CN106126894A - The method using carbon nanomaterial regulation and control consumer garbage compost Cd release power - Google Patents

Abstract

The invention discloses the method using carbon nanomaterial regulation and control consumer garbage compost Cd release power, it is the pvc pipe using leaching pipe, gauze back cover is used at the bottom of pipe, in each post, river sand 20g height 1 2cm filled by bottom, and upper strata is filled the carbon nanomaterial of 150g consumer garbage compost and 1% (w/w) and formed mixed-matrix.The drip washing of simulation Summer Heavy Rainfall, leaching pipe stands ripening 30 days, adds appropriate distilled water in giving pipe every day, and in pipe, soil moisture content is field capacity, period, indoor temperature 18～25 DEG C, relative humidity 35%～65%, illumination is the natural light penetrating indoor, 6856LX 27090LX, 30th day, carrying out Leaching Experiments, leaching liquor atomic absorption spectrophotometer TAS 990 measures the concentration of wherein heavy metal Cd.The present invention further discloses the method using carbon nanomaterial regulation and control consumer garbage compost Cd release power application in terms of improving the kinetics degree of fitting of Cd.

Description

A method of regulating the release power of Cd in domestic waste composting by using carbon nanomaterials

technical field

The invention belongs to the technical field of environmental protection and relates to a method for regulating and controlling the Cd release power of domestic garbage composting by using carbon nanometer materials.

Background technique

Household garbage mainly refers to the solid waste generated in residents' daily life and production. Global domestic waste will increase by 51% from 2005 to 2025. The average annual growth rate of domestic waste in my country exceeds 15%, and the accumulation of waste piles across the country has occupied more than 500 million square meters of land. By 2015, the annual domestic waste production in some of our cities is expected to exceed 10 million tons. The distribution of physical components of domestic waste is mainly inorganic matter such as glass, brick tiles, and cinder ash, and organic matter such as plants, fibers, plastics, and paper, among which compostable matter accounts for more than 30%. The chemical components are mainly water, N, P, K, organic matter, etc., and the moisture content of domestic waste in some areas exceeds 50%.

At present, the commonly used domestic waste disposal methods mainly include sanitary landfill, incineration and high-temperature composting. Sanitary landfill has become the main method for most cities to deal with domestic waste. However, sanitary landfill occupies a large amount of land. As the daily output of domestic garbage increases year by year, the phenomenon of garbage siege becomes more and more serious, and the direct landfill of garbage with high moisture content produces more leachate, which contains more harmful substances and produces A large amount of greenhouse gases can easily cause secondary pollution. Incineration treatment converts combustible waste into residues, reduces the amount of landfill, and kills pathogens and parasites in high-temperature combustion, and the heat generated can be used for heating and power generation. However, incineration converts some pollutants from solid to gaseous, and the tail gas contains complex pollutants, especially dioxins, which are highly toxic substances and have strong retention in the environment. Composting refers to the process of fermenting and degrading organic matter in garbage by microorganisms under certain artificial conditions to form stable humus. It is a resourceful, stable and harmless solid waste disposal method. After composting domestic waste, it is rich in organic matter, nitrogen, phosphorus and other nutrients, and after harmless treatment, it can be used as fertilizer to improve the soil environment, which has a good application prospect. At the same time, it should be pointed out that there are also Among them, the high content of heavy metals and other risks. Each treatment method requires different components of garbage, and a single mode of treatment cannot achieve true harmlessness. Combining multiple treatment methods for different main components of garbage has become the general trend of garbage treatment.

Compost is rich in organic matter and nutrients needed for plant growth. Studies have shown that the content of organic matter, N, K, and lignin in domestic waste compost is relatively high. Adding compost as fertilizer to the soil can improve soil fertility, increase soil water holding capacity, improve soil physical and chemical properties, and promote plant growth. Improve crop yields. Studies have shown that composting and chemical fertilizers from farmland waste are applied to the soil separately, and cabbage is planted, and the growth status of the crops, the number of pests, and the economic benefits are compared. The results show that although the number of pests in the soil with compost is twice that of chemical fertilizers, the economic benefits are three times. After Zhang Chunying ^[21] mixed garbage compost and original soil in different proportions, adding 5% to 20% of garbage compost can significantly increase the content of organic matter, available phosphorus and total nitrogen, and increase the dry weight of flowers above and below the ground; among them, when adding 10% compost , The underground dry weight is 3.61 times that of the control. Studies have shown that after using compost to improve the soil and planting chicory, the fertility of the soil is significantly increased, and the yield of chicory is significantly increased. Tang Shaojie rotated winter wheat and summer corn on the composted soil. After the crops were composted with domestic waste, the yield increase rate of corn increased significantly, reaching 43.4%. The increase rate of wheat yield in 2008 and 2009 was 53.6% and 99.2% respectively. There are also studies showing that the application of compost in sandy soil can increase the carbon-nitrogen ratio in the soil, increase the content of P, K, and Mg, and is beneficial to increase soil humus. However, even small amounts of compost from industrial areas can cause a significant increase in heavy metal content. Regardless of the effects of heavy metals, adding compost can significantly improve soil quality.

The composting of domestic waste in my country is affected by the factors of unclear classification of source waste. Domestic waste is mixed with materials rich in heavy metals such as batteries and electronic devices. Li Qiwei and other studies have shown that after domestic waste is composted, the total amount of heavy metals does not change significantly, and the stable content of Hg, Pb, Cr and other elements increases. Studies by Zhang Jing et al. have shown that Pb, Cd, and Zn transform from other forms to Fe-Mn combined state during the composting process, but due to the decrease in pH during the composting process, the bioavailable state of Pb, Cu, and Zn slightly increases. The application of domestic waste compost will increase the content of heavy metals in the soil, and at the same time increase the transfer of heavy metals in the soil to plants, which will bring certain ecological risks. Shao Huawei studied the distribution of heavy metals in various organs of maize after domestic waste composting: root>stem>leaf>grain. The results showed that the nutrient content in the fertilized soil increased for three consecutive years, but the heavy metal content also accumulated, and the Cd content was 0.416 mg ·kg ^-1 , Pb is 21.6 mg·kg ^-1 , and will not cause soil heavy metal pollution for the time being within 3 years. Ge Chunhui's research found similar results. After the application of garbage compost, the organic matter and available nutrients in the soil increased with the increase of compost content. However, the negative effect was that the content of heavy metals increased at the same time. %, although it has not exceeded the national standard, but long-term use needs further monitoring. It can be seen that the application of domestic waste compost can increase the content of heavy metals in the soil to a certain extent, and then increase the content of heavy metals in the crops. Composting in agriculture can improve soil fertility in the short term, but it needs to be monitored in time for years of application.

As the main component of urban greening construction, lawn provides leisure and entertainment places for urban residents. Whether you can have high-quality lawn green space is one of the important criteria for urban modernization. Nowadays, most of the land used for urban greening is old city demolition land or construction land, etc. The soil quality is poor and lacks fertility. Traditional lawn planting adopts the overall laying of turf rolls, which consumes a large amount of high-quality farmland. Fertilizing the lawn can effectively improve the quality of the lawn, adding nutrients to the lawn in time can improve the quality of the lawn, and adding compost can increase the germination rate of lawn plants. Compost has a significant impact on the ecology and quality characteristics of turfgrass. After adding it, it can increase the biomass of turfgrass and promote growth; it can also accelerate the rejuvenation of plants, and promote the density, texture, and coverage of plants in the second year. Studies by Ntoulas and others have shown that adding 12.5% compost to the planting of wolf tooth grass lawn can significantly improve the quality of the lawn and promote the growth of roots and leaves. Garbage compost can significantly improve the soil, improve fertilizer efficiency, and increase the nutrient content in the soil. Additionally, compost can serve as a soilless turf substrate. Domestic waste compost and bean straw are made into a composite substrate. With a low ratio of soybean straw, seed germination, net photosynthetic amount and chlorophyll of a single plant on the ground are all improved, and the composite substrate of compost and bean straw can be used to replace soil to build lawns . Tall fescue was planted with domestic waste compost of different particle sizes, and the results showed that domestic waste compost with small particle size (300-600nm) could increase the chlorophyll content of tall fescue, promote root growth, and relieve water stress. Drought damage, increased drought resistance. For microorganisms and soil animals, adding compost can inhibit lawn pathogens, not only can reduce lawn diseases, but also slow down lawn drug resistance. After adding compost, the dominant genus of soil nematodes in the turf construction value system changed, which inhibited the growth and reproduction of plant parasitic groups and created a good environment for turf growth.

The use of domestic waste compost in the lawn planting system can effectively improve the organic matter and nutrient content of the soil, and the heavy metals enriched in lawn plants are not enriched along the food web, reducing the risk of entering the human body and endangering health. However, the accumulation of heavy metals in soil after long-term use is still not to be underestimated. In addition, heavy metals in soil migrate downward due to soil leaching, leading to heavy metal pollution in groundwater. Reducing the hazards of heavy metals in compost will provide a wider space for the rational use of compost.

Most heavy metals are transition elements. In the soil environment, heavy metals will undergo redox reactions within a certain range, and heavy metals with different valence states have different activities and toxicity. Soil heavy metal pollution has the characteristics of wide range, long duration, strong concealment, enrichment through the food chain, difficult treatment, and irreversibility. A large number of biological analysis and toxicology studies have shown that the biological activity, toxicity and migration and transformation process of heavy metal elements in the environment are closely related to their existing forms in the environment. Therefore, it is difficult to indicate the pollution characteristics of heavy metals only by the total amount of heavy metals.

To evaluate the degree of harm of heavy metal pollution to soil and plants, its specific form must be analyzed. The chemical continuous extraction method can be used to extract and separate the heavy metals in different combinations in the soil step by step with high accuracy. Tessier et al. divided the forms of heavy metals in sediments into five types: exchangeable state, carbonate-bound state, iron-manganese oxide-bound state, organic-bound state, and residue state. The European Bureau of Reference and Communication divides the forms of heavy metals into: exchangeable state, reducible state, oxidizable state and residual state, that is, BCR continuous extraction method.

The bioavailable state includes the water-soluble state and the exchanged state. Bioavailable heavy metals in soil have the characteristics of small content, strong mobility, and easy absorption. They are sensitive to environmental changes and can be directly absorbed by plants. They are the main source of soil heavy metal pollution and harmful organisms. Biopotentially available states include carbonate-bound states, iron-manganese oxide-bound states, and organic matter-bound states. In a more acidic medium and under appropriate environmental conditions, they transform into a bioavailable state. Organically bound heavy metals may be converted into active states and released into the environment only in alkaline or oxidizing environments, so they are potentially harmful. Residual heavy metals are not easily released under normal conditions in nature, and can be stable in sediments for a long time, and are not easily absorbed by plants. However, when it encounters strong acid, strong base or chelating agent, these metals are also likely to be activated and released into the environment, posing a threat to the ecosystem. The heavy metal content of this form has minimal effect on the migration and bioavailability of heavy metals in soil.

Heavy metals form different chemical forms in soil and are easily adsorbed by soil media. However, under the influence of various factors, heavy metals will migrate and transform. The migration of heavy metals in soil is a very complex process, which is the result of the joint action of three migration modes: physical migration, physicochemical migration and biological migration, which leads to the unpredictability of heavy metal migration in soil.

When the soil conditions change, the forms of heavy metals in the soil will change accordingly, which is mainly affected by factors such as redox conditions in the soil, additives, and pH value. pH is an important factor affecting the solubility and retention of heavy metals in soil. pH affects the chemical behavior of heavy metals in soil by changing the adsorption sites of heavy metals in soil, the stability of adsorption surface, the existence form and coordination performance. Soil redox potential Eh is one of the key factors affecting the behavior of heavy metal elements. Studies have shown that with the gradual increase of Eh, the exchange state and carbonate binding state of Cu, Zn and Pb gradually increase, while the oxide binding state Cu increases and Pb decreases. In addition, the distribution of heavy metals in soil varies with different crops. The crop cultivation environment has an important influence on the form of heavy metals, mainly due to the existence of plant root secretion, the pH, Eh, and microorganisms in the rhizosphere of crops constitute a special habitat different from that in the non-rhizosphere, which makes heavy metals in the rhizosphere and non-rhizosphere. The content and distribution of each chemical form in the rhizosphere environment are also different. Changes in the rhizosphere regulate the absorption of heavy metals by plants to a certain extent. The soluble Cu in rhizosphere soil is higher than that in non-rhizosphere soil, and rhizosphere exudates can complex with heavy metals and migrate heavy metals to them.

There are three ways to artificially remediate heavy metal pollution in soil: remove heavy metals in soil, mainly by new soil replacement, plant extraction and other methods; isolate heavy metal pollution; change the existing form of heavy metals to reduce their mobility and bioavailability So that it can exist in the soil stably for a long time, mainly represented by in-situ fixation and microbial remediation.

In situ fixed restoration of heavy metal contaminated soil plays an irreplaceable role in the treatment of contaminated soil. Adding different exogenous substances to the soil can change the chemical form of heavy metals through a series of reactions, reduce their mobility and bioavailability, and reduce the toxicity and migration accumulation of heavy metals. Commonly used soil remediation materials mainly include inorganic substances such as zeolite, vermiculite, lime, phosphate rock, and slag, green manure, organic substances rich in carbon content, and some nanomaterials that can be used to remediate heavy metal pollution. Wu Lieshan et al. carried out rapid passivation treatment of heavy metals in polluted soil, and sorted the passivation capabilities of each passivator and compound combination according to the stability efficiency and the passivation capability value of the passivator. It can be seen that the lime passivation capability value is the largest. , the application of lime can reduce the bioavailability of Cu, Zn, As, Hg, Cd, Pb in soil. Fly ash has strong adsorption performance on Zn and Pb in soil. Yinfei applied four kinds of passivating agents to the heavy metal compound polluted soil, the content of Zn in the exchangeable state and the carbonate-bound state decreased significantly after the treatment of steel slag and phosphate rock powder, and the content of Cu in the residual state was significantly increased by steel slag and phosphate rock powder. After adding phosphate rock powder, the content of calcium-type arsenic, which is difficult for bioabsorption, increases significantly; among them, charcoal and palygorskite are mainly based on the passivation adsorption and complexation of heavy metals, and the repair mechanism of steel slag and phosphate rock powder to heavy metals is mainly chemical precipitation. Mainly. The granular slag and MgO are mixed in proportion to remediate the soil. The slag has good adsorption properties for heavy metals and can effectively improve heavy metal and organic polluted soil. Soares et al. used eggshell compost to adsorb Pb and Zn in the soil. After adding it, the pH value of the soil can be increased, the exchangeable Pb and Zn in the soil can be reduced, and the heavy metals in the soil can be effectively repaired. Using carbon-rich materials such as green manure and manure compost to repair soil together with inorganic acids can effectively reduce the pollution of As and Cu to the soil. The interaction between papermaking sludge and soil can form new adsorption sites, which can help fix Zn in soil, improve soil quality and reduce heavy metal content in seepage fluid. Shaheen used inorganic substances: zeolite, AlO, MnO and carbonates and organic amendments: activated carbon, oil residue compost to fix Cu in soil and grow corn. The results showed that after adding soil remediation agent, the Cu content in corn decreased, and the effect of organic amendments was better than that of inorganic amendments, among which activated carbon and AlO had better effects.

The nanoparticle remediation agent has a huge specific surface area, which has a strong adsorption effect on the polluted heavy metal ions in the soil, and can reduce the migration, transformation and biological availability of heavy metal ions in the polluted soil. Using nano-hydroxyapatite (nHAP) and micro-hydroxyapatite (mHAP) to remediate heavy metal-contaminated soil, they can reduce the bioavailable Pb, Zn, Cu and Cr in the soil, and after adding nanomaterials, Chinese cabbage Metal levels in the body drop. Nano-TiO ₂ photocatalytic materials, nano-zero-valent iron and other nano-materials also play an important role in the soil remediation environment, which can effectively reduce the toxicity of heavy metal ion pollution. Wang Meng studied the effects of nano-remediation agents: hydroxyapatite HAP, red mud RM, Fe ₃ O ₄ , humic acid-Fe ₃ O ₄ on the absorption and transport of Cd in polluted soil through pot experiments. The results showed that the addition of nano-restoratives could significantly increase the biomass of carrot plants and reduce the Cd content of plants, and the Cd concentration decreased with the increase of the addition of the restorative. -Fe ₃ O ₄ >Fe ₃ O ₄ .

Carbon nanomaterials are an important part of the field of nanomaterials, mainly including carbon nanotubes, fullerenes, graphene and their derivatives. Graphene (GE) is a new periodic honeycomb two-dimensional carbonaceous material formed by sp2 hybridized carbon atoms arranged in a hexagonal shape, with unique physical and chemical properties. In 2004, Geim and Novoselov of the Department of Physics and Astronomy at the University of Manchester in the United Kingdom obtained graphene for the first time by exfoliating graphite crystals with tape, and thus won the 2010 Nobel Prize in Physics. The common preparation methods mainly include micromechanical exfoliation method, chemical vapor deposition method, crystal epitaxial growth method, colloidal suspension method and so on. The huge specific surface area of graphene makes it a high-quality adsorbent, and its advantages such as simple adsorption operation and good treatment effect are widely used in water phase environmental pollution restoration, mainly adsorbing two types of pollutants: organic matter and inorganic anions.

Graphene oxide (graphene oxide, GO) is usually obtained from graphite through chemical oxidation and ultrasonic preparation, and graphene oxide is convenient for large-scale production. The commonly used graphite oxidation methods reported so far mainly include Brodie method, Standenmaier method and Hummers method. At the same time, graphene oxide has a large number of oxygen-containing groups such as hydroxyl groups, carboxyl groups, and epoxy groups. It is a hydrophilic substance that can be firmly combined with other polymers to form complexes through the action of functional groups. Therefore, graphene oxide is very suitable for water treatment applications to remove metal and organic pollutants in water.

Carbon nanotubes are a single-layer tubular substance that is rolled into a seamless cylindrical shape by graphite hexagonal network planes or a multi-layer "tubular substance" formed by nesting layers of graphite hexagonal network. Carbon nanotubes are divided into single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs). The diameter of single-walled carbon nanotubes is roughly between 0.4 and 2.5 nm, and the length can reach several microns; multi-walled carbon nanotubes are composed of multiple coaxial SWNTs, and the number of layers can range from two to dozens of layers. The distance between layers is 0.34nm, and the diameter can reach about 100nm. MWNTs are slightly lower than the surface, and have higher chemical activity due to the presence of more defects on the tube wall of MWNTs. Carbon nanotubes contain rich nanoporous structure and huge specific surface area. The structural characteristics determine their physical and chemical properties, mainly in that they have excellent adsorption capacity, special electrical and mechanical properties, and have excellent adsorption capacity.

Graphene, graphene oxide and carbon nanotubes have strong adsorption capacity due to their unique surface structure and huge specific surface area, and exhibit strong adsorption performance for organic and inorganic substances. A large number of studies have shown that carbon nanomaterials have a good adsorption effect for the adsorption of organic pollution, and graphene is used to adsorb formaldehyde, basic dyes, organic compounds containing benzene rings and other pollutants. Graphene oxide prepared by a wet method not only has good mechanical characteristics, but also can effectively adsorb dyes in polluted solutions. There are studies on the adsorption of sulfamethoxazole on graphene-based restorative materials. All materials show strong adsorption capacity, and the maximum adsorption capacity is as follows: graphene (239.0 mg·g ^-1 )> graphene–NH ₂ (40.6 mg g ^-1 ) > graphene–COOH (20.5 mg g ^-1 ) > graphene–OH (11.5 mg g ^-1 ). The repair performance changes with the pH of the environment. When pH=2, its adsorption performance is the strongest, but when pH=9, it loses its adsorption capacity. Farghali et al. used the Hummer method to prepare graphene oxide and reduced it to obtain reduced graphene oxide. They modified redox graphene with CoFe ₂ O ₄ and tested its adsorption effect on methyl green. The results showed that the surface area of graphene reached 40.6m ² /g . In addition, graphene oxide also has a good adsorption effect on other basic dyes. 3DGO biopolymer gel is used to adsorb methylene blue and methyl violet in sewage. Through experimental research, the maximum adsorption capacity of the two is respectively 1100mg/g and 1350mg/g, and has strong selectivity for adsorption.

In conclusion, the current use of graphene, carbon nanotubes and their derivatives in heavy metal adsorption technology is mainly limited to the field of polluted water treatment, but there is no literature report on the application of Cd release power in domestic waste composting matrix.

Carbon nanomaterials have a remarkable effect in the treatment of pollutants due to their large specific surface area, strong chemical stability, and the ability to compound multiple functional groups on the surface. At present, a lot of research is on the adsorption of pollutants in water by carbon nanomaterials, and there are few studies on the remediation of pollutants in colloidal environments such as soil. Moreover, a large number of studies have analyzed the toxic effects of high-concentration carbon nanomaterials on isolated cells, tissues, etc., as well as the impact on plants and microorganisms, indicating that carbon nanomaterials have a significant dose effect, but the application of low-concentration and long-term effects of carbon nanomaterials less. Domestic waste composting has achieved remarkable results in agricultural production and landscaping. If the environmental heavy metal pollution caused by the accumulation of heavy metal content cannot be solved, the widespread use of waste composting will be restricted.

Contents of the invention

The invention mainly adopts carbon nanomaterials to fix and restore heavy metals in domestic garbage composting, and explores the fixing effect of carbon nanomaterials on heavy metals in domestic garbage composting. Carbon nanomaterials were added to the lawn planting compost matrix, and the heavy metal leakage characteristics of the domestic waste compost repaired by carbon nanomaterials were analyzed and determined under simulated artificial acid rain conditions.

In this paper, after using carbon nanomaterials to immobilize heavy metals in domestic waste, simulate the leaching amount and leaching rate of heavy metals under acid rain conditions, and analyze the fitting kinetic curve to explore the leaching of heavy metals in the mixed matrix of carbon nanomaterials domestic waste composting release mechanism. This technology helps to understand the release dynamic characteristics of Cd immobilized by carbon nanomaterials under the action of natural rainfall, and provides technical support for the safe use of garbage composting.

To achieve the above object, the present invention discloses the following technical contents:

A method of using carbon nanomaterials to regulate and control the Cd release power of domestic garbage composting, characterized in that it is performed according to the following steps:

(1) Development materials

The waste compost for test was taken from Tianjin Xiaodian Domestic Waste Compost Treatment Plant, passed through a 2mm sieve for later use; its basic physical and chemical properties are: organic matter content 22.00%, bulk density 0.79g/cm ³ , porosity 67.98%, saturated water content 0.67ml· g ^-1 , pH value 7.49, total nitrogen 0.57%, total phosphorus 0.34%, total potassium 1. 21%, available phosphorus 0.078 g·kg ^-1 , C/N is 8.37, and the metal content is: Ca 23.23 mg/ kg, Fe 30.49 g/kg, Mg 5.78 g/kg, Cu 341.34 mg/kg, Zn 677.33 mg/kg, Pb 216.98 mg/kg, Cd 5.02 mg/kg, Mn 437.88 mg/kg, Cr 702.6 mg/kg kg, Ni 41.82 mg/kg.

Graphene microflakes (Graphene) were purchased from Nanjing Jicang Nano Technology Co., Ltd., black, with irregular thin-sheet structure, microplate size: 0.5-20 μm; microplate thickness: 5-25 nm; specific surface area: 40-60 m ² /g; density: about 2.25 g/cm ³ ; electrical conductivity: 8000-10000 S/m; carbon content: >99.5%.

Graphene oxide (Graphene oxide) was purchased from Suzhou Hengqiu Nano Co., Ltd., it is black or brownish yellow powder, average thickness: 3.4-7 nm; sheet diameter: 10-50 μm; number of layers: 5-10 layers; specific surface area: 100-300 m ² /g; purity >90%.

Carboxylated multi-walled carbon nanotubes (carboxylic multi-walled carbon nanotubes) were purchased from Beijing Boyu High-tech New Material Technology Co., Ltd., diameter: 20-40 nm; length: 10-30 μm; -COOH content: 1.43%; purity: >90 wt%; ashes: <8 wt%; specific surface area: >110 m ² /g; conductivity: >10 ² s/cm.

Hydroxylation multi-walled carbon nanotubes (Hydroxylation multi-walled carbon nanotubes) were purchased from Beijing Boyu Hi-Tech New Material Technology Co., Ltd., diameter: 20-40 nm; length: 10-30 μm; -OH content: 1.63%; purity: >90 wt%; ashes: <8 wt%; specific surface area: >110 m ² /g; conductivity: >10 ² s/cm.

(2) Fill the leaching tube

The leaching pipe is a PVC pipe with a height of 25 cm and an inner diameter of 3 cm. The bottom of the pipe is sealed with gauze. In each column, the bottom layer is filled with 20g of river sand with a height of 1-2cm, and the upper layer is filled with 150g of domestic waste compost and 1% (w/w) Carbon nanomaterial graphene microflakes or 1% (w/w) carbon nanomaterial graphene oxide form a mixed matrix of compost and nanomaterials, set up a control group (CK): no carbon nanomaterials, 4 treatment groups They are: added graphene (G); graphene oxide (GO); hydroxylated multi-walled carbon nanotubes (C-OH) and carboxylated multi-walled carbon nanotubes (C-CH);

(3) Set the shower solution

In this experiment, the concentrations of SO ₂ ^-4 , NO ₃ ^- , Cl ^- , NH ⁺⁴ , Mg ²⁺ , Ca ²⁺ , K ⁺ , and Na ⁺ were respectively 14.96, 6.54, 1.68, 3.71, 0.82, 1.38, 0.64, and 0.78 mg·L ^-1 simulated rainwater, and adjust the pH to 5.6 with HCl;

(4) Leaching test

The leaching tube was left to mature for 30 days, and distilled water was added to the tube every day. The water content of the soil in the tube was the field water holding capacity. During this period, the indoor temperature was 18-25 °C, the relative humidity was 35%-65%, and the light was natural light penetrating into the room. For 30 days, the leaching experiment was carried out. At the beginning of the experiment, simulated rainwater was injected from the top, and the leaching solution flowing out of the lower end of the leaching pipe was collected every 10 ml until the accumulated amount of leaching solution reached 100 ml, and the time was recorded. A spectrophotometer was used to measure the concentration of heavy metal Cd.

The invention further discloses the application of the method of using carbon nanometer material to control the Cd release power of domestic waste composting in improving the dynamic fitting degree of Cd. Especially to reduce the application of remediation domestic waste composting in simulating the leakage characteristics of heavy metals under artificial acid rain conditions.

The present invention is described in more detail as follows:

1 Development materials and methods

1.1 Development materials

The waste compost for testing was taken from Tianjin Xiaodian Household Waste Composting Plant and passed through a 2mm sieve for later use. Its basic physical and chemical properties are: organic matter content 22.00%, bulk density 0.79g/cm ³ , porosity 67.98%, saturated water content 0.67ml·g ^-1 , pH value 7.49, total nitrogen 0.57%, total phosphorus 0.34%, total potassium 1 . 21%, available phosphorus 0.078 g·kg ^-1 , C/N is 8.37, and the metal contents are: Ca 23.23 mg/kg, Fe 30.49 g/kg, Mg 5. 78 g/kg, Cu 341.34 mg/kg , Zn 677.33 mg/kg, Pb 216.98 mg/kg, Cd 5.02 mg/kg, Mn 437.88 mg/kg, Cr 702.6 mg/kg, Ni 41.82 mg/kg.

Graphene microflakes (Graphene) were purchased from Nanjing Jicang Nano Technology Co., Ltd., black, with irregular thin-sheet structure, microplate size: 0.5-20 μm; microplate thickness: 5-25 nm; specific surface area: 40-60 m ² /g; density: about 2.25 g/cm ³ ; electrical conductivity: 8000-10000 S/m; carbon content: >99.5%.

Graphene oxide (Graphene oxide) was purchased from Suzhou Hengqiu Nano Co., Ltd., it is black or brownish yellow powder, average thickness: 3.4-7 nm; sheet diameter: 10-50 μm; number of layers: 5-10 layers; specific surface area: 100-300 m ² /g; purity >90%.

Carboxylated multi-walled carbon nanotubes (carboxylic multi-walled carbon nanotubes) were purchased from Beijing Boyu High-tech New Material Technology Co., Ltd., diameter: 20-40 nm; length: 10-30 μm; -COOH content: 1.43%; purity: >90 wt%; ashes: <8 wt%; specific surface area: >110 m ² /g; conductivity: >10 ² s/cm.

Hydroxylation multi-walled carbon nanotubes (Hydroxylation multi-walled carbon nanotubes) were purchased from Beijing Boyu Hi-Tech New Material Technology Co., Ltd., diameter: 20-40 nm; length: 10-30 μm; -OH content: 1.63%; purity: >90 wt%; ashes: <8 wt%; specific surface area: >110 m ² /g; conductivity: >10 ² s/cm.

1.2 Filling the leaching tube

The leaching pipe is a PVC pipe with a height of 25 cm and an inner diameter of 3 cm, and the bottom of the pipe is sealed with gauze. In each column, the bottom layer is filled with 20g of river sand with a height of about 1cm, and the upper layer is filled with 150g of domestic waste compost and 1% carbon nanomaterial mixed matrix. Set up a control group (CK): without adding carbon nanomaterials, and the four treatment groups are: adding graphene (G); graphene oxide (GO); hydroxylated multi-walled carbon nanotubes (C-OH) and carboxyl Multi-walled carbon nanotubes (C-CH), and the experiment was repeated three times.

1.3 Setting up the shower solution

The annual rainfall in Tianjin is about 550 mm. According to the statistics of June-September rainfall in Tianjin from 2011 to 2013, the longest rainfall time is 15 hours, and the hourly rainfall reaches 16 mm. soil. This experiment simulates the leaching of summer torrential rain. According to the pH survey of precipitation in Tianjin, it is acidic precipitation with an annual average pH of 5.6. In this experiment, the concentrations of SO ₂ ^-4 , NO ₃ ^- , Cl ^- , NH ⁺⁴ , Mg ²⁺ , Ca ²⁺ , K ⁺ , and Na ⁺ were respectively 14.96, 6.54, 1.68, 3.71, 0.82, 1.38, 0.64, and 0.78 mg·L ^-1 simulated rainwater, and adjust the pH to 5.6 with HCl.

1.4 Leaching test

The leaching tube was allowed to stand and mature for 30 days, and an appropriate amount of distilled water was added to the tube every day, and the water content of the soil in the tube was the field water capacity. During this period, the indoor temperature is 18-25 ℃, the relative humidity is 35%-65%, and the light is natural light (6856LX-27090LX) penetrating into the room. On the 30th day, the leaching experiment was carried out. At the beginning of the experiment, simulated rainwater was injected from the top. The leach solution flowing from the lower end of the leaching pipe is collected every 10 ml until the accumulated amount of the leach solution reaches 100 ml, and the time is recorded. The concentration of heavy metal Cd in the leach solution was determined by an atomic absorption spectrophotometer (TAS-990).

1.5 Data processing

Soil Dynamics Model:

Elovich equation: Q=aln(t)+b

Double constant equation: Q=bt ^a

In the formula: Q is the cumulative release of heavy metals in the soil under the simulated artificial acid rain (mg kg ^-1 ); t is the leaching time (min); a and b are constants, a represents the release rate of heavy metals, and the smaller a is The release rate of heavy metals decreased faster.

The processed data was fitted with the adsorption kinetic curve using Origin 8.6.

2 Analysis of development results

During the long-term research process, researchers have proposed many soil dynamic models to simulate the whole experimental process, among which the first-order kinetic equation, second-order kinetic equation, Elovich equation, power function equation, double constant rate equation, etc. are common. Fitting the experimental data according to these equations can approximate the change law of the whole adsorption process. According to the fitting calculation of the experimental results, the double constant and Elovich equations have higher fitting degrees, and the other equations have lower fitting degrees.

The fitting curve and fitting results of Cd release kinetics under artificial acid rain leaching are shown below. As shown in the kinetic fitting results of Cd (Table 1), the fitting degree of the control group and the double-constant equation is high. After adding carbon nanomaterials, the fitting degree of the homogeneous and double-constant equation is higher than that of the Elovich equation.

Table 1 Fitting parameters of Cd release kinetics

3. Development conclusion

The kinetic fitting results of Cd showed that the fitting degree of the control group and the double constant equation was high, and after adding carbon nanomaterials, the fitting degree of the mean and double constant equation was higher than that of the Elovich equation.

detailed description

The present invention is described below through specific embodiments. Unless otherwise specified, the technical means used in the present invention are methods known to those skilled in the art. In addition, the embodiments should be considered as illustrative rather than limiting the scope of the invention, the spirit and scope of which is defined only by the claims. For those skilled in the art, on the premise of not departing from the spirit and scope of the present invention, various changes or modifications to the material components and dosage in these embodiments also belong to the protection scope of the present invention. The raw materials and reagents used in the present invention are commercially available.

Example 1

(1) Development materials

The waste compost for test was taken from Tianjin Xiaodian Domestic Waste Compost Treatment Plant, passed through a 2mm sieve for later use; its basic physical and chemical properties are: organic matter content 22.00%, bulk density 0.79g/cm ³ , porosity 67.98%, saturated water content 0.67ml· g ^-1 , pH value 7.49, total nitrogen 0.57%, total phosphorus 0.34%, total potassium 1. 21%, available phosphorus 0.078 g·kg ^-1 , C/N is 8.37, and the metal content is: Ca 23.23 mg/ kg, Fe 30.49 g/kg, Mg 5.78 g/kg, Cu 341.34 mg/kg, Zn 677.33 mg/kg, Pb 216.98 mg/kg, Cd 5.02 mg/kg, Mn 437.88 mg/kg, Cr 702.6 mg/kg kg, Ni 41.82 mg/kg.

Graphene microflakes (Graphene) were purchased from Nanjing Jicang Nano Technology Co., Ltd., black, with irregular flake-like structure, the size of the flakes: 10 μm; the thickness of the flakes: 50 nm; the specific surface area: 400 m ² /g; the density : about 2.25 g/cm ³ ; electrical conductivity: 80000 S/m; carbon content: >99.5%.

Graphene oxide (Graphene oxide) was purchased from Suzhou Hengqiu Nano Co., Ltd., which is black or brown-yellow powder, average thickness: 3.40 nm; sheet diameter: 100 μm; layer number: 50 layers; specific surface area: 1000 m ² /g; purity >90%.

Carboxylated multi-walled carbon nanotubes (carboxylic multi-walled carbon nanotubes) were purchased from Beijing Boyu High-tech New Material Technology Co., Ltd., diameter: 20-40 nm; length: 10-30 μm; -COOH content: 1.43%; purity: >90 wt%; ashes: <8 wt%; specific surface area: >110 m ² /g; conductivity: >10 ² s/cm.

Hydroxylation multi-walled carbon nanotubes (Hydroxylation multi-walled carbon nanotubes) were purchased from Beijing Boyu Hi-Tech New Material Technology Co., Ltd., diameter: 20-40 nm; length: 10-30 μm; -OH content: 1.63%; purity: >90 wt%; ashes: <8 wt%; specific surface area: >110 m ² /g; conductivity: >10 ² s/cm.

(2) Fill the leaching tube

The leaching pipe is a PVC pipe with a height of 25 cm and an inner diameter of 3 cm. The bottom of the pipe is sealed with gauze. In each column, the bottom layer is filled with 20g of river sand with a height of 1-2cm, and the upper layer is filled with 150g of domestic waste compost and 1% (w/w) Carbon nanomaterial graphene microflakes or 1% (w/w) carbon nanomaterial graphene oxide form a mixed matrix of compost and nanomaterials, set up a control group (CK): no carbon nanomaterials, 4 treatment groups They are: added graphene (G); graphene oxide (GO); hydroxylated multi-walled carbon nanotubes (C-OH) and carboxylated multi-walled carbon nanotubes (C-CH);

(3) Set the shower solution

In this experiment, the concentrations of SO ₂ ^-4 , NO ₃ ^- , Cl ^- , NH ⁺⁴ , Mg ²⁺ , Ca ²⁺ , K ⁺ , and Na ⁺ were respectively 14.96, 6.54, 1.68, 3.71, 0.82, 1.38, 0.64, and 0.78 mg·L ^-1 simulated rainwater, and adjust the pH to 5.6 with HCl;

(4) Leaching test

The leaching tube was left to mature for 30 days, and distilled water was added to the tube every day. The water content of the soil in the tube was the field water holding capacity. During this period, the indoor temperature was 180 ° C, the relative humidity was 35%, and the light was natural light penetrating into the room. On the 30th day, the leaching For the dissolution test, at the beginning of the experiment, simulated rainwater was injected from the top, and the leaching solution flowing out of the lower end of the leaching pipe was collected every 10 ml until the cumulative amount of the leaching solution reached 100 ml, and the time was recorded. The leaching solution was measured with an atomic absorption spectrophotometer. Concentration of heavy metal Cd.

Example 2

(1) Development materials

The waste compost for test was taken from Tianjin Xiaodian Domestic Waste Compost Treatment Plant, passed through a 2mm sieve for later use; its basic physical and chemical properties are: organic matter content 22.00%, bulk density 0.79g/cm ³ , porosity 67.98%, saturated water content 0.67ml· g ^-1 , pH value 7.49, total nitrogen 0.57%, total phosphorus 0.34%, total potassium 1. 21%, available phosphorus 0.078 g·kg ^-1 , C/N is 8.37, and the metal content is: Ca 23.23 mg/ kg, Fe 30.49 g/kg, Mg 5.78 g/kg, Cu 341.34 mg/kg, Zn 677.33 mg/kg, Pb 216.98 mg/kg, Cd 5.02 mg/kg, Mn 437.88 mg/kg, Cr 702.6 mg/kg kg, Ni 41.82 mg/kg.

Graphene microflakes (Graphene) were purchased from Nanjing Jicang Nano Technology Co., Ltd., black, with irregular thin-sheet structure, microplate size: 20 μm; microplate thickness: 25 nm; specific surface area: 60 m ² /g; density : about 2.25 g/cm ³ ; electrical conductivity: 10000 S/m; carbon content: >99.5%.

Graphene oxide (Graphene oxide) was purchased from Suzhou Hengqiu Nano Co., Ltd., which is black or brown-yellow powder, average thickness: 7 nm; sheet diameter: 50 μm; number of layers: 10 layers; specific surface area: 300 m ² /g; Purity>90%.

(2) Fill the leaching tube

The leaching pipe is a PVC pipe with a height of 25 cm and an inner diameter of 3 cm. The bottom of the pipe is sealed with gauze. In each column, the bottom layer is filled with 20g of river sand with a height of 1-2cm, and the upper layer is filled with 150g of domestic waste compost and 1% (w/w) Carbon nanomaterial graphene microflakes or 1% (w/w) carbon nanomaterial graphene oxide form a mixed matrix of compost and nanomaterials, set up a control group (CK): no carbon nanomaterials, 4 treatment groups They are: added graphene (G); graphene oxide (GO); hydroxylated multi-walled carbon nanotubes (C-OH) and carboxylated multi-walled carbon nanotubes (C-CH);

(3) Set the shower solution

In this experiment, the concentrations of SO ₂ ^-4 , NO ₃ ^- , Cl ^- , NH ⁺⁴ , Mg ²⁺ , Ca ²⁺ , K ⁺ , and Na ⁺ were respectively 14.96, 6.54, 1.68, 3.71, 0.82, 1.38, 0.64, and 0.78 mg·L ^-1 simulated rainwater, and adjust the pH to 5.6 with HCl;

(4) Leaching test

The leaching tube was left to mature for 30 days, and distilled water was added to the tube every day. The water content of the soil in the tube was the field water holding capacity. During this period, the indoor temperature was 25 °C, the relative humidity was 65%, and the light was natural light penetrating into the room. For the dissolution test, at the beginning of the experiment, simulated rainwater was injected from the top, and the leaching solution flowing out of the lower end of the leaching pipe was collected every 10 ml until the cumulative amount of the leaching solution reached 100 ml, and the time was recorded. The leaching solution was measured with an atomic absorption spectrophotometer. Concentration of heavy metal Cd.

Claims (4)

1. the method using carbon nanomaterial regulation and control consumer garbage compost Cd release power, it is characterised in that by following step Suddenly carry out:

(1) material is developed

Take from Tianjin little Dian consumer garbage compost treatment plant for examination garbage compost, cross 2mm sieve standby；

Graphene microchip flit size: 0.5-20 μm；Microplate thickness: 5-25 nm；Specific surface area: 40-60 m2/g；Density: about 2.25 g/cm3；Electrical conductivity: 8000-10000 S/m；Phosphorus content: > 99.5%；

Graphene oxide average thickness: 3.4-7 nm；Lamella diameter: 10-50 μm；The number of plies: 5-10 layer；Specific surface area: 100- 300 m2/g；Purity > 90%；

(2) leaching pipe is loaded

Leaching Guan Weigao 25 cm, the pvc pipe of internal diameter 3 cm, use gauze back cover at the bottom of pipe, in each post, it is high that river sand 20g filled by bottom Degree 1-2cm, 150g consumer garbage compost and 1%(w/w are filled in upper strata) carbon nanomaterial graphene microchip or 1%(w/w) carbon nanometer Material oxidation Graphene, forms compost and the mixed-matrix of nano material, arranges 1 matched group (CK): without carbon nanometer material Material, 4 process groups are respectively as follows: interpolation Graphene (G)；Graphene oxide (GO)；Hydroxylating multi-walled carbon nano-tubes (C-OH) and carboxylic Base multi-walled carbon nano-tube (C-CH)；

(3) leaching liquor is set

This experimental formula SO₂ ^-4、NO₃ ^-、Cl^-、NH⁺⁴、Mg²⁺、Ca²⁺、K⁺、Na⁺Concentration is respectively 14.96,6.54,1.68,3.71, 0.82、1.38、0.64、0.78 mg·L^-1Simulated rainwater, and with HCl adjust pH be 5.6；

(4) leaching test

Leaching pipe stands ripening 30 days, adds distilled water in giving pipe every day, and in pipe, soil moisture content is field capacity, period, Indoor temperature 18～25 DEG C, relative humidity 35%～65%, illumination is the natural light penetrating indoor, the 30th day, carries out leaching real Testing, when experiment starts, inject Simulated rainwater from top, every 10 ml of leaching liquor that leaching pipe lower end is flowed out gather once, until drenching Solution cumulant reaches 100 ml, and records the time, and leaching liquor atomic absorption spectrophotometer measures wherein heavy metal Cd Concentration.

2. the method described in claim 1, wherein said little shallow lake its basic physical and chemical of consumer garbage compost is: basic physics and chemistry Character is: the content of organic matter 22.00%, unit weight 0.79g/cm³, porosity 67.98%, saturation moisture content 0.67ml g^-1, pH value 7.49, full nitrogen 0.57%, full phosphorus 0.34%, full potassium 1. 21%, available phosphorus 0.078 g kg^-1, C/N is 8.37, wherein metal Content is respectively as follows: Ca 23.23 mg/kg, Fe 30.49 g/kg, Mg 5. 78 g/kg, Cu 341.34 mg/kg, Zn 677.33 mg/kg, Pb 216.98 mg/kg, Cd 5.02 mg/kg, Mn 437.88 mg/kg, Cr 702.6 mg/kg, Ni 41.82 mg/kg；

The size of graphene microchip: 0.5-20 μm；Microplate thickness: 5-25 nm；Specific surface area: 40-60 m²/g；Density: about 2.25 g/cm³；Electrical conductivity: 8000-10000 S/m；Phosphorus content: > 99.5%；

The average thickness of graphene oxide: 3.4-7 nm；Lamella diameter: 10-50 μm；The number of plies: 5-10 layer；Specific surface area: 100- 300 m²/g；Purity > 90%.

3. the method using carbon nanomaterial regulation and control consumer garbage compost Cd release power described in claim 1 is improving the dynamic of Cd Application in terms of mechanics degree of fitting.

4. described in claim 1, use the method for carbon nanomaterial regulation and control consumer garbage compost Cd release power after reducing reparation Consumer garbage compost in the application of the heavy metal leakage characteristic aspect simulated under the conditions of artificial acid rain.