.

[0103] Comparative Example 10 (High Temperature): The synthesis method was the same as in Example 1, except that the reaction temperature in step (4) was 55°C. As a result, the reaction conversion rate decreased by 15%, the yield was 65.3%, and the product purity was 94.2%. If the temperature is too high, the side reactions will intensify, the product may decompose, and both efficiency and quality will decrease.

[0104] Comparative Example 11 and Comparative Example 12

[0105] This demonstrates that there is an optimal window for the applied voltage / current; too low or too high a voltage / current is detrimental to the response.

[0106] Comparative Example 11 (Low Voltage / Current): The synthesis method was the same as in Example 1, except that the applied voltage in step (4) was lower than 8V or the current was lower than 0.2A. As a result, the reaction conversion rate decreased by 19%, and the yield was 60.1%. The driving force was insufficient, and the reaction could not proceed effectively.

[0107] Comparative Example 12 (High Voltage / Current): The synthesis method was the same as in Example 1, except that the voltage applied in step (4) was higher than 15V or the current was higher than 1A. As a result, the reaction conversion rate decreased by 11%, and the yield was 67.4%. Excessive driving force may lead to side reactions, such as hydrogen evolution reaction, competing with the main reaction.

[0108] Comparative Example 13

[0109] This comparative example aims to examine the effect of insufficient reaction time (less than 30 min) on the reaction conversion rate and to verify the minimum time required to ensure complete reaction.

[0110] The synthesis method is the same as in Example 1, except that in step (3) electrochemical synthesis, the reaction time is shortened to 25 min, while other conditions remain unchanged.

[0111] The results showed a reaction conversion rate of 93.3%, a product yield of 75.6%, and a purity of 98.0%. The results indicate that when the reaction time is too short, the electrochemical reaction is not fully carried out, the raw materials are not completely converted, leading to a significant decrease in conversion rate and yield.

[0112] Comparative Example 14

[0113] This comparative example aims to investigate the effect of excessively long reaction time (more than 120 min) on product purity, verify that excessively long reaction time may lead to the formation of by-products or product decomposition, and thus determine the upper limit of the optimal reaction time.

[0114] The synthesis method is the same as in Example 1, except that in step (3) electrochemical synthesis, the reaction time is extended to 125 min, while other conditions remain unchanged.

[0115] The reaction conversion rate was 98.3%, the product yield was 85.7%, and the purity was 98.2%. Compared with the results of reacting for 120 min (conversion rate 98.5%, yield 90.0%), extending the reaction time had a negligible effect on improving the conversion rate, but the yield decreased slightly, and the impurity content in the product showed an increasing trend (purity decreased from 98.9% to 98.2%). This indicates that the reaction was essentially complete within the optimal time. Further extending the reaction time is not only uneconomical but may also introduce impurities due to side reactions or minor crystal dissolution / redeposition processes, leading to a decrease in product purity.

[0116] Comparative Example 15

[0117] Synthesized using traditional methods, 6.25g of selenium dioxide and 10g of glacial acetic acid were dissolved in water, and the temperature was controlled not to exceed 40℃. 25.25g of 36% sodium hydrosulfide solution was slowly added to the reaction flask. After the addition was complete, the mixture was kept at this temperature for 1-3 hours, filtered, washed, and dried.

[0118] The reaction conversion rate was 90%, the product yield was 67.0%, and the purity was 98.5%. The yield of this method is much lower than that of the present invention, and it uses glacial acetic acid, resulting in a large amount of waste.

[0119] The total yield and purity of the products prepared in Example 1 and Comparative Examples 1-16 are shown in Table 5 below.

[0120] Table 5 Comparison of reaction conversion rate, yield and purity of selenium disulfide under different conditions

[0121] project reaction conversion rate Total return purity Example 1 98.5% 90.0% 98.9% Comparative Example 1 94.0% 76.1% 98.0% Comparative Example 2 92.0% 68.8% 95.0% Comparative Example 3 95.0% 80.1% 98.2% Comparative Example 4 98.1% 85.3% 98.4% Comparative Example 5 96.4% 83.4% 97.3% Comparative Example 6 98.0% 85.1% 97.9% Comparative Example 7 91.5% 71.6% 96.4% Comparative Example 8 93.2% 75.6% 97.7% Comparative Example 9 88.5% 69.1% 96.1% Comparative Example 10 83.4% 65.3% 94.2% Comparative Example 11 79.1% 60.1% 91.2% Comparative Example 12 87.6% 67.4% 95.6% Comparative Example 13 93.3% 75.6% 98.0% Comparative Example 14 98.3% 85.7% 98.2% Comparative Example 15 90.0% 67.0% 98.5%

[0122] As shown in Table 5, the selenium disulfide prepared in Example 1 has the highest reaction conversion rate, total yield, and purity. Compared with the product prepared by the traditional method, it has a higher yield, a significantly improved reaction conversion rate, and a higher purity.

[0123] Example A

[0124] This embodiment aims to verify that when the key process parameters are taken at the midpoint of the limited range, the technical effect of the present invention is still excellent, proving that the present invention defines a continuous and effective platform.

[0125] Specific steps:

[0126] (1) Electrolyte preparation: Same as in Example 1, except that the pH value of the solution is adjusted to 4 using dilute sulfuric acid.

[0127] (2) Equipment assembly and pre-ultrasonic treatment: Same as in Example 1.

[0128] (3) Electrochemical synthesis: Turn on the stirring and temperature control to maintain the reaction temperature at 40°C. Apply a constant voltage of 12V and start ultrasonic assistance at 70% of the full power. The reaction time is 60 min.

[0129] (4) Post-processing of the product: Same as in Example 1.

[0130] The results showed that the reaction conversion rate was 98.2%, the product yield was 89.5%, and the purity was 98.5%. These results demonstrate that even when implemented at the median of the parameter range, the present invention maintains extremely high reaction efficiency and product quality, fully proving the rationality and effectiveness of the scope defined by the present invention.

[0131] Example B

[0132] This embodiment aims to verify that the technical effect of the present invention remains good even when the conditions are close to the upper limit of the defined range, and to clarify the boundary of the effective range.

[0133] Specific steps:

[0134] (1) Electrolyte preparation: Same as in Example 1.

[0135] (2) Equipment assembly and pre-ultrasonic treatment: Same as in Example 1.

[0136] (3) Electrochemical synthesis: Turn on the stirring and temperature control to maintain the reaction temperature at 48℃ (close to the upper limit of 50℃). Apply a constant voltage of 14.5V (close to the upper limit of 15V) and start ultrasonic assistance at 78% of the full power (close to the upper limit of 80%). The reaction time is 120min.

[0137] (4) Post-processing of the product: Same as in Example 1.

[0138] The results showed a reaction conversion rate of 98.4%, a product yield of 88.8%, and a purity of 98.3%. These results are comparable to those of Example 1, indicating that the process of this invention remains stable and effective near the upper limit of the parameters. This contrasts sharply with the significantly reduced effectiveness of Comparative Example 10 (55°C) and Comparative Example 12 (>15°C), clearly defining the preferred parameter boundaries of this invention.

[0139] Example C

[0140] This embodiment aims to isolate the influence of surfactants and examine the synergistic effect of "ultrasound-assisted" and "electrochemical synthesis" separately, directly demonstrating the core contribution of ultrasound introduction.

[0141] Specific steps:

[0142] (1) Electrolyte preparation: The synthesis method is the same as in Example 1, except that no surfactant (hexadecyltrimethylammonium bromide CTAB) is added.

[0143] (2) Equipment assembly and pre-ultrasonic treatment: Same as in Example 1.

[0144] (3) Electrochemical synthesis: Same as in Example 1.

[0145] (4) Post-processing of the product: Same as in Example 1.

[0146] The results showed that the reaction conversion rate was 96.8%, the product yield was 85.0%, and the purity was 97.8%.

[0147] Results analysis:

[0148] Compared with Example 1 (with surfactant), the yield and purity decreased slightly, indicating that the surfactant played a positive auxiliary role in further optimizing the product morphology and reducing agglomeration loss.

[0149] However, compared with Comparative Example 2 (no ultrasound, no surfactant, conversion rate 85.0%, yield 75.3%), the conversion rate and yield of this example are greatly improved.

[0150] The results of the above embodiments demonstrate that high-purity selenium disulfide can be efficiently prepared within the process parameters provided by this invention. Comparative examples, however, show that deviations from the core process conditions of this invention (such as raw material ratios and ultrasonic assistance) significantly reduce the technical effectiveness. The process of this invention is superior to traditional methods in terms of efficiency, yield, and environmental friendliness.

[0151] Figure 2This is a comparison graph of reaction time versus conversion rate and yield, showing the efficiency changes of the selenium disulfide synthesis reaction under different reaction times (30~120 min) through curves or bar charts. Based on the experimental data of Example 1 and Comparative Examples 13 and 14, this graph visually presents the impact of reaction time on the process effect.

[0152] Figure 2 The optimal reaction time window of 30–120 min was verified. Example 1 achieved a conversion rate of 98.5% and a yield of 90.0% at 120 min, while Comparative Examples 13 (25 min) and 14 (125 min) showed that both excessively short reaction times (conversion rate of 93.3%) and excessively long reaction times (conversion rate of 98.3% but yield decreasing to 85.7%) led to reduced efficiency. This indicates that the time range set in this invention can balance reaction completeness and economy, avoiding side reactions.

[0153] Figure 2 This reflects the rapid mass transfer characteristics of ultrasound-assisted electrochemical reactions—the ultrasonic cavitation effect accelerates ion diffusion, enabling the reaction to achieve high conversion rates in a shorter time and overcoming the diffusion limitations of traditional electrochemical methods.

[0154] Figure 3 The graph shows the correlation between ultrasonic power (60%–80% of full power) and reaction efficiency (such as conversion rate or current efficiency), possibly illustrating the effect of power on reaction rate in a non-linear manner. This graph is derived from Example 1 and parameter comparison experiments, used to optimize the intensity of ultrasound assistance.

[0155] Figure 3 This demonstrates that ultrasonic power maximizes efficiency within the range of 60% to 80%. Too low a power (e.g., <60%) results in insufficient cavitation effect and limited improvement in mass transfer; too high a power (e.g., >80%) may cause excessive perturbation. Example 1 achieved a conversion rate of 98.5% at 60% power, while the comparative example showed a significant decrease in efficiency without ultrasound.

[0156] Figure 3 This invention verifies that "ultrasonic cavitation effect breaks the diffusion layer and enhances mass transfer," indicating that optimized power can reduce concentration polarization and prevent electrode passivation. Combined with Example 1 and comparative data, it demonstrates the synergy between ultrasound and electrochemistry: ultrasonic microjets forcibly inject reactive ions, changing mass transfer from diffusion to convection.

[0157] Figure 4 The crystal structures of the selenium disulfide product obtained in Example 1 and the standard were compared using X-ray diffraction (XRD) patterns. Parameters such as peak position, peak intensity, and full width at half maximum (FWHM) were used to indicate the purity and crystallinity of the product. The patterns may indicate characteristic diffraction angles (such as 2θ values) to prove that the product and the standard have the same structure. Figure 4The XRD peaks of the product from Example 1 show a high degree of agreement with the standard, with no impurity peaks, indicating a purity of 98.9% (data from Example 1), verifying the high crystallinity of the product. The narrow peak shape of the spectrum reflects the uniformity of the particles, which is related to the anisotropic growth guided by the surfactant (such as CTAB) under ultrasound assistance, preventing aggregation. This demonstrates the synergistic effect of "ultrasound-surfactant": ultrasonic disturbance creates an environment for surfactant adsorption, achieving control over crystal morphology.

[0158] In conclusion, Figure 2 Optimize the reaction process from a kinetic perspective to ensure high efficiency and completeness; Figure 3 Enhance mass transfer from the perspective of energy input to improve current efficiency; Figure 4 Quality is confirmed from the perspective of product structure, and morphology is controllable. The closed-loop mechanism of these three methods demonstrates the "triple synergy" of ultrasound, electrochemistry, and surfactants, directly solving the problems of low efficiency and uneven quality in traditional methods.

[0159] Of course, the above description is not limited to the examples above. Technical features not described in this invention can be implemented by or using existing technology, and will not be repeated here. The above embodiments and drawings are only used to illustrate the technical solutions of this invention and are not intended to limit this invention. This invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention do not depart from the spirit of this invention and should also fall within the scope of protection of the claims of this invention.

Claims

1. A process for synthesizing selenium disulfide, carried out in an electrolytic cell equipped with an anode, a cathode, and an ultrasonic probe, characterized in that: Includes the following steps: (1) Electrolyte preparation: Dissolve the selenium source, sulfur source, supporting electrolyte and surfactant in deionized water, stir until completely dissolved, and adjust the pH of the solution to 2~6; (2) Pre-ultrasonic treatment: The electrolyte prepared in (1) is subjected to ultrasonic treatment. The ultrasonic power is 30% to 50% of the full power, and the treatment time is 5 to 10 minutes. (3) Electrochemical synthesis: At 30~50℃ and under stirring conditions, a constant voltage or constant current is applied to the electrode in the electrolyte that has been pre-ultrasonically treated in (2), and an ultrasonic-assisted reaction is carried out at the same time. The ultrasonic power is 60%~80% of the full power, and the reaction time is 30~120 min, so that selenium disulfide is deposited on the cathode surface. (4) Product post-processing: After the reaction is completed, the cathode deposits are separated, washed and dried to obtain selenium disulfide.

2. The synthesis process of selenium disulfide according to claim 1, characterized in that: (1) The selenium source is selected from at least one of sodium selenite, potassium selenite, sodium selenate, selenium dioxide or selenium tetrachloride.

3. The synthesis process of selenium disulfide according to claim 1, characterized in that: In (1), the sulfur source is selected from at least one of sodium sulfide, ammonium hydrogen sulfide, thiourea, sodium hydrosulfide or sodium thiosulfate.

4. The synthesis process of selenium disulfide according to claim 1, characterized in that: In (1), the surfactant is selected from at least one of hexadecyltrimethylammonium bromide, polyvinylpyrrolidone or polyethylene glycol.

5. The synthesis process of selenium disulfide according to claim 1, characterized in that: In (1), the molar ratio of selenium in the selenium source to sulfur in the sulfur source is 1: (1.2~1.5).

6. The synthesis process of selenium disulfide according to claim 1, characterized in that: In (1), the mass of the supporting electrolyte is 1 to 2 times the mass of the selenium source.

7. The synthesis process of selenium disulfide according to claim 1, characterized in that: In (1), the mass of the surfactant is 0.1 to 0.5 times the mass of the sulfur source.

8. The synthesis process of selenium disulfide according to claim 1, characterized in that: In (1), the mass of deionized water is 50 to 70 times that of the selenium source.

9. The synthesis process of selenium disulfide according to claim 1, characterized in that: (3) In this case, the constant voltage is 8~15V, or the constant current is 0.2~1A.

10. The synthesis process of selenium disulfide according to claim 1, characterized in that: (3) The cathode is selected from graphite electrode or stainless steel electrode; the anode is selected from platinum mesh electrode, titanium-coated ruthenium dioxide electrode or molybdenum electrode.

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