Abstract

Flow Synthesis of Phosphorus Nanocomposites for Controlled Fertilizer Release and Wheat Growth

Volker Hessel, Professor, The University of Adelaide

Flow chemistry has shown distinct advantages in the synthesis of nanomaterials. Here, we investigate flow chemistry for the synthesis of nanofertilizers which has been so far less reported in literature. New generations of P fertilizer have been developed in batch synthesis. In 2020, Hessel et al. proposed a process for leaching phosphorus from mimicked moon crust using a re-entrance flow microfluidic device and using this to fertilize lettuce in “space greenhouses”, and recycling phosphate from lettuce root via burning in a furnace.
 
In this research, a coiled inverted flow system, was used to prepare a slow released P-containing fertilizer and this system also allowed the direct adsorption of low molecular weight organic acid anions (LMWOAs). Citrate ions, as the chosen LMWOAs, were incorporated with the above prepared phosphorus fertiliser to form a compound fertilizer capable of releasing nutrients in a slow manner and reducing the P binding sites in P deficient soil. The nutrient performance was investigated in a model soil mixture. The system allowed the one-stage production of LMWOAs adsorbed apatite with the maximum adsorption capacity of 0.19 gcitrate.gaptite-1 in a continuous manner. The presence of citrate ions in the prepared material increased the P availability in the model soil mixture by 2.6 times compared to commercial apatite. After 14 days of application, about 57% of P in the prepared fertilizer was released into the soil solution.  

We will also report about an extension of the approach here towards nanoencapsulation by chitosan and using more innovative continuous-flow reactor equipment, including the Corning and StoliFlow reactors. We will compare the wheat growth efficiency of the flow-made phosphorus nanofertilizers with plasma-made nitrogen (carbon dot and solution-based) fertilizers, which we also prepare.