CN115465913B - Activated carbon multistage adding method for enhancing removal of micro-pollutants in water - Google Patents
Activated carbon multistage adding method for enhancing removal of micro-pollutants in water Download PDFInfo
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- C—CHEMISTRY; METALLURGY
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Abstract
The invention discloses an activated carbon multi-stage feeding method for enhancing removal of micropollutants in water, and relates to the technical field of environmental protection. The method comprises the following steps: adsorbing the micro-pollutant-water mixed solution by adopting a mode of multistage addition of activated carbon; in the multistage active carbon adding process, the adding frequency N is more than or equal to 2; in the method, the total adding amount of the activated carbon is obtained by calculation according to the adsorption capacity of the activated carbon and the target removal rate of the micropollutants; the micropollutants in the micropollutants-water mixed liquor comprise cyclic acetal compounds. The multistage active carbon adding method provided by the invention can effectively reduce the competition of background organic matters under the complex water quality condition by a step-by-step active carbon adding method, overcomes the defect of large carbon adding amount in the traditional single active carbon adding mode, improves the micro-pollutant adsorption and removal effect, is not required to be combined with other processes, is convenient to operate, and greatly reduces the operation cost of the active carbon process.
Description
Technical Field
The invention belongs to the technical field of environmental protection, and particularly relates to an activated carbon multistage adding method for enhancing removal of micropollutants in water.
Background
The occurrence of micro-pollutants in water can cause harm to human health, and the olfactory substances in the water can also reduce the sensory quality of the water. Activated carbon adsorption is one of the main technical means for removing micropollutants in water treatment, and the removal efficiency of the micropollutants is generally greatly reduced due to adsorption competition of coexisting background organic matters in water. Background organic matters in water are a highly complex mixture and are rich in sources such as humation products of animal and plant residues, metabolites of plankton such as algae in water, organic matters discharged in human production and life, and the like. Meanwhile, the background organic matter can be further converted in water due to chemical actions (such as hydrolysis, biodegradation and the like), so that the molecular composition of the background organic matter is extremely complex, and the concentration and the characteristics of the background organic matter in different water have certain differences. Because trace amount (ng/L-mu g/L) of micro-pollutants in water is usually achieved, and the background organic matter content (mg/L) in natural water (municipal sewage) is high, the active carbon adsorption removal efficiency of the micro-pollutants in the natural water (or municipal sewage) can be remarkably reduced through carbon pore blockage and direct competition of adsorption sites of the background organic matter. In practical water treatment processes, a considerable amount of activated carbon is required to reduce the concentration of micropollutants below a threshold value. Generally speaking, the water plant is difficult to bear the cost pressure caused by high-dosage activated carbon, and the high-dosage activated carbon can block a filter tank, thereby further reducing the water production efficiency of the water plant.
In the existing water treatment, the activated carbon adsorption usually adopts a single-time complete adding mode, and the strong competition of background organic matters causes the common higher consumption of the activated carbon. Water plants typically employ a combination of other processes to reduce the competition for background organics, such as: (1) High-concentration ozone oxidation can remove about 50% of competitive background organic matters, so that the adsorption effect of micro pollutants in ozone treatment water is improved, but the high-concentration ozone treatment cost is high, and harmful byproducts such as bromate and the like can be generated; (2) The removal effect of potassium permanganate oxidation on competitive background organic matters is poor, the adsorption efficiency of micro pollutants in oxidation treatment water can be only improved by 1% -7%, and the increase of potassium permanganate can cause extra cost burden on process operation. Although the combined technology removes competitive organic matters and improves the removal of micro pollutants to a certain extent, the additional technology or the arrangement of adding the medicament greatly increases the running cost of the water treatment technology.
In previous researches, the competitive capacity of small-molecule hydrophobic organic matters in background organic matters is the strongest, and the content of the small-molecule hydrophobic organic matters accounts for about 8% -25% of the total. The component has stronger adsorption capacity generally, has better adsorption effect under lower carbon dosage, and the adsorption process of the activated carbon of background organic matters is highly irreversible, and the adsorbed background organic matters are difficult to desorb and redissolve in water.
Disclosure of Invention
The invention aims to provide an activated carbon multistage feeding method for strengthening removal of micro pollutants in water, which can effectively reduce competition of organic matters under a complex water quality background, overcomes the defect of large carbon feeding amount in the traditional single carbon feeding mode, improves the adsorption removal effect of the micro pollutants, does not need to be combined with other processes, is convenient to operate and greatly reduces the operation cost of the activated carbon process.
The technical scheme adopted by the invention for realizing the purpose is as follows:
a method for enhancing the removal of micropollutants from water, comprising: adsorbing the micro-pollutant-water mixed solution by adopting a mode of multistage addition of activated carbon;
in the multistage active carbon adding process, the adding frequency N is more than or equal to 2;
in the method, the total adding amount of the activated carbon is obtained by calculation according to the adsorption capacity of the activated carbon and the target removal rate of the micropollutants;
the micro-pollutants in the micro-pollutant-water mixed solution comprise cyclic acetal compounds with an odor-causing effect. Aiming at the characteristic that the background organic matters compete strongly in the traditional adsorption process, a certain amount of active carbon is added in two times according to a proportion by utilizing a multi-stage carbon adding method, and most competitive background organic matters can be adsorbed when carbon is added for the first time; because the background organic matters are difficult to desorb and the adsorbed background organic matters are difficult to return to the water body, the adsorption efficiency of the micro-pollutants can be better when the carbon is thrown for the second time; competitive background organic matters can be directionally enriched on part of the activated carbon, so that the adsorption and removal of the micro-pollutants on the rest of the activated carbon are facilitated, and the adsorption effect of the micro-pollutants is improved compared with a single adding mode; particularly, the adsorption and removal ability of the cyclic acetal compound is higher. The method provided by the invention can directionally enrich competitive background organic matters, better utilize the adsorption capacity of the activated carbon in the process of adsorbing and removing the micropollutants, and greatly reduce the operating cost of the activated carbon process. The method disclosed by the invention is suitable for different types of activated carbon and has a wide application range; and the application objects are various, and the method is particularly suitable for natural water and urban sewage.
Specifically, the initial concentration c of the micropollutant-water mixture 0 =100~800ng/L。
Specifically, the activated carbon includes mesoporous activated carbon or microporous activated carbon.
Specifically, in the activated carbon multi-stage adding process, the adding frequency N =2.
Specifically, in the multistage adding process of the activated carbon, the adding amount of the activated carbon for the second time is not less than that of the activated carbon for the first time.
Specifically, in the multistage adding process of the activated carbon, the mass ratio of the first activated carbon to the second activated carbon is 1; more preferably, the mass ratio of the first activated carbon to the second activated carbon is 1.
Specifically, the method for calculating the adding amount of the activated carbon comprises the following steps,
collecting water subjected to activated carbon adding adsorption treatment twice, measuring the content of micro-pollutants, calculating the adsorption capacity of the activated carbon and drawing an adsorption isotherm;
adopting Freundlich model to fit adsorption isotherm and determining K F And the value of 1/n;
according to K F And the value of 1/n and the set adsorption target removal rate.
Specifically, the cyclic acetal compound includes 2-isobutyl-4-methyl-1, 3-dioxolane, 2-isopropyl-5, 5-dimethyl-1, 3-dioxane, or 2-n-butyl-4-methyl-1, 3-dioxolane.
Further, a method for enhancing the removal of micropollutants in water comprises the following specific steps:
1) Adding a micropollutant to water to prepare a micropollutant-water mixed solution;
2) Dividing activated carbon to be added into two parts by weight of D A And D B ；
3) Taking the micro-pollutant-water mixed solution, and adding activated carbon for the first time, wherein the adding amount is D A ；
4) After the adsorption treatment of the activated carbon is finished, the activated carbon is added for the second time, and the adding amount is D B ；
5) After the second activated carbon adsorption treatment is finished, filtering, removing the added activated carbon, and collecting filtrate to obtain second-stage adsorption water; then determining the content of the micro-pollutants in the second stage of the adsorption water as c e ；
6) And (3) calculating and determining the adsorption capacity of the micropollutants on the activated carbon as follows:
and according to the calculated q e And c e Drawing an adsorption isotherm;
7) Adsorption isotherms were fitted using the Freundlich model:
determining K therein F And 1/n value according to K F And 1/n, further calculating the total dosage D of the activated carbon required for adsorbing the micropollutants under a certain removal target (removal rate).
Specifically, the calculation formula of the total activated carbon dosage D is shown in formula (1):
The invention also discloses application of the method for strengthening removal of the micropollutants in water in adsorption removal of the 2-isobutyl-4-methyl-1, 3-dioxolane and/or 2-isopropyl-5, 5-dimethyl-1, 3-dioxane and/or 2-n-butyl-4-methyl-1, 3-dioxolane micropollutants in water.
Compared with the prior art, the invention has the following beneficial effects:
aiming at the characteristic of strong competitiveness of background organic matters in the activated carbon adsorption process, the invention provides the activated carbon adsorption process optimization method which can reduce the competition of the background organic matters and improve the removal efficiency of micro pollutants. And (3) adopting a multistage carbon feeding method, feeding a certain amount of activated carbon for multiple times according to a proportion, after the first carbon feeding is finished, adsorbing for a certain time, then feeding the rest activated carbon, and filtering after adsorbing for a certain time. Most competitive background organic matters can be enriched by the first adding, so that the adsorption capacity of the activated carbon can be fully improved when the activated carbon is added for the second time, and the removal efficiency of the micro-pollutants adsorbed by the activated carbon for water treatment is enhanced. The application of the invention can realize the removal of certain micro-pollutants and save the carbon requirement of the activated carbon adsorption process in water treatment. The method has higher practical application value, is easy to operate and saves cost. The method is suitable for different water bodies such as natural water, urban sewage and the like, is suitable for various activated carbons, and can further improve the treatment efficiency of the adsorption process through the optimization of influence factors such as an adding mode and the like.
Therefore, the invention provides the activated carbon multistage feeding method for strengthening removal of the micropollutants in water, and the method can effectively reduce competition of organic matters under the complex water quality background, overcomes the defect of large carbon feeding amount in the traditional single carbon feeding mode, improves the adsorption removal effect of the micropollutants, is not required to be combined with other processes, is convenient to operate and greatly reduces the operation cost of the activated carbon process.
Drawings
FIG. 1 is an adsorption isotherm of micro-pollutants of 2-isobutyl-4-methyl-1, 3 dioxolane by different adding modes of microporous activated carbon;
FIG. 2 is an adsorption isotherm of 2-isobutyl-4-methyl-1, 3 dioxolane micropollutants by different adding modes of mesoporous activated carbon;
FIG. 3 is an adsorption isotherm of micro-pollutants of 2-isobutyl-4-methyl-1, 3 dioxolane with different addition ratios of activated carbon;
FIG. 4 is an adsorption isotherm of micro-pollutants of 2-isopropyl-5, 5-dimethyl-1, 3-dioxane with different modes of adding microporous activated carbon;
FIG. 5 is an adsorption isotherm of 2-isopropyl-5, 5-dimethyl-1, 3-dioxane micropollutant by different adding modes of mesoporous activated carbon;
FIG. 6 is an adsorption isotherm of micro-pollutants of 2-isopropyl-5, 5-dimethyl-1, 3-dioxane at different addition ratios of activated carbon;
FIG. 7 is an adsorption isotherm of microporous activated carbon for 2-n-butyl-4-methyl-1, 3-dioxolane micropollutants by different adding modes;
FIG. 8 is an adsorption isotherm of 2-n-butyl-4-methyl-1, 3-dioxolane micropollutants with different modes of adding mesoporous activated carbon;
FIG. 9 is an adsorption isotherm of micro-pollutants of 2-n-butyl-4-methyl-1, 3-dioxolane with different addition ratios of activated carbon;
FIG. 10 is an SEM image of activated carbon;
FIG. 11 is an SEM image of surface treated activated carbon;
FIG. 12 is the adsorption isotherm of surface treated activated carbon on 2-isopropyl-5, 5-dimethyl-1, 3-dioxane micropollutants.
Detailed Description
The technical solution of the present invention is further described in detail with reference to the following embodiments:
the activated carbon in the invention needs to meet the core index in coal-based activated carbon for drinking water purification plants (CJ/T345-2010). In particular, the specific surface area of the activated carbon>950m 2 (ii)/g; pore volume>0.65mL/g. Wherein, the microporous carbon is activated carbon with the micropore proportion of more than 60 percent, and the mesoporous carbon is activated carbon with the micropore proportion of less than 60 percent.
Specifically, the indexes of the activated carbon used in the examples of the present invention are shown in table 1:
TABLE 1 specific indices of activated carbon
Example 1:
a method for strengthening removal of micro-pollutants in water comprises the following steps of:
1) Adding micropollutants to water at an initial concentration (c) 0 ) The micropollutant-water mixture of (a);
2) Dividing activated carbon to be added into two parts by weight of D A And D B ；
3) Taking the micro-pollutant-water mixed solution, and adding activated carbon for the first time, wherein the adding amount is D A ；
4) After the adsorption treatment of the activated carbon added for the first time is finished, adding the activated carbon for the second time, wherein the adding amount is D B ；
5) After the second active carbon adsorption treatment is finished, filtering, removing the added active carbon, collecting and filteringObtaining second stage adsorption water; then determining the content of the micro-pollutants in the second stage of the adsorption water as c e ；
6) And (3) calculating and determining the adsorption capacity of the micropollutants on the activated carbon as follows:
and according to the calculated q e And c e Drawing an adsorption isotherm;
7) Adsorption isotherms were fitted using Freundlich model:
determining K therein F And 1/n value according to K F And 1/n further calculating the dosage of the activated carbon required for adsorbing the micropollutants under a certain removal target (80 percent removal rate)D 80 The method comprises the following steps:
example 2:
a method for strengthening removal of micro-pollutants in water comprises the following steps:
1) Adding micropollutants to water at an initial concentration (c) 0 ) The micropollutant-water mixture of (a);
2) The weight of the activated carbon to be added is D A +D B Adding all the activated carbon at one time;
3) After the adsorption treatment of the activated carbon is finished, filtering, removing the added activated carbon, collecting filtrate, and determining the content of the micropollutants in the filtrate as c e ；
4) And (3) calculating and determining the adsorption capacity of the micropollutants on the activated carbon as follows:
and according to the calculated q e And c e Drawing an adsorption isotherm;
5) Adsorption isotherms were fitted using the Freundlich model:
determining K therein F And 1/n value according to K F And 1/n further calculating the dosage of the activated carbon required for adsorbing the micropollutants under a certain removal target (80 percent removal rate)D 80 The method comprises the following steps:
example 3:
the procedure was followed according to the experimental parameter set-up listed in table 2, in combination with the method steps of example 1 and example 2:
TABLE 2 Experimental parameters
Note that: the mass ratio of the added active carbon for two times is 1; the active carbon combination is microporous active carbon and microporous active carbon; the micropollutants are 2-isobutyl-4-methyl-1, 3 dioxolane.
As can be seen from the data analysis in Table 1, for 2-isobutyl-4-methyl-1, 3 dioxolane, the total amount of activated carbon required for the multi-stage addition group is significantly lower than that of the single addition group at the removal target of 80%, and the amount of activated carbon can be reduced by about 30%. The experimental result shows that the mode of multistage adding of the activated carbon is adopted, the using amount of the activated carbon can be obviously reduced, the defect of large carbon adding amount of the traditional single carbon adding mode is overcome, the combination with other processes is not needed, the operation is convenient, and the operation cost of the activated carbon process is greatly reduced.
Example 4:
A. research on adsorption and removal effects of activated carbon multi-stage addition method on 2-isobutyl-4-methyl-1, 3 dioxolane (CAS number 18433-93-7) micro-pollutants
1. Influence of activated carbon of different pore size structures
The experimental method comprises the following steps:
the multi-stage addition (two-step addition) method is the same as that in example 1, and the variation is only that the activated carbon used is microporous activated carbon or mesoporous activated carbon.
The single addition (one-step addition) method was the same as in example 2, with the only change being that the activated carbon used was microporous activated carbon or mesoporous activated carbon.
Results and analysis:
the results of the adsorption isotherms for each set of experiments are shown in FIGS. 1-2. From the analysis in the figure, the adsorption capacity of the activated carbon to the 2-isobutyl-4-methyl-1, 3 dioxolane in the multi-stage adding method is obviously better than that of the single adding method, and the adsorption effect of the microporous activated carbon is obviously better than that of the mesoporous activated carbon.
2. Influence of different carbon addition ratios
The experimental method comprises the following steps:
the method of multi-stage addition (two-step addition) is the same as that in example 1, and the variation is only in the mass ratio of the two times of activated carbon addition.
Results and analysis:
the results of adsorption isotherms plotted for each set of experiments are shown in figure 3. From the analysis in the figure, under the condition that the mass ratio of the two times of activated carbon addition is 1.
B. Research on adsorption and removal effects of activated carbon on 2-isopropyl-5, 5-dimethyl-1, 3-dioxane (CAS number 7651-50-5) micro-pollutants by using multistage adding method
The overall exploration method is the same as the item A.
And (4) analyzing results:
1. influence of activated carbon of different pore size structures
The adsorption isotherms were plotted and the results are shown in FIGS. 4-5. As can be seen from the analysis in the figure, the adsorption capacity of the activated carbon on the 2-isopropyl-5, 5-dimethyl-1, 3-dioxane in the multistage adding method is slightly better than that of the single adding method, but the adsorption effect of the microporous activated carbon is not greatly different from that of the mesoporous activated carbon.
2. Influence of different carbon addition ratios
The adsorption isotherms are plotted and the results are shown in FIG. 6. According to the analysis in the figure, under the condition that the mass ratio of the two times of activated carbon addition is 1.
C. Research on adsorption and removal effects of activated carbon on 2-n-butyl-4-methyl-1, 3-dioxolane (CAS number 74094-60-3) micro-pollutants by multistage adding method
The overall exploration method is the same as the item A.
And (4) analyzing results:
1. influence of activated carbon of different pore size structures
The results of the adsorption isotherms are shown in FIGS. 7-8. Analysis in the figure shows that the adsorption capacity of the activated carbon in the multistage adding method on the 2-n-butyl-4-methyl-1, 3-dioxolane is obviously higher than that of the activated carbon in the single adding method, but the adsorption effect of the microporous activated carbon is obviously higher than that of the mesoporous activated carbon.
2. Influence of different charcoal input ratio
The adsorption isotherms are plotted and the results are shown in FIG. 9. According to the analysis in the figure, under the condition that the mass ratio of the two times of activated carbon addition is 1.
In conclusion, compared with the traditional single adding mode, the multistage active carbon adding method for enhancing the removal of the micropollutants in water provided by the invention has the advantages that the adsorption effect on 2-isobutyl-4-methyl-1, 3-dioxolane, 2-isopropyl-5, 5-dimethyl-1, 3-dioxane or 2-n-butyl-4-methyl-1, 3-dioxolane is obviously improved, and particularly the adsorption removal rate enhancement effect on 2-isobutyl-4-methyl-1, 3-dioxolane and 2-n-butyl-4-methyl-1, 3-dioxolane is obvious. Meanwhile, the adsorption effect of the microporous grade activated carbon is obviously better than that of the mesoporous grade activated carbon. And when the mass ratio of the activated carbon added twice is 1. The method provided by the invention reduces the competition of background organic matters in the process of adsorbing the micro pollutants by the activated carbon through step-by-step carbon feeding, improves the removal efficiency of the micro pollutants, fully utilizes the adsorption capacity of the activated carbon and reduces the process operation cost.
Example 5:
a method for strengthening the removal of micropollutants in water, which is different from the method in example 1: the activated carbon is subjected to surface treatment.
Preferably, the surface treatment of activated carbon comprises: the surface-treated active carbon is obtained by performing impregnation modification on the active carbon by adopting 3-chloropropyldimethylchlorosilane and 1, 4-bis (2-hydroxyethyl) piperazine. According to the invention, 1, 4-bis (2-hydroxyethyl) piperazine is adopted to modify the surface of the activated carbon through impregnation treatment, so that the obtained surface-treated activated carbon has a more excellent pore structure, and the adsorption capacity is further improved; the method is applied to removing the micro-pollutants in water, and is carried out by adopting a multi-stage feeding method, so that the adsorption removal effect of the micro-pollutants is obviously improved, and the adsorption effect of the micro-pollutants on 2-isopropyl-5, 5-dimethyl-1, 3-dioxane is particularly enhanced.
The activated carbon surface treatment comprises the following steps:
pretreating, namely cleaning the activated carbon by using deionized water, and drying to obtain pretreated activated carbon;
and (3) adopting 3-chloropropyldimethylchlorosilane and 1, 4-bis (2-hydroxyethyl) piperazine to sequentially perform impregnation treatment on the pretreated activated carbon to obtain the surface-treated activated carbon.
Specifically, the activated carbon surface treatment includes:
pretreating, namely soaking the activated carbon into deionized water after the activated carbon is washed once by the deionized water, ultrasonically washing for 10 to 15min, carrying out suction filtration, and drying at the temperature of 100 to 110 ℃ until the mass is constant to obtain pretreated activated carbon;
mixing tetraethyl orthosilicate, ethanol and water, adding hydrochloric acid with the mass concentration of 8-12% to adjust the pH to 2-3, and promoting the hydrolysis of the tetraethyl orthosilicate for 5-7 h; then adding ammonia water with the mass concentration of 8-12% to adjust the pH value to 9-10 to obtain an aging solution; soaking the pretreated activated carbon in an aging solution in an equal amount, and standing at room temperature for 10 to 12h; then adding equivalent N, N-dimethylformamide, and replacing the N, N-dimethylformamide every 6 hours for 3 to 5 times; then adding 1.5 to 3 times of volume of a solution of 3-chloropropyldimethylchlorosilane/N, N-dimethylformamide with the mass fraction of 25 to 35 percent, soaking for 24 to 48h, and leaching for 3 times by using N, N-dimethylformamide; then adding 1.5 to 3 times of volume of N, N-dimethylformamide solution containing 1, 4-bis (2-hydroxyethyl) piperazine with the mass concentration of 10 to 15, adding sodium hydride, carrying out immersion treatment at 60 ℃ for 10 to 15h, carrying out drip washing on N, N-dimethylformamide for 3 times, and drying at 30 ℃,60 ℃, 90 ℃, 120 ℃ and 150 ℃ for 1 to 2h respectively to obtain the surface-treated activated carbon.
Specifically, the molar ratio of tetraethyl orthosilicate to ethanol to water is 1 to 9 to 11; the molar ratio of sodium hydride to 1, 4-bis (2-hydroxyethyl) piperazine is 2.5 to 3.
In this embodiment, the preparation method of the modified activated carbon specifically includes:
pretreating, namely soaking the activated carbon into deionized water after the activated carbon is washed once by the deionized water, ultrasonically washing for 15min, performing suction filtration, and drying at 105 ℃ until the mass is constant to obtain pretreated activated carbon;
tetraethyl orthosilicate, ethanol and water are taken according to the molar ratio of 1; then adding ammonia water with the mass concentration of 10% to adjust the pH value to 10 to obtain an aging solution; soaking the pretreated activated carbon in the aging solution in an equal amount, and standing at room temperature for 12h; then adding N, N-dimethylformamide with the same amount, and replacing the N, N-dimethylformamide once every 6 hours for 4 times; then adding 2.5 times of volume amount of 31.5 percent by mass of 3-chloropropyldimethylchlorosilane/N, N-dimethylformamide solution, dipping for 24h, and leaching for 3 times by using N, N-dimethylformamide; then, a 2-fold volume of a 1, 4-bis (2-hydroxyethyl) piperazine-containing N, N-dimethylformamide solution having a mass concentration of 10 to 15 was added, sodium hydride (molar ratio to 1, 4-bis (2-hydroxyethyl) piperazine: 2.8) was added, immersion treatment was performed at 60 ℃ for 13h, elution was performed with N, N-dimethylformamide for 3 times, and drying was performed at 30 ℃,60 ℃, 90 ℃, 120 ℃, and 150 ℃ for 2 hours, respectively, to obtain surface-treated activated carbon.
Field emission Scanning Electron Microscope (SEM) characterization
And testing the change of the micro-morphology of the surface of the activated carbon in the modification process by adopting SEM, wherein the testing multiplying power is 50.0K.
The above tests were carried out on the activated carbon, the surface-treated activated carbon prepared in example 5, and the results are shown in FIGS. 10 to 11. From the analysis of the figure, compared with the SEM scanning result of the activated carbon (fig. 10), the SEM image (fig. 11) of the modified activated carbon prepared in example 5 has richer surface pore structure and more tiny pores, which indicates that the reaction between 3-chloropropyldimethylchlorosilane and 1, 4-bis (2-hydroxyethyl) piperazine mainly occurs on the surface during the surface modification of the activated carbon, forming a more complex spatial structure, and bringing beneficial effects on the surface morphology and properties of the sample, thereby improving the adsorption performance of the surface-treated activated carbon.
Pore parameter characterization
N on a specific surface area and porosity analyzer (ASAP 2420, micromeritics, USA) 2 And (3) performing adsorption-desorption test, wherein the degassing temperature is 300 ℃, and the specific surface area and the pore size distribution of the sample are tested and analyzed.
The above tests were carried out on activated carbon, surface treated activated carbon prepared in example 5, and the results are shown in table 3:
table 3 pore structure test results
| Sample (I) | Average pore diameter (nm) | Micropore volume (cm) 3 /g） | Specific surface area (m) 2 /g） |
| Example 5 | 1.81 | 0.43 | 1095 |
| Activated carbon | 2.07 | 0.44 | 1003 |
As can be seen from the analysis in table 3, the surface-treated activated carbon prepared in example 5 has a significantly reduced average pore diameter, an increased micropore volume, comparable to activated carbon, and a certain increase in specific surface area, compared to activated carbon, and it is likely that the reaction of 3-chloropropyldimethylchlorosilane with 1, 4-bis (2-hydroxyethyl) piperazine occurs mainly at the surface, not completely blocking the pore diameter, but rather, filling a portion of the pores is converted into more minute pores; and 1, 4-bis (2-hydroxyethyl) piperazine is added and compounded with other components to form a porous space structure on the surface, so that new micropores are formed, the loss of part of specific surface area is compensated, and the formed micropores have the same volume as blocked micropores.
Example 6:
exploration of adsorption property of surface-treated activated carbon
1. Research on adsorption removal effect of 2-isobutyl-4-methyl-1, 3 dioxolane micro-pollutants
The experimental method comprises the following steps: the multi-stage addition (two-step addition) method was the same as in example 1, except that the activated carbon used was the surface-treated activated carbon prepared in example 5.
The test results are shown in table 4:
table 4 adsorption performance test results
| Sample (I) | D 80 （mg/L） |
| Example 5 | 6.45 |
| Example 1 | 10.69 |
From the data analysis in table 4, it can be seen that, when the modified activated carbon prepared in example 5 of the present invention is used to adsorb micro-pollutants in water, for 2-isobutyl-4-methyl-1, 3 dioxolane, the total amount of the activated carbon required for the adsorption treatment is significantly reduced, and the amount of the activated carbon used can be reduced by about 40% under the removal target of 80%; the surface of the activated carbon is chemically modified by 1, 4-bis (2-hydroxyethyl) piperazine and is compounded with other components for use, so that the adsorption performance of the activated carbon after surface treatment can be effectively improved, and the adsorption removal effect of the activated carbon on micro-pollutants in water is enhanced.
2. Research on the adsorption and removal effects of 2-isopropyl-5, 5-dimethyl-1, 3-dioxane micropollutants
The experimental method comprises the following steps:
the multi-stage addition (two-step addition) method is the same as that in example 5, and the variation is only that the micro-pollutant in water is 2-isopropyl-5, 5-dimethyl-1, 3-dioxane.
Results and analysis:
the results of the adsorption isotherm plotting in the experiment are shown in FIG. 12. As can be seen from the analysis of the figure, the adsorption capacity of the activated carbon surface treated by the method is obviously better than that of the activated carbon surface treated by the method before treatment, and the method shows that the activated carbon surface chemically modified by 1, 4-bis (2-hydroxyethyl) piperazine and compounded with other components can effectively improve the adsorption capacity of the activated carbon surface treated by the method on the 2-isopropyl-5, 5-dimethyl-1, 3-dioxane.
Conventional techniques in the above embodiments are known to those skilled in the art, and thus will not be described in detail herein.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (9)
1. A method for enhancing the removal of micropollutants from water, comprising: adsorbing the micro-pollutant-water mixed solution by adopting a mode of multistage addition of activated carbon;
in the multi-stage active carbon adding process, the adding frequency N is more than or equal to 2;
in the method, the total adding amount of the activated carbon is obtained by calculation according to the adsorption capacity of the activated carbon and the target removal rate of the micropollutants; the total adding amount of the active carbon is calculated by the following steps,
collecting water subjected to activated carbon adding adsorption treatment twice, measuring the content of micro-pollutants, calculating the adsorption capacity of the activated carbon and drawing an adsorption isotherm;
adopting Freundlich model to fit adsorption isotherm and determining K F And the value of 1/n;
according to K F And 1/n value, and the set adsorption target removal rate to calculate the total adding amount of the activated carbon;
the activated carbon is subjected to surface treatment before being added, and the method specifically comprises the following steps:
pretreating, namely cleaning the activated carbon by using deionized water, and drying to obtain pretreated activated carbon;
sequentially carrying out impregnation treatment on the pretreated active carbon by adopting 3-chloropropyldimethylchlorosilane and 1, 4-bis (2-hydroxyethyl) piperazine to obtain surface-treated active carbon;
the micropollutants in the micropollutants-water mixed liquor comprise cyclic acetal compounds.
2. The method of enhancing removal of micropollutants from water of claim 1, wherein: initial concentration c of the micropollutant-water mixture 0 =100~800ng/L。
3. The method of claim 1, wherein the method further comprises the steps of: the activated carbon comprises mesoporous activated carbon or microporous activated carbon.
4. The method of claim 1, wherein the method further comprises the steps of: the cyclic acetal compound comprises 2-isobutyl-4-methyl-1, 3-dioxolane or 2-isopropyl-5, 5-dimethyl-1, 3-dioxane or 2-n-butyl-4-methyl-1, 3-dioxolane.
5. The method for enhancing removal of micropollutants from water of claim 1, 2, 3 or 4, wherein: and in the activated carbon multistage adding process, the adding frequency N =2.
6. The method of claim 5, wherein the method further comprises the step of: in the multistage active carbon adding process, the adding amount of the active carbon for the second time is not less than that of the active carbon for the first time.
7. The method of claim 6, wherein the method further comprises the steps of: in the multistage adding process of the activated carbon, the mass ratio of the first activated carbon to the second activated carbon is 1.
8. Use of the method of enhancing removal of micropollutants in water according to claim 1 for adsorptive removal of 2-isobutyl-4-methyl-1, 3 dioxolane and/or 2-isopropyl-5, 5-dimethyl-1, 3-dioxane micropollutants in water.
9. Use of the method of enhancing removal of micropollutants in water according to claim 1 for adsorptive removal of 2-isopropyl-5, 5-dimethyl-1, 3-dioxane and/or 2-n-butyl-4-methyl-1, 3-dioxolane micropollutants in water.
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