Potential Sustainable Slow-Release Fertilizers Obtained by Mechanochemical Activation of MgAl and MgFe Layered Double Hydroxides and K2HPO4

Abstract

This study describes the behavior of potential slow-release fertilizers (SRF), prepared by the mechanochemical activation of calcined Mg2Al-CO3 or Mg2Fe-CO3 layered double hydroxides (LDH) mixed with dipotassium hydrogen phosphate (K2HPO4). 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/K2HPO4 (9 h milling, 2:1 molar ratio, MR). Compared to readily used K2HPO4, milling orthophosphate into LDH matrices decreases its solubility and slows down its release, with 60% and 5.4% release after 168 h for MgAl/K2HPO4 and MgFe/K2HPO4 composites, respectively. Mechanochemical addition of carboxymethylcellulose to the LDH/K2HPO4 composites leads to a noticeable improvement of P release properties.

Nanofertilizers: A Cutting-Edge Approach to Increase Nitrogen Use Efficiency in Grasslands

“…The ionic nature of the clays as well as their ability to host a wide range of organic and inorganic ions in combination with an elevated ion exchange capacity, may render them suitable for controlled or slow nutrients release and thus increasing NUE (Table 1). For example, Layered Double Hydroxide (LDH) (Ureña-Amate et al, 2011;Berber et al, 2013;Koilraj et al, 2013;Borges et al, 2019;Jiang et al, 2019), montmorillonite (MMT) (Golbashy et al, 2016), andZeolite ((Manjaiah et al, 2019) are good examples of a 2D nanostructure clay with promising opportunities as nanofertilizers for grasslands. Another suitable nanomaterial, due to its intrinsic nutrient capacity is the Hydroxyapatite (HT), a nanoparticle that can supply P in a faster and more prolonged manner (biphasic pattern) (Montalvo et al, 2015;Kottegoda et al, 2017).…”

“…According to the type of formulation, nanofertilizers are classified into three categories: 1) nanoscale fertilizer, which corresponds to the conventional fertilizer reduced in size typically in the form of nanoparticles; 2) nanoscale additive fertilizer, is a traditional fertilizer containing a supplement nanomaterial; and 3) nanoscale coating fertilizer, refers to nutrients encapsulated by nanofilms or intercalated into nanoscale pores of a host material (Mastronardi et al, 2015). Encapsulated nutrients by films or held in nanopores within a carrier material such as clays have been used to form nanocomposite structures for controlling the nutrient release (Golbashy et al, 2016;Kottegoda et al, 2017;Borges et al, 2019;Tarafder et al, 2020).…”

Atomic Level Understanding of Orthophosphate Adsorption by Magnesium Aluminum-Layered Double Hydroxides—A Multitechnique Study

“…33,35 Such AOH has clearly been identified by 27 Al SSNMR for MgAl-and ZnAl-LDH phases used for phosphate adsorption. 28,[36][37][38] Moreover, the presence of amorphous aluminum hydroxides is critical as these have a high affinity for phosphate [39][40][41] and will lower the actual Al content in the LDH, 33,[35][36]42 i.e., result in a lower TAC. Thus, experimental techniques with atomic level resolution, which do not require long-range order such as solid-state NMR spectroscopy (SSNMR), X-ray extended absorption spectroscopy (EXAFS), vibrational spectroscopy (FT-IR and Raman) is needed to probe surface complexation and amorphous phases.…”

Layered Double Hydroxide-Based Nanomaterials-From Fundamentals to Applications

“…Such an increased research activity led to progressively growing number of publications in the recent past, seven of which appear in this Special Issue. They include five original research papers [9,10,11,12,13] and two review articles [14,15] from world-class research groups. The topics of these papers are in line with the original goal of the Special Issue, as they range from the synthesis of novel LDHs and LDH-based composites, through their physico-chemical characterization, to applications as fertilizers, drug delivery vehicles, and catalysts.…”

“…The last paper included in this Special issue, submitted by Borges et al [10], is concerned with a different, but also biorelevant topic, namely, the synthesis and characterization of sustainable fertilizers based on Mg/Al- and Mg/Fe-LDH materials. The importance of this topic comes from the fact that new products or methods should be developed to improve nutrient management, which becomes especially important for environmental resilience.…”