Study Of Wastewater Of Pmida And Its Vacuum Evaporation Crystallization Process

PMIDA is the key intermediate in synthesis of Glyphosate in IDA Process. Glyphosate is a broad spectrum herbicide that is effective, harmfulless and nonpersistent, and also has the biggest production and use in the world. During the IDA Process, production of PMIDA discharges waste water which contains aldehyde, phosphorus and salt. Following the increasing needs of Glyphosate market, it becomes more important to study the wastewater treatment of PMIDA. In the paper, we dealwith the wastewater by evaporation crystallization technology, and study systematically both in experiment and theory, including crystallization thermodynamics, crystallization kinetics and crystallization process.Crystallization threomdymics is the key factor in diciding the production yield and the selection of crystallization process. In this thesis, the solubility of PMIDA in different aqueous sodium chloride solutions were measured using a laser technique. The experimental datas were regressed, and got good fitting result. As well, the supersolubility and induction period of PMIDA in water were also determined using the laser technique, and calculated Solid-Liquid interfacial tension. The datas provide the theory basis for the crystallization process and has the instruction significance with operating control and optimization.The nucleation and growth rate in crystallization kinetics have an effect on crystal-size distribution(CSD) and is the basis for understanding of crystallization behavior and crystallizer scale-up design. The kinetics of PMIDA was studied by the moment transformation method. By using the least square method for the multivariate linear regression, the kinetic parameters under the experimental condition were obtained. On the basis of crystallization thermodynamics and crystallization kinetics study, the influence of agitation speed, evaporating temperature on the crystallization process and CSD were studied.Respectively using fractional crystallization, dilution crystallization and evaporation crystallization to treate wastewater, and did experimental research with the three methods. Through process optimization, confirming that the evaporation crystallization-alkaline solution extraction technology could effectively improve mass fraction of PMIDA in the salt, also studied the influence of different concentrations of alkaline solutions, acidification time on the technology.