A calculation method for the regeneration efficiency of zeolite

Abstract

The present invention discloses a method for calculating the regeneration efficiency of zeolite, comprising the following steps: (1) determining constants K and n; (2) preparing saturated zeolite and determining the ammonia nitrogen content of the saturated zeolite; (3) regenerating the saturated zeolite and determining the desorption amount of ammonia nitrogen desorbed from the saturated zeolite; (4) calculating the regeneration efficiency of the zeolite when the zeolite desorption reaches equilibrium. The method of the present invention uses the ratio of the ammonia nitrogen content adsorbed by the regenerated zeolite to the ammonia nitrogen content of the saturated zeolite as the judgment basis for the regeneration ability of the zeolite, and can quantitatively measure the regeneration ability of the zeolite, thereby providing an important parameter for determining the zeolite raw material. The method of the present invention is simple and effective, and has important significance for the application of the zeolite adsorption process in practical engineering.

Description

Technical Field

[0001] The present invention relates to a process for adsorbing ammonia nitrogen in slightly polluted water by zeolite, and particularly to a method for directly measuring the regeneration efficiency of saturated zeolite. Background Art

[0002] Nitrogen is the main object to be removed in the treatment of slightly polluted water, and it exists in raw water in the forms of organic nitrogen, ammonia nitrogen, nitrite nitrogen and nitrate nitrogen. As one of the inorganic nitrogen, ammonia nitrogen is an important factor leading to water eutrophication. Ammonia nitrogen is harmful to the human body. When ammonia nitrogen enters the human body, it synthesizes nitrosamine compounds and induces canceration. At present, the main methods for removing ammonia nitrogen and organic matter in drinking water sources are biological method, adsorption method and membrane method. Zeolite is a widely distributed natural ore, and its main components are metal ions such as Na, Ca, Ba and Mg. Zeolite belongs to an inorganic ion exchanger, has strong selectivity and adsorption for ammonia nitrogen, has a low cost, and has the characteristic of high removal rate when used as an adsorption carrier. The method of using zeolite to adsorb ammonia nitrogen has the advantages of good effect, less investment, simple process and easy operation.

[0003] Zeolite has a good adsorption effect on ammonia nitrogen. After the zeolite is saturated with adsorption, a desorbing agent needs to be used to regenerate the zeolite. The regenerated zeolite can be reused, thereby reducing the dosage of zeolite and improving economic benefits. Under certain conditions, the process of detaching ammonia nitrogen from saturated zeolite is called desorption, which can be considered as the reverse process of adsorption. Therefore, it is feasible to quickly measure the regeneration efficiency of saturated zeolite under static test conditions by the ability of zeolite to adsorb and desorb ammonia nitrogen. The ratio of the ammonia nitrogen content adsorbed by the regenerated zeolite to the ammonia nitrogen content of the saturated zeolite can be used as the judgment basis for the regeneration ability of zeolite. Since the application of zeolite in actual projects is less, how to select a zeolite with stronger regeneration ability, reduce the input of adsorption raw materials, and reduce the amount of solid waste is of great significance for the application of zeolite adsorption in actual projects. Summary of the Invention

[0004] In order to overcome the above deficiencies, the purpose of the present invention is to provide a calculation method for the regeneration efficiency of zeolite to solve the problem that there is no method for quickly measuring the regeneration ability of zeolite in the prior art.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The present invention provides a calculation method for the regeneration efficiency of zeolite, including the following steps:

[0007] (1) Determine the constants K and n;

[0008] (2) Take zeolite with a mass of m to adsorb NH4 with a concentration of C1 and a volume of V1 +The ammonia nitrogen solution or slightly polluted water is repeatedly operated on multiple times, and the concentration C of NH4 in the ammonia nitrogen solution or slightly polluted water after the i-th adsorption of zeolite is detected. + until the concentration of NH4 in the ammonia nitrogen solution or slightly polluted water no longer changes, a saturated zeolite is prepared, and the ammonia nitrogen content of the saturated zeolite is determined. 2i +

[0009] (3) The saturated zeolite with a mass of m is regenerated with a desorbing liquid with a volume of V2. After desorption equilibrium, the concentration C3 of NH4 in the desorbing liquid is detected to determine the desorption amount of ammonia nitrogen desorbed from the saturated zeolite. +

[0010] (4) Calculate the zeolite regeneration efficiency: The ratio of the desorption amount of ammonia nitrogen desorbed from the saturated zeolite to the ammonia nitrogen content of the saturated zeolite is defined as the zeolite regeneration efficiency η. The calculation formula for the zeolite regeneration efficiency is:

[0011]

[0012] where C1 is the concentration of NH4 in the ammonia nitrogen solution or slightly polluted water adsorbed by the zeolite, C is the concentration of NH4 in the ammonia nitrogen solution or slightly polluted water after the i-th adsorption of the zeolite, V1 is the volume of the ammonia nitrogen solution or slightly polluted water, C3 is the concentration of NH4 in the desorbing liquid after desorption, V2 is the volume of the desorbing liquid, m is the mass of the zeolite, and K and n are constants. + 2i + +

[0013] In the present invention, the adsorption amount (mg / g) and desorption amount (mg / g) of the zeolite respectively represent the adsorption capacity and desorption capacity of the zeolite. By measuring the ammonia nitrogen content in the solution after adsorption and the ammonia nitrogen content in the desorbing liquid under the regeneration conditions of the saturated zeolite, the regeneration efficiency of a certain zeolite under certain conditions can be calculated, and then its regeneration ability and adsorption ability when put back into production can be judged.

[0014] The ratio of the ammonia nitrogen content adsorbed by the regenerated zeolite to the ammonia nitrogen content of the saturated zeolite is used as the judgment basis for the zeolite regeneration ability.

[0015] Furthermore, in step (1), the constants K and n are calculated and obtained by the following method:

[0016] (1-1) Ammonia nitrogen solutions with volumes of V1 and different NH4 concentrations C1 are respectively prepared. Zeolite with a mass of m is added to each ammonia nitrogen solution for ammonia nitrogen adsorption. After adsorption equilibrium, the concentration C2 of the remaining NH4 in each ammonia nitrogen solution is measured. + +

[0017] (1-2) With ​​​​​​​​​Taking the y-axis as the y-axis and lgC2 as the x-axis, fitting a straight line, the straight line relationship formula 1 is obtained as follows: Wherein, C1 is the concentration of NH4 in the ammonia nitrogen solution before adsorption + The concentration of C2 is the concentration of NH4 in the ammonia nitrogen solution after adsorption + The concentration of V1 is the volume of the ammonia nitrogen solution, m is the mass of the zeolite, and K and n are constants;

[0018] (1-3) Using function plotting software, substitute the data measured in step (1-1) into formula 1 for straight line fitting to obtain a straight line formula in the form of y = ax + b, where a is expressed as 1 / n and b is expressed as lgK, that is, the constant n = 1 / a and K = 10 b .

[0019] Furthermore, in step (2), during the adsorption process, a six-link coagulation test stirrer is used for stirring to enable the zeolite to adsorb ammonia nitrogen in the liquid in the ammonia nitrogen solution or slightly polluted water.

[0020] Furthermore, in step (3), during the desorption process, a six-link coagulation test stirrer is used for stirring to enable the saturated zeolite to desorb ammonia nitrogen in the desorbing solution.

[0021] Furthermore, the concentration detection operation of NH4 in steps (2) and (3) is as follows: Take a certain amount of water sample for detection, filter it through a 0.45μm syringe filter membrane filter, and measure the concentration of NH4 in the water sample by the Nessler reagent spectrophotometry using a spectrophotometer. + The concentration of. + The concentration of.

[0022] Based on the characteristics of zeolite adsorbing and desorbing ammonia nitrogen under static test conditions, the present invention uses the Nessler reagent spectrophotometry to measure the ammonia nitrogen concentration desorbed by unit zeolite in unit volume solution, and calculates the regeneration efficiency of the zeolite according to its proportional relationship with the ammonia nitrogen content of the saturated zeolite.

[0023] In the present invention, when measuring the ammonia nitrogen content, a spectrophotometer is required. Since the turbidity of slightly polluted water is relatively high, when using zeolite to treat slightly polluted water bodies, it is necessary to filter it through a 0.45μm syringe filter membrane filter before measuring the ammonia nitrogen content.

[0024] Compared with the prior art, the present invention provides a calculation method for the regeneration efficiency of zeolite, which has the following beneficial effects:

[0025] The calculation method of the present invention can utilize the ammonia nitrogen adsorption and desorption capabilities of zeolite under static test conditions to quickly calculate the regeneration efficiency of saturated zeolite. The method of the present invention is simple and effective, and can be effectively applied to the measurement of the desorption capacity (mg / g) of saturated zeolite in actual production. At the same time, it also has extraordinary significance for engineering applications: ① Using this method, the desorption amount of saturated zeolite can be calculated according to the characteristics of ammonia nitrogen adsorption and desorption of zeolite under static test conditions, which has guiding significance for the ammonia nitrogen adsorption of zeolite and the desorption capacity of saturated zeolite in actual production; ② Using this concept, the corresponding relationship between the ammonia nitrogen desorption capacity and the regeneration capacity of saturated zeolite can be established, so as to measure the ammonia nitrogen adsorption capacity of regenerated zeolite and the attenuation degree of the adsorption capacity of regenerated zeolite in actual production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 Graph for determining constants K and n for the fitting line. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The following will clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0029] The concept of the present invention is that the adsorption amount (mg / g) and desorption amount (mg / g) of zeolite represent the adsorption capacity and desorption capacity of zeolite respectively. By measuring the ammonia nitrogen content in the solution after adsorption and the ammonia nitrogen content in the desorbing solution under the regeneration conditions of saturated zeolite, the regeneration efficiency of a certain zeolite under certain conditions can be calculated, and then its regeneration capacity and adsorption capacity when put into production again can be judged.

[0030] The following further describes the present invention in combination with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0031] The present invention is universal for the regeneration efficiency of treating saturated zeolite with different desorbing liquids. The general steps are as follows: ① Determine the constants K and n under certain temperature and air pressure conditions. ② Repeatedly adsorb the ammonia-nitrogen solution for multiple times until the concentration of ammonia-nitrogen in the solution no longer changes, and then detect the ammonia-nitrogen content per unit mass of zeolite. ③ Use the desorbing liquid to regenerate the saturated zeolite, and determine the desorption amount of ammonia-nitrogen desorbed from per unit mass of saturated zeolite. ④ Calculate the regeneration efficiency of zeolite. At the desorption equilibrium, the ratio of the desorption amount (mg / g) of ammonia-nitrogen desorbed by zeolite to the ammonia-nitrogen content (mg / g) of saturated zeolite is the regeneration efficiency.

[0032] Example

[0033] This example provides a calculation method for the regeneration efficiency of zeolite, including the following steps:

[0034] (1) Determine the constants K and n.

[0035] The constants K and n are obtained through the following method:

[0036] (1-1) Prepare NH4Cl solutions with volumes of V1 (250 ml) and different initial concentrations C1 (5 mg / L, 8 mg / L, 10 mg / L, 12 mg / L, 15 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 40 mg / L, 50 mg / L) respectively with deionized water. Add natural zeolite with a mass of m (1 g) to each concentration of NH4Cl solution for ammonia-nitrogen adsorption. During the adsorption process, stir with a six-joint coagulation test stirrer. After adsorption equilibrium, use the Nessler reagent spectrophotometry method to measure the remaining NH4 + concentration C2 of each solution;

[0037] (1-2) Take as the y-axis and lgC2 as the x-axis to fit a straight line. According to the Freundlich isotherm theory, the straight-line relationship formula 1 is obtained as: where C1 is the concentration of NH4 in the NH4Cl solution before adsorption, + C2 is the concentration of NH4 in the NH4Cl solution after adsorption, + V1 is the volume of the NH4Cl solution, m is the mass of the zeolite, and K and n are constants;

[0038] (1-3) Use professional function plotting software to substitute the data measured in step (1-1) into formula 1 for straight-line fitting. As Figure 1 shown, obtain the relationship between zeolite with respect to lgC2 and The linear fitting equation is y = 0.439x + 0.228, that is, the constant K = 2.8887 and n = 2.2978. The constants K and n vary with changes in external conditions and need to be measured and calculated while ensuring that experimental conditions such as temperature remain unchanged. When measuring the constants K and n, ammonia nitrogen solutions with different concentrations should be prepared according to the ammonium standard stock solution in the national standard and prepared according to the steps of the standard use solution.

[0039] (2) Preparation of saturated zeolite: Take zeolite with a mass m (10 g) and immerse it in an NH4Cl solution with a concentration C1 (50 mg / L) and a volume V1 (1000 ml) for adsorption. During the adsorption process, use a six - joint coagulation test stirrer for stirring. After adsorption, take out the zeolite and wash the residual drugs on the surface with deionized water, then continue to adsorb ammonia nitrogen in another NH4Cl solution and repeat the operation multiple times, and detect the concentration of NH4 + in the NH4Cl solution until the concentration of NH4 + in the NH4Cl solution no longer changes, that is, the zeolite has no ability to continue adsorbing ammonia nitrogen. At this time, the concentration of NH4 + in the NH4Cl solution is 3.59 mg / L, and the zeolite at this time is the saturated zeolite. Calculate the ammonia nitrogen content of the saturated zeolite to be 4.64 mg / g. When detecting the concentration of NH4 + in the NH4Cl solution, first use a 0.45 μm syringe - type membrane filter to take a certain amount of water sample for filtration, and then use the Nessler's reagent spectrophotometry method to measure the concentration C + of NH4 in the water sample through a spectrophotometer. 2i .

[0040] (3) Regeneration of saturated zeolite: Set up three parallel experiments (Experiment 1 - 3), and use a KCl desorbing solution with a volume V2 (200 ml) to regenerate 1 g of saturated zeolite under static experimental conditions. During the desorption process, use a six - joint coagulation test stirrer for stirring. After desorption equilibrium, first use a 0.45 μm syringe - type membrane filter to take a certain amount of water sample for filtration, and then use the Nessler's reagent spectrophotometry method to measure the concentration C3 of NH4 + in the water sample and calculate the desorption amount of ammonia nitrogen desorbed by the saturated zeolite.

[0041] (4) Use to calculate the regeneration efficiency of the saturated zeolite. The calculation results are shown in Table 1 below.

[0042] Table 1 Regeneration conditions of three parallel experiments

[0043] Test 1 Test 2 Test 3 <![CDATA[C3 (mg / L)]]> 3.92 3.96 4.01 η (%) 84.44 84.28 84.08

[0044] The above experiments prove that under relatively stable environmental conditions, the ratio of the ammonia nitrogen desorption capacity of regenerated zeolite to the ammonia nitrogen content of saturated zeolite is relatively stable. Therefore, it is completely feasible to use the ratio of the desorption amount of ammonia nitrogen from regenerated zeolite to the ammonia nitrogen content of saturated zeolite as the basis for judging the regeneration ability of zeolite.

[0045] The method of the present invention has great advantages in quickly measuring the regeneration efficiency of saturated zeolite, and is simple and easy to implement. It can be widely applied to laboratory and practical production applications, and has good applicability.

[0046] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0047] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for calculating the regeneration efficiency of zeolite, characterized in that, It includes the following steps: (1) Determine the constants K and n; (2) Take a zeolite with a mass m and an adsorption concentration of C1 and a volume of V1 containing NH4 + The ammonia nitrogen solution or slightly polluted water is adsorbed by zeolite for several times, and the NH4 + The concentration of C 2i , until the NH4 in ammonia nitrogen solution or slightly polluted water + After the concentration no longer changes, a saturated zeolite is obtained, and the ammonia nitrogen content of the saturated zeolite is determined; (3) Regenerate the saturated zeolite with a mass of m using a desorbing liquid with a volume of V2. After desorption equilibrium, detect the concentration C3 of NH4 + in the desorbing liquid and determine the desorption amount of ammonia nitrogen desorbed from the saturated zeolite; (4) Calculate the zeolite regeneration efficiency: Define the ratio of the desorption amount of ammonia nitrogen from the saturated zeolite to the ammonia nitrogen content of the saturated zeolite as the zeolite regeneration efficiency η. The calculation formula for the zeolite regeneration efficiency is: Among them, C1 is the concentration of NH4 in the zeolite-adsorbed ammonia-nitrogen solution or slightly polluted water + , C 2i is the concentration of NH4 in the ammonia-nitrogen solution or slightly polluted water after the i-th adsorption of zeolite + , V1 is the volume of the ammonia-nitrogen solution or slightly polluted water, C3 is the concentration of NH4 in the desorbing solution after desorption + , V2 is the volume of the desorbing solution, m is the mass of the zeolite, and K and n are constants.

2. The calculation method of the zeolite regeneration efficiency according to claim 1, characterized in that: In step (1), the constants K and n are obtained by the following calculation method: (1-1) Prepare ammonia-nitrogen solutions with volumes of V1 and different NH4 + concentrations C1 respectively. Add zeolite with a mass of m to each ammonia-nitrogen solution for ammonia-nitrogen adsorption. After adsorption equilibrium, measure the remaining NH4 + concentration C2 in each ammonia-nitrogen solution; (1-2) Using as the y-axis and lgC2 as the x-axis, fitting a straight line, the obtained straight-line relationship formula 1 is: where C1 is the concentration of NH4 in the ammonia nitrogen solution before adsorption + and C2 is the concentration of NH4 in the ammonia nitrogen solution after adsorption + , V1 is the volume of the ammonia nitrogen solution, m is the mass of the zeolite, and K and n are constants; (1-3) Using function plotting software, substitute the data measured in step (1-1) into Formula 1 for linear fitting to obtain a linear formula in the form of y = ax + b, where a is expressed as 1 / n and b is expressed as lgK, that is, obtain the constants n = 1 / a and K = 10 b .

3. The calculation method of the zeolite regeneration efficiency according to claim 1, characterized in that: In step (2), during the adsorption process, use a six-joint coagulation test stirrer to stir so that the zeolite adsorbs ammonia nitrogen in the liquid in the ammonia nitrogen solution or slightly polluted water.

4. The calculation method of the zeolite regeneration efficiency according to claim 1, wherein: In step (3), during the desorption process, use a six-joint coagulation test stirrer to stir so that the saturated zeolite desorbs ammonia nitrogen in the desorbing solution.

5. The calculation method of the zeolite regeneration efficiency according to claim 1, wherein The concentration detection operation of NH4 in steps (2) and (3) is as follows: Take a certain detection volume of water sample, filter it through a 0.45μm syringe filter membrane filter, and determine the concentration of NH4 in the water sample by the Nessler's reagent spectrophotometry using a spectrophotometer for the filtered water sample. + The concentration detection operation of NH4 in steps (2) and (3) is as follows: Take a certain detection volume of water sample, filter it through a 0.45μm syringe filter membrane filter, and determine the concentration of NH4 in the water sample by the Nessler's reagent spectrophotometry using a spectrophotometer for the filtered water sample. + The concentration.

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