Sol–gel synthesis of calcium hydroxyapatite thin films …
Comparison of Hydrothermal and Sol-Gel Synthesis of …
The current interest of our research group is largely focused on the development and understanding of precipitated crystalline organometallic compounds. We are placing a strong emphasis in the study of the synthetic procedures, the morphology, and on the structural determination of such compounds. Special importance is engaged in the preparation coordination polymers crystallized from solutions of supercritical CO2, (scCO2), where the use of a co-solvent is occasionally employed depending on reagents solubility [1-3]. The correct selection of experimental conditions in the scCO2 reactive crystallization technique, allows a precipitation known from other methodologies, as well as new crystalline phases. This procedure leads to the crystallization of stable hierarchical nanoestructures involving micro and mesoporosity. As the preparation of the crystalline materials is carried out in scCO2, these obtained with microporous structures were recovered activated, i.e., with open volume, since the removal of any guest molecules from the framework is carried out by simple depressurization. This method is expected to have many potential applications in the development of green crystallization techniques for coordination polymers synthesis.
Experimental Procedure Sol–Gel Synthesis The composites of ..
Inorganic fertilizers along with high yielding varieties have contributed immensely for success of green revolution. Increasing pressure towards food production globally demands unconscientious fertilizer usage in future as well. Nitrogenous fertilizers are the extensively used fertilizers but also suffer huge losses from agriculture ecosystem due to faster rate of release which is not synchronized with crop demand. Thus resulting in low nitrogen use efficiency. In order to have a sustained release of nitrogen from fertilizer, nanoparticle coated with urea is an effective option. We report urea coated hydroxyapatite based nanofertilizer and its performance on aerobic paddy. In this study hydroxyapatite (HA) nanoparticles were synthesized by adding orthophosphoric acid to calcium hydroxide solution under constant vigorous stirring. Saturated urea solution was added to the HA particle suspension and was stirred continuously for 12 hours for surface modification. The urea modified HA particles were washed and dried at 65ºC. Hydroxyapatite nanoparticles (HA) and urea coated hydroxyapatite nanoparticles (UHA) were characterized using Dynamic Light Scattering (DLS), Scanning Electron Microscope (SEM), Powder X-ray Diffraction (PXRD) and Fourier Transform Infrared (FTIR) Spectroscopy. Nitrogen content of UHA was analyzed using Kjeldahl method. Nitrogen content of UHA particles was found to be 36% and Zeta potential was 165.0 mV indicating stable nanodispersion. PXRD pattern of UHA particles indicated the presence of peaks due to hydroxyapatite and urea. SEM images of UHA particles exhibited oblong structures resembling rice grains with diameter less than 90 nm. FTIR spectroscopy showed prominent peaks around γmax/cm–1 1041 indicating phosphate group in hydroxyapatite and γmax/cm–1 3336 and 3432 indicating presence of urea. Synthesized nanofertilizer was evaluated on aerobic paddy under completely randomized design and was compared with recommended dose of conventional urea (100kgN/ha) in aerobic paddy. Nanofertilizer at 25% of recommended dose recorded highest grain yield. Nanofertilizer@ 50% dose showed similar performace to 100% dose of conventional urea. The results indicate amount of fertilizer application into soil can be reduced than regular dosage with nanofertilizer without affecting the yield. This will reduce environmental pollution of water and soil without compromising agricultural production.