1、Size and shape of soil humic acids estimated by

Ultrafiltration fractions of three soil humic acids were characterized by viscometry and high performance size-exclusion chromatography (HPSEC) in order to estimate shapes and hydrodynamic sizes.

2、Size and Charge Evaluation of Standard Humic and Fulvic Acids as

In this work, the size and charge of humic and fulvic standards purchased from the International Humic Substances Society are presented and discussed.

3、Particle Size of Humic Acid

Using small-angle neutron scattering, we have started a general program intended to analyze the size and shape of humic acids under various environmental conditions.

4、Composition, particle size, charge, and colloidal stability of pH

The purpose of this study was to divide humic acids into several fractions by means of their dissolving in buffers with different pH values and to characterize obtained humic fractions with respect to their composition, structure, particle size, and charge.

Preparation of humic acid fractions with a definite range of particle

Humic acid (HA) are too polydispersed to obtain information bout their particle weight, size and shape. Itis, therefore, desirable about determination of physicochemical parameters of HA toreduce the HA polydispersion by using fractionation techniques.

Adsorption

A new adsorption-based approach for initial estimation of the molecular mass and size of humic acid molecules is proposed, which can be used instead of any specific sophisticated equipment.

Size and shape of soil humic acids estimated by viscosity and

Ultrafiltration fractions of three soil humic acids were characterized by viscometry and high performance size-exclusion chromatography (HPSEC) in order to estimate shapes and hydrodynamic sizes.

Particle size, charge and colloidal stability of humic acids

Humic acids (HA) have a colloidal character whose size and negative charge are strictly dependent on surface functional groups. They are able to complex large amount of poorly ordered iron (hydr)oxides in soil as a function of pH and other environmental conditions.

SKD30019091309290

Using small-angle neutron scattering, we have started a general program intended to analyze the size and shape of humic acids under various environmental conditions.

Particle Size of Humic Acid

The largest humic acid particles that can exist in solutions of the same acidity as most Scandinavian soil and water systems (but at a higher concentration, 1–4 mg/mL) are ≈ 110 nm in their largest dimension; these particles, thus, are of about the same magnitude as large viruses.

Humic acid, a natural organic matter primarily derived from plant residues, animal manure, and microorganisms, plays a crucial role in soil, such as improving soil structure, enhancing fertility, and promoting plant growth. The particle size of humic acid refers to the dimensions of its particles, typically measured in micrometers (μm) or nanometers (nm). The main methods for calculating humic acid particle size are as follows:

1. Microscope Method: This approach involves observing the shape and size of humic acid particles under a microscope. Steps include:

   • Placing the humic acid sample on a glass slide with a drop of distilled water or saline solution.
   • Using low magnification to locate regions with distinct particles.
   • Switching to high magnification to record particle sizes and quantities.
   • Calculating the average particle size based on the distribution of particle counts and sizes.

2. Sedimentation Velocity Method: This method determines particle size by measuring sedimentation rates in a liquid. Steps include:

   • Mixing the humic acid sample with a dye solution to create a uniform suspension.
   • Layering the suspension over a dye solution in a centrifuge tube.
   • Centrifuging for a set time and observing particle settlement.
   • Deriving the average particle size from sedimentation velocity data.

3. Light Scattering Method: This technique uses light scattering properties to determine particle size. Steps include:

   • Preparing a uniform suspension of humic acid and dye solution.
   • Measuring light scattering intensity with a laser scattering instrument.
   • Calculating the average particle size based on scattering intensity variations.

4. Electrophoresis Method: This method measures particle size via migration speed in an electric field. Steps include:

   • Mixing the humic acid sample with a dye solution to form a suspension.
   • Applying an electric field in an electrophoresis apparatus and observing particle movement.
   • Deriving the average particle size from migration velocity data.

5. Granulometry Analyzer: A common instrument for precise particle size measurement. Steps include:

   • Loading the humic acid sample into the analyzer’s sample chamber.
   • Adjusting parameters to match the particle size range.
   • Testing to obtain a particle size distribution curve.
   • Calculating the average particle size from the curve.

various methods exist for determining humic acid particle size, and the choice depends on experimental conditions and requirements. Practical applications require selecting the most suitable method while ensuring accuracy and repeatability in operations.