CN114702961B - Amorphous ferro-manganese colloidal material and preparation method and application thereof - Google Patents

Abstract

The invention discloses an amorphous ferro-manganese colloidal material and preparation and application thereof. The preparation method of the amorphous ferro-manganese colloidal material comprises the following steps: mixing the spent grain leachate with ferric salt and manganese salt, adjusting the pH value, and then uniformly mixing for reaction to obtain the compound fertilizer, preferably, the spent grain leachate is obtained by ball milling and hydrothermal reaction. The method has the advantages of low energy consumption in the process, short preparation period, simple and controllable method, realization of large-scale programmed production, good migration performance of the prepared amorphous ferro-manganese colloidal material, and application to synchronous in-situ stabilization and restoration of arsenic and antimony pollution of soil, wherein the fixing rates of water-soluble arsenic and antimony can reach 100% and the fixing rates of effective arsenic and antimony can respectively reach 82.54% and 52.59% when the restoration material is added into the soil of an actual arsenic and antimony composite pollution field.

Description

Amorphous ferro-manganese colloidal material and preparation method and application thereof

Technical Field

The invention belongs to the field of arsenic and antimony polluted soil treatment, and particularly relates to an amorphous ferro-manganese colloidal material for in-situ remediation of arsenic and antimony polluted soil, and preparation and application thereof.

Background

The existing in-situ remediation technology for heavy metal contaminated soil mainly comprises physical remediation, chemical remediation, phytoremediation, microbial remediation, combined remediation and the like. These remediation methods can achieve contaminant removal quickly and efficiently, but these remediation techniques have various limitations. The cost is high when the treatment is not carried out by a soil-covering method and a soil-turning method, the risk of secondary pollution exists, the electric restoration technology is only suitable for small-area pollution, and the field operation difficulty is high; the phytoremediation technology takes longer time, and the high-concentration pollution level is not beneficial to plant growth; the microorganism treatment needs to consider the screening of strains, the variation effect of the environment on microorganisms and the like, so the method has comprehensive advantages and disadvantages, and the chemical in-situ stabilization restoration method has low cost, quick restoration effect, good restoration effect, wide applicability, small disturbance on soil and is often used for restoring heavy metal polluted soil.

The selection of an appropriate repair material is critical to the technique. It is known that iron-based materials are commonly used for arsenic or antimony polluted water treatment and soil remediation because abundant surface hydroxyl (-OH) groups can adsorb arsenate and antimonate to form an internal and external spherical complex. The complexation of the iron-based oxide with other heavy metals (such as Mn, ce, zr and Cu) changes the physical and chemical properties of the oxide and improves the adsorption capacity of the oxide to arsenic. The iron-manganese binary oxide combines the adsorption performance of iron and the oxidation performance of manganese, shows high-efficiency removal effect on As (V), as (III), sb (V) and Sb (III), and particularly has better removal effect on As (III) and Sb (III) with stronger toxicity, dissolubility and fluidity. However, most of the materials are used for water treatment, and the materials are rarely used for repairing arsenic and antimony polluted soil.

Because iron-based materials are typically low-mobility solid powder particles, the use of these materials to remediate soil and groundwater relies heavily on the mechanical mixing of remediation agents with remediation target materials. The fluidity of the iron-based material can also be improved by surface modification. Compared with the traditional surface modifier, the spent grain leachate is rich in soluble protein, soluble cellulose and the like, and is rich in a large number of functional groups, such as hydroxyl, carboxyl, secondary amide and the like, which are easily matched with metal ions for removing heavy metals. The invention utilizes the adsorbability and the dispersibility of the spent grains to react with the ferro-manganese bimetallic oxide to synthesize the colloidal material which can migrate in soil gaps and can be used for in-situ remediation of heavy metals in soil. The amorphous ferro-manganese colloidal material prepared by the invention can be used for in-situ remediation in an injection mode, and is also applicable to remediation of deep soil and contaminated soil at the bottom of an existing building, which are difficult to implement by a conventional method.

Disclosure of Invention

Aiming at the defect that the existing curing and stabilizing remediation material is difficult to be used for in-situ remediation, the invention aims to provide the colloidal material stabilizer which is environment-friendly, low in price and good in stability and can be used for in-situ remediation of low-pollution-degree arsenic and antimony composite polluted soil, and the preparation method and the application thereof. The amorphous ferro-manganese colloidal material has high mobility in soil and is suitable for repairing deep heavy metal polluted soil.

The amorphous ferro-manganese bimetallic oxide colloidal material provided by the invention comprises Mn (VI) and Mn (III) which provide oxidation, and Fe (III) which provides main adsorption; the main components of the spent grains can inhibit the agglomeration of iron and manganese oxides and the transformation of iron oxides, and the spent grains have the characteristics that a plurality of functional groups can adsorb heavy metals, the spent grains are rich in various functional groups such as hydroxyl groups, secondary amide groups and the like, and have amorphous or weak crystal structures, more surface structure defects and more reaction sites.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a ferro-manganese colloidal material comprises the following steps: mixing the spent grain leachate with ferric salt and manganese salt, adjusting the pH value, and then uniformly mixing and reacting to obtain the compound fertilizer; preferably, the mixture is stirred and mixed evenly at normal temperature for synthesis for at least 2 hours.

Preferably, the spent grain leachate is obtained by ball milling and hydrothermal reaction; brewery spent grain is preferred.

Spent grains belong to polymers of biomass such as lignocellulose and protein, and have a compact and stable structure, which limits the direct utilization value of the spent grains. The combination between the lignocelluloses can be physically destroyed and the dissolution of the soluble biomass can be increased through ball milling modification, and strong intramolecular and intermolecular hydrogen bonds can be broken, so that the carrying groups of the colloidal material can be increased.

Further, the preparation method comprises the steps of uniformly mixing the spent grain leachate with ferric salt and manganese salt; preferably, ferric salt and manganese salt are respectively dissolved in the spent grain leachate, then ferric salt solution and manganese salt solution are mixed, and further preferably, the pH value is adjusted to be 6-9.

The crystal form of the product is regulated and controlled by regulating and controlling the regulating rate of pH so as to obtain the target product which can keep a suspension state and is in an amorphous state.

Further preferably: respectively adding iron salt and manganese salt into 100ml of spent grain leachate, adding the iron salt solution into the manganese salt solution under the magnetic stirring of 200rpm, and adjusting the pH value to be 6-9, and preferably to be 7.5.

According to the preparation method, the weight ratio of the spent grain leachate to iron and manganese is 1-20 to 1.

In the preparation method, the molar concentration ratio of iron to manganese is 1.

In a preferred scheme, 2.862g of ferrous sulfate is used as the iron salt, and 0.138g of potassium permanganate is used as the manganese salt; dissolved in 100ml of spent grain leachate.

In the preparation method, the iron salt comprises at least one of ferrous sulfate, ferrous chloride and ferric nitrate; the manganese salt comprises at least one of potassium permanganate and manganese chloride; more preferably, ferrous sulfate is used as the iron salt, and potassium permanganate is used as the manganese salt.

The preparation method comprises the steps of using an alkaline solution containing at least one of ammonia water, sodium hydroxide and potassium hydroxide and an acidic solution containing at least one of sulfuric acid, nitric acid and hydrochloric acid to adjust the pH value of the solution; further preferably, the pH of the solution is adjusted by using an alkaline solution of sodium hydroxide and an acidic solution of hydrochloric acid.

Further preferable scheme selects 0.5mol/L sodium hydroxide and 0.5mol/L hydrochloric acid solution to adjust the pH value to 7.5.

After the pH value is adjusted, the preferred scheme system is continuously stirred for 2 hours to obtain the target amorphous iron-manganese colloidal material, wherein the concentration of iron ions is 0.09mol/L.

The pH value provides a certain oxidation-reduction environment for the formation of reaction products, the oxidation capability of reaction raw materials of permanganate is strongest under the strong acid condition, and the solubility of the products can be improved under the strong alkali condition to promote the recrystallization, so that the crystallinity of the products is improved. Therefore, the selection of an appropriate pH has a very important influence on the formation of the target product.

The preparation method is characterized in that the raw materials are mixed,

the mass ratio of the spent grains to the grinding balls is 1-1; preferably, the spent grains after passing through a 40-mesh sieve are ball-milled.

In a further preferable scheme, the mass ratio of the spent grains to the grinding balls is 1.

The ball mill adopted by the ball mill is one of a V-shaped ball mill, an inclined mixing ball mill and an all-directional planetary ball mill, and is preferably an all-directional planetary ball mill. The grinding ball is one of stainless steel grinding balls, zirconia grinding balls or agate grinding balls, and agate grinding balls are preferred.

The preparation method comprises the steps of dissolving 0.5-10 g of the spent grain powder in 1L of water with the temperature of 80-100 ℃, boiling for 30-120 min, and taking supernatant and cooling to obtain the spent grain leachate.

In a more preferred embodiment, 5g of the spent grain powder is boiled in 1L of 100 ℃ water for 30min.

The hydrothermal synthesis of the spent grain leachate has low energy consumption, saves the cost and has mild reaction conditions, so that intermediate state, metastable state and special substance which are difficult to obtain by other methods are easy to obtain, and nano-scale particles which are relatively uniformly dispersed, uniform in particle size and controllable in appearance can be obtained.

The invention also provides application of the ferro-manganese colloidal material to remediation of soil or underground water with low heavy metal pollution.

Further, the heavy metals include: at least one of arsenic and antimony.

Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:

1. the preparation process of the amorphous ferro-manganese colloid is simple and rapid, has low energy consumption and short period, and is easy to realize large-scale production;

2. the amorphous iron-manganese colloid has double effects of oxidation detoxification and adsorption on arsenic and antimony, and can oxidize As (III) and Sb (III) into As (V) and Sb (V) with low toxicity and weak migration capacity;

3. the amorphous ferro-manganese colloidal material can be directly used for stabilizing the soil polluted by arsenic and antimony, does not need freeze-drying treatment before use, and has better effect than solid immobilized material;

4. the amorphous ferro-manganese colloidal material has good migration performance, and can be used for in-situ remediation of antimony-arsenic pollution of soil or underground water by direct injection or spraying and other modes;

5. after the amorphous ferro-manganese colloidal material is injected into soil, the damage to the soil is small, and the material is green, economic and efficient. The in-situ remediation is carried out by means of injection, and the method is also suitable for remediation of deep soil and polluted soil at the bottom of the existing building, which are difficult to implement by the conventional method

6. The pH application range is wide, and the amorphous iron-manganese oxide can also keep good stability and fixation effect of arsenic and antimony under the condition of acid soil.

Drawings

FIG. 1 is an XRD pattern of the amorphous iron manganese colloidal material of example 1;

FIG. 2 is an SEM and EDX image of the amorphous iron-manganese colloidal material of example 1;

FIG. 3 is an FTIR spectrum of the amorphous iron manganese colloidal material of example 1;

FIG. 4 is a BET spectrum of the amorphous ferrimanganic colloidal material of example 1;

FIG. 5 is a graph showing the effect of the amorphous FeMn colloidal material of example 1 on the oxidation efficiency of As (III) and Sb (III) and the fixation ratio of total arsenic and total antimony;

FIG. 6 shows the suspensibility of the amorphous FeMn colloidal material modified by different dispersants at 48h in example 2;

FIG. 7 shows the effect of materials prepared with different molar ratios of synthesized Fe and Mn on the arsenic and antimony fixation rates;

FIG. 8 shows the fixation rate of effective arsenic and antimony in actual soil for materials prepared by different molar ratios of synthetic iron and manganese;

FIG. 9 shows the effect of the amount of the amorphous iron-manganese colloid on the fixation rate of arsenic and antimony in water-soluble and available states in actual soil;

FIG. 10 is a simulated penetration curve of a dispersant modified amorphous ferro-manganese colloidal material versus an unmodified amorphous ferro-manganese colloidal material in quartz sand;

FIG. 11 shows the fixation rate of the amorphous iron-manganese colloidal material to arsenic and antimony in soil in a simulated column experiment.

The removal rate in the present invention means a fixed rate.

Detailed Description

The technical solution of the present invention is further illustrated by the following specific examples, which are not intended to limit the scope of the claims of the present invention.

Example 1

Removing impurities such as silt and the like attached to the surface through water washing, drying at 60 ℃, grinding, and placing 5g of spent grains sieved by 40 meshes into a ball milling tank according to a ball-to-material ratio of 15: adding grinding balls into the mixture 1, wherein the ball mill is an all-directional planetary ball mill, setting the ball milling rotation speed to 320 revolutions per minute, screening the mixture through a 100-mesh sieve after ball milling for 8 hours, dispersing the mixture into 1L of deionized water boiling at 100 ℃, stirring the mixture for 30 minutes, and then filtering and cooling the mixture to room temperature to obtain the spent grain leachate (0.5 wt%). Thereafter, 2.8g of ferrous sulfate heptahydrate and 0.2g of potassium permanganate were dissolved in 100mL of the spent grain leachate, respectively. Next, the ferrous sulfate spent grain solution was slowly added to the potassium permanganate spent grain solution with magnetic stirring at 200rpm while adjusting the pH to 7.5 with 0.5mol/L sodium hydroxide. The system is continuously stirred for 2 hours to obtain the target amorphous iron-manganese colloid material, and the concentration of iron ions is 0.09mol/L. The XRD, SEM, EDX, FTIR and BET spectra are shown in FIG. 1, FIG. 2, FIG. 3 and FIG. 4, respectively. As can be seen from fig. 1, 2, 3 and 4, the obtained target product has an irregular bulk structure, and the iron and manganese elements are uniformly distributed, the diameter is mostly between 400 nm and 600nm, the aggregation degree among the particles is relatively small, and the material is a stabilizing material with an amorphous structure rich in hydroxyl on the surface. The target product has relatively stable chemical property, a small amount of iron and manganese can be leached under the condition of an acidic system (pH is less than 3), only a small amount of manganese can be leached under the condition of an alkaline system (pH is more than 9), and the material property is kept stable under a neutral condition. As shown in FIG. 5, the target product has the dual functions of oxidation detoxification and adsorption on arsenic and antimony, and can oxidize As (III) and Sb (III) into As (V) and Sb (V) with lower toxicity and lower migration capability. The amorphous iron-manganese material can completely oxidize 30mg/LAs (III) and Sb (III) into As (V) and Sb (V) within 24h, and completely remove arsenic, and the removal rate of antimony reaches 96.2%.

Example 2

Since the iron-manganese oxide is easy to agglomerate, the iron-manganese oxide is compared with the iron-manganese oxide modified by different dispersants in the present example, and then the suspension state is obtained. The specific method comprises the following steps: the synthesis method of the dispersant-free modified iron-manganese oxide comprises the following steps: respectively dissolving 2.8g of ferrous sulfate heptahydrate and 0.2g of potassium permanganate into 100ml of deionized water, magnetically stirring at 200rpm until the ferrous sulfate heptahydrate and the potassium permanganate are completely dissolved, slowly adding the ferrous sulfate solution into the potassium permanganate solution under the magnetic stirring, simultaneously adjusting the pH to 7.5 by using 0.5mol/L sodium hydroxide, and continuously stirring the system for 2 hours to obtain the dispersant-free modified iron-manganese oxide. The remainder being carboxymethylcellulose (CMC); rhamnolipids; xanthan gum; the synthesis method of the iron-manganese oxide modified by the starch and the spent grain leachate (treated in the same way as in example 1) comprises the following steps: 2.8g of ferrous sulfate heptahydrate and 0.2g of potassium permanganate were dissolved in 100ml of 0.5wt% carboxymethylcellulose (CMC), respectively; rhamnolipids; xanthan gum; slowly adding ferrous sulfate (carboxymethyl cellulose (CMC); rhamnolipid; xanthan gum; starch and spent grain leachate) solution into potassium permanganate (carboxymethyl cellulose (CMC); rhamnolipid; xanthan gum; starch and spent grain leachate) solution under magnetic stirring, magnetically stirring at 200rpm until complete dissolution, simultaneously adjusting pH to 7.5 with 0.5mol/L sodium hydroxide, and continuously stirring for 2h to obtain carboxymethyl cellulose (CMC); rhamnolipids; xanthan gum; starch and spent grain modified iron manganese oxide. Mixing an unmodified amorphous iron-manganese colloid material with carboxymethyl cellulose (CMC); rhamnolipids; xanthan gum; 50ml of the modified material of the starch and the spent grain leachate is placed in a colorimetric tube and is placed for 48 hours to observe the suspension state, as shown in fig. 6, the addition of the spent grain leachate can effectively improve the suspension property of the material, so that the repairing material is kept in a stable colloid state.

Example 3

2.516;2.621 of; 2.8 of; 2.862g ferrous sulfate heptahydrate and 0.484;0.378;0.2;0.138g of potassium permanganate are respectively dissolved in 100mL of the spent grain leachate with the mass fraction of 0.5 wt%. Next, the ferrous sulfate spent grain solution was slowly added to the potassium permanganate spent grain solution with magnetic stirring at 200rpm while adjusting the pH to 7.5 with 0.5mol/L sodium hydroxide. The system is continuously stirred for 2 hours to obtain a mixture with the molar ratio of iron to manganese of 3; 4; 8; 12, the amorphous iron-manganese colloid material has iron ion concentration of 0.045;0.047;0.05;0.051mol/L.

Example 4

In this example, 10mL of amorphous iron-manganese colloidal material was added to 10mL of 30mg/L As (III) or Sb (III) solution, respectively, as the starting material and reaction conditions for the preparation of the material were the same As in example 3. The mixture was equilibrated for 24 hours with mixing, and the results are shown in fig. 7. It can be seen that the colloidal materials with the molar ratios of iron and manganese of 8 and 12 have good removal effects on arsenic and antimony, and the colloidal material with the molar ratio of 8.

Example 5

In the application example 5, the soil is the composite polluted soil of the smelting site in the river basin region, and the water-soluble arsenic and antimony contents are respectively 5.15;2.44mg/kg, the content of effective arsenic and antimony is 95.1 respectively; 48.5mg/kg. Air drying, removing impurities, grinding, and sieving with 40 mesh nylon sieve.

Respectively weighing 10g of soil sample into a 100mL plastic bottle, adding the colloid materials with different molar ratios of iron and manganese prepared in the example 3 according to the material mass and the soil mass 1, uniformly mixing, stirring, sealing the bottle mouth with a sealing film, standing for 30 days, and airing the soil sample in an air drying box. Sampling and determining the content of available arsenic (dilute hydrochloric acid extraction state) and available antimony (EDTA extraction state) in the soil. Through detection, as shown in fig. 8, it can be seen that the colloidal materials with all molar ratios have good removal effects on the arsenic and antimony in the effective state, and the removal rates of the arsenic and antimony in the water-soluble state are both lower than the detection limit, so as to reach the discharge standard of the groundwater. At the moment, the removal rate of the ferro-manganese colloid material with the molar ratio of 12.

Example 6

The soil treatment method in this application example 6 was the same as in example 5.

Respectively weighing 10g of soil sample in a 100mL plastic bottle, and mixing the soil sample according to the mass ratio of the material to the soil of 1; 1;1.5 adding the colloid material prepared in the example 1 into the container, mixing and stirring uniformly, sealing the bottle mouth with a sealing film, standing for 7 days, and airing the soil sample in an air drying box. Sampling and determining the content of available arsenic (dilute hydrochloric acid extraction state) and available antimony (EDTA extraction state) in the soil. As shown in fig. 9, when the addition amount of the fixing agent is 1, the fixing effect is good, when the addition amount of the fixing agent reaches 1.

Example 7

The quartz sand column is filled by a wet method, pretreated 2 kinds of quartz sand (8-16 meshes, 16-30 meshes) with different particle sizes are respectively added from the top of the quartz column, and a plastic rod is used for beating the column body continuously in the column filling process so as to ensure uniform filling and prevent bubbles from being generated. Deionized water with 5 times of Pore Volume (PV) is introduced before the experiment, the pore volume of the quartz sand is obtained by measuring through a drainage method, the porosity of the quartz sand with 8-16 meshes and 16-30 meshes = the pore volume/the stacking volume of a column body, the measured porosity is respectively 0.44 and 0.40, the amorphous iron-manganese colloid material and the amorphous iron-manganese material which is not modified by the dispersant are injected from top to bottom through a peristaltic pump at the speed of 5ml/min, the total injection amount of the materials is 4 times of the pore volume, overflow liquid is collected at the bottom of the column, and the content of the iron element is obtained after the treatment with 20% HCl. Fig. 10 shows that the amorphous ferrimanganic colloidal material has similar penetration law in quartz sand with two particle sizes compared with the amorphous ferrimanganic material modified without the dispersant, the penetration performance of the amorphous ferrimanganic colloidal material is far better than that of the ferrimanganic colloidal material without the dispersant, and the penetration balance is achieved when 0.2PV and 0.4PV are injected respectively, and it can be seen that the larger the medium particle size is, the faster the amorphous ferrimanganic colloidal material penetrates.

Example 8

The contaminated soil column is filled by a dry method, the soil sample is the same as that in example 5, 1cm of quartz sand is filled at the bottom of the soil sample to prevent the soil sample from entering a pipeline, the texture of the used soil sample is tight due to the fact that cohesive soil is included, therefore, a migration test is carried out by means of a tool in a simulation practical engineering, when the soil sample is filled, a hose for injecting materials is inserted into the center of the soil column, two small holes are symmetrically poked at positions (from bottom to top) of 10cm and 25cm of the hose to promote migration of the materials in the soil column, the amorphous iron-manganese colloidal material is injected at an injection speed of 20mL/min by 4 times of pore volume, after the materials are injected, the soil is cultured for 7 days at room temperature, and analysis shows that the removal rate of water-soluble arsenic and antimony can reach 100%, wherein the removal rate of the effective arsenic can reach 55.35% at the highest, and the removal rate of the effective Sb can reach 40.62% at the highest.

Claims (14)

1. A preparation method of an amorphous ferro-manganese colloidal material is characterized by comprising the following steps: the method comprises the following steps: mixing the spent grain leachate with ferric salt and manganese salt, adjusting the pH value to 6-9, and then uniformly mixing and reacting to obtain the compound fertilizer; the molar concentration ratio of iron to manganese is 1;

dissolving 0.5-10 g of the wheat grains powder in 1L of water with the temperature of 80-100 ℃ and boiling for 30-120 min, and taking supernatant fluid, namely the wheat grains leaching solution;

mixing the spent grain leachate with iron and manganese according to the mass ratio of 1.

2. The production method according to claim 1, characterized in that: mixing the spent grain leachate with ferric salt and manganese salt at a constant speed.

3. The method of claim 2, wherein: respectively dissolving iron salt and manganese salt into the spent grain leachate, and then mixing the iron salt solution and the manganese salt solution.

4. The method of claim 1, wherein: the ferric salt comprises at least one of ferrous sulfate, ferrous chloride and ferric nitrate; the manganese salt comprises at least one of potassium permanganate and manganese chloride.

5. The method of claim 4, wherein: ferrous sulfate is used as iron salt, and potassium permanganate is used as manganese salt.

6. The method of claim 1, wherein: the molar concentration ratio of iron to manganese is 8.

7. The method of claim 6, wherein: the molar concentration ratio of iron to manganese is 8.

8. The method of claim 1, wherein: the pH value of the solution is adjusted by using an alkaline solution comprising at least one of ammonia water, sodium hydroxide and potassium hydroxide and an acidic solution comprising at least one of sulfuric acid, nitric acid and hydrochloric acid.

9. The method of claim 1, wherein: and adjusting the pH value of the solution by using a sodium hydroxide alkaline solution and a hydrochloric acid acidic solution.

10. The method of claim 1, wherein:

the mass ratio of the spent grains to the grinding balls is 1-5-1, the ball milling speed is 160-320 r/min, the ball milling time is 4-8 hours, and the spent grains are sieved by a 100-mesh sieve after ball milling to obtain spent grain powder.

11. The method for producing as claimed in claim 10, characterized in that: and ball milling the spent grains which are sieved by a 40-mesh sieve.

12. An amorphous ferro-manganese colloidal material is characterized in that: prepared by the process of any one of claims 1 to 11.

13. The use of the amorphous ferrimanganic colloidal material of claim 12, wherein: the method is used for repairing the soil or underground water with low heavy metal pollution degree.

14. Use according to claim 13, characterized in that: the heavy metals include: at least one of arsenic and antimony.

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