Method for recycling copper-containing wastewater from micro-etching

Abstract

A method for recycling a copper-containing wastewater from a micro-etching is provided, including: modifying a FeS material with a monomer including both carboxyl and sulfhydryl, a crosslinking agent, and a stabilizing and dispersing agent to obtain a FeS-based pH-responsive material CMC-FeS@HS #SiO.sub.2 #COOH, adding the FeS-based pH-responsive material to weakly-acidic copper-containing wastewater from the micro-etching to allow a reaction, and conducting processes such as sulfide precipitation, exchange, adsorption complexation, and flocculation precipitation to finally obtain a precipitate with CuS as a main component. This method makes full use of the pH responsiveness and abundant surface active sites of the FeS-based pH-responsive material, and can control a recovery rate of copper ions in the wastewater at 99.8% or more merely by adjusting a pH value of the copper-containing wastewater from the micro-etching.

Claims

1. A method for recycling a copper-containing wastewater from a micro-etching, comprising adding a FeS-based pH-responsive material to a weakly-acidic copper-containing wastewater from the micro-etching, to allow a reaction I to obtain a precipitate with CuS as a main component, wherein the FeS-based pH-responsive material is prepared through the following process: slowly adding a sulfide salt solution to a mixed solution comprising a modified crosslinking agent, a stabilizing and dispersing agent, and a ferrous salt, to allow a heterogeneous precipitation reaction to obtain the FeS-based pH-responsive material; wherein the modified crosslinking agent is obtained through a crosslinking reaction of a monomer comprising both carboxyl and sulfhydryl with a crosslinking agent; the reaction I is conducted at a pH value of 3.95 to 6.05 for 10 min to 25 min; a Cu.sup.2+/S.sup.2 molar ratio of the copper-containing wastewater from the micro-etching to the FeS-based pH-responsive material is 1:(1.0-1.25); the monomer comprising both the carboxyl and the sulfhydryl comprises at least one of mercaptopropionic acid, mercaptoacetic acid, and mercaptoacrylic acid; the crosslinking agent is nanoscale silica; and a molar ratio of the monomer comprising both the carboxyl and the sulfhydryl to the crosslinking agent is (1.0-1.6):1.

2. The method for recycling the copper-containing wastewater from the micro-etching according to claim 1, wherein the stabilizing and dispersing agent comprises carboxymethyl cellulose (CMC); a sulfide salt in the sulfide salt solution comprises at least one of sodium sulfide and calcium polysulfide; and the ferrous salt comprises at least one of ferrous sulfate, ferrous ammonium sulfate, ferrous chloride, a ferrous sulfate hydrate, a ferrous ammonium sulfate hydrate, and a ferrous chloride hydrate.

3. The method for recycling the copper-containing wastewater from the micro-etching according to claim 1, wherein a molar ratio of the crosslinking agent to the ferrous salt is 1:(1-3); and a molar ratio of the stabilizing and dispersing agent to the ferrous salt is (5.010.sup.42.010.sup.3):1.

4. The method for recycling the copper-containing wastewater from the micro-etching according to claim 3, wherein a Fe.sup.2+/S.sup.2 molar ratio of the ferrous salt to a sulfide salt in the sulfide salt solution is (1-1.2):1.

5. The method for recycling the copper-containing wastewater from the micro-etching according to claim 1, wherein the heterogeneous precipitation reaction is conducted under oxygen-free conditions.

6. The method for recycling the copper-containing wastewater from the micro-etching according to claim 1, wherein the heterogeneous precipitation reaction is conducted at 25 C. to 35 C. for 60 min to 120 min.

7. The method for recycling the copper-containing wastewater from the micro-etching according to claim 5, wherein the heterogeneous precipitation reaction is conducted at 25 C. to 35 C. for 60 min to 120 min.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of the preparation process of the FeS-based pH-responsive material in the present disclosure, where 1: modified crosslinking agent, 2: stabilizing and dispersing agent, 3: ferrous sulfate solution, 4: sodium sulfide solution, and 5: nitrogen;

(2) FIG. 2 is a scanning electron microscopy (SEM) image of the FeS-based pH-responsive material prepared in Example 1 of the present disclosure;

(3) FIG. 3 is an SEM image of a precipitate produced after copper-containing wastewater from micro-etching is treated with the FeS-based pH-responsive material prepared in Example 1 of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(4) In order to facilitate the understanding of the present disclosure, the present disclosure is described in detail below in conjunction with preferred examples, but the protection scope of the present disclosure is not limited to the following specific examples.

(5) Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are merely for the purpose of describing specific examples, and are not intended to limit the protection scope of the present disclosure.

(6) Unless otherwise specified, various reagents and raw materials used in the present disclosure all are commodities that can be purchased from the market or products that can be prepared by a well-known method.

(7) The FeS-based pH-responsive material used in the examples and comparative examples was prepared through the following steps:

(8) 1) 8 parts by volume of deionized water and 15 parts by volume of absolute ethanol were taken and thoroughly mixed, and a pH was adjusted to 5.5 to obtain a mixed solution.

(9) Mercaptopropionic acid and nanoscale silica (a molar ratio of the mercaptopropionic acid to the nanoscale silica was 1.2:1, and a molar ratio of the nanoscale silica to a ferrous salt was 1:2) were mixed in the above mixed solution and stirred to allow a full crosslinking reaction to produce sulfhydrylated and carboxylated silica.

(10) 2) According to the schematic diagram of the preparation process of the material in FIG. 1: The sulfhydrylated and carboxylated silica as a crosslinking agent and CMC as a stabilizing and dispersing agent were added to a three-necked flask filled with a ferrous sulfate solution (0.6 mol/L, a molar ratio of the stabilizing and dispersing agent to ferrous sulfate was 2.010.sup.3:1), and stirring was conducted at 35 C. in an oxygen-free environment to allow thorough mixing.

(11) Then, the three-necked flask was equipped with a constant-pressure drop funnel in which a sodium sulfide solution of an equal volume to the ferrous sulfate solution (a molar ratio of Fe.sup.2+ to S.sup.2 was 1.1:1) was placed and a three-way glass piston on which an N.sub.2 balloon was arranged.

(12) After an experiment began, the sodium sulfide solution was added dropwise to the three-necked flask by unscrewing a switch of the constant-pressure drop funnel, and a full reaction was allowed for 60 min at 30 C. under magnetic stirring in an oxygen-free environment to produce the FeS-based pH-responsive material.

(13) The wastewater treated in the following examples and comparative examples was high-concentration copper-containing wastewater produced in a production process of a printed circuit board of a specified electronics Co., Ltd. in Jiangsu, namely, copper-containing wastewater from micro-etching. A concentration of each metal element in the wastewater was determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and specific components were shown in Table 1. A content of the metal element after wastewater treatment was shown in Table 1.

(14) TABLE-US-00001 TABLE 1 Composition of a stock solution of the copper- containing wastewater from micro-etching of the specified electronics Co., Ltd. in Jiangsu Element Cu Zn Pb Fe Ni Cr Content 6276.65 14.48 3.58 0.32 0.22 0.14 (mg/L)

Example 1

(15) An appropriate amount of the copper-containing wastewater from micro-etching was taken and added to a reaction vessel, a pH was adjusted to 4.200.05 using a sulfuric acid solution with a volume concentration of 10% and a sodium hydroxide solution with a mass concentration of 20%, the FeS-based pH-responsive material prepared above was added with a molar ratio of S.sup.2 in the material to Cu.sup.2+ in the copper-containing wastewater from micro-etching controlled at 1.2:1, and a reaction was allowed for 20 min.

(16) A precipitate produced after the copper-containing wastewater from micro-etching was treated by the FeS-based pH-responsive material in this example was subjected to energy dispersive spectroscopy (EDS). Results showed that there were C, O, Fe, Cu, and S elements in the precipitate, with weight proportions of 12.48%, 2.34%, 0.85%, 57.46%, and 26.87%, respectively.

Example 2

(17) An appropriate amount of the copper-containing wastewater from micro-etching was taken and added to a reaction vessel, a pH was adjusted to 5.000.05 using a sulfuric acid solution with a volume concentration of 10% and a sodium hydroxide solution with a mass concentration of 20%, the FeS-based pH-responsive material prepared above was added with a molar ratio of S.sup.2 in the material to Cu.sup.2+ in the copper-containing wastewater from micro-etching controlled at 1.2:1, and a reaction was allowed for 20 min.

Example 3

(18) An appropriate amount of the copper-containing wastewater from micro-etching was taken and added to a reaction vessel, a pH was adjusted to 5.800.05 using a sulfuric acid solution with a volume concentration of 10% and a sodium hydroxide solution with a mass concentration of 20%, the FeS-based pH-responsive material prepared above was added with a molar ratio of S.sup.2 in the material to Cu.sup.2+ in the copper-containing wastewater from micro-etching controlled at 1.2:1, and a reaction was allowed for 20 min.

Example 4

(19) An appropriate amount of the copper-containing wastewater from micro-etching was taken and added to a reaction vessel, a pH was adjusted to 5.000.05 using a sulfuric acid solution with a volume concentration of 10% and a sodium hydroxide solution with a mass concentration of 20%, the FeS-based pH-responsive material prepared above was added with a molar ratio of S.sup.2 in the material to Cu.sup.2+ in the copper-containing wastewater from micro-etching controlled at 1:1, and a reaction was allowed for 20 min.

Comparative Example 1

(20) An appropriate amount of the copper-containing wastewater from micro-etching was taken and added to a reaction vessel, a pH was adjusted to 1.000.05 using a sulfuric acid solution with a volume concentration of 10% and a sodium hydroxide solution with a mass concentration of 20%, the FeS-based pH-responsive material prepared above was added with a molar ratio of S.sup.2 in the material to Cu.sup.2+ in the copper-containing wastewater from micro-etching controlled at 1.2:1, and a reaction was allowed for 20 min.

Comparative Example 2

(21) An appropriate amount of the copper-containing wastewater from micro-etching was taken and added to a reaction vessel, a pH was adjusted to 2.000.05 using a sulfuric acid solution with a volume concentration of 10% and a sodium hydroxide solution with a mass concentration of 20%, the FeS-based pH-responsive material prepared above was added with a molar ratio of S.sup.2 in the material to Cu.sup.2+ in the copper-containing wastewater from micro-etching controlled at 1.2:1, and a reaction was allowed for 20 min.

Comparative Example 3

(22) An appropriate amount of the copper-containing wastewater from micro-etching was taken and added to a reaction vessel, a pH was adjusted to 3.000.05 using a sulfuric acid solution with a volume concentration of 10% and a sodium hydroxide solution with a mass concentration of 20%, the FeS-based pH-responsive material prepared above was added with a molar ratio of S.sup.2 in the material to Cu.sup.2+ in the copper-containing wastewater from micro-etching controlled at 1.2:1, and a reaction was allowed for 20 min.

Comparative Example 4

(23) An appropriate amount of the copper-containing wastewater from micro-etching was taken and added to a reaction vessel, a pH was adjusted to 7.000.05 using a sulfuric acid solution with a volume concentration of 10% and a sodium hydroxide solution with a mass concentration of 20%, the FeS-based pH-responsive material prepared above was added with a molar ratio of S.sup.2 in the material to Cu.sup.2+ in the copper-containing wastewater from micro-etching controlled at 1.2:1, and a reaction was allowed for 20 min.

(24) A solution produced after the treatment in each of Examples 1 to 4 and Comparative Examples 1 to 4 was filtered to obtain a filtrate and a precipitate with CuS as a main component. A concentration of residual Cu.sup.2+ in the filtrate was determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), as shown in Table 2.

(25) TABLE-US-00002 TABLE 2 Metal element content after the copper-containing wastewater from micro-etching is treated [S.sup.2]: Cu.sup.2+(mg/ Cu.sup.2+ recovery Examples pH [Cu.sup.2+] L) rate (%) Example 1 4.20 0.05 1.2:1.0 1.15 99.82 Example 2 5.00 0.05 1.2:1.0 0.45 99.93 Example 3 5.80 0.05 1.2:1.0 0.96 99.85 Example 4 5.00 0.05 1.0:1.0 43.52 99.31 Comparative 1.00 0.05 1.2:1.0 280.24 56.21 Example 1 Comparative 2.00 0.05 1.2:1.0 220.05 65.62 Example 2 Comparative 3.00 0.05 1.2:1.0 93.36 85.41 Example 3 Comparative 7.00 0.05 1.2:1.0 157.36 75.41 Example 4

(26) According to the comparison of data of the examples and comparative examples in Table 2: When the copper-containing wastewater from micro-etching is treated with the FeS-based pH-responsive material of the present disclosure at a pH value of 3.95 to 6.05, a content of copper ions in the treated copper-containing wastewater from micro-etching is low, and a recovery rate of copper ions is 99.8% or more. When a pH of a solution system is too low or too high, a recovery effect of the FeS-based pH-responsive material for copper ions is greatly reduced.