Treatment process of wastewater containing heavy metals

Abstract

The invention discloses a heavy metal-containing wastewater treatment process, and belongs to the technical field of wastewater treatment, the heavy metal-containing wastewater treatment process mainly comprises three steps of alkali pretreatment, ultrasonic treatment and heavy metal wastewater treatment agent adsorption treatment, and the heavy metal wastewater treatment agent is PPS ion exchange fiber loaded hydrotalcite. The alkali pretreatment can firstly precipitate and remove some free heavy metal ions which are easy to precipitate, and the ultrasonic treatment can accelerate the decomposition of complex heavy metals, so that the combined heavy metal ions are released to be more thoroughly removed. The PPS ion exchange fiber loaded hydrotalcite can effectively expand the adsorption area and optimize the mass transfer efficiency. And moreover, an amino polycarboxylic acid compound can be intercalated and compounded in the hydrotalcite, so that complex-state heavy metal ions in original wastewater can be snapped, and the heavy metal ions in various forms can be effectively removed.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a treatment process for heavy metal-containing wastewater. Background Art

[0002] During the process of industrial production activities, various heavy metal elements play an important role, especially in the metal smelting industry, machinery manufacturing industry, and mining industry. However, when these heavy metal wastes are mixed with industrial wastewater, heavy metal wastewater will be formed. Some enterprises' excessive and uncontrolled discharge of heavy metal-containing wastewater will cause serious damage to the water environment, leading to the breakdown of the original ecological balance. At the same time, heavy metals are extremely difficult to degrade. When discharged into the natural water circulation system or the soil ecological system, they will continue to exhibit toxicity for several years or even decades in the future. These heavy metals are absorbed by crops and then enter the human body through the enrichment effect, which will endanger human health. Therefore, the treatment effect of heavy metal-containing wastewater is related to the balance of the ecological system and the survival and development of humans.

[0003] However, as the types of heavy metals in the water environment are also increasing, some traditional water treatment methods, including membrane separation, adsorption, electrochemistry, etc., are more difficult to treat heavy metal wastewater. Moreover, these traditional water treatment methods have problems such as complex operation, being easily affected by external factors, unstable treatment effect, and high energy consumption, which all limit the treatment scope of heavy metal wastewater to a certain extent.

[0004] At the same time, generally most heavy metals exist in the form of free state in the wastewater. At this time, traditional treatment methods can achieve a certain degree of removal. However, some heavy metals may also exist in the form of complex state in the wastewater. This kind of heavy metal in complex state is difficult to treat, and it is difficult to remove it from the wastewater by general treatment methods. Therefore, obtaining a process method for efficiently removing heavy metals from heavy metal-containing wastewater is of great significance for the future development of the industry. Summary of the Invention

[0005] The purpose of the present invention is to provide a treatment method for heavy metal-containing wastewater to solve the problem of poor removal effect of heavy metals in heavy metal-containing wastewater.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] The present invention provides a treatment process for heavy metal-containing wastewater, including the following process steps:

[0008] S1. Add a pH regulator to the heavy metal-containing wastewater to adjust the pH value of the wastewater to 8 - 10;

[0009] S2. Filter and remove insoluble substances to obtain a pretreated solution;

[0010] S3. Perform ultrasonic treatment on the pretreated solution;

[0011] S4. Add a heavy metal wastewater treatment agent to the pretreated solution after ultrasonic treatment, stir and react, and remove the precipitate after sedimentation separation;

[0012] The heavy metal wastewater treatment agent is PPS ion exchange fiber loaded with hydrotalcite.

[0013] Preferably, the pH regulator includes one or a combination of more of sodium hydroxide, calcium hydroxide, sodium carbonate, and magnesium hydroxide.

[0014] Preferably, the ultrasonic frequency of the ultrasonic treatment is 35 - 50 kHz, and the power is 100 - 200 W.

[0015] Preferably, the dosage of the heavy metal wastewater treatment agent is 5 - 10 mg / L.

[0016] By adopting the above technical solution, the present invention first adjusts the pH value of the heavy metal-containing wastewater. Under the action of the pH regulator, the heavy metal ions in the wastewater can form insoluble metal hydroxide precipitates with the hydroxide ions in the alkaline environment, and can pre-treat the heavy metal-containing wastewater to remove part of the free heavy metal ions, facilitating the subsequent treatment process.

[0017] Then, ultrasonic treatment is performed on the pretreated solution. Since there may be ligands such as cyanide and ammonia in the wastewater, which will form soluble complexes with heavy metal ions, and such complexed heavy metals are difficult to directly remove by conventional methods, the pretreated solution is first subjected to ultrasonic treatment. Ultrasonic waves can effectively break the bonding between metal ions and ligands in the complex. When ultrasonic waves propagate in the pretreated solution, cavitation occurs. The tiny bubbles formed will generate a local high-temperature and high-pressure environment at the moment of rupture, which can accelerate the decomposition of complexed heavy metals, enabling the release and more thorough removal of heavy metal ions that are difficult to remove or bind. And the cavitation effect of ultrasonic waves will also generate strongly oxidizing groups such as hydroxyl radicals, and these highly active groups can react with various organic pollutants to help better treat the wastewater.

[0018] Finally, add a heavy metal wastewater treatment agent, namely PPS ion exchange fiber loaded with hydrotalcite, to the pretreated solution after ultrasonic treatment. The polar groups contained in PPS (polyphenylene sulfide) ion exchange fiber can help form stable chemical bonds with heavy metal ions, thereby realizing the selective adsorption of heavy metal ions. And PPS ion exchange fiber can also undergo surface complexation with heavy metal ions through electrostatic attraction and the like, thereby improving the adsorption and removal of heavy metal ions.

[0019] However, due to the relatively low molecular weight of the PPS ion-exchange fiber itself and its rigid structure, the ion-exchange capacity is low. Moreover, in wastewater containing multiple heavy metal ions, competitive adsorption occurs between ions. Since the number of active sites on the surface of the PPS ion-exchange fiber is not large enough, it will interfere with the adsorption of other heavy metal ions and affect the removal process of heavy metal ions.

[0020] Therefore, hydrotalcite is loaded on the PPS ion-exchange fiber. Hydrotalcite itself has abundant anion-exchange sites. When loaded on the PPS ion-exchange fiber, it is equivalent to adding additional adsorption sites, greatly expanding the available adsorption space of the heavy metal wastewater treatment agent. Moreover, the layered structure of hydrotalcite can effectively improve the pore structure inside the PPS ion-exchange fiber, which is more conducive to the diffusion of heavy metal ions into the channels inside the heavy metal wastewater treatment agent. While optimizing the mass transfer efficiency, it increases the effective adsorption area of the heavy metal wastewater treatment agent. The two cooperate synergistically to effectively remove heavy metal ions in heavy metal-containing wastewater.

[0021] Preferably, the raw materials of the heavy metal wastewater treatment agent include PPS ion-exchange fiber and hydrotalcite precursor with a molar ratio of 1:(0.2 - 0.4).

[0022] Preferably, the hydrotalcite precursor is zinc nitrate hexahydrate and aluminum nitrate nonahydrate with a molar ratio of 2:(0.9 - 1.05).

[0023] Preferably, the raw materials of the PPS ion-exchange fiber include PPS fiber, cross-linking agent, sulfonating agent, and amino-silane coupling agent with a molar ratio of 1:(0.5 - 0.6):(1.2 - 1.5):(0.3 - 0.5).

[0024] More preferably, the cross-linking agent includes one or a combination of more of formaldehyde, trioxane, paraformaldehyde, hydrochloric acid, chloromethyl methyl ether, dichloromethyl ether, and chloromethyl alkyl ether.

[0025] More preferably, the sulfonating agent includes one or a combination of more of sulfur trioxide, concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, and sulfamic acid.

[0026] More preferably, the amino-silane coupling agent includes one or a combination of more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)-γ-aminopropyltriethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldiethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, phenylaminomethyltriethoxysilane, and phenylaminomethyltrimethoxysilane.

[0027] More preferably, the PPS ion-exchange fiber is prepared by the following method:

[0028] The PPS fibers are subjected to a swelling treatment, a crosslinking agent and a catalyst are added, the solution temperature is adjusted to 40-55 °C, and the mixture is stirred and reacted for 10-15 h, and then the crosslinked PPS fibers are obtained after washing and drying.

[0029] The crosslinked PPS fibers are continuously subjected to a swelling treatment, a sulfonating agent and an amino-silane coupling agent are added, and under a nitrogen atmosphere, the temperature is raised to 65-75 °C, and the mixture is stirred and reacted for 7-8 h, and finally the PPS ion exchange fibers are obtained after washing and drying.

[0030] More preferably, the solvent used for the swelling treatment includes any one of 1,2-dichloroethane, nitrobenzene, carbon tetrachloride and chloroform.

[0031] By adopting the above technical solution, the PPS ion exchange fibers of the present invention are subjected to crosslinking and amino-sulfonation treatment. The crosslinking treatment can effectively improve the problems that the PPS fibers are prone to excessive swelling and dissolution loss during the sulfonation process, provide more mass transfer channels for the heavy metal wastewater treatment agent, and increase the effective area; after amino and sulfonation, more active functional groups are introduced onto the PPS fibers, and the sulfonic acid groups can effectively complex heavy metal ions to form stable chemical bonds, thereby removing heavy metal ions in the wastewater. And after amino treatment, the binding force between the hydrotalcite and the PPS ion exchange fibers can be improved, and the shedding of the hydrotalcite under the influence of external environmental factors during use can be reduced, thereby affecting the removal efficiency of heavy metal ions.

[0032] And the PPS ion exchange fibers mainly capture heavy metal ions through sulfonic acid groups, and the supported hydrotalcite mainly reacts with heavy metal ions through the exchangeable anions between the layers. The insoluble precipitates formed by the heavy metal ions captured by the PPS ion exchange fibers or can be directly exchanged into the interlayer pores of the hydrotalcite. The two cooperate synergistically to effectively remove various types of heavy metal ions.

[0033] Moreover, the layers of the hydrotalcite carry positive charges, and exchangeable anions exist between the layers. These anions can be exchanged with the heavy metal complex anions in the solution, so that the heavy metal ions are captured and fixed, thereby supplementing the problem of insufficient selective adsorption capacity of the PPS ion exchange fibers.

[0034] Preferably, the raw materials of the heavy metal wastewater treatment agent further include amino polycarboxylic acid compounds; the molar ratio of the amino polycarboxylic acid compounds to the PPS ion exchange fibers is (0.1-0.2):1.

[0035] Preferably, the amino polycarboxylic acid compounds include one or a combination of more of nitrilotriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, hydroxyethylidene diphosphonic acid and iminodiacetic acid.

[0036] By adopting the above technical solution, after ultrasonic treatment, the content of complex heavy metals in the heavy metal-containing wastewater has decreased significantly. However, there are still some heavy metal ions that combine with ligands again to form complexes. Therefore, an aminopolycarboxylic acid compound is also added to the raw materials of the heavy metal wastewater treatment agent.

[0037] The aminopolycarboxylic acid compound is a strong competitive ligand for heavy metal ions. The abundant nitrogen atoms and carboxyl groups it contains can simultaneously provide hard basic oxygen donors and soft basic nitrogen donors, which can be applicable to the coordination of different types of heavy metal ions, seize the complex heavy metal ions in the original wastewater, and tightly combine with the target metal ions in various ways such as carbon-nitrogen bonds or carbon-oxygen bonds, thus forming a highly stable chelate ring structure, effectively adsorbing and dissociating the complex heavy metals in the wastewater, so as to achieve the effective removal of heavy metal ions.

[0038] Preferably, the heavy metal wastewater treatment agent is prepared by the following method:

[0039] Soak the PPS ion exchange fiber in deionized water, add the hydrotalcite precursor solution, mix for 30 - 60 min, add the precipitant, after mixing evenly, add the aminopolycarboxylic acid compound, under a nitrogen atmosphere, control the reaction pH value to be 9 - 10, the reaction temperature to be 35 - 40 °C, stir and react for 10 - 15 h, and finally after washing and drying, calcine at 350 - 400 °C for 3 - 4 h to obtain the heavy metal wastewater treatment agent.

[0040] Preferably, the precipitant includes one or a combination of two of sodium hydroxide and sodium carbonate.

[0041] By adopting the above technical solution, in the present invention, the PPS ion exchange fiber is soaked in the hydrotalcite precursor solution, and the hydrotalcite precursor can enter the interior of the PPS ion exchange fiber, thereby maximizing the improvement of its internal pore structure and effective adsorption area, and increasing the adsorption capacity of the obtained heavy metal wastewater treatment agent.

[0042] Then, after adding the precipitant, an aminopolycarboxylic acid compound is added. The aminopolycarboxylic acid compound is intercalated and compounded in the hydrotalcite. On the one hand, the aminopolycarboxylic acid compound can provide various coordination mechanisms, improving the removal efficiency of the heavy metal wastewater treatment agent for complex-bound heavy metals; on the other hand, the intercalation and compounding of the aminopolycarboxylic acid compound can also increase the layer spacing of the hydrotalcite, which is not only conducive to the entry and bonding reaction of heavy metal ions, but also promotes the internal diffusion process, improving the adsorption efficiency and capacity of the heavy metal wastewater treatment machine. At the same time, the hydrotalcite after intercalation and compounding has more exchangeable anion sites, realizing the immobilization of heavy metal ions. The synergistic capture effect of PPS ion exchange fibers can efficiently remove various forms and types of heavy metal ions in heavy metal-containing wastewater.

[0043] Advantages of the present invention:

[0044] 1. The treatment process of heavy metal-containing wastewater of the present invention mainly includes three major steps: alkali pretreatment - ultrasonic treatment - adsorption treatment with a heavy metal wastewater treatment agent. Among them, alkali pretreatment can first precipitate and remove some easily precipitated free heavy metal ions, facilitating subsequent treatment processes; ultrasonic treatment mainly utilizes the cavitation effect of ultrasonic waves to accelerate the decomposition of complex-bound heavy metals, so that the combined heavy metal ions can be released for more thorough removal.

[0045] 2. In the adsorption treatment process of the heavy metal wastewater treatment agent of the present invention, the heavy metal wastewater treatment agent used is PPS ion exchange fiber loaded with hydrotalcite. The sulfonic acid groups contained in the PPS ion exchange fiber can capture complex heavy metal ions, realizing the adsorption and removal of heavy metal ions; loading with hydrotalcite can effectively expand the adsorption capacity of the PPA ion exchange fiber, while optimizing the mass transfer efficiency, increasing the effective adsorption area of the heavy metal wastewater treatment agent. And more preferably, an aminopolycarboxylic acid compound is intercalated and compounded in the hydrotalcite, which can capture the complex-bound heavy metal ions in the original wastewater, realizing the effective removal of heavy metal ions in various forms. Specific embodiments

[0046] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0047] Preparation examples

[0048] Preparation example 1, a heavy metal wastewater treatment agent, is prepared according to the following method:

[0049] The PPS fibers were added to 1,2-dichloroethane for swelling treatment, then chloromethyl methyl ether and anhydrous stannic chloride were added. The temperature of the solution was adjusted to 50 °C and stirred for reaction for 12 h, and then crosslinked PPS fibers were obtained after washing and drying;

[0050] The crosslinked PPS fibers were continuously added to 1,2-dichloroethane for swelling treatment, then chlorosulfonic acid and γ-aminopropyltriethoxysilane were added. Under a nitrogen atmosphere, the temperature was raised to 70 °C and stirred for reaction for 8 h. Finally, PPS ion exchange fibers were obtained after washing and drying; the molar ratio of PPS fibers, chloromethyl methyl ether, chlorosulfonic acid and γ-aminopropyltriethoxysilane was 1:0.5:1.4:0.4.

[0051] The obtained PPS ion exchange fibers were soaked in deionized water, and a solution of a hydrotalcite precursor (a mixture of zinc nitrate hexahydrate and aluminum nitrate nonahydrate with a molar ratio of 2:1) with a mass fraction of 20% was added, and they were mixed for 60 min. Then a precipitating agent (a mixture of sodium hydroxide and sodium carbonate with a mass ratio of 1:1) was added, and the molar ratio of the precipitating agent to the hydrotalcite precursor was 1:0.5. After mixing evenly, diethylenetriaminepentaacetic acid was added. Under a nitrogen atmosphere, the reaction pH value was controlled to be 10, the reaction temperature was 35 °C, and stirred for reaction for 15 h. Finally, after washing and drying, it was calcined at 350 °C for 4 h to obtain a heavy metal wastewater treatment agent. The molar ratio of PPS ion exchange fibers, hydrotalcite precursor and diethylenetriaminepentaacetic acid was 1:0.3:0.15.

[0052] Preparation Example 2, a heavy metal wastewater treatment agent, the difference from Example 1 was only that the molar ratio of PPS fibers, chloromethyl methyl ether, chlorosulfonic acid and γ-aminopropyltriethoxysilane was 1:0.6:1.5:0.5.

[0053] Preparation Example 3, a heavy metal wastewater treatment agent, the difference from Example 1 was only that the molar ratio of PPS fibers, chloromethyl methyl ether, chlorosulfonic acid and γ-aminopropyltriethoxysilane was 1:0.5:1.2:0.3.

[0054] Preparation Example 4, a heavy metal wastewater treatment agent, the difference from Example 1 was only that the molar ratio of PPS ion exchange fibers, hydrotalcite precursor and diethylenetriaminepentaacetic acid was 1:0.2:0.1.

[0055] Preparation Example 5, a heavy metal wastewater treatment agent, the difference from Example 1 was only that the molar ratio of PPS ion exchange fibers, hydrotalcite precursor and diethylenetriaminepentaacetic acid was 1:0.4:0.2.

[0056] Preparation Example 6, a heavy metal wastewater treatment agent, the difference from Example 1 was only that the molar ratio of PPS ion exchange fibers to hydrotalcite precursor was 1:0.1.

[0057] Preparation Example 7, a heavy metal wastewater treatment agent, which is different from Example 1 only in that the molar ratio of PPS ion exchange fiber to hydrotalcite precursor is 1:0.5.

[0058] Preparation Example 8, a heavy metal wastewater treatment agent, which is different from Example 1 only in that the molar ratio of PPS ion exchange fiber to diethylenetriaminepentaacetic acid is 1:0.05.

[0059] Preparation Example 9, a heavy metal wastewater treatment agent, which is different from Example 1 only in that the molar ratio of PPS ion exchange fiber to diethylenetriaminepentaacetic acid is 1:0.25.

[0060] Preparation Example 10, a heavy metal wastewater treatment agent, which is different from Example 1 only in that in the preparation process of the heavy metal wastewater treatment agent, it is prepared according to the following method:

[0061] Soak the obtained PPS ion exchange fiber in deionized water, add a solution of hydrotalcite precursor with a mass fraction of 20% (a mixture of zinc nitrate hexahydrate and aluminum nitrate nonahydrate with a molar ratio of 2:1), mix for 60 min, add a precipitant (a mixture of sodium hydroxide and sodium carbonate with a mass ratio of 1:1), the molar ratio of the precipitant to the hydrotalcite precursor is 1:0.5, under a nitrogen atmosphere, control the reaction pH value to be 10, the reaction temperature is 35 °C, stir and react for 15 h, and finally after washing and drying, calcine at 350 °C for 4 h to obtain the heavy metal wastewater treatment agent. The molar ratio of PPS ion exchange fiber to hydrotalcite precursor is 1:0.3.

[0062] Preparation Example 11, a heavy metal wastewater treatment agent, which is different from Example 1 only in that in the preparation process of the PPS ion exchange fiber, it is prepared according to the following method:

[0063] Add PPS fiber to 1,2-dichloroethane for swelling treatment, add chloromethyl ether and anhydrous stannic chloride, adjust the solution temperature to 50 °C, stir and react for 12 h, and then obtain crosslinked PPS fiber after washing and drying;

[0064] Continue to add the crosslinked PPS fiber to 1,2-dichloroethane for swelling treatment, add chlorosulfonic acid, under a nitrogen atmosphere, raise the temperature to 70 h, stir and react for 8 h, and finally obtain PPS ion exchange fiber after washing and drying; the molar ratio of PPS fiber, chloromethyl ether and chlorosulfonic acid is 1:0.5:1.4.

[0065] Preparation Example 12, a heavy metal wastewater treatment agent, which is different from Example 1 only in that in the preparation process of the heavy metal wastewater treatment agent, it is prepared according to the following method:

[0066] The obtained PPS ion-exchange fiber was immersed in deionized water, and diethylenetriaminepentaacetic acid was added. Under a nitrogen atmosphere, the reaction pH value was controlled to be 10, the reaction temperature was 35 °C, and the reaction was stirred for 15 h. Finally, after washing and drying, a heavy metal wastewater treatment agent was obtained. The molar ratio of PPS ion-exchange fiber to diethylenetriaminepentaacetic acid was 1:0.15.

[0067] Preparation Example 13, a heavy metal wastewater treatment agent, which is different from Example 1 only in that it is prepared according to the following method:

[0068] The PPS fiber was added to 1,2-dichloroethane for swelling treatment, chloromethyl ether and anhydrous stannic chloride were added, the solution temperature was adjusted to 50 °C, and the reaction was stirred for 12 h. Then, after washing and drying, crosslinked PPS fiber was obtained;

[0069] The crosslinked PPS fiber was continuously added to 1,2-dichloroethane for swelling treatment, chlorosulfonic acid and γ-aminopropyltriethoxysilane were added. Under a nitrogen atmosphere, the temperature was raised to 70 °C, and the reaction was stirred for 8 h. Finally, after washing and drying, PPS ion-exchange fiber was obtained; the molar ratio of PPS fiber, chloromethyl ether, chlorosulfonic acid and γ-aminopropyltriethoxysilane was 1:0.5:1.4:0.4. The obtained PPS ion-exchange fiber is the heavy metal wastewater treatment agent.

[0070] Example

[0071] Example 1, a treatment process for heavy metal-containing wastewater, comprising the following process steps:

[0072] S1. Calcium hydroxide was added to the heavy metal-containing wastewater to adjust the pH value of the wastewater to 10;

[0073] S2. The insoluble substances were removed by filtration to obtain a pretreatment solution;

[0074] S3. The pretreatment solution was subjected to ultrasonic treatment, wherein the ultrasonic frequency of the ultrasonic wave was 45 kHz and the power was 150 W;

[0075] S4. The heavy metal wastewater treatment agent prepared in Preparation Example 1 was added to the pretreated solution after ultrasonic treatment, wherein the dosage of the heavy metal wastewater treatment agent was 8 mg / L; the reaction was stirred, and the precipitate was removed after sedimentation separation.

[0076] Example 2, a treatment process for heavy metal-containing wastewater, which is different from Example 1 only in that the heavy metal wastewater treatment agent prepared in Preparation Example 2 was used to replace the heavy metal wastewater treatment agent prepared in Preparation Example 1 in equal amount.

[0077] Example 3. A treatment process for heavy metal-containing wastewater, which is only different from Example 1 in that the heavy metal wastewater treatment agent prepared in Preparation Example 3 is used to replace the heavy metal wastewater treatment agent prepared in Preparation Example 1 in equal amount.

[0078] Example 4. A treatment process for heavy metal-containing wastewater, which is only different from Example 1 in that the heavy metal wastewater treatment agent prepared in Preparation Example 4 is used to replace the heavy metal wastewater treatment agent prepared in Preparation Example 1 in equal amount.

[0079] Example 5. A treatment process for heavy metal-containing wastewater, which is only different from Example 1 in that the heavy metal wastewater treatment agent prepared in Preparation Example 5 is used to replace the heavy metal wastewater treatment agent prepared in Preparation Example 1 in equal amount.

[0080] Example 6. A treatment process for heavy metal-containing wastewater, which is only different from Example 1 in that the heavy metal wastewater treatment agent prepared in Preparation Example 6 is used to replace the heavy metal wastewater treatment agent prepared in Preparation Example 1 in equal amount.

[0081] Example 7. A treatment process for heavy metal-containing wastewater, which is only different from Example 1 in that the heavy metal wastewater treatment agent prepared in Preparation Example 7 is used to replace the heavy metal wastewater treatment agent prepared in Preparation Example 1 in equal amount.

[0082] Example 8. A treatment process for heavy metal-containing wastewater, which is only different from Example 1 in that the heavy metal wastewater treatment agent prepared in Preparation Example 8 is used to replace the heavy metal wastewater treatment agent prepared in Preparation Example 1 in equal amount.

[0083] Example 9. A treatment process for heavy metal-containing wastewater, which is only different from Example 1 in that the heavy metal wastewater treatment agent prepared in Preparation Example 9 is used to replace the heavy metal wastewater treatment agent prepared in Preparation Example 1 in equal amount.

[0084] Example 10. A treatment process for heavy metal-containing wastewater, which is only different from Example 1 in that the heavy metal wastewater treatment agent prepared in Preparation Example 10 is used to replace the heavy metal wastewater treatment agent prepared in Preparation Example 1 in equal amount.

[0085] Example 11. A treatment process for heavy metal-containing wastewater, which is only different from Example 1 in that the heavy metal wastewater treatment agent prepared in Preparation Example 11 is used to replace the heavy metal wastewater treatment agent prepared in Preparation Example 1 in equal amount.

[0086] Comparative Example

[0087] Comparative Example 1. A treatment process for heavy metal-containing wastewater, which is only different from Example 1 in that the heavy metal wastewater treatment agent prepared in Preparation Example 12 is used to replace the heavy metal wastewater treatment agent prepared in Preparation Example 1 in equal amount.

[0088] Comparative Example 2, a treatment process for heavy metal-containing wastewater, is different from Example 1 only in that the heavy metal wastewater treatment agent prepared in Preparation Example 13 is used to replace the heavy metal wastewater treatment agent prepared in Preparation Example 1 in equal amounts.

[0089] Comparative Example 3, a treatment process for heavy metal-containing wastewater, comprises the following process steps:

[0090] S1. Adding calcium hydroxide to the heavy metal-containing wastewater to adjust the pH value of the wastewater to 10;

[0091] S2. Filtering to remove insoluble substances to obtain a pretreatment solution;

[0092] S3. Adding the heavy metal wastewater treatment agent prepared in Preparation Example 1 to the pretreatment solution, wherein the dosage of the heavy metal wastewater treatment agent is 8 mg / L; stirring and reacting, and removing the precipitate after sedimentation and separation.

[0093] Comparative Example 3, a treatment process for heavy metal-containing wastewater, comprises the following process steps:

[0094] S1. Subjecting the heavy metal-containing wastewater to ultrasonic treatment, wherein the ultrasonic frequency of the ultrasonic wave is 45 kHz and the power is 150 W;

[0095] S2. Adding the heavy metal wastewater treatment agent prepared in Preparation Example 1 to the heavy metal-containing wastewater after ultrasonic treatment, wherein the dosage of the heavy metal wastewater treatment agent is 8 mg / L; stirring and reacting, and removing the precipitate after sedimentation and separation.

[0096] Performance detection test

[0097] Taking industrial heavy metal-containing wastewater, and measuring the contents of heavy metal elements in the heavy metal-containing wastewater before and after treatment according to the relevant records in HJ 700-2014 "Determination of 65 Elements in Water Quality - Inductively Coupled Plasma Mass Spectrometry" and HJ 694-2014 "Determination of Mercury, Arsenic, Selenium, Bismuth and Antimony in Water Quality - Atomic Fluorescence Spectrometry".

[0098] Before measurement, the heavy metal-containing wastewater contains 11.8 mg / L of lead, 4.5 mg / L of copper, and 51.4 mg / L of nickel, and then the removal rates of various heavy metal elements after treatment in each example and comparative example are calculated.

[0099] The above test results are shown in Table 1:

[0100] Table 1 Heavy metal removal test results

[0101]

[0102] According to Table 1, in combination with Example 1 and Example 10, it can be seen that the removal rate of copper ions in the wastewater after treatment in Example 10 has decreased compared with that in Example 1. The reason is that copper ions are very likely to form complexes with ligands in the wastewater and exist in the heavy metal-containing wastewater in the form of complex state. The difference between Example 10 and Example 1 is only that there is no composite aminopolycarboxylic acid compound between the interlayers of the hydrotalcite carried by the PPS ion exchange fiber, resulting in a decrease in the ability of the obtained heavy metal wastewater treatment agent to treat complex heavy metals.

[0103] In combination with Example 1 and Example 11, it can be seen that the removal rate of each heavy metal element in Example 11 has decreased compared with that in Example 1. The reason is that during the preparation of the PPS ion exchange fiber used in Example 11, no aminosilane coupling agent was added for treatment, resulting in a decrease in the binding force with the hydrotalcite during the process of carrying the hydrotalcite, and the hydrotalcite is likely to fall off during the reaction sedimentation process, resulting in a decrease in the ability of the heavy metal wastewater treatment agent to remove heavy metal ions.

[0104] In combination with Example 1 and Comparative Example 1, it can be seen that the removal rate of each heavy metal element in Comparative Example 1 has decreased significantly compared with that in Example 1. The reason is that the difference between Comparative Example 1 and Example 1 is only that the PPS ion exchange fiber does not carry the hydrotalcite, and the aminopolycarboxylic acid compound is directly grafted on the surface of the PPS ion exchange fiber. On the one hand, the lack of the expansion of the adsorption capacity of the PPS ion exchange fiber by the hydrotalcite leads to a decrease in the adsorption capacity of the heavy metal wastewater treatment agent. On the other hand, the direct grafting of the aminopolycarboxylic acid compound will directly compete for the active adsorption sites on the surface of the PPS ion exchange fiber, thus greatly reducing the adsorption and capture ability of the heavy metal wastewater treatment agent for heavy metal ions.

[0105] In combination with Example 1 and Comparative Example 2, it can be seen that the removal rate of each heavy metal element in Comparative Example 2 has decreased significantly compared with that in Example 1. The reason is that in Comparative Example 2, the PPS ion exchange fiber does not carry the hydrotalcite and no aminopolycarboxylic acid compound is added for modification treatment, resulting in a significant decrease in the adsorption capacity of the PPS ion exchange fiber and a lack of synergistic effect with the hydrotalcite, and the removal effect of heavy metal ions has decreased significantly.

[0106] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0107] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for treating wastewater containing heavy metals, characterized in that: The process steps include: S1. Add pH regulator to the heavy metal-containing wastewater to adjust the pH value of the wastewater to 8-10; S2. Filter and remove the insoluble matter to obtain a pretreated solution; S3. Ultrasonic treatment of the pretreatment liquid; S4. Adding a heavy metal wastewater treatment agent to the pre-treated solution after ultrasonic treatment, stirring the reaction, and removing the precipitate after sedimentation separation; The heavy metal wastewater treatment agent is PPS ion exchange fiber loaded with hydrotalcite.

2. The process for treating heavy metal-containing wastewater according to claim 1, characterized in that: The raw materials of the heavy metal wastewater treatment agent include PPS ion exchange fiber and hydrotalcite precursor in a molar ratio of 1: (0.2-0.4).

3. The process for treating heavy metal-containing wastewater according to claim 2, characterized in that: The hydrotalcite precursor is zinc nitrate hexahydrate and aluminum nitrate nonahydrate in a molar ratio of 2: (0.9-1.05).

4. The process for treating heavy metal-containing wastewater according to claim 2, characterized in that: The raw materials of the PPS ion exchange fiber include PPS fiber, a crosslinking agent, a sulfonating agent and an aminosilane coupling agent in a molar ratio of 1: (0.5-0.6): (1.2-1.5): (0.3-0.5).

5. The process for treating heavy metal-containing wastewater according to claim 2, characterized in that: The raw materials of the heavy metal wastewater treatment agent also include aminopolycarboxylic acid compounds; the molar ratio of the aminopolycarboxylic acid compounds to the PPS ion exchange fiber is (0.1-0.2):

1.

6. The heavy metal wastewater treatment process according to claim 5, characterized in that: The aminopolycarboxylic acid compound includes one or more combinations of nitrilotriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, hydroxyethylidene diphosphonic acid and iminodiacetic acid.

7. The process for treating heavy metal-containing wastewater according to claim 5, characterized in that: The heavy metal wastewater treatment agent is prepared according to the following method: The PPS ion exchange fiber is soaked in deionized water, a hydrotalcite precursor solution is added, and the mixture is mixed for 30 to 60 minutes. A precipitant is added, and after uniform mixing, an aminopolycarboxylic acid compound is added. Under a nitrogen atmosphere, the reaction pH value is controlled to be 9 to 10, the reaction temperature is 35 to 40° C., the reaction is stirred for 10 to 15 hours, and finally, after washing and drying, the mixture is calcined at 350 to 400° C. for 3 to 4 hours to obtain a heavy metal wastewater treatment agent.

8. The process for treating heavy metal-containing wastewater according to claim 7, characterized in that: The precipitant includes one or a combination of sodium hydroxide and sodium carbonate.

9. The process for treating heavy metal-containing wastewater according to claim 1, characterized in that: The pH adjuster includes a combination of one or more of sodium hydroxide, calcium hydroxide, sodium carbonate and magnesium hydroxide.

10. The process for treating heavy metal-containing wastewater according to claim 1, characterized in that: The ultrasonic treatment has an ultrasonic frequency of 35 to 50 kHz and a power of 100 to 200 W.

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