Method for predicting maximum adsorption capacity of humic acid to weak acid organic pollutants and application

Abstract

The application discloses a method for predicting the maximum adsorption capacity of humic acid to weak acid organic pollutants and application. The application adds weak acid organic pollutants into a humic acid solution, fully stirs and mixes, and completes the adsorption of humic acid to the weak acid organic pollutants; the maximum adsorption capacity is obtained by changing the concentration and type of the weak acid organic pollutants, a linear relationship between the maximum adsorption capacity and |ΔpK a is established, and an equation is obtained; the pK a of the weak acid organic pollutants to be measured is calculated, |ΔpK a between the weak acid organic pollutants and humic acid is calculated, the maximum adsorption capacity of the weak acid organic pollutants to be measured is predicted according to the equation, and the prediction process is simple and the accuracy is high.

Description

Technical Field

[0001] This invention belongs to the technical field of environmental chemistry and environmental pollution control, and specifically relates to a method and application for predicting the maximum adsorption capacity of humic acid for weak acidic organic pollutants. Background Technology

[0002] With the rapid development of industry and agriculture, the environmental input of industrial waste, pesticides, fertilizers, and pharmaceuticals is constantly increasing. More and more weakly acidic organic pollutants, characterized by high toxicity, high accumulation, recalcitrant degradation, and long-distance migration, are entering the natural environment, posing potential negative impacts on ecology and human health. Humic acid, a major component of soil, contains complex structures such as benzene rings, hydroxyl groups, and carboxyl groups. It can interact with weakly acidic organic pollutants through adsorption, altering their migration, transformation, and fate, further affecting their bioaccumulation and biotoxicity. However, the maximum adsorption capacity of humic acid for weakly acidic organic pollutants needs to be determined through isothermal adsorption experiments, a cumbersome and complex process. Summary of the Invention

[0003] The primary objective of this invention is to overcome the shortcomings and deficiencies of the prior art and to provide a method for predicting the maximum adsorption capacity of humic acid for weak acidic organic pollutants.

[0004] Another object of the present invention is to provide an application of the above-described method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants includes the following steps:

[0007] (1) Add weak acid organic pollutants to the humic acid solution and stir thoroughly to complete the adsorption of weak acid organic pollutants by humic acid; by changing the type and concentration of weak acid organic pollutants, the maximum adsorption capacity is obtained, and the relationship between the maximum adsorption capacity and |ΔpK is established. a The linear relationship between | is used to obtain the equation, where x is |ΔpK a |, where y is the predicted maximum adsorption capacity;

[0008] (2) By measuring the pK of the weak acid organic pollutants to be tested a Calculate the |ΔpK| between it and humic acid. a Based on the equation obtained in step (1), the maximum adsorption capacity of the weak acid organic pollutant to be tested is predicted.

[0009] The humic acid solution described in step (1) is preferably prepared by the following steps: humic acid particles are added to a solution containing 0.1 mol / L NaCl and 0.01 mol / L NaOH, stirred until fully dissolved, and then the pH is adjusted to 6-7 with 1 mol / L HCl solution. Humic acid contains a large number of weak acid groups and is not easily soluble in neutral or acidic solutions; therefore, an alkaline solution is used to accelerate dissolution, and the pH is adjusted to the natural pH value using dilute hydrochloric acid solution. NaCl is added to simulate the ionic strength under natural conditions.

[0010] The concentration of the humic acid solution is 40-60 mg / L; more preferably 50 mg / L.

[0011] The preferred pH value is 6.5.

[0012] The preferred conditions for thorough mixing in step (1) are as follows: reaction at 100-150 rpm and 24-26°C in the dark for 60-80 h; more preferably, reaction at 120 rpm and 25°C in the dark for 72 h.

[0013] The weak acid organic pollutants mentioned in step (1) include, but are not limited to, mandelic acid, 2-naphthoic acid, benzoic acid, p-nitrophenol, 2,3-dichlorophenol, p-hydroxyacetophenone and phenol.

[0014] The concentration mentioned in step (1) is preferably 0.003 to 0.24 mmol / L; more preferably 0.003, 0.009, 0.015, 0.021, 0.027, 0.033, 0.039, 0.045, 0.051, 0.06, 0.07, 0.09, 0.12, 0.16, 0.2, or 0.24 mmol / L.

[0015] The steps to obtain the maximum adsorption capacity described in step (1) are as follows: the solution that has completed the adsorption of weak acid organic pollutants by humic acid is passed through a 0.22 μm aqueous membrane to remove the precipitated humic acid. Then, the content of weak acid organic pollutants in the filtrate is measured by high performance liquid chromatography, the adsorption amount is calculated, and the maximum adsorption capacity is further obtained.

[0016] The above method for predicting the maximum adsorption capacity of humic acid for weak acid organic pollutants can provide adsorbents for the adsorption treatment of wastewater containing weak acid organic pollutants, and provide theoretical support for predicting the migration and degradation process of weak acid organic pollutants in soil and rivers.

[0017] Principle: This invention utilizes the fact that humic acid molecules contain numerous oxygen-containing functional groups such as carboxyl, hydroxyl, ketone groups, and benzene rings. These functional groups can form weak interactions such as hydrogen bonds and charge-assisted hydrogen bonds with weak acidic organic pollutants, thereby adsorbing these pollutants and influencing their bioaccumulation and biotoxicity. The difference in acid dissociation capacity between humic acid molecules and weak acidic organic pollutants is represented by |ΔpK|. a | will affect the strength of the weak interaction between the two, and will affect the |ΔpK between them. a | By linking the maximum adsorption capacity to the maximum adsorption capacity, a linear correlation is established between the two, thereby predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants. This invention features a simple prediction process, high accuracy, wide application, and high practical value.

[0018] The present invention has the following advantages and effects compared with the prior art:

[0019] The method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants provided by this invention is simple in process, highly accurate, widely applicable, and of high practical value; specifically:

[0020] (1) The present invention solves the problem of selecting the optimal adsorbent for the adsorption treatment of wastewater containing weak acid organic pollutants.

[0021] (1) This invention solves the problem that the determination of the maximum adsorption capacity of humic acid for weak acid organic pollutants is complicated, time-consuming and costly.

[0022] (2) This invention solves the problem that the order of interaction strength between humic acid and weak acid organic pollutants is difficult to predict. By comparing the size of the maximum adsorption capacity, the order of interaction strength can be indirectly predicted.

[0023] (3) This invention provides a theoretical basis for predicting changes in bioaccumulation and biotoxicity of weak acid organic pollutants after they enter the natural environment.

[0024] (4) The prediction process of this invention is simple and has high accuracy. Attached Figure Description

[0025] Figure 1 This is a graph showing the change in the adsorption capacity of humic acid for weakly acidic organic pollutants as a function of pollutant concentration.

[0026] Figure 2 The maximum adsorption capacity varies with |ΔpK a A graph showing the changes in |. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0028] |ΔpK a | represents the difference in acid dissociation constants between humic acid and weakly acidic organic pollutants.

[0029] This invention utilizes the ΔpK between humic acid and weakly acidic organic pollutants. a | is the control variable. Using the maximum adsorption capacity of humic acid for weakly acidic organic pollutants as the prediction target, different |ΔpK values ​​are obtained by changing the types of weakly acidic organic pollutants. a | The effect of humic acid on the maximum adsorption capacity of weakly acidic organic pollutants was investigated, and a linear correlation between the two was established to obtain the maximum adsorption capacity. This prediction method solves the problems of complex and cumbersome process, high time and economic cost in determining the maximum adsorption capacity of humic acid for weakly acidic organic pollutants. It provides a theoretical basis for predicting the interaction strength between humic acid and weakly acidic organic pollutants, as well as the bioaccumulation and biotoxicity of weakly acidic organic pollutants. The prediction process is simple and has high accuracy.

[0030] Example 1

[0031] A method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants includes the following steps:

[0032] (1) Prepare a 50 mg / L humic acid solution using an aqueous solution containing 0.1 mol / L NaCl and 0.01 mol / L NaOH as the solvent, and adjust the pH value to 6.5 with 1 mol / L HCl solution.

[0033] (2) Divide the above solution into 48 portions, each 10 mL, and place them in glass bottles. Seal the bottles to prevent leakage. Divide the bottles into 16 groups, with 3 replicates per group. Add mandelic acid to each portion of the humic acid solution to achieve concentrations of 0.003, 0.009, 0.015, 0.021, 0.027, 0.033, 0.039, 0.045, 0.051, 0.06, 0.07, 0.09, 0.12, 0.16, 0.2, and 0.24 mmol / L, for a total of 16 concentrations.

[0034] (3) Place the above 48 glass bottles into a shaker and shake for 3 days at 120 rpm and 25°C in the dark.

[0035] (4) Remove the shaken sample and pass it through a 0.22 μm aqueous membrane to remove the precipitated humic acid. Measure the mandelic acid concentration of each sample using high-performance liquid chromatography (HPLC) and calculate the adsorption capacity. The adsorption capacity is as follows: Figure 1 As shown.

[0036] Adsorption capacity = (C 末 -C 初 )×10 5 ×0.2;

[0037] Among them, C 初 C represents the initial concentration of mandelic acid in the solution. 末 The concentration of mandelic acid after adsorption is given.

[0038] Example 2

[0039] A method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants includes the following steps:

[0040] (1) Prepare a 50 mg / L humic acid solution using an aqueous solution containing 0.1 mol / L NaCl and 0.01 mol / L NaOH as the solvent, and adjust the pH value to 6.5 with 1 mol / L HCl solution.

[0041] (2) Divide the above solution into 48 portions, each 10 mL, place them in glass bottles, seal them, and divide them into 16 groups, with 3 replicates per group. Add 2-naphthoic acid to each portion of humic acid solution to make the concentrations 0.003, 0.009, 0.015, 0.021, 0.027, 0.033, 0.039, 0.045, 0.051, 0.06, 0.07, 0.09, 0.12, 0.16, 0.2, and 0.24 mmol / L, for a total of 16 concentrations.

[0042] (3) Place the above 48 glass bottles into a shaker and shake for 3 days at 120 rpm and 25°C in the dark.

[0043] (4) Remove the shaken sample and pass it through a 0.22 μm aqueous membrane to remove the precipitated humic acid. Measure the 2-naphthoic acid concentration of each sample using high-performance liquid chromatography (HPLC) and calculate the adsorption capacity. The adsorption capacity is as follows: Figure 1 As shown.

[0044] Adsorption capacity = (C 末 -C 初 )×10 5 ×0.2;

[0045] Among them, C 初 C represents the initial concentration of 2-naphthoic acid in the solution. 末 The concentration of 2-naphthoic acid after adsorption.

[0046] Example 3

[0047] A method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants includes the following steps:

[0048] (1) Prepare a 50 mg / L humic acid solution using an aqueous solution containing 0.1 mol / L NaCl and 0.01 mol / L NaOH as the solvent, and adjust the pH value to 6.5 with 1 mol / L HCl solution.

[0049] (2) Divide the above solution into 48 portions, each 10 mL, place them in glass bottles, seal them, and divide them into 16 groups, with 3 replicates per group. Add benzoic acid to each portion of humic acid solution to make the concentrations 0.003, 0.009, 0.015, 0.021, 0.027, 0.033, 0.039, 0.045, 0.051, 0.06, 0.07, 0.09, 0.12, 0.16, 0.2, and 0.24 mmol / L, for a total of 16 concentrations.

[0050] (3) Place the above 48 glass bottles into a shaker and shake for 3 days at 120 rpm and 25°C in the dark.

[0051] (4) Remove the shaken sample and pass it through a 0.22 μm aqueous membrane to remove the precipitated humic acid. Measure the benzoic acid concentration of each sample using high-performance liquid chromatography (HPLC) and calculate the adsorption capacity. The adsorption capacity is as follows: Figure 1 As shown.

[0052] Adsorption capacity = (C 末 -C 初 )×10 5 ×0.2;

[0053] Among them, C 初 C represents the initial concentration of benzoic acid in the solution. 末 The concentration of benzoic acid after adsorption is given.

[0054] Example 4

[0055] A method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants includes the following steps:

[0056] (1) Prepare a 50 mg / L humic acid solution using an aqueous solution containing 0.1 mol / L NaCl and 0.01 mol / L NaOH as the solvent, and adjust the pH value to 6.5 with 1 mol / L HCl solution.

[0057] (2) Divide the above solution into 48 portions, each 10 mL, place them in glass bottles, seal them, and divide them into 16 groups, with 3 replicates per group. Add p-nitrophenol to each portion of humic acid solution to make the concentrations 0.003, 0.009, 0.015, 0.021, 0.027, 0.033, 0.039, 0.045, 0.051, 0.06, 0.07, 0.09, 0.12, 0.16, 0.2, and 0.24 mmol / L, for a total of 16 concentrations.

[0058] (3) Place the above 48 glass bottles into a shaker and shake for 3 days at 120 rpm and 25°C in the dark.

[0059] (4) Remove the shaken sample and pass it through a 0.22 μm aqueous membrane to remove the precipitated humic acid. Measure the p-nitrophenol concentration of each sample using high-performance liquid chromatography (HPLC) and calculate the adsorption capacity. The adsorption capacity is as follows: Figure 1 As shown.

[0060] Adsorption capacity = (C 末 -C 初 )×10 5 ×0.2;

[0061] Among them, C 初 C represents the initial concentration of p-nitrophenol in the solution. 末 The concentration of p-nitrophenol after adsorption is given.

[0062] Example 5

[0063] A method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants includes the following steps:

[0064] (1) Prepare a 50 mg / L humic acid solution using an aqueous solution containing 0.1 mol / L NaCl and 0.01 mol / L NaOH as the solvent, and adjust the pH value to 6.5 with 1 mol / L HCl solution.

[0065] (2) Divide the above solution into 48 portions, each 10 mL, place them in glass bottles, seal them, and divide them into 16 groups, with 3 replicates per group. Add dichlorophenol to each portion of humic acid solution to make the concentrations 0.003, 0.009, 0.015, 0.021, 0.027, 0.033, 0.039, 0.045, 0.051, 0.06, 0.07, 0.09, 0.12, 0.16, 0.2, and 0.24 mmol / L, for a total of 16 concentrations.

[0066] (3) Place the above 48 glass bottles into a shaker and shake for 3 days at 120 rpm and 25°C in the dark.

[0067] (4) Remove the shaken sample and pass it through a 0.22 μm aqueous membrane to remove the precipitated humic acid. Measure the dichlorophenol concentration of each sample using high-performance liquid chromatography (HPLC) and calculate the adsorption capacity. The adsorption capacity is as follows: Figure 1 As shown.

[0068] Adsorption capacity = (C 末 -C 初 )×10 5 ×0.2

[0069] Among them, C 初 C represents the initial concentration of dichlorophenol in the solution. 末 The concentration of dichlorophenol after adsorption is given.

[0070] Example 6

[0071] A method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants includes the following steps:

[0072] (1) Prepare a 50 mg / L humic acid solution using an aqueous solution containing 0.1 mol / L NaCl and 0.01 mol / L NaOH as the solvent, and adjust the pH value to 6.5 with 1 mol / L HCl solution.

[0073] (2) Divide the above solution into 48 portions, each 10 mL, place them in glass bottles, seal them, and divide them into 16 groups, with 3 replicates per group. Add p-hydroxyacetophenone to each portion of humic acid solution to make the concentrations 0.003, 0.009, 0.015, 0.021, 0.027, 0.033, 0.039, 0.045, 0.051, 0.06, 0.07, 0.09, 0.12, 0.16, 0.2, and 0.24 mmol / L, for a total of 16 concentrations.

[0074] (3) Place the above 48 glass bottles into a shaker and shake for 3 days at 120 rpm and 25°C in the dark.

[0075] (4) Remove the shaken sample and pass it through a 0.22 μm aqueous membrane to remove the precipitated humic acid. Measure the concentration of p-hydroxyacetophenone in each sample using high-performance liquid chromatography (HPLC) and calculate the adsorption capacity. The adsorption capacity is as follows: Figure 1 As shown.

[0076] Adsorption capacity = (C 末 -C 初 )×10 5 ×0.2

[0077] Among them, C 初 C represents the initial concentration of p-hydroxyacetophenone in the solution. 末 The concentration of p-hydroxyacetophenone after adsorption is given.

[0078] Example 7

[0079] A method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants includes the following steps:

[0080] (1) Prepare a 50 mg / L humic acid solution using an aqueous solution containing 0.1 mol / L NaCl and 0.01 mol / L NaOH as the solvent, and adjust the pH value to 6.5 with 1 mol / L HCl solution.

[0081] (2) Divide the above solution into 48 portions, each 10 mL, place them in glass bottles, seal them, and divide them into 16 groups, with 3 replicates per group. Add phenol to each portion of humic acid solution to make the concentrations 0.003, 0.009, 0.015, 0.021, 0.027, 0.033, 0.039, 0.045, 0.051, 0.06, 0.07, 0.09, 0.12, 0.16, 0.2, and 0.24 mmol / L, for a total of 16 concentrations.

[0082] (3) Place the above 48 glass bottles into a shaker and shake for 3 days at 120 rpm and 25°C in the dark.

[0083] (4) Remove the shaken sample and pass it through a 0.22 μm aqueous membrane to remove the precipitated humic acid. Measure the phenol concentration of each sample using high-performance liquid chromatography (HPLC) and calculate the adsorption capacity. The adsorption capacity is as follows: Figure 1 As shown.

[0084] Adsorption capacity = (C 末 -C 初 )×10 5 ×0.2

[0085] Among them, C 初 C represents the initial phenol concentration in the solution. 末 This represents the phenol concentration after adsorption.

[0086] Effect detection:

[0087] A. The effect of the concentration of weakly acidic organic pollutants on adsorption capacity:

[0088] The adsorption capacity of Examples 1-7 was observed as a function of the concentration of weakly acidic organic pollutants (see [reference]). Figure 1 Under otherwise identical conditions, the adsorption capacity gradually increases with the increase of the concentration of weak acidic organic pollutants, from 4 to 12 mmol / Kg at 0.003 mmol to 65 to 201 mmol / Kg at 0.24 mmol.

[0089] B)∣ΔpK a | Effect on maximum adsorption capacity:

[0090] As the concentration of weakly acidic organic pollutants increases, the adsorption capacity gradually increases until it no longer changes, which is the maximum adsorption capacity.

[0091] The maximum adsorption capacity in Examples 1-7 varies with |ΔpK a Observe the changes in | (see Figure 2 At the same temperature and pH value, the change in pH value is related to |ΔpK. a As | increases, the maximum adsorption capacity decreases. When |ΔpK aThe maximum adsorption capacity is lowest at |ΔpK = 5.06, which is 65 mmol / Kg; when |ΔpK a The maximum adsorption capacity is highest at a value of 0.64, reaching 201 mmol / Kg. Therefore, ΔpK₁₀ represents the maximum adsorption capacity. a The smaller the value of |, the higher the maximum adsorption capacity; the two follow a linear relationship. R 2 =0.80531.

[0092] The above experiments show that |ΔpK a | It has a significant impact on the maximum adsorption capacity of humic acid for adsorbing weakly acidic organic pollutants. | ΔpK a When | decreases, the maximum adsorption capacity increases significantly, with a linear relationship of y = -31.83x + 196.44, where x is |ΔpK a |, where y is the maximum adsorption capacity (mmol / Kg). When the pK of a certain weakly acidic organic pollutant is... a When the acid dissociation constant is known, |pK a (pollutant)-pK a (Humic acid) | is the ΔpK between weakly acidic organic pollutants and humic acid. a Substituting | into the above formula, the resulting y (mmol / Kg) is the predicted maximum adsorption capacity. Table 1 shows the pK of each pollutant. a and the |ΔpK| between it and humic acid a |

[0093] Table 1

[0094]

[0095] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants, characterized in that... Includes the following steps: (1) Add weak acid organic pollutants to the humic acid solution and stir thoroughly to complete the adsorption of weak acid organic pollutants by humic acid; by changing the concentration and type of weak acid organic pollutants, the maximum adsorption capacity is obtained, and the relationship between the maximum adsorption capacity and |Δp is established. K a The linear relationship between | is given by y = -31.83x + 196.44, which yields the equation, where x is the value of |Δp. K a |, where y is the predicted maximum adsorption capacity; (2) By measuring the p of the weak acid organic pollutants to be tested K a Calculate the |Δp| ​​between it and humic acid. K a | Based on the equation obtained in step (1), the maximum adsorption capacity of the weak acid organic pollutant to be tested is predicted; The humic acid solution mentioned in step (1) is prepared by the following steps: humic acid particles are added to a solution containing 0.1 mol / L NaCl and 0.01 mol / L NaOH, stirred to dissolve them completely, and then the pH is adjusted to 6-7 with 1 mol / L HCl solution to obtain the humic acid solution. The weak acid organic pollutants mentioned in step (1) include mandelic acid, 2-naphthoic acid, benzoic acid, p-nitrophenol, 2,3-dichlorophenol, p-hydroxyacetophenone and phenol; The steps to obtain the maximum adsorption capacity described in step (1) are as follows: the solution that has completed the adsorption of weak acid organic pollutants by humic acid is passed through a 0.22 μm aqueous membrane to remove the precipitated humic acid, and then the content of weak acid organic pollutants in the filtrate is measured by high performance liquid chromatography to obtain the adsorption amount, and further obtain the maximum adsorption capacity.

2. The method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants according to claim 1, characterized in that: The concentration of the humic acid solution is 40–60 mg / L; The pH value is 6.

5.

3. The method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants according to claim 1, characterized in that: The conditions for thorough mixing described in step (1) are as follows: reaction at 100-150 rpm, 24-26°C in the dark for 60-80 h.

4. The method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants according to claim 1, characterized in that: The concentration is 0.003–0.24 mmol / L.

5. The method for predicting the maximum adsorption capacity of humic acid for weakly acidic organic pollutants according to claim 4, characterized in that: The concentrations are 0.003, 0.009, 0.015, 0.021, 0.027, 0.033, 0.039, 0.045, 0.051, 0.06, 0.07, 0.09, 0.12, 0.16, 0.2, and 0.24 mmol / L.

6. The method for predicting the maximum adsorption capacity of humic acid for weak acid organic pollutants according to any one of claims 1 to 5 is used to provide an adsorbent for the adsorption treatment of wastewater containing weak acid organic pollutants, or to predict the migration and degradation of weak acid organic pollutants in soil and rivers.

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