Apparatus and method for recycling sulfuric acid

Abstract

To provide a novel method for treating waste sulfuric acid and improving the quality of recycled sulfuric acid.SOLUTION: An apparatus for recycling sulfuric acid is provided. A container has an internal space. An inlet is located on a first side of the container and introduces a liquid containing sulfuric acid and hydrogen peroxide. An outlet is located on a second side of the container and discharges the treated liquid from the container. The first and second sides face each other. An infrared lamp and an ultraviolet lamp are located in the inner space of the container and contact the liquid. Infrared light emitted from the infrared lamp and ultraviolet light emitted from the ultraviolet lamp decompose hydrogen peroxide in the liquid into water and oxygen. Infrared light heats the liquid and oxygen is discharged from an air hole.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an apparatus and method for recycling sulfuric acid. [Background technology]

[0002] In semiconductor manufacturing processes, electronic-grade sulfuric acid is used to prepare Caro's acid solution for wafer cleaning. Waste sulfuric acid generated during this cleaning process is the largest wastewater produced. In 2021, the amount of waste sulfuric acid generated reached 365,000 tons. As the semiconductor industry expands, the amount of waste sulfuric acid (which is difficult to remove) is expected to reach 516,000 tons. Waste sulfuric acid, consisting of more than 50 wt% sulfuric acid and 1 to 5 wt% hydrogen peroxide, cannot be directly reused due to its strong oxidizing properties. The current treatment method for the major contaminants in waste sulfuric acid, such as hydrogen peroxide, involves adding hydrochloric acid as a catalyst to decompose the hydrogen peroxide to below 50 mg / L. However, this process produces harmful substances such as chlorine gas and leaves chloride ions in the purified sulfuric acid. Therefore, this is not an optimal purification method. Furthermore, while commercially available enzymes can be added to remove hydrogen peroxide from waste sulfuric acid, this is expensive and not very effective. Furthermore, enzymes have the problem of chemical residues and changes in the quality of the acid, making it difficult to use the acid without removing the enzymes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2019 / 0174802A1 [Patent Document 2] Taiwan Patent Application Publication No. TW559940B Summary of the Invention [Problem to be solved by the invention]

[0004] New methods are needed to treat waste sulfuric acid and improve the quality of the recycled sulfuric acid. [Means for solving the problem]

[0005] One embodiment of the present disclosure provides an apparatus for recycling sulfuric acid, including a container, an inlet, an outlet, an infrared (IR) lamp, an ultraviolet (UV) lamp, a bracket, and a lid. The container has an interior space. The inlet is located on a first side of the container. The inlet is used to introduce a liquid containing sulfuric acid and hydrogen peroxide. The liquid can be introduced into the container from the inlet via a pump. The outlet is located on a second side of the container. The outlet is used to discharge the treated liquid from the container. The first and second sides are opposite each other. The infrared lamp is located in the interior space of the container. The infrared lamp is adapted to contact the liquid. The ultraviolet lamp is located in the interior space of the container. The ultraviolet lamp is adapted to contact the liquid. The bracket is located in the interior space of the container. The bracket connects the infrared lamp and the ultraviolet lamp. The lid covers the upper side of the container. The lid has an air hole. The air hole can be connected to an exhaust device. The infrared light emitted from the infrared lamp and the ultraviolet light emitted from the ultraviolet lamp decompose the hydrogen peroxide in the liquid into water and oxygen. The infrared heats the liquid and oxygen is expelled through the air vent. The liquid is preferably heated to between 90°C and 130°C.

[0006] In some embodiments, the device further comprises a three-way valve connected to the outlet and used to exhaust oxygen.

[0007] In some embodiments, the infrared radiation has a wavelength of 1500 nm to 6500 nm.

[0008] In some embodiments, the wavelength of the ultraviolet light is between 230 nm and 275 nm.

[0009] In some embodiments, the energy density of each of the infrared and ultraviolet light is 0.1 W / cm 2 to 16W / cm 2is.

[0010] In some embodiments, the ratio of infrared to ultraviolet energy densities is between 4:1 and 20:1.

[0011] In some embodiments, the device further includes other infrared lamps and other ultraviolet lamps, wherein the ratio of the total cross-sectional area of ​​the infrared lamps to the cross-sectional area of ​​the container is 1:100 to 5:100, and the ratio of the total cross-sectional area of ​​the ultraviolet lamps to the cross-sectional area of ​​the container is 1:100 to 5:100.

[0012] In some embodiments, the infrared lamps are arranged in a cross-section of the container to form a first circle, and the ultraviolet lamps are arranged in a cross-section of the container to form a second circle, the first and second circles being concentric, and the diameter of the first circle being greater than the diameter of the second circle.

[0013] In some embodiments, the flow rate of the liquid introduced through the inlet is between 0.5 m / hr and 3 m / hr.

[0014] In some embodiments, the sulfuric acid concentration of the liquid is between 50 wt% and 70 wt%.

[0015] In some embodiments, the hydrogen peroxide concentration of the liquid is between 10,000 mg / L and 60,000 mg / L, and the hydrogen peroxide concentration of the treated liquid is 50 mg / L or less.

[0016] In some embodiments, the sidewall of the container has a textured structure.

[0017] One embodiment of the present disclosure provides a method for recycling sulfuric acid, the method including the steps of: providing a liquid containing sulfuric acid and hydrogen peroxide in a container; decomposing the hydrogen peroxide in the liquid into water and oxygen using infrared and ultraviolet light, where the infrared light heats the liquid to 90°C to 130°C; and collecting the treated liquid.

[0018] In some embodiments, the method further comprises removing oxygen upon decomposition of hydrogen peroxide into water and oxygen.

[0019] In some embodiments, the infrared radiation has a wavelength of 1500 nm to 6500 nm.

[0020] In some embodiments, the wavelength of the ultraviolet light is between 230 nm and 275 nm.

[0021] In some embodiments, the energy density of each of the infrared and ultraviolet light is 0.1 W / cm 2 to 16W / cm 2 is.

[0022] In some embodiments, the ratio of infrared to ultraviolet energy densities is between 4:1 and 20:1.

[0023] In some embodiments, the sulfuric acid concentration of the liquid is between 50 wt% and 70 wt%.

[0024] In some embodiments, the hydrogen peroxide concentration of the liquid is between 10,000 mg / L and 60,000 mg / L, and the hydrogen peroxide concentration of the treated liquid is 50 mg / L or less. [Effects of the Invention]

[0025] The present disclosure effectively increases the reaction rate (e.g., increases the decomposition efficiency of hydrogen peroxide in the same treatment time) by combining ultraviolet and infrared light.

[0026] Detailed description will be given in the following embodiments with reference to the accompanying drawings. [Brief explanation of the drawings]

[0027] The present disclosure can be more fully understood by reading the following detailed description and embodiments in conjunction with the accompanying drawings. [Figure 1]FIG. 1 illustrates a perspective view of an apparatus for recycling sulfuric acid according to some embodiments. [Figure 2] 1 illustrates multiple vessels connected in series in some embodiments. [Figure 3] 2 shows a cross-sectional view of the bracket, infrared lamp, and ultraviolet lamp in the apparatus for recycling sulfuric acid of FIG. 1 along the cross section a-a'. [Figure 4] 2 shows a cross-sectional view of the arrangement of infrared and ultraviolet lamps in the apparatus for recycling sulfuric acid of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0028] In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, it will be apparent that one or more embodiments may be practiced without these specific details. Also, for purposes of simplicity in the drawings, well-known structures and devices are schematically shown.

[0029] One embodiment of the present disclosure provides an apparatus 100 for recycling sulfuric acid, as shown in FIG. 1. The apparatus 100 includes a container 101 having an interior space. In some embodiments, the container 101 is made of poly(tetrafluoroethene) (PTFE) or other suitable material. PTFE is resistant to acid corrosion and heat and has a specific reflectance angle for infrared and ultraviolet light, which is advantageous for liquid processing, as described below. The container 101 in FIG. 1 is cylindrical, but is not limited thereto. Those skilled in the art can adopt any reasonable container shape without departing from the scope of the present disclosure. For example, the cross section of the container 101 may be not only circular, but also square, rectangular, hexagonal, oval, or any other shape, as long as it is convenient for installation and operation. The volume of the container 101 may be, but is not limited to, 1 L to 20 L. If the volume of the container 101 is too small, an insufficient amount of liquid can be processed within a certain period of time. If the volume of the container 101 is too large, assembly and cleaning may be difficult.

[0030] The apparatus 100 also includes an inlet 103 located on a first side of the vessel 101 for introducing a liquid containing sulfuric acid and hydrogen peroxide. The liquid can be introduced into the vessel 101 through the inlet 103 via a pump. The inlet 103 can be connected via a conduit to a process chamber (e.g., an etching chamber or a cleaning chamber, not shown) that produces the liquid. Typically, the liquid produced by the process chamber may contain a small amount of solid impurities. The solid impurities can be removed using a filtration screen. The liquid is then introduced into the vessel 101. The conduit connecting the process chamber and the inlet 103 can be made of PTFE or polypropylene (PP), depending on the temperature of the liquid produced by the process chamber. If the temperature of the liquid is high (e.g., higher than 80°C), the conduit can be made of heat-resistant PTFE. If the temperature of the liquid is low (e.g., room temperature), the conduit can be made of PP, which can reduce costs.

[0031] The apparatus 100 also includes an outlet 105 located on the second side of the vessel 101 for discharging the treated liquid from the vessel 101, with the first side facing the second side. The outlet 105 may be connected to a collection tank (not shown) or to the inlet 103 of another apparatus 100. For example, as shown in FIG. 2, multiple apparatuses 100 may be connected in series, with the outlet 105 of each apparatus 100 connected to the inlet 103 of the next apparatus 100 via a conduit. This increases the amount of liquid that can be treated per unit time. Using multiple apparatuses 100 with small volumes connected in series (rather than a single apparatus with a large volume) is advantageous for cleaning and maintenance in actual use. For example, after replacing one of the multiple apparatuses 100 connected in series with a new apparatus 100, liquid can continue to be treated, and the replaced apparatus 100 can be cleaned and maintained at the same time. In contrast, liquid treatment must be stopped when cleaning and maintaining a single apparatus with a large volume. Even if a separate single device with a larger volume is prepared as a backup, the cost of assembling and disassembling it is still higher than that of the small volume device 100 connected in series. When the apparatus 100 is installed, for example, the first side is the upper side of the container 101, and the second side is the lower side of the container 101. The inlet 103 is preferably located lower than the outlet 105. The inlet 103 is preferably located near the lower side of the container 101, and the outlet 105 is preferably located near the upper side of the container 101. The liquid flowing into the container 101 from the inlet 103 located on the lower side flows toward the outlet 105 located on the upper side, where infrared and ultraviolet rays are used to promote the decomposition of hydrogen peroxide in the liquid into water and oxygen. The oxygen is discharged outside the apparatus 100 through an air hole located in the upper lid. The liquid treated in the container 101 is discharged outside the apparatus 100 through the outlet 105 located on the upper side. The outlet 105 may be fluidly connected to the inlet 103 of another apparatus 100 so that the treated liquid can be further treated by the other apparatus 100.

[0032] The apparatus 100 also includes an infrared lamp 107 located within the interior space of the vessel 101 and in contact with the liquid. Note that the efficiency of the infrared lamp 107 may be increased because the infrared lamp 107 is not mounted on the sidewall of the vessel 101. The tube of the infrared lamp 107 is made of quartz, which avoids the problem of acid corrosion of the liquid.

[0033] The apparatus 100 also includes an ultraviolet lamp 109 located within the interior space of the vessel 101 and in contact with the liquid. Note that the ultraviolet lamp 109 is not mounted on the sidewall of the vessel 101, which may increase the efficiency of the ultraviolet lamp 109. The tube of the ultraviolet lamp 109 is made of quartz, which avoids the problem of acid corrosion of the liquid. Note that the volume of the liquid tends not to be higher than the outlet 105, as an excessively high volume of the liquid will negatively affect the lifespan of the infrared lamp 107 and the ultraviolet lamp 109.

[0034] The apparatus 100 also includes a bracket 111 located in the interior space of the vessel 101 for connecting the infrared lamp 107 and the ultraviolet lamp 109. The structure of the bracket 111 is shown in the cross-sectional view of FIG. 3. FIG. 3 shows a cross-sectional view of the bracket 111, the infrared lamp 107, and the ultraviolet lamp 109 in the apparatus 100 for recycling sulfuric acid of FIG. 1 along the cross section a-a'. In FIG. 3, the bracket 111 has a cross shape within a circular frame to increase the degree of support, and the infrared lamp 107 and the ultraviolet lamp 109 are located at the end points of the cross shape, respectively. It should be understood that FIG. 3 is merely an example and does not limit the scope of the present disclosure. Alternatively, the frame of the bracket 111 may have another shape, such as a square, a hexagon, or another suitable shape, and the cross shape may be changed to another pattern, such as a star (e.g., *). In some embodiments, the brackets 111 may be spaced apart to provide a higher degree of support, and the spacing between adjacent brackets 111 and the pattern of the brackets 111 may be the same or different. Taking Fig. 3 as an example, the pattern of the brackets 111 has a turbulent effect that helps to uniformly mix the liquid flowing from the inlet 103 to the outlet 105. In addition, as shown in Fig. 1, the sidewall of the container 101 may be flat, or may have a specific texture (not shown) to further enhance the turbulent effect.

[0035] 1, the apparatus 100 also includes a lid 115 that covers the top of the container 101 and has an air vent 117 that can be connected to an exhaust system (not shown). The lamp bases of the infrared lamp 107 and the ultraviolet lamp 109 protrude from the lid 115 and connect to a power source, and brackets 119 may optionally be disposed on the lid 115 to support the ends of the infrared lamp 107 and the ultraviolet lamp 109.

[0036] In some embodiments, infrared light emitted from the infrared lamp 107 and ultraviolet light emitted from the ultraviolet lamp 109 decompose the hydrogen peroxide in the liquid into water and oxygen, with the infrared light heating the liquid and the oxygen being expelled through the air vent 117. The liquid is preferably heated to 90°C to 130°C. If the liquid temperature is too low, the hydrogen peroxide decomposition efficiency will be insufficient. If the liquid temperature is too high, a large amount of oxygen will be generated quickly and easily out of control. The infrared light not only heats the liquid, but also promotes the ultraviolet light to decompose the hydrogen peroxide. If the infrared lamp 107 is not used (for example, if only the ultraviolet lamp 109 is used and the liquid is heated by a separate heating device such as a hot plate), the effectiveness of decomposing the hydrogen peroxide will be reduced.

[0037] The sulfuric acid recycling apparatus 100 shown in FIG. 2 may further include a three-way valve 113 connected to the outlet 105 and used to discharge oxygen. The three-way valve 113 may be disposed between the outlet 105 of the container 101 and a collection tank (not shown) or between the outlet 105 of the container 101 and the inlet 103 of the next container 101. Oxygen generated by decomposing hydrogen peroxide can be discharged through the air vent 117 and the three-way valve 113. The oxygen does not accumulate in the container 101 and does not adversely affect the liquid processing step. The three-way valve 113 may also be connected to the outlet 105 of the container 101 and the inlet 103 of the next container 101 (or a collection tank) via a conduit. In addition, the three-way valve 113 may be connected to an exhaust device (not shown) like the air vent 117.

[0038] In some embodiments, the wavelength of the infrared light is 1500 nm to 6500 nm, which corresponds to the wavelength of the main absorption peak of hydrogen peroxide, such as 2800 nm to 2900 nm, 3500 nm to 3600 nm, and 6000 nm to 6500 nm. If the wavelength of the infrared light is not within the above range, the decomposition effect of hydrogen peroxide cannot be effectively enhanced.

[0039] In some embodiments, the wavelength of the ultraviolet light is 230 nm to 275 nm. If the wavelength of the ultraviolet light is not within the above range, hydrogen peroxide cannot be effectively decomposed.

[0040] In some embodiments, the energy density of each of the infrared and ultraviolet light is 0.1 W / cm 2 to 16W / cm 2 If the energy density of the infrared or ultraviolet light is too low, hydrogen peroxide cannot be effectively decomposed, whereas if the energy density of the infrared or ultraviolet light is too high, it becomes difficult to control the reaction temperature, causing sulfuric acid or hydrogen peroxide to boil, increasing the risk of operation.

[0041] In some embodiments, the energy density ratio of infrared and ultraviolet light is 4:1 to 20:1. If the ratio is too low, the reaction rate cannot be increased, resulting in a decrease in the treatment effect. If the ratio is too high, it becomes difficult to control the reaction temperature, causing sulfuric acid or hydrogen peroxide to boil, increasing the risk of operation.

[0042] In some embodiments, the apparatus further includes another infrared lamp 107 and another ultraviolet lamp 109, where the ratio of the total cross-sectional area of ​​the infrared lamp 107 to the cross-sectional area of ​​the vessel 101 is 1:100 to 5:100, and the ratio of the total cross-sectional area of ​​the ultraviolet lamp 109 to the cross-sectional area of ​​the vessel 101 is 1:100 to 5:100. If the total cross-sectional area of ​​the infrared lamp 107 is too small, the heating time will be too long and the desired reaction temperature will not be reached. If the total cross-sectional area of ​​the infrared lamp 107 is too large, it will be difficult to control the reaction temperature, and sulfuric acid or hydrogen peroxide will boil, increasing the risk of operation.

[0043] In some embodiments, as shown in FIG. 4 , the infrared lamps 107 are arranged in a cross section of the vessel 101 to form a first circle, and the ultraviolet lamps 109 are arranged in a cross section of the vessel 101 to form a second circle, the first and second circles being concentric, and the diameter of the first circle being larger than the diameter of the second circle. FIG. 4 shows a cross section of the arrangement of the infrared lamps and ultraviolet lamps in the apparatus for recycling sulfuric acid of FIG. 1 . It should be understood that FIG. 4 only shows the cross section of the infrared lamps 107 and the ultraviolet lamps (e.g., bracket 111 is not shown in this cross section). In some embodiments, bracket 111 may be disposed between the infrared lamps 107 and the ultraviolet lamps 109 and fixed in the vessel 101. FIG. 4 is for illustrative purposes only, and does not limit the scope of the present disclosure. Those skilled in the art can arrange multiple infrared lamps 107 and multiple ultraviolet lamps 109 in any manner. For example, the infrared lamps 107 and the ultraviolet lamps 109 may be arranged in a staggered and circular pattern. Regardless of how the infrared lamps 107 and the ultraviolet lamps 109 are arranged, the goal is to achieve the greatest and most uniform infrared and ultraviolet distribution effect with the least energy consumption, which allows the infrared and ultraviolet rays to decompose the hydrogen peroxide in the liquid and allows the infrared rays to heat the liquid.

[0044] In some embodiments, the flow rate of the liquid introduced through the inlet is between 0.5 m / hr and 3 m / hr. If the flow rate of the liquid introduced is too fast, the effect of decomposing hydrogen peroxide will be insufficient. If the flow rate of the liquid introduced is too slow, the uniformity of the liquid will be poor, and the effect of decomposing hydrogen peroxide will be reduced.

[0045] In some embodiments, the sulfuric acid concentration of the liquid is between 50 wt% and 70 wt%. The sulfuric acid is substantially unaffected by the above steps. However, due to the decomposition of hydrogen peroxide to form water and oxygen, the sulfuric acid concentration in the treated liquid will be slightly reduced (e.g., diluted by the water produced by decomposing the hydrogen peroxide).

[0046] In some embodiments, the hydrogen peroxide concentration of the liquid is 10,000 mg / L to 60,000 mg / L, and the hydrogen peroxide concentration of the treated liquid is 50 mg / L or less. The concentration of hydrogen peroxide in the treated liquid may be 40 mg / L or less, 30 mg / L or less, 10 mg / L or less, or even below the detection limit of the meter. In some embodiments, the treated liquid contains a high concentration of sulfuric acid and very low (or even non-existent) concentrations of hydrogen peroxide, allowing it to be used in relatively non-precise industries without further purification. In addition, because the method does not add any auxiliary agents (e.g., hydrochloric acid) to the liquid, the treated liquid is free of any other auxiliary agents and consists essentially of water and sulfuric acid (and small amounts of hydrogen peroxide, if present).

[0047] In some embodiments, a method for recycling sulfuric acid may include preparing a liquid in a container, the liquid containing sulfuric acid and hydrogen peroxide. The container may be the container 101 of the apparatus 100 described above or a separate container. Subsequently, the hydrogen peroxide in the liquid is decomposed into water and oxygen using infrared and ultraviolet light, and the liquid is heated to 90°C to 130°C by the infrared light. Finally, the treated liquid is collected. The wavelengths and energy densities of the infrared and ultraviolet light, as well as the sulfuric acid and hydrogen peroxide concentrations in the liquid and the treated liquid, are similar to those described above and will not be repeated here. Therefore, the present disclosure provides a method and apparatus for recycling sulfuric acid that can decompose hydrogen peroxide in the liquid without adding any additives and effectively recycle the sulfuric acid. Compared to conventional methods that add additives, the method of the present disclosure can avoid the generation of harmful gases (e.g., chlorine gas or NOx) in the reaction process and damage to the processing equipment and related piping. Furthermore, the recycled sulfuric acid recycled in the present disclosure without adding additives has high purity and can be directly used in other industries, such as the printed circuit board industry. Compared with the method using only ultraviolet light, the present disclosure combines ultraviolet light and infrared light, which can effectively increase the reaction rate (e.g., the decomposition efficiency of hydrogen peroxide is high in the same treatment time). The method for recycling sulfuric acid is preferably carried out using the apparatus according to this embodiment.

[0048]

[0023] In the following, exemplary embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand. The concept of the present invention is not limited to the exemplary embodiments shown herein, but may be embodied in various forms. For clarity, descriptions of known parts will be omitted, and similar reference numerals will denote similar components throughout. [Example]

[0049] In the following examples, the concentration of hydrogen peroxide was analyzed according to the method disclosed by Steller (Spectrophotometric Determination of Hydrogen Peroxide Using Potassium (IV) Oxalate,” Analyst, Oct. 105, 950-954 (1980)). For example, acidic solutions of potassium titanium oxalate (0.05 M potassium titanium oxalate in 3 M H2SO4 solution) were mixed with different amounts of hydrogen peroxide to form different amounts of yellow complexes of tetravalent titanium. These were analyzed spectrophotometrically, and the absorbance at 400 nm was measured, followed by calibration of the calibration curve. For analysis, 5 mL of the acidic potassium titanium oxalate solution, an appropriate amount of sample, and deionized water were mixed uniformly, and the absorbance at 400 nm of the mixture was measured. The concentration of hydrogen peroxide in the sample could be calculated from the absorbance and the calibration curve.

[0050] Comparative Example 1 A 200 mL mixture of sulfuric acid and hydrogen peroxide containing 60 wt% sulfuric acid and 50,000 mg / L hydrogen peroxide was prepared. The mixture was heated to 90°C on a hot plate, and the hydrogen peroxide in the mixture was monitored to determine the decomposition reaction rate (0.0017 min -1 ), and the decomposition efficiency of hydrogen peroxide (5%) after 1 hour of treatment were calculated.

[0051] Comparative Example 2 200 mL of a mixture of sulfuric acid and hydrogen peroxide containing 60 wt% sulfuric acid and 50,000 mg / L of hydrogen peroxide was prepared. The mixture was heated to 90°C on a hot plate and irradiated with ultraviolet light (254 nm / 0.22 W / cm). 2 ) and tracked the hydrogen peroxide in the mixture to determine the decomposition reaction rate (0.0021 min -1 ), and the decomposition efficiency of hydrogen peroxide (14%) after 1 hour of treatment were calculated.

[0052] Comparative Example 3 A 200 mL mixture of sulfuric acid and hydrogen peroxide containing 60 wt% sulfuric acid and 50,000 mg / L of hydrogen peroxide was prepared. The mixture was then irradiated with infrared light (1500 nm to 6500 nm / 4.21 W / cm). 2 ), which heated the mixture to 90°C. The hydrogen peroxide in the mixture was monitored to determine the decomposition rate (0.0026 min -1 ), and the decomposition efficiency of hydrogen peroxide (18%) after 1 hour of treatment were calculated.

[0053] Comparative Example 4 A 200 mL mixture of sulfuric acid and hydrogen peroxide containing 60 wt% sulfuric acid and 50,000 mg / L of hydrogen peroxide was prepared. The mixture was then irradiated with infrared light (1500 nm to 6500 nm / 4.21 W / cm). 2 ), which heated the mixture to 105°C. The hydrogen peroxide in the mixture was monitored to determine the decomposition rate (0.0039 min -1 ), and the decomposition efficiency of hydrogen peroxide (28%) after 1 hour of treatment were calculated.

[0054] Comparative Example 5 A 200 mL mixture of sulfuric acid and hydrogen peroxide containing 60 wt% sulfuric acid and 50,000 mg / L of hydrogen peroxide was prepared. The mixture was then irradiated with infrared light (1500 nm to 6500 nm / 4.21 W / cm). 2 ), which heated the mixture to 120°C. The hydrogen peroxide in the mixture was monitored to determine the decomposition reaction rate (0.0073 min -1 ), and the decomposition efficiency of hydrogen peroxide (46%) after 1 hour of treatment were calculated.

[0055] Comparative Example 6 A 200 mL mixture of sulfuric acid and hydrogen peroxide containing 60 wt% sulfuric acid and 55,000 mg / L of hydrogen peroxide was prepared. The mixture was then irradiated with infrared light (1500 nm to 6500 nm / 4.21 W / cm). 2 ), which heated the mixture to 130°C. The hydrogen peroxide in the mixture was monitored to determine the decomposition rate (0.0173 min -1 ), and the decomposition efficiency of hydrogen peroxide (68%) after 1 h of treatment were calculated.

[0056] Example 1 A mixed solution of sulfuric acid and hydrogen peroxide containing 60 wt% sulfuric acid and 47,500 mg / L of hydrogen peroxide was prepared. The mixed solution was irradiated with infrared light (1,500 nm to 6,500 nm / 4.21 W / cm 2 ) and ultraviolet light (254 nm / 0.22 W / cm 2 ), which heated the mixture to 130°C. The hydrogen peroxide in the mixture was monitored to determine the decomposition rate (0.0239 min -1 The decomposition efficiency of hydrogen peroxide after 1 hour of treatment (approximately 84%) was calculated. The sulfuric acid concentration of the treated mixture was 60 wt% and the hydrogen peroxide concentration was 50 mg / L.

[0057] Example 2 A sulfuric acid and hydrogen peroxide waste solution containing 76 wt% sulfuric acid and 6250 mg / L of hydrogen peroxide was generated at the factory. The mixture was then subjected to infrared irradiation (1500 nm to 6500 nm / 4.21 W / cm 2 ) and ultraviolet light (254 nm / 0.22 W / cm 2 ), which heated the mixture to 130°C. The hydrogen peroxide in the mixture was monitored to determine the decomposition rate (0.0228 min -1 The decomposition efficiency of hydrogen peroxide after 1 hour of treatment (approximately 82%) was calculated. The sulfuric acid concentration of the treated mixture was 76 wt% and the hydrogen peroxide concentration was 50 mg / L.

[0058] Example 3 See Figure 1. A cylindrical container with a diameter of 40 cm and a length of 180 cm was selected for use. Four infrared lamps (diameter 3 cm, length 180 cm, emission wavelength 1500 nm to 6500 nm, energy density 9.27 W / cm) were installed. 2 ) and three ultraviolet lamps (diameter 3 cm, length 180 cm, emission wavelength 253.7 nm, energy density 1.02 W / cm 2 ) was placed in the container. The arrangement of the infrared lamp and ultraviolet lamp can be seen in Figure 4.

[0059] A mixture of sulfuric acid and hydrogen peroxide containing 60 wt% sulfuric acid and 47,500 mg / L of hydrogen peroxide was prepared. The mixture was introduced into the vessel through an inlet at the bottom. The flow rate of the mixture was 2.59 m / h. The mixture was irradiated with infrared and ultraviolet light and heated to 130°C. The air hole in the lid was connected to an exhaust system to exhaust the oxygen produced. The treated mixture was passed through a three-way valve (used to exhaust the oxygen in the mixture) and introduced into the inlet at the bottom of the vessel. The treated mixture was circulated and returned to the vessel. The hydrogen peroxide in the mixture was monitored to determine its decomposition reaction rate (0.024 min -1 The decomposition efficiency of hydrogen peroxide after 1 hour of treatment (approximately 85%) was calculated. The sulfuric acid concentration of the treated mixture was 60 wt% and the hydrogen peroxide concentration was 50 mg / L.

[0060] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed methods and materials. It is intended that the specification and various embodiments be considered as exemplary only, with the true scope of the disclosure being indicated by the following claims and their equivalents. (Addendum) (Appendix 1) 1. An apparatus for recycling sulfuric acid, comprising: a container having an interior space; an inlet located on a first side of the vessel for introducing a liquid containing sulfuric acid and hydrogen peroxide; an outlet located on a second side of the vessel for discharging treated liquid from the vessel, the first side and the second side being opposed; an infrared lamp located within the interior space of the container and in contact with the liquid; an ultraviolet lamp located within the interior space of the container and in contact with the liquid; a bracket located in the internal space of the container and connecting the infrared lamp and the ultraviolet lamp; a lid covering the top of the container and having an air hole; Including, The infrared light emitted from the infrared lamp and the ultraviolet light emitted from the ultraviolet lamp decompose the hydrogen peroxide in the liquid into water and oxygen, the infrared light heats the liquid, and the oxygen is discharged through the air hole. (Appendix 2) 10. The apparatus of claim 1, further comprising a three-way valve connected to the outlet for exhausting the oxygen. (Appendix 3) 2. The device of claim 1, wherein the infrared light has a wavelength of 1500 nm to 6500 nm. (Appendix 4) 2. The device of claim 1, wherein the ultraviolet light has a wavelength of 230 nm to 275 nm. (Appendix 5) The energy density of each of the infrared rays and the ultraviolet rays is 0.1 W / cm 2 to 16W / cm 2 2. The apparatus of claim 1, (Appendix 6) 2. The device of claim 1, wherein the ratio of energy densities of the infrared light to the ultraviolet light is between 4:1 and 20:1. (Appendix 7) 10. The apparatus of claim 1, further comprising other infrared lamps and other ultraviolet lamps, wherein the ratio of the total cross-sectional area of ​​the infrared lamps to the cross-sectional area of ​​the container is 1:100 to 5:100, and the ratio of the total cross-sectional area of ​​the ultraviolet lamps to the cross-sectional area of ​​the container is 1:100 to 5:100. (Appendix 8) 8. The apparatus of claim 7, wherein the infrared lamps are arranged in a cross-section of the container to form a first circle and the ultraviolet lamps are arranged in a cross-section of the container to form a second circle, the first and second circles being concentric, and the diameter of the first circle being greater than the diameter of the second circle. (Appendix 9) 10. The apparatus of claim 1, wherein the flow rate of the liquid introduced through the inlet is between 0.5 m / hr and 3 m / hr. (Appendix 10) 2. The apparatus of claim 1, wherein the liquid has a sulfuric acid concentration of 50 wt% to 70 wt%. (Appendix 11) 10. The apparatus of claim 1, wherein the hydrogen peroxide concentration of the liquid is between 10,000 mg / L and 60,000 mg / L and the hydrogen peroxide concentration of the treated liquid is 50 mg / L or less. (Appendix 12) 2. The device of claim 1, wherein the sidewall of the container has an uneven structure. (Appendix 13) 1. A method for recycling sulfuric acid, comprising: providing a liquid containing sulfuric acid and hydrogen peroxide in a container; decomposing the hydrogen peroxide in the liquid into water and oxygen using infrared and ultraviolet light, and heating the liquid to 90°C to 130°C by the infrared light; collecting the treated liquid; A method comprising: (Appendix 14) 14. The method of claim 13, performed using the device of claim 1. [Explanation of symbols]

[0061] a-a' cross section 100...device 101...container 103...Entrance 105...Exit 107 Infrared lamp 109 Ultraviolet lamp 111,119···Bracket 113... Three-way valve 115...lid 117 Air vent

Claims

1. 1. An apparatus for recycling sulfuric acid, comprising: a container having an interior space; an inlet located on a first side of the vessel for introducing a liquid containing sulfuric acid and hydrogen peroxide; an outlet located on a second side of the vessel for discharging treated liquid from the vessel, the first side and the second side being opposed; an infrared lamp located within the interior space of the container and in contact with the liquid; an ultraviolet lamp located within the interior space of the container and in contact with the liquid; a bracket located in the internal space of the container and connecting the infrared lamp and the ultraviolet lamp; a lid covering the top of the container and having an air hole; Including, The infrared light emitted from the infrared lamp and the ultraviolet light emitted from the ultraviolet lamp decompose the hydrogen peroxide in the liquid into water and oxygen, the infrared light heats the liquid, and the oxygen is discharged through the air hole.

2. 10. The apparatus of claim 1, further comprising a three-way valve connected to said outlet for exhausting said oxygen.

3. 2. The device of claim 1, wherein the infrared light has a wavelength of 1500 nm to 6500 nm.

4. 2. The device of claim 1, wherein the ultraviolet light has a wavelength of 230 nm to 275 nm.

5. The energy density of each of the infrared rays and the ultraviolet rays is 0.1 W / cm ２ to 16 W / cm ２ 2. The device of claim 1, wherein:

6. 2. The apparatus of claim 1, wherein the energy density ratio of the infrared light to the ultraviolet light is between 4:1 and 20:

1.

7. 2. The apparatus of claim 1, further comprising other infrared lamps and other ultraviolet lamps, wherein the ratio of the total cross-sectional area of ​​the infrared lamps to the cross-sectional area of ​​the container is 1:100 to 5:100, and the ratio of the total cross-sectional area of ​​the ultraviolet lamps to the cross-sectional area of ​​the container is 1:100 to 5:

100.

8. 8. The apparatus of claim 7, wherein the infrared lamps are arranged in a cross section of the container to form a first circle, and the ultraviolet lamps are arranged in a cross section of the container to form a second circle, the first and second circles being concentric, and the diameter of the first circle being greater than the diameter of the second circle.

9. The device of claim 1 , wherein the sidewall of the container has a textured structure.

10. 1. A method for recycling sulfuric acid, comprising: providing a liquid containing sulfuric acid and hydrogen peroxide in a container; decomposing the hydrogen peroxide in the liquid into water and oxygen using infrared and ultraviolet rays, and heating the liquid to a temperature of 90°C or higher and 130°C or lower by the infrared rays; collecting the treated liquid; A method comprising:

11. 11. The method of claim 10, implemented using the apparatus of claim 1.

12. The method of claim 10, wherein the sulfuric acid concentration of the liquid is between 50 wt% and 70 wt%.

13. The method described in claim 10, wherein the hydrogen peroxide concentration of the liquid is 10,000 mg / L to 60,000 mg / L and the hydrogen peroxide concentration of the treated liquid is 50 mg / L or less.

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