Abstract

Glasses in the phosphate system acting as slow release fertilizer were synthesized by melt- quenching technique. A new glassmaterial was prepared, which can be used as slowly soluble fertilizer for different type of plants. Glasses were melted at the temperature (800 – 950°C) with a soaking period of 1hr. which was earlier reported to be melted not below 10000c. Leaching study of these glasses with a maximum time period of 300 hrs were conducted under Soxhlet distillation condition with distilled water. A Fourier transform infrared (FTIR) spectrum was recorded in the 400-4000 cm-1 range, revealed optical phonons specification for the phosphate matrix. FTIR studies show absorptions at 760, 879, 920, 1087, 1110, ~ 2193-2870, and ~3440-3500 cm-1. ⁵⁷Fe Mossbauer spectroscopy studies were presented. Mössbauer studies were done in order to analyze their structure. Amorphous nature of glass was confirmed by XRD. The morphology of glass materials was analyzed by Scanning Electron Microscopy. SEM of some selected glasses was presented. X-ray Fluorescence (XRF) technique is used for elemental analysis and chemical analysis. The effect of different modifier ions like Na⁺, Fe³⁺, Mg²⁺, Ca²⁺, and K⁺ in the basic phosphate networks on melting’s and time of melting has been found to be evident. The model structure of glasses has been considered taking the role of some glass formers/ modifiers which ultimately has an effect on the chemical durability of these glasses. For GF (glass fertilizer) minimum solubility was measured for the sample containing Iron Oxide (Fe₂O₃) and maximum solubility for base sample and from GF (glass fertilizer) maximum solubility appeared for the sample with molybdenum oxide. The results of the experiments reported here demonstrate that is possible to adjust the release of phosphate from the fertilizer to phosphate demand of the plant. Weight losses were followed with respect to cumulative time period of leaching. For some glass fertilizer samples, the leach rates as calculated from BET surface area measurements. They were in the range 6.3 x10^–3 to 2.3 x10^-3 g.m^-2.hr^-1 at 90°C. The pH determination ranging from 4.80 up to 7.50 of the leachate solution at ambient temperature under varying time intervals shows interesting and regular variations. The results are in conformity with the change of equilibrium pH under varying leaching time reported by other authors. The leaching study of such glasses under Soxhlet condition shows Ca²⁺, Mg²⁺ and K⁺ to be a candidate as modifier towards leach resistance. The findings have been corroborated in terms of ionic size, ionic radii and hence ionic potential of the modifier ions incorporated into the glass structure. Application of glass fertilizers was done on khariff paddy.