CN105688835A - Adsorption material capable of removing ammonia nitrogen in solution and preparation method of adsorption material - Google Patents

Abstract

The invention discloses an adsorption material capable of removing ammonia nitrogen in a solution. A raw material comprises cotton straws; and the cotton straws are combusted for 1-3 hours at 290 DEG C to 350 DEG C without oxygen to obtain the adsorption material capable of removing the ammonia nitrogen in the solution. The invention further provides a preparation method of the adsorption material capable of efficiently removing the ammonia nitrogen in the solution; a biological carbon adsorbent prepared by the method can be used for efficiently removing the ammonia nitrogen in the solution and the adsorption amount can reach about 209.4mg/g; and the ammonia nitrogen adsorption mount of the modified adsorbent can reach about 518.9mg/g.

Description

Adsorption material for removing ammonia nitrogen in solution and preparation method thereof

technical field

The invention relates to an adsorption material for removing ammonia nitrogen in a solution and a preparation method thereof, belonging to the technical field of water pollution control.

Background technique

As the earth's water resources become increasingly scarce, people pay more and more attention to the protection of the water environment and the regeneration and reuse of sewage (rain) water resources. On the one hand, many natural water bodies in China are currently seriously polluted, and eutrophication has caused the water bodies to degrade to Class VI or inferior to Class VI. Water body restoration is an urgent problem to be solved at present; on the other hand, the treatment processes of urban sewage treatment plants are mostly secondary Treatment, the effluent can generally reach the I-level B standard of the "Comprehensive Sewage Discharge Standard". With the strengthening of environmental protection in the country, the water quality requirements of the sewage plant effluent have been raised to the I-level A standard. Therefore, it is necessary to increase the amount of sewage in the sewage plant. Advanced treatment process. Thirdly, rainwater is a fresh water resource, and rainwater recycling is also the fastest and most efficient way to save freshwater resources. Rainwater treatment requires a simple, efficient, and energy-saving treatment method. As an advanced water treatment process, adsorption has been widely used. An important factor affecting the treatment effect of adsorption method is the adsorption material used. The ion exchange adsorption method mainly treats low-concentration inorganic ammonia-nitrogen wastewater. Commonly used adsorbents include: zeolite, activated carbon, cinder, alumina, silica gel, diatomaceous earth, kaolin, medical stone and ion exchange resin. Among the existing adsorption materials, zeolite has the best adsorption effect on ammonia nitrogen, but because many sewage contains coexisting cations such as Ca ²⁺ , the exchange capacity of zeolite will be irreversibly reduced. Activated carbon and activated carbon fiber mainly adsorb nitrogen in the form of ammonia molecules in water, which has no selectivity and limited adsorption capacity, so the denitrification efficiency is very low. Coal-based adsorbents have good adsorption effect, but are expensive and difficult to regenerate. The adsorption capacity and adsorption speed of the adsorption material determine the effect of the adsorption method. However, these materials are either expensive or have low adsorption efficiency. Therefore, it is urgent to develop targeted, applicable and strong adsorbents to meet social and market demands.

Contents of the invention

The technical problem to be solved by the invention is to overcome the existing defects and provide an adsorption material for removing ammonia nitrogen in a solution and a preparation method thereof.

In order to solve the problems of the technologies described above, the present invention provides the following technical solutions:

An adsorption material for removing ammonia nitrogen in a solution, characterized in that: the raw material is cotton stalks, and the cotton stalks are anaerobically fired at 290°C-350°C (preferably 300°C) for 1-3 (preferably 2) hours to remove Adsorption material for ammonia nitrogen in solution.

Cotton stalk raw materials are treated at high temperature under the condition of anoxic or low oxygen, and cracking will occur. After the oil and gas in the biomass are burned, the remaining highly aromatic and insoluble solid matter is a kind of charcoal with extremely high carbon content. Microscopically, it has a regular hexagonal structure similar to graphite; macroscopically, it has no crystal structure, but it has a huge specific surface area and many pore structures. A large number of hydroxyl groups, ethylenic bonds and aromatic structure substances are generated on the surface, thus forming a porous structure biochar adsorbent with well-developed pores.

In the above scheme, it is preferred that the cotton stalks are modified with a 1.0 mol/L alkaline solution.

In any of the above schemes, preferably, the base is NaOH or KOH.

After the cotton stalks were modified with 1.0mol/L NaOH or 1.0mol/L KOH, the specific surface area and total pore volume of biochar were improved to a certain extent, and the hydroxyl groups and ethylenic bonds on the surface also increased.

In any of the above schemes, preferably, the cotton stalks and the alkali solution are added to the alkali solution according to the solid-to-liquid ratio of 1g:2.0mL-1g:3.0ml (preferably 1g:2.5mL), soaked for 1-3 (preferably 2) After 1 hour, dry at 100°C-110°C (preferably 105°C).

In any of the above schemes, it is preferred that the anaerobic fired product is ground and sieved through a 16-20 mesh to collect the intercepted product, then washed with water until the pH value is constant, and baked at 100°C-110°C (preferably 105°C). Dry and set aside.

The present invention also provides a preparation method for the adsorption material for removing ammonia nitrogen in the solution, wherein the cotton stalks are anaerobically fired at 290°C-350°C (preferably 300°C) for 1-3 (preferably 2) hours to obtain the removal solution Adsorbent material for ammonia nitrogen.

In any of the above schemes, preferably, the preparation method further includes modification of raw materials.

Preferably in any of the above schemes, the modification method is: the cotton stalk and the alkali solution are added to the alkali solution according to the solid-to-liquid ratio of 1g:2.0mL-1g:3.0ml (preferably 1g:2.5mL) After soaking for 1-3 (preferably 2) hours, place it in 100°C-110°C (preferably 105°C) for drying.

In any of the above schemes, preferably, the alkaline solution is a 1.0 mol/L NaOH or KOH solution.

In any of the above schemes, it is preferred that the anaerobic fired product is ground and sieved through a 16-20 mesh to collect the intercepted product, then washed with water until the pH value is constant, and baked at 100°C-110°C (preferably 105°C). Dry and set aside.

Adsorbent material of the present invention and modified adsorbent material, the productive rate in the manufacturing process of these two kinds of adsorbents is about 39.95%, and adsorbent specific surface area and pore diameter are shown in the following table:

Table 1: Adsorbent specific surface area and pore size

Adsorbent Specific surface area (m ² /g) Total pore area (cm ² /g) Average Pore Diameter (nm) cotton stalk biochar 108.59 0.270 9.94 Modified Cotton Stalk Biochar 121.69 0.292 9.60

Beneficial effects of the present invention: the present invention provides an adsorbent material for efficiently removing ammonia nitrogen in a solution and a production method thereof. The biochar adsorbent produced by this method can efficiently remove ammonia nitrogen in a solution, and the adsorption capacity can reach 209.4mg/ g, after modification, the adsorption capacity of ammonia nitrogen can reach about 518.9 mg/g.

Biochar is a solid with a relatively stable structure, and has abundant raw material resources and strong adsorption performance. From the perspective of waste resource utilization, compared with the currently commonly used adsorbents, the present invention has the following salient features:

1. The raw materials of the adsorbent have wide sources and are cheap. Cotton stalks, as a kind of agricultural waste, have a large number of cotton stalks that can be used in the vast rural areas of our country, and basically do not need money or only need a small price to buy, which realizes the reuse of resources, protects the environment, and improves its economic effect. Pollution control with waste has a good application prospect;

2. The manufacturing method of the adsorbent is simple. Adsorbent 1 only needs to fire the raw materials at high temperature under anoxic conditions; adsorbent 2 also only needs to soak the raw materials in NaOH or KOH solution, and then fire them at high temperature in anoxic condition, the raw materials are simple and do not need to be Additional ratio, no need to add surfactant or surface catalyst;

3. High adsorption capacity of the adsorbent. The adsorption capacity of adsorbent 1 can reach about 209.4 mg/g, and the adsorption capacity of adsorbent 2 can reach about 518.9 mg/g;

4. The adsorption speed is fast. The adsorbent can adsorb and remove the ammonia nitrogen in the sewage within 5 hours, and the removal efficiency is high;

5. The adsorbent after adsorption can be reused. The adsorbent after adsorbing ammonia nitrogen can be used as fertilizer for soil improvement. The ammonia nitrogen adsorbed on the adsorbent can be slowly released in the soil, providing a source of nitrogen fertilizer for crop growth;

6. The raw materials of the patent CN201310266746 are biomass wastes, but in this application, there is no need to add combustion aids and surfactants, and there is no need to strictly mix with other materials in the process of making the adsorbent. The preparation process of the present application is simple, and the adsorption capacity of ammonia nitrogen is dozens of times that of the existing adsorption materials.

detailed description

Preferred embodiments of the present invention are described below, and it should be understood that the preferred embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

Example 1:

An adsorption material for removing ammonia nitrogen in a solution: the raw material is cotton stalks, and the cotton stalks are anaerobically fired at 300°C for 2 hours, and the anoxic fired products are ground and passed through a 16-20 mesh sieve to collect the retentate. Then wash it with water until the pH value is constant, and dry it at 105°C for later use, so as to obtain an adsorption material for removing ammonia nitrogen in the solution.

Example 2:

An adsorption material for removing ammonia nitrogen in a solution: the raw material is cotton stalks, and the cotton stalks are modified by 1.0 mol/L NaOH or KOH solution. The modification method is as follows: the cotton stalks and the alkali solution are added into the alkali solution according to the solid-to-liquid ratio of 1g:2.5mL, soaked for 2 hours, and dried at 105°C.

The modified cotton stalks are anoxic fired at 300°C for 2 hours, and the anoxic fired product is ground and passed through a 16-20 mesh sieve to collect the intercepted product, then rinsed with water until the pH value is constant, and dried at 105°C Standby, must remove the adsorption material of ammonia nitrogen in the solution.

Example 3:

The raw material of an adsorption material for removing ammonia nitrogen in a solution is cotton stalks, and the cotton stalks are anaerobically fired at 290°C for 1 hour, and the anoxic fired products are ground and passed through a 16-20 mesh sieve to collect the retentate, and then Rinse with water until the pH value is constant, dry at 100°C for later use, and obtain an adsorption material for removing ammonia nitrogen in the solution.

Example 4:

An adsorption material for removing ammonia nitrogen in a solution: the raw material is cotton stalks, and the cotton stalks are modified by 1.0 mol/L NaOH or KOH solution. The modification method is as follows: the cotton stalks and the alkali solution are added into the alkali solution according to the solid-to-liquid ratio of 1g:2.0mL, soaked for 2 hours, and dried at 100°C.

The modified cotton stalks are anoxic fired at 290°C for 1 hour, and the anoxic fired product is ground and passed through a 16-20 mesh sieve to collect the intercepted product, then rinsed with water until the pH value is constant, and dried at 100°C Standby, must remove the adsorption material of ammonia nitrogen in the solution.

Example 5:

An adsorption material for removing ammonia nitrogen in a solution: the raw material is cotton stalks, and the cotton stalks are anaerobically fired at 310°C for 3 hours, and the anoxic fired products are ground and passed through a 16-20 mesh sieve to collect the retentate. Then wash it with water until the pH value is constant, and dry it at 110°C for later use, so as to obtain an adsorption material for removing ammonia nitrogen in the solution.

Embodiment 6:

An adsorption material for removing ammonia nitrogen in a solution: the raw material is cotton stalks, and the cotton stalks are modified by 1.0 mol/L NaOH or KOH solution. The modification method is as follows: the cotton stalks and the alkali solution are added into the alkali solution according to the solid-to-liquid ratio of 1g:3.0mL, soaked for 3 hours, and dried at 110°C.

The modified cotton stalks were anoxic fired at 310°C for 3 hours, and the anoxic fired product was ground and passed through a 16-20 mesh sieve to collect the intercepted product, then rinsed with water until the pH value was constant, and dried at 110°C Standby, must remove the adsorption material of ammonia nitrogen in the solution.

Experimental Example 1: Adsorption Experimental Method

The optimum adsorption pH value of adsorbent 1 (Example 1) is about pH=10.0, and the optimum adsorption pH value of Adsorbent 2 (Example 2) is about pH=7.0.

The adsorption conditions at different temperatures indicated that the process of adsorption of ammonia nitrogen by the adsorbent was an exothermic reaction.

When the initial concentration of ammonia nitrogen is 50mg/l, take 50ml of ammonia nitrogen solution, add 0.1g of the prepared adsorbent (1 or 2) into a 50ml centrifuge tube, shake the reaction at 25°C at a speed of 120r/min, and then Samples were taken at different times by vacuum filtration to determine the content of ammonia nitrogen. Adsorbent 1 basically reached the adsorption equilibrium after 2 hours of adsorption, and Adsorbent 2 basically reached the adsorption equilibrium after 5 hours of adsorption.

Through the adsorption test of ammonia nitrogen solutions with different initial concentrations, take 50ml of ammonia nitrogen solutions with different concentrations, add 0.1g of the prepared adsorbent (1 or 2) into a 50ml centrifuge tube, and at 25°C, the speed of 120r/min The reaction was shaken for 24 hours, and the sample was vacuum filtered to determine the content of ammonia nitrogen. The Langmuir model is used to fit the experimental results, and its mathematical expression is as follows:

${\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; KC</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; KC</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}$

In the formula: q _e is the adsorption capacity of the unit adsorbent at equilibrium (mg/g); C _e is the solution concentration at equilibrium (mg/l); q _m is the maximum adsorption capacity (mg/g); K is the Langmuir equilibrium constant .

The experimental results of adsorbent 1 are shown in Table 2. The maximum adsorption capacity of adsorbent 1 under the Langmuir model is about 209.4 mg/g; the experimental results of adsorbent 2 are shown in Table 3, and the maximum adsorption capacity of adsorbent 2 is about 518.9 mg/g. The parameters simulated by the Langmuir model are shown in Table 4.

Table 2: Adsorption experimental data of cotton stalk biochar

Table 3: Adsorption experimental data of modified cotton stalk biochar

Table 4: Langmuir model simulation parameters

Langmuir model parameters cotton stalk biochar Modified Cotton Stalk Biochar R ² 0.872 0.84 _Smax 209.4 518.90 k 0.003 0.005

The invention provides two kinds of biochar adsorbents for efficiently removing ammonia nitrogen in solution—cotton stalk biochar and modified cotton stalk biochar, and provides the manufacturing method and experimental research method of the two kinds of biochar.

Finally, it should be noted that: the above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it still The technical solutions recorded in the foregoing embodiments may be modified, or some technical features thereof may be equivalently replaced. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. An adsorption material for removing ammonia nitrogen in a solution, characterized in that: the raw material is a cotton stalk, and the cotton stalk is anaerobically fired at 290°C-350°C for 1-3 hours to obtain an adsorption material for removing ammonia nitrogen in a solution. 2. The adsorption material according to claim 1, characterized in that: the cotton stalks are modified with a 1.0 mol/L alkaline solution. 3. The adsorption material according to claim 2, characterized in that: the alkali is NaOH or KOH. 4. The adsorption material according to claim 3, characterized in that: the modification method is: the cotton stalk and the alkali solution are added in the alkali solution according to the solid-to-liquid ratio of 1g:2.0mL-1g:3.0ml, After soaking for 1-3 hours, dry at 100°C-110°C. 5. The adsorption material according to any one of claims 1 to 4, characterized in that: the anoxic fired product is ground and passed through a 16-20 mesh sieve to collect the retentate, and then washed with water until the pH value is constant, Dry at 100°C-110°C for later use. 6. The preparation method of the adsorbent material for removing ammonia nitrogen in the solution according to any one of claims 1 to 5, characterized in that: the cotton stalk is anaerobically fired at 290°C-350°C for 1-3 hours to obtain Adsorbent material for removal of ammonia nitrogen in solution. 7. The preparation method of the adsorption material for removing ammonia nitrogen in the solution according to claim 6, characterized in that: the preparation method also includes the modification of raw materials. 8. The preparation method of the adsorption material for removing ammonia nitrogen in the solution according to claim 7, characterized in that: the modification method is: the cotton stalk and the alkali solution are added according to the solid-liquid ratio 1g:2.0mL-1g:3.0ml After soaking in the alkaline solution for 1-3 hours, dry at 100°C-110°C. 9. The preparation method of the adsorption material for removing ammonia nitrogen in the solution according to claim 8, characterized in that: the alkaline solution is a 1.0 mol/L NaOH or KOH solution. 10. The preparation method of the adsorbent material for removing ammonia nitrogen in the solution according to any one of claims 6 to 9, characterized in that: the product after anoxic firing is ground and passed through a 16-20 mesh sieve to collect the retentate, and then water Rinse until the pH value is constant, and dry at 100°C-110°C for later use.