Method for Preparing Cuprous Chloride by High-value Utilization of Chloride Ion-containing Wasterwater

Abstract

The disclosure discloses a method for preparing cuprous chloride by high-value utilization of chloride ion-containing wastewater, belonging to the field of wastewater treatment. According to the disclosure, wastewater containing chloride ions is taken, and the pH is maintained at 2 to 3.5. Cuprous oxide is added by 50 to 80% of a theoretical amount of the cuprous oxide according to a Cl.sup.− concentration for reaction 8 to 15 min. Centrifugation is performed to obtain crude cuprous chloride and supernatant. Cuprous oxide is added to the resulting supernatant for reaction 8 to 15 min, and a total of cuprous oxide added in two reactions accounts for 90 to 100% of the theoretical amount. Centrifugation is performed after the reaction to obtain crude cuprous chloride. According to the method of the disclosure, the amount of cuprous oxide used is greatly reduced, and the purity of the cuprous chloride is improved.

Claims

1. A method for preparing cuprous chloride by high-value utilization of chloride ion-containing wastewater, wherein the method comprises the following steps: (1) primary reaction: taking wastewater containing chloride ions and adjusting the pH to 2 to 3.5; then, adding 50% to 80% of a theoretical amount of cuprous oxide according to a Cl.sup.− concentration, and maintaining the pH at 2 to 3.5 during this period; reacting with stirring for 8 to 15 minutes after the addition of the cuprous oxide; and performing centrifugation after the reaction to obtain crude cuprous chloride and supernatant, the supernatant is to be subjected to a secondary reaction; (2) secondary reaction: adding cuprous oxide to the supernatant obtained in step (1), with a total of cuprous oxide added in both the primary reaction and the secondary reaction accounting for 90% to 100% of the theoretical amount, and maintaining the pH between 2 and 3.5 during this period; reacting with stirring for 8 to 12 minutes after the addition of the cuprous oxide; and performing centrifugation after the reaction to obtain crude cuprous chloride; and (3) performing acid washing, ethanol washing and drying on the crude cuprous chloride obtained in step (1) and step (2).

2. The method for preparing cuprous chloride by high-value utilization of chloride ion-containing wastewater according to claim 1, wherein the concentration of chloride ions in the wastewater containing chloride ions is 10 to 100 g/L.

3. The method for preparing cuprous chloride by high-value utilization of chloride ion-containing wastewater according to claim 1, wherein the adjusting the pH to 2 to 3.5 is implemented by adding sulfuric acid, and the sulfuric acid is continuously added to maintain the pH of a system constant between 2 and 3.5.

4. The method for preparing cuprous chloride by high-value utilization of chloride ion-containing wastewater according to claim 1, wherein temperature of the reactions in step (1) and step (2) is 10 to 40° C.

5. The method for preparing cuprous chloride by high-value utilization of chloride ion-containing wastewater according to claim 1, wherein the cuprous oxide is added in portions in processes of the primary reaction and the secondary reaction.

6. The method for preparing cuprous chloride by high-value utilization of chloride ion-containing wastewater according to claim 5, wherein portion-wise addition comprises addition in 3 to 5 portions, with an interval of 0.5 to 1 minutes each time.

7. The method for preparing cuprous chloride by high-value utilization of chloride ion-containing wastewater according to claim 1, wherein in step (1), the reaction occurs in an oxygen-free environment in the process of the primary reaction or the secondary reaction.

8. The method for preparing cuprous chloride by high-value utilization of chloride ion-containing wastewater according to claim 1, wherein in step (3), the acid washing comprises: adding a certain volume of sulfuric acid solution with pH value between 2 to 3 to wash the crude cuprous chloride, performing centrifugation, and repeating the operations 1 to 3 times to obtain acid-washed cuprous chloride; the ethanol washing comprises: adding a certain volume of anhydrous ethanol to further wash the resulting acid-washed cuprous chloride, performing centrifugation, and repeating the operations 1 to 2 times to obtain ethanol-washed cuprous chloride.

9. A fly ash treatment method, wherein the method comprises washing fly ash with water to obtain a fly ash water washing solution, and then performing treatment by using the method for preparing cuprous chloride by high-value utilization of chloride ion-containing wastewater according to claim 1.

10. A method of garbage treatment, wherein garbage is firstly incinerated, then fly ash obtained after garbage incineration is washed with water to obtain a fly ash water washing solution, and then, treatment is performed by using the method for preparing cuprous chloride by high-value utilization of chloride ion-containing wastewater according to claim 1.

Description

BRIEF DESCRIPTION OF FIGURES

[0036] FIG. 1 is a flowchart of removing chlorine with cuprous oxide according to the disclosure.

DETAILED DESCRIPTION

[0037] Determination of chloride ions and calculation formula for chlorine removal rate: LEI-Cl PXSJ-216F ion meter

[00001]$\begin{array}{cc}{\omega }_{1=}\frac{c1v1-c2v2}{c1v1}\times 100\%.& \mathrm{Formula}\left(1\right)\end{array}$

[0038] In Formula (1), c1 and v1 represent the Cl.sup.− concentration and volume of an initial solution, while c2 and v2 represent the Cl.sup.− concentration and volume of a chlorine-removed solution.

[0039] Determination method of purity of cuprous chloride: performing determination according to a method in the GB/T 27562-2011 “Industrial Cuprous Chloride” standard, while performing verification with ICP; and performing characterization of cuprous chloride by XRD.

[0040] Calculation formula of yield of cuprous chloride:

[00002]$\begin{array}{cc}\frac{m2}{m1}\times 100\%.& \mathrm{Formula}\left(2\right)\end{array}$

[0041] In Formula (2), m2 represents the total mass of a product, and m1 represents the total mass of input cuprous oxide.

[0042] The disclosure will be further described in conjunction with examples, but the embodiments of the disclosure are not limited thereto.

[0043] The chlorine-containing wastewater is a fly ash water washing solution, which is from a garbage incineration plant company in Jiangsu, with the chloride ion concentration of 0.8 to 1.5 mol/L.

[0044] Preparation method of cuprous oxide: glucose reduction method: with intense stirring, 10 mL of glucose solution with the concentration of 50 g/L is added to 50 mL of copper acetate solution with the concentration of 10 g/L and stirring is performed for 10 min. Then, 25 mL of sodium hydroxide solution with the concentration of 20 g/L is added to the mixture at 70° C. and stirring is kept for 1 h. Centrifugation is performed to obtain a product, the product is rinsed 3 times with deionized water and anhydrous ethanol (centrifuge speed 11000 r/min), and vacuum drying is performed on the product at 60° C. to a constant weight.

[0045] Electrolysis method: a copper plate is used as an anode, a titanium mesh is used as a cathode, a salt solution is used as an anode electrolyte, CTAB (hexadecyl trimethyl ammonium bromide) is used as an additive, and a sodium hydroxide solution is used as a cathode. In a reaction process, the anode solution needs to be continuously stirred, and a surface current density during the reaction is controlled to be 30, 40 and 50 A/m.sup.2. After 1 h of reaction, an anodic precipitate is separated, rinsed, filtered, and dried to obtain a finished cuprous oxide product.

Example 1

[0046] (1) Primary reaction: preparation of crude cuprous chloride: 100 ml of fly ash water washing solution (Cl.sup.− concentration of 30 g/L) was taken. Air was introduced into a system for 4 h. In a case where it was detected that pH was around 7, sulfuric acid was dropwise added until pH was 2.5. After that, Cu.sub.2O was added in portions (added in three portions by 62.5%, 25% and 12.5% of the addition amount in sequence, with an interval of 1 min) by 50%, 60%, 70%, 80%, 90%, 100% and 120% (corresponding to NaCl:Cu.sub.2O=1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5 and 1:0.6, respectively) of a theoretical addition amount of cuprous chloride (6.05 g). During this period, the sulfuric acid was continuously added to maintain the pH at around 2.5. Stirring was performed at room temperature for 10 min. Centrifugation was performed after the reaction to obtain crude cuprous chloride and supernatant. The crude cuprous chloride was subjected to post-treatment. The supernatant was to be subjected to a secondary reaction.

[0047] (2) Secondary reaction: the supernatant obtained in step (1) was taken. Cu.sub.2O was added such that the total addition amount in step (1) and step (2) was 96% or 100% of the theoretical addition amount (added in three portions, the same as the primary reaction). The primary reaction was repeated with same steps. After the reaction, crude cuprous chloride was obtained, and was merged with the crude cuprous chloride obtained from the primary reaction.

[0048] (3) Product post-treatment: acid washing: 80 mL of sulfuric acid solution with pH=2.6 was added to wash the above-mentioned crude product, centrifugation was performed again, and the operations were repeated twice to obtain acid-washed cuprous chloride. Ethanol washing: 80 ml of anhydrous ethanol was added to further wash the above-mentioned cuprous chloride, centrifugation was performed, and the operations were repeated twice to obtain ethanol-washed cuprous chloride. Drying: the above-mentioned cuprous chloride was placed in a vacuum drying oven and dried at 45° C. for 60 min to obtain a cuprous chloride product. Supernatant of residual chlorine can be reused for washing fly ash.

[0049] The results of the primary reaction in this example are shown in Table 1. Comprehensively considering influencing factors of product purity and yield, when NaCl:Cu.sub.2O≥1:0.5, although there was a certain improvement in chlorine removal effect, the purity of the product cuprous chloride significantly decreased. Therefore, it was preferable that addition was performed by NaCl:Cu.sub.2O=1:0.25 to 0.45, i.e., by 50 to 90% of the theoretical amount of Cu.sub.2O in the primary reaction, and remaining chloride ions were left for the secondary reaction.

TABLE-US-00001 TABLE 1 Influence of Molar Ratio of Primary Reaction on Chlorine Removal Effect and Cuprous Chloride NaCl:Cu.sub.2O 1:0.25 1:0.3 1:0.35 1:0.4 1:0.45 1:0.5 1:0.6 Chlorine removal rate (%) 48.39 58.18 68.13 76.24 84.75 88.87 89.66 Product purity (%) 98.15 98.04 98.18 98.14 95.03 85.46 78.38 Product yield (%) 83.13 83.63 85.9 87.8 86.39 88.52 90.63

[0050] Reaction conditions: initial Cl.sup.− (30 g/L), pH value=2.5, room temperature, 10 min, and stirring speed 400 r/min.

[0051] The chlorine removal effect obtained from the secondary reaction is shown in Table 2. Compared with Table 1, it can be seen that in a case of the same addition amount as the first time of addition (or even less, the addition amount was 100% or 120% in one reaction, while the total added amount in two reactions was 96%), the cuprous oxide was added in two times to obtain a better chlorine removal effect and higher product concentration. Taking 80%+20% as an example, the purity of the final resulting product cuprous chloride could reach 97% or above and the chlorine removal rate could also reach as high as 95.8%, which was significantly higher than an effect of adding the cuprous oxide by 100% once (the purity of the cuprous chloride was 85.46%, and the chlorine removal rate was 88.87%). Therefore, the method of adding the cuprous oxide in the two reactions was selected to treat water-washed fly ash water. Furthermore, it can be seen from Table 2 that when the addition amount in the primary reaction was 50% to 80% (the addition amount in the corresponding secondary reaction was 50% to 20%), it can be obtained that the chlorine removal effect was 95% or above and the purity of the cuprous chloride product was 97% or above. Taking 80%+20% as an example, when the cuprous oxide was added in an appropriate small amount (16%) for the second time, although the chlorine removal rate would be slightly reduced, the product purity could be slightly improved. Therefore, in order to reduce costs, a 80%+16% dosing manner was preferred.

TABLE-US-00002 TABLE 2 Influence of Molar Ratio of Secondary Reaction on Chlorine Removal Effect and Cuprous Chloride NaCl:Cu.sub.2O 1:0.25 1:0.2 1:0.15 1:0.1 1:0.08 1:0.05 Corresponding primary reaction 1:0.25 1:0.3 1:0.35 1:0.4 1:0.4 1:0.45 Chlorine removal rate (%) 48.63 38.91 29.36 19.56 18.86 9.85 Product purity (%) 96.05 96.39 96.14 96.26 96.61 92.14 Product yield (%) 91.25 91.42 90.89 90.52 89.53 89.21

[0052] Reaction conditions: initial Cl.sup.− (30 g/L), pH value=2.5, room temperature, 10 min, and stirring speed 400 r/min.

Example 2

[0053] Taking Example 1 of adding by 80% in the primary reaction and adding by 16% in the secondary reaction as an example, the time of a reaction with stirring was changed to 2, 5, 8, 10 (Example 1), 12 and 15 min. Other operating steps were the same as those in Example 1. The results are shown in Table 3. It can be seen that when the reaction stirring time was 10 to 15 min, not only could the chlorine removal rate be ensured, but also it could be ensured that the purity of the cuprous chloride was not less than 96%. An optimal reaction effect was achieved at about 10 min. After that, a further reaction might lead to release of chloride ions and oxidation and dismutation of cuprous ions, such that the product purity was slightly reduced. It was most preferred that the time was controlled at 10 to 12 min.

TABLE-US-00003 TABLE 3 Influence of Reaction Stirring Time on Overall Chlorine Removal Effect and Cuprous Chloride T/min 2 5 8 10 12 15 Chlorine removal rate (%) 62.19 82.74 90.64 95.10 95.10 92.47 Product purity (%) 67.42 84.95 93.10 97.89 97.55 96.54 Product yield (%) 94.92 92.43 89.34 88.1 87.5 87.7

[0054] Reaction conditions: initial Cl.sup.− (30 g/L), pH value=2.5, room temperature, stirring speed 400 r/min, and adding by 80%+16%.

Example 3

[0055] Taking Example 1 of adding by 80% in the primary reaction and adding by 16% in the secondary reaction as an example, the reaction stirring speed in Example 1 was changed to 200 r/min and 600 r/min. Other operating parameters were consistent with those in Example 1. The results are shown in Table 4. It can be seen that the stirring speed had little influence on the product.

TABLE-US-00004 TABLE 4 Influence of Stirring speed on Overall Portion-wise Chlorine Removal Effect and Cuprous Chloride r/min 200 400 600 Chlorine removal rate (%) 95.02 95.10 95.05 Product purity (%) 97.73 97.89 97.84 Product yield (%) 88.6 88.1 88.3

[0056] Reaction conditions: initial Cl.sup.− (30 g/L), pH value=2.5, room temperature, and reacting with stirring for 10 min.

Example 4

[0057] Taking Example 1 of adding by 80% in the primary reaction and adding by 16% in the secondary reaction as an example, the initial concentration of chloride ions in Example 1 was changed to 10, 40, 50 and 100 g/L, respectively. Other operating parameters were consistent with those in Example 1. The results are shown in Table 5.

[0058] It can be seen that the initial concentration of chloride ions shall not be too high. To ensure the product purity, the initial concentration shall be controlled to be 100 g/L or below, preferably not exceeding 50 g/L, and more preferably 30 g/L or below.

TABLE-US-00005 TABLE 5 Influence of Cl.sup.− Concentration on Overall Chlorine Removal Effect and Cuprous Chloride g/L 10 30 40 50 100 Chlorine removal rate (%) 96.23 95.10 94.58 93.71 90.53 Product purity (%) 97.93 97.89 97.59 95.87 93.68 Product yield (%) 88.2 88.1 89.2 89.7 91.4

[0059] Reaction conditions: pH value=2.5, room temperature, 10 min, and stirring speed 400 r/min.

Example 5

[0060] (1) Primary reaction: preparation of crude cuprous chloride: 100 ml of fly ash water washing solution (Cl.sup.− concentration of 30 g/L) was taken. Air was introduced into a system for 4 h. In a case where it was detected that pH was around 7, sulfuric acid was dropwise added until pH was 2.5. After that, Cu.sub.2O (added at once) was added by 80% of the theoretical addition amount of cuprous oxide (6.05 g). During the period, the sulfuric acid was continuously added to maintain the pH at around 2.5. Stirring was performed at room temperature for 10 min. Centrifugation was performed after the reaction to obtain crude cuprous chloride and supernatant. The crude cuprous chloride was subjected to post-treatment. The supernatant was to be subjected to the secondary reaction.

[0061] (2) Secondary reaction: the supernatant obtained in step (1) was taken. Cu.sub.2O was added such that the total addition amount in step (1) and step (2) was 96% of the theoretical addition amount (added at once). The primary reaction was repeated with same steps. After the reaction, crude cuprous chloride was obtained, and was merged with a primary reaction product. The Cl.sup.− concentration decreased to 2.97 g/L after the supernatant reacted, and the chlorine removal effect reached 90.1%.

[0062] (3) Product post-treatment: acid washing: 80 ml of sulfuric acid solution with pH=2.6 was added to wash the above-mentioned crude product, centrifugation was performed again, and the operations were repeated twice to obtain acid-washed cuprous chloride. Ethanol washing: a certain volume of anhydrous ethanol was added to further wash the above-mentioned cuprous chloride, centrifugation was performed, and the operations were repeated twice to obtain ethanol-washed cuprous chloride. Drying: the above-mentioned cuprous chloride was placed in a vacuum drying oven and dried at 45° C. for 60 min to obtain 5.15 g of cuprous chloride product, with a yield of 85.2%, and the product purity was determined to be 95.16%. A reaction solution was merged for water washing of fly ash.

Example 6

[0063] Taking Example 1 of adding by 80% in the primary reaction and adding by 16% in the secondary reaction as an example, a stirring reaction process was performed in an oxygen-free environment (protected by introducing nitrogen gas). Other operating steps and parameters were the same as those in Example. The results showed that after the supernatant reacted, the concentration of Cl.sup.− decreased to 1.41 g/L, and the chlorine removal effect reached 95.3%. 5.40 g of cuprous chloride product was obtained, with a yield of 89.4%, and the product purity was determined to be 98.56%. It can be seen that the oxygen-free environment can slightly improve the treatment effect, but the improvement is not significant.

Example 7

[0064] Preparation of crude cuprous chloride: 100 ml of fly ash water washing solution (Cl.sup.− concentration of 30 g/L) was taken. Air was introduced into a system for 4 h. In a case where it was detected that pH was around 7, sulfuric acid was dropwise added until pH was 0.5, 1, 1.5 and 2. After that, Cu.sub.2O was added in portions (added in three portions by 62.5%, 25% and 12.5% of the addition amount in sequence, with an interval of 1 min) by theoretical NaCl:Cu.sub.2O=1:0.5. During this period, the sulfuric acid was continuously added to maintain the pH or the sulfuric acid was added at once (the total amount of the sulfuric acid was consistent). Stirring was performed at room temperature for 10 min. Centrifugation was performed after the reaction to obtain crude cuprous chloride and supernatant. The crude cuprous chloride was subjected to post-treatment.

[0065] The results are shown in Table 6. It can be seen that in a case of the same amount of sulfuric acid, when the sulfuric acid was continuously added to maintain a stable state of the pH value of the system, a better chlorine removal effect and a higher-purity product can be obtained.

TABLE-US-00006 TABLE 6 Comparison Between Addition at Once and Continuous Addition of Sulfuric Acid pH value Sulfuric acid 0.5 1 1.5 2 addition At Continuous At Continuous At Continuous At Continuous manner once addition once addition once addition once addition Chlorine 83.52 86.73 82.04 85.36 82.26 85.29 76.42 78.94 removal rate (%) Product 73.95 80.52 79.31 85.25 78.25 85.46 71.28 77.53 purity (%) Product 86.63 84.31 87.41 85.51 88.42 85.37 89.63 93.73 yield (%)

[0066] Reaction conditions: initial Cl.sup.− (30 g/L), molar ratio (NaCl:Cu.sub.2O=1:0.5), room temperature, 10 min, and stirring speed 400 r/min. Note: Continuous adjustment refers to continuously add the amount of sulfuric acid, used for adjusting to 0.5 at once, in portions to keep the pH value of the system constant.

Example 8

[0067] Taking Example 1 of adding by 80% in the primary reaction and adding by 16% in the secondary reaction as an example, the pH was adjusted to 1, 1.5, 2, 2.5 (Example 1), 3 and 3.5. Other operating steps were the same as those in Example 1. The results are shown in Table 7. Comprehensively considering factors in two aspects of the chlorine removal effect and product purity, it was preferred that the pH of the system was continuously controlled to be 2 to 3.5, and most preferably 2 to 3.

TABLE-US-00007 TABLE 7 Influence of pH Value on Secondary Overall Reaction pH value 1 1.5 2 2.5 3 3.5 Chlorine 96.79 96.02 95.84 95.10 94.98 93.29 removal rate (%) Product purity 86.54 94.21 97.32 97.89 97.73 97.32 (%) Product yield 87.42 86.75 86.3 88.1 88.26 88.28 (%)

[0068] Reaction conditions: initial Cl.sup.− (30 g/L), room temperature, 10 min, stirring speed 400 r/min, adding by 80% in the primary reaction and adding by 16% in the secondary reaction.

Example 9

[0069] Taking Example 1 of adding by 80% in the primary reaction and adding by 16% in the secondary reaction as an example, the chlorine-containing wastewater in Example 1 was changed to a copper electrolyte for preparing cuprous oxide, with the chloride ion content of 49.7 g/L and no air was needed to be introduced. Other operating parameters were consistent with those in Example 1. The cuprous oxide was added in portions by 80%+16% of the theoretical addition amount of cuprous oxide (10.02 g). After the supernatant reacted, the Cl.sup.− concentration decreased to 2.2 g/L, and the chlorine removal effect reached 95.2%. 8.95 g of cuprous chloride product was obtained, with a yield of 89.3%, and the product purity was determined to be 98.63%. This indicates that this method is not only applicable to the fly ash water washing solution, but also applicable to the treatment of other chlorine-containing wastewater.

Example 10

[0070] Taking Example 1 of adding by 80% in the primary reaction and adding by 16% in the secondary reaction as an example, the cuprous oxide was added in portions (added in 3 to 5 times with an interval of 0.5 to 1 min; when added in 3 times, 10 to 70%, 10 to 70% and 10 to 70% of cuprous oxide were added in sequence; when added in 4 times, 10 to 60%, 10 to 60%, 10 to 60% and 10 to 60% of cuprous oxide were added in sequence; and when added in 5 times, 10 to 50%, 10 to 50%, 10 to 50%, 10 to 50% and 10 to 50% of cuprous oxide were added in sequence) in the processes of the primary reaction and the secondary reaction. Other operating parameters were the same as those in Example 1.

[0071] After testing, the chlorine removal rate reached 95% or above, the yield of the cuprous chloride was 88% or above, and the purity was 97% or above.

TABLE-US-00008 TABLE 8 Influence of Number of Times of Portion- wise Addition on Secondary Overall Reaction Number of times 3 4 5 Chlorine removal rate (%) 95.10 95.12 95.09 Product purity (%) 97.89 97.88 97.90 Product yield (%) 88.10 88.12 88.10

[0072] Reaction conditions: initial Cl.sup.− (30 g/L), room temperature, 10 min, stirring speed 400 r/min, adding by 80% in the primary reaction and adding by 16% in the secondary reaction. When added in three times, the cuprous chloride was respectively added by 62.5%, 25% and 12.5% of the required addition amount, with an interval of 1 min. When added in four times, the cuprous chloride was respectively added by 50%, 25%, 12.5% and 12.5% of the required addition amount, with an interval of 1 min. When added in five times, the cuprous chloride was added respectively by 30%, 30%, 20%, 10% and 10% of the required addition amount, with an interval of 0.5 min.

[0073] Although the disclosure has been disclosed with preferred examples, it is not intended to limit the disclosure. Anyone familiar with this technology can make various modifications and modifications, without departing from the spirit and scope of the disclosure. Therefore, the scope of protection of the disclosure should be based on the scope defined in claims.