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The effect of hydrotalcite, analogues and biological materials on soil water repellency and remediation

Horoch, Owen (2020) The effect of hydrotalcite, analogues and biological materials on soil water repellency and remediation. Honours thesis, Murdoch University.

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Abstract

Soil water repellency (SWR) is a global issue affecting sandy agricultural and native soils on six of the seven continents. These non-wetting soils hinder moisture from entering the soil, inhibiting germination and potentially inducing runoff of agrichemicals when rain does occur. This is especially an issue in the farming sector as it causes reduced crop yields at great expense.

This study aims to test a series of products to determine their viability for being deployed onto hydrophobic soils to amend water repellency. Commercial hydrotalcite was found to contain a hydrophobic coating. It was therefore calcined (300, 400 and 500°C) to remove the coating before being tested as a soil amendment. Two analogues of hydrotalcite (MgFe LDH and CaAl LDH) were also synthesized and characterised for investigation as soil amendments.

Multiple different substances including; MgAl LDH (hydrotalcite), bentonite, compost, algae and biochar were tested on how well they reduced SWR in artificially hydrophobic sand and naturally hydrophobic soil, at loadings between 1 and 5%. Water repellency was measured using the Molarity of ethanol (MED) test. Of all tested substances, calcined hydrotalcite was able to best reduce or completely remove the water repellency, with increasing effectiveness as calcining temperature was increased (300 – 500 °C).

These results lead to the conclusion that the product best suited to ameliorating SWR is 500°C calcined hydrotalcite (MgAl LDH) applied at a loading of 1%.

Item Type: Thesis (Honours)
Murdoch Affiliation(s): Chemistry and Physics
Supervisor(s): Henry, David
URI: http://researchrepository.murdoch.edu.au/id/eprint/58918
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