CN102151546A - A kind of modified zeolite and its preparation method and application - Google Patents

Abstract

The invention discloses a modified zeolite and its preparation method and application. The modified zeolite is prepared by mixing natural zeolite and magnesium oxide, roasting and cooling. Specifically, natural zeolite and magnesium oxide are used as raw materials, and two The mixture is mixed according to the mass ratio of (3-6):1, then roasted at a constant temperature of 100°C-600°C, the time is controlled at 2h-6h, and the modified zeolite is obtained after natural cooling. The modified zeolite can be used in the deammonization nitrogen pretreatment process of biological treatment of aquaculture wastewater, and can be used as an adsorbent for adsorbing high-strength ammonia nitrogen in aquaculture wastewater. The modified zeolite of the invention has strong adsorption capacity for ammonia nitrogen, good ammonia nitrogen adsorption effect, low preparation cost, environmental protection and renewable utilization.

Description

A kind of modified zeolite and its preparation method and application

technical field

The invention relates to a zeolite and its preparation and application, in particular to a modified zeolite and its preparation method and application.

Background technique

The core treatment technology of aquaculture wastewater is microbial treatment technology, that is, through the nitrification and denitrification of microorganisms, ammonia nitrogen is converted into nitrite and nitrate, and then further converted into nitrogen to achieve the purpose of ammonia nitrogen removal. Due to the high concentration of ammonia nitrogen in the aquaculture wastewater, it usually leads to a decrease in the activity of activated sludge, which increases the treatment load and impact load of microorganisms, inhibits the normal progress of the biological treatment process, and also limits the recycling of the treated effluent. In addition, the organic matter content of aquaculture wastewater is low, and an external carbon source is usually required in the microbial treatment process, which increases the cost of sewage treatment. Therefore, before adopting biological treatment, it is necessary to pretreat the aquaculture wastewater to remove ammonia and nitrogen.

At present, air stripping method is often used for pretreatment of ammonia nitrogen removal, but the gaseous nitrogen produced by air stripping method is released into the atmosphere and easily causes secondary pollution; in addition, the investment and operation cost of existing ammonia nitrogen pretreatment is expensive, and air stripping under low temperature conditions is also difficult. not functioning properly. The use of ion exchange or adsorption methods for ammonia nitrogen removal pretreatment has gradually become an inevitable choice for the treatment of wastewater with high ammonia nitrogen content at home and abroad. Among them, the ion exchange and adsorption deammonization nitrogen technology using natural mineral material zeolite as the adsorption material has received extensive attention in the field of sewage treatment at home and abroad.

Natural zeolite is a hydrated crystalline aluminosilicate mineral with a porous crystal structure, high cation exchange capacity and large specific surface area, and the cations in the pores have a strong electrostatic attraction to ammonia nitrogen. Therefore, natural zeolite has a certain adsorption capacity and ion exchange capacity. It can also adsorb certain organic matter while adsorbing ammonia nitrogen, thereby reducing the concentration of ammonia nitrogen in aquaculture wastewater and reducing the stench of aquaculture wastewater to a certain extent. However, since the internal pores and surface structure of natural zeolite are easily blocked, and contain more water-soluble residues and inorganic impurities, the ion exchange capacity and adsorption capacity of natural zeolite are relatively low, and the purpose of efficiently removing pollutants cannot be achieved. Therefore, it is necessary to modify natural zeolite by chemical or physical methods to improve its ability to adsorb ammonia nitrogen.

There are many ways to modify natural zeolite, which are generally divided into two categories: solution soaking modification and high temperature roasting modification. Solution immersion modification is to use inorganic acid solution, inorganic alkali solution or inorganic salt solution to soak natural zeolite. This method can remove some water-soluble residues and inorganic impurities on the surface and inner pores of natural zeolite, and improve the quality of the natural zeolite to a certain extent. The ion adsorption and exchange capacity of zeolite, but there are shortcomings such as long modification soaking time, small increase in ammonia nitrogen adsorption capacity, and it is difficult to remove mineral impurities that are firmly combined with zeolite. High-temperature calcination can remove such impurities to the greatest extent, increase porosity, and enhance the surface activity and adsorption capacity of zeolite. However, a single modification of natural zeolite through high-temperature calcination usually requires a high temperature of 600 ° C to 800 ° C, and the energy consumption is relatively high. High, and easily lead to the destruction of the zeolite structure, so that it loses its adsorption and ion exchange functions.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, provide a modified zeolite with strong ammonia nitrogen adsorption capacity, good ammonia nitrogen adsorption effect, low preparation cost, environmental protection and renewable utilization and its application, and also provide a roasting The preparation method of the modified zeolite has the advantages of low temperature, short roasting period and convenient process operation.

In order to solve the above technical problems, the technical solution proposed by the present invention is a modified zeolite, which is prepared by mixing natural zeolite with magnesium oxide, roasting and cooling.

In the above-mentioned modified zeolite, the mass ratio of the natural zeolite to magnesium oxide is preferably (3-6):1.

As a general technical idea, the present invention also provides a kind of preparation method of above-mentioned modified zeolite, comprises the following steps: take natural zeolite and magnesium oxide as raw material, said natural zeolite and magnesium oxide according to (3～6):1 The mass ratio is mixed evenly, and then the mixture is heated and roasted at a constant temperature. The temperature during roasting is controlled at 100°C to 600°C (preferably 150°C to 400°C), and the roasting time is controlled at 2h to 6h. After natural cooling, the modified Zeolite.

As a general technical concept, the present invention also provides an application of the above-mentioned modified zeolite, specifically, the modified zeolite is used in the pretreatment process of deammonization nitrogen in the biological treatment of aquaculture wastewater, and it is used as a method for adsorbing high-strength ammonia nitrogen in aquaculture wastewater. the adsorbent.

In the above-mentioned application, when the modified zeolite is used as an adsorbent, the amount added is preferably 5g to 60g (most preferably 15g/L) per liter of aquaculture wastewater, and the pH value of the aquaculture wastewater is preferably controlled during the pretreatment process. At 6.5-9.0 (most preferably 7.0-8.0), the concentration of ammonia nitrogen in the aquaculture wastewater is preferably controlled at 600mg/L-1200mg/L, and the temperature is controlled at 25°C-31°C (most preferably 27°C).

In the above application, the stirring condition is preferably as follows: first, stir rapidly at a speed of 300 r/min for 1 min, then stir slowly at a speed of 130 r/min for 10 min, and finally settle for 30 min.

Compared with the prior art, the advantage of the present invention is that the present invention aims at the deficiencies of existing natural zeolite modification methods, and prepares a kind of microstructure and composition different from natural zeolite through the thermal modification method of roasting loaded magnesia. The modified zeolite; in the whole preparation process, the calcination temperature is relatively low, the calcination time and period are short, and the modified zeolite after modification treatment and the aquaculture wastewater are fully contacted and stirred in the reaction tank to carry out the adsorption of ammonia nitrogen. We use the adsorption capacity of the modified zeolite per unit mass to ammonia nitrogen as an index to investigate the ability of the modified zeolite to adsorb ammonia nitrogen of the present invention. By detecting the initial ammonia nitrogen concentration of the aquaculture wastewater and the ammonia nitrogen concentration after adsorption equilibrium, we found that the modified zeolite of the present invention The equilibrium adsorption capacity of ammonia nitrogen can be increased to 140%-200% of the original. It can be seen that the modified zeolite of the present invention has strong adsorption performance for ammonia nitrogen, good adsorption and sedimentation performance, low sludge moisture content, and ideal adsorption and removal effect for high-strength ammonia nitrogen.

In addition, the modified zeolite modification technology provided by the present invention is simple to operate, can be effectively combined with traditional water treatment processes (such as SBR, UASB, etc.), and has good practical application value and industrialization prospect.

Description of drawings

Fig. 1 is the process flow diagram when the modified zeolite of the present invention is applied to the biological treatment of aquaculture wastewater.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Embodiment: a kind of modified zeolite of the present invention and its preparation method and application.

The modified zeolite of the present invention is prepared by mixing natural zeolite and magnesium oxide, calcining and cooling.

The specific operation of the preparation method of the modified zeolite in this embodiment is as follows: using natural zeolite and magnesia as raw materials, the natural zeolite and magnesia are mixed evenly according to the mass ratio of 4:1, and then the mixture is heated and roasted at a constant temperature. Change the temperature control conditions (take values within the range of 100°C to 600°C), control the calcination time at 4.5h (2h to 6h is acceptable), and obtain modified zeolites under different temperature control conditions after natural cooling.

The natural zeolite and the modified zeolite prepared in this example are applied to the deammonization nitrogen pretreatment process of the biological treatment of aquaculture wastewater as shown in Figure 1, and are used as an adsorbent for adsorbing high-strength ammonia nitrogen in the aquaculture wastewater. The performance of adsorbing ammonia nitrogen in wastewater was investigated.

Take by weighing the natural zeolite of 15g and the modified zeolite of equal quality respectively, it is respectively placed in the serial reaction pond of the culture wastewater sample that 1000mL known ammonia nitrogen concentration (844mg/L) is housed, the pH value of culture wastewater is 7.5, The temperature was controlled at 27°C, and then a mixing agitator was used to stir at room temperature to make it fully contact. The stirring conditions were: 300r/min rapid stirring for 1min, then 130r/min slow stirring for 10min, and finally static settling for 30min. Get the supernatant, adopt Nessler's reagent spectrophotometry to measure the concentration of ammonia nitrogen in the effluent after adsorption equilibrium, adopt the following formula (1) to calculate the adsorption capacity Q of zeolite (i.e. the adsorption capacity of unit mass modified zeolite to ammonia nitrogen, unit: mg/g), to judge and compare the adsorption properties of natural clinoptilolite and the modified zeolite of the present invention under different calcination temperature control to ammonia nitrogen.

$\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In formula (1):

C ₀ is the initial concentration of ammonia nitrogen in the culture wastewater sample (unit: mg/L);

C is the final concentration of ammonia nitrogen in the effluent after adsorption equilibrium (unit: mg/L);

m is the amount of zeolite powder (unit: g);

V is the volume of the aquaculture wastewater sample (unit: mL).

The comparative results of the adsorption properties in the above application examples are shown in Table 1 below.

Table 1: Performance comparison of zeolite powder adsorption of ammonia nitrogen

As can be seen from the above table 1, the modified zeolite of the present invention has better adsorption properties to ammonia nitrogen than natural clinoptilolite, wherein the modified zeolite under the roasting condition of 150° C. has the best adsorption performance to ammonia nitrogen, and 150° C. to 400 ° C. °C is the preferred firing temperature range.

The aquaculture wastewater after the above pretreatment is effectively combined with the traditional water treatment process (aerobic SBR), so that the aquaculture wastewater can finally be discharged up to the standard.

Claims (8)

1. a modified zeolite is characterized in that, described modified zeolite is to be mixed with magnesia after roasting, cooling prepare by natural zeolite.

2. modified zeolite according to claim 1 is characterized in that, described natural zeolite and magnesian mass ratio are (3～6): 1.

3. the preparation method of a modified zeolite as claimed in claim 1, may further comprise the steps: with natural zeolite and magnesia is raw material, with described natural zeolite and magnesia according to (3～6): 1 mass ratio mixes, heat temperature raising carries out constant temperature calcining to mixture then, temperature during roasting is controlled at 100 ℃～600 ℃, roasting time is controlled at 2h～6h, obtains modified zeolite after the cooling naturally.

4. the preparation method of modified zeolite according to claim 3 is characterized in that, the temperature during described roasting is controlled at 150 ℃～400 ℃.

5. the application of a modified zeolite as claimed in claim 1 or that prepare as claim 3, it is characterized in that, with described modified zeolite be used for the carrying out a biological disposal upon ammonia nitrogen removal preprocessing process of breeding wastewater, and as the adsorbent of high strength ammonia nitrogen in the absorption breeding wastewater.

6. application according to claim 5, it is characterized in that, addition when described modified zeolite is used as adsorbent is that every liter of breeding wastewater adds 5g～60g, the pH value of breeding wastewater is controlled at 6.5～9.0 in the described preprocessing process, ammonia nitrogen concentration in the breeding wastewater is 600mg/L～1200mg/L, and temperature is controlled at 25 ℃～31 ℃.

7. application according to claim 6 is characterized in that, the addition when described modified zeolite is used as adsorbent is that every liter of breeding wastewater adds 15g, and the pH value of breeding wastewater is controlled at 7.0～8.0 in the described preprocessing process, and temperature is controlled at 27 ℃.

8. according to claim 5,6 or 7 described application, it is characterized in that described stirring condition is: the rotating speed with 300r/min stirs 1min fast earlier, and the rotating speed with 130r/min stirs 10min at a slow speed then, last quiet heavy 30min.

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