Physio-Chemical Preparation of Slow-Release Potassium Fertilizers

Abstract

Background: In this work, one of the novel types of slow-release fertilizers (SRF)
consisting of kaolin as clay material and K2SO4 was synthesized through a
mechanochemical process by grinding in a ball mill planetary model.
Methodology: The test samples of different weight % from 25 to 75 of kaolin contents
were milled for 2 h at fixed milling speeds of about 600 rpm to assess the integration
of K2SO4 and to measure the liberation of K+
and SO4
2-
ions into solution. The
properties of the studied samples were characterized by Fourier transformation infrared
spectrometry (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA),
and ion chromatography (IC). Incorporating K2SO4 into an amorphous kaolin structure
using mechanochemistry is a green chemistry method that has been successfully
applied. K+
content was measured in deionized water solution and the soil column
leaching test was performed to determine the slow-release performance of the material.
Results: The optimum released amount of K+ after 24 h was for (1:1 wt ratio) kaolin -
K2SO4 samples that were 123.9 ppm at milling conditions at 600 rpm milling speed for
2 h.
Conclusion: Indicating th