CN113617330B

CN113617330B - Low-cost and fast Pb adsorption device 2+ Preparation method of Na-SUZ-4 molecular sieve

Info

Publication number: CN113617330B
Application number: CN202111098958.5A
Authority: CN
Inventors: 高珊; 高英; 刘颖慧
Original assignee: Taiyuan University of Technology
Current assignee: Taiyuan University of Technology
Priority date: 2021-09-18
Filing date: 2021-09-18
Publication date: 2023-04-11
Anticipated expiration: 2041-09-18
Also published as: CN113617330A

Abstract

The invention aims to provide a method for selectively treating heavy metal Pb in wastewater with low preparation cost ²⁺ The invention discloses a preparation method of a Na-SUZ-4 molecular sieve capable of being quickly and efficiently removed, belonging to the technical field of wastewater treatment ⁺ The dosage of the organic template in the system is only 3 percent of the original addition amount, and the 100 percent of the K-SUZ-4 molecular sieve can be obtained. Then the Na-SUZ-4 molecular sieve is obtained by ion exchange and is used for Pb in wastewater ²⁺ And (4) removing by adsorption. The Na-SUZ-4 molecular sieve adsorbing material is used for adsorbing Pb ²⁺ Has obvious specific adsorption, fast balance speed and high adsorption capacity, and can be circularly adsorbed for 5 times without obvious reduction of the removal rate. The use amount of the organic template agent is greatly reduced, so that the preparation cost of the molecular sieve is low, and the preparation process is environment-friendly.

Description

Low-cost and fast Pb adsorption device 2+ Preparation method of Na-SUZ-4 molecular sieve

Technical Field

The invention belongs to the technical field of wastewater treatment, and particularly relates to a low-cost and rapid Pb adsorption device ²⁺ A preparation method of the Na-SUZ-4 molecular sieve.

Background

Water is an essential element on which humans rely for survival. With the rapid development of the current industry and the continuous acceleration of the urbanization process, the problem of heavy metal pollution in water bodies becomes more serious, wherein the discharge amount of heavy metal lead (Pb) accounts for more than 35 percent of the total discharge amount of all heavy metals. Pb is a heavy metal element which seriously harms human health, can affect the nervous system, the hematopoietic system, the urinary system, the reproductive system and the like of a human body, and particularly can affect the growth and the intelligence development of children. Lead pollution events are frequent due to illegal discharge of lead-containing wastewater by lead ore mining and smelting enterprises, storage battery manufacturing enterprises and the like, so that the blood lead of children and even adults exceeds the standard and is poisoned. Therefore, the method is an irreparable task in the environmental field, and can economically, effectively, safely and environmentally remove lead in the wastewater and reduce the accumulation and harm of the lead in the environment. Among the methods for treating Pb (II) in wastewater, the adsorption method is one of effective means due to the advantages of low energy consumption, high efficiency, convenient operation, no secondary pollution and the like. Commonly used adsorbents include activated carbons, minerals, high molecular organics, zeolites, biomass, and the like. The existing adsorbing materials generally have the problems of low adsorption rate, low adsorption quantity, poor selectivity and the like. Patent CN 111229181A reports an organic material for efficiently and quickly adsorbing heavy metal Pb (II), however, the preparation method of the material is complex and the cost is high. Therefore, the research and development of the low-cost, specific, rapid and efficient adsorbent is a key factor for the practicability of the adsorption method.

K-SUZ-4 is a microporous silicon-aluminum molecular sieve with an SZR structure, and can effectively remove heavy metal cations in water through the actions of electrostatic attraction, ion exchange and the like. In the earlier report of this group (Journal of Cleaner Production 312 (2021) 127825), K-SUZ-4 was synthesized from industrial waste slag, i.e., silica fume and aluminum fume, and it was found that the maximum adsorption amount of Cd (II) in water by the molecular sieve under neutral conditions (pH = 7) could reach 256.3 mg/g. However, the use of a large amount of organic templates in the above K-SUZ-4 synthesis method not only increases the preparation cost of the molecular sieve, but also causes pollution to the environment and harms human health. In addition, the time required for the adsorption reaction to reach equilibrium is as long as 2 hours.

Disclosure of Invention

The invention aims to provide a method for selectively treating heavy metal Pb in wastewater with low preparation cost ²⁺ The invention discloses a preparation method of a Na-SUZ-4 molecular sieve capable of being rapidly and efficiently removed, which adds inorganic substance K into an SUZ-4 synthesis system ⁺ The usage amount of the organic template agent tetraethyl ammonium hydroxide is reduced to 3 percent of the original addition amount, the synthesis cost of the molecular sieve is greatly reduced, and the Na-SUZ-4 molecular sieve is utilized to realize the heavy metal Pb in the wastewater ²⁺ The adsorption and removal are carried out specifically, quickly and efficiently.

The invention adopts the following technical scheme:

low-cost and fast Pb adsorption device ²⁺ The preparation method of the Na-SUZ-4 molecular sieve comprises the following steps:

step one, preparing a K-SUZ-4 molecular sieve: mixing silica fume, aluminum fume, tetraethyl ammonium hydroxide, potassium hydroxide and deionized water in proportion to obtain a mixture, adding potassium salt into the mixture to obtain a gel mixture, putting the formed gel mixture into a reaction kettle, dynamically crystallizing at the rotating speed of 20 rpm for 4.5 to 5 days at the temperature of 150 ℃, and after crystallization is finished, separating, drying and calcining the obtained product to obtain the K-SUZ-4 molecular sieve;

step two, preparing the Na-SUZ-4 molecular sieve: placing the obtained K-SUZ-4 molecular sieve in 10 mL of Na with the concentration of 0.1 to 2mol/L ⁺ Ion exchange is carried out in the solution at the temperature of 30 to 150 ℃ for 2 to 24 hours, after the exchange is finished, the product is separated and dried, and the Na-SUZ-4 molecular sieve is obtained;

in the third step, heavy metals Pb ²⁺ Adsorption of (2): adding 0.003 to 0.04g of Na-SUZ-4 molecular sieve into 50 mL of Pb at a concentration of 10 to 70 mg/L ²⁺ Adjusting the pH value of the solution to 2-8, oscillating the solution in an oscillating bed for 0-30 min, sampling the solution at intervals, and detecting Pb in the solution by a flame atomic absorption spectrometer ²⁺ And calculating the adsorption capacity according to the mass of the adsorbent and the concentrations of the heavy metal ions before and after adsorption.

Further, in the first step, the silica fume, the aluminum fume, the tetraethyl ammonium hydroxide, the potassium hydroxide and the deionized water are SiO ₂ :Al ₂ O ₃ :TEAOH:KOH:H ₂ O = 21.2.

Further, the potassium salt is represented by K in the first step ⁺ TEAOH =20 to 40 in a molar ratio range.

Further, in the first step, the potassium salt comprises any one or a combination of potassium chloride, potassium sulfate and potassium nitrate.

Further, in the second step, the sodium ion solution comprises any one or a mixture of sodium chloride, sodium carbonate, sodium bicarbonate and sodium hydroxide.

The invention has the following beneficial effects:

1. the invention provides a synthetic bodyAdding K to ⁺ The use of organic template agent is greatly reduced, the synthesis cost of the SUZ-4 molecular sieve is reduced, and the increment of tetraethyl ammonium hydroxide is 3 percent of the addition of the normal synthesis method.

2. The method adopts the Na-SUZ-4 molecular sieve with low cost to adsorb the heavy metal lead ions in the wastewater, has obvious specificity, large adsorption capacity and high adsorption rate, and can achieve adsorption balance within 5 min.

3. The Na-SUZ-4 molecular sieve prepared by the invention is subjected to desorption-re-adsorption circulation for 5 times, and the adsorption quantity is basically kept unchanged.

4. The Na-SUZ-4 molecular sieve prepared by the invention adsorbs and removes Pb in water ²⁺ Can resist Zn ²⁺ 、Cu ²⁺ 、Ni ²⁺ 、Mn ² ⁺ Interference of heavy metal ions.

Drawings

FIG. 1 is a graph showing the adsorption reaction kinetics of the Na-SUZ-4 molecular sieve prepared by the present invention.

FIG. 2 is a graph showing the relationship between the amount of Na-SUZ-4 molecular sieve prepared by the present invention and the adsorption amount and adsorption rate.

FIG. 3 shows Pb ²⁺ Initial concentration of the solution is plotted against the amount of adsorption.

FIG. 4 shows Pb ²⁺ The pH value of the solution is plotted against the adsorption amount.

FIG. 5 shows the Na-SUZ-4 molecular sieve pair Pb ²⁺ Selectivity of (2).

FIG. 6 is a diagram showing the recycling of the Na-SUZ-4 molecular sieve prepared by the present invention.

Detailed Description

step two, preparing the Na-SUZ-4 molecular sieve: placing the obtained K-SUZ-4 molecular sieve in 10 mL of Na with the mol/L ratio of 0.1 to 2mol/L ⁺ Ion exchange is carried out in the solution at the temperature of 30 to 150 ℃ for 2 to 24 hours, after the exchange is finished, the product is separated and dried, and the Na-SUZ-4 molecular sieve is obtained;

1. Effect of preparation conditions of Na-SUZ-4 molecular sieves on adsorption Properties

Example 1

1) 0.32 g of aluminum ash, 1.92 g of potassium hydroxide and 10 g of deionized water were mixed, and after stirring for 30 minutes, a mixed solution containing 4.60 g of silica ash, 0.2 g of 25% tetraethylammonium hydroxide aqueous solution and 23 g of deionized water was added thereto.

Initial gel molar ratio of SiO ₂ :Al ₂ O ₃ :TEAOH:KOH:H ₂ O = 21.2. After stirring was continued for 30 min, the resulting mixture was transferred to a 50 mL hydrothermal kettle and dynamically crystallized at 150 ℃ for 4.5 days at 20 rpm. And after the reaction is finished, separating, washing and drying the solid phase from the liquid phase, and calcining to obtain the K-SUZ-4 molecular sieve solid particles.

2) 0.2 g of the K-SUZ-4 molecular sieve obtained above was placed in 10 mL of Na solution at 0.5mol/L ₂ CO ₃ In the solution, ion exchange was carried out at 30 ℃ for 2h. And after the exchange is finished, separating and drying the product to obtain the Na-SUZ-4 molecular sieve.

3) 0.01 g of Na-SUZ-4 molecular sieve was added to 50 mL of 50 mg/L Pb ²⁺ In solution, shake for 5 min on a shaking bed. Detection of Pb in solution by flame atomic absorption spectrometer ²⁺ And (4) concentration. Measuring Pb at equilibrium ²⁺ The adsorption capacity of (A) was 168.4 mg/g.

Example 2

Example 1 was repeated, but 1 g of potassium chloride in the step 1) was changed to 0.68 g of potassium nitrate, and the resulting mixture was dynamically crystallized at 150 ℃ for 5 days; placing the K-SUZ-4 molecular sieve in the step 2) in 10 mL of 0.1 mol/L NaCl solution, and carrying out ion exchange at 150 ℃ for 24 h. Measured Pb in Water ²⁺ The adsorption capacity was 175.5 mg/g.

Example 3

Example 1 was repeated except that 1 g of potassium chloride in step 1) was changed to a mixture of 0.58 g of potassium sulfate and 0.68 g of potassium nitrate, and the K-SUZ-4 molecular sieve in step 2) was placed in 10 mL of a 2mol/L NaOH solution and ion-exchanged at 60 ℃ for 8 hours. After equilibration, pb in the measured water ²⁺ The adsorption capacity was 148.4 mg/g.

Example 4

Example 2 was repeated except that the K-SUZ-4 molecular sieve in step 2) was placed in 10 mL of 0.5mol/L Na ₂ CO ₃ And NaHCO ₃ Mixing the solution. After equilibration, pb in the measured water ²⁺ The adsorption capacity was 158.5 mg/g.

2. Effect of adsorption conditions on adsorption Performance

Example 5

Example 1 was repeated, but the oscillation in step 3) was changed from 5 min to 30 min, with samples taken at intervals. The kinetic curve of the adsorption reaction is shown in FIG. 1. As can be seen from FIG. 1, the adsorption reaction has a faster rate, and the adsorption equilibrium can be reached within 5 min.

Example 6

Example 1 was repeated, but the amount of the Na-SUZ-4 molecular sieve added in step 3) was changed to 0.003 to 0.04 g. The relationship between the amount of adsorbent added and the amount and rate of adsorption is shown in FIG. 2.

Example 7

Example 1 was repeated, but for Pb in step 3) ²⁺ The concentration of the solution is 10 to 70 mg/L. The relationship between the initial concentration of the heavy metal solution and the amount of adsorption is shown in FIG. 3.

Example 8

Example 1 was repeated, but in step 3) the pH of the solution was adjusted to 2, 3, 4, 5, 6, 7, 8. The relationship between the pH value of the solution and the amount of adsorption is shown in FIG. 4.

3. Other heavy metal ion in the solution to Pb ²⁺ Influence of adsorption

Example 9

Example 1 was repeated except that 0.01 g of Na-SUZ-4 molecular sieve was added to 50 mL of 50 mg/L Zn in step 3) ²⁺ \Pb ²⁺ 、Cu ²⁺ \Pb ²⁺ 、Ni ²⁺ \Pb ²⁺ 、Mn ²⁺ \Pb ²⁺ In the binary mixed solution of (1). The results are shown in FIG. 5. As can be seen from FIG. 5, the Na-SUZ-4 molecular sieve is responsible for Pb ²⁺ Has good specificity, and the existence of other heavy metal cations is opposite to Pb ²⁺ The influence of adsorption is small.

4. Recycling of Na-SUZ-4 molecular sieve adsorbent

Example 10

Example 1 was repeated. Will adsorb Pb ²⁺ Drying the Na-SUZ-4 molecular sieve at 110 ℃ for 6.0 h, weighing 0.01 g of the Na-SUZ-4 molecular sieve into an EDTA (ethylene diamine tetraacetic acid) analytic solution containing 1 mol/L, oscillating at 30 ℃ for 480 min, filtering and washing. The residue (Na-SUZ-4 molecular sieve) was dried at 110 ℃ for 6.0 hours, and then step 3 in example 1 was repeated. The desorption-re-adsorption process was repeated 5 times, and the results are shown in FIG. 6. As can be seen from the figure, after 5 times of repetition, the adsorption capacity of the adsorbent is not obviously reduced, which indicates that the Na-SUZ-4 molecular sieve adsorbent has better recycling performance.

Comparative example 1

Example 1 was repeated. But without addition of K ⁺ And the increase of the organic templating agent TEAOH was 5.67g. After adsorption equilibrium, pb in the measured water ²⁺ The adsorption capacity was 147.6 mg/g.

Comparative example 2

1) Repeat step 1) of example 1.

0.01 g of K-SUZ-4 molecular sieve was added to 50 mL of 50 mg/L Pb ²⁺ In the solution, the solution was shaken for 5 min on a shaking bed. Detection of Pb in solution by flame atomic absorption spectrometer ²⁺ And (4) concentration. Measuring Pb at equilibrium ²⁺ The adsorption capacity of (2) is 135.6 mg/g, which is lower than that of the Na-SUZ-4 molecular sieve.

Claims

1. Low-cost and fast Pb adsorption device ²⁺ The preparation method of the Na-SUZ-4 molecular sieve is characterized by comprising the following steps: the method comprises the following steps:

step two, preparing the Na-SUZ-4 molecular sieve: placing the obtained K-SUZ-4 molecular sieve in 10 mL of Na with the concentration of 0.1 to 2mol/L ⁺ In the solution, ion exchange is carried out for 2 to 24 hours at the temperature of 30 to 150 ℃, after the exchange is finished, the product is separated and dried, and the Na-SUZ-4 molecular sieve is obtained;

in the first step, the silica fume, the aluminum fume, the tetraethyl ammonium hydroxide, the potassium hydroxide and the deionized water are mixed according to SiO ₂ :Al ₂ O ₃ :TEAOH:KOH:H ₂ O = 21.2;

in the first step the potassium salt is as defined by K ⁺ TEAOH =20 to 40 in a molar ratio range;

in the first step, the potassium salt comprises any one or a combination of potassium chloride, potassium sulfate and potassium nitrate.

2. The method of claim 1 for low cost and fast adsorption of Pb ²⁺ The preparation method of the Na-SUZ-4 molecular sieve is characterized by comprising the following steps: in the second step, the sodium ion solution comprises any one or a mixture of sodium chloride, sodium carbonate, sodium bicarbonate and sodium hydroxide.

3. Application of Na-SUZ-4 molecular sieve prepared by using preparation method of claim 1 in heavy metal Pb ²⁺ The adsorption of (2), characterized in that: the method comprises the following steps: adding 0.003 to 0.04g of Na-SUZ-4 molecular sieve into 50 mL of Pb at a concentration of 10 to 70 mg/L ²⁺ Adjusting the pH value of the solution to 2-8, and oscillating the solution in an oscillating bed for 0-30min, sampling at intervals, and detecting Pb in the solution by flame atomic absorption spectrometry ²⁺ And calculating the adsorption capacity according to the mass of the adsorbent and the concentrations of the heavy metal ions before and after adsorption.