Degradation of Metal-Organic Framework Materials as Controlled-Release Fertilizers in Crop Fields

Abstract

The behavior of a metal-organic framework (MOF) compound synthesized in hydrothermal reaction conditions and rich in N, P, and Fe nutrients was explored in the field. The attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and laser induced breakdown spectroscopy (LIBS) characterization results showed that the chemical structures changed during the degradation process in crop field soil. The scanning electron microscope images showed that the micro-rod of the MOF peeled off and degraded in layers. During the growth period of wheat, the MOF degraded by 50.9%, with the degradation rate being closely related to soil temperature. It was also found that the degradation rate increased with soil temperature. Moreover, the nutrient concentration of the soil indicated that the MOF had stable nutrients release efficiencies and could provide a continuous supply of nutrients throughout the wheat growth period, which showed a great alternative for MOF as a fertilizer both benefiting agricultural production and environmental protection.

Optimization of metal–organic (citric acid) frameworks for controlled release of nutrients

“…6C). Compared to previously reported nutrient release rates (in compounds using oxalic acid as ligands), 32 the compounds reported here showed higher nutrient release rates. This result is likely due to the difference between ligands.…”

“…The results revealed that the MOF material degraded by 50.9% throughout a wheat season, and exhibited a slow nutrient release rate. 32 Although these materials show potential as controlled-release fertilizers, they are low in N content, which is likely to limit their application in agriculture. Therefore, in this work, we chose an eco-friendly organic ligand and developed two novel MOFs with relatively high nutrient contents.…”

Solvent-Free Synthesis of Iron-Based Metal-Organic Frameworks (MOFs) as Slow-Release Fertilizers

“…The X-ray powder diffraction spectra of compounds I, II, and III were compared with reference OPA-MOF [ 10 ] ( Figure 1 ) and the data of the international diffraction data center. It is found that the three compounds were new phases with crystallinity of 92.28%, 96.72%, and 93.97%, respectively.…”

“… X-ray powder diffraction spectra of MOFs (compounds I, II, and III) and reference oxalate phosphate amine metal organic framework (OPA-MOF) [ 10 ]. …”

“…The highest nitrogen content of the MOF product was 8.2% [ 8 ]. In 2019, Wu et al synthesized OPA-MOF with a similar method [ 9 ], and the nutrient release performance and degradation process were further explored in a rice field, which showed that the collapse of the OPA-MOF structure controlled the slow release of NH 4 + and improved the agronomic traits, rice yield, nitrogen-use efficiency, and nitrogen content in soil [ 10 ]. These studies preliminarily confirmed the potential application of OPA-MOF as a slow-release fertilizer; however, the hydrothermal method with urea as structure-directing agent (SDA) was conventionally used, which caused urea decomposition, required high temperature, generated huge autogenous pressure, and took a long time in the synthesis and drying process.…”