CN111266081B - Preparation method and application of ferric oxyhydroxide modified vermiculite composite adsorption material for removing Mn from underground water - Google Patents

Preparation method and application of ferric oxyhydroxide modified vermiculite composite adsorption material for removing Mn from underground water Download PDF

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CN111266081B
CN111266081B CN202010200093.8A CN202010200093A CN111266081B CN 111266081 B CN111266081 B CN 111266081B CN 202010200093 A CN202010200093 A CN 202010200093A CN 111266081 B CN111266081 B CN 111266081B
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吴慧英
粘雅馨
黄博凡
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Hunan University
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Abstract

The invention relates to a preparation method and application of a hydroxyl ferric oxide modified vermiculite composite adsorption material for removing Mn from underground water, wherein vermiculite is washed for multiple times, then is subjected to acid treatment, then is subjected to solid-liquid separation, and then is washed until the washing liquid is neutral, and then is dried for later use; putting vermiculite into a water-soluble ferric salt solution, and ultrasonically shaking for 30-60min to obtain a mixed solution; dropwise adding alkali liquor into the mixed solution while stirring until the pH value of the mixed solution is 10-12, then continuously stirring for 30-120min, then performing constant-temperature aging, cooling, and performing solid-liquid separation to obtain a composite adsorption material primary product; and (3) washing, drying and cooling the initial product of the composite adsorbing material to obtain the ferric hydroxide modified vermiculite composite adsorbing material. The composite adsorbing material disclosed by the invention is good in stability and easy to recover, can simultaneously exert the activity of strengthening, catalyzing and adsorbing manganese ions by using the iron oxyhydroxide and the excellent adsorption performance of vermiculite, has higher adsorption capacity compared with single vermiculite, and has the Mn adsorption capacity of 2.94mg/g under low concentration.

Description

Preparation method and application of ferric oxyhydroxide modified vermiculite composite adsorption material for removing Mn from underground water
Technical Field
The invention relates to a preparation method and application of a ferric hydroxide modified vermiculite composite adsorption material, in particular to a preparation method and application of a ferric hydroxide modified vermiculite composite adsorption material for adsorbing and removing Mn (II) in manganese-containing groundwater, and belongs to the field of drinking water treatment.
Background
China has abundant underground water resources, but in many areas, the manganese content of underground water sources exceeds the standard due to hydrogeology and other reasons, and the underground water is called manganese-containing underground water. If the underground water with the excessive manganese content is drunk for a long time, chronic poisoning is easily caused, inappetence, vomit, diarrhea, gastrointestinal disorder and abnormal stool are caused, even paralysis agitans occur, the nervous system of a person is seriously harmed, the inner wall of an artery and cardiac muscle are damaged, atheromatous plaque is formed, and coronary artery stenosis to coronary heart disease and the like are caused. Meanwhile, the excessive manganese content can cause the underground water to have bad smell, and can be gradually deposited on sanitary wares, washing clothes and the inner wall of a pipeline to generate manganese spots, and when the water flow speed and the water flow direction in the pipeline are changed, the phenomenon of 'black water' can be caused by the deposition, and the like, so that people cannot tolerate the phenomenon. The limit value of the manganese content is 0.1mg/L as specified in the sanitary Standard for Drinking Water (GB5749-2006) in China. Therefore, groundwater with an excessive manganese content must be purified before drinking. The method effectively removes the overproof manganese ions in the underground water, and is the key for guaranteeing the water consumption of residents.
At present, the common methods for treating the manganese-containing underground water in China are mainly a natural oxidation method, a contact oxidation method and a biological oxidation method. The methods are mainly used for large-scale treatment processes of centralized domestic drinking water treatment plants, and the process has higher requirements on the pH value of raw water and the process operation level. However, China still has no centralized water supply facility in some rural areas, and villagers can directly pump underground water or use small household water purifiers to treat the water to be used as drinking water. The small household water purifiers on the market at present have no treatment function aiming at the excessive manganese content of underground water. Therefore, when the manganese content of the underground water exceeds the standard, the drinking water in rural areas in the places is difficult to be safely guaranteed.
Disclosure of Invention
Aiming at the defects of the prior art, one of the purposes of the invention is to provide a preparation method of an iron oxyhydroxide modified vermiculite composite adsorption material, so as to improve the adsorption capacity and removal rate of Mn (II) in groundwater; the second purpose of the invention is to provide the application of the iron oxyhydroxide modified vermiculite composite adsorption material in the removal of Mn (II) in manganese-containing underground water, so that the manganese-containing underground water after treatment reaches the limit regulation of Mn (II) in sanitary Standard for Drinking Water (GB 5749-2006).
In order to solve the technical problems, the technical scheme of the invention is as follows:
a preparation method of a hydroxyl ferric oxide modified vermiculite composite adsorption material for removing Mn from underground water comprises the following steps:
s1, washing vermiculite for multiple times, mixing the vermiculite with a dilute acid solution, stirring for reaction for 2-4 hours, carrying out solid-liquid separation, washing the vermiculite subjected to acid treatment until the washing liquid is neutral, and drying for later use;
s2, placing the vermiculite subjected to the S1 treatment in a water-soluble ferric salt solution, and performing ultrasonic oscillation for 30-60min to obtain a mixed solution;
s3, slowly adding alkali liquor dropwise into the mixed liquor obtained in the step S2 while stirring until the pH value of the mixed liquor is 10-12, then continuously stirring for 30-120min, then performing constant-temperature aging for 24-60h, cooling, and performing solid-liquid separation to obtain a composite adsorption material initial product;
and S4, washing the composite adsorbing material primary product obtained in the S3 for multiple times, drying and cooling to obtain the iron oxyhydroxide modified vermiculite composite adsorbing material.
Further, in S1, the pH of the dilute acid solution is 1 to 3, and the mass-to-volume ratio of the vermiculite to the dilute acid solution is 1 g: 10-30mL, preferably 1 g: 20 mL; further, the acid is hydrochloric acid and/or sulfuric acid.
Further, in S1 and/or S4, the drying mode is constant temperature drying, and preferably, the drying temperature is 80-105 ℃. Optionally, drying is performed in an incubator.
Preferably, in S1, the vermiculite is natural vermiculite.
Further, in S1, after drying, screening by 40-mesh and 60-mesh sieves to obtain vermiculite with the particle size of 40-60 meshes for later use.
In general, in S1, the neutral PH can be understood as 6.0 to 7.5, and further 6.5 to 7.5.
Further, in S2, the water-soluble ferric salt is ferric nitrate and/or ferric sulfate, preferably ferric nitrate.
Further, in S2, Fe in the water-soluble ferric salt solution 3+ The concentration of (b) is 0.1-1mol/L, preferably 0.25 mol/L; the mass ratio of the water-soluble ferric salt to the vermiculite is 1:1-4:1, and preferably 2: 1.
Further, in S2, the ultrasonic power is controlled to be 300-600W during the ultrasonic oscillation, optionally, the ultrasonic oscillation is performed at normal temperature, and further, the temperature of the water-soluble ferric salt solution is 20-30 ℃ during the ultrasonic oscillation.
Further, in S3, the temperature is controlled to be 60-200 ℃, preferably 60-100 ℃, and further more preferably 70-90 ℃ during constant temperature aging. The applicant repeatedly researches and discovers that when the aging temperature is controlled to be 60-100 ℃, the removal effect of the obtained composite adsorption material on manganese in underground water is usually particularly good. This is because in this temperature range, the ferric iron exists mainly in FeOOH form, and Mn (II) and FeOOH undergo ionic complexation reaction, so that Mn (II) and oxygen in FeOOH undergo hydrogen bonding bridging complexation to form FeOO-Mn + Or (FeOO) 2 The complex structure of Mn, thereby achieving the effects of strengthening adsorption and efficiently removing Mn (II).
Further, in S3, the alkali liquor is a sodium hydroxide solution, and the concentration is 1-3 mol/L.
Further, in S3, the stirring is continued for 30-60 min. Optionally, the temperature of the mixture is controlled to be 20-30 ℃ during the period of continuing stirring.
Based on the same invention concept, the invention also provides the application of the ferric oxyhydroxide modified vermiculite composite adsorption material prepared by the preparation method in removing manganese in manganese-containing underground water.
Generally, the manganese refers to divalent manganese.
Further, mixing the manganese-containing underground water to be treated with the iron oxyhydroxide modified vermiculite composite adsorption material, and oscillating at constant temperature; wherein the mass volume ratio of the ferric hydroxide modified vermiculite composite adsorption material to the manganese-containing underground water is 0.4-4 g: 1000 mL; further, Mn in the manganese-containing groundwater 2+ The initial concentration of (A) is 0.5-3mg/L, and the pH value is 3-9.
Further, shaking at constant temperature for 10-180 min.
The iron oxyhydroxide modified vermiculite composite adsorption material developed by the invention is particularly suitable for treating manganese-containing underground drinking water in villages and towns.
The composite adsorption material has high-efficiency adsorption performance on low-concentration manganese ions in a water body, an adsorption column can be constructed by taking the adsorption material as a core, and the adsorption column is embedded into a small household water purifier to replace an active carbon column or a PP cotton filter column in the small household water purifier, and can be developed into a small household water purifier aiming at removing manganese from underground water so as to solve the problem that the manganese content of the drinking underground water in rural areas exceeds the standard. The composite adsorption material is used for treating manganese-containing underground water, the manganese content of treated water reaches not more than 0.1mg/L specified in sanitary Standard for Drinking Water (GB5749-2006), and the composite adsorption material is economic, efficient, safe and environment-friendly, and has good practical significance for drinking water reformation in rural areas and rural drinking water safety guarantee. In addition, the adsorption method is easy to operate, efficient, rapid and free of secondary pollution except for manganese, and has wide application prospects.
Vermiculite is selected as a good adsorbent in the present invention. The vermiculite is treated by dilute acid, so that surface impurities can be removed, and subsequent modification is facilitated; mixing the pretreated vermiculite with a water-soluble ferric salt solution, slowly adding alkali liquor dropwise to adjust the pH value to 10-12, continuously reacting for a certain time, and finally carrying out constant-temperature aging reaction at a high temperature of 60-100 ℃ for 24-60 hours to form a ferric oxyhydroxide load which can be firmly adhered to the vermiculite. Iron oxyhydroxide has enhanced catalytic adsorption activity for mn (ii), but iron oxyhydroxide alone has fine particles and is difficult to separate from water. According to the invention, the iron oxyhydroxide is loaded on the vermiculite, so that on one hand, the simple separation of the iron oxyhydroxide and the aqueous solution can be realized, and the operability of the iron oxyhydroxide in practical water treatment application is enhanced; on the other hand, the iron oxyhydroxide is newly generated in the hydrolysis process, so the particle size of the iron oxyhydroxide is small, the iron oxyhydroxide belongs to a nanometer level, the specific surface area is large, the binding capacity with a layer structure of vermiculite is large, and the iron oxyhydroxide is not easy to fall off, so the stability of the adsorption material is good, the iron ion falling and secondary pollution are avoided, the reinforced catalytic adsorption activity of the iron oxyhydroxide and the excellent adsorption performance of the vermiculite can be well exerted, and the efficient removal of Mn (II) is realized. The composite adsorbing material has better effect of removing Mn (II) than vermiculite alone. After the manganese-containing underground water is treated by the composite adsorbing material developed by the research, the manganese content in the treated effluent is lower than 0.1mg/L, and the manganese-containing underground water meets the requirement on manganese ions in sanitary Standard for Drinking Water GB 5749-2006.
Compared with the prior art, the iron oxyhydroxide modified vermiculite composite adsorption material prepared by the invention and the application thereof have the following advantages:
(1) the invention provides a preparation method of an iron oxyhydroxide modified vermiculite composite adsorption material, which combines the reinforced catalytic adsorption activity of the iron oxyhydroxide on Mn (II) with vermiculite with excellent adsorption performance, realizes the effect of efficiently removing Mn (II) in underground water by a simple adsorption mode, and achieves the manganese content in treated water lower than 0.1mg/L to meet the requirement of sanitary Standard for Drinking Water GB5749-2006 on the manganese content. The complex process of manganese removal by the existing oxidation method is avoided. The composite adsorption material prepared by the invention is used for constructing an adsorption column and is combined into a small household water purifier, so that the manganese removal function of the household water purifier can be enhanced, a new way is provided for treating drinking underground water in manganese-containing underground water, particularly rural areas, and the composite adsorption material has important significance for guaranteeing the safety of drinking underground water in rural areas.
(2) Many researches on the modified material of the iron oxyhydroxide are carried out, and a small amount of research reports on the adoption of vermiculite for removing manganese. However, the research that the ferric hydroxide is loaded on the vermiculite to construct the composite adsorption material and the trace over-standard manganese in the drinking water is removed by adopting an adsorption method is not reported, and the problem that the ferric hydroxide is difficult to separate from the aqueous solution after being used by adopting the scheme of the invention is not reported in the prior art. The preparation method adopts a precipitation method, forms FeOOH (FeOOH) by controlling parameters such as the pH value, the aging temperature and the like of the alkali-adding reaction, loads the FeOOH on the vermiculite, and greatly improves the adsorption performance of the vermiculite by means of the enhanced catalytic adsorption activity of the FeOOH. The adsorption capacity and removal efficiency of the composite adsorption material to manganese ions are obviously superior to those of the traditional vermiculite adsorption material, and the adsorption capacity of Mn (II) reaches 2.94mg/g under low concentration (the manganese content is 0.5-3 mg/L).
(3) The preparation method of the invention abandons the traditional direct dipping method, and utilizes ultrasonic dipping oscillation to ensure that the ferric salt and the vermiculite are dispersed uniformly and the loading efficiency is higher;
(4) after vermiculite and water-soluble ferric salt solution are subjected to ultrasonic dipping and oscillation, alkaline solution is slowly dripped under the stirring condition, the final pH value of the reaction is controlled to be 10-12, and finally, the aging reaction is carried out at the temperature of 60-100 ℃ for 24-60 hours, so that the formed load is ferric hydroxide which has excellent reinforced catalytic adsorption activity and can be stably and firmly loaded on the vermiculite, and the obtained composite adsorption material has good stability and does not generate secondary pollution;
(5) the composite adsorbing material disclosed by the invention is low in raw material cost, simple in method and easy to operate.
Drawings
FIG. 1 is a Scanning Electron Micrograph (SEM) of vermiculite of example 1: (a)200 times, (b)50k times;
FIG. 2 is a Scanning Electron Micrograph (SEM) of the iron oxyhydroxide-modified vermiculite composite of example 1: (c)200 times, (d)50k times;
FIG. 3 shows an adsorbent N 2 An adsorption desorption isotherm diagram wherein (a) is vermiculite and (b) is the iron oxyhydroxide-modified vermiculite composite of example 1;
FIG. 4 is a plot of pore size versus pore volume fraction of an adsorbent material, (a) vermiculite, (b) iron oxyhydroxide-modified vermiculite composite of example 1;
FIG. 5 is a graph showing the Mn (II) removal rate of water with time under the adsorption of different adsorbing materials;
FIG. 6 is a graph showing the effect of pH change of a solution on the removal efficiency of Mn (II) from a vermiculite/iron oxyhydroxide modified vermiculite composite;
FIG. 7 is a graph showing the effect of initial concentration of manganese in water on the removal efficiency of Mn (II) from a vermiculite/iron oxyhydroxide-modified vermiculite composite.
Detailed Description
In order to make the preparation method and application of the present invention easy to understand, the present invention will be further described with reference to the specific examples and the accompanying drawings, but the embodiments of the present invention are not limited thereto.
In the present embodiment, the adsorption removal rate of the mn (ii) by the adsorbent material is calculated by the following formula:
(initial Mn (II) concentration-residual Mn (II) concentration after reaction) 100%/initial Mn (II) concentration
The adsorption capacity of the adsorption material for Mn (II) is calculated according to the following formula:
(initial Mn (II) concentration-residual Mn (II) concentration after reaction) solution volume/adsorbent dosage
Example 1
In this embodiment, the preparation method of the iron oxyhydroxide-modified vermiculite composite adsorption material is as follows:
the method comprises the following steps: weighing 10g of natural vermiculite, washing the natural vermiculite with deionized water for 10-15 times, adding the natural vermiculite into 200ml of 0.01mol/L dilute hydrochloric acid solution, stirring and reacting for 2 hours, washing the washed vermiculite with deionized water until the washing liquid is nearly neutral (the pH value is 6.5-7.5), putting the washed vermiculite into a thermostat at 105 ℃ to dry until the weight is constant, and sieving the vermiculite with 40-60 meshes to obtain pretreated vermiculite with the particle size of 40-60 meshes;
step two: 6g of pretreated vermiculite with 200ml of 0.25mol/L Fe (NO) 3 ) 3 Stirring and mixing the solution, soaking and oscillating for 30min by using 400W ultrasonic waves at normal temperature, adjusting the pH value to 12 by using an alkaline solution, stirring and reacting for 60min, aging for 48 hours in a constant temperature box at 60 ℃, cooling, filtering and separating to obtain a primary product of the composite adsorbing material. Washing the primary product with deionized water until the primary product is nearly neutral, and putting the primary product into a 105 ℃ thermostat to dry the primary product to constant weight to obtain the iron oxyhydroxide modified vermiculite composite adsorption material;
fig. 1 is a Scanning Electron Microscope (SEM) image of vermiculite, and fig. 2 is a SEM image of iron oxyhydroxide-modified vermiculite composite material after the first and second steps. As can be seen, the vermiculite structure is a layered structure, the surface is relatively smooth, and a small amount of blocky and flaky impurity particles are contained around the vermiculite structure; the vermiculite modified by the ferric oxyhydroxide has more obvious layered structure and increased surface roughness, is loaded with a large amount of nano ferric oxyhydroxide particles which are distributed dispersedly, disorderly and partially overlapped, has the diameter of between 10 and 150nm, has no obvious agglomeration phenomenon, increases the contact area with adsorbate and is more beneficial to adsorption.
Fig. 3 is a nitrogen adsorption isotherm of vermiculite (a)/iron oxyhydroxide-modified vermiculite (b). The analytical test was carried out on a model JW-BK200C specific surface area analyzerThe sample is degassed at 120 ℃ for about 8h and then subjected to N under 77K conditions 2 Isothermal adsorption experiments. As can be seen from FIG. 3, the trend of the change of the nitrogen adsorption curve of the vermiculite before and after the modification of the iron oxyhydroxide is basically consistent, and is in P/P 0 When the pressure is smaller, the adsorption quantity slowly rises along with the increase of the relative pressure; when P/P is present 0 When the concentration is between 0.4 and 1.0, the rising rate of the vermiculite nitrogen adsorption quantity before and after modification is gradually increased, and the trailing and lagging loop phenomenon appears at a higher partial pressure position (the phenomenon is caused by two factors of multi-layer adsorption of pore walls and coagulation in pores during adsorption, and the desorption is caused by capillary vessel coagulation only). However, the gas adsorption amount before and after vermiculite modification is greatly changed. The gas adsorption amount of iron oxyhydroxide-modified vermiculite (ordinate in fig. 3 (b)) is greatly increased as compared with the gas adsorption amount of vermiculite (ordinate in fig. 3 (a)). The adsorption capacity of the vermiculite is greatly improved after the vermiculite is modified by the ferric hydroxide.
The pore size and pore volume integral distribution diagram 4 and the BET surface area characteristic parameter of the vermiculite/iron oxyhydroxide modified vermiculite can be respectively obtained according to the nitrogen adsorption isotherm of figure 3 and are shown in Table 1.
As can be seen from Table 1, the specific surface area and the total pore volume of the vermiculite are obviously increased and the average pore diameter is reduced after the vermiculite is modified by the ferric hydroxide. These changes are extremely beneficial for improving the adsorption reaction sites and adsorption capacity of the iron oxyhydroxide modified vermiculite. The reason is that the ferric oxyhydroxide loaded on the surface of the vermiculite is newly generated in the hydrolysis process, the particle size is small and belongs to the nanometer level, and the process of loading the ferric oxyhydroxide on the vermiculite is gradually formed by slowly dripping alkali liquor under the condition of continuous stirring and continuously stirring for reacting for a certain time, so that the ferric oxyhydroxide can be uniformly loaded on the vermiculite, is relatively dispersed in distribution and has no obvious agglomeration phenomenon (as shown in figure 2), and the specific surface area and the total pore volume are obviously increased; the nanometer iron oxyhydroxide has small pore diameter and can be loaded on the surface or in the pores of the vermiculite, so that the average pore diameter of the iron oxyhydroxide modified vermiculite composite material is reduced.
It can be seen from the pore size distribution diagram of fig. 4 that the pore sizes before and after modification of vermiculite are mainly 2-50nm, and peak values appear at 34.33nm, but the pore volume of the iron oxyhydroxide modified vermiculite is increased more in the range of pore size of 2-25nm, which is probably because the iron oxyhydroxide is embedded into the inner wall of the vermiculite pore, so that part of the larger pore size is reduced, and the micropore volume is increased.
TABLE 1 BET surface characteristics before and after vermiculite modification
Figure BDA0002419061950000061
Example 2
The preparation method of the iron oxyhydroxide-modified vermiculite adsorption material is the same as the first step and the second step of the example 1.
Step three: weighing the obtained composite adsorbing material and unmodified vermiculite by 0.1000g (+ -0.0005 g) respectively, putting the materials into 250mL conical flasks with stoppers, adding 100mL of water sample with initial concentration of 3mg/L Mn (II), putting the water sample into a constant temperature oscillator, fully oscillating at 25 ℃ (150r/min), and stopping oscillating after adsorbing for 180 min;
step four: and (3) filtering the supernatant after shaking in the third step through a 0.45-micron microfiltration membrane, and measuring the concentration of the residual Mn (II) in the filtrate by using an Shimadzu AA-7000 atomic absorption spectrophotometer. The results show that: for a water sample with the initial concentration of 3mg/L Mn (II), the adsorption capacity of vermiculite for adsorbing Mn (II) is 1.80mg/g, and the adsorption capacity of the iron oxyhydroxide modified vermiculite composite material for adsorbing Mn (II) is 2.94mg/g, which shows that the adsorption removal performance of the iron oxyhydroxide modified vermiculite composite material for Mn (II) is greatly improved compared with that of vermiculite, and the improvement amplitude is more than 63%.
Example 3
The preparation method of the iron oxyhydroxide-modified vermiculite adsorption material is the same as the first step and the second step of the example 1.
Step three: weighing 0.1000g (+ -0.0005 g) of each of the obtained composite adsorbing material and unmodified vermiculite, respectively putting the materials into 250mL conical flasks with stoppers, adding 100mL of water sample with initial concentration of 3mg/L Mn (II), putting the water sample into a constant temperature oscillator, fully oscillating (150r/min) at the temperature of 25 ℃, and stopping oscillating after adsorbing for 180 min;
step four: measuring the supernatant after the third oscillation step and passing through a 0.45 mu m microporous filter membrane when the adsorption time is 10min, 30min, 60min, 120min and 180min respectively, and measuring the concentration of the residual Mn (II) in the filtrate by using an Shimadzu AA-7000 atomic absorption spectrophotometer to obtain a curve of the change relationship of the concentration of Mn (II) in the solution with time when the vermiculite and the iron oxyhydroxide modified vermiculite composite material adsorb Mn (II) in water. The result is shown in FIG. 5. The results of fig. 5 show that: under the same conditions, the adsorption removal rate of the ferric hydroxide modified vermiculite adsorption material on Mn (II) is improved by more than 25 percent compared with that of vermiculite, the adsorption balance is achieved when the adsorption time is 2hr, the adsorption removal rate of Mn (II) reaches 97.9 percent, the concentration of residual Mn (II) in the treated water is 0.06mg/L, and the requirement of sanitary standard for domestic drinking water GB5749-2006 on the manganese content being lower than 0.1mg/L is met. The adsorption removal rate of vermiculite to Mn (II) is only 72%, and the concentration of residual Mn (II) in the water after adsorption treatment is 0.84mg/L and is far more than 0.1mg/L.
Example 4
The preparation method of the iron oxyhydroxide-modified vermiculite adsorption material is the same as the first step and the second step of the example 1.
Step three: weighing 0.1000g (+ -0.0005 g) of each of the obtained composite adsorbing material and unmodified vermiculite, respectively putting the materials into 250mL conical flasks with stoppers, adding 100mL of water sample with initial concentration of 3mg/L Mn (II), respectively adjusting the pH values of the water samples to be 4, 5, 6, 7, 8 and 9, putting the water samples into a constant-temperature oscillator, fully oscillating (150r/min) at the temperature of 25 ℃, and stopping oscillating after adsorbing for 180 min;
step four: measuring the supernatant after shaking in the third step, passing the supernatant through a 0.45-micron microfiltration membrane, and measuring the concentration of the residual Mn (II) in the filtrate by using an Shimadzu AA-7000 atomic absorption spectrophotometer to obtain a graph showing the influence relationship of the change of the pH value of the solution on the adsorption and removal efficiency of Mn (II) in the water by the vermiculite and ferric hydroxide modified vermiculite composite material, wherein the graph is shown in FIG. 6.
FIG. 6 shows that when the pH of raw water is greater than or equal to 6, the ferric hydroxide modified vermiculite adsorption material has a good adsorption effect on Mn (II), the removal rate is more than 98%, the removal effect is stable, and the raw water is not affected by the pH. The PH of groundwater is usually above 6.0 and therefore no adjustment of the PH of raw water is necessary with the adsorbent material of the invention. The existing manganese removal process by catalytic oxidation requires that the PH of raw water is above 7.0 to have good manganese removal effect. Leading to groundwater demanganization processes that require attempts to raise the PH of the raw water. The effect of adsorbing and removing Mn (II) by unmodified vermiculite is greatly influenced by the pH value, when the pH value is less than or equal to 8, the removal rate of Mn (II) is not high, only when the pH value is more than or equal to 9, the removal rate of Mn (II) can reach 95%, but the treated water still cannot meet the requirement, and the effect of adsorbing and removing Mn (II) by the vermiculite before modification under the above conditions is lower than that after modification.
Example 5
The preparation method of the iron oxyhydroxide-modified vermiculite adsorption material is the same as the first step and the second step of the example 1.
Step three: weighing 0.1000g (+ -0.0005 g) of each of the obtained composite adsorbing material and unmodified vermiculite, respectively putting the materials into 250mL conical flasks with stoppers, respectively adding 100mL of water samples with Mn (II) initial concentration of 0.5mg/L, 1.0mg/L, 1.5mg/L, 2mg/L and 3mg/L into the materials, putting the materials into a constant temperature oscillator, fully oscillating the materials at the temperature of 25 ℃ (150r/min), and stopping oscillating the materials after adsorbing the materials for 180 min;
step four: measuring the supernatant after shaking in the third step, passing the supernatant through a 0.45 mu m microfiltration membrane, and measuring the concentration of the residual Mn (II) in the filtrate by using an Shimadzu AA-7000 atomic absorption spectrophotometer to obtain a relation graph of the influence of the initial concentration change of Mn (II) on the Mn (II) removing efficiency of vermiculite and ferric oxyhydroxide modified vermiculite, wherein the relation graph is shown in FIG. 7.
FIG. 7 shows that in the initial concentration range of 0.5-3mg/L (the concentration range is the concentration range where the underground water containing manganese is usually located), although the adsorption removal rate of vermiculite to Mn (II) in water before and after modification is reduced with the increase of the initial concentration, the removal rate of the iron oxyhydroxide modified vermiculite composite material to Mn (II) in water in the concentration range is not obviously reduced, and when the maximum concentration of raw water Mn (II) is 3mg/L, the removal rate can still reach more than 97%, and the residual concentration of Mn (II) in the treated water still meets the requirement of sanitary standard for drinking water GB5749-2006 on the manganese content of less than 0.1mg/L. The removal rate of the unmodified vermiculite on Mn (II) in the water is sharply reduced along with the increase of Mn (II) in raw water, when the concentration of Mn (II) in the raw water is only 1mg/L, the residual concentration of Mn (II) in the treated water is more than 0.1mg/L (0.12 mg/L), and the requirement of sanitary standard for drinking water GB5749-2006 cannot be met.
Example 6
The procedure is as in the first step of example 1.
Step two: 6g of pretreated vermiculite with 200ml of 0.25mol/L Fe (NO) 3 Stirring and mixing the solution, soaking and oscillating for 30min by using 400W ultrasonic waves at normal temperature, adjusting the pH value to 10 by using an alkaline solution, stirring and reacting for 60min, aging for 48 hours in a constant temperature box at 60 ℃, cooling, filtering and separating to obtain a primary product of the composite adsorbing material. Washing the primary product with deionized water to be nearly neutral, putting the product into a thermostat at 105 ℃ and drying the product to constant weight to obtain the ferric hydroxide modified vermiculite composite adsorption material;
step three: weighing 0.1000g (+ -0.0005 g) of the obtained composite adsorbing material, putting the material into a 250mL conical flask with a plug, adding 100mL of water sample with the initial concentration of 3mg/L Mn (II), putting the water sample into a constant temperature oscillator, fully oscillating (150r/min) at the temperature of 25 ℃, and stopping oscillating after adsorbing for 180 min;
step four: measuring the supernatant after shaking in the third step, passing through a 0.45 μm microporous filter membrane, and measuring the concentration of the residual Mn (II) in the filtrate by using an Shimadzu AA-7000 atomic absorption spectrophotometer. The adsorption removal rate of the modified vermiculite composite adsorption material to Mn (II) is 97.1%, and the concentration of Mn (II) in the treated water is 0.09 mg/L.
Example 7
The procedure is as in example 1.
Step two: 6g of pretreated vermiculite with 200ml of 0.25mol/L Fe (NO) 3 Stirring and mixing the solution, soaking and oscillating for 30min by using 400W ultrasonic waves at normal temperature, adjusting the pH value to 12 by using an alkaline solution, stirring and reacting for 60min, aging for 48 hours in a constant temperature box at 100 ℃, cooling, filtering and separating to obtain a primary product of the composite adsorbing material. Washing the primary product with deionized water to be nearly neutral, putting the product into a thermostat at 105 ℃ and drying the product to constant weight to obtain the ferric hydroxide modified vermiculite composite adsorption material;
step three: weighing 0.1000g (+ -0.0005 g) of the obtained composite adsorbing material, putting the material into a 250mL conical flask with a plug, adding 100mL L of a water sample with the initial concentration of 3mg/L of Mn (II), putting the water sample into a constant-temperature oscillator, fully oscillating (150r/min) at the temperature of 25 ℃, and stopping oscillating after adsorbing for 180 min;
step four: measuring the supernatant after shaking in the third step, passing through a 0.45 μm microporous filter membrane, and measuring the concentration of the residual Mn (II) in the filtrate by using an Shimadzu AA-7000 atomic absorption spectrophotometer. The adsorption removal rate of the obtained modified vermiculite composite adsorption material to Mn (II) is 98.4%, and the concentration of Mn (II) in the treated water is 0.05 mg/L.
Example 8
The procedure is as in the first step of example 1.
Step two: 6g of pretreated vermiculite with 200ml of 0.25mol/L Fe (NO) 3 Stirring and mixing the solution, soaking and oscillating for 30min by using 400W ultrasonic waves at normal temperature, adjusting the pH value to 12 by using an alkaline solution, stirring and reacting for 60min, aging for 24 hours in a constant temperature box at 60 ℃, cooling, filtering and separating to obtain a primary product of the composite adsorbing material. Washing the primary product with deionized water to be nearly neutral, putting the product into a thermostat at 105 ℃ and drying the product to constant weight to obtain the ferric hydroxide modified vermiculite composite adsorption material;
step three: weighing 0.1000g (+ -0.0005 g) of the obtained composite adsorbing material, putting the material into a 250mL conical flask with a plug, adding 100mL of water sample with the initial concentration of 3mg/L Mn (II), putting the water sample into a constant temperature oscillator, fully oscillating (150r/min) at the temperature of 25 ℃, and stopping oscillating after adsorbing for 180 min;
step four: measuring the supernatant after shaking in the third step, passing through a 0.45 μm microporous filter membrane, and measuring the concentration of the residual Mn (II) in the filtrate by using an Shimadzu AA-7000 atomic absorption spectrophotometer. The adsorption removal rate of the modified vermiculite composite adsorption material to Mn (II) is 97.3%, and the concentration of Mn (II) in the treated water is 0.08 mg/L.
Example 9
The procedure is as in the first step of example 1.
Step two: 6g of pretreated vermiculite with 200ml of 0.25mol/L Fe (NO) 3 Stirring and mixing the solution, soaking and shaking with 400W ultrasonic wave at normal temperature for 30min, adjusting pH to 12 with alkaline solution, stirring and reacting for 60min, aging in 200 deg.C thermostat for 48 hr, cooling, and filteringFiltering and separating to obtain the composite adsorbing material initial product. Washing the primary product with deionized water until the primary product is nearly neutral, and putting the primary product into a 105 ℃ thermostat to dry the primary product to constant weight to obtain the iron oxyhydroxide modified vermiculite composite adsorption material;
step three: weighing 0.1000g (+ -0.0005 g) of the obtained composite adsorbing material, putting the material into a 250mL conical flask with a plug, adding 100mL of water sample with the initial concentration of 3mg/L Mn (II), putting the water sample into a constant temperature oscillator, fully oscillating (150r/min) at the temperature of 25 ℃, and stopping oscillating after adsorbing for 180 min;
step four: measuring the supernatant after shaking in the third step, passing through a 0.45 μm microporous filter membrane, and measuring the concentration of the residual Mn (II) in the filtrate by using an Shimadzu AA-7000 atomic absorption spectrophotometer. The adsorption removal rate of the obtained modified vermiculite composite adsorption material to Mn (II) is 90.4%, and the concentration of Mn (II) in the treated water is 0.29 mg/L.
Example 10
The procedure is as in example 1.
Step two: 3g of pretreated vermiculite with 200ml of 0.25mol/L Fe (NO) 3 Stirring and mixing the solution, soaking and oscillating for 30min by using 400W ultrasonic waves at normal temperature, adjusting the pH value to 12 by using an alkaline solution, stirring and reacting for 60min, aging for 48 hours in a constant temperature box at 60 ℃, cooling, filtering and separating to obtain a primary product of the composite adsorbing material. Washing the primary product with deionized water to be nearly neutral, putting the product into a thermostat at 105 ℃ and drying the product to constant weight to obtain the ferric hydroxide modified vermiculite composite adsorption material;
step three: weighing 0.1000g (+ -0.0005 g) of the obtained composite adsorbing material, putting the material into a 250mL conical flask with a plug, adding 100mL L of a water sample with the initial concentration of 3mg/L of Mn (II), putting the water sample into a constant-temperature oscillator, fully oscillating (150r/min) at the temperature of 25 ℃, and stopping oscillating after adsorbing for 180 min;
step four: measuring the supernatant after shaking in the third step, passing the supernatant through a 0.45 mu m microporous filter membrane, and measuring the concentration of the residual Mn (II) in the filtrate by using an Shimadzu AA-7000 atomic absorption spectrophotometer. The adsorption removal rate of the obtained modified vermiculite composite adsorption material to Mn (II) is 98.7%, and the concentration of Mn (II) in the treated water is 0.04 mg/L.
Example 11 testing of iron Loading in iron oxyhydroxide-modified vermiculite sorbent materials
The preparation method of the iron oxyhydroxide-modified vermiculite adsorption material is the same as the first step and the second step of the example 1.
Step three: the composite adsorbent obtained above was weighed into a mixture of 0.1000g (+ -0.0005 g) and 30mL of 1: 1(V), placing into a vibrator, vibrating for 2h, heating in water at 90 deg.C for 20min, and cooling;
step four: measuring the supernatant after oscillation in the third step, passing the supernatant through a 0.45-micron microporous filter membrane, measuring the total iron content of the filtrate by using an Shimadzu AA-7000 atomic absorption spectrophotometer, and obtaining the total iron load of the modified vermiculite as 12.90mg/g and the load rate as 1.29 wt% through calculation.
Example 12 stability testing of iron oxyhydroxide-modified vermiculite adsorption Material
The preparation method of the iron oxyhydroxide-modified vermiculite adsorption material is the same as the first step and the second step of the example 1.
Step three: weighing 0.1000g (+ -0.0005 g) of each of the obtained composite adsorbing materials, respectively putting the materials into 250ml conical flasks with stoppers, adding 50ml double distilled water with pH values of 1, 2, 3, 4, 5, 7 and 9, which is pre-adjusted by hydrochloric acid and sodium hydroxide solution, placing the materials in a constant temperature oscillator, fully oscillating (150r/min) at 25 ℃ for 24 hours, and stopping oscillating;
step four: measuring the supernatant after oscillation in the third step, passing the supernatant through a 0.45-micron microporous filter membrane, and measuring the total iron concentration in the filtrate by using an Shimadzu AA-7000 atomic absorption spectrophotometer to obtain the total amount of iron ions desorbed into the solution of the iron oxyhydroxide modified vermiculite at different pH values, wherein the total amount is shown in table 2, so as to discuss the stability of the iron oxyhydroxide modified vermiculite.
As can be seen from Table 2, the ferric hydroxide modified vermiculite adsorption material has good stability in the aqueous solution with the pH value of more than 3.0, and the loaded ferric hydroxide is hardly desorbed and dissolved out.
TABLE 2 dissolution stability results for iron oxyhydroxide-modified vermiculite adsorption materials
Figure BDA0002419061950000111
The foregoing examples are set forth to provide a clear illustration of the invention and are not to be construed as limiting the scope thereof, which is defined in the claims appended hereto.

Claims (10)

1. Ferric hydroxide modified vermiculite composite adsorption material for removing Mn in manganese-containing underground water 2+ The use of (1); the method is characterized in that manganese-containing groundwater to be treated and the ferric oxyhydroxide modified vermiculite composite adsorption material are mixed and oscillated at constant temperature; wherein the mass volume ratio of the ferric hydroxide modified vermiculite composite adsorption material to the manganese-containing underground water is 0.4-4 g: 1000 mL; mn in the manganese-containing groundwater 2+ The initial concentration of (A) is 0.5-3mg/L, and the pH value is 6-9;
the preparation method of the iron oxyhydroxide modified vermiculite composite adsorption material comprises the following steps:
s1, washing vermiculite for multiple times, mixing the washed vermiculite with a dilute acid solution, stirring to react for 2-4 hours, carrying out solid-liquid separation, washing the vermiculite subjected to acid treatment until the washing liquid is neutral, drying, and sieving with a 40-mesh sieve and a 60-mesh sieve to obtain vermiculite with the particle size of 40-60 meshes for later use;
s2, placing the vermiculite subjected to S1 treatment in a water-soluble ferric salt solution, and performing ultrasonic oscillation for 30-60min to obtain a mixed solution;
s3, dropwise adding alkali liquor into the mixed liquor obtained in the step S2 while stirring until the pH value of the mixed liquor is 10-12, then continuously stirring for 30-120min, then aging at the constant temperature of 60-100 ℃ for 24-60h, cooling, and performing solid-liquid separation to obtain a composite adsorption material primary product;
and S4, washing the composite adsorbing material primary product obtained in the S3 for multiple times, drying, and cooling to obtain the iron oxyhydroxide modified vermiculite composite adsorbing material.
2. The use according to claim 1, wherein in S1, the pH value of the dilute acid solution is 1-3, and the mass-to-volume ratio of vermiculite to dilute acid solution is 1 g: 10-30 mL; the acid is hydrochloric acid and/or sulfuric acid.
3. The use according to claim 1, wherein in S1 and/or S4 the drying is performed at constant temperature.
4. Use according to claim 3, wherein the drying temperature is 80-105 ℃.
5. The use of claim 1, wherein in S2, the water-soluble ferric salt is ferric nitrate and/or ferric sulfate.
6. Use according to claim 5, wherein the water-soluble ferric salt is ferric nitrate.
7. The use of claim 1, wherein in S2, Fe is in the solution of the water-soluble ferric salt 3+ The concentration of (b) is 0.1-1 mol/L; the mass ratio of the water-soluble ferric salt to the vermiculite is 1:1-4: 1.
8. The use as claimed in claim 1, wherein in S2, the ultrasonic power is controlled to be 300-600W and the temperature of the water-soluble ferric salt solution is 20-30 ℃.
9. The use of claim 1, wherein in S3, the alkali solution is sodium hydroxide solution with a concentration of 1-3 mol/L.
10. The use according to claim 1, wherein in S3, the stirring is continued for 30-60 min.
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