Research And Development Of Ecotype Water Soluble Compound Fertilizer

Fertigation is a new technology combining fertilization with morden irrigation systemlly. Neutrient and water can be supplied to plant effectively by integrating them organically in irrigation system. It can not only improve the water use efficiency, but also enhance the neutrient utilization, relieve the environmental pollution by fertilizer. Restricted by system property, the fertilizer used in fertigation must be liquid fertilizer or super water soluble solid fertilizer. In view of the current situation that water soluble fertilize used in China are mainly from abroad due to the relative research is just at the beginning stage, the ecotype water soluble compound fertilizer is developed, based on phosphoric acid, urea and potassium chloride as raw materials. The process was studied, and the fundamental physicochemical date was determined systematically. The principal results are as follow:(1) Effects of phosphoric acid concentration, reaction time and crystallization time on urea phosphate (UP) synthesis were studied. The technical parameters are recommended for phosphoric acid concentration of 65%⁷5%, reaction temperature of 70-80 °C , crystallization time of 20²5h in UP synthesis by thermal-process phosphoric acid and urea.(2)The melting point and specific heat of UP were determined by DSC method, the values of which are 117.5°C, and 3.4819J·g^-1-K^-1, respectively.(3) The pH value of UP solution at different concentration were determined by PHS-2C numerable acidimeter. The result shows that pH values varied negative-exponentially with the concentration of solution, which may be a valuable reference for reasonable control in production and application.(4) Solubility of UP in water + phosphoric acid system were measured systematically by synthetic method. Based on knowledge of chemical thermodynamics and related literature, a mathematical model of solubility was induced as follow: lnx = A + B/T + C*lnT , and the solubility data determined were correlated by the equation. The average relative deviation (ARD) between 141 experimental data and calculated data was only 1.61%, the result shows that the data fits the curve very well. The dissolution heat of UP in different solvent (w(H₃PO₄)=0, 0.04390, 0.1091, 0.2160) were predicted by mathematical method as -20.54 kJ·mol^-1, -27.50 kJ·mol^-1, -35.31 kJ·mol^-1 and -32.54 kJ·mol^-1, respectively.(5) The phase equilibrium data of UP-KC1-H₂O ternary system at 20°C, 40°C and 60°C were determined by means of moist solid with radial X diffraction and the corresponding equilibrium diagrams were plotted, and the phase equilibrium data of salt-water system were...