The Measurement Of Liquid Diffusion Coefficient Of Phosphate Fertilizer Based On A Liquid-Core Cylindrical Lens

Liquid diffusion coefficient（D）is a fundamental parameter in the study of mass-transfer process,the calculation of mass-transfer rate,the design and development of chemical equipment.In this paper,the D of three phosphate fertilizer aqueous with temperature were measured by using asymmetric liquid-core cylindrical lens（ALCL）as imaging element and diffusion cell.A series of diffusion images at different times were measured and analyzed,the spatial distribution of the refractive index（RI）is obtained.The D is obtained based on experimental datum and Fick’second law.The measurement result is compared with the Taylor dispersion method,which verifies the reliability of the measurement of D of three kinds of phosphate fertilizer aqueous solution has important application value for the establishment and solution of mathematical model of lake water pollution process.Which has important scientific and environmental significance in the prevention and control of lake water pollution.The main research contents and results as following:First of all,the D of diammonium hydrogen phosphate（DAP）,ammonium dihydrogen phosphate（MAP）and phostassium dihydrogen phosphate（KDP）aqueous solutions at room temperature（293.15 K）with infinite dilute were measure by using ALCL as imaging element and diffusion cell.Secondly,the temperature of the diffusion solution was accurately controlled by a semiconductor temperature control device.In the temperature range from 293.15 K to 318.15 K,the D of three kinds of phosphate fertilizer aqueous solutions were measured by “the equivalent RI of thin liquid layer method”.The measurement at different temperatures are in good consistent with the Arrihenius formula.Thirdly,the temperature from 293.15 K to 318.15 K,the D of three phosphate fertilizer aqueous solutions were measured by the high performance liquid chromatography（HPLC）based on the principle of Taylor dispersion method and related calculation equation.It was found that the D are also in good consistent with the Arrhenius formula.Finally,the results of the equivalent RI of thin liquid layer method and Taylor dispersion method are analyzed and compared.It is found that the D measured by the two methods are closely,and both D meet the Arrhenius formula.The measurement show that the D meet the Arrhenius expression of three phosphate fertilizer aqueous solutions obtained by two independent measurement methods are reliable.