CN111285574B - Preparation method and application of bottom sediment heavy metal pollution remediation agent - Google Patents
Preparation method and application of bottom sediment heavy metal pollution remediation agent Download PDFInfo
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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Abstract
本发明公开了一种底泥重金属污染修复剂的制备方法，主要包括以下步骤：以藜为原料，水热法活化炭化生物质；厌氧条件下，低温热解炭化制备生物炭；生物炭与黏土、膨润土、高岭土搅拌均匀；加入十二烷基硫酸钠高速搅拌均匀；加入NaHCO3、KHCO3、Ca(HCO3)2、Mg(HCO3)2搅拌均匀；真空条件下，热处理1h‑2h；厌氧条件下，高温热解炭化制备底泥重金属污染修复剂。制备的生物炭修复剂克服了生物炭浮力大，不易沉降的缺点，实现了高效吸附水体和固定底泥中Cd2+、Pb2+、Cu2+和Hg2+。本发明还公开了底泥重金属污染修复剂在吸附水体和固定底泥中重金属污染物方面。
The invention discloses a preparation method of a sediment heavy metal pollution remediation agent, which mainly comprises the following steps: using quinoa as a raw material, hydrothermally activated carbonized biomass; under anaerobic conditions, low-temperature pyrolysis and carbonization to prepare biochar; Clay, bentonite, and kaolin are mixed well; add sodium lauryl sulfate and stir well at high speed; add NaHCO 3 , KHCO 3 , Ca(HCO 3 ) 2 , Mg(HCO 3 ) 2 and stir well; under vacuum conditions, heat treatment for 1h-2h ; Under anaerobic conditions, high temperature pyrolysis carbonization to prepare sediment heavy metal pollution remediation agent. The prepared biochar remediation agent overcomes the shortcomings of high buoyancy and is not easy to settle, and realizes efficient adsorption of Cd 2+ , Pb 2+ , Cu 2+ and Hg 2+ in water and fixed sediment. The invention also discloses that the heavy metal pollution remediation agent in the sediment is used in adsorbing the water body and fixing the heavy metal pollutants in the sediment.
Description
Technical Field
The invention relates to the field of water treatment, in particular to a bottom sediment heavy metal pollution repairing agent prepared by using biochar as a raw material and applied to adsorbing water and fixing heavy metal pollutants in bottom sediment.
Background
The disordered and illegal discharge of urban domestic sewage and industrial and agricultural wastewater causes serious heavy metal pollution of urban rivers. After the heavy metal pollutants enter the river water body, most of the heavy metal pollutants are settled to the bottom mud of the river channel through physical, chemical and biological actions. The heavy metal content in the bottom mud is often several times or even dozens of times of that in the overlying water body, and adverse effects are brought to the improvement of the water quality of the river water body and the pollution control. Once the heavy metals in the river bottom mud are released, the river water body pollution is aggravated. Therefore, the control of the release of the heavy metal pollutants in the bottom mud of the river is very significant for improving the ecological environment of the river.
At present, the sediment heavy metal pollution control technology mainly adopts a sediment dredging technology, a polluted sediment ex-situ remediation technology and a polluted sediment in-situ control technology. The in-situ polluted sediment control technology is a technology for repairing sediment pollution in situ and controlling pollutant migration and conversion without dredging. The in-situ pollutant controlling technology includes in-situ bottom mud covering, in-situ biological repairing, chemical repairing, etc. Biochar is a carbonaceous material prepared by pyrolysis and chemical conversion of biomass under oxygen-barrier conditions. The biochar has the physicochemical properties of abundant surface functional groups, changeable surface forms, various pore structures and the like. The biochar can adsorb and fix heavy metals in the bottom sediment by virtue of characteristics such as surface functional groups, morphological structures and the like, and prevent and control the migration and transformation of the heavy metals in the bottom sediment. Compared with other bottom mud repairing agents, the biochar has excellent heavy metal adsorption performance, and can effectively recover the ecological environment of the bottom mud. However, because the buoyancy of the biochar is large, the biochar is independently used as a bottom mud repairing agent, and the biochar cannot be settled to the bottom of a river due to the buoyancy, so that the heavy metal control effect of the bottom mud is influenced. Therefore, the existing technology for controlling the heavy metal in the bottom sludge by using the biochar only uses the biochar as one component of the bottom sludge repairing agent. The content of the biochar in the repairing agent is not high, so that the repairing effect of the heavy metal in the bottom mud is influenced.
The patent with publication number CN109264944A discloses a FeSO4The method for repairing mercury polluted bottom sediment by using modified biochar obviously cannot be used for in-situ repair of heavy metal pollution of bottom sediment due to the large buoyancy of the biochar. The patent with the publication number of CN110104913A discloses a bottom mud repairing agent and a method for applying the same to in-situ repairing of bottom mud. The patent with publication number CN108892342A discloses a water bodyAccording to the preparation method of the composite material for fixing the heavy metal in the bottom sediment, the phosphoric acid is used for modifying the biomass, the pollution is easily generated in the preparation process, and meanwhile, the biochar and the inorganic salt are simply mixed, so that the obtained composite material is not tightly combined, and the actual application is not facilitated.
Disclosure of Invention
The invention aims to improve the percentage content of the biochar in the bottom sediment repairing agent, enhance the capability of the repairing agent for adsorbing and fixing heavy metals, and overcome the defects of large buoyancy and difficult sedimentation of the biochar serving as the bottom sediment repairing agent. The method for preparing the heavy metal polluted bottom mud repairing agent by using the biochar as the raw material has high efficiency of adsorbing and curing heavy metals, and is environment-friendly.
A preparation method of a bottom mud heavy metal pollution repairing agent mainly comprises the following steps:
(1) taking chenopodium quinoa as a raw material, activating and carbonizing biomass by a hydrothermal method at 150-280 ℃, and collecting a sample;
(2) under the anaerobic condition, the biochar is prepared by pyrolysis and carbonization at 300-450 ℃;
(3) stirring the biochar and one or more of clay, bentonite and kaolin uniformly;
(4) adding sodium dodecyl sulfate, and stirring at high speed;
(5) adding NaHCO3、KHCO3、Ca(HCO3)2、Mg(HCO3)2One or more of the components are uniformly stirred;
(6) heat treatment at 120-200 deg.c under vacuum condition;
(7) and (3) preparing the bottom mud repairing agent by pyrolysis and carbonization at 500-650 ℃ under an anaerobic condition.
The application efficiency of the biochar to the treatment of the bottom sludge pollutants is closely related to the structure, the properties and the like of the biochar. In order to obtain biochar with good properties, the selection of the raw material of the biochar is very important.
Chenopodium quinoa is an annual herb, belongs to the genus Chenopodium of Chenopodiaceae, belongs to weed, is easy to reproduce, has large biomass, high cellulose content and developed void structure. According to the invention, the chenopodium quinoa is used as the biochar raw material, the biomass raw material yield is high, and the resource utilization of biomass waste is facilitated.
The metal oxide on the surface of the biochar has obvious influence on the heavy metal adsorption capacity of the biochar. The Chenopodium quinoa has strong environmental adaptability, grows well under the condition of high-concentration metal, and has the enrichment capacity of various metals. In order to ensure that the prepared biochar surface is provided with enough metal oxides, Fe is applied in a spraying mode every day in the growing process of the chenopodium quinoa2(SO4)3、Al2(SO4)3、NiSO4Application of Fe2(SO4)3The concentration is 50mg/L-200mg/L, Al2(SO4)3The concentration is 50mg/L-100mg/L, NiSO4The concentration is 100mg/L-200mg/L, and the administration is continuously carried out for 120 days-180 days. Collecting mature Chenopodium quinoa plants, and drying at room temperature.
The invention applies Fe2(SO4)3、Al2(SO4)3、NiSO4The concentration is beneficial to the growth of the chenopodium quinoa and ensures the enrichment of Fe, Al and Ni.
Soaking Chenopodium quinoa in KCl or K under vacuum2CO3、K2SO4Or KNO3In one or more solutions of (A), KCl, K2CO3、K2SO4、KNO3The concentration is 0.1g/L-0.5g/L respectively.
Under the vacuum condition, potassium ions are embedded into the quinoa cellulose, so that the specific surface area of the biochar is increased, and the biochar yield is improved. At the same time, KCl, K2CO3、K2SO4Or KNO3，Mineral substances are formed on the surface of the biochar, and the heavy metal adsorption and fixation capacity of the biochar is improved. In addition, the high-concentration potassium ions on the surface of the biochar are beneficial to improving the heavy metal adsorption capacity of the biochar through an ion exchange mechanism.
KCl、K2CO3、K2SO4Or KNO3The concentration is 0.1g/L-0.5 g/L.
Preferably, the KCl concentration is 0.5g/L, or 0.1 g/L.
Preferably, K is2CO3The concentration was 0.2 g/L.
As a preference，K2SO4The concentration was 0.2 g/L.
Preferably, KNO3，The concentration was 0.1 g/L.
According to the technical scheme, the Chenopodium quinoa is used as a raw material, and the biomass is activated and carbonized by a hydrothermal method at the temperature of 150-280 ℃. According to the technical scheme, a hydrothermal method is adopted, so that the formation of Fe, Al and Ni metal oxides in a chenopodium plant body is facilitated, potassium ions are embedded into chenopodium cellulose, the content of oxygen-containing functional groups on the surface of biochar can be increased, the hydrophilicity of the biochar is improved, and the combination efficiency of the biochar with clay, bentonite and kaolin is improved.
Preferably, the carbonized biomass is activated by a hydrothermal method at 150 ℃, so that the generation efficiency of the aluminum-containing oxide is improved.
Preferably, the carbonized biomass is activated by a hydrothermal method at 220 ℃ or 280 ℃, so that the generation efficiency of the iron-containing oxide is improved.
According to the technical scheme, after the biomass is activated and carbonized by a hydrothermal method, the biochar is prepared by low-temperature pyrolysis and carbonization.
In the technical scheme of the invention, under the anaerobic condition, the temperature is raised to 300-450 ℃ at 1-5 ℃/min, and the temperature is maintained for 0.5-1 h. The heating rate is slower, the carbonization temperature is lower, the loss of oxygen-containing functional groups on the surface of the biochar is reduced, the hydrophilicity of the biochar is kept, and the combination efficiency of the biochar with clay, bentonite and kaolin is further improved.
Preferably, the temperature is raised to 300 ℃ by 1 ℃/min, or to 450 ℃ by 3 ℃/min, or to 450 ℃ by 5 ℃/min.
In the technical scheme of the invention, the biochar is uniformly stirred with one or more of clay, bentonite and kaolin. The clay, bentonite or kaolin can effectively increase the quality of the repairing agent, accelerate the settling rate of the biochar and reduce the buoyancy of the biochar.
As the subsequent pyrolysis process further influences the properties of the repairing agent such as carbonization rate, specific surface area, pore size and the like, in order to ensure that the repairing agent has rapid sedimentation and high-efficiency heavy metal adsorption and solidification capacity, the repairing agent of the technical scheme comprises 90-70% of biochar by mass and 5-20% of clay, bentonite and kaolin by mass. The ratio of the biochar is far higher than that of clay, bentonite or kaolin, so that the heavy metal restoration efficiency of the restoration agent is ensured, the heavy metal solidification capability of the restoration agent is enhanced, and the quick sedimentation of the restoration agent is also ensured. Meanwhile, in the high-temperature cracking process, the clay, bentonite or kaolin with certain content is beneficial to obtaining the biochar with higher pore volume.
Preferably, when the subsequent pyrolysis temperature is 550 ℃, the mass fraction of the biochar is 90 percent, and the mass fraction of the clay is 8 percent.
Preferably, when the subsequent pyrolysis temperature is less than or equal to 550 ℃, the mass fraction of the biochar is 85 percent, and the mass fraction of the clay is 5 percent; or the mass fraction of the biochar is 85 percent, and the mass fraction of the kaolin is 5 percent; or 80% of biochar and 10% of bentonite.
Preferably, when the subsequent pyrolysis temperature is higher than 550 ℃, the mass fraction of the biochar is 70 percent, and the mass fraction of the kaolin is 20 percent; or the mass fraction of the biochar is 75 percent, and the mass fraction of the clay is 15 percent; or the mass fraction of the biochar is 75 percent, and the mass fraction of the bentonite is 20 percent.
Preferably, when the subsequent pyrolysis temperature is 650 ℃, the mass fraction of the biochar is 70%, the mass fraction of the clay is 5%, the mass fraction of the bentonite is 10%, and the mass fraction of the kaolin is 5%.
In the technical scheme of the invention, sodium dodecyl sulfate is added and stirred uniformly at a high speed. The sodium dodecyl sulfate enables air to permeate when the sodium dodecyl sulfate is physically stirred at a high speed, so that the repairing agent is favorable for forming a porous structure, and the specific surface area and the heavy metal curing capacity of the repairing agent are enhanced. In the subsequent preparation process of the biochar, the lauryl sodium sulfate is heated and decomposed to generate sulfides, and the sulfides generated on the surface of the biochar are favorable for the biochar to solidify the heavy metals in the bottom sludge.
Preferably, the mass fraction of sodium lauryl sulfate is 2%.
In the technical scheme of the invention, NaHCO is added3、KHCO3、Ca(HCO3)2、Mg(HCO3)2One or more of the components are uniformly stirred; bicarbonate mass fractionThe number is 5% -10%; heat treatment is carried out for 1h-2h at the temperature of 120-200 ℃ under the vacuum condition.
The technical proposal of the invention adds bicarbonate to be heated and decomposed to generate CO2The method is favorable for forming pore diameters with different sizes in the repairing agent and increasing the specific surface area. According to the technical scheme, the vacuum slow heating is adopted, so that gas transmission is facilitated, and the aperture generation efficiency of the repairing agent is improved. Meanwhile, the bicarbonate is heated and decomposed to generate carbonate which is loaded on the surface of the biochar, so that the mineral content of the biochar is increased, the sedimentation rate of the biochar is accelerated, and the heavy metal curing efficiency of the biochar on the bottom sludge is improved.
Preferably, the temperature is raised to 200 ℃ at a rate of 1 ℃/min for 2 hours.
Preferably, NaHCO3The mass fraction is 8%; or KHCO3The mass fraction is 5 percent; or Ca (HCO)3)2The mass fraction is 10 percent; or Mg (HCO)3)2The mass fraction is 10%.
According to the technical scheme, after the biomass is activated and carbonized by a hydrothermal method, the biomass is pyrolyzed and carbonized at a low temperature to prepare the biochar, and then pyrolyzed and carbonized at a high temperature to prepare the biochar. Under the anaerobic condition, the temperature is raised to 500-650 ℃ at 30-50 ℃/min, and the temperature is maintained for 2-3 h.
According to the technical scheme, the biochar is prepared through high-temperature pyrolysis again, so that the hydrophobicity of the biochar is improved, the specific surface area and the pore volume of the biochar are increased, the mineral content of the biochar is increased, the sedimentation rate of the biochar is improved, and the heavy metal curing efficiency of the bottom sediment by the repairing agent is improved. Meanwhile, the thermal decomposition of the sodium dodecyl sulfate is facilitated to generate sulfide under the high-temperature condition.
Preferably, the temperature is raised to 500 ℃ at a rate of 50 ℃/min under anaerobic conditions and maintained for 3 hours.
Drawings
FIG. 1 is a flow chart of the preparation of a biochar repair agent;
FIG. 2 is an SEM-Mapping diagram of the heavy metal Cd in the solidified bottom mud of the biochar.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Example 1
(1) Transplanting Chenopodium quinoa with plant height of about 10 cm;
(2) preparing Hoagland nutrient solution, and adding Fe2(SO4)3、Al2(SO4)3Or NiSO4In which Fe2(SO4)3The concentration is 50mg/L-200mg/L, Al2(SO4)3The concentration is 50mg/L-100mg/L, NiSO4The concentration is 100mg/L-200mg/L,
(3) the culture solution was continuously applied by spraying for 180 days. Chenopodium quinoa has good growth.
(4) Preparing Hoagland nutrient solution, and adding Fe2(SO4)3、Al2(SO4)3And NiSO4In which Fe is contained2(SO4)3Concentration of 200mg/L, Al2(SO4)3Concentration of 100mg/L, NiSO4The concentration is 200 mg/L;
(5) applying the culture solution in a spraying mode for 160 days continuously;
(6) collecting the Chenopodium quinoa plants, and drying at room temperature.
(7) The contents of Fe, Al, Ni and cellulose in Chenopodium quinoa were measured and are shown in Table 1.
TABLE 1 Chenopodium quinoa Fe, Al, Ni, cellulose content
| Analysis of parameters | Content, percentage |
| Fe（mg/g） | 4.298±0.258 |
| Al（mg/g） | 3.109±0.143 |
| Ni（mg/g） | 4.794±0.199 |
| Cellulose, process for producing the same, and process for producing the same | 29.5% |
Example 2
(1) Taking the biomass collected in example 1;
(2) immersing biomass in KCl and K under vacuum condition2CO3、K2SO4Or KNO3Is immersed for 24 hours in one or more of the solutions, as shown in table 2;
TABLE 2 impregnation of Potassium salt types
| Composition of matter | Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 |
| KCl | 0.5g/L | 0.1g/L | － | － | － | 0.5g/L |
| K2CO3 | － | － | 0.2g/L | － | － | － |
| K2SO4 | － | － | 0.2g/L | 0.2g/L | － | － |
| KNO3 | － | 0.1g/L | － | － | 0.2g/L | 0.1g/L |
(3) The carbonized biomass was activated by hydrothermal method at 150-280 deg.C, as shown in Table 3.
TABLE 3 temperature for activating and carbonizing biomass by hydrothermal method
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Temperature/. degree.C | 150℃ | 200℃ | 200℃ | 220℃ | 250℃ | 280℃ |
(4) Under the anaerobic condition, heating to 300-450 ℃ at the speed of 1-5 ℃/min, and maintaining for 0.5-1 h, as shown in Table 4;
TABLE 4 biochar Low temperature carbonization
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Temperature/. degree.C | 300℃ | 300℃ | 350℃ | 350℃ | 450℃ | 450℃ |
| Rate of temperature rise | 1℃/min | 1℃/ |
2℃/min | 5℃/min | 3℃/min | 5℃/min |
| Time/h | 0.5h | 1h | 0.5h | 1h | 1h | 1h |
(5) Collecting a biochar sample;
(6) mixing biochar with clay, bentonite or kaolin, as shown in Table 5;
(7) sodium lauryl sulfate was added as shown in table 5.
TABLE 5 component composition in percent by mass of repair agent
| Composition of matter | Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 |
| Biochar | 90% | 85% | 85% | 80% | 75% | 70% |
| Clay | － | 5% | － | 5% | 3% | 5% |
| Bentonite clay | － | － | 10% | － | 5% | 10% |
| Kaolin clay | 5% | － | － | － | 10% | 5% |
| Sodium dodecyl sulfate | 1% | 1% | 3.5% | 5% | 2% | 2% |
(8) Stirring at 1200rmp for 2-4 h;
(9) NaHCO was added as shown in Table 63、KHCO3、Ca(HCO3)2Or Mg (HCO)3)2；
TABLE 6 bicarbonate in percent by weight
| Composition of matter | Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 |
| NaHCO3 | 8% | 8% | － | 5% | － | － |
| KHCO3 | － | － | 5% | 5% | － | － |
| Ca(HCO3)2 | － | － | － | － | 10% | － |
| Mg(HCO3)2 | 10% | － | － | － | － | 10% |
(10) Under the vacuum condition, the temperature is raised to 120-200 ℃ at the speed of 1-5 ℃/min, and the temperature is maintained for 1-2 h, as shown in Table 7.
TABLE 7 sample temperature ramp and ramp rate
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Temperature of | 120℃ | 150℃ | 150℃ | 180℃ | 200℃ | 200℃ |
| Rate of temperature rise | 1℃/min | 1℃/min | 5℃/min | 5℃/min | 5℃/min | 5℃/min |
| Time | 1h | 1h | 2h | 1h | 2h | 2h |
(11) Under the anaerobic condition, the temperature is raised to 500-650 ℃ at 30-50 ℃/min, and the temperature is maintained for 2-3 h, as shown in Table 8.
TABLE 8 high temperature carbonization of biomass
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Temperature of | 500℃ | 500℃ | 600℃ | 600℃ | 650℃ | 650℃ |
| Rate of temperature rise | 30℃/min | 30℃/min | 35℃/min | 45℃/min | 50℃/min | 50℃/min |
| Time | 2h | 3h | 2h | 3h | 2h | 3h |
Example 3
(1) According to 100g-1000g/m2The bottom sediment remediation agents were dosed as shown in table 9 below.
TABLE 9 application rates of restorative agents
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Amount of application | 100g/m2 | 500g/m2 | 500g/m2 | 800g/m2 | 1000g/m2 | 1000g/m2 |
(2) And respectively detecting the heavy metal content of the overlying water body and the heavy metal residue state percentage of the bottom mud in 0 day, 30 days and 45 days (tables 10-17).
(3) Taken in example 3, repairCd is adsorbed and fixed by an adsorbent2+Scanning electron microscope analysis is carried out on the biochar, and SEM-Mapping proves that Cd is fixed by the biochar2+Then, Cd2+Can be CdCO3The form exists on the surface of the biochar (figure 2).
TABLE 10 Cd content (mg/L) of overlying water before and after application
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Day 0 | 0.2 | 0.2 | 0.25 | 0.15 | 0.17 | 0.2 |
| 30 days | 0.15 | 0.1 | 0.12 | 0.01 | 0.01 | 0.01 |
| 45 days | － | － | － | － | － | － |
TABLE 11 percentage of Cd residue in the sediment (%)
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Day 0 | 12.35 | 11.01 | 12.72 | 14.57 | 11.22 | 12.45 |
| 30 days | 43.65 | 47.41 | 53.69 | 55.44 | 52.34 | 53.39 |
| 45 days | 69.72 | 61.22 | 66.19 | 67.82 | 71.64 | 75.28 |
TABLE 12 Water Pb content (mg/L) of overlying water before and after application
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Day 0 | 0.24 | 0.31 | 0.53 | 0.51 | 0.51 | 0.47 |
| 30 days | 0.18 | 0.13 | 0.21 | 0.01 | 0.01 | 0.01 |
| 45 days | － | － | － | － | － | － |
TABLE 13 percentage of Pb residues in the sediment (%)
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Day 0 | 12.4 | 13.57 | 11.27 | 18.45 | 12.34 | 10.98 |
| 30 days | 23.42 | 23.89 | 30.18 | 34.75 | 43.23 | 49.09 |
| 45 days | 79.27 | 68.18 | 67.93 | 65.5 | 74.19 | 74.64 |
TABLE 14 Cu content (mg/L) of overlying water before and after application
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Day 0 | 1.72 | 1.9 | 2.02 | 2.2 | 2.79 | 3.56 |
| 30 days | 0.08 | 0.13 | 0.57 | 0.67 | 0.28 | 0.47 |
| 45 days | － | － | 0.01 | － | － | 0.02 |
TABLE 15 percentage of sediment Cu sludge state (%)
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Day 0 | 9.72 | 12.21 | 8.72 | 8.18 | 11.21 | 10.21 |
| 30 days | 33.21 | 48.05 | 43.64 | 48.97 | 52.12 | 57.77 |
| 45 days | 65.47 | 66.12 | 70.17 | 72.81 | 77.29 | 80.12 |
TABLE 16 Hg content (ng/L) of overlying water before and after application
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Day 0 | 12.3 | 17.5 | 13.75 | 32 | 34.53 | 27.36 |
| 30 days | 5.35 | 10.21 | 9.72 | 10.76 | 12.32 | 11.43 |
| 45 days | － | － | － | － | － | － |
TABLE 17 percentage of Hg residue in sediment (%)
| Sample 1 | |
Sample 3 | Sample No. 4 | Sample No. 5 | Sample No. 6 | |
| Day 0 | 9.45 | 10.13 | 11.98 | 15.78 | 9.23 | 3.56 |
| 30 days | 25.76 | 35.12 | 39.05 | 38.04 | 38.75 | 40.21 |
| 45 days | 50.51 | 53.63 | 43.39 | 52.21 | 59.94 | 50.32 |
Claims (6)
1. The preparation method of the bottom sediment heavy metal pollution repairing agent is characterized by comprising the following steps:
(1) taking chenopodium quinoa as a raw material, activating and carbonizing biomass by a hydrothermal method at 150-280 ℃, and collecting a sample;
(2) under the anaerobic condition, the biochar is prepared by pyrolysis and carbonization at 300-450 ℃;
(3) uniformly stirring biochar and one or more of clay, bentonite and kaolin, wherein the mass fraction of the biochar is 90% -70%, and the mass fractions of the clay, the bentonite and the kaolin are respectively 5% -20%;
(4) adding sodium dodecyl sulfate, and uniformly stirring at a high speed, wherein the mass fraction of the sodium dodecyl sulfate is 1-5%;
(5) adding NaHCO3、KHCO3、Ca(HCO3)2、Mg(HCO3)2One or more of the components are uniformly stirred;
(6) heat treatment at 120-200 deg.c under vacuum condition;
(7) preparing a bottom mud repairing agent by pyrolysis and carbonization at 500-650 ℃ under an anaerobic condition;
wherein, in the step (1), the Chenopodium quinoa is soaked in KCl and K under the vacuum condition2CO3、K2SO4Or KNO3In one or more solutions of (A), KCl, K2CO3、K2SO4、KNO3The concentration is 0.1g/L-0.5g/L respectively; in the step (5), the mass fraction of the bicarbonate is 5-10%.
2. The preparation method of the bottom sediment heavy metal pollution remediation agent of claim 1, wherein in the step (2), the temperature is raised to 300 ℃ -450 ℃ at a rate of 1 ℃/min-5 ℃/min under anaerobic conditions, and the temperature is maintained for 0.5h-1 h.
3. The preparation method of the bottom sediment heavy metal pollution remediation agent of claim 1, wherein in the step (6), the temperature is raised to 120-200 ℃ at a rate of 1-5 ℃/min under vacuum, and the temperature is maintained for 1-2 h.
4. The preparation method of the bottom sediment heavy metal pollution remediation agent of claim 1, wherein in the step (7), the temperature is raised to 500 ℃ -650 ℃ at 30 ℃/min-50 ℃/min under anaerobic conditions, and the temperature is maintained for 2h-3 h.
5. The application of the bottom sediment heavy metal pollution remediation agent of claim 1 in adsorbing heavy metal pollutants in water and fixing bottom sediment.
6. The application of the bottom sediment heavy metal pollution remediation agent of claim 5, wherein the remediation agent is 100g/m in terms of adsorption of heavy metal pollutants in water and immobilization of the bottom sediment2-1000g/m2Applied to the heavy metal polluted bottom mud to adsorb Cd in water and fix the bottom mud2+、Pb2+、Cu2+、Hg2+One or more of them.
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