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1. Dispersion/Flocculation is a purely chemical phenomenon, driven by the balance of cations in the soil. Calcium has a very high flocculation power, while sodium and potassium cause dispersion. The general balance between Ca and Mg compared to sodium is what determines flocculation/dispersion.
What causes flocculation in soils?
Soil particles will flocculate if the amount of soluble salts in the soil is increased (increased EC), even if there is a lot of sodium. Soil particles may disperse if the amount of soluble salts in the soil is decreased (i.e. if EC is decreased).
What is soil flocculation?
Definition. Flocculation – process during which particles, for example, of a soil, dispersed in a solution contact and adhere each another, forming clusters, flocks, flakes, or clumps of a larger size. The term originates from the word “floc,” which is the flake of precipitate that comes out of solution.
Which are the flocculation agent in soil?
Sodium silicate is specified as the de- flocculating agent in the present ASTM and AASHO standard methods of mechanical analysis. Sodium pyrophosphate and so- dium metaphosphate have been found ef- fective as deflocculating agents lor many types of soil (1, 5, 6).
What is flocculant structure?
Flocculated structure is present in clay particles which contains larger surface area. When there is net attractive force between the particles, then positive charged particles attracted towards negatively charged faces which results the formation of flocculated structure.
Which ion causes dispersion in soil?
When the ratio of sodium to other ions at these exchange sites is high, clay particles are less tightly bound to each other and the soil aggregates easily disperse when the soil becomes wet.
What is the purpose of the flocculation process?
Flocculation is a process by which a chemical coagulant added to the water acts to facilitate bonding between particles, creating larger aggregates which are easier to separate. The method is widely used in water treatment plants and can also be applied to sample processing for monitoring applications.
What is the importance of soil pH in soil analysis?
A pH of 7 indicates a neutral soil. The pH is important because it influences the availability of essential nutrients. Most horticultural crops will grow satisfactorily in soils having a pH between 6 (slightly acid) and 7.5 (slightly alkaline).
What is red soil made of?
It is formed by the weathering of ancient crystalline and metamorphic rocks, particularly acid granites and gneisses, quartzitic rocks, and felspathic rocks. Chemically, red soil is siliceous and aluminous, with free quartz as sand, but is rich in potassium, ranging from sand to clay with the majority being loamy.
Does lime Flocculate clay soil?
Lime is considered to be a soil conditioner. It can be used to raise the pH of a soil to make it less acidic. It will also flocculate clay particles so they will form crumbs rather than clods.
What is flocculating agent example?
Abstract. Flocculating agents are chemical additives that cause suspended solids to form aggregates called flocs. These agents are used in water treatment, municipal and industrial waste treatment, mineral processing, and papermaking. Flocculating agents are either inorganic salts or water-soluble organic polymers.
What is a Deflocculant agent?
: an agent that causes deflocculation specifically : a chemical (as sodium carbonate) added to a clay slip to minimize settling out.
Why does sodium cause dispersion?
Effects of Sodium and Sodicity on Soil Physical Properties The forces that bind clay particles together are disrupted when too many large sodium ions come between them. When this separation occurs, the clay particles expand, causing swelling and soil dispersion.
What are the 5 basic types of soil structure?
Types. There are five major classes of structure seen in soils: platy, prismatic, columnar, granular, and blocky. There are also structureless conditions. Some soils have simple structure, each unit being an entity without component smaller units.
What is cohesive strength of soil?
Cohesion of soil is an important factor of soil consistency. In soil physics, BA VER (2), for example, defines it as “the cohesive force that takes place between adja- cent particles”. On the other hand, in soil mechanics, cohesion means “the shear strength when the compressive stresses are equal to zero”.
What are the soil properties which are influenced by soil structure?
The mineral components of soil are sand, silt and clay, and their relative proportions determine a soil’s texture. Properties that are influenced by soil texture include porosity, permeability, infiltration, shrink-swell rate, water-holding capacity, and susceptibility to erosion.
Which is the primary source of salt in soil?
The main source of all salts in the soil is the primary minerals in the exposed layer of the earth’s crust. During the process of chemical weathering which involves hydrolysis, hydration, solution, oxidation, carbonation and other processes, the salt constituents are gradually released and made soluble.
In which type of soils dispersed structure is found?
Dispersed Structure: When clay soils are remoulded, their flocculated structure changes and particles change their orientation from edge-to-face orientation to face-to-face orientation. This kind of formed soil structure is called dispersed soil structure.
How do you identify sodic soil?
A sodic soil is defined as a soil with an exchangeable sodium of greater than 6% of the cation exchange capacity. Non-saline sodic soils are usually dispersive in the presence of fresh water. Saline-sodic clays are less dispersive than non-saline-sodic soils and have higher infiltration rates.
How can flocculation be prevented?
When particles of a suspension come close together they can form aggregates called flocculates which will settle more rapidly. To prevent that we often coat the particle with a charged surfactant. The charge (Zeta potential) acts to keep the particles separate and prevent flocculation.
Where is flocculation used?
Flocculation is a water treatment process where solids form larger clusters, or flocs, to be removed from water. This process can happen spontaneously, or with the help of chemical agents. It is a common method of stormwater treatment, wastewater treatment, and in the purification of drinking water.
How is flocculation done?
Surface chemistry In colloid chemistry, flocculation refers to the process by which fine particulates are caused to clump together into a floc. The floc may then float to the top of the liquid (creaming), settle to the bottom of the liquid (sedimentation), or be readily filtered from the liquid.
