The Significance of Biot in the Modeling of Nitrogen Release from Urea-Lignin and Improving the Lignin Structure at Nanoscale

Moradi, Samira (2017) The Significance of Biot in the Modeling of Nitrogen Release from Urea-Lignin and Improving the Lignin Structure at Nanoscale. Masters thesis, University of Mohaghegh Ardabili.

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Text (اهمیت بایوت در مدل¬سازي رهش ازت از کود اوره -لیگنین و بهبود ساختار لیگنین در مقیاس نانو) Samira Moradi.pdf Download (1MB) | Preview

Abstract

One of the objective of this thesis is to investigate the effect of hydrodynamic conditions of farmland which happen due to some factors such as wind speed, rainfall and water velocities during irrigation on modeling of pure, matrix and coating urea fertilizers and provide a close to reality model for these systems. Another aim of this study is chemical modification the hydrophilicity of lignin sulfonate nano-particle in order to produce a suitable and hydrophobic coating for controlled release fertilizer. For this purpose, in the modeling section, three close to reality models in finite and infinite volume are presented for pure, coated and matrix urea using the Biot and Sherwood numbers to study hydrodynamic conditions. In pure urea fertilizer, the effect of operating conditions such as speed and temperature in the form of Reynolds and Schmidt numbers in the permissible range that occurs in farmland (600< Re< 3000, 400 <Sc <1500) was evaluated on the number of Sherwood and release rate. The effect of hydrodynamic conditions on release rate in matrix and coating models is also investigated by considering the Biote number. The results showed that with increase Reynolds number due to increased agitator speed, mass transfer coefficient increased, external resistance of mass transfer decreased, Biot number increased and release rate increased, which indicates this parameter and the hydrodynamic condition is effective on the release rate. In the laboratory section, in order to prepare the suitable coating for controlled release fertilizer, lignin sulfonate was extracted using black liquor of wastewater from Mazandaran wood and paper factory. Due to the high solubility of lignin sulphonate in water, the chemical structure should be modified. Due to the difficulty of the lignin sulfonate esterification process, nano particles of lignin sulphonate by sonochemistry was producd in order to facilitate and increase the efficiency of the acetylation process. Extract lignin sulfonate, nanoparticles of lignin sulfonate and their modified state have been identified using FTIR spectra. FE-SEM and DLS analysis also confirm the production of nano particles of lignin sulfonate between 30-50 nm. The production of nano particles of lignin sulfonate reduces time of acetylation from 72 to 24 hours, increases the efficiency from 10 to 50 %, and decreases the acetylation temperature from 80 to 250C than the control sample. The percentage of solubility of modified lignin sulphonate nano-particles in a stirring condition after 48 hours is 50%.; so it is usable as a coating for controlled release of fertilizer.

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