Method for High-Value Application of PTA Residue High-Concentration Bromine-Containing Wastewater to Preparation of Cuprous Bromide

Abstract

The disclosure discloses a method for high-value application of PTA residue high-concentration bromine-containing wastewater to preparation of cuprous bromide, belongs to the field of PTA residue treatment, and includes: firstly adjusting a pH value of the bromine-containing wastewater to 0.5-2, adding cuprous oxide in batches, taking a reaction for 3-20 min after the cuprous oxide is totally added to produce cuprous bromide, Solid liquid separation to obtain cuprous bromide, concentrating a liquid phase to recover inorganic salt while rest wastewater may be used as process water for application. By cuprous oxide addition and method regulation and control, a bromine removal rate is as high as 95% or higher, the cuprous bromide reaches yield of 90% or higher and purity of 95%. Meanwhile, sodium sulfate with the purity of 90% or higher may be obtained. High-value application of the PTA residue high-concentration bromine-containing wastewater is really realized.

Claims

1. A method for high-value application of bromine-containing wastewater to preparation of cuprous bromide, comprising: firstly adjusting a pH value of the bromine-containing wastewater to 0.5-2, adding cuprous oxide in batches, taking a reaction for 3-20 minutes after the cuprous oxide is totally added to produce cuprous bromide, performing solid-liquid separation to obtain solid and liquid phase ingredients, performing acid pickling, alcohol washing and drying on the solid to obtain the cuprous bromide, wherein the adding the cuprous oxide in batches refers to addition in 2-5 times at an interval of 0.5-1 minutes between every two times.

2. The method for high-value application of bromine-containing wastewater to preparation of cuprous bromide according to claim 1, wherein the liquid phase ingredients obtained through solid-liquid separation is subjected to concentration treatment to recover inorganic salt, and rest of wastewater is used as process water for application.

3. The method for high-value application of bromine-containing wastewater to preparation of cuprous bromide according to claim 1, wherein a bromine content in the bromine-containing wastewater is 10-200 g/L.

4. The method for high-value application of bromine-containing wastewater to preparation of cuprous bromide according to claim 3, the bromine-containing wastewater comprises PTA residue wastewater, and the PTA residue wastewater contains 60 wt% to 65 wt% of NaBr.

5. The method for high-value application of bromine-containing wastewater to preparation of cuprous bromide according to claim 1, wherein a pH value of the bromine-containing wastewater is adjusted to 0.5-2 by sulfuric acid.

6. The method for high-value application of bromine-containing wastewater to preparation of cuprous bromide according to claim 1, wherein the adding the cuprous oxide in batches refers to addition in 3-5 times.

7. The method for high-value application of bromine-containing wastewater to preparation of cuprous bromide according to claim 1, wherein an addition amount of the cuprous oxide is as follows through being metered in the content of bromide ions: mole ratio Br.sup.-:Cu.sub.2O=1:(0.45-0.55).

8. The method for high-value application of bromine-containing wastewater to preparation of cuprous bromide according to claim 1, wherein a reaction time after adding the cuprous oxide is 3-10 minutes.

9. The method for high-value application of bromine-containing wastewater to preparation of cuprous bromide according to claim 1, wherein the reaction is performed under stirring, and the stirring speed is 100-600 rpm.

Description

BRIEF DESCRIPTION OF FIGURES

[0035] FIG. 1 is a schematic diagram of a process flow process of the disclosure;

[0036] FIG. 2 is an XRD diagram of cuprous oxide, cuprous bromide and a cuprous bromide standard card; and

[0037] FIG. 3 is an XRD diagram of sodium sulfate and a sodium sulfate standard card.

DETAILED DESCRIPTION

[0038] A calculation formula of a bromine removal rate:

[00001]$\begin{array}{cc}{\text{ω}}_1=\left(1{\text{-C}}_2*{\text{V}}_2/{\text{C}}_1*{\text{V}}_1\right)*100& \text{­­­Formula (1).}\end{array}$

[0039] In Formula (1), C.sub.1 and C.sub.2 respectively represent bromine ion concentrations before and after reaction, and V.sub.1 and V.sub.2 respectively represent solution volumes before and after reaction.

[0040] Calculation formula of yield of cuprous bromide: [0041] Theoretically, 1 mol Cu.sub.2O may take a reaction with 2 mol Br.sup.-; [0042] When NaBr is excessive, through being calculated according to the added Cu.sub.2O:

[0043] In Formula (2), w.sub.1 is mass of added cuprous oxide, and w.sub.2 is mass of obtained cuprous bromide.

[0044] When Cu.sub.2O is excessive, being calculated according to Br.sup.-:

[00003]$\begin{array}{cc}{\text{ω}}_3={\text{w}}_3/\left({\text{C}}_3*{\text{V}}_3*143.45*0.5\right)*100& \text{­­­Formula (3).}\end{array}$

[0045] In Formula (3), C.sub.3 and V.sub.3 are respectively bromide ion concentration and solution volume before reaction, and w.sub.3 is mass of obtained cuprous bromide.

[0046] Determination or calculation method of purity of cuprous bromide:

[0047] determined by a method in a standard of GB/T 27562-2011 Chloride for “Industrial Use Cuprous”, and verified by ICP. The cuprous bromide is expressed through XRD.

[0048] PTA residue wastewater was from an environmental protection company in Jiangsu, wastewater mainly contained sodium bromide (60% to 65%), and the rest was sodium carbonate and sodium bicarbonate.

[0049] The disclosure will be further described in combination with examples, but the embodiment of the disclosure is not limited to these descriptions.

Example 1

[0050] Firstly, a sulfuric acid solution with a concentration of 2 mol/L was added for respectively adjusting pH values of PTA residue wastewater to 0.5, 1, 1.2, 1.5 and 2. At the same time, a proper amount of distilled water was added to adjust a bromide ion concentration to be 50 g/L. Cuprous oxide was added in batches (added in three times: 50 wt% for the first time, 30 wt% for the second time, and 20 wt% for the third time at an interval of 1 min between every two times), and a total addition amount of cuprous oxide was 1:0.5 through being metered by a mole ratio of NaBr to Cu.sub.2O. Under an oxygen-free condition (protection through nitrogen gas introduction), 2 mol/L of sulfuric acid solution was continuously added in a supplemented manner to maintain the pH stability. Reaction was taken for 5 min at a stirring speed of 400 r/min and a room temperature to produce cuprous bromide. Centrifugal separation was performed to obtain a cuprous bromide crude product, a certain volume of sulfuric acid solution with a pH value being 2 was added for acid pickling the solid-phase crude product, centrifugation was performed, and the operation was repeated once to obtain an acid pickled cuprous bromide. Then, a certain volume of absolute ethyl alcohol was added to continuously wash the obtained acid pickled cuprous bromide. Centrifugation was performed to obtain an alcohol washed cuprous bromide. The obtained alcohol washed cuprous bromide was put into a vacuum drying box to be dried for 60 min at 50° C. to obtain a cuprous oxide product. Then, liquid supernatant obtained through centrifugal separation was subjected to concentration drying treatment to recover inorganic salt of sodium sulfate, and rest wastewater might be used as process water for application.

[0051] The influence of a pH adjusting process of the PTA residue wastewater on the bromine removal effect was very obvious. The result was as shown in Table 1. Therefore, when the pH value is 0.5-1.5, the bromine removal rate may reach 90% or higher. Particularly, when the pH value is 0.5-1.2, the bromine removal rate may reach 95% or higher. When the pH value is 2 or higher, the bromine removal effect is poor, and the product yield and purity are very low.

TABLE-US-00001 Influence of pH value of PTA residue wastewater on bromine removal rate pH value 0.5 1 1.2 1.5 2 Bromine removal rate 95.6% 95.9% 96.3% 91.2% <60% CuBr yield 93.6% 93.4% 90.8% 92.1% <60% CuBr purity 90.1% 92.7% 95.6% 93.2% - Na.sub.2SO.sub.4 purity 88.7% 90.6% 91.5% 89.7% - Reaction condition: Br.sup.- (50 g/L), mole ratio (NaBr:Cu.sub.2O=1:0.5), room temperature, 5 min, and stirring speed: 400 r/min.

Example 2

[0052] Operation steps were the same as those in Example 1. At this moment, the pH value was selected to be 1.2, and the mole ratios of NaBr:Cu.sub.2O were respectively changed to be 1:0.45 and 1:0.55. The results were as shown in Table 2. Therefore, different addition amounts of cuprous oxide have certain influence on the bromine removal rate, but the influence is not great. However, when NaBr:Cu.sub.2O=1:0.55, the bromine removal rate and the product yield are both optimum.

TABLE-US-00002 Influence of mole ratio on bromine removal effect NaBr:Cu.sub.2O 1:0.45 1:0.5 1:0.55 Bromine removal rate 94.5% 96.3% 97.1% CuBr yield 83.9% 90.8% 92.6% CuBr purity 95.1% 95.6% 95.8% Na.sub.2SO.sub.4 purity 90.6% 91.5% 92.7% Reaction condition: Br.sup.-(50 g/L), pH value=1.2, room temperature, 5 min, and stirring speed: 400 r/min.

Example 3

[0053] Operation steps were the same as those in Example 1. At this moment, the pH value was selected to be 1.2, the mole ratio of NaBr:Cu.sub.2O was changed to be 1:0.55, and the reaction time was respectively 3, 10 and 20 min. The results were as shown in Table 3. Therefore, the bromine removal rate may be improved by prolonging the reaction time, but the effect improvement is very limited. Good bromine removal effect may be achieved within 3-20 min, but too short and too long time may both cause product purity reduction.

TABLE-US-00003 Influence of stirring time on bromine removal effect T/min 3 5 10 20 Bromine removal rate 95.1% 97.1% 97.5% 98.1% CuBr yield 91.4% 92.6% 92.8% 93.5% CuBr purity 93.2% 95.8% 95.3% 90.2% Na.sub.2SO.sub.4 purity 91.2% 92.7% 92.5% 89.5% Reaction condition: Br.sup.-(50 g/L), pH value=1.2, mole ratio NaBr:Cu.sub.2O=1:0.55, room temperature, and stirring speed: 400 r/min.

Example 4

[0054] Operation steps were the same as those in Example 1. At this moment, the pH value was selected to be 1.2, the mole ratio of NaBr:Cu.sub.2O was changed to be 1:0.55, and the stirring speeds were 200 and 600 r/min. The results were as shown in Table 4. Therefore, the influence of the stirring speed on the bromine removal rate is not great, and the bromine removal rate is optimum at a rotating speed of 400 r/min.

TABLE-US-00004 Influence of stirring speed on bromine removal effect r/min 200 400 600 Bromine removal rate 96.1% 97.2% 96.1% CuBr yield 91.3% 92.6% 92.5% CuBr purity 93.2% 95.8% 95.6% Na.sub.2SO.sub.4 purity 90.8% 92.7% 91.6% Reaction condition: Br.sup.-(50 g/L), pH value=1.2, mole ratio (NaBr:Cu.sub.2O=1:0.55), room temperature, and 5 min.

Example 5

[0055] Operation steps were the same as those in Example 1. At this moment, the pH value was selected to be 1.2, the mole ratio of NaBr:Cu.sub.2O was changed to be 1:0.55, and the concentrations of bromine ions were adjusted to be respectively 10, 30 and 100 g/L. The results were as shown in Table 5. Therefore, the removal rate of the method of the disclosure on low-concentration (lower than or equal to 50 g/L) bromine ions is as high as 97% or higher, and the bromine removal rate of the method of the disclosure on high-concentration (100 g/L) bromine ions can reach 93% or higher. Therefore, the method of the disclosure can be applicable to a bromine removal process of high-concentration PTA residue wastewater. However, when a bromine-ion concentration is higher than 100 g/L, the product purity is reduced.

TABLE-US-00005 Influence of Br.sup.- concentration on bromine removal effect g/L 10 30 50 100 Bromine removal rate >99% 98%~99% 97%~98% 93%~95% CuBr yield >95% 93%~94% 95%~96% >98% CuBr purity 95%~96% 95%~96% 95%~96% <90% Na.sub.2SO.sub.4 purity >90% 91%~92% 91%~92% <90% Reaction condition: pH value=1.2, mole ratio (NaBr:Cu.sub.2O=1:0.55), room temperature, 5 min, and stirring speed: 400 r/min.

Example 6

[0056] Firstly, a sulfuric acid solution with a concentration of 2-8 mol/L was added for respectively adjusting a pH value of PTA residue wastewater to 1-1.5. At the same time, a proper amount of distilled water was added to adjust a bromide ion concentration to be 30-50 g/L. Cuprous oxide was added in batches (added in 3-5 times at an interval of 0.5-1 min between every two times. When the cuprous oxide was added in 3 times, 10% to 70% of cuprous oxide, 10% to 70% of cuprous oxide, and 10% to 70% of cuprous oxide were sequentially added. When the cuprous oxide was added in 4 times, 10% to 60% of cuprous oxide, 10% to 60% of cuprous oxide, 10% to 60% of cuprous oxide, and 10% to 60% of cuprous oxide were sequentially added. When the cuprous oxide was added in 5 times, 10% to 50% of cuprous oxide, 10% to 50% of cuprous oxide, 10% to 50% of cuprous oxide, 10% to 50% of cuprous oxide, 10% to 50% of cuprous oxide were sequentially added.). A total addition amount of cuprous oxide was 1:0.55 through being metered by a mole ratio of NaBr to Cu.sub.2O. Under an oxygen-free condition (protection through nitrogen gas introduction), 2-8 mol/L of sulfuric acid solution was continuously added in a supplemented manner to maintain the pH stability. Reaction was taken for 5 min at a stirring speed of 400 r/min and a room temperature to produce cuprous bromide. Centrifugal separation was performed to obtain a cuprous bromide crude product, a certain volume of sulfuric acid solution with a pH value being 2-5 was added for acid pickling the solid-phase crude product, centrifugation was performed, and the operation was repeated for 1-3 times to obtain an acid pickled cuprous bromide. Then, a certain volume of absolute ethyl alcohol was added to continuously wash the obtained acid pickled cuprous bromide. Centrifugation was performed to obtain an alcohol washed cuprous bromide. The obtained alcohol washed cuprous bromide was put into a vacuum drying box to be dried for 30-120 min at 30-60° C. to obtain a cuprous oxide product. Then, liquid supernatant obtained through centrifugal separation is subjected to concentration drying treatment to recover inorganic salt of sodium sulfate, and rest wastewater may be used as process water for application

[0057] Through detection, the bromine removal rate was 97% or higher, the cuprous bromide had the yield of 90% or higher, and the purity of 95% or higher, and the sodium sulfate had the purity of 90% or higher.

Comparative Example 1

[0058] Operation was performed according to a method of Example 2 (mole ratio of NaBr:Cu.sub.2O was selected to be 1:0.55), however, the addition of cuprous oxide in batches was changed into once addition. Through the results, it was discovered that the bromine removal rate is basically unchanged, and may still reach 96% or higher. However, at this moment, the product purity may be reduced, the cuprous bromide product may cover parts of unreacted cuprous oxide, the purity is lower than 90%, and the purity of sodium sulfate may also be lower than 85%.

Comparative Example 2

[0059] The operation was performed according to Example 2 (mole ratio of NaBr:Cu.sub.2O was selected to be 1:0.55), and the reaction time was prolonged to 30 min. Through results, it was discovered that the bromine removal rate is improved, and may reach 99% or higher. However, at this moment, the purity of the cuprous bromide product is reduced, and is 86%. The reaction time is mainly too long, and cuprous ions slowly take a disproportionation reaction to produce copper ions and elemental copper.

[0060] The operation was performed according to Example 2 (mole ratio of NaBr:Cu.sub.2O was selected to be 1:0.55), and the oxygen-free condition was changed into oxygen condition (without nitrogen gas introduction). Through results, it was discovered that the product purity is reduced, the purity of cuprous bromide is 90%, and parts of cuprous bromide products are oxidized.

[0061] Although exemplary examples of the disclosure have been disclosed, these examples are not intended to limit the disclosure. Those skilled in the art will appreciate that various modifications, additions and substitutions may be made without departing from the scope and spirit of the disclosure as defined in the claims.