Method for removing organic matters from industrial waste salt and simultaneously realizing high-value conversion

Abstract

The application relates to a method for removing organic matters from industrial waste salt and simultaneously realizing high-value conversion, and belongs to the technical field of waste salt treatment and resource recycling. The method is based on cracking, cooling crystallization and gas recovery, and comprises the following steps: reacting industrial waste salt with a phosphorus source, removing organic matters under high-temperature conditions, simultaneously realizing a high-value conversion reaction, cooling to obtain sodium hexametaphosphate, and recovering gas and synthesizing valuable substances. In one aspect, the organic pollutants in the industrial waste salt are completely decomposed through high-temperature cracking, and the industrial waste salt is harmlessly treated. In another aspect, the inorganic components in the industrial waste salt react with the phosphorus source, sodium hexametaphosphate is generated and can be used as a washing aid and a mineral flotation agent, gas is recovered and valuable substances are synthesized, and the industrial waste salt is recycled and the low-value waste salt is high-value converted. The application provides a method for efficiently removing organic matters from industrial waste salt and simultaneously realizing high-value conversion, has a good industrial application prospect, and has remarkable economic and social values.

Description

Technical Field

[0001] This invention relates to the field of waste salt treatment and resource recycling technology, specifically to a method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion. Background Technology

[0002] Industrial waste salt is a solid hazardous waste containing one or more inorganic salts such as sodium chloride and sodium sulfate, and generally contains a large amount of recalcitrant organic matter. Industrial waste salt comes from a wide range of sources, mainly from coal chemical, pesticide, printing and dyeing, and fine chemical industries. Its composition is complex and its total volume is large, currently exceeding 20 million tons annually. It is difficult to treat and its disposal as hazardous waste is costly. Enterprises currently use temporary storage or mixed-use methods, which pose serious environmental hazards and waste resources. Therefore, industrial waste salt needs to be treated harmlessly and utilized as a resource.

[0003] Currently, common methods for treating waste salt include salt washing, adsorption, oxidation, and thermal treatment. However, methods like salt washing, adsorption, and oxidation often result in incomplete removal of organic pollutants. Thermal treatment, including incineration and pyrolysis, can efficiently remove organic matter, achieving the goal of rendering waste salt harmless. Compared to other methods, thermal treatment is more expensive, and the reuse value of purified sodium sulfate and sodium chloride may be lower than the treatment cost. It is possible to treat the inorganic components in waste salt simultaneously as a raw material, combining them with certain substances to achieve the simultaneous removal of organic matter and conversion into higher-value substances, thus achieving the goal of waste salt resource utilization and high-value conversion. Therefore, it is necessary to develop an efficient treatment process that simultaneously removes organic matter from waste salt and converts it into high-value components, realizing the harmless treatment, resource utilization, and high-value conversion of low-value waste salt in industrial waste salt. Summary of the Invention

[0004] The purpose of this invention is to provide a method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion. The method uses chloromethyl polystyrene resin or modified polystyrene resin to adsorb and remove calcium ion impurities from industrial wastewater containing sodium sulfate, initially obtaining sodium sulfate waste salt. The sodium sulfate waste salt is then reacted with ammonium dihydrogen phosphate to remove organic matter under high-temperature conditions, simultaneously achieving high-value conversion. After the reaction is completed, cooling is performed to obtain sodium hexametaphosphate with a high yield. Gases are recovered during the process, and valuable substances are synthesized. This method achieves both the removal of organic matter and high-value conversion of industrial waste salt, realizing the harmlessness and resource utilization of industrial waste salt.

[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0006] A method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion includes: first, stirring industrial wastewater containing sodium sulfate with an adsorption resin, filtering, and rotary evaporating to obtain sodium sulfate waste salt; then, reacting the sodium sulfate waste salt with a phosphorus source at high temperature, followed by rapid cooling and crystallization to obtain sodium hexametaphosphate, while simultaneously recovering the organic waste gas generated in the reaction and converting it into a valuable substance; the phosphorus source includes at least ammonium dihydrogen phosphate and / or phosphoric acid, the organic waste gas includes at least one of sulfur trioxide gas and ammonia gas, and the valuable substance includes ammonium sulfate or sulfuric acid; the adsorption resin includes chloromethyl polystyrene resin or modified polystyrene resin; the modified polystyrene resin has carbonyl groups and phenolic groups.

[0007] This invention uses chloromethyl polystyrene resin or modified polystyrene resin to adsorb and remove calcium ion impurities from industrial wastewater containing sodium sulfate, initially obtaining sodium sulfate waste salt; then the sodium sulfate waste salt is reacted with ammonium dihydrogen phosphate, removing organic matter under high temperature conditions, and simultaneously undergoing a high-value conversion reaction. After completion, cooling is performed to obtain sodium hexametaphosphate with a high yield. The process recovers gas and synthesizes valuable substances. The industrial waste salt achieves high-value conversion while removing organic matter, realizing the harmlessness and resource utilization of industrial waste salt.

[0008] Preferably, the ratio of sodium sulfate-containing industrial wastewater to adsorption resin is 1 mL: 0.005-0.01 g.

[0009] Preferably, the mass ratio of sodium sulfate waste salt to phosphorus source is 1:1-2.

[0010] Preferably, in the high-temperature reaction, the heating rate is 6-16℃ / min.

[0011] Preferably, in the high-temperature reaction, the reaction temperature is 500-800℃.

[0012] Preferably, in the high-temperature reaction, the reaction time is 0.4-2 hours.

[0013] Preferably, in the rapid cooling crystallization, the cooling rate is 4-100℃ / min.

[0014] Preferably, in the preparation of the modified polystyrene resin, chloromethyl polystyrene resin is first swollen in 1,2-dichloroethane, and then reacted with 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and 2,3,5,6-tetrafluorophenol to obtain the modified polystyrene resin. This invention reacts chloromethyl polystyrene resin with 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and 2,3,5,6-tetrafluorophenol, which helps to introduce phenolic hydroxyl and amino groups onto the chloromethyl polystyrene resin. The prepared modified polystyrene resin has good surface functionality and excellent adsorption performance, effectively adsorbing and removing calcium ion impurities from industrial wastewater containing sodium sulfate. This reduces the calcium ion content in the obtained sodium sulfate waste salt, reduces the impact of calcium ion impurities on the reaction of sodium sulfate waste salt with phosphorus source, effectively increases the yield of sodium hexametaphosphate generated in the reaction of sodium sulfate waste salt with phosphorus source, and achieves the harmlessness and resource utilization of industrial waste salt.

[0015] More preferably, the ratio of chloromethyl polystyrene resin to 1,2-dichloroethane is 1 g: 10-20 mL.

[0016] More preferably, the mass ratio of chloromethyl polystyrene resin to 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline is 1:0.02-0.1.

[0017] More preferably, the mass ratio of chloromethyl polystyrene resin to 2,3,5,6-tetrafluorophenol is 1:1-2.

[0018] Preferably, the preparation of the modified polystyrene resin specifically involves,

[0019] Weigh out chloromethyl polystyrene resin, add 1,2-dichloroethane to swell for 6-12 h, add 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and anhydrous ferric chloride and stir for 1-3 h, reflux at 70-90℃ for 10-15 h, add 2,3,5,6-tetrafluorophenol and tetrahydrofuran and stir for 5-20 min, react at 80-90℃ under nitrogen for 36-60 h, Soxhlet extract for 12-24 h, and freeze dry under vacuum to obtain modified polystyrene resin.

[0020] More preferably, the ratio of chloromethyl polystyrene resin to 1,2-dichloroethane is 1 g: 10-20 mL.

[0021] More preferably, the mass ratio of chloromethyl polystyrene resin to 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline is 1:0.02-0.1.

[0022] More preferably, the mass ratio of chloromethyl polystyrene resin to anhydrous ferric chloride is 1:0.1-0.5.

[0023] More preferably, the mass ratio of chloromethyl polystyrene resin to 2,3,5,6-tetrafluorophenol is 1:1-2.

[0024] More preferably, the volume ratio of 1,2-dichloroethane to tetrahydrofuran is 1:15.

[0025] Preferably, the preparation of the modified polystyrene resin specifically involves,

[0026] Chloromethyl polystyrene resin was weighed and swollen in 1,2-dichloroethane for 6-12 hours. Then, 2-methyl-3-(1-pyrrolylcarbonyl)aniline and anhydrous ferric chloride were added and stirred for 1-3 hours. The mixture was refluxed at 70-90°C for 10-15 hours. Next, 2,3-,5,6-tetrafluorophenol and tetrahydrofuran were added and stirred for 5-20 minutes. The mixture was reacted at 80-90°C under nitrogen for 36-60 hours. Then, 1,4-diisocyanate butane was added and the mixture was reacted at 110-130°C under nitrogen for 12-18 hours. The mixture was then subjected to Soxhlet extraction for 12-24 hours and freeze-dried under vacuum to obtain modified polystyrene resin. This invention further utilizes 1,4-diisocyanate butane to prepare modified polystyrene resin, which can further improve the surface functionality of the modified polystyrene resin and enhance its adsorption performance, thereby further improving the calcium ion removal rate and sodium hexametaphosphate yield.

[0027] More preferably, the ratio of chloromethyl polystyrene resin to 1,2-dichloroethane is 1 g: 10-20 mL.

[0028] More preferably, the mass ratio of chloromethyl polystyrene resin to 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline is 1:0.02-0.1.

[0029] More preferably, the mass ratio of chloromethyl polystyrene resin to anhydrous ferric chloride is 1:0.1-0.5.

[0030] More preferably, the mass ratio of chloromethyl polystyrene resin to 2,3,5,6-tetrafluorophenol is 1:1-2.

[0031] More preferably, the volume ratio of 1,2-dichloroethane to tetrahydrofuran is 1:15.

[0032] More preferably, the mass ratio of chloromethyl polystyrene resin to 1,4-diisocyanate butane is 1:0.5-1.

[0033] Preferably, a method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion specifically includes:

[0034] Add adsorption resin to industrial wastewater containing sodium sulfate and stir for 12-24 hours. Filter and retain the supernatant. Remove the solvent by rotary evaporation to obtain sodium sulfate waste salt. Mix the sodium sulfate waste salt with a phosphorus source evenly, raise the temperature to 500-800℃ at a rate of 6-16℃ / min, maintain for 0.4-2 hours, and then cool down at a rate of 4-100℃ / min to crystallize and form a glassy substance. After crushing, sodium hexametaphosphate is obtained.

[0035] More preferably, the phosphorus source is ammonium dihydrogen sulfate or phosphoric acid. When the phosphorus source is ammonium dihydrogen phosphate, the reaction between sodium sulfate and ammonium dihydrogen phosphate generates organic waste gas and water vapor. The organic waste gas includes sulfur trioxide gas and ammonia gas. The sulfur trioxide gas and ammonia gas are recovered, and the sulfur trioxide gas, ammonia, and water are reacted to generate ammonium sulfate. When the phosphorus source is phosphoric acid, the reaction between sodium sulfate and phosphoric acid generates sulfur trioxide gas and water vapor. The sulfur trioxide gas is recovered, and the sulfur trioxide gas and water are reacted to generate ammonium sulfate.

[0036] More preferably, the adsorbent resin includes aminomethyl polystyrene resin or modified polystyrene resin.

[0037] More preferably, the ratio of sodium sulfate-containing industrial wastewater to adsorption resin is 1 mL: 0.005-0.01 g.

[0038] More preferably, the mass ratio of sodium sulfate waste salt to phosphorus source is 1:1-2.

[0039] This invention utilizes chloromethyl polystyrene resin or modified polystyrene resin to adsorb and remove calcium ion impurities from industrial wastewater containing sodium sulfate, obtaining sodium sulfate waste salt. The sodium sulfate waste salt is then reacted with a phosphorus source at high temperature, resulting in the following beneficial effects: The invention uses adsorption resin to remove calcium ion impurities from sodium sulfate industrial wastewater, and the adsorption resin has a high calcium ion removal rate of 88.0-99.7%, thereby reducing the impact of calcium ion impurities on the reaction between sodium sulfate waste salt and the phosphorus source. The reaction of sodium sulfate waste salt with the phosphorus source yields a high-yield sodium hexametaphosphate, with a yield of 75.0-98.4%. The waste salt treated by this invention has an organic matter content of less than 15 mg / kg or meets the requirements for resource utilization of organic matter, achieving the harmless treatment of industrial waste salt and effectively solving the problems of high disposal costs and potential hazards caused by temporary storage of waste salt. This invention removes organic matter while simultaneously converting low-value waste salt into high-value products. During the process, gas is collected and effectively converted into valuable substances, achieving both processing and added value. The process is short, the equipment is simple, and the production cost is low. The sodium hexametaphosphate produced by this invention can be used in situ within factories or industrial parks, effectively realizing the resource utilization of industrial waste salt and generating good economic and environmental benefits. Attached Figure Description

[0040] Figure 1 This is the conversion process of Embodiment 1 of the present invention.

[0041] Figure 2 The graph shows the results of the burn-off rate.

[0042] Figure 3 The graph shows the results of organic matter removal rate. Detailed Implementation

[0043] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0044] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0045] Example 1:

[0046] A method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion includes,

[0047] In industrial wastewater containing sodium sulfate, chloromethyl polystyrene resin was added for adsorption and stirring for 12 hours. The supernatant was filtered and the solvent was removed by rotary evaporation to obtain sodium sulfate waste salt. The sodium sulfate waste salt was mixed evenly with a phosphorus source, and the temperature was raised to 550℃ at a rate of 10℃ / min and held for 1 hour. Then, the temperature was rapidly cooled at a rate of 16℃ / min to crystallize and form a glassy substance, which was then crushed to obtain sodium hexametaphosphate. When the phosphorus source was ammonium dihydrogen phosphate, organic waste gas and water vapor were generated during the reaction of sodium sulfate and ammonium dihydrogen phosphate. The organic waste gas included sulfur trioxide gas and ammonia gas. The sulfur trioxide gas and ammonia gas were recovered, and the sulfur trioxide gas, ammonia, and water were reacted to form ammonium sulfate. The ratio of sodium sulfate industrial wastewater to chloromethyl polystyrene resin was 1 mL: 0.01 g; the mass ratio of sodium sulfate waste salt to phosphorus source was 1: 1.55.

[0048] Example 2:

[0049] The difference between this embodiment and Embodiment 1 lies in the method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion.

[0050] A method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion involves replacing ammonium dihydrogen phosphate in the phosphorus source with phosphoric acid, generating sulfur trioxide gas and water vapor during the reaction of sodium sulfate with phosphoric acid, recovering the sulfur trioxide gas, and reacting the sulfur trioxide gas with water to generate ammonium sulfate. Other conditions are the same as in Example 1.

[0051] Example 3:

[0052] The difference between this embodiment and Embodiment 1 lies in the method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion.

[0053] A method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion, except that the chloromethyl polystyrene resin is replaced with the modified polystyrene resin prepared in this embodiment, and other conditions are the same as in Example 1.

[0054] The preparation of modified polystyrene resin includes,

[0055] Chloromethyl polystyrene resin was weighed and swollen in 1,2-dichloroethane for 8 hours. Then, 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and anhydrous ferric chloride were added and stirred for 2 hours. The mixture was refluxed at 80°C for 12 hours. Next, 2,3,5,6-tetrafluorophenol and tetrahydrofuran were added and stirred for 10 minutes. The mixture was reacted at 85°C under nitrogen for 48 hours, followed by Soxhlet extraction for 12 hours. The mixture was then freeze-dried under vacuum to obtain modified polystyrene resin. The mass ratio of chloromethyl polystyrene resin to 1,2-dichloroethane was 1 g:10 mL; the mass ratio of chloromethyl polystyrene resin to 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline was 1:0.1; the mass ratio of chloromethyl polystyrene resin to anhydrous ferric chloride was 1:0.25; the mass ratio of chloromethyl polystyrene resin to 2,3,5,6-tetrafluorophenol was 1:1.2; and the volume ratio of 1,2-dichloroethane to tetrahydrofuran was 1:15.

[0056] Example 4:

[0057] The difference between this embodiment and embodiment 3 is that it is a method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion.

[0058] A method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion, except that the ratio of sodium sulfate-containing industrial wastewater to modified polystyrene resin is changed to 1 mL: 0.005 g, all other conditions are the same as in Example 2.

[0059] Example 5:

[0060] The difference between this embodiment and Embodiment 1 lies in the method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion.

[0061] A method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion, except that the chloromethyl polystyrene resin is replaced with the modified polystyrene resin prepared in this embodiment, and other conditions are the same as in Example 1.

[0062] The preparation of modified polystyrene resin includes,

[0063] Chloromethyl polystyrene resin was weighed, swollen in 1,2-dichloroethane for 8 hours, then 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and anhydrous ferric chloride were added and stirred for 2 hours. The mixture was refluxed at 80°C for 12 hours, then 2,3,5,6-tetrafluorophenol and tetrahydrofuran were added and stirred for 10 minutes. The mixture was reacted at 85°C under nitrogen for 48 hours, then 1,4-diisocyanate butane was added and reacted at 120°C under nitrogen for 14 hours. The mixture was then extracted with Soxhlet for 12 hours and freeze-dried under vacuum to obtain modified polystyrene resin. The mass ratio of chloromethyl polystyrene resin to 1,2-dichloroethane is 1 g: 10 mL; the mass ratio of chloromethyl polystyrene resin to 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline is 1:0.1; the mass ratio of chloromethyl polystyrene resin to anhydrous ferric chloride is 1:0.25; the mass ratio of chloromethyl polystyrene resin to 2,3,5,6-tetrafluorophenol is 1:1.2; the volume ratio of 1,2-dichloroethane to tetrahydrofuran is 1:15; and the mass ratio of chloromethyl polystyrene resin to 1,4-diisocyanate butane is 1:0.7.

[0064] Example 6:

[0065] The difference between this embodiment and embodiment 5 is that it is a method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion.

[0066] A method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion, except that the ratio of sodium sulfate-containing industrial wastewater to modified polystyrene resin is changed to 1 mL: 0.005 g, all other conditions are the same as in Example 4.

[0067] Comparative Example 1:

[0068] The difference between this comparative example and Example 3 lies in the preparation of the modified polystyrene resin.

[0069] The modified polystyrene resin was prepared under the same conditions as in Example 3, except that 2,3,5,6-tetrafluorophenol was not added.

[0070] Comparative Example 2:

[0071] The difference between this comparative example and Example 3 lies in the preparation of the modified polystyrene resin.

[0072] The modified polystyrene resin was prepared under the same conditions as in Example 3, except that 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline was not added.

[0073] Comparative Example 3:

[0074] The difference between this comparative example and Example 5 lies in the preparation of the modified polystyrene resin.

[0075] The modified polystyrene resin was prepared under the same conditions as in Example 5, except that 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and 2,3,5,6-tetrafluorophenol were not added.

[0076] Experimental example:

[0077] 1. Content of inactive phosphates

[0078] Following the methods in Examples 1-2, industrial wastewater containing sodium sulfate was converted into sodium hexametaphosphate. Based on the industry standard for industrial sodium hexametaphosphate HG / T 2519—2017, the content of inactive phosphate in the sodium hexametaphosphate obtained in Examples 1-2 was analyzed.

[0079] Figure 1 The conversion process of Example 1 of this invention involves first mixing industrial wastewater containing sodium sulfate with an adsorption resin to adsorb organic matter, then removing the solvent by rotary evaporation to obtain sodium sulfate waste salt. Next, the sodium sulfate waste salt is mixed with a phosphorus source and fed into a pyrolysis furnace. Under high-temperature conditions, it undergoes metathesis reaction, dehydration, and polymerization reaction. After the reaction is completed, it is rapidly cooled to crystallize, ground, and crushed to obtain sodium hexametaphosphate. During the reaction, gases are recovered and valuable substances are synthesized. The sodium hexametaphosphate generated in Example 1 of this invention has a non-reactive phosphate content of 4%, which is lower than the limit specified in industry standard HG / T 2519—2017. The sodium hexametaphosphate generated in Example 2 of this invention has a non-reactive phosphate content of 6%, which is also lower than the limit specified in industry standard HG / T 2519—2017. This indicates that the content of non-active phosphate in the sodium hexametaphosphate obtained by the methods of Examples 1 and 2 of the present invention meets the limits of industry standard HG / T2519-2017. It can be used as a detergent, water softener, cleaning agent, corrosion inhibitor, flotation agent, dispersant, rust remover, cement hardener, etc. It can also be used as a scale inhibitor in membrane treatment processes such as electrodialysis, reverse osmosis, and nanofiltration during near-zero discharge of industrial wastewater.

[0080] 2. Loss on ignition

[0081] Organic matter was removed from industrial wastewater containing sodium sulfate according to the methods in Examples 1-2, and sodium sulfate waste salt was extracted; then, the sodium sulfate waste salt was reacted with a phosphorus source to generate a solid product. A control group was set up, in which the conditions were the same as in Example 1, except that the sodium sulfate waste salt was replaced with pure sodium sulfate product.

[0082] Before the reaction of waste sodium sulfate or pure sodium sulfate product with the phosphorus source, the total mass of the waste sodium sulfate or pure sodium sulfate product and the phosphorus source was measured and recorded as G1; after the reaction of waste sodium sulfate or pure sodium sulfate product with the phosphorus source, the total mass of the solid products generated by the reaction was measured and recorded as G2. The loss on ignition rate of the control group, Example 1, and Example 2 was calculated. Loss on ignition rate (%) = (G1-G2) / G1×100%.

[0083] Figure 2 The graph shows the results of the loss on ignition, with S1 representing the loss on ignition rate of the control group, S2 representing the loss on ignition rate of Example 1, and S3 representing the loss on ignition rate of Example 2. This demonstrates that the process conditions of the present invention enable the sodium sulfate waste salt to react completely with the phosphorus source.

[0084] 3. Organic matter removal rate

[0085] The sodium sulfate waste salt from Example 1 was collected, and the total organic carbon content in the solid products generated at different high-temperature temperatures was determined using a total organic carbon analyzer, denoted as X1. A control group and an experimental group were set up. In the control group, the sodium sulfate waste salt was calcined at high temperature for 1 hour, followed by rapid cooling crystallization to obtain the solid product. In the experimental group, the sodium sulfate waste salt and ammonium dihydrogen phosphate were calcined at high temperature for 1 hour, followed by rapid cooling crystallization to obtain the solid product. The high-temperature temperatures were 300℃, 400℃, 500℃, and 600℃. The total organic carbon content in the solid products generated at different high-temperature temperatures was determined using a total organic carbon analyzer, denoted as X2. Organic matter removal rate (%) = (X1-X2) / X1×100%.

[0086] Figure 3 The graph shows the results of organic matter removal rates, with S1 representing the organic matter removal rate of the control group and S2 representing the organic matter removal rate of the experimental group. At 300℃, the organic matter removal rate of the control group was 56%, while that of the experimental group was 88%. This indicates that the high-temperature reaction of sodium sulfate waste salt and ammonium dihydrogen phosphate in this invention can promote the decomposition of organic matter.

[0087] 4. Calcium ion removal rate

[0088] Industrial wastewater containing sodium sulfate was collected, and the calcium ion content in the wastewater was determined by EDTA titration, denoted as X1. The industrial wastewater containing sodium sulfate was treated with adsorption resin according to the methods of Examples 1-6 and Comparative Examples 1-3, respectively, to obtain sodium sulfate waste salt. The residual calcium ion content in the sodium sulfate waste salt was determined by EDTA titration, denoted as X2. The calcium ion removal rate (%) was calculated as (X1-X2) / X2×100%, and the results of the calcium ion removal efficiency determination are shown in Table 1.

[0089] Table 1 Calcium ion removal rate

[0090]

[0091] As shown in Table 1, the calcium ion removal rate of Examples 3-4 of the present invention is higher than that of Examples 1-2. This is because Examples 3-4 use 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and 2,3,5,6-tetrafluorophenol to prepare modified polystyrene resin, and then treat industrial wastewater containing sodium sulfate with the modified polystyrene resin, while Examples 1-2 use chloromethyl polystyrene resin. The calcium ion removal rate of Examples 3-4 of the present invention is higher than that of Comparative Examples 1-2 because Comparative Example 1 uses only 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline to prepare modified polystyrene resin, and Comparative Example 2 uses only 2,3,5,6-tetrafluorophenol to prepare modified polystyrene resin. The calcium ion removal rate of Example 3 of the present invention is higher than that of Example 4 because of the different amounts of modified polystyrene resin used. This indicates that the synergistic use of 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and 2,3,5,6-tetrafluorophenol to prepare modified polystyrene resin can improve the removal rate of calcium ions from industrial wastewater containing sodium sulfate.

[0092] The calcium ion removal rates of Examples 5-6 of this invention are higher than those of Example 3 because Examples 5-6 further used 1,4-diisocyanate butane to prepare modified polystyrene resin. The calcium ion removal rates of Examples 5-6 are higher than those of Comparative Example 3 because Comparative Example 3 only used 1,4-diisocyanate butane to prepare modified polystyrene resin, without using 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and 2,3,5,6-tetrafluorophenol. The calcium ion removal rate of Example 5 of this invention is higher than that of Example 6 because of the different amounts of modified polystyrene resin used. This indicates that further using 1,4-diisocyanate butane to prepare modified polystyrene resin can further improve the removal rate of calcium ions from industrial wastewater containing sodium sulfate.

[0093] 4. Sodium hexametaphosphate yield

[0094] Following the methods of Examples 1-6 and Comparative Examples 1-3, industrial wastewater containing sodium sulfate was converted into sodium hexametaphosphate. According to the industry standard for industrial sodium hexametaphosphate HG / T 2519—2017, the yield of sodium hexametaphosphate obtained in Examples 1-6 and Comparative Examples 1-3 was analyzed, and the yield of sodium hexametaphosphate was calculated. The yield (%) = actual yield of sodium hexametaphosphate / theoretical yield of sodium hexametaphosphate × 100%. The measurement results are shown in Table 2.

[0095] Table 2. Yield of sodium hexametaphosphate (%)

[0096]

[0097] As shown in Table 2, the sodium hexametaphosphate yield in Examples 3-4 of this invention is higher than that in Examples 1-2. This is because Examples 3-4 used 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and 2,3,5,6-tetrafluorophenol to prepare modified polystyrene resin, and used the modified polystyrene resin to adsorb and remove calcium ion impurities from industrial wastewater containing sodium sulfate, initially obtaining sodium sulfate waste salt. The sodium sulfate waste salt was then reacted with a phosphorus source to convert it into sodium hexametaphosphate, thereby increasing the yield of sodium hexametaphosphate. In contrast, Examples 1-2 used chloromethyl polystyrene resin. The sodium hexametaphosphate yield in Examples 3-4 of this invention is higher than that in Comparative Examples 1-2 because Comparative Example 1 only used 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline to prepare modified polystyrene resin, and Comparative Example 2 only used 2,3,5,6-tetrafluorophenol to prepare modified polystyrene resin. The sodium hexametaphosphate yield in Example 3 of this invention is higher than that in Example 4 because of the different amounts of modified polystyrene resin used. This indicates that the synergistic use of 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and 2,3,5,6-tetrafluorophenol to prepare modified polystyrene resin, and the use of the modified polystyrene resin to remove calcium ion impurities from industrial wastewater containing sodium sulfate, initially obtaining sodium sulfate waste salt, and then reacting the sodium sulfate waste salt with a phosphorus source to convert it into sodium hexametaphosphate, can effectively improve the yield of sodium hexametaphosphate.

[0098] The sodium hexametaphosphate yield in Examples 5-6 of this invention is higher than that in Example 3 because Examples 5-6 further use 1,4-diisocyanate butane to prepare modified polystyrene resin. The sodium hexametaphosphate yield in Examples 5-6 is higher than that in Comparative Example 3 because Comparative Example 3 only uses 1,4-diisocyanate butane to prepare modified polystyrene resin, without using 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and 2,3,5,6-tetrafluorophenol. The sodium hexametaphosphate yield in Example 5 of this invention is higher than that in Example 6 because of the different amounts of modified polystyrene resin used. This indicates that further using 1,4-diisocyanate butane to prepare modified polystyrene resin, and using the modified polystyrene resin to remove calcium ion impurities from industrial wastewater containing sodium sulfate to initially obtain sodium sulfate waste salt, and then reacting the sodium sulfate waste salt with a phosphorus source to convert it into sodium hexametaphosphate, can further improve the sodium hexametaphosphate yield.

[0099] The conventional operations in the operation steps of this invention are well known to those skilled in the art and will not be described in detail here.

[0100] The embodiments described above provide a detailed explanation of the technical solution of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion, comprising: firstly, stirring industrial wastewater containing sodium sulfate with an adsorption resin, filtering, and rotary evaporating to obtain sodium sulfate waste salt; then reacting the sodium sulfate waste salt with a phosphorus source at high temperature, followed by rapid cooling and crystallization to obtain sodium hexametaphosphate, while simultaneously recovering the organic waste gas generated in the reaction and converting it into a valuable substance; wherein the phosphorus source includes at least ammonium dihydrogen phosphate and / or phosphoric acid, the organic waste gas includes at least one of sulfur trioxide gas and ammonia gas, and the valuable substance includes ammonium sulfate or sulfuric acid; The ratio of sodium sulfate-containing industrial wastewater to adsorption resin is 1 mL: 0.005-0.01 g; the mass ratio of sodium sulfate waste salt to phosphorus source is 1:1-2; in the high-temperature reaction, the reaction temperature is 500-800℃. The adsorbent resin is a modified polystyrene resin; the modified polystyrene resin has carbonyl groups and phenolic groups; in the preparation of the modified polystyrene resin, chloromethyl polystyrene resin is first swollen in 1,2-dichloroethane, and then reacted with 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline and 2,3,5,6-tetrafluorophenol to obtain the modified polystyrene resin.

2. The method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion as described in claim 1, characterized in that, In the high-temperature reaction, the heating rate is 6-16℃ / min.

3. The method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion as described in claim 1, characterized in that, In the high-temperature reaction, the reaction time is 0.4-2 hours.

4. The method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion as described in claim 1, characterized in that, In the rapid cooling crystallization, the cooling rate is 4-100℃ / min.

5. The method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion as described in claim 1, characterized in that, The ratio of chloromethyl polystyrene resin to 1,2-dichloroethane is 1g:10-20mL.

6. The method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion as described in claim 1, characterized in that, The mass ratio of the chloromethyl polystyrene resin to 2-methyl-3-(1-pyrrolidinylcarbonyl)aniline is 1:0.02-0.

1.

7. The method for removing organic matter from industrial waste salt and simultaneously achieving high-value conversion as described in claim 1, characterized in that, The mass ratio of the chloromethyl polystyrene resin to 2,3,5,6-tetrafluorophenol is 1:1-2.

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