Method for removing chloride ions from a solution

Abstract

The present application belongs to the field of wastewater treatment, and particularly relates to a method for removing chloride ions in a solution, which comprises using a mixed amine modified resin to adsorb a water solution containing chloride ions to be treated to obtain a chloride-removed solution; the mixed amine modified resin is a resin modified with quaternary ammonium groups and tertiary amino groups. The mixed amine modified resin is used as an adsorbent, which can effectively improve the adsorption capacity and selectivity of chloride ions.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of star rubber synthetic coagulation water treatment in petrochemical industry, and particularly to a method for removing chlorine from star rubber and other polymer synthetic coagulation water. BACKGROUND

[0002] When star rubber and other polymers are synthesized, SiCl4 is added as a coupling agent after polymerization. After the reaction is completed, the product is obtained through hot water coagulation, washing, drying, etc. The high-temperature coagulation water in the coagulation process is recycled, which causes the enrichment of chlorine ions. When the concentration reaches a certain level, it will corrode stainless steel equipment.

[0003] Currently, there is no related treatment technology research report on removing chlorine from this type of coagulation wastewater. Similar research and technology are mainly aimed at removing chlorine ions from industrial wastewater and acidic wastewater, including precipitation method, electrochemical method, ion exchange method and evaporation concentration method, etc. For this type of high-temperature coagulation water, the following conditions need to be met: (1) the temperature is above 95℃, (2) the chlorine ion needs to be reduced from about 200mg / L to below 20mg / L, (3) no impurity elements that affect the rubber product can be introduced, (4) low operating cost, high degree of automation, safety and environmental protection.

[0004] In the prior art, the precipitation method: Ag or Hg elements react with chlorine ions to precipitate, which needs to introduce new elements, change the original system, and the treatment cost is high. The electrochemical method: uses electric adsorption and electrodialysis to dilute the solution, the membrane is easy to be blocked by colloidal particles, the removal effect is limited, the enrichment multiple of chlorine is not high, and the subsequent concentrated water treatment amount is large. The ion exchange method: poor selectivity of chlorine, large amount of waste alkali produced by elution and regeneration liquid, difficult to handle. The evaporation concentration method: suitable for desalination of high-concentration wastewater.

[0005] And according to the requirements of the above high-temperature coagulation water, the required treatment process needs to have the following characteristics: high temperature resistance, no metal elements, SO4 2- Plasma, good selectivity of chlorine ions, high removal rate, large adsorption capacity, low reagent consumption, low cost, etc. SUMMARY

[0006] The first object of the present application is to provide a method for removing chlorine ions in a solution, which aims to provide an adsorption and removal method for chlorine ions.

[0007] A method for removing chlorine ions in a solution, which uses a mixed amine modified resin to adsorb the chlorine ion containing water solution to be treated, and obtains a chlorine removed solution.

[0008] The mixed amine modified resin is a resin modified with quaternary ammonium groups and tertiary amino groups.

[0009] In the present application, the resin modified by mixed amine groups containing quaternary ammonium groups and tertiary amine groups is used to adsorb chloride ions, which can effectively improve the adsorption capacity and selectivity of chloride ions.

[0010] In the present application, the modification of mixed amine groups containing quaternary ammonium groups and tertiary amine groups in the resin is the key to synergistically improving the adsorption capacity and selectivity of chloride ions.

[0011] As a preference, in the mixed amine modified resin, the ratio of quaternary amine groups to tertiary amine groups is between 3 and 5:1, and the total exchange capacity is greater than or equal to 1.2 eq / L. Further studies have found that further controlling the modification ratio of quaternary amine groups and tertiary amine groups helps to further synergistically improve the adsorption capacity and selectivity of chloride ions.

[0012] In the present application, the mixed amine modified resin is a mixed amine modified polystyrene crosslinked divinylbenzene copolymer.

[0013] In the present application, the solution to be treated can be any solution that requires chloride removal. Preferably, the aqueous solution to be treated also contains sulfate ions. After adsorption by the mixed amine modified resin, chloride ions are selectively adsorbed, and a chloride-removed solution containing sulfate ions is obtained.

[0014] In the present application, thanks to the mixed amine modified resin, it can selectively distinguish between chloride ions and sulfate ions, and effectively improve the separation selectivity of chloride ions and sulfate ions.

[0015] In the present application, the aqueous solution to be treated is a polymer synthesis coagulation water, which is wastewater containing chloride ions and sulfate ions, and is preferably a coagulation water synthesized by star rubber. Further preferably, the polymer synthesis coagulation water contains rubber float and microparticles, has a chlorine concentration of 50-300 mg / L, a pH of 6-10, a conductivity of 100-1500 us / cm, and a temperature of 70-100℃.

[0016] As a preference, the polymer synthesis coagulation water is pre-filtered and the temperature is controlled to be 40-60℃.

[0017] In the present application, the adsorption method is not particularly limited, for example, it can be static adsorption or dynamic adsorption. Considering the process implementation, a column adsorption method is preferably used, the mixed amine modified resin is used as packing to form an adsorption column, and then the aqueous solution to be treated is passed through the adsorption column, so as to collect the chloride-removed solution after adsorption.

[0018] As a preference, in the column adsorption stage, the feed rate of the aqueous solution to be treated is 5-60 BV / h.

[0019] In the present application, the chloride-removed solution can be recycled to the polymer synthesis process.

[0020] In the present application, a step of regenerating the mixed amine modified resin is also included: after the mixed amine modified resin is saturated with adsorption, a hydroxide solution of alkali metal is used for desorption regeneration, a chlorate salt of alkali metal desorption solution is obtained, and the regenerated mixed amine resin is recycled.

[0021] The hydroxide of alkali metal is at least one of sodium hydroxide and potassium hydroxide.

[0022] As a preferred, the desorption solution is concentrated to obtain a chlorate salt of alkali metal.

[0023] In a specific method for removing chloride ions in the solution of the present application, the solution to be treated is the condensate water of star rubber polymer synthesis, and the treatment steps include:

[0024] Step 1: The high-temperature condensate water of polymer synthesis such as star rubber is first filtered through a full-automatic self-cleaning scraper filter to remove rubber powder, and then filtered through a precision filter to remove suspended solids;

[0025] Step 2: The filtered synthesis condensate water is sequentially cooled through heat exchanger 1 and heat exchanger 2, the cold side of heat exchanger 1 is the adsorbed solution, and the cold side of heat exchanger 2 is cooling water; the cooling water returns to the cooling water circulation system;

[0026] Step 3: Then, the adsorption column filled with mixed amine modified resin is used for adsorption to remove chlorine to obtain the adsorbed solution; after passing through the cold side of heat exchanger 1 of step 2, it returns to the condensate water system in the star rubber synthesis process for reuse;

[0027] Step 4: After the mixed amine modified resin is saturated with adsorption, it is sequentially washed through elution 1 and elution 2 to regenerate; elution 1 is eluted with elution circulating liquid to regenerate, to obtain the eluted solution, which is processed in subsequent step 5; elution 2 is eluted with prepared elution liquid to regenerate, to obtain the elution circulating liquid, which returns to the elution 1 process for use; the regenerated adsorption resin is recycled;

[0028] Step 5: The eluted solution is first concentrated by membrane technology to obtain fresh water and concentrated water; the fresh water returns to the preparation of elution liquid; the concentrated water is processed in subsequent step 6;

[0029] Step 6: The concentrated water concentrated by membrane technology is further concentrated by evaporation; the steam obtained by evaporation is condensed to obtain a condensate, which returns to the preparation of elution liquid; the mother liquor obtained by evaporation is processed in subsequent step 7;

[0030] Step 7: The evaporation mother liquor is obtained by cooling crystallization and filtration to obtain sodium chloride crystal salt and filtrate; the filtrate returns to the preparation of elution liquid;

[0031] Step 8: The concentrated fresh water by membrane technology, the condensed liquid of evaporation and the filtrate of cooling crystallization filtration are prepared into eluent after adding alkali, and the eluent is used for eluting 2 in step 4.

[0032] Further improvement, in step 1, the filter screen precision of the scraper filter is 10-50um, and the precision of the precision filter is 0.5-1um.

[0033] Further improvement, in step 2, the heat exchanger 1 and the heat exchanger 2 are plate heat exchangers, the heat exchange area of the heat exchanger 1 is 2-5 times of that of the heat exchanger 2; the temperature of the high-temperature condensed water after two heat exchange and cooling is 40-60℃.

[0034] Further improvement, in step 3, the adsorption liquid speed is 5-60BV / h; the adsorption resin is mixed amine group polystyrene cross-linked divinylbenzene copolymer, the proportion of quaternary amine group and tertiary amine group is 3-5:1, and the total exchange capacity is greater than 1.2eq / L.

[0035] Further improvement, in step 4, the elution liquid speed is 3-10BV / h; the elution cycle liquid in the elution 1 process is 2-5BV, and the elution liquid in the elution 2 process is 2-5BV; the elution liquid is 2-5% sodium hydroxide solution or 2-5% potassium hydroxide solution.

[0036] Further improvement, in step 5, the membrane technology is one of reverse osmosis and electrodialysis.

[0037] Further improvement, in step 6, the concentrated evaporation end temperature is 120-150℃, the mother liquor density is 1.35-1.55g / mL, and the concentration of sodium hydroxide in the mother liquor is 30-50%.

[0038] Further improvement, in step 7, the cooling crystallization end temperature is 10-30℃.

[0039] Further improvement, the high-temperature condensed circulating water generated in the process of star rubber polymer synthesis is the high-temperature condensed circulating water generated in the process of star rubber polymer synthesis, containing rubber floating objects and microparticles, containing chlorine concentration of 50-300mg / L, pH of 6-10, conductivity of 100-1500us / cm, and temperature of 70-100℃.

[0040] Compared with the prior art, the advantages of the present application are:

[0041] (1) The quaternary ammonium-tertiary amine composite modified resin is innovatively used for adsorbing chlorine, which can improve the adsorption capacity of chlorine ions based on the synergy of quaternary ammonium-tertiary amine, and unexpectedly improve the adsorption selectivity of chlorine ions and sulfate ions.

[0042] The removal rate of chloride ion can reach 92.4%, and the chloride ion in the effluent can be stably lower than 20 mg / L. Meanwhile, no other components except for hydroxide are introduced into the original system.

[0043] (2) The eluted solution containing sodium chloride and sodium hydroxide is pre-concentrated, and then concentrated by using a mixed solution of sodium chloride and sodium hydroxide, so that the solubility of sodium chloride and sodium hydroxide at different temperatures and the common ion effect are utilized. In this way, the concentration of sodium hydroxide is increased, and the solubility of sodium chloride is decreased, so that sodium chloride is crystallized and precipitated. Not only the loss of liquid caustic in the eluted solution is avoided, but also the chlorine in the whole system is opened. The whole process is realized without three wastes, water is recycled, and chlorine is obtained in the form of sodium chloride product.

[0044] (3) After comprehensive treatment, the treatment cost is greatly reduced, and the treatment cost per ton of water is as low as 2 yuan / ton. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The process flow diagram of Example 2 is shown. DETAILED DESCRIPTION

[0046] Example 1

[0047] The high-temperature circulating water of a rubber factory in a petrochemical industry has a solution pH of 9.1, and the average contents of chloride and sulfate ions are 151 mg / L and 83 mg / L, respectively.

[0048] 1 g of each of the chlorine adsorption resin, the quaternary amine group resin, the tertiary amine group resin, and the secondary amine group resin is added into 100 mL of raw water, respectively. After 6 h of oscillation adsorption, the de-chlorinated solution is analyzed. The chlorine adsorption resin is a mixed amine group polystyrene cross-linked divinylbenzene copolymer, and the ratio of the quaternary amine group and the tertiary amine group is 4:1. The mixed amine group modified resin (also referred to as the chlorine adsorption resin) is a modified polymer grafted with quaternary amine groups and tertiary amine groups, which is prepared by first performing chloromethylation on polystyrene cross-linked divinylbenzene beads in the presence of a catalyst, and then performing amination on the chloromethylated product in the presence of a catalyst and a certain proportion of quaternary amine and tertiary amine. The quaternary amine group resin, the tertiary amine group resin, and the secondary amine group resin are modified in the same way as the chlorine adsorption resin, and the only difference is that the quaternary amine group resin is modified only with quaternary amine groups, and the modification content is the same as the total amount of mixed amine of the chlorine adsorption resin. The tertiary amine group resin is modified only with tertiary amine groups, and the modification content is the same as the total amount of mixed amine of the chlorine adsorption resin.

[0049] The secondary amine group resin is modified only with secondary amine groups, and the modification content is the same as the total amount of mixed amine of the chlorine adsorption resin.

[0050] The obtained results are shown in the following table:

[0051]

[0052] The adsorption rate of the chlorine adsorption resin to chlorine is as high as 91.4%, and the adsorption effect of the other several to sulfate ions is higher.

[0053] Example 2:

[0054] In the condensation process of synthesis in a star rubber SBS production workshop of a petrochemical industry rubber factory, high-temperature condensation circulating water is generated. The water contains a large amount of white rubber floating particles, the temperature is 75-95°C, the solution pH is 9.1, the conductivity is about 638 us / cm, and the average chlorine content is about 158 mg / L.

[0055] The high-temperature condensation circulating water is pumped into a 50-um scraper self-cleaning filter and a 0.5-um PP filter core precision filter in sequence by a centrifugal pump for filtration to obtain a filtered liquid.

[0056] The filtered liquid is then sequentially heat-exchanged in a 2-m 2 316L plate heat exchanger and a 0.5-m 2 316L plate heat exchanger, with an inlet liquid velocity of 1 m 3 / h. After two-stage heat exchange, the outlet water temperature is 40-60°C.

[0057] Then, the heat-exchanged raw water is pumped into two adsorption columns filled with adsorption resin (the same as the chlorine adsorption resin in Example 1), each with a resin filling amount of 80-90 L, and the two columns are used in series, with an inlet liquid velocity of 1 m 3 / h, and the adsorption resin is a mixed polystyrene cross-linked divinylbenzene resin with a quaternary amine group and a tertiary amine group ratio of 4:1. While adsorbing, samples are taken at intervals for analysis of chlorine ion concentration, as shown in the following table:

[0058]

[0059] After chlorine removal by adsorption, the outlet water chlorine concentration is stable at <20 mg / L, and the average chlorine ion removal rate can reach 92.4%.

[0060] After adsorption saturation, a 3-5% liquid caustic solution is pumped into the column at a speed of 0.5 m 3 / h for elution. The obtained eluted liquid contains a chlorine ion concentration of 5.6 g / L and a TDS of 48 g / L.

[0061] The eluted liquid is pre-concentrated by electrodialysis to obtain about 50% concentrated water and 50% fresh water. The TDS of the concentrated water is 89 g / L.

[0062] 1 L of the concentrated water from the electrodialysis is heated and evaporated until the solution temperature reaches 145°C, at which point the evaporation is stopped, and 0.95 L of steam condensate water is collected.

[0063] After the evaporation, the solution was cooled to 20°C to crystallize sodium chloride, which was filtered off. The filtrate, containing 47% sodium hydroxide and 0.65% chloride ions, was used to prepare the eluent.

[0064] The above examples are only preferred embodiments of the present application, and the protection scope of the present application is not limited to the above examples. Any technical solutions falling within the concept of the present application shall fall within the protection scope of the present application. It should be pointed out that, for ordinary skilled persons in the art, improvements and refinements without departing from the principles of the present application shall also be considered as falling within the protection scope of the present application.

Claims

1. A method for removing chloride ions from a solution, characterized in that, A mixed amine-modified resin was used to adsorb chloride ions from the aqueous solution to be treated, and a dechlorinated solution was obtained. The mixed amine modified resin is a resin modified with quaternary ammonium groups and tertiary amine groups; In the mixed amine modified resin, the ratio of quaternary ammonium groups to tertiary ammonium groups is between 3 and 5:1, and the total exchange capacity is greater than or equal to 1.2 eq / L; The aqueous solution to be treated also contains sulfate ions. After adsorption by the mixed amine modified resin, chloride ions are selectively adsorbed to obtain a dechlorinated solution containing sulfate ions.

2. The method for removing chloride ions from a solution as described in claim 1, characterized in that, The mixed amine modified resin is a polystyrene crosslinked divinylbenzene copolymer modified with mixed amines.

3. The method for removing chloride ions from a solution as described in claim 1, characterized in that, The aqueous solution to be treated is polymer-synthesized condensed water.

4. The method for removing chloride ions from a solution as described in claim 3, characterized in that, The aqueous solution to be treated is condensed water synthesized from star-shaped rubber.

5. The method for removing chloride ions from a solution as described in claim 3, characterized in that, Polymer-synthesized coagulated water contains rubber-like floating matter and microparticles, with a chlorine concentration of 50-300 mg / L, a pH of 6-10, an electrical conductivity of 100-1500 μS / cm, and a temperature of 70-100℃.

6. The method for removing chloride ions from a solution as described in claim 3, characterized in that, The polymer synthesis condensate is pre-filtered and the temperature is controlled at 40-60℃.

7. The method for removing chloride ions from a solution as described in claim 1, characterized in that, The column adsorption method is used, in which the mixed amine modified resin is used as a packing material to form an adsorption column, and then the aqueous solution to be treated is flowed through the adsorption column to collect the dechlorinated liquid after adsorption.

8. The method for removing chloride ions from a solution as described in claim 7, characterized in that, During the column adsorption stage, the feed rate of the aqueous solution to be treated is 5-60 BV / h.

9. The method for removing chloride ions from a solution as described in claim 7, characterized in that, The dechlorinated liquid is recycled back into the polymer synthesis process.

10. The method for removing chloride ions from a solution according to any one of claims 1 to 9, characterized in that, After the mixed amine modified resin is saturated with adsorption, it is desorbed and regenerated using an alkali metal hydroxide solution to obtain an alkali metal chloride desorption solution, and the regenerated mixed amine resin is recycled.

11. The method for removing chloride ions from a solution as described in claim 10, characterized in that, The desorption solution was concentrated to obtain alkali metal chloride salts.

12. The method for removing chloride ions from a solution as described in claim 1, characterized in that, The solution to be treated is star-shaped rubber polymer synthetic condensate, and its treatment steps include: Step 1: The star-shaped rubber polymer synthesizes high-temperature condensed water, which first passes through a scraper filter to remove rubber particles; then it is filtered with a precision cartridge filter to remove suspended solids. Step 2: The filtered synthetic condensate water is cooled by heat exchanger 1 and heat exchanger 2 in sequence. The cold side of heat exchanger 1 is the adsorbed liquid, and the cold side of heat exchanger 2 is the cooling water; the cooling water is returned to the cooling water circulation system. Step 3: Then, the chlorine is removed by adsorption through an adsorption column containing mixed amine modified resin to obtain the adsorbed liquid; after passing through the cold side of heat exchanger 1 in step 2, it is returned to the condensate system in the star-shaped rubber synthesis process for reuse. Step 4: After the mixed amine modified resin is saturated with adsorption, it is eluted and regenerated through two processes, elution 1 and elution 2. In elution 1, the resin is eluted and regenerated with the elution circulating solution to obtain the eluted solution, which is then processed in the subsequent step 5. In elution 2, the resin is eluted and regenerated with the prepared elution solution to obtain the elution circulating solution, which is then returned to the elution 1 process for reuse. The regenerated adsorption resin is then recycled. Step 5: The eluent is first concentrated using membrane technology to obtain desalinated water and concentrated water; the desalinated water is returned to the eluent preparation; the concentrated water is then processed in the subsequent step 6. Step 6: The concentrated water obtained by membrane technology is further concentrated and evaporated; the vapor obtained by evaporation is condensed to obtain condensate, which is returned to the eluent for preparation; the mother liquor obtained by evaporation is processed in the subsequent step 7. Step 7: Evaporate the mother liquor, then cool and crystallize and filter to obtain sodium chloride crystals and filtrate; return the filtrate to the eluent for preparation. Step 8: The fresh water concentrated by membrane technology, the condensate from evaporation, and the filtrate from cooling crystallization filtration are mixed with alkali to prepare an eluent, which is used in the elution process 2 of step 4.

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