Experimental modeling method for diffusion process of heavy metal ions in soil

Abstract

In order to overcome the technical problem that the diffusion condition of heavy metal ions in soil along with the change of environmental conditions and time cannot be detected, the invention provides an experimental modeling method for the diffusion process of the heavy metal ions in the soil. The filled to-be-studied soil is equivalent to the soil condition of a remediation site with a certain depth, a plurality of sealed sampling test ports are formed in the cylinder, an artificial channel port capable of sampling is established, heavy metal ion sample soil with different depths is collected at different time and different positions to obtain data, and meanwhile, the sampling test port is used for sampling the heavy metal ion sample soil. And providing a candidate model of soil heavy metal ion diffusion, providing error description according to the obtained data, and determining the model through a system identification method and applying the model to prediction and estimation of heavy metal ion distribution.

Description

Technical Field

[0001] This invention relates to methods for heavy metal ions, and particularly to experimental modeling methods for the diffusion process of heavy metal ions in soil, belonging to the fields of soil pollution remediation and ecological environmental protection. Background Technology

[0002] Heavy metals mainly refer to mercury, cadmium, lead, chromium, heavy metals emitted from nuclear power plants, and metalloid arsenic, which are highly toxic to organisms. They also include toxic heavy metals such as zinc, copper, cobalt, nickel, tin, and vanadium.

[0003] Heavy metal pollution mainly originates from industrial wastewater (arbitrary discharge of pollutants from industries such as metallurgy, chemicals, electroplating, and printing and dyeing). Subsequently, heavy metals migrate between water and soil, affecting agricultural environmental safety and the quality and safety of agricultural products, and even endangering human health and survival.

[0004] According to data from the National Bureau of Statistics, more than 20 million hectares of land nationwide are contaminated with heavy metals, of which more than 700,000 hectares are severely polluted, and more than 130,000 hectares of land have been abandoned due to excessive cadmium content. Currently, more than 63% of lakes nationwide are polluted, and more than 33% are no longer potable. Therefore, how to solve the problem of heavy metal ion treatment in in-situ site remediation is of great significance. To date, factories and researchers from various industries have made great efforts to treat soil and wastewater pollution.

[0005] Metallurgical pollution control is a key and challenging issue in current metallurgical research. The three wastes of metallurgy are a key focus of current green metallurgical research, and the emission of heavy metal ions from these three wastes is a hot topic and a major challenge both domestically and internationally. Heavy metal ions are characterized by high toxicity, high stability, and high bioaccumulation, making them difficult to eliminate through natural degradation or dilution. Therefore, finding effective technologies for removing heavy metal ions from wastewater is an important research topic. However, the problem of heavy metal ion treatment in in-situ site remediation remains unsolved.

[0006] Existing research mainly focuses on three approaches, each with its own limitations. Physicochemical methods primarily include solidification / stabilization remediation technology and soil leaching remediation technology, while biological methods mainly include microbial remediation, phytoremediation, and agroecological remediation. Physical methods typically use adsorption and precipitation to remove stable substances, but their main problem lies in their poor effectiveness against heavy metal ions. Chemical methods typically use chemical agents to passivate and separate substances through chemical reactions; however, current heavy metal ion monitoring cannot provide real-time online indicators, especially regarding the diffusion of heavy metal ions in soil under changing environmental conditions and time. This makes it difficult to accurately quantify chemical agents, easily leading to incomplete treatment or secondary pollution. Biological methods mainly utilize the biological characteristics of plants / microorganisms, using the adsorption of heavy metal ions to enrich them within the organism, thereby treating soil pollutants. While this method solves the secondary pollution problem of chemical methods, it currently has a long treatment cycle and requires a large area, failing to meet the demands of efficient and economical industrial production processes. Summary of the Invention

[0007] To overcome the technical problem of undetectable diffusion of heavy metal ions in soil under varying environmental conditions and time, this invention provides an experimental modeling method for the diffusion process of heavy metal ions in soil. This method establishes an equivalent experimental setup for the diffusion process of heavy metal ions in soil. The soil sampled is equivalent to the soil at a certain depth in a remediation site. Multiple sealed sampling ports are set up on a cylinder, and an artificial sampling channel is established. Soil samples of heavy metal ions at different times, locations, and depths are collected to obtain data. Simultaneously, candidate models for the diffusion of heavy metal ions in soil are provided. An error description is given based on the acquired data. A systematic identification method is used to determine the model and apply it to the prediction and estimation of heavy metal ion distribution.

[0008] The technical solution adopted by this invention to solve its technical problem is: an experimental modeling method for the diffusion process of heavy metal ions in soil, characterized by the following features:

[0009] Step 1: Establish an equivalent experimental device for the diffusion process of heavy metal ions in soil. The basic structure of this equivalent experimental device consists of two concentric hollow cylinders of similar height and different large radii, which can be below ground level or partially above ground level. The outer hollow cylinder has thermal insulation properties, while the inner hollow cylinder has good thermal conductivity. The two cylinders are equipped with a temperature control function that distributes according to their height. The hollow part of the inner hollow cylinder is filled with the soil of the site whose heavy metal ion content has been detected. The soil to be studied is equivalent to the soil conditions at a certain depth. At a designated position at the top of the equivalent experimental device, a pollution source containing the heavy metal ions to be studied is simulated or a treatment liquid such as ozone water is injected. Multiple sealed sampling test ports are set on the cylinders, and an artificial channel is set up to facilitate the collection of soil samples containing heavy metal ions at different depths.

[0010] Step 2: Let r = [xyz] T x, y, z are the coordinate values ​​of a three-axis rectangular coordinate system with the central axis of the concentric hollow cylinder as the z-axis, pointing upwards, and the center of the top as the origin. The z-coordinates of all sealed sampling test ports and the x and y coordinates at different positions are known. At the k-th sealed sampling test port, with coordinates r k,i,t =[x k,i,t y k,i,t z k,i,t ] T Sampling was performed at the i-th location according to time points t = T, 2T, ..., LT, and the content q of the heavy metal ions to be detected was obtained using a soil heavy metal ion analyzer. ki (r k,i,t ,t),t=T,2T,…,LT,k=1,2,…,N,i=1,2,…,M k N≥1 represents the number of sealed sampling test ports set up on the cylinder, M k ≥3 is an integer, L>10 is an integer; the obtained array is

[0011]

[0012] Step 3: Establish candidate continuous diffusion models for one heavy metal ion among zinc, copper, cobalt, nickel, tin, vanadium, mercury, cadmium, lead, chromium, heavy metals emitted from nuclear power plants, and metalloid arsenic ions:

[0013]

[0014] In the formula, q(r,t) represents a specific heavy metal ion to be detected, such as zinc, copper, cobalt, nickel, tin, vanadium, mercury, cadmium, lead, chromium, heavy metals emitted from nuclear power plants, and metalloid arsenic ions. K q (r,t) is the 3×3 coefficient matrix corresponding to the heavy metal ion q(r,t), f q(rt) is the 3×1 function vector corresponding to the heavy metal ion q(r,t).

[0015]

[0016] d qxx (r,t),d qxy (r,t),d qxz (r,t),d qyx (r,t),d qyy (r,t),d qyz (r,t),d qzx (r,t),d qzy (r,t),d qzz (r,t) is the coefficient corresponding to the heavy metal ion q(r,t); u(r0,t) is the simulated input of the pollution source containing the heavy metal ion to be studied at the top of the equivalent experimental device, and r0 is the coordinate of the simulated input of the pollution source containing the heavy metal ion to be studied.

[0017] Step 4: Define the error e(r) k,i,t ,t)=q ki (r k,i,t ,t)-q p (r k,i,t ,t),i=1,2,…,M k k = 1, 2, ..., N, t = T, 2T, ..., LT, where q ki (r k,i,t ,t) represents the measured value of the heavy metal ion content to be detected obtained using a soil heavy metal ion analyzer according to step two, and q represents the measured value of the heavy metal ion content to be detected. p (r k,i,t ,t) represents the predicted content of the heavy metal ions to be detected, obtained according to equation (1), corresponding to the time, coordinate position, and measurement sequence, where i = 1, 2, ..., M i ,k=1,2,…,N,t=T,2T,…,LT;

[0018] Define the error vector:

[0019]

[0020] Assume that the coefficient functions are all composed of known functions and unknown parameter vectors: Where, p iLet i = 1, 2, ..., 11 be the vector of unknown parameters, and write it in the form of a global vector of unknown parameters.

[0021] Based on the index w = ψ(e), such that the index can be taken as w = e T Ωe and Ω are weighted matrices, so we can obtain: p = A -1 b, where: It can be by Solve

[0022] Step 5: Based on the obtained p, solve q(r,t) according to equation (1). For a given time t and coordinate position r, the content of heavy metal ions to be detected qp(r,t) can be estimated.

[0023] The beneficial effects of this invention are: the established equivalent experimental device for the diffusion process of heavy metal ions in soil can equivalently simulate the diffusion of heavy metal ions at different depths. Multiple sealed sampling ports are set up on the cylinder, and an artificial sampling channel is established to facilitate the collection of soil samples containing heavy metal ions at different depths. Simultaneously, candidate models for the diffusion of heavy metal ions in soil are provided, and error descriptions are given based on the acquired data. The model is determined through a systematic identification method and used for the prediction and estimation of heavy metal ion distribution.

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0025] Figure 1 A schematic diagram of an equivalent experimental setup for the diffusion process of heavy metal ions in soil. Detailed Implementation

[0026] Reference Figure 1

[0027] Step 1: Establish an equivalent experimental device for the diffusion process of heavy metal ions in soil. The basic structure of this equivalent experimental device consists of two underground concentric hollow cylinders: one with an inner diameter of 5.5 meters and a height of 6 meters, and the other with an outer diameter of 5.03 meters, an inner diameter of 5 meters, and a height of 5.5 meters. The outer hollow cylinder with an inner diameter of 5.5 meters is constructed of fire-resistant, waterproof, and corrosion-resistant materials. Seamless steel pipes form the inner hollow cylinder and have good thermal conductivity. The two cylinders have a temperature control function that distributes according to height. The hollow part of the inner hollow cylinder is filled with the soil of the site whose heavy metal ion content has been tested. The soil to be studied is equivalent to the soil conditions at a certain depth. At a designated position at the top of the equivalent experimental device, a pollution source containing the heavy metal ions to be studied is simulated or a treatment liquid such as ozone water is injected. Multiple sealed sampling test ports are set on the cylinder, and an artificial sampling channel is established to facilitate the collection of soil samples with heavy metal ions at different depths.

[0028] Step 2: Let r = [xyz] T x, y, z are the coordinate values ​​of a three-axis rectangular coordinate system with the central axis of the concentric hollow cylinder as the z-axis, pointing upwards, and the center of the top as the origin. The z-coordinates of all sealed sampling test ports and the x and y coordinates at different positions are known. At the k-th sealed sampling test port, with coordinates r k,i,t =[x k,i,t y k,i,t z k,i,t ] T Sampling was performed at the i-th location according to time points t = T, 2T, ..., LT, and the content q of the heavy metal ions to be detected was obtained using a soil heavy metal ion analyzer. ki (r k,i,t ,t),t=T,2T,…,LT,k=1,2,…,N,i=1,2,…,M k N≥1 represents the number of sealed sampling test ports set up on the cylinder, M k ≥3 is an integer, L>10 is an integer; the obtained array is

[0029]

[0030] Step 3: Establish candidate continuous diffusion models for one heavy metal ion among zinc, copper, cobalt, nickel, tin, vanadium, mercury, cadmium, lead, chromium, heavy metals emitted from nuclear power plants, and metalloid arsenic ions:

[0031]

[0032] In the formula, q(r,t) represents a specific heavy metal ion to be detected, such as zinc, copper, cobalt, nickel, tin, vanadium, mercury, cadmium, lead, chromium, heavy metals emitted from nuclear power plants, and metalloid arsenic ions. K q(r,t) is the 3×3 coefficient matrix corresponding to the heavy metal ion q(r,t), f q (rt) is the 3×1 function vector corresponding to the heavy metal ion q(r,t).

[0033]

[0034] d qxx (r,t),d qxy (r,t),d qxz (r,t),d qyx (r,t),d qyy (r,t),d qyz (r,t),d qzx (r,t),d qzy (r,t),d qzz (r,t) is the coefficient corresponding to the heavy metal ion q(r,t); u(r0,t) is the simulated input of the pollution source containing the heavy metal ion to be studied at the top of the equivalent experimental device, and r0 is the coordinate of the simulated input of the pollution source containing the heavy metal ion to be studied.

[0035] Step 4: Define the error e(r) k,i,t ,t)=q ki (r k,i,t ,t)-q p (r k,i,t ,t),i=1,2,…,M k k = 1, 2, ..., N, t = T, 2T, ..., LT, where q ki (r k,i,t ,t) represents the measured value of the heavy metal ion content to be detected obtained using a soil heavy metal ion analyzer according to step two, and q represents the measured value of the heavy metal ion content to be detected. p (r k,i,t ,t) represents the predicted content of the heavy metal ions to be detected, obtained according to equation (1), corresponding to the time, coordinate position, and measurement sequence, where i = 1, 2, ..., M i ,k=1,2,…,N,t=T,2T,…,LT;

[0036] Define the error vector:

[0037]

[0038] Assume that the coefficient functions are all composed of known functions and unknown parameter vectors: Where, p i ,i=1,2,…,11 are unknown parameters, function K q (r,t) can be:

[0039]

[0040] function f q (r,t) can be:

[0041] D q The coefficient function d in the (r,t) matrix qλμ (r, t), λ = x, y, z, μ = x, y, z, can be

[0042] Based on the index w = ψ(e), such that the index can be taken as w = e T Ωe and Ω are weighted matrices, so we can obtain: p = A -1 b, where: It can be by Solve

[0043] Step 5: Based on the obtained p, solve q(r,t) according to equation (1). For a given time t and coordinate position r, the content of heavy metal ions to be detected q can be estimated. p (r,t).

Claims

1. An experimental modeling method for the diffusion process of heavy metal ions in soil, characterized by including: The following characteristics: Step 1: Establish an equivalent experimental device for the diffusion process of heavy metal ions in soil. The basic structure of this equivalent experimental device consists of two concentric hollow cylinders of similar height and different large radii, which can be below ground level or partially above ground level. The outer hollow cylinder has thermal insulation properties, while the inner hollow cylinder has good thermal conductivity. The two cylinders are equipped with a temperature control function that distributes according to their height. The hollow part of the inner hollow cylinder is filled with the soil of the site whose heavy metal ion content has been detected. The soil to be studied is equivalent to the soil conditions at a certain depth. At a designated position at the top of the equivalent experimental device, a pollution source containing the heavy metal ions to be studied is simulated or a treatment liquid such as ozone water is injected. Multiple sealed sampling test ports are set on the cylinders, and an artificial channel is set up to facilitate the collection of soil samples containing heavy metal ions at different depths. Step 2: Let r = [xyz] T x, y, z are the coordinate values ​​of a three-axis rectangular coordinate system with the central axis of the concentric hollow cylinder as the z-axis, pointing upwards, and the center of the top as the origin. The z-coordinates of all sealed sampling test ports and the x and y coordinates at different positions are known. At the k-th sealed sampling test port, with coordinates r k，i，t =[x k，i，t y k，i，t z k，i，t ] T Sampling was performed at the i-th location according to time points t = T, 2T, ..., LT, and the content q of the heavy metal ions to be detected was obtained using a soil heavy metal ion analyzer. ki (r k，i , t, t), t=T, 2T,..., LT, k=1, 2,..., N, i=1, 2,..., M k N≥1 represents the number of sealed sampling test ports set up on the cylinder, M k ≥3 is an integer, L>10 is an integer; the obtained array is Step 3: Establish candidate continuous diffusion models for one heavy metal ion among zinc, copper, cobalt, nickel, tin, vanadium, mercury, cadmium, lead, chromium, heavy metals emitted from nuclear power plants, and metalloid arsenic ions: In the formula, q(r,t) represents a specific heavy metal ion to be detected, such as zinc, copper, cobalt, nickel, tin, vanadium, mercury, cadmium, lead, chromium, heavy metals emitted from nuclear power plants, and metalloid arsenic ions; K q (r, t) is the 3×3 coefficient matrix corresponding to the heavy metal ion q(r, t), f q (rt) is the 3×1 function vector corresponding to the heavy metal ion q(r,t). d qxx (r, t), d qxy (r, t), d qxz (r, t), d qyx (r, t), d qyy (r, t), d qyz (r, t), d qzx (r, t), d qzy (r, t), d qzz (r, t) is the coefficient corresponding to the heavy metal ion q(r, t); u(r0, t) is the simulated input of the pollution source containing the heavy metal ion to be studied at the top of the equivalent experimental device, and r0 is the coordinate of the simulated input of the pollution source containing the heavy metal ion to be studied. Step 4: Define the error e(r k，i，t ,t)=q ki (r k，i，t ,t)-q p (r k，i，t ,t),i=1,2,…,M k ,k=1,2,…,N,t=T,2T,…,LT, Where q ki (r k，i，t q) represents the measured value of the heavy metal ion content to be detected obtained using a soil heavy metal ion analyzer according to step two. p (r k，i，t ,t) is the predicted value of the content of the heavy metal ions to be detected, obtained according to equation (1), corresponding to the time, coordinate position and measurement sequence, i = 1, 2, ..., M i ,k=1,2,…,N,t=T,2T,…,LT; Define the error vector: Assume that the coefficient functions are all composed of known functions and unknown parameter vectors: Where, p i Let i = 1, 2, ..., 11 be the vector of unknown parameters, and write it in the form of a global vector of unknown parameters. Based on the index W = ψ(e), such that the index can be taken as w = e T Ωe and Ω are weighted matrices, so we can obtain: p = A -1 b, where: It can be by Solve Step 5: Based on the obtained p, solve q(r, t) according to equation (1). For a given time t and coordinate position r, the content of heavy metal ions to be detected q can be estimated. p (r, t).

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