Colloid DLVO theory-based flocculation sediment particle spacing calculation method

Abstract

The invention relates to a flocculation sediment particle spacing calculation method based on a colloid DLVO theory. The flocculation sediment particle spacing calculation method comprises the following specific steps that firstly, the particle size of single-particle sediment is determined; 2, determining energy conduction between two sediment particles; step 3, determining repulsion energy between two sediment particles; 4, determining the comprehensive action energy between the two particles; 5, calculating the distance between the two sediment particles under the low electrolyte concentration; and 6, calculating the distance between two sediment particles under the condition of medium electrolyte concentration. Aiming at two spherical fine-particle sediments with approximately same particle sizes, the invention provides a method for calculating the flocculation interval of the two spherical fine-particle sediments with the same particle size from the level of a colloid stability theory (DLVO theory), and a better support effect is provided for further knowing the flocculation process, the sedimentation characteristic and the transportation process of the viscous fine-particle sediments.

Description

Technical Field

[0001] The present application relates to the field of fine particle sediment movement calculation, and to a method for calculating the distance between flocculated sediment particles based on the colloidal DLVO theory. Background Art

[0002] In water bodies containing electrolytes, fine sediment particles will adsorb cations to form a double layer, and are affected by van der Waals attraction and double layer repulsion. Van der Waals attraction is independent of the surface charge density between particles, but double layer repulsion depends on the composition and concentration of the electrolyte in the suspension and is closely related to the surface charge density of the particles. When the van der Waals attraction is greater than the double layer repulsion, the sediment particles will flocculate; otherwise, they will disperse. Viscous fine sediment is a mixture of clay, sediment, organic matter and water, and is widely found in rivers, reservoirs, estuaries and coastal waters. Because the viscous fine sediment particles are relatively fine and have significant electrochemical properties, they will collide and bond under certain conditions to form sediment flocs. For areas with weak water flow conditions such as reservoirs, the formation of sediment flocs changes the sedimentation properties of sediment particles, thereby affecting the siltation and service life of sediment in the reservoir area and reducing the flood control and flood storage capacity of the reservoir.

[0003] In order to further understand the flocculation development process and mechanism of viscous fine-grained sediment movement, it is necessary to calculate the distance change process of viscous fine-grained sediment movement and identify the differences in the calculation methods of fine-grained sediment spacing in water bodies with different electrolyte concentrations. This will help improve the understanding of the transport and sedimentation of fine-grained sediment movement, and at the same time provide important theoretical support for analyzing the turbulence and mixing of sand-laden water flow and the surface characteristics of fine-grained sediment. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a method for calculating the distance between flocculated sediment particles based on the colloidal DLVO theory, so as to provide a theoretical basis and technical support for further understanding the floc development, transport and sedimentation processes during the movement of viscous fine-grained sediment.

[0005] To achieve the above objectives, this application provides the following technical solutions:

[0006] The present application embodiment provides a method for calculating the distance between flocculated sediment particles based on the colloidal DLVO theory, including the following specific steps:

[0007] Step 1: Determine the particle size of a single sediment particle;

[0008] Step 2: Determine the attractive energy between two sediment particles;

[0009] Step 3: Determine the repulsive energy between two sediment particles;

[0010] Step 4: Determine the comprehensive interaction energy between the two particles;

[0011] Step 5: Calculate the distance between two sediment particles at low electrolyte concentration;

[0012] Step 6: Calculate the distance between two sediment particles under medium electrolyte concentration.

[0013] The implementation method of step 1 is to use an indoor sediment particle analysis instrument to measure the particle size d of a single sediment particle.

[0014] The implementation of step 2 is as follows:

[0015] Step 31. Compare and screen the single-particle sediment particle size d obtained in step 1 with the critical particle size of fine-particle sediment when flocculation occurs, and determine the actual particle size d′ that can satisfy flocculation;

[0016] Step 32. Based on the colloidal DLVO theory, for two spherical sediment particles with the same particle size, the induction energy is Where H is the Hamker constant, which is a characteristic constant of matter and is related to the properties of the matter. Its order of magnitude is 10-20 joules; r m is the distance between the particle surfaces, in m; d′ is the particle size of a single sediment particle, in m.

[0017] The implementation of step three is as follows:

[0018] According to the double-layer model theory, when particles are close to each other, the double layers on the particle surface will overlap due to the van der Waals force, thereby changing the surface charge distribution and generating repulsion between particles. For spherical particles, the repulsive energy between particles is in, κ -1 is the thickness of the double layer; K is the Boltz constant; n0 is the ion concentration, expressed as the number of ions per cubic centimeter; z is the ion valence on the ion surface; T is the absolute temperature; ε is the dielectric constant of the medium; ε0 is the vacuum dielectric constant; is the particle surface potential.

[0019] The implementation method of step 4 is to add the attraction energy of the two spherical sediment particles with equal particle sizes obtained in step 2 and the repulsion energy of the two spherical sediment particles with equal particle sizes obtained in step 3 to obtain the comprehensive energy, which is specifically: Among them, V represents the comprehensive energy between two spherical sediment particles of equal size.

[0020] The step five is specifically as follows:

[0021] For sandy water with low electrolyte concentration, After sorting, we get make is a constant, then

[0022] The step six is ​​specifically as follows:

[0023] For sandy water with medium electrolyte concentration, Right now make is a constant, then

[0024] Compared with the prior art, the beneficial effect of the present invention is that the distance between two spherical sediment particles of equal particle size can be quickly calculated by simply obtaining the particle size of a single sediment particle, which can provide a reliable reference value for the calculation of floc diameter in sand-containing water bodies. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 It is a schematic diagram of a method flow of an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0028] The terms "comprises," "comprising," or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0029] like Figure 1As shown, the present invention provides a method for calculating the distance between flocculation sediment particles based on the colloidal DLVO theory, which specifically includes the steps of determining the particle size of a single sediment particle, determining the attraction energy between two sediment particles, determining the repulsion energy between two sediment particles, determining the comprehensive interaction energy between the two particles, calculating the distance between two sediment particles under low electrolyte concentration, and calculating the distance between two sediment particles under medium electrolyte concentration.

[0030] Step 1: Use an indoor sediment particle analyzer to measure the particle size d of a single sediment particle;

[0031] Step 2: Determine the attractive energy between two sediment particles;

[0032] For two spherical particles of the same size, the gravitational energy V A for:

[0033]

[0034] In the formula, H is the Hamker constant, which is a characteristic constant of matter and is related to the properties of the matter. Its order of magnitude is 10-20 joules; r m is the distance between particle surfaces, in m; d is the particle size of a single sediment particle, in m.

[0035] Step 3: Determine the repulsive energy between two sediment particles;

[0036] According to the double-layer model theory, when particles are close to each other, the double layers on the particle surface will overlap due to the van der Waals force, thereby changing the surface charge distribution and generating repulsion between particles. For spherical particles, the repulsion between particles V R Expressed as

[0037]

[0038] in, κ -1 It is generally believed that the thickness of the double layer is in meters; K is the Boltz constant 1.3806505×10-23J / K; n0 is the ion concentration, expressed as the number of ions per cubic centimeter; z is the ion valence on the surface of the ion; T is the absolute temperature, equal to +273 degrees Celsius; ε is the dielectric constant of the medium, the dielectric constant of water is 78.5ε0; ε0 is the dielectric constant of vacuum, about 8.8541878×10-12F / m; is the particle surface potential, in volts.

[0039] Step 4: Determine the comprehensive interaction energy between the two particles;

[0040] Combining equation (1) and equation (2), the comprehensive action energy V can be expressed as follows:

[0041]

[0042] In the formula, the symbols have the same meaning as before.

[0043] Step 5: Calculate the distance between two sediment particles at low electrolyte concentration;

[0044] For low electrolyte concentrations, since the potential barrier is a maximum, we have:

[0045]

[0046] It is known that the potential barrier V = 0, that is, V R =-V A , substituting it into formula (4), we can get:

[0047] κr m =1(5)

[0048] Among them, if the electrolyte is a single symmetrical electrolyte, there are:

[0049]

[0050] Substituting equation (5) and equation (6) into equation (3), we can obtain:

[0051]

[0052] Among them,

[0053]

[0054] is a constant, then:

[0055]

[0056] Step 6: Calculate the distance between two sediment particles under medium electrolyte concentration.

[0057] For medium electrolyte concentration, when the potential energy curve has two minimum points, when V = 0, it means that the particles are neither attracted nor repelled, and are in a relatively stable state. That is:

[0058]

[0059] Due to κ -1 It is generally believed that the thickness of the double layer is m ≈κ -1 When r m κ≈1, indicating that when the distance between the two particle surfaces is very close to the thickness of the double electrical layer, then:

[0060]

[0061] make:

[0062]

[0063] It can be seen that is a constant, then:

[0064]

[0065] The above description is only an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for calculating the distance between flocculated sediment particles based on colloidal DLVO theory, characterized in that: The specific steps include: Step 1: Determine the particle size of a single sediment particle; Step 2: Determine the attractive energy between two sediment particles; Step 3: Determine the repulsive energy between two sediment particles; Step 4: Determine the comprehensive interaction energy between the two particles; Step 5: Calculate the distance between two sediment particles at low electrolyte concentration; Step 6: Calculate the distance between two sediment particles under medium electrolyte concentration.

2. The method for calculating the distance between flocculated sediment particles based on colloidal DLVO theory according to claim 1 is characterized in that: The implementation method of step 1 is to use an indoor sediment particle analysis instrument to measure the particle size d of a single sediment particle.

3. The method for calculating the distance between flocculated sediment particles based on colloidal DLVO theory according to claim 2 is characterized in that: The implementation of step 2 is as follows: Step 31. Compare and screen the single-particle sediment particle size d obtained in step 1 with the critical particle size of fine-particle sediment when flocculation occurs, and determine the actual particle size d′ that can satisfy flocculation; Step 32. Based on the colloidal DLVO theory, for two spherical sediment particles with the same particle size, the induction energy is Where H is the Hamker constant, which is a characteristic constant of matter and is related to the properties of the matter. Its order of magnitude is 10-20 joules; r m is the distance between the particle surfaces, in m; d′ is the particle size of a single sediment particle, in m.

4. The method for calculating the distance between flocculated sediment particles based on colloidal DLVO theory according to claim 3 is characterized by: The implementation of step three is as follows: According to the double-layer model theory, when particles are close to each other, the double layers on the particle surface will overlap due to the van der Waals force, thereby changing the surface charge distribution and generating repulsion between particles. For spherical particles, the repulsive energy between particles is in, κ -1 is the thickness of the double layer; K is the Boltz constant; n0 is the ion concentration, expressed as the number of ions per cubic centimeter; z is the ion valence on the ion surface; T is the absolute temperature; ε is the dielectric constant of the medium; ε0 is the vacuum dielectric constant; is the particle surface potential.

5. The method for calculating the distance between flocculated sediment particles based on colloidal DLVO theory according to claim 4 is characterized in that: The implementation method of step 4 is to add the attraction energy of the two spherical sediment particles with equal particle sizes obtained in step 2 and the repulsion energy of the two spherical sediment particles with equal particle sizes obtained in step 3 to obtain the comprehensive energy, which is specifically: Among them, V represents the comprehensive energy between two spherical sediment particles of equal size.

6. The method for calculating the distance between flocculated sediment particles based on colloidal DLVO theory according to claim 5, characterized in that: The step five is specifically as follows: For sandy water with low electrolyte concentration, After sorting, we get make is a constant, then 7. The method for calculating the distance between flocculated sediment particles based on colloidal DLVO theory according to claim 5, characterized in that: The step six is ​​specifically as follows: For sandy water with medium electrolyte concentration, Right now make is a constant, then

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