CONTROLLED RELEASE OF FERTILISER USING MESOPOROUS SILICA NANOPARTICLES

Abstract

Nanostructured delivery systems for fertilizers could minimize leaching and consequently reduce the amountsapplied. In this study, Mesoporous Silica Nanoparticles (MSNs) were explored as controlled release carriers forfertilizers. A series of MSNs with particle sizes, Barrett-Joyner-Halenda (BJH) pore diameters, Brunauer-Emmett-Teller (BET) surface areas and BJH total pore volumes ranging between 50 nm – 900 nm, 2.4 nm - 4.4 nm, 589 m2g-1- 1013 m2g-1 and 0.61 cm3g-1 – 0.81 cm3g-1 respectively were synthesized via Liquid Crystal Templating Mechanism(LCT). Urea was used as a model fertilizer to access the fertilizer loading and controlled release behaviour of MSNs.Loading was achieved by a simple immersion technique using concentrated aqueous urea solution. As much as19.8 % - 78.2 % of the MSNs surface areas and 16.8 % - 99.0 % of the mesopore volumes were loaded with ureamolecules, mainly by physisorption. In vitro release studies of urea-loaded MSNs (UMSNs) in water indicated aburst release (32 % - 91 %) within the 1st day attributed to the urea adsorbed on the external surfaces, followed bya slow and sustained release for up to 6 days when all urea was released (100 %), ascribed to urea moleculesentrapped in the mesopores. The release profiles were found to vary with the physical properties of MSNs. Greatpotential for the development of fertilizer nanocarrier systems based on MSNs was revealed.