CN103724619B - A kind of poly m-phenylene diamine and synthesis and methods for using them thereof - Google Patents

Abstract

The invention discloses a poly-m-phenylenediamine and its synthesis and application method. Using m-phenylenediamine as a raw material, adding an oxidizing agent to an alcohol solvent and adding a certain amount of diethanolamine solution at the same time, the synthesis of poly-m-phenylenediamine can be realized. Morphology control, the yield can reach 87.5%. The obtained poly-m-phenylenediamine product has a maximum adsorption capacity of 2318.5 mg·g ^-1 for silver ions in water, and has good selective adsorption; and for low-concentration silver-containing water, the concentration of silver ions after treatment is much lower than that of WHO The prescribed safe value of silver to the human body is 0.05ppm.

Description

A kind of polym-phenylenediamine and its synthesis and application method

technical field

The invention belongs to the technical field of material preparation for treating silver-containing wastewater, and in particular relates to a poly-m-phenylenediamine adsorption material with high efficiency and high selective adsorption performance for silver ions and a synthesis and application method thereof.

Background technique

Silver is an important precious metal, which is widely used in decoration, electroplating, photosensitive materials, chemical industry, electronics, scientific research and other fields. Compared with other industries, the amount of silver-containing wastewater is not very large, but the direct discharge of silver-containing wastewater into the environment will not only pollute the environment, but also cause a waste of silver resources. Therefore, it is of great significance to recover the silver in the waste liquid.

At present, the methods for recovering silver from silver-containing waste liquid mainly include precipitation method, reduction substitution method, electrolysis method and ion exchange method. Insufficient silver ion concentration waste liquid. The adsorption method has attracted people's attention due to its simple operation and low cost. For example, the use of modified activated carbon can efficiently adsorb trace silver ions in water, but the saturated adsorption capacity reported in the literature can only reach about 75 mg/g at present, which is not applicable to Application of industrial wastewater (Liu Wenhong et al. Precious Metals, 2004, 1:1~6). The R&D and application of synthetic adsorption materials such as activated carbon fiber, chelating resin and poly(1,8-naphthalene diamine) have made great progress in the adsorption treatment of silver-containing wastewater, among which poly(1,8-naphthalene diamine) silver The ion adsorption capacity reaches 1920mg/g, which is the highest value reported in the current literature (Huang Meirong et al. Industrial Water and Wastewater, 2005, 1:9-12; LiX.G., etc.. Actamaterialia, 2004, 52:5363-5374) . However, the high cost of these synthetic materials limits their industrial applications. In recent years, considering the cost problem, attention has been paid to the preparation of poly-m-phenylenediamine adsorption materials. Its adsorption capacity for silver ions in water ranges from several hundred to 1886.6 mg/g (201110088356.1), showing good adsorption performance, but poly-m-phenylene diamine The synthesis yield of diamine is still on the low side, and its adsorption performance needs to be further improved.

Contents of the invention

The purpose of the present invention is to provide a kind of polym-phenylenediamine adsorption material with high efficiency and high selective adsorption capacity for silver ions and its synthesis and application method based on the deficiencies of existing adsorption materials, which can further greatly increase the The yield of amine is beneficial to reduce production cost and improve resource utilization; more importantly, it can greatly improve the adsorption performance of the synthetic product on metal silver ions in water, and show good selective adsorption.

The purpose of the present invention is achieved in the following ways.

A method for synthesizing poly-m-phenylenediamine comprises the steps of dissolving m-phenylenediamine in alcohol, adding an oxidizing agent and diethanolamine solution in a stirring state to react, filtering and washing to obtain a poly-m-phenylenediamine product.

The alcohol includes one or both of methanol and ethanol. The weight percent of the m-phenylenediamine in the alcohol solution is 2-15%. The molar ratio of diethanolamine to m-phenylenediamine is 0.3-1.5:1.

The oxidizing agent is persulfate, and the molar ratio of m-phenylenediamine to oxidizing agent is 1:1-2.

The reaction time of the above method is 2-8 hours, and the reaction is carried out at 15-35°C.

A kind of poly-m-phenylenediamine is the poly-m-phenylenediamine synthesized by the above-mentioned method.

The above-mentioned polym-phenylenediamine is used for adsorbing metal silver ions in the water body.

Beneficial effects of the present invention:

(1) The synthesis yield of poly-m-phenylenediamine has been greatly improved to 87.5%, which is much higher than the synthesis yield reported in the current literature (generally between 40-70%); and the morphology control of the synthesized product has been realized, and the product ratio has been improved. The surface area reduces the cost of industrial application and reduces the risk of secondary pollution in the synthesis process.

(2) The adsorption performance of the synthesized poly-m-phenylenediamine adsorption material was improved. The maximum adsorption capacity of the synthesized product to silver ions in water reaches 2318.5 mg·g ^-1 , far superior to the existing reported adsorbents. Moreover, it can deeply treat low-concentration silver-containing water, and the concentration of silver ions after treatment is far lower than the safe value of 0.05ppm of silver for human body stipulated by WHO.

(3) The synthesized poly-m-phenylenediamine exhibited good selective adsorption for silver ions.

The above effects show that the adsorption material provided by the invention has good industrial application adaptability.

Description of drawings

Fig. 1 is the scanning electron microscope and the transmission electron microscope figure of the polym-phenylenediamine prepared by embodiment 1-3 and comparative example 1;

A, B are comparative example 1; C, D are embodiment 1; E, F are embodiment 2; G, H are embodiment 3;

Fig. 2 is the infrared spectrogram of the polym-phenylenediamine prepared by embodiment 1-3 and comparative example 1;

a is comparative example 1; b is embodiment 1; c is embodiment 2; d is embodiment 3;

Fig. 3 is the transmission electron microscope figure after embodiment 2 adsorbs silver ions;

Fig. 4 is the X-ray diffraction figure of embodiment 2 after absorbing silver ions.

detailed description

The present invention will be further described below in conjunction with the examples, without limiting the present invention.

Example 1

Weigh 3.0g (0.0277mol) of m-phenylenediamine and dissolve it in 100mL of methanol, stir in a constant temperature water bath at 30°C for 15min, and mix the monomer solution evenly. Weigh 6.6g (0.0277mol) of sodium persulfate and dissolve it in 20mL of distilled water. The above-mentioned sodium persulfate solution and 20 mL of methanol solution with a concentration of 0.5 mol/L diethanolamine were simultaneously added dropwise to the reaction system at a rate of 2 mL/min, and the addition was completed in about 10 minutes. Then, the stirring reaction was continued for 3h. After the reaction, filter, and then wash the product with distilled water, 1:1 (volume ratio) ammonia water, absolute ethanol, and distilled water until it is colorless, and dry it in an oven at 60°C for 12 hours to constant weight to obtain black poly-m-phenylenediamine powder.

Embodiment 2～3

The concentrations of the added diethanolamine were adjusted to 1 and 1.5 mol·L ^-1 , respectively, and other conditions were the same as in Example 1 to prepare poly-m-phenylenediamine.

Comparative Example 1

According to the method of Example 1, no diethanolamine was added during the reaction to prepare poly-m-phenylenediamine.

The polymers prepared in Examples 1-3 and Comparative Example 1 were tested using Nicolet IS10 Fourier transform infrared spectroscopy, and the obtained spectrograms are shown in FIG. 2 . Among the figures a is the spectrogram of the product prepared in Comparative Example 1, and b-d in the figure are the spectrograms prepared in Examples 1-3 respectively.

According to Fig. 2, the broad absorption peak near 3400～3100cm ^-1 is caused by the vibration of the secondary amino group (-NH-) group in polym-phenylenediamine. The two absorption peaks around 1620cm ^-1 and 1500cm ^-1 indicate the stretching vibration of the quinone structure and the benzene structure on the polymer molecular chain respectively. Around 1250cm ^-1 is the stretching vibration of CN on the benzene ring. It can be seen from the figure that as the concentration of the added diethanolamine solution increases, the benzene structure absorption peak (1500cm ^-1 ) of the product poly-m-phenylenediamine is slightly enhanced. It shows that the obtained product is poly-m-phenylenediamine.

Example 4

Under the condition of a constant temperature water bath at 30°C, 20 mL of silver nitrate solution with an initial concentration of 62 mmol·L ^-1 was adsorbed with 25 mg of the polymers prepared in Examples 1-3 and Comparative Example 1 respectively, and the reaction lasted for 72 hours. The reacted solution was filtered, and the concentration of silver ions in the filtrate was determined by Volhard titration. The polymers prepared by each embodiment are shown in Table 1 for the adsorption capacity of silver ions. It can be seen from the table that the product prepared by adding diethanolamine has better adsorption performance on silver ions than the product prepared without adding diethanolamine. It should be pointed out that an appropriate concentration of diethanolamine can maximize the product's adsorption performance on silver ions, and the concentration of diethanolamine is too high or too low to reduce its adsorption capacity. This may be closely related to the morphology of the product. As shown in Figure 1, when the concentration of diethanolamine is low (such as 0.5 and 1mol L ^-1 ), the product is a one-dimensional nano-hollow shape, and its silver ion adsorption performance is greatly improved. , as high as 1685 mg·g ^-1 , which is 477 mg·g ^-1 higher than that of the product without adding diethanolamine. However, when the concentration of diethanolamine continued to increase to 1.5mol·L ^-1 , the product tended to form irregular microspheres, and the hollow morphology also became less. Correspondingly, the specific surface area of the product becomes smaller, resulting in a tendency to decrease the adsorption performance. But in general, adding diethanolamine in the polymerization process is beneficial to improve the adsorption performance of the product on silver ions.

The productive rate of each embodiment and comparative example is calculated according to the formula (1), and the data are shown in Table 1. It can be seen that with the increase of the concentration of diethanolamine, the production of poly-m-phenylenediamine increases first and then decreases. When adding diethanolamine at a concentration of 1 mol·L ⁻¹ (Example 2), the yield of poly-m-phenylenediamine reaches the highest 87.5%, which is 13.5% higher than that without adding diethanolamine. Explain that this method is also conducive to improving the productive rate of poly-m-phenylenediamine, and is conducive to industrial production.

$\mathrm{<span\; class="notranslate">\; \&rho;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; D.</span>}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; D.</span>}}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}\mathrm{<span\; class="notranslate">\; \%</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

ρ: polymer yield;

M _PmPD : the weight (g) of polym-phenylenediamine;

M _mPD : weight of m-phenylenediamine (g)

Table 1

sample Comparative Example 1' Example 1 Example 2 Example 3 Concentration of diethanolamine/mol·L ^-1 0 0.5 1 1.5 Adsorption capacity/mg·g ^-1 1208 1382 1685 1564 Yield/% 74.0 80.2 87.5 86.2

Example 5

Under the condition of a constant temperature water bath at 30°C, 25 mg of the poly-m-phenylenediamine product prepared in Example 2 was used to adsorb 20 mL of silver nitrate solution, and the concentrations of the silver ions were 30, 62, 94, 123, 152, and 200 mmol·L ^-1 , and the reaction lasts for 72h. The mixed solution after the reaction was filtered, and the silver ion concentration in the filtrate was determined by Volhard titration.

The adsorption rate and adsorption amount of the poly-m-phenylenediamine product prepared in this example to silver ions are shown in Table 2. It can be seen that the adsorption amount of the polymerized product to adsorb silver ions increases with the increase of the concentration of silver ions. When the concentration of silver ions increased to 200mmol·L ^-1 , the adsorption capacity of the polymer to silver ions was as high as 2318.5 mg·g ^-1 , much higher than the adsorbents reported in the literature. It can be seen from Figures 3 and 4 that a large amount of adsorbed silver ions are reduced to simple silver. It shows that poly-m-phenylenediamine reduces a large amount of silver ions to simple silver in the adsorption process, which is beneficial to the recovery of silver.

Under the condition of constant temperature water bath at 30°C, the poly-m-phenylenediamine prepared according to 201110088356.1 adsorbed 20mL silver nitrate solution, the concentration of silver ions was 200mmol·L ^-1 , the reaction continued for 72h, and the adsorption capacity of the product increased to 1920mg/g, but still Far lower than the performance of the polym-phenylenediamine product prepared in Example 2 of the present invention.

Table 2

Initial concentration of silver ions/mol·L ^-1 30 62 94 123 152 200 Adsorption capacity/mg·g ^-1 1086.0 1685.3 1899.6 1944 2011.6 2318.5

Low concentration silver ion removal effect. Under the condition of a constant temperature water bath at 30°C, 25 mg of the poly-m-phenylenediamine product prepared in Example 2 was used to adsorb 20 mL of a 0.25 ^{mmol·L -1} silver nitrate solution for adsorption reaction, and the reaction lasted for 72 hours. The mixed solution after the reaction is filtered, and the concentration of silver ions in the filtrate is determined by atomic absorption method. The results show that the removal rate of silver ions reaches 99.94%, and the concentration of residual silver ions in the water body is far lower than the safe value of 0.05ppm for silver to the human body stipulated by WHO, which shows that the adsorption material prepared by the present invention can deeply treat low-concentration silver-containing water bodies.

Example 6

Under the condition of a constant temperature water bath at 30°C, 20 mL of the mixed solution of heavy metal ions was adsorbed with 25 mg of the poly-m-phenylenediamine product prepared in Example 2, and the reaction was carried out for 72 hours. The mixed solution contains 10mmol·L ^-1 Ag ⁺ , 10mmol·L ^-1 Cu ²⁺ , 10mmol·L ^-1 Pb ²⁺ and 10mmol·L ^-1 Zn ²⁺ respectively. After the reaction, the solution is filtered, the silver ion concentration in the filtrate is determined by Volhard titration, and the concentrations of Cu ²⁺ , Pb ²⁺ and Zn ²⁺ are determined by atomic absorption method. The adsorption results are shown in Table 3. It can be seen that the polym-phenylenediamine hollow nanoparticles exhibit good adsorption performance on Ag ⁺ , even in the presence of Cu ²⁺ , Pb ²⁺ and Zn ²⁺ at the same time, its adsorption on Ag ⁺ The efficiency decreased slightly but still reached 59.8%, while the adsorption performance for Cu ²⁺ , Pb ²⁺ and Zn ²⁺ was obviously poor (<6%). This shows that the product synthesized by this method has good selective adsorption performance for silver ions, which is beneficial to the separation and recovery of silver in complex wastewater.

table 3

Claims (9)

1. a synthetic method of poly-m-phenylenediamine, is characterized in that, m-phenylenediamine is dissolved in alcohol, adds oxidant and diethanolamine solution simultaneously under agitation and reacts, filters, washes and promptly obtains poly-m-phenylenediamine The product, the molar ratio of diethanolamine to m-phenylenediamine is 0.3-1.5:1. 2. The method according to claim 1, wherein the alcohol comprises one or both of methanol and ethanol. 3. The method according to claim 1, characterized in that, the weight percent of the m-phenylenediamine in the alcohol solution is 2-15%. 4. The method according to claim 1, characterized in that, said oxidizing agent is a persulfate. 5. The method according to claim 1, characterized in that the molar ratio of m-phenylenediamine to oxidizing agent is 1:1-2. 6. The method according to claim 1, characterized in that the reaction time is 2 to 8 hours. 7. The method according to claim 1, characterized in that the reaction is carried out at 15-35°C. 8. A poly-m-phenylenediamine, characterized in that, is the poly-m-phenylenediamine synthesized by the method described in any one of claims 1-7. 9. The application method of poly-m-phenylenediamine as claimed in claim 8, characterized in that, it is used to adsorb metal silver ions in the water body.