Fabrication of smart magnetic nanocomposite asymmetric membrane capsules for the controlled release of nitrate

•In this work, a new class of environmentally friendly controlled release fertilizer (CRF) was introduced.•Fe2O3/PES (Polyethersulfone) nanocomposite asymmetric membrane like capsules is designed as new CRF.•The addition of Fe2O3 nanoparticles into the capsules improved their release performance, and provide a chance of magnetic recovering.

Nitrate contamination of water resources due to excessive use of nitrogen-based fertilizers has become a global health issue. In this work, a recyclable and environmentally sensitive magnetic Fe2O3/PES (Polyethersulfone) nanocomposite asymmetric membrane like capsules (NAMCs) were prepared such that release nitrate in a controlled manner. Different characterization techniques such as SEM, EDAX, DSC, and surface energy measurement were used to systematically characterize the NAMCs. It was observed that the incorporation of only 0.5 wt.% Fe2O3 nanoparticles into NAMC provided a slow and steady release rate of nitrate. A further addition of nanoparticles (from 0.5 wt.% to 1.5 wt.%) into the capsules matrix resulted in an increase in the initial-release rate (IRR, from 3.17 to 4.17 μS/cm min) and maximum release level (MRL, from 36 to 52 μS/cm). The designed capsules also showed recyclability and the ability to respond to the environmental conditions. For instance, IRR increased from 3.17 to 5.31 μS/cm min for NAMCs when temperature increased only by 10 °C. These findings could be considered as a new and green approach to prevent nitrate contamination of water resources in the first place without exacerbating energy issues. Although this work is based on the controlled release of nitrate as the water resources contaminant, the NAMCs can also be used for other nutrients and fertilizers.

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