Methenamine-Smectite Clay as Slow Release Fertiliser: Physicochemical and Kinetics Study

Abstract

Slow release fertiliser (SRF) is one of the important materials, which provides benefit to the green chemistry and green chemical engineering in the agricultural applications. Various modifications on porous materials and super-adsorbent based composites have been developed to act as the host for fertilisers including nitrogen- based fertilisers. In this work, a scheme of organic nitrogen compound, methenamine, was used as the SRF compound and in order to increase the effectivity of the releasing nitrogen, immobilisation of the compound in montmorillonite clays has been conducted. Methenamine immobilised montmorillonite at varied methenamine contents (20 mmol/g; 50 mmol/g and 100 mmol/g) was prepared using intercalation process by employing microwave irradiation method. Study on the change of crystallinity and chemical structure of the composite was performed by x-ray diffraction (XRD) analysis, gas sorption analyser, and electronic microscope analysis. The kinetic study of the nitrogen release was conducted by FTIR and HPLC methods. Results showed that physicochemical character of the composite is affected by the methenamine content and the pH of the solution gives influence on the methenamine desorption from the composite.