Modified Layered Nanohybrid Structures for the Slow Release of Urea

Urea intercalated layered material nanohybrid formulations based on two types of layered clays, layered double hydroxides and montmorillonite were developed for agricultural applications as slow release nitrogen plant nutrient formulations. The resulting nanohybrids were prepared by the intercalation of urea between the nanolayers of clay matrixes. The successful intercalation of the guest urea molecule was confirmed using the number of solid state characterization techniques and the possible structure of urea between the layers was deduced. Urea molecules are expected to be bound through their carbonyl and amine modes to the nanolayers of the clay with several interaction modes of different bond strengths. Thus, electrostatic interactions between urea and the nanoclay layers would reduce the rate of hydrolysis of urea and decomposition into gaseous products. Release behavior of urea of nanohybrids was studied in water and compared with that of pure urea. Both nanohybrid formulations displayed significant degree of slow release behavior.