Potential Sustainable Slow-Release Fertilizers Obtained by Mechanochemical Activation of MgAl and MgFe Layered Double Hydroxides and K?HPO?.

ABSTRACT: This study describes the behavior of potential slow-release fertilizers (SRF), prepared by the mechanochemical activation of calcined Mg?Al-CO? or Mg?Fe-CO? layered double hydroxides (LDH) mixed with dipotassium hydrogen phosphate (K?HPO?). The effects of LDH thermal treatment on P/K release behavior were investigated. Characterizations of the inorganic composites before and after release experiments combined X-Ray diffraction (XRD), Fourier-transform infra-red spectroscopy (FTIR), solid-state nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The best release profile (<75% in 28 days and at least 75% release) was obtained for MgAl/K?HPO? (9 h milling, 2:1 molar ratio, MR). Compared to readily used K?HPO?, milling orthophosphate into LDH matrices decreases its solubility and slows down its release, with 60% and 5.4% release after 168 h for MgAl/K?HPO? and MgFe/K?HPO? composites, respectively. Mechanochemical addition of carboxymethylcellulose to the LDH/K?HPO? composites leads to a noticeable improvement of P release properties.

SUBMITTER: Borges R 

PROVIDER: S-EPMC6410234 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature