CONTROLLED RELEASE OF UREA USING MESOPOROUS SILICA

Mesoporous silica has many applications due to its porous and morphological characteristics. This study used mesoporous silica as a carrier of fertilizer for controlled release. Mesoporous silica was synthesized by using cetyltrimethylammonium bromide (CTAB) as a template. Urea was taken as a model fertilizer to study the control release behaviour of mesoporous silica. For loading of urea on silica simple immersion technique was used. The high concentration of urea was taken for loading. In vitro release studies of urea loaded on porous silica in water indicate a fast release of urea within 12 hours, attributed to urea adsorbed on the external surface of porous silica. Then slow and sustained release for the next 4 days, ascribed to urea entrapped in the pores of silica. The release profile of urea loaded in silica synthesized without CTAB was also observed. The release profile of urea loaded on silica gel shows the full urea release within two days. The release profile of Neem-coated urea, commercially used in India as fertilizer, was also studied, in which maximum urea was released within one day. The great potential of developing a fertilizer carrier system based on mesoporous silica was revealed. The nanostructured delivery system for fertilizer could minimize losses of nutrients and consequently reduce the amount applied.