Clean and efficient synthesis using mechanochemistry: Preparation of kaolinite–KH2PO4 and kaolinite–(NH4)2HPO4 complexes as slow released fertilizer

Clean and efficient synthesis using mechanochemistry: Preparation of kaolinite–KH2PO4 and kaolinite–(NH4)2HPO4 complexes as slow released fertilizer

This study investigated a mechanochemical process for synthesizing slow-release fertilizers of kaoliniteand KH2PO4/(NH4)2HPO4 in separate systems by milling in a planetary ball mill. Tests with kaolinitecontents ranging from 25 to 75 wt % and mill rotational speeds at 600 rpm for 2 h were performed toevaluate incorporation of KH2PO4 and (NH4)2HPO4 and release of K+, NH4+ and PO43 ions into solution. X-ray diffraction (XRD), Thermal gravimetric analysis (TGA), Fourier transformation infraredspectrometry (FTIR) and ion chromatography (IC) were used to analyze the synthesized samples andindicated that the mechanochemistry (MC) process was successfully applied to incorporate both KH2PO4and (NH4)2HPO4 into the amorphous kaolinite structure. Release of K+ and PO43 ions from the system(kaolinite–KH2PO4) when dispersed in water for 24 h reached up to 15 to 40 ppm respectively. Undersimilar conditions for the system (kaolinite–(NH4)2HPO4), release of NH4+ and PO43 ions reachedbetween 303.2 and 415.1 (ppm) respectively. These results indicated that the MC process could developedto allow amorphous kaolinite to act as a carrier of K+, NH4+ and PO43 nutrients to be released slowly foruse as fertilizer.

This study investigated a mechanochemical process for synthesizing slow-release fertilizers of kaoliniteand KH2PO4/(NH4)2HPO4 in separate systems by milling in a planetary ball mill. Tests with kaolinitecontents ranging from 25 to 75 wt % and mill rotational speeds at 600 rpm for 2 h were performed toevaluate incorporation of KH2PO4 and (NH4)2HPO4 and release of K+, NH4+ and PO43 ions into solution. X-ray diffraction (XRD), Thermal gravimetric analysis (TGA), Fourier transformation infraredspectrometry (FTIR) and ion chromatography (IC) were used to analyze the synthesized samples andindicated that the mechanochemistry (MC) process was successfully applied to incorporate both KH2PO4and (NH4)2HPO4 into the amorphous kaolinite structure. Release of K+ and PO43 ions from the system(kaolinite–KH2PO4) when dispersed in water for 24 h reached up to 15 to 40 ppm respectively. Undersimilar conditions for the system (kaolinite–(NH4)2HPO4), release of NH4+ and PO43 ions reachedbetween 303.2 and 415.1 (ppm) respectively. These results indicated that the MC process could developedto allow amorphous kaolinite to act as a carrier of K+, NH4+ and PO43 nutrients to be released slowly foruse as fertilizer.