CN102008939A - Method for preparing aluminum-manganese composite oxide modified molecular sieve - Google Patents

Abstract

The invention discloses a method for preparing an aluminum-manganese composite oxide modified molecular sieve, which comprises the following steps of: preparing the mixed solution of aluminum salt and manganese salt, slowly adding a proper amount of oxidant solution with uniform stirring into the mixed solution of aluminum salt and manganese salt, continuing to perform stirring for a while to ensure full reaction, adding a proper amount of alkali liquor adjusting solution to adjust the pH value of the solution to be 6 to 8, adding a proper amount of molecular sieve into the solution, completely oscillating the solution, standing and aging the solution for a while, taking the molecular sieve out, and washing with water and drying the molecular sieve to obtain the aluminum-manganese composite oxide modified molecular sieve.

Description

A kind of preparation method of aluminum-manganese composite oxide modified molecular sieve

technical field

The invention relates to a preparation method of an aluminum-manganese composite oxide modified molecular sieve adsorbent used for removing arsenic pollutants in water, having a high specific surface area and excellent adsorption performance, and a method for using it in water treatment applications. The invention belongs to the technical field of water treatment application.

Background technique

Arsenic element is ubiquitous in nature and has attracted widespread attention because of its highly toxic and strong carcinogenicity. Inorganic arsenic includes trivalent arsenic As(III) and pentavalent arsenic As(V), and As(III) is far more harmful than As(V), and its toxicity can reach more than 60 times that of the latter. Drinking water containing arsenic for a long time will increase the risk of bladder cancer, lung cancer, kidney cancer and skin cancer. Arsenic in water is a research hotspot at home and abroad.

Compared with other arsenic removal methods such as coagulation method, ion exchange method and membrane treatment, adsorption method has been widely used in water treatment systems with low arsenic concentration because of its advantages of simplicity, economy and renewability. However, currently commonly used adsorbents for arsenic removal, such as activated alumina and activated carbon, usually only have good adsorption capacity for As(V), but poor removal capacity for As(III). The addition of pre-oxidation not only increases the processing cost and operational difficulty, but also may produce by-products that are potentially harmful to human health. On the other hand, according to recent domestic and foreign literature reports, low-cost materials usually have a small adsorption capacity for arsenic, such as iron-loaded sand, natural iron-manganese ore, etc.; while materials with high adsorption capacity are often too expensive, such as titanium dioxide . This also limits the popularization and application of arsenic removal adsorption materials. Therefore, the research and development of new adsorption materials with low cost and excellent removal effect on both As(III) and As(V) is a hot and difficult issue in research and technology development at home and abroad.

Aluminum oxide has good removal ability for As(V), but it is difficult to remove As(III). Manganese dioxide has good oxidation performance for As(III), but low adsorption capacity for As(V).

Molecular sieve is a kind of aluminosilicate compound with cubic lattice. It is mainly composed of silicon and aluminum through oxygen bridges to connect the main city with an empty skeleton structure. . Molecular sieves have the advantages of low fluid resistance, high adsorption speed, large adsorption capacity, strong selectivity, and high mechanical strength, but simple molecular sieves do not have high selectivity for arsenic.

Therefore, how to effectively combine the chemical properties of aluminum oxide and manganese dioxide and use the structural properties of molecular sieves to simultaneously remove As(III)/As(V) has become a subject to be studied. At present, there are no literature reports and patent publications on the research and application of using aluminum-manganese composite oxides to modify molecular sieves to remove arsenic in water.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for preparing an adsorbent for removing arsenic pollutants-aluminum-manganese composite oxide modified molecular sieve, and a method for using the adsorbent in water treatment. In the adsorption material involved in the present invention, the molecular sieve with a porous structure is the supporting matrix, and the aluminum-manganese composite metal oxide is the main part of the adsorption. The adsorption material involved in the invention has excellent adsorption efficiency with broad spectrum for both As(III) and As(V).

Technical scheme of the present invention:

A method for preparing an aluminum-manganese composite oxide-modified molecular sieve, comprising preparing a mixed solution of aluminum salt and manganese salt, slowly adding an appropriate amount of oxidant solution to the mixed solution of aluminum salt and manganese salt under uniform stirring, and continuing to stir for 15min-2h In order to ensure full reaction, add an appropriate amount of lye to adjust the pH value of the solution to 6-8, then add an appropriate amount of molecular sieve into the solution, first fully shake, then stand and age for 2-24 hours, and finally remove the molecular sieve and wash and dry it Prepared.

In the preparation method of the aluminum-manganese composite oxide modified molecular sieve, the aluminum salt solution includes one of aluminum sulfate, aluminum chloride, polyaluminum sulfate, polyaluminum chloride, alum, or a mixture thereof in any ratio; The manganese salt is selected from one of manganese chloride, manganese sulfate, manganese nitrate or any mixture thereof.

In the preparation method of the molecular sieve modified by the aluminum-manganese composite oxide, the molar ratio of the aluminum salt and the manganese salt is 1:1 to 18:1, and the reaction time after adding the oxidant is 15 minutes to 2 hours.

In the preparation method of the aluminum-manganese composite oxide modified molecular sieve, the lye used is one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or a mixture thereof in any ratio.

In the preparation method of the aluminum-manganese composite oxide-modified molecular sieve, the oxidant solution is permanganate, and the molar ratio of the oxidant to the manganese salt is 2:3.

In the preparation method of the aluminum-manganese composite oxide-modified molecular sieve, the oxidant solution is one of hypochlorite, hydrogen peroxide, liquid chlorine, etc., and the molar ratio of the oxidant solution to the manganese salt is 1:1.

In the preparation method of the aluminum-manganese composite oxide modified molecular sieve, the supporting matrix is selected from molecular sieves with a particle size range of 0.2mm-2mm, and the types are 3A, 4A, 5A, 13X and HY. One or any combination of two or more.

In the preparation method of the molecular sieve modified by the aluminum-manganese composite oxide, after the molecular sieve is added to the mixed liquid, the shaking time is 0.5-12 hours, and the temperature of the aging step is room temperature, and the aging time is 2-24 hours.

In the preparation method of the aluminum-manganese composite oxide-modified molecular sieve, the drying step is to dry at 50-75°C for 6-24 hours, and then raise the temperature to 90-180°C for 3-12 hours.

Features of the present invention:

The preparation process of the aluminum-manganese composite oxide modified molecular sieve adsorbent is simple and low in cost.

Al-Mn composite oxide modified molecular sieve adsorbent can show good removal effect on trivalent arsenic As(III) and pentavalent arsenic As(V) and other pollutants.

The prepared aluminum-manganese composite oxide modified molecular sieve adsorbent has fast adsorption speed, large capacity and excellent water purification performance.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments.

Example 1 Preparation of aluminum-manganese composite oxide/molecular sieve adsorbent: Prepare 200ml of a mixed solution of 0.25mol/L aluminum chloride and 0.15mol/L manganese chloride. Add 200ml0.1mol/L potassium permanganate solution to the aluminum-manganese salt mixed solution under rapid stirring, continue stirring for 15min, and then adjust the pH of the solution to 6-8 with sodium hydroxide solution (0.01M-5M); then add 200g 3A molecular sieves with a particle size of 0.2mm-0.5mm were added to the mixture, shaken for 30 minutes, then left to stand and aged at room temperature for 2 hours. After aging, skim off the supernatant, then add a small amount of dilute lye or dilute acid to neutralize, then add 200ml of deionized water, stir and wash for 10 minutes, and separate solid and liquid by filtration. Continue to add deionized water to wash for 3-4 times. After the adsorbent is separated, put it in an oven and bake it at 50°C for 24 hours, then raise the temperature to 90°C and keep it for 12 hours to obtain the aluminum-manganese composite oxide/molecular sieve adsorbent Sample 1.

Example 2 Preparation of aluminum-manganese composite oxide/molecular sieve adsorbent: Prepare 200ml of a mixed solution of 0.25mol/L aluminum sulfate and 0.15mol/L manganese sulfate. Add 200ml0.1mol/L potassium permanganate solution to the aluminum-manganese salt mixed solution under rapid stirring, continue stirring for 30min, and then adjust the pH of the solution to 6-8 with potassium hydroxide solution (0.01M-5M); then add 200g 5A molecular sieves with a particle size of 0.5mm-0.8mm were added to the mixture, shaken for 1 hour, then left to stand and aged at room temperature for 6 hours. After aging, skim off the supernatant, then add a small amount of dilute lye or dilute acid to neutralize, then add 200ml of deionized water, stir and wash for 10 minutes, and separate solid and liquid by filtration. Continue to add deionized water to wash for 3-4 times. After the adsorbent is separated, put it in an oven and bake it at 55°C for 18 hours, then raise the temperature to 100°C and keep it for 10 hours to obtain the aluminum-manganese composite oxide/molecular sieve adsorbent Sample 2.

Example 3 Preparation of aluminum-manganese composite oxide/molecular sieve adsorbent: Prepare 200ml of a mixed solution of 0.45mol/L alum and 0.15mol/L manganese nitrate. Under rapid stirring conditions, add an appropriate amount of hydrogen peroxide solution to the mixed solution of aluminum-manganese salt, so that the molar ratio of oxidant and manganese salt is 1:1, continue stirring for 1 hour, and adjust the concentration of the solution with sodium carbonate solution (0.01M-5M) 6-8; then 200g of 13X molecular sieves with a particle size of 0.8mm-1.0mm were added to the mixture, shaken for 3 hours, then left to stand and aged at room temperature for 10 hours. After aging, skim the supernatant, then add a small amount of dilute lye to neutralize to neutral, then add 200ml deionized water, stir and wash for 10 minutes, separate solid-liquid by filtration, and continue to add deionized solid adsorbent After washing with water for 3-4 times and separating the adsorbent, put it in an oven and bake it at 60°C for 12 hours, then raise the temperature to 110°C and keep it for 8 hours to obtain Al-Mn composite oxide/molecular sieve adsorbent sample 3.

Example 4 Preparation of aluminum-manganese composite oxide/molecular sieve adsorbent: Prepare 200ml of mixed solution of polyaluminum sulfate and manganese sulfate, so that the molar ratio of aluminum to manganese is 6:1. Under rapid stirring conditions, add an appropriate amount of sodium hypochlorite solution to the mixed solution of aluminum-manganese salt, so that the molar ratio of oxidant and manganese salt is 1:1, continue stirring for 1.5h, and adjust the solution concentration with potassium carbonate solution (0.01M-5M). 6-8; Then add 200g of 5A molecular sieves with a particle size of 1.0mm-1.5mm into the mixture, shake for 6h, then stand still and age at room temperature for 16 hours. After aging, skim the supernatant, then add a small amount of dilute lye to neutralize to neutral, then add 200ml deionized water, stir and wash for 10 minutes, separate solid-liquid by filtration, and continue to add deionized solid adsorbent After washing with water for 3-4 times and separating the adsorbent, put it in an oven and bake it at 65°C for 9 hours, then raise the temperature to 150°C and keep it for 6 hours to obtain Al-Mn composite oxide/molecular sieve adsorbent sample 4.

Example 5 Preparation of aluminum-manganese composite oxide/molecular sieve adsorbent: Prepare 200ml of mixed solution of polyaluminum chloride and manganese chloride so that the molar ratio of aluminum-manganese salt is 9:1. Under the condition of rapid stirring, add an appropriate amount of liquid chlorine solution to the mixed solution of aluminum-manganese salt, so that the molar ratio of oxidant and manganese salt is 1:1, continue to stir for 2 hours, and adjust the concentration of the solution with sodium hydroxide solution (0.01M-5M) 6-8; then 200g of 13X molecular sieves with a particle size of 1.5mm-1.7mm were added to the mixture, shaken for 12h, then left to stand and aged at room temperature for 24 hours. After aging, skim the supernatant, then add a small amount of dilute lye to neutralize to neutral, then add 200ml deionized water, stir and wash for 10 minutes, separate solid-liquid by filtration, and continue to add deionized solid adsorbent After washing with water for 3-4 times and separating the adsorbent, put it in an oven and bake it at 75°C for 6 hours, then raise the temperature to 180°C and keep it for 3 hours to obtain Al-Mn composite oxide/molecular sieve adsorbent sample 5.

Example 6 Preparation of aluminum-manganese composite oxide/molecular sieve adsorbent: Prepare 200ml of mixed solution of aluminum chloride and manganese chloride so that the molar ratio of aluminum-manganese salt is 18:1. Under rapid stirring conditions, add an appropriate amount of potassium hypochlorite solution to the mixed solution of aluminum-manganese salt, so that the molar ratio of oxidant and manganese salt is 1:1, continue stirring for 2 hours, and adjust the solution concentration with potassium hydroxide solution (0.01M-5M) 6-8; then add 200g of HY-type molecular sieves with a particle size of 1.7mm-2.0mm into the mixture, shake it for 12 hours, then let it stand and age at room temperature for 24 hours. After aging, skim the supernatant, then add a small amount of dilute lye to neutralize to neutral, then add 200ml deionized water, stir and wash for 10 minutes, separate solid-liquid by filtration, and continue to add deionized solid adsorbent After washing with water for 3-4 times and separating the adsorbent, put it in an oven and bake it at 75°C for 6 hours, then raise the temperature to 180°C and keep it for 3 hours to obtain Al-Mn composite oxide/molecular sieve adsorbent sample 5.

Example 7 Application of aluminum-manganese composite oxide/molecular sieve adsorbent in the treatment of arsenic-containing wastewater: the reactor used in the present invention is a glass packed column filled with the prepared aluminum-manganese oxide/molecular sieve adsorbent particles, the column height About 0.8m, diameter 5cm, filling volume 750cm ³ . In a certain arsenic-containing wastewater, the concentration of trivalent arsenic As(III) is 100 μg/L, and pH=7.2. Water is fed from the bottom of the packed column, and water is discharged from the upper end. The flow rate of the incoming water is 50ml/min, and the concentration of arsenic in the discharged water is regularly measured. After about 5400 times the filling volume, the arsenic concentration in the effluent was higher than 10 μg/L.

Example 8 In-situ regeneration of aluminum-manganese composite oxide/molecular sieve adsorbent: When the concentration of arsenic in the effluent water of the packed column is higher than the water quality requirement, stop the water inflow, and after emptying the water in the column, slowly pump in the arsenic from the bottom of the packed column. Alkaline 100ml concentration is 30% sodium hypochlorite solution, then slowly add 100ml 0.5mol/L sodium hydroxide solution from the top of the packed column, the flow rate is 1ml/min. After the addition is completed, it is statically aged for 4 hours, and then the water phase is released, and the packed column is washed with deionized water until the concentration of soluble aluminum-manganese ions in the effluent is lower than the water quality requirement.

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should belong to the protection scope of the appended claims of the present invention.

Claims (9)

1. the preparation method of an aluminium manganese composite oxide modified molecular screen, it is characterized in that: the mixed solution of preparation aluminium salt and manganese salt, under even stirring condition, in aluminium salt and manganese mixed salt solution, slowly add an amount of oxidizing agent solution, continue to stir 15min-2h to guarantee abundant reaction, add appropriate alkaline liquor regulator solution pH value afterwards and be 6-8, adding an amount of molecule then is sieved in the solution, fully vibration earlier, still aging again 2-24h takes out molecular sieve at last and prepares and get through washing and dry run.

2. the preparation method of aluminium manganese composite oxide modified molecular screen according to claim 1 is characterized in that: described aluminum salt solution comprises a kind of in aluminum sulfate, aluminium chloride, polyaluminium sulfate, aluminium polychloride, the alum or it is arbitrarily than mixture; Described manganese salt is selected from a kind of in manganese chloride, manganese sulfate, the manganese nitrate or it is arbitrarily than mixture.

3. the preparation method of aluminium manganese composite oxide modified molecular screen according to claim 1 is characterized in that: it is 1: 1 to 18: 1 that described aluminium salt and manganese salt satisfy aluminium manganese mol ratio, and the reaction time behind the adding oxidant is 15min to 2h.

4. the preparation method of aluminium manganese composite oxide modified molecular screen according to claim 1 is characterized in that: used alkali lye is the mixture of a kind of or its any ratio in NaOH, potassium hydroxide, sodium carbonate, the potash.

5. the preparation method of aluminium manganese composite oxide modified molecular screen according to claim 1 is characterized in that: described oxidant is a permanganate, and the mol ratio of oxidant and described manganese salt is 2: 3.

6. the preparation method of aluminium manganese composite oxide modified molecular screen according to claim 1 is characterized in that: described oxidant is a kind of in hypochlorite, hydrogen peroxide, the liquid chlorine etc., and the mol ratio of oxidant and manganese salt is 1: 1.

7. the preparation method of aluminium manganese composite oxide modified molecular screen according to claim 1, it is characterized in that: described load matrix is selected from the molecular sieve of particle size range 0.2mm-2mm, and its kind is one or more any combination in 3A type, 4A type, 5A type, 13X type and the HY type.

8. the preparation method of aluminium manganese composite oxide modified molecular screen according to claim 1 is characterized in that: after molecular sieve added mixed liquor, duration of oscillation was 0.5-12h, and the temperature of described aging step is that room temperature, digestion time are 2-24 hour.

9. the preparation method of aluminium manganese composite oxide modified molecular screen according to claim 1 is characterized in that: described drying steps is under 50-75 ℃ of condition dry 6-24 hour, is warming up to afterwards 90-180 ℃ of dry 3-12 hour again.