CN102659231B - Preparation and application of water-soluble macromolecule heavy-metal collector - Google Patents

Abstract

The invention relates to the preparation and application of a water-soluble macromolecular heavy metal trapping agent, which belongs to the technical field of preparation of functionalized polymer materials and treatment of wastewater containing heavy metals. The invention discloses a preparation method of a water-soluble macromolecular heavy metal scavenger. Two small molecular amines ethylenediamine and triethylenetetramine are cross-linked to form a macromolecular skeleton, and then grafted on the macromolecular skeleton with two Thiocarbamic acid groups generate a macromolecular water-soluble heavy metal trapping agent. This kind of heavy metal collector can not only chelate heavy metal ions, but also has the effect of net flocculation. The particles are large, the structure is compact, and the sedimentation speed is fast. The applicable range of heavy metal ions is wide, and the pH range is wide from 1 to 9. The removal rate of heavy metal ions in water is high, which can reach more than 95%.

Description

Preparation and application of a water-soluble macromolecular heavy metal collector

technical field

Preparation and application of a water-soluble macromolecular heavy metal trapping agent, the invention relates to the preparation of a water-soluble macromolecular heavy metal trapping agent, which can be used for the trapping, flocculation, and removal of heavy metal ions in industrial wastewater, so as to achieve the environmental protection of polymer materials purpose of the domain application. The invention relates to the technical fields of preparation of functional polymer materials and environmental protection, and particularly belongs to the field of waste water treatment containing heavy metal ions.

Background technique

With the production of more and more new materials and the increase of organic additives, the composition of heavy metal wastewater is becoming more and more complex, and the difficulty of treatment is also increasing. Traditional methods such as neutralization and precipitation, vulcanization, ion exchange, reverse osmosis and adsorption, etc. Due to the problems of long treatment process, harsh treatment conditions, difficult disposal of waste residue, high cost, introduction of secondary pollution, and limited treatment capacity, it cannot meet the current needs. Especially when there are chelating agents in the wastewater, such as halogens, cyanide, humus, citric acid, EDTA, etc., heavy metal ions coordinate with them to form complexes, and the above methods cannot effectively remove them.

In today's increasingly serious environmental pollution, dithiocarbamate (DTC) compounds have become a research hotspot in the field of pollution control due to their strong complexation ability with metal ions. Moriya M. et al. (U. S. Pat: 4731187, 1988) mixed low molecular weight DTC with sodium sulfide and sodium polysulfide in a certain proportion and used them in wastewater treatment to improve the flocculation effect. However, low-molecular-weight recapture agents and sulfides remain in the water, which will cause secondary pollution and increase the total organic carbon content of the discharged water. Werneke M. F. et al. ( Mining Engineering, 1978, 30(1): 72-76) synthesized an alkyl dithiocarbamate heavy metal collector, but its alum flowers are small, toxic, and poor in water solubility. restrict its use.

According to the relationship between the structure and performance of dithiocarbamate, the synthesis of heavy metal collectors that can be widely used is a research direction for environmental protection workers in the future. In addition, improving the stability and water solubility of heavy metal traps, improving the synthesis process, and making the synthesis process develop in a mild and efficient direction will promote the further commercialization of DTC heavy metal traps.

Contents of the invention

The purpose of the present invention is to overcome the defects of the prior art and provide a preparation method of a water-soluble macromolecular heavy metal collector. The present invention cross-links ethylenediamine and triethylenetetramine into a macromolecular skeleton, and then grafts carbon disulfide on the macromolecular skeleton to form a dithiocarbamic acid group, which can be combined with most heavy metal ions in industrial wastewater, such as Cu ²⁺ , Ni ²⁺ , Cd ²⁺ , Hg ²⁺ , Pb ²⁺ , Cr ³⁺ and other rapid complexation reactions, and because it contains a macromolecular skeleton, it also has the effect of netting, forming dense and large flocs The body quickly sank down. Through solid-liquid separation, the purpose of efficiently removing heavy metal ions in water can be achieved.

 The object of the present invention is achieved through the following technical solutions, that is, the preparation method of water-soluble macromolecular heavy metal trapping agent comprises the following steps:

(1) Synthesis of the macromolecular skeleton of the heavy metal scavenger: Dissolve a total of 1 mol of ethylenediamine and triethylenetetramine in 100mL of water, wherein the molar ratio of ethylenediamine:triethylenetetramine is 9~5:1~ 5. Prepare a small molecule amine-water solution; slowly add 1.071mol of epichlorohydrin dropwise into the small molecule amine-water solution, and finish adding within 3 hours, then react at 40°C to 50°C for 3 hours, and let it stand overnight. Do not stir or heat during this time. Pour the above overnight solution into a four-necked flask, and continue to add epichlorohydrin dropwise while stirring, and simultaneously add alkali solution (50%, 0.895mol) dropwise. Epichlorohydrin is added within 6 hours, and the alkali The solution is added within 2 hours, the total amount of epichlorohydrin added: the total molar ratio of small molecular amines is 1.3~1.1:1, stirred and reacted at 70~90°C for 0.5 hours, and then stirred and unheated Under the condition overnight, the product was obtained. Add 50% alkali solution to the above reaction product, mix and stir at room temperature to prepare a 30% aqueous solution to obtain a macromolecular skeleton solution, which is a viscous and transparent yellow liquid. The total amount of alkali solution added: the total amount of epichlorohydrin molar ratio is 1:1.

(2) Grafting dithiocarbamate groups on the macromolecular skeleton: Weigh a certain mass of macromolecular skeleton solution into a three-necked flask, add 50% alkali solution, and the mass ratio of macromolecular skeleton solution:alkaline solution is 1: 1. Add carbon disulfide in an equimolar amount to the alkaline solution in an ice bath, drop it within 15 minutes, then react in an ice bath for 1 hour to prevent carbon disulfide volatilization, and then warm up to room temperature for 30 minutes.

In the above preparation method, it is characterized in that the alkali used in the reaction process is one of potassium hydroxide and sodium hydroxide.

The heavy metal trapping agent prepared by the present invention has the following characteristics:

(1) The heavy metal trapping agent prepared by the present invention has good water solubility, the solubility reaches 20g/100g water at 25°C, and can fully react with heavy metal ions in water;

(2) The heavy metal trapping agent prepared by the present invention has a wide pH range, and can be used within the range of pH 1-9;

(3) The raw materials used in the present invention are cheap, the process is simple, and easy to operate, which is suitable for the treatment of heavy metal wastewater in industries such as electroplating, batteries, and printing;

(4) The heavy metal collector prepared by the present invention can complex reaction with most heavy metal ions, flocculate and precipitate, for heavy metals such as Cu ²⁺ , Ni ²⁺ , Cd ²⁺ , Hg ²⁺ , Pb ²⁺ , Cr ³⁺ The removal rate of ions can reach more than 95%, and the treatment effect is remarkable.

Detailed ways

Below in conjunction with embodiment, the present invention is described in detail.

Example 1

Synthesis of the macromolecular skeleton of the heavy metal scavenger: Dissolve a total of 1 mol of ethylenediamine (0.9 mol) and triethylenetetramine (0.1 mol) in 100 mL of water to prepare a small molecule amine-water solution. Slowly add 1.071mol epichlorohydrin dropwise to the small molecule amine-water solution, and finish adding within 3 hours, then react at 40°C for 3 hours, and stand overnight without stirring or heating. Pour the above overnight solution into a four-necked flask, and while stirring, continue to dropwise add 0.129mol of epichlorohydrin, and at the same time add dropwise 72mL of sodium hydroxide solution (50%, 0.895mol), epichlorohydrin for 6 hours After the internal addition was completed, the sodium hydroxide was added within 2 hours, and the reaction was continued to stir at 70°C for 0.5 hour, and stirred overnight without heating to obtain the product. Add sodium hydroxide solution (50%, 0.305mol) to the above reaction product, mix and stir at room temperature to prepare a 30% aqueous solution to obtain a macromolecular skeleton solution, which is a viscous and transparent yellow liquid.

Grafting of dithiocarbamic acid groups: Weigh 62.88g of the macromolecular skeleton solution into a three-necked flask, add 10g of sodium hydroxide solution (50%, 0.125mol), and then add 0.125mol of carbon disulfide under ice-bath conditions for 15 minutes After the internal dropwise addition was completed, the reaction was carried out in an ice bath for 1 hour to prevent the volatilization of carbon disulfide, and then the temperature was raised to room temperature for 30 minutes to obtain a transparent orange-red product.

Example 2

The parameters for the synthesis of the macromolecular skeleton of the heavy metal scavenger are shown in Table 1, and the synthesis process of the grafted dithiocarbamate group is the same as in Example 1.

Example 3

The parameters for the synthesis of the macromolecular skeleton of the heavy metal scavenger are shown in Table 1, and the synthesis process of the grafted dithiocarbamate group is the same as in Example 1.

Example 4

The parameters for the synthesis of the macromolecular skeleton of the heavy metal scavenger are shown in Table 1, and the synthesis process of the grafted dithiocarbamate group is the same as in Example 1.

Example 5

The parameters for the synthesis of the macromolecular skeleton of the heavy metal scavenger are shown in Table 1, and the synthesis process of the grafted dithiocarbamate group is the same as in Example 1.

Example 6

The parameters for the synthesis of the macromolecular skeleton of the heavy metal scavenger are shown in Table 1, and the synthesis process of the grafted dithiocarbamate group is the same as in Example 1.

Table 1

parameter Example 2 Example 3 Example 4 Example 5 Example 6 n (ethylenediamine): n (triethylenetetramine) 8:2 7:3 6:4 5:5 9:1 The first cross-linking reaction temperature/℃ 40 45 50 40 50 Second cross-linking reaction temperature/°C 70 75 80 85 90 n (total epichlorohydrin): n (total amines) 1.1 1.15 1.2 1.25 1.3 The amount of epichlorohydrin added for the first time 1.071mol 1.071mol 1.071mol 1.071mol 1.071mol The amount of epichlorohydrin added for the second time 0.029mol 0.079mol 0.129mol 0.179mol 0.229mol The amount of sodium hydroxide added for the first time 0.895mol 0.895mol 0.895mol 0.895mol 0.895mol The amount of sodium hydroxide added for the second time 0.205mol 0.255mol 0.305mol 0.355mol 0.405mol

Example 7

The copper-based electroplating wastewater from a plastic electroplating factory in Wuxi was selected, and the measured copper ion concentration was 123.14mg/L, and the pH was 4.8. Add 50 mg/L of the heavy metal trapping agent of Example 1 to Example 6, stir and react for 1 min at 30 r/min, then let it stand and filter, and take the supernatant to measure the concentration of copper ions by atomic absorption spectrometry. The corresponding removal rates are 99.52%, 99.36%, 99.64%, 99.86%, 99.86%, 99.77%.

Example 8

The copper-based electroplating wastewater from a plastic electroplating factory in Wuxi was selected, and the measured copper ion concentration was 123.14mg/L, and the pH was 4.8. Add 60 mg/L of the heavy metal trapping agent of Example 1 to Example 6, stir and react for 1 min at 30 r/min, then let it stand and filter, and take the supernatant to measure the concentration of copper ions by atomic absorption spectrometry. The corresponding removal rates are 99.73%, 99.86%, 99.94%, 99.96%, 99.89%, 99.97%.

Example 9

The chromium-based electroplating wastewater from a plastic electroplating factory in Wuxi was selected, containing Cr ³⁺ ion concentration of 10.335 mg/L and pH of 2.5. Add 70 mg/L of the heavy metal trapping agent of Example 1 to Example 6, at 30 r/min, stir and react for 1 min and then filter it, take the supernatant and measure the concentration of chromium ions by atomic absorption spectrometry. The corresponding removal rates are 96.81%, 95.85%, 95.56%, 95.82%, 96.99%, 95.69%.

Example 10

The chromium-based electroplating wastewater from a plastic electroplating factory in Wuxi was selected, containing Cr ³⁺ ion concentration of 10.335 mg/L and pH of 2.5. Add 80 mg/L of the heavy metal trapping agent of Example 1 to Example 6, stir and react for 1 min at 30 r/min, then let it stand and filter, and take the supernatant to measure the concentration of chromium ions by atomic absorption spectrometry. The corresponding removal rates are 97.82%, 96.65%, 97.64%, 96.28%, 97.99%, 96.62%.

Example 11

The nickel-based electroplating wastewater from a plastic electroplating factory in Wuxi was selected, and the measured Ni ²⁺ ion concentration was 7.88mg/L. Add the heavy metal trapping agent of embodiment 1～embodiment 6 of 50mg/L, under 30r/min, leave standstill to filter after stirring reaction 1min, get supernatant and measure the concentration of its nickel ion with atomic absorption spectrometry, obtain corresponding The removal rate was 95.23%, 95.67%, 97.22%, 97.89%, 98.76%, 97.26%.

Example 12

The nickel-based electroplating wastewater from a plastic electroplating factory in Wuxi was selected, and the measured Ni ²⁺ ion concentration was 7.88mg/L. Add the heavy metal trapping agent of embodiment 1～embodiment 6 of 70mg/L, under 30r/min, leave standstill to filter after stirring reaction 1min, get supernatant and measure the concentration of its nickel ion with atomic absorption spectrometry, obtain corresponding The removal rate was 97.82%, 97.33%, 98.12%, 98.80%, 99.26%, 99.63%.

The patent of the present invention has the same trapping performance to other heavy metal ions.

Claims (3)

1. A preparation method of a water-soluble macromolecular heavy metal trapping agent is characterized in that two kinds of small molecular amines ethylenediamine and triethylenetetramine are cross-linked to generate a macromolecular skeleton, and then graft two Thiocarbamate group generates a macromolecular water-soluble heavy metal trapping agent; comprising the following steps: (1) Synthesis of the macromolecular skeleton of the heavy metal scavenger: Dissolve a total of 1 mol of ethylenediamine and triethylenetetramine in 100mL of water, wherein the molar ratio of ethylenediamine: triethylenetetramine is 9-5: 1- 5. Prepare a small molecule amine-water solution; slowly add 1.071mol of epichlorohydrin dropwise into the small molecule amine-water solution, and finish adding within 3 hours, then react at 40°C to 50°C for 3 hours, and let it stand overnight. No stirring and no heating during this period; pour the above overnight solution into a four-necked flask, and continue to drop epichlorohydrin while stirring, and at the same time add dropwise an alkali solution with a concentration of 50%, 0.895mol, epichlorohydrin 6 The addition is completed within 1 hour, and the alkali solution is added within 2 hours. The total amount of epichlorohydrin added: the total molar ratio of small molecular amines is 1.3 to 1.1: 1, and the reaction is stirred at 70 to 90 ° C for 0.5 hours, and then Stir overnight under the condition of no heating to obtain the product; add 50% alkali solution to the above reaction product, mix and stir at room temperature to prepare a 30% aqueous solution to obtain a macromolecular skeleton solution, which is a viscous and transparent yellow liquid; The total amount of alkali solution added: The total molar ratio of epichlorohydrin is 1: 1; (2) Graft dithiocarbamic acid groups on the macromolecular skeleton: Weigh a certain amount of macromolecular skeleton solution into a three-necked flask, add 50% alkali solution, macromolecular skeleton solution: The mass ratio of alkali solution is 1: 1. Add carbon disulfide in an equimolar amount to the alkaline solution in an ice bath, drop it within 15 minutes, then react in an ice bath for 1 hour to prevent carbon disulfide volatilization, and then warm up to room temperature for 30 minutes. 2. preparation method according to claim 1 is characterized in that, the alkali used in the reaction process is the one in potassium hydroxide and sodium hydroxide. 3. the application of the water-soluble macromolecular heavy metal scavenger prepared by the method of claim 1 is characterized in that it is used for the chelation removal of heavy metal ions in plastic electroplating wastewater, and the addition of this macromolecular heavy metal scavenger is 50～80mg /L.