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Colloidal interactions of micro-sized biochar and a kaolinitic soil clay
Nga T Mai1, Anh M Nguyen2, Nga T T Pham3
1Faculty of Environmental Sciences, University of Science, Vietnam National University, Hanoi (VNU), 334 Nguyen Trai, Thanh Xuan, Hanoi, Viet Nam.; Faculty of Environment and Natural Resources, Ha Tay Community College, Thuy Xuan Tien, Chuong My, Hanoi, Viet Nam.
The Science of the Total Environment
|June 12, 2020
Summary
Engineered biochars alter clay mineral dispersion. Pyrolysis conditions and soluble salt content determine if biochar aggregates or disperses clay, impacting soil erosion risks.
Area of Science:
- Soil Science
- Colloid Chemistry
- Environmental Science
Background:
- Biochar and clay minerals are common in soils and aquatic systems.
- Both materials interact with nutrients and contaminants, influencing their transport.
- Understanding their colloidal interactions is crucial for soil and water management.
Purpose of the Study:
- To investigate the effect of engineered micro-sized biochar on the surface charge and colloidal dynamics of kaolinite-rich soil clay.
- To determine how biochar properties, influenced by pyrolysis conditions and solution chemistry, affect clay dispersion.
Main Methods:
- Engineered micro-sized biochars were prepared under different pyrolysis conditions (open heating vs. N2-supported heating).
- Surface charge and colloidal dynamics of kaolinite-rich soil clay were analyzed in the presence of these biochars.
- Solution chemistry (pH, cation type) was varied to assess its influence.
Main Results:
- Biochar properties varied with pyrolysis conditions and solution chemistry.
- Open-heated biochars (O-biochars) with high soluble salts induced clay aggregation by increasing ionic strength and cation bridging.
- N2-supported heated biochars (N2-biochars) low in soluble salts promoted clay dispersion due to negatively charged organic matter.
Conclusions:
- Biochar production methods can be adjusted to control clay dispersion or aggregation.
- O-biochars may reduce short-term clay loss, while N2-biochars favor dispersion.
- Long-term leaching of soluble salts from biochar may increase clay dispersion and erosion risk.
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